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| 1. | Diddigi, Raghuram Bharadwaj; Chandramouli Kamanchi, Shalabh Bhatnagar A Convergent Off-Policy Temporal Difference Algorithm Conference Forthcoming 24th European Conference on Artificial Intelligence – ECAI 2020, Forthcoming. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Raghuram, title = {A Convergent Off-Policy Temporal Difference Algorithm}, author = {Raghuram Bharadwaj Diddigi and Chandramouli Kamanchi, Shalabh Bhatnagar}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/08/A-Convergent-Off-Policy-Temporal-Difference-Algorithm.pdf}, year = {2020}, date = {2020-08-29}, booktitle = {24th European Conference on Artificial Intelligence – ECAI 2020}, abstract = {Learning the value function of a given policy (target policy) from the data samples obtained from a different policy (behavior policy) is an important problem in Reinforcement Learning (RL). This problem is studied under the setting of off-policy prediction. Temporal Difference (TD) learning algorithms are a popular class of algorithms for solving the prediction problem. TD algorithms with linear function approximation are shown to be convergent when the samples are generated from the target policy (known as on-policy prediction). However, it has been well established in the literature that off-policy TD algorithms under linear function approximation diverge. In this work, we propose a convergent on-line off-policy TD algorithm under linear function approximation. The main idea is to penalize the updates of the algorithm in a way as to ensure convergence of the iterates. We provide a convergence analysis of our algorithm. Through numerical evaluations, we further demonstrate the effectiveness of our algorithm.}, keywords = {Electrical Communications Engineering}, pubstate = {forthcoming}, tppubtype = {conference} } Learning the value function of a given policy (target policy) from the data samples obtained from a different policy (behavior policy) is an important problem in Reinforcement Learning (RL). This problem is studied under the setting of off-policy prediction. Temporal Difference (TD) learning algorithms are a popular class of algorithms for solving the prediction problem. TD algorithms with linear function approximation are shown to be convergent when the samples are generated from the target policy (known as on-policy prediction). However, it has been well established in the literature that off-policy TD algorithms under linear function approximation diverge. In this work, we propose a convergent on-line off-policy TD algorithm under linear function approximation. The main idea is to penalize the updates of the algorithm in a way as to ensure convergence of the iterates. We provide a convergence analysis of our algorithm. Through numerical evaluations, we further demonstrate the effectiveness of our algorithm. |
| 2. | Serge Kas Hanna; Rawad Bitar; Parimal Parag; Venkat Dasari, ; Salim El, Rouayheb Adaptive Distributed Stochastic Gradient Descent for Minimizing Delay in the Presence of Stragglers Conference 45th International Conference on Acoustics, Speech, and Signal Processing, Barcelona, May 4-8, 2020, 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Parimal2020, title = {Adaptive Distributed Stochastic Gradient Descent for Minimizing Delay in the Presence of Stragglers}, author = {Serge Kas Hanna; Rawad Bitar; Parimal Parag; Venkat Dasari, and Salim El, Rouayheb}, url = {http://10.0.54.4/wp-content/uploads/2020/02/Adaptive-Distributed-Stochastic-Gradient-Descent-for-Minimizing-delay-in-the-presence-of-Stragglers.pdf}, year = {2020}, date = {2020-05-05}, booktitle = {45th International Conference on Acoustics, Speech, and Signal Processing, Barcelona, May 4-8, 2020}, abstract = {We consider the setting where a master wants to run a distributed stochastic gradient descent (SGD) algorithm on n workers each having a subset of the data. Distributed SGD may suffer from the effect of stragglers, i.e., slow or unresponsive workers who cause delays. One solution studied in the literature is to wait at each iteration for the responses of the fastest k < n workers before updating the model, where k is a fixed parameter. The choice of the value of k presents a trade-off between the runtime (i.e., convergence rate) of SGD and the error of the model. Towards optimizing the error-runtime trade-off, we investigate distributed SGD with adaptive k. We first design an adaptive policy for varying k that optimizes this trade-off based on an upper bound on the error as a function of the wallclock time which we derive. Then, we propose an algorithm for adaptive distributed SGD that is based on a statistical heuristic. We implement our algorithm and provide numerical simulations which confirm our intuition and theoretical analysis}, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {conference} } We consider the setting where a master wants to run a distributed stochastic gradient descent (SGD) algorithm on n workers each having a subset of the data. Distributed SGD may suffer from the effect of stragglers, i.e., slow or unresponsive workers who cause delays. One solution studied in the literature is to wait at each iteration for the responses of the fastest k < n workers before updating the model, where k is a fixed parameter. The choice of the value of k presents a trade-off between the runtime (i.e., convergence rate) of SGD and the error of the model. Towards optimizing the error-runtime trade-off, we investigate distributed SGD with adaptive k. We first design an adaptive policy for varying k that optimizes this trade-off based on an upper bound on the error as a function of the wallclock time which we derive. Then, we propose an algorithm for adaptive distributed SGD that is based on a statistical heuristic. We implement our algorithm and provide numerical simulations which confirm our intuition and theoretical analysis |
| 3. | Gaurav Bhandari; Prakash Hiremath Ashish, Joglekar Anupama Kulkarni; Devadatta Kulkarni; Mahadeva; Sampad Mohanty; Raghunath; MB Raju; Rajeev Shorey; Rajesh Sundaresan An Implementation of an Industrial Internet ofThings on an SMT Assembly Line Conference COMSNETS 2020, 2020. Abstract | BibTeX | Tags: Industrial Internet of Things | Links: @conference{@Bhandari, title = {An Implementation of an Industrial Internet ofThings on an SMT Assembly Line}, author = {Gaurav Bhandari; Prakash Hiremath, Ashish, Joglekar, Anupama, Kulkarni; Devadatta, Kulkarni; Mahadeva; Sampad, Mohanty; Raghunath; MB,Raju; Rajeev, Shorey; Rajesh, Sundaresan}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/An-Implementation-of-an-Industrial-Internet-ofThings-on-an-SMT-Assembly-Line.pdf}, year = {2020}, date = {2020-01-15}, booktitle = {COMSNETS 2020}, abstract = {Industry 4.0 is the latest trend in the manufacturingsector that focuses on intelligent manufacturing and smart facto-ries. This leads to opportunities in automation, optimization, assetmanagement and predictive maintenance, which helps reducedowntime and increase revenue. In this paper, we propose thesolution that was created for a particular SMT PCB manufactur-ing facility in Mysuru (Vinyas IT), the features it has to offer andthe methodologies that were implemented in order to achieve ourgoals. We will also highlight the important aspects of the solutionthat will be showcased during the demonstration and the impactof our solution.}, keywords = {Industrial Internet of Things}, pubstate = {published}, tppubtype = {conference} } Industry 4.0 is the latest trend in the manufacturingsector that focuses on intelligent manufacturing and smart facto-ries. This leads to opportunities in automation, optimization, assetmanagement and predictive maintenance, which helps reducedowntime and increase revenue. In this paper, we propose thesolution that was created for a particular SMT PCB manufactur-ing facility in Mysuru (Vinyas IT), the features it has to offer andthe methodologies that were implemented in order to achieve ourgoals. We will also highlight the important aspects of the solutionthat will be showcased during the demonstration and the impactof our solution. |
| 4. | Shubhada Agrawal; Siddharth Bhandari; Anirban Bhattacharjee; Anand Deo; Narendra M, Dixit; Prahladh Harsha; Sandeep Juneja; Poonam Kesarwani; Aditya Krishna Swamy; Preetam Patil; Nihesh Rathod; Ramprasad Saptharishi; Sharad Shriram; Piyush Srivastava; Rajesh Sundaresan; Nidhin Koshy Vaidhiyan; Sarath Yasodharan City-Scale Agent-Based Simulators for the Study of Non-Pharmaceutical Interventions in the Context of the COVID-19 Epidemic Technical Report 2020. Abstract | BibTeX | Tags: Centre for Networked Intelligence | Links: @techreport{@Shubhada, title = {City-Scale Agent-Based Simulators for the Study of Non-Pharmaceutical Interventions in the Context of the COVID-19 Epidemic}, author = {Shubhada Agrawal; Siddharth Bhandari; Anirban Bhattacharjee; Anand Deo; Narendra M, Dixit; Prahladh Harsha; Sandeep Juneja; Poonam Kesarwani; Aditya Krishna Swamy; Preetam Patil; Nihesh Rathod; Ramprasad Saptharishi; Sharad Shriram; Piyush Srivastava; Rajesh Sundaresan; Nidhin Koshy Vaidhiyan; Sarath Yasodharan}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/City-Scale-Agent-Based-Simulators-for-the-study-of-Non-Pharmaceutical-Interventions-in-the-Context-of-the-COVID-19-Epidemic.pdf}, year = {2020}, date = {2020-08-11}, abstract = {We highlight the usefulness of city-scale agent-based simulators in studying various nonpharmaceutical interventions to manage an evolving pandemic. We ground our studies in the context of the COVID-19 pandemic and demonstrate the power of the simulator via several exploratory case studies in two metropolises, Bengaluru and Mumbai. Such tools become common-place in any city administration’s tool kit in our march towards digital health.}, keywords = {Centre for Networked Intelligence}, pubstate = {published}, tppubtype = {techreport} } We highlight the usefulness of city-scale agent-based simulators in studying various nonpharmaceutical interventions to manage an evolving pandemic. We ground our studies in the context of the COVID-19 pandemic and demonstrate the power of the simulator via several exploratory case studies in two metropolises, Bengaluru and Mumbai. Such tools become common-place in any city administration’s tool kit in our march towards digital health. |
| 5. | Lima Agnel Tony; Shuvrangshu Jana; Varun V P; Vidyadhara, BV; Mohitvishnu Gaddey; Abhishek Kashyap; Rahul Ravichandran; Debasish Ghose Collaborative Tracking and Capture of Aerial Object using UAVs Conference Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February., 2020. Abstract | BibTeX | Tags: MBZIRC | Links: @conference{@Lima, title = {Collaborative Tracking and Capture of Aerial Object using UAVs }, author = {Lima Agnel Tony; Shuvrangshu Jana; Varun V P; Vidyadhara, BV; Mohitvishnu Gaddey; Abhishek Kashyap; Rahul Ravichandran; Debasish Ghose}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Collaborative-Tracking-and-Capture-of-Aerial-Object-using-UAVs.pdf}, year = {2020}, date = {2020-02-20}, booktitle = {Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February.}, abstract = {This work details the problem of aerial target capture using multiple UAVs. This problem is motivated from the challenge 1 of Mohammed Bin Zayed International Robotic Challenge 2020. The UAVs utilise visual feedback to autonomously detect target, approach it and capture without disturbing the vehicle which carries the target. Multi-UAV collaboration improves the effciency of the system and increases the chance of capturing the ball robustly in short span of time. In this paper, the proposed architecture is validated through simulation in ROS-Gazebo environment and is further implemented on hardware.}, keywords = {MBZIRC}, pubstate = {published}, tppubtype = {conference} } This work details the problem of aerial target capture using multiple UAVs. This problem is motivated from the challenge 1 of Mohammed Bin Zayed International Robotic Challenge 2020. The UAVs utilise visual feedback to autonomously detect target, approach it and capture without disturbing the vehicle which carries the target. Multi-UAV collaboration improves the effciency of the system and increases the chance of capturing the ball robustly in short span of time. In this paper, the proposed architecture is validated through simulation in ROS-Gazebo environment and is further implemented on hardware. |
| 6. | Srikrishna Acharya; Amrutur Bharadwaj; Yogesh Simmhan; Aditya Gopalan; Parimal Parag; Himanshu, Tyagi CORNET: A Co-Simulation Middleware for Robot Networks Conference 12th International Conference on COMmunication Systems & NETworkS, Bengaluru, Jan 7-11, 2019, 2020. Abstract | BibTeX | Tags: Robotics @conference{@Srikrishna20, title = {CORNET: A Co-Simulation Middleware for Robot Networks}, author = {Srikrishna Acharya; Amrutur Bharadwaj; Yogesh Simmhan; Aditya Gopalan; Parimal Parag; Himanshu,Tyagi}, year = {2020}, date = {2020-01-06}, booktitle = {12th International Conference on COMmunication Systems & NETworkS, Bengaluru, Jan 7-11, 2019}, abstract = {This paper describes CORNET, a co-simulation middleware for applications involving multi-robot systems like a network of Unmanned Aerial Vehicle (UAV) systems. Design of such systems requires knowledge of the flight dynamics of UAVs and the communication links connecting UAVs with each other or with the ground control station. Besides, UAV networks are dynamic and distinctive from other ad-hoc networks and require protocols that can adapt to high-mobility, dynamic topology and changing link quality in power constrained resource platforms. Therefore, it is necessary to co-design the UAV path planning algorithms and the communication protocols. The proposed co-simulation framework integrates existing tools to simulate flight dynamics and network related aspects. Gazebo with robot operating system (ROS) is used as a physical system UAV simulator and NS-3 is used as a network simulator, to jointly capture the cyber-physical system (CPS) aspects of the multi- UAV systems. A particular aspect we address is on synchronizing time and position across the two simulation environments, and we provide APIs to allow easy migration of the algorithms to real platforms.}, keywords = {Robotics}, pubstate = {published}, tppubtype = {conference} } This paper describes CORNET, a co-simulation middleware for applications involving multi-robot systems like a network of Unmanned Aerial Vehicle (UAV) systems. Design of such systems requires knowledge of the flight dynamics of UAVs and the communication links connecting UAVs with each other or with the ground control station. Besides, UAV networks are dynamic and distinctive from other ad-hoc networks and require protocols that can adapt to high-mobility, dynamic topology and changing link quality in power constrained resource platforms. Therefore, it is necessary to co-design the UAV path planning algorithms and the communication protocols. The proposed co-simulation framework integrates existing tools to simulate flight dynamics and network related aspects. Gazebo with robot operating system (ROS) is used as a physical system UAV simulator and NS-3 is used as a network simulator, to jointly capture the cyber-physical system (CPS) aspects of the multi- UAV systems. A particular aspect we address is on synchronizing time and position across the two simulation environments, and we provide APIs to allow easy migration of the algorithms to real platforms. |
| 7. | Nihesh Rathod; Renu Subramanian; Rajesh, Sundaresan Coverage Estimation in Outdoor Heterogeneous Propagation Environments Journal Article IEEE Access, 8 , pp. 31660 - 31673, 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @article{@Nihesh2020, title = {Coverage Estimation in Outdoor Heterogeneous Propagation Environments}, author = {Nihesh Rathod; Renu Subramanian; Rajesh,Sundaresan}, url = {http://10.0.54.4/wp-content/uploads/2020/03/Coverage-Estimation-in-Outdoor-Heterogeneous-Propagation-Environments.pdf}, doi = { 10.1109/ACCESS.2020.2972811}, year = {2020}, date = {2020-02-10}, journal = { IEEE Access}, volume = {8}, pages = { 31660 - 31673}, abstract = {This paper is on a coverage estimation procedure for the deployment of outdoor Internet of Things (IoT). In the first part of the paper, a data-driven coverage estimation technique is proposed. The estimation technique combines multiple machine-learning-based regression ideas. The proposed technique achieves two purposes. The first purpose is to reduce the bias in the estimated received signal strength arising from estimations performed only on the successfully received packets. The second purpose is to exploit commonality of physical parameters, e.g. antenna-gain, in measurements that are made across multiple propagation environments. It also provides the correct link function for performing a nonlinear regression in our communication systems context. In the second part of the paper, a method to use readily available geographic information system (GIS) data (for classifying geographic areas into various propagation environments) followed by an algorithm for estimating received signal strength (which is motivated by the first part of the paper) is proposed. Together they enable quick and automated estimation of coverage in outdoor environments. It is anticipated that these will lead to faster and more efficient deployment of outdoor. Internet of Things}, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {article} } This paper is on a coverage estimation procedure for the deployment of outdoor Internet of Things (IoT). In the first part of the paper, a data-driven coverage estimation technique is proposed. The estimation technique combines multiple machine-learning-based regression ideas. The proposed technique achieves two purposes. The first purpose is to reduce the bias in the estimated received signal strength arising from estimations performed only on the successfully received packets. The second purpose is to exploit commonality of physical parameters, e.g. antenna-gain, in measurements that are made across multiple propagation environments. It also provides the correct link function for performing a nonlinear regression in our communication systems context. In the second part of the paper, a method to use readily available geographic information system (GIS) data (for classifying geographic areas into various propagation environments) followed by an algorithm for estimating received signal strength (which is motivated by the first part of the paper) is proposed. Together they enable quick and automated estimation of coverage in outdoor environments. It is anticipated that these will lead to faster and more efficient deployment of outdoor. Internet of Things |
| 8. | Prahladh Harsha; Sandeep Juneja; Preetam Patil; Nihesh Rathod; Ramprasad Saptharishi; AY Sarath; Sharad Sriram; Piyush Srivastava; Rajesh Sundaresan; Nidhin Koshy, Vaidhiyan COVID-19 Epidemic Study II: Phased emergence from the Lockdown in Mumbai Technical Report 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @techreport{@Prahladh, title = {COVID-19 Epidemic Study II: Phased emergence from the Lockdown in Mumbai}, author = {Prahladh Harsha; Sandeep Juneja; Preetam Patil; Nihesh Rathod; Ramprasad Saptharishi; AY Sarath; Sharad Sriram; Piyush Srivastava; Rajesh Sundaresan; Nidhin Koshy,Vaidhiyan}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/08/COVID-19-Epidemic-Study-II-Phased-Emergence-from-the-lockdown-in-Mumbai.pdf}, year = {2020}, date = {2020-06-05}, abstract = {The nation-wide lockdown starting 25 March 2020, aimed at suppressing the spread of the COVID-19 disease, was extended until 31 May 2020 in three subsequent orders by the Government of India. The extended lockdown has had significant social and economic consequences and `lockdown fatigue' has likely set in. Phased reopening began from 01 June 2020 onwards. Mumbai, one of the most crowded cities in the world, has witnessed both the largest number of cases and deaths among all the cities in India (41986 positive cases and 1368 deaths as of 02 June 2020). Many tough decisions are going to be made on re-opening in the next few days. In an earlier IISc-TIFR Report, we presented an agent-based city-scale simulator(ABCS) to model the progression and spread of the infection in large metropolises like Mumbai and Bengaluru. As discussed in IISc-TIFR Report 1, ABCS is a useful tool to model interactions of city residents at an individual level and to capture the impact of non-pharmaceutical interventions on the infection spread. In this report we focus on Mumbai. Using our simulator, we consider some plausible scenarios for phased emergence of Mumbai from the lockdown, 01 June 2020 onwards. These include phased and gradual opening of the industry, partial opening of public transportation (modelling of infection spread in suburban trains), impact of containment zones on controlling infections, and the role of compliance with respect to various intervention measures including use of masks, case isolation, home quarantine, etc. The main takeaway of our simulation results is that a phased opening of workplaces, say at a conservative attendance level of 20 to 33%, is a good way to restart economic activity while ensuring that the city's medical care capacity remains adequate to handle the possible rise in the number of COVID-19 patients in June and July. }, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {techreport} } The nation-wide lockdown starting 25 March 2020, aimed at suppressing the spread of the COVID-19 disease, was extended until 31 May 2020 in three subsequent orders by the Government of India. The extended lockdown has had significant social and economic consequences and `lockdown fatigue' has likely set in. Phased reopening began from 01 June 2020 onwards. Mumbai, one of the most crowded cities in the world, has witnessed both the largest number of cases and deaths among all the cities in India (41986 positive cases and 1368 deaths as of 02 June 2020). Many tough decisions are going to be made on re-opening in the next few days. In an earlier IISc-TIFR Report, we presented an agent-based city-scale simulator(ABCS) to model the progression and spread of the infection in large metropolises like Mumbai and Bengaluru. As discussed in IISc-TIFR Report 1, ABCS is a useful tool to model interactions of city residents at an individual level and to capture the impact of non-pharmaceutical interventions on the infection spread. In this report we focus on Mumbai. Using our simulator, we consider some plausible scenarios for phased emergence of Mumbai from the lockdown, 01 June 2020 onwards. These include phased and gradual opening of the industry, partial opening of public transportation (modelling of infection spread in suburban trains), impact of containment zones on controlling infections, and the role of compliance with respect to various intervention measures including use of masks, case isolation, home quarantine, etc. The main takeaway of our simulation results is that a phased opening of workplaces, say at a conservative attendance level of 20 to 33%, is a good way to restart economic activity while ensuring that the city's medical care capacity remains adequate to handle the possible rise in the number of COVID-19 patients in June and July. |
| 9. | P. N. Karthik, Rajesh Sundaresan Detecting an Odd Restless Markov Arm with a Trembling Hand Conference IEEE International Symposium on Information Theory, 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Karthik, title = {Detecting an Odd Restless Markov Arm with a Trembling Hand}, author = {P. N. Karthik, Rajesh Sundaresan}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Detecting-an-Odd-Restless-Markov-Arm-with-a-Trembling-Hand.pdf}, year = {2020}, date = {2020-07-25}, booktitle = {IEEE International Symposium on Information Theory}, journal = {arXiv:2005.06255}, abstract = {In this paper, we consider a multi-armed bandit in which each arm is a Markov process evolving on a finite state space. The state space is common across the arms, and the arms are independent of each other. The transition probability matrix of one of the arms (the odd arm) is different from the common transition probability matrix of all the other arms. A decision maker, who knows these transition probability matrices, wishes to identify the odd arm as quickly as possible, while keeping the probability of decision error small. To do so, the decision maker collects observations from the arms by pulling the arms in a sequential manner, one at each discrete time instant. However, the decision maker has a trembling hand, and the arm that is actually pulled at any given time differs, with a small probability, from the one he intended to pull. The observation at any given time is the arm that is actually pulled and its current state. The Markov processes of the unobserved arms continue to evolve. This makes the arms restless. For the above setting, we derive the first known asymptotic lower bound on the expected time required to identify the odd arm, where the asymptotics is of vanishing error probability. The continued evolution of each arm adds a new dimension to the problem, leading to a family of Markov decision problems (MDPs) on a countable state space. We then stitch together certain parameterised solutions to these MDPs and obtain a sequence of strategies whose expected times to identify the odd arm come arbitrarily close to the lower bound in the regime of vanishing error probability. Prior works dealt with independent and identically distributed (across time) arms and rested Markov arms, whereas our work deals with restless Markov arms. }, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {conference} } In this paper, we consider a multi-armed bandit in which each arm is a Markov process evolving on a finite state space. The state space is common across the arms, and the arms are independent of each other. The transition probability matrix of one of the arms (the odd arm) is different from the common transition probability matrix of all the other arms. A decision maker, who knows these transition probability matrices, wishes to identify the odd arm as quickly as possible, while keeping the probability of decision error small. To do so, the decision maker collects observations from the arms by pulling the arms in a sequential manner, one at each discrete time instant. However, the decision maker has a trembling hand, and the arm that is actually pulled at any given time differs, with a small probability, from the one he intended to pull. The observation at any given time is the arm that is actually pulled and its current state. The Markov processes of the unobserved arms continue to evolve. This makes the arms restless. For the above setting, we derive the first known asymptotic lower bound on the expected time required to identify the odd arm, where the asymptotics is of vanishing error probability. The continued evolution of each arm adds a new dimension to the problem, leading to a family of Markov decision problems (MDPs) on a countable state space. We then stitch together certain parameterised solutions to these MDPs and obtain a sequence of strategies whose expected times to identify the odd arm come arbitrarily close to the lower bound in the regime of vanishing error probability. Prior works dealt with independent and identically distributed (across time) arms and rested Markov arms, whereas our work deals with restless Markov arms. |
| 10. | Nirabhra Mandal; Pavankumar, Tallapragada Evolution of a Population of Selfish Agents on a Network Conference IFAC World Congress 2020, 2020. Abstract | BibTeX | Tags: Control and Optimisation | Links: @conference{@Nirabhra, title = {Evolution of a Population of Selfish Agents on a Network}, author = {Nirabhra Mandal; Pavankumar, Tallapragada}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Evolution-of-a-Population-of-Selfish-Agents-on-a-Network.pdf}, year = {2020}, date = {2020-07-17}, booktitle = {IFAC World Congress 2020}, abstract = {In this work, we consider a population composed of a continuum of agents that seek to selfishly minimize a cost function by moving on a network. The nodes in the network may represent physical locations or abstract choices. Taking inspiration from how water distributes itself in a system of connected tanks of varying heights, we formulate a best response dynamics for the population. In this dynamics, the population in each node simultaneously seeks to redistribute itself according to the `best response' to the state of the population in the node's neighborhood. We provide an algorithm to determine the best response as a function of the state of the population. We then show that given the state of the population, the best response is unique. For the continuous time version of the best response dynamics, we show asymptotic convergence to an equilibrium point for an arbitrary initial condition. We then explore a second dynamics, in which the population evolves according to centralized gradient descent of the social cost. Again, we show asymptotic convergence for an arbitrary initial condition. We illustrate our results through simulations.}, keywords = {Control and Optimisation}, pubstate = {published}, tppubtype = {conference} } In this work, we consider a population composed of a continuum of agents that seek to selfishly minimize a cost function by moving on a network. The nodes in the network may represent physical locations or abstract choices. Taking inspiration from how water distributes itself in a system of connected tanks of varying heights, we formulate a best response dynamics for the population. In this dynamics, the population in each node simultaneously seeks to redistribute itself according to the `best response' to the state of the population in the node's neighborhood. We provide an algorithm to determine the best response as a function of the state of the population. We then show that given the state of the population, the best response is unique. For the continuous time version of the best response dynamics, we show asymptotic convergence to an equilibrium point for an arbitrary initial condition. We then explore a second dynamics, in which the population evolves according to centralized gradient descent of the social cost. Again, we show asymptotic convergence for an arbitrary initial condition. We illustrate our results through simulations. |
| 11. | CG Jansson; R, Thottappillil; Hillman; Möller; KVS Hari; Sundaresan R Experiments in creating online course content for signal processing education Conference ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Jansson, title = {Experiments in creating online course content for signal processing education}, author = {CG, Jansson; R, Thottappillil; Hillman; Möller; KVS,Hari; R, Sundaresan }, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Experiments-in-Creating-Online-Course-Content-for-Signal-Processing-Education.pdf}, doi = {10.1109/ICASSP40776.2020.9054289}, year = {2020}, date = {2020-05-14}, booktitle = { ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)}, abstract = {The creation of the NPTEL platform in India has led to a vast population of engineering students getting access to quality online content for Signal Processing. These courses are globally accessible, free of cost, and also provide a means of obtaining certificates of proficiency by taking a proctored examination. Recently, a European Union funded project, MIELES, has supported the activity of creating online courses in the fields related to Signal Processing. This paper presents the details and experiences of creating course content and presents guidelines for prospective content creators.}, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {conference} } The creation of the NPTEL platform in India has led to a vast population of engineering students getting access to quality online content for Signal Processing. These courses are globally accessible, free of cost, and also provide a means of obtaining certificates of proficiency by taking a proctored examination. Recently, a European Union funded project, MIELES, has supported the activity of creating online courses in the fields related to Signal Processing. This paper presents the details and experiences of creating course content and presents guidelines for prospective content creators. |
| 12. | Sagar Gubbi; Shishir Kolathaya; Bharadwaj, Amrutur Imitation Learning for High Precision Peg-in-Hole Tasks Conference 6th International Conference on Control, Automation and Robotics (ICCAR), 2020. Abstract | BibTeX | Tags: Robotics | Links: @conference{@Sagar, title = {Imitation Learning for High Precision Peg-in-Hole Tasks}, author = { Sagar Gubbi; Shishir Kolathaya; Bharadwaj, Amrutur }, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Imitation-Learning-for-High-Precision-Peg-in-Hole-Tasks.pdf}, doi = {10.1109/ICCAR49639.2020.9108072}, year = {2020}, date = {2020-06-04}, booktitle = {6th International Conference on Control, Automation and Robotics (ICCAR)}, pages = {2251-2446 }, abstract = {Industrial robot manipulators are not able to match the precision and speed with which humans are able to execute contact rich tasks even to this day. Therefore, as a means to overcome this gap, we demonstrate generative methods for imitating a peg-in-hole insertion task in a 6-DOF robot manipulator. In particular, generative adversarial imitation learning (GAIL) is used to successfully achieve this task with a 6 μm peg-hole clearance on the Yaskawa GP8 industrial robot. Experimental results show that the policy successfully learns within 20 episodes from a handful of human expert demonstrations on the robot (i.e., <; 10 tele-operated robot demonstrations). The insertion time improves from > 20 seconds (which also includes failed insertions) to <; 15 seconds, thereby validating the effectiveness of this approach.}, keywords = {Robotics}, pubstate = {published}, tppubtype = {conference} } Industrial robot manipulators are not able to match the precision and speed with which humans are able to execute contact rich tasks even to this day. Therefore, as a means to overcome this gap, we demonstrate generative methods for imitating a peg-in-hole insertion task in a 6-DOF robot manipulator. In particular, generative adversarial imitation learning (GAIL) is used to successfully achieve this task with a 6 μm peg-hole clearance on the Yaskawa GP8 industrial robot. Experimental results show that the policy successfully learns within 20 episodes from a handful of human expert demonstrations on the robot (i.e., <; 10 tele-operated robot demonstrations). The insertion time improves from > 20 seconds (which also includes failed insertions) to <; 15 seconds, thereby validating the effectiveness of this approach. |
| 13. | Laishram, Rokesh Lateral Compression of Tubes - Numerical Predictions: Reid and Reddy Revisited Journal Article XXV ICTAM, 23-28 August 2020, Milano, Italy, 2020. Abstract | BibTeX | Tags: Autonomous Systems @article{@Rokeshb, title = {Lateral Compression of Tubes - Numerical Predictions: Reid and Reddy Revisited}, author = {Rokesh Laishram}, year = {2020}, date = {2020-08-23}, journal = {XXV ICTAM, 23-28 August 2020, Milano, Italy}, abstract = {Numerical validation is carried out to ensure the agreement between the predicted results and the actual observations in the experiment. This paper predicts some of the observations of T.Y. Reddy [1] on the experiments conducted on lateral compression of circular single tubes and crossed layers of tubes crushed between flat parallel platens. Quasi-static experimental results are predicted using the finite element LS_DYNA simulation software package. Other prediction includes the deformed shape of single tube and single crossed layer tubes. The predictions are carried out for aluminium specimens. The predicted load-displacement data matches well with the experimental results. It also captures small details like the change in load-deflection curve when the bottom tube touches the top platen and top plate touching the bottom rigid plate in cross tube in experiment.}, keywords = {Autonomous Systems}, pubstate = {published}, tppubtype = {article} } Numerical validation is carried out to ensure the agreement between the predicted results and the actual observations in the experiment. This paper predicts some of the observations of T.Y. Reddy [1] on the experiments conducted on lateral compression of circular single tubes and crossed layers of tubes crushed between flat parallel platens. Quasi-static experimental results are predicted using the finite element LS_DYNA simulation software package. Other prediction includes the deformed shape of single tube and single crossed layer tubes. The predictions are carried out for aluminium specimens. The predicted load-displacement data matches well with the experimental results. It also captures small details like the change in load-deflection curve when the bottom tube touches the top platen and top plate touching the bottom rigid plate in cross tube in experiment. |
| 14. | SK Kadambari, Sundeep Prabhakar Chepuri Learning Product Graphs from Multidomain Signals Conference ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP), 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Kadambari20, title = {Learning Product Graphs from Multidomain Signals}, author = {SK Kadambari, Sundeep Prabhakar Chepuri}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/11/LEARNING-PRODUCT-GRAPHS-FROM-MULTIDOMAIN-SIGNALS.pdf}, doi = { 10.1109/ICASSP40776.2020.9054679}, year = {2020}, date = {2020-05-14}, booktitle = {ICASSP 2020 - 2020 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP)}, abstract = {In this paper, we focus on learning the underlying product graph structure from multidomain training data. We assume that the product graph is formed from a Cartesian graph product of two smaller factor graphs. We then pose the product graph learning problem as the factor graph Laplacian matrix estimation problem. To estimate the factor graph Laplacian matrices, we assume that the data is smooth with respect to the underlying product graph. When the training data is noise free or complete, learning factor graphs can be formulated as a convex optimization problem, which has an explicit solution based on the water-filling algorithm. The developed framework is illustrated using numerical experiments on synthetic data as well as real data related to air quality monitoring in India.}, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {conference} } In this paper, we focus on learning the underlying product graph structure from multidomain training data. We assume that the product graph is formed from a Cartesian graph product of two smaller factor graphs. We then pose the product graph learning problem as the factor graph Laplacian matrix estimation problem. To estimate the factor graph Laplacian matrices, we assume that the data is smooth with respect to the underlying product graph. When the training data is noise free or complete, learning factor graphs can be formulated as a convex optimization problem, which has an explicit solution based on the water-filling algorithm. The developed framework is illustrated using numerical experiments on synthetic data as well as real data related to air quality monitoring in India. |
| 15. | Sashank Tirumala; Sagar Gubbi; Kartik Paigwar; Aditya Sagi; Ashish Joglekar; Shalabh Bhatnagar; Ashitava Ghosal; Bharadwaj Amrutur; Shishir, Kolathaya Learning Stable Manoeuvres for Quadruped Robots from Expert Demonstrations Conference 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN), 2020. Abstract | BibTeX | Tags: Walking Robot | Links: @conference{@Shashank, title = {Learning Stable Manoeuvres for Quadruped Robots from Expert Demonstrations}, author = {Sashank Tirumala; Sagar Gubbi; Kartik Paigwar; Aditya Sagi; Ashish Joglekar; Shalabh Bhatnagar; Ashitava Ghosal; Bharadwaj Amrutur; Shishir, Kolathaya}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Learning-Stable-Manoeuvres-in-Quadruped-Robots-from-Expert-Demonstrations.pdf}, year = {2020}, date = {2020-07-28}, booktitle = {29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)}, abstract = {With the research into development of quadruped robots picking up pace, learning based techniques are being explored for developing locomotion controllers for such robots. A key problem is to generate leg trajectories for continuously varying target linear and angular velocities, in a stable manner. In this paper, we propose a two pronged approach to address this problem. First, multiple simpler policies are trained to generate trajectories for a discrete set of target velocities and turning radius. These policies are then augmented using a higher level neural network for handling the transition between the learned trajectories. Specifically, we develop a neural network-based filter that takes in target velocity, radius and transforms them into new commands that enable smooth transitions to the new trajectory. This transformation is achieved by learning from expert demonstrations. An application of this is the transformation of a novice user's input into an expert user's input, thereby ensuring stable manoeuvres regardless of the user's experience. Training our proposed architecture requires much less expert demonstrations compared to standard neural network architectures. Finally, we demonstrate experimentally these results in the in-house quadruped Stoch 2. }, keywords = {Walking Robot}, pubstate = {published}, tppubtype = {conference} } With the research into development of quadruped robots picking up pace, learning based techniques are being explored for developing locomotion controllers for such robots. A key problem is to generate leg trajectories for continuously varying target linear and angular velocities, in a stable manner. In this paper, we propose a two pronged approach to address this problem. First, multiple simpler policies are trained to generate trajectories for a discrete set of target velocities and turning radius. These policies are then augmented using a higher level neural network for handling the transition between the learned trajectories. Specifically, we develop a neural network-based filter that takes in target velocity, radius and transforms them into new commands that enable smooth transitions to the new trajectory. This transformation is achieved by learning from expert demonstrations. An application of this is the transformation of a novice user's input into an expert user's input, thereby ensuring stable manoeuvres regardless of the user's experience. Training our proposed architecture requires much less expert demonstrations compared to standard neural network architectures. Finally, we demonstrate experimentally these results in the in-house quadruped Stoch 2. |
| 16. | P N, Karthik; Rajesh Sundaresan Learning to Detect an Odd Markov Arm Journal Article IEEE Transactions on Information Theory, 66 (7), pp. 4324-4348, 2020. Abstract | BibTeX | Tags: Information Theory | Links: @article{Karthik2020, title = {Learning to Detect an Odd Markov Arm}, author = {P N, Karthik; Rajesh Sundaresan}, url = {http://10.0.54.4/wp-content/uploads/2019/09/Learning-to-detect-an-odd-markov-arm.pdf}, year = {2020}, date = {2020-07-01}, journal = {IEEE Transactions on Information Theory}, volume = {66}, number = {7}, pages = {4324-4348}, abstract = {A multi-armed bandit with finitely many arms is studied when each arm is a homogeneous Markov process on an underlying finite state space. The transition law of one of the arms, referred to as the odd arm, is different from the common transition law of all other arms. A learner, who has no knowledge of the above transition laws, has to devise a sequential test to identify the index of the odd arm as quickly as possible, subject to an upper bound on the probability of error. For this problem, we derive an asymptotic lower bound on the expected stopping time of any sequential test of the learner, where the asymptotics is as the probability of error vanishes. Furthermore, we propose a sequential test, and show that the asymptotic behaviour of its expected stopping time comes arbitrarily close to that of the lower bound. Prior works deal with iid arms, whereas our work deals with Markov arms. Our analysis of the rested Markov setting is a key first step in understanding the difficult case of restless Markov setting, which is still open.}, keywords = {Information Theory}, pubstate = {published}, tppubtype = {article} } A multi-armed bandit with finitely many arms is studied when each arm is a homogeneous Markov process on an underlying finite state space. The transition law of one of the arms, referred to as the odd arm, is different from the common transition law of all other arms. A learner, who has no knowledge of the above transition laws, has to devise a sequential test to identify the index of the odd arm as quickly as possible, subject to an upper bound on the probability of error. For this problem, we derive an asymptotic lower bound on the expected stopping time of any sequential test of the learner, where the asymptotics is as the probability of error vanishes. Furthermore, we propose a sequential test, and show that the asymptotic behaviour of its expected stopping time comes arbitrarily close to that of the lower bound. Prior works deal with iid arms, whereas our work deals with Markov arms. Our analysis of the rested Markov setting is a key first step in understanding the difficult case of restless Markov setting, which is still open. |
| 17. | Kolathaya, Shishir Local stability of PD controlled bipedal walking robots Journal Article Automatica, 114 (108841), 2020. Abstract | BibTeX | Tags: Robotics | Links: @article{@Shishir2020, title = {Local stability of PD controlled bipedal walking robots}, author = {Shishir Kolathaya}, url = {http://10.0.54.4/wp-content/uploads/2019/12/PD-based-Robust-Quadratic-Programs-for-Robotic-Systems.pdf}, doi = {https://doi.org/10.1016/j.automatica.2020.108841}, year = {2020}, date = {2020-04-01}, journal = {Automatica}, volume = {114}, number = {108841}, abstract = {We establish stability results for PD tracking control laws in bipedal walking robots. Stability of PD control laws for continuous robotic systems is an established result, and we extend this for hybrid robotic systems, an alternating sequence of continuous and discrete events. Bipedal robots have the leg-swing as the continuous event, and the foot-strike as the discrete event. In addition, bipeds largely have underactuations due to the interactions between feet and ground. For each continuous event, we establish that the convergence rate of the tracking error can be regulated via appropriate tuning of the PD gains; and for each discrete event, we establish that this convergence rate sufficiently overcomes the nonlinear impacts by assumptions on the hybrid zero dynamics. The main contributions are (1) Extension of the stability results of PD control laws for underactuated robotic systems, and (2) Exponential ultimate boundedness of hybrid periodic orbits under the assumption of exponential stability of their projections to the hybrid zero dynamics. Towards the end, we will validate these results in a 2-link bipedal walker in simulation.}, keywords = {Robotics}, pubstate = {published}, tppubtype = {article} } We establish stability results for PD tracking control laws in bipedal walking robots. Stability of PD control laws for continuous robotic systems is an established result, and we extend this for hybrid robotic systems, an alternating sequence of continuous and discrete events. Bipedal robots have the leg-swing as the continuous event, and the foot-strike as the discrete event. In addition, bipeds largely have underactuations due to the interactions between feet and ground. For each continuous event, we establish that the convergence rate of the tracking error can be regulated via appropriate tuning of the PD gains; and for each discrete event, we establish that this convergence rate sufficiently overcomes the nonlinear impacts by assumptions on the hybrid zero dynamics. The main contributions are (1) Extension of the stability results of PD control laws for underactuated robotic systems, and (2) Exponential ultimate boundedness of hybrid periodic orbits under the assumption of exponential stability of their projections to the hybrid zero dynamics. Towards the end, we will validate these results in a 2-link bipedal walker in simulation. |
| 18. | Rakshit Ramesh; Mukunth Arunachalam; Hari Krishna Atluri; Chetan Kumar; SVR Anand; Paventhan Arumugam; Bharadwaj, Amrutur LoRaWAN for smart cities: experimental study in a campus deployment, Book Chapter in for IoT, Book Chapter LPWAN Technologies; Applications, M2M (Ed.): pp. 327-345, Academic Press, 2020. Abstract | BibTeX | Tags: Smart City | Links: @inbook{@Rakshit, title = {LoRaWAN for smart cities: experimental study in a campus deployment,}, author = {Rakshit Ramesh; Mukunth Arunachalam; Hari Krishna Atluri; Chetan Kumar; SVR Anand; Paventhan Arumugam; Bharadwaj, Amrutur}, editor = {Book Chapter in LPWAN Technologies for IoT and M2M Applications}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/LoRaWAN-for-Smart-Cities-Experimental-Study-in-a-Campus-Deployment.pdf}, doi = {10.1016/B978-0-12-818880-4.00016-8}, year = {2020}, date = {2020-08-01}, pages = {327-345}, publisher = {Academic Press}, abstract = {The advent of cheap low-powered long-range radio technologies such as LoRa that operate on an unlicensed band resulted in many real-world deployments of smart city applications. Unlike a rural and semiurban areas where we can expect long radio-frequency (RF) propagation due to strong line-of-sight component, a city that typically comprises diverse terrain environments comprising a mix of buildings, dense wooded areas, parks, and gated communities limits the radio coverage and range. This necessitates the need for proper RF network planning to ensure optimal coverage of the network in such areas with the ability to remotely manage the infrastructure equipment to make deployment and network management hassle-free. On a city scale, there is a need for an interoperable middleware that provides a single point of contact for a developer to operate devices on various network protocols such as LoRa and Zigbee. In this chapter, we describe our experiences in deploying such an interoperable long-range wide-area network and management aspects of it in a campus environment with dense foliage interspersed with buildings and shed light on some deployment insights we have obtained in order to make an optimal network deployment.}, keywords = {Smart City}, pubstate = {published}, tppubtype = {inbook} } The advent of cheap low-powered long-range radio technologies such as LoRa that operate on an unlicensed band resulted in many real-world deployments of smart city applications. Unlike a rural and semiurban areas where we can expect long radio-frequency (RF) propagation due to strong line-of-sight component, a city that typically comprises diverse terrain environments comprising a mix of buildings, dense wooded areas, parks, and gated communities limits the radio coverage and range. This necessitates the need for proper RF network planning to ensure optimal coverage of the network in such areas with the ability to remotely manage the infrastructure equipment to make deployment and network management hassle-free. On a city scale, there is a need for an interoperable middleware that provides a single point of contact for a developer to operate devices on various network protocols such as LoRa and Zigbee. In this chapter, we describe our experiences in deploying such an interoperable long-range wide-area network and management aspects of it in a campus environment with dense foliage interspersed with buildings and shed light on some deployment insights we have obtained in order to make an optimal network deployment. |
| 19. | Rawad Bitar; Parimal Parag, Salim El Rouayheb Minimizing Latency for Secure Coded Computing Using Secret Sharing via Staircase Codes Journal Article Forthcoming https://arxiv.org/abs/1802.02640, Forthcoming. Abstract | BibTeX | Tags: Electrical Communications Engineering @article{@Rawad2020, title = {Minimizing Latency for Secure Coded Computing Using Secret Sharing via Staircase Codes}, author = {Rawad Bitar; Parimal Parag, Salim El Rouayheb}, year = {2020}, date = {2020-08-01}, journal = { https://arxiv.org/abs/1802.02640}, abstract = {We consider the setting of a Master server, M, who possesses confidential data (e.g., personal, genomic or medical data) and wants to run intensive computations on it, as part of a machine learning algorithm for example. The Master wants to distribute these computations to untrusted workers who have volunteered or are incentivized to help with this task. However, the data must be kept private and not revealed to the individual workers. Some of the workers may be stragglers, e.g., slow or busy, and will take a random time to finish the task assigned to them. We are interested in reducing the delays experienced by the Master. We focus on linear computations as an essential operation in many iterative algorithms such as principal component analysis, support vector machines and other gradient-descent based algorithms. A classical solution is to use a linear secret sharing scheme, such as Shamir's scheme, to divide the data into secret shares on which the workers can perform linear computations. However, classical codes can provide straggler mitigation assuming a worst-case scenario of a fixed number of stragglers. We propose a solution based on new secure codes, called Staircase codes, introduced previously by two of the authors. Staircase codes allow flexibility in the number of stragglers up to a given maximum, and universally achieve the information theoretic limit on the download cost by the Master, leading to latency reduction. Under the shifted exponential model, we find upper and lower bounds on the Master's mean waiting time. We derive the distribution of the Master's waiting time, and its mean, for systems with up to two stragglers. For systems with any number of stragglers, we derive an expression that can give the exact distribution, and the mean, of the waiting time of the Master. We show that Staircase codes always outperform classical secret sharing codes.}, keywords = {Electrical Communications Engineering}, pubstate = {forthcoming}, tppubtype = {article} } We consider the setting of a Master server, M, who possesses confidential data (e.g., personal, genomic or medical data) and wants to run intensive computations on it, as part of a machine learning algorithm for example. The Master wants to distribute these computations to untrusted workers who have volunteered or are incentivized to help with this task. However, the data must be kept private and not revealed to the individual workers. Some of the workers may be stragglers, e.g., slow or busy, and will take a random time to finish the task assigned to them. We are interested in reducing the delays experienced by the Master. We focus on linear computations as an essential operation in many iterative algorithms such as principal component analysis, support vector machines and other gradient-descent based algorithms. A classical solution is to use a linear secret sharing scheme, such as Shamir's scheme, to divide the data into secret shares on which the workers can perform linear computations. However, classical codes can provide straggler mitigation assuming a worst-case scenario of a fixed number of stragglers. We propose a solution based on new secure codes, called Staircase codes, introduced previously by two of the authors. Staircase codes allow flexibility in the number of stragglers up to a given maximum, and universally achieve the information theoretic limit on the download cost by the Master, leading to latency reduction. Under the shifted exponential model, we find upper and lower bounds on the Master's mean waiting time. We derive the distribution of the Master's waiting time, and its mean, for systems with up to two stragglers. For systems with any number of stragglers, we derive an expression that can give the exact distribution, and the mean, of the waiting time of the Master. We show that Staircase codes always outperform classical secret sharing codes. |
| 20. | Kumar Ankit; Lima Agnel Tony; Shuvrangshu Jana; Debasish, Ghose Multi Agent Collaboration for Building Construction Conference Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February, 2020., 2020. Abstract | BibTeX | Tags: MBZIRC | Links: @conference{@Kumar, title = {Multi Agent Collaboration for Building Construction}, author = {Kumar Ankit; Lima Agnel Tony; Shuvrangshu Jana; Debasish, Ghose}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Multi-Agent-Collaboration-for-Building-Construction.pdf}, year = {2020}, date = {2020-09-08}, booktitle = {Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February, 2020.}, abstract = {This paper details the algorithms involved and task planner for vehicle collaboration in building a structure. This is the problem defined in the challenge 2 of Mohammed Bin Zayed International Robotic Challenge 2020 (MBZIRC). The work addresses various aspects of the challenge for Unmanned Aerial Vehicles (UAVs) and Unmanned Ground Vehicle (UGV). Challenge involves repeated pick and place operations using UAVs and UGV to build two structures of different shape and sizes. The algorithms are implemented using Robot Operating System (ROS) frame work and visualised in Gazebo. The whole developed architecture could readily be implemented in suitable hardware}, keywords = {MBZIRC}, pubstate = {published}, tppubtype = {conference} } This paper details the algorithms involved and task planner for vehicle collaboration in building a structure. This is the problem defined in the challenge 2 of Mohammed Bin Zayed International Robotic Challenge 2020 (MBZIRC). The work addresses various aspects of the challenge for Unmanned Aerial Vehicles (UAVs) and Unmanned Ground Vehicle (UGV). Challenge involves repeated pick and place operations using UAVs and UGV to build two structures of different shape and sizes. The algorithms are implemented using Robot Operating System (ROS) frame work and visualised in Gazebo. The whole developed architecture could readily be implemented in suitable hardware |
| 21. | Sagar Gubbi Venkatesh; Raviteja Upadrashta; Shishir Kolathaya; Bharadwaj, Amrutur Multi-Instance Aware Localization for End to End Imitation Learning Conference Forthcoming IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), Forthcoming. Abstract | BibTeX | Tags: Robotics | Links: @conference{@Sagarb, title = {Multi-Instance Aware Localization for End to End Imitation Learning}, author = {Sagar Gubbi Venkatesh; Raviteja Upadrashta; Shishir Kolathaya; Bharadwaj, Amrutur}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Multi-Instance-Aware-Localization-for-End-to-End-Imitation-Learning.pdf}, year = {2020}, date = {2020-10-30}, booktitle = { IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)}, abstract = {Existing architectures for imitation learning using image-to-action policy networks perform poorly when presented with an input image containing multiple instances of the object of interest, especially when the number of expert demonstrations available for training are limited. We show that endto-end policy networks can be trained in a sample efficient manner by (a) appending the feature map output of the vision layers with an embedding that can indicate instance preference or take advantage of an implicit preference present in the expert demonstrations, and (b) employing an autoregressive action generator network for the control layers. The proposed architecture for localization has improved accuracy and sample efficiency and can generalize to the presence of more instances of objects than seen during training. When used for end-to-end imitation learning to perform reach, push, and pick-and-place tasks on a real robot, training is achieved with as few as 15 expert demonstrations.}, keywords = {Robotics}, pubstate = {forthcoming}, tppubtype = {conference} } Existing architectures for imitation learning using image-to-action policy networks perform poorly when presented with an input image containing multiple instances of the object of interest, especially when the number of expert demonstrations available for training are limited. We show that endto-end policy networks can be trained in a sample efficient manner by (a) appending the feature map output of the vision layers with an embedding that can indicate instance preference or take advantage of an implicit preference present in the expert demonstrations, and (b) employing an autoregressive action generator network for the control layers. The proposed architecture for localization has improved accuracy and sample efficiency and can generalize to the presence of more instances of objects than seen during training. When used for end-to-end imitation learning to perform reach, push, and pick-and-place tasks on a real robot, training is achieved with as few as 15 expert demonstrations. |
| 22. | Vipul Kumar Sharma; Pavankumar, Tallapragada Observability of Discrete-Time LTI Systems under Unknown Piece-wise Constant Inputs Journal Article 2020. Abstract | BibTeX | Tags: Control and Optimisation | Links: @article{@Vipul, title = {Observability of Discrete-Time LTI Systems under Unknown Piece-wise Constant Inputs}, author = {Vipul Kumar Sharma; Pavankumar, Tallapragada}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Observability-of-Discrete-Time-LTI-Systems-under-Unknown-Piece-wise-Constant-Inputs.pdf}, year = {2020}, date = {2020-12-31}, abstract = {This paper is on observability of discrete-time LTI systems under unknown piece-wise constant inputs with sufficiently slow, but arbitrary update times. Assuming knowledge of the update times, we characterize the unobservable subspace and show that with sufficiently many measurements in each inter-update interval of the input, the unobservable subspace remains fixed. We explore the implications of the result for privacy in event-triggered control through an illustrative example.}, keywords = {Control and Optimisation}, pubstate = {published}, tppubtype = {article} } This paper is on observability of discrete-time LTI systems under unknown piece-wise constant inputs with sufficiently slow, but arbitrary update times. Assuming knowledge of the update times, we characterize the unobservable subspace and show that with sufficiently many measurements in each inter-update interval of the input, the unobservable subspace remains fixed. We explore the implications of the result for privacy in event-triggered control through an illustrative example. |
| 23. | Pratik Sharma; Devam Awasare; Bishal Jaiswal; Srivats Mohan; Abinaya N; Ishan Darwhekar; Anand SVR; Bharadwaj Amrutur; Aditya Gopalan; Parimal Parag; Himanshu, Tyagi On the Latency in Vehicular Control using Video Streaming over Wi-Fi Conference Forthcoming 26th National Conference on Communications, IIT Kharagpur, 21-23 February 2020, Forthcoming. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @conference{@Pratik2020, title = {On the Latency in Vehicular Control using Video Streaming over Wi-Fi}, author = {Pratik Sharma; Devam Awasare; Bishal Jaiswal; Srivats Mohan; Abinaya,N; Ishan Darwhekar; Anand SVR; Bharadwaj Amrutur; Aditya Gopalan; Parimal Parag; Himanshu,Tyagi}, url = {http://10.0.54.4/wp-content/uploads/2020/02/On-the-Latency-in-Vehicular-Control-using-Video-Streaming-over-Wi-Fi.pdf}, year = {2020}, date = {2020-02-23}, booktitle = {26th National Conference on Communications, IIT Kharagpur, 21-23 February 2020}, abstract = {We consider the use of Wi-Fi (IEEE 802.11n/r) network for remote control of a vehicle using video transmission on the uplink and control signals for the actuator on the downlink. We have setup a network with multiple access points (AP) providing indoor and outdoor coverage, which connects an unmanned ground vehicle (UGV) to a remote command center. Additionally, our setup includes a redundant IEEE 802.11p link for sending control messages over downlink with high reliability and low latency. We study the end-to-end communication delay and complete a latency profiling for each sub-component, including the video codec and the Wi-Fi links. Furthermore, we provide guidelines for practical design choices including the optimal configuration of the scanning process during handoffs and the codec parameters for delay optimization. Overall, our proposed configuration reduces the end-to-end delay significantly in comparison with the default configuration.}, keywords = {Electrical Communications Engineering}, pubstate = {forthcoming}, tppubtype = {conference} } We consider the use of Wi-Fi (IEEE 802.11n/r) network for remote control of a vehicle using video transmission on the uplink and control signals for the actuator on the downlink. We have setup a network with multiple access points (AP) providing indoor and outdoor coverage, which connects an unmanned ground vehicle (UGV) to a remote command center. Additionally, our setup includes a redundant IEEE 802.11p link for sending control messages over downlink with high reliability and low latency. We study the end-to-end communication delay and complete a latency profiling for each sub-component, including the video codec and the Wi-Fi links. Furthermore, we provide guidelines for practical design choices including the optimal configuration of the scanning process during handoffs and the codec parameters for delay optimization. Overall, our proposed configuration reduces the end-to-end delay significantly in comparison with the default configuration. |
| 24. | Subhajit Goswami; Pavankumar, Tallapragada One-Shot Coordination of First and Last Mode for Multi-Modal Transportation Journal Article arXiv:2001.01283, 2020. Abstract | BibTeX | Tags: Electrical Engineering | Links: @article{@Subhajitb, title = {One-Shot Coordination of First and Last Mode for Multi-Modal Transportation}, author = {Subhajit Goswami; Pavankumar, Tallapragada}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/One-Shot-Coordination-of-First-and-Last-Mode-for-Multi-Modal-Transport.pdf}, year = {2020}, date = {2020-01-05}, journal = {arXiv:2001.01283}, abstract = {In this paper, we consider coordinated control of feeder vehicles for the first and last mode of a multi-modal transportation system. We adopt a macroscopic approach and model a geographical region as a graph with one of the nodes being an interchange between different modes of transportation. We model customer demands and supplies of vehicles as volumes and consider flows of vehicles. We propose one-shot problems for passenger transportation to or from the interchange within a fixed time window, under the knowledge of the demand distribution. In particular, we pose the problem of operator profit maximization through routing and allocations of the vehicles as well as pricing. With K.K.T. analysis we propose an offline method for reducing the problem size. Further, we also analyse the problem of maximizing profits by optimally locating the supply for a given total supply and present a closed form expression of the maximum profits that can be earned over all supply distributions for a given demand distribution. We also show an equivalence between optimal supply location problem and the last mode problem. Finally we present a model for determining the comparative cost of the best alternate transportation for the feeder service to be viable. We illustrate the results through simulations and also compare the proposed model with a traditional vehicle routing problem.}, keywords = {Electrical Engineering}, pubstate = {published}, tppubtype = {article} } In this paper, we consider coordinated control of feeder vehicles for the first and last mode of a multi-modal transportation system. We adopt a macroscopic approach and model a geographical region as a graph with one of the nodes being an interchange between different modes of transportation. We model customer demands and supplies of vehicles as volumes and consider flows of vehicles. We propose one-shot problems for passenger transportation to or from the interchange within a fixed time window, under the knowledge of the demand distribution. In particular, we pose the problem of operator profit maximization through routing and allocations of the vehicles as well as pricing. With K.K.T. analysis we propose an offline method for reducing the problem size. Further, we also analyse the problem of maximizing profits by optimally locating the supply for a given total supply and present a closed form expression of the maximum profits that can be earned over all supply distributions for a given demand distribution. We also show an equivalence between optimal supply location problem and the last mode problem. Finally we present a model for determining the comparative cost of the best alternate transportation for the feeder service to be viable. We illustrate the results through simulations and also compare the proposed model with a traditional vehicle routing problem. |
| 25. | Ashok Krishnan KS; Chandramani Singh; Siva Theja Maguluri; Parimal, Parag Optimal Pricing in Finite Server Systems Conference The 18th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt 2020), 2020. Abstract | BibTeX | Tags: Centre for Networked Intelligence | Links: @conference{@Ashok, title = {Optimal Pricing in Finite Server Systems}, author = {Ashok Krishnan KS; Chandramani Singh; Siva Theja Maguluri; Parimal, Parag}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/08/Optimal-Pricing-in-Finite-Server-Systems.pdf}, year = {2020}, date = {2020-06-15}, booktitle = {The 18th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt 2020)}, abstract = {We consider a system ofKservers, where customersarrive according to a Poisson process, and have independentand identical (i.i.d.) exponential service times andi.i.d.valuationsof the service. We consider the setting where customers leavewhen they find all servers busy. Service provider announces aprice to an incoming customer, depending on the number of busyservers. An incoming arrival enters the system if its valuationexceeds the price. We find the optimal state dependent pricing,that maximizes the revenue rate for the service provider.}, keywords = {Centre for Networked Intelligence}, pubstate = {published}, tppubtype = {conference} } We consider a system ofKservers, where customersarrive according to a Poisson process, and have independentand identical (i.i.d.) exponential service times andi.i.d.valuationsof the service. We consider the setting where customers leavewhen they find all servers busy. Service provider announces aprice to an incoming customer, depending on the number of busyservers. An incoming arrival enters the system if its valuationexceeds the price. We find the optimal state dependent pricing,that maximizes the revenue rate for the service provider. |
| 26. | Sarat Chandra Bobbili; Parimal Parag; Jean-Francois, Chamberland Real-Time Status Updates with Perfect Feedback over Erasure Channels Journal Article IEEE Transactions on Communications , pp. 1-1, 2020. Abstract | BibTeX | Tags: Centre for Networked Intelligence | Links: @article{@Sarat, title = {Real-Time Status Updates with Perfect Feedback over Erasure Channels}, author = {Sarat Chandra Bobbili; Parimal Parag; Jean-Francois,Chamberland}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/08/Real-Time-Status-Updates-with-Perfect-Feedback.pdf}, doi = {10.1109/TCOMM.2020.3006224}, year = {2020}, date = {2020-07-01}, journal = {IEEE Transactions on Communications }, pages = {1-1}, abstract = {Real-time decision making relies on the availability of accurate data and, therefore, delivering status updates in a timely fashion is of paramount importance. The topic of realtime status updates has received much attention in recent years. This article contributes new results to this research area by studying the interplay between average timeliness and design decisions made at the physical layer, for unreliable communication channels. Specifically, this study explores the tension between the fact that more reliable transmissions with lower probabilities of decoding failure tend to improve timely delivery, unless these improvements come at the expense of significantly longer codewords. The average timeliness is adopted as an evaluation criterion, and a framework to efficiently compute the performance of various transmission schemes for the binary erasure channel is developed. We show that the average timeliness decreases as we increase the feedback rate in a hybrid ARQ scheme for a range of codeword lengths. This article also provides design guidelines for the codeword length selection for an hybrid ARQ scheme to improve the average information timeliness. Numerical examples are included to further illustrate the applicability of our findings.}, keywords = {Centre for Networked Intelligence}, pubstate = {published}, tppubtype = {article} } Real-time decision making relies on the availability of accurate data and, therefore, delivering status updates in a timely fashion is of paramount importance. The topic of realtime status updates has received much attention in recent years. This article contributes new results to this research area by studying the interplay between average timeliness and design decisions made at the physical layer, for unreliable communication channels. Specifically, this study explores the tension between the fact that more reliable transmissions with lower probabilities of decoding failure tend to improve timely delivery, unless these improvements come at the expense of significantly longer codewords. The average timeliness is adopted as an evaluation criterion, and a framework to efficiently compute the performance of various transmission schemes for the binary erasure channel is developed. We show that the average timeliness decreases as we increase the feedback rate in a hybrid ARQ scheme for a range of codeword lengths. This article also provides design guidelines for the codeword length selection for an hybrid ARQ scheme to improve the average information timeliness. Numerical examples are included to further illustrate the applicability of our findings. |
| 27. | Gayathri R Prabhu; Srikrishna Bhashyam; Aditya Gopalan, Rajesh Sundaresan Sequential Multi-hypothesis Testing in Multi-armed Bandit Problems: An Approach for Asymptotic Optimality Journal Article arXiv:2007.12961, 2020. Abstract | BibTeX | Tags: Information Theory | Links: @article{@Gayathrib, title = {Sequential Multi-hypothesis Testing in Multi-armed Bandit Problems: An Approach for Asymptotic Optimality}, author = {Gayathri R Prabhu; Srikrishna Bhashyam; Aditya Gopalan, Rajesh Sundaresan}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Sequential-Multi-hypothesis-Testing-in-Multi-armed-Bandit-Problems-An-Approach-for-Asymptotic-Optimality.pdf}, year = {2020}, date = {2020-07-28}, journal = {arXiv:2007.12961}, abstract = {We consider a multi-hypothesis testing problem involving a K-armed bandit. Each arm's signal follows a distribution from a vector exponential family. The actual parameters of the arms are unknown to the decision maker. The decision maker incurs a delay cost for delay until a decision and a switching cost whenever he switches from one arm to another. His goal is to minimise the overall cost until a decision is reached on the true hypothesis. Of interest are policies that satisfy a given constraint on the probability of false detection. This is a sequential decision making problem where the decision maker gets only a limited view of the true state of nature at each stage, but can control his view by choosing the arm to observe at each stage. An information-theoretic lower bound on the total cost (expected time for a reliable decision plus total switching cost) is first identified, and a variation on a sequential policy based on the generalised likelihood ratio statistic is then studied. Due to the vector exponential family assumption, the signal processing at each stage is simple; the associated conjugate prior distribution on the unknown model parameters enables easy updates of the posterior distribution. The proposed policy, with a suitable threshold for stopping, is shown to satisfy the given constraint on the probability of false detection. Under a continuous selection assumption, the policy is also shown to be asymptotically optimal in terms of the total cost among all policies that satisfy the constraint on the probability of false detection. }, keywords = {Information Theory}, pubstate = {published}, tppubtype = {article} } We consider a multi-hypothesis testing problem involving a K-armed bandit. Each arm's signal follows a distribution from a vector exponential family. The actual parameters of the arms are unknown to the decision maker. The decision maker incurs a delay cost for delay until a decision and a switching cost whenever he switches from one arm to another. His goal is to minimise the overall cost until a decision is reached on the true hypothesis. Of interest are policies that satisfy a given constraint on the probability of false detection. This is a sequential decision making problem where the decision maker gets only a limited view of the true state of nature at each stage, but can control his view by choosing the arm to observe at each stage. An information-theoretic lower bound on the total cost (expected time for a reliable decision plus total switching cost) is first identified, and a variation on a sequential policy based on the generalised likelihood ratio statistic is then studied. Due to the vector exponential family assumption, the signal processing at each stage is simple; the associated conjugate prior distribution on the unknown model parameters enables easy updates of the posterior distribution. The proposed policy, with a suitable threshold for stopping, is shown to satisfy the given constraint on the probability of false detection. Under a continuous selection assumption, the policy is also shown to be asymptotically optimal in terms of the total cost among all policies that satisfy the constraint on the probability of false detection. |
| 28. | Rajashekhar, VS; Rokesh Laishram; Kaushik Das; Debasish Ghose Synthesis of a Six-Bar Gripper Mechanism for Aerial Grasping Conference Mohammad Bin Zayed International Robotics Competition (MBZIRC) Symposium, 2020. Abstract | BibTeX | Tags: MBZIRC @conference{@Rajashekar, title = {Synthesis of a Six-Bar Gripper Mechanism for Aerial Grasping}, author = {Rajashekhar, VS; Rokesh Laishram; Kaushik Das; Debasish Ghose}, year = {2020}, date = {2020-03-24}, booktitle = {Mohammad Bin Zayed International Robotics Competition (MBZIRC) Symposium}, abstract = {In this paper, a 1-DoF gripper mechanism has been synthesized for the type of mechanism, number of links and joints, and the dimensions of length, width and thickness of links. The type synthesis is done by selecting the proper class of mechanism from Reuleaux's six classes of mechanisms. The number synthesis is done by using an algebric method. The dimensions of the linkages are found using the geometric programming method. The gripper is then modelled in a computer aided design software and then fabricated using an additive manufacturing technique. Finally the gripper mechanism with DC motor as an actuator is mounted on an Unmanned Aerial Vehicle (UAV) to grip a spherical object moving in space. This work is related to a task in challenge 1 of Mohamed Bin Zayed International Robotics Challenge (MBZIRC)-2020.}, keywords = {MBZIRC}, pubstate = {published}, tppubtype = {conference} } In this paper, a 1-DoF gripper mechanism has been synthesized for the type of mechanism, number of links and joints, and the dimensions of length, width and thickness of links. The type synthesis is done by selecting the proper class of mechanism from Reuleaux's six classes of mechanisms. The number synthesis is done by using an algebric method. The dimensions of the linkages are found using the geometric programming method. The gripper is then modelled in a computer aided design software and then fabricated using an additive manufacturing technique. Finally the gripper mechanism with DC motor as an actuator is mounted on an Unmanned Aerial Vehicle (UAV) to grip a spherical object moving in space. This work is related to a task in challenge 1 of Mohamed Bin Zayed International Robotics Challenge (MBZIRC)-2020. |
| 29. | Aashay Bhise; Shuvrangshu Jana; Lima Agnel Tony; Debasish, Ghose Target State Estimation and Prediction for High Speed Interception Conference Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February, 2020., 2020. Abstract | BibTeX | Tags: MBZIRC | Links: @conference{@Aashay, title = {Target State Estimation and Prediction for High Speed Interception}, author = {Aashay Bhise; Shuvrangshu Jana; Lima Agnel Tony; Debasish, Ghose}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Target-State-Estimation-and-Prediction-for-High-Speed.pdf}, year = {2020}, date = {2020-02-27}, booktitle = {Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February, 2020.}, abstract = {Accurate estimation and prediction of trajectory is essential for interception of any high speed target. In this paper, an extended Kalman filter is used to estimate the current location of target from its visual information and then predict its future position by using the observation sequence. Target motion model is developed considering the approximate known pattern of the target trajectory. In this work, we utilise visual information of the target to carry out the predictions. The proposed algorithm is developed in ROS-Gazebo environment and is verified using hardware implementation.}, keywords = {MBZIRC}, pubstate = {published}, tppubtype = {conference} } Accurate estimation and prediction of trajectory is essential for interception of any high speed target. In this paper, an extended Kalman filter is used to estimate the current location of target from its visual information and then predict its future position by using the observation sequence. Target motion model is developed considering the approximate known pattern of the target trajectory. In this work, we utilise visual information of the target to carry out the predictions. The proposed algorithm is developed in ROS-Gazebo environment and is verified using hardware implementation. |
| 30. | Sagar Gubbi Venkatesh; Raviteja Upadrashta; Shishir Nadubettu Yadukumar; Bharadwaj, Amrutur Teaching Robots Novel Objects by Pointing at Them Conference 29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN), 2020. Abstract | BibTeX | Tags: Robotics | Links: @conference{@Sagarc, title = {Teaching Robots Novel Objects by Pointing at Them}, author = {Sagar Gubbi Venkatesh; Raviteja Upadrashta; Shishir Nadubettu Yadukumar; Bharadwaj, Amrutur}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Teaching-Robots-Novel-Objects-by-Pointing-at-Them.pdf}, year = {2020}, date = {2020-09-10}, booktitle = {29th IEEE International Conference on Robot and Human Interactive Communication (RO-MAN)}, abstract = {Robots that must operate in novel environments and collaborate with humans must be capable of acquiring new knowledge from human experts during operation. We propose teaching a robot novel objects it has not encountered before by pointing a hand at the new object of interest. An end-to end neural network is used to attend to the novel object of interest indicated by the pointing hand and then to localize the object in new scenes. In order to attend to the novel object indicated by the pointing hand, we propose a spatial attention modulation mechanism that learns to focus on the highlighted object while ignoring the other objects in the scene. We show that a robot arm can manipulate novel objects that are highlighted by pointing a hand at them. We also evaluate the performance of the proposed architecture on a synthetic dataset constructed using emojis and on a real-world dataset of common objects.}, keywords = {Robotics}, pubstate = {published}, tppubtype = {conference} } Robots that must operate in novel environments and collaborate with humans must be capable of acquiring new knowledge from human experts during operation. We propose teaching a robot novel objects it has not encountered before by pointing a hand at the new object of interest. An end-to end neural network is used to attend to the novel object of interest indicated by the pointing hand and then to localize the object in new scenes. In order to attend to the novel object indicated by the pointing hand, we propose a spatial attention modulation mechanism that learns to focus on the highlighted object while ignoring the other objects in the scene. We show that a robot arm can manipulate novel objects that are highlighted by pointing a hand at them. We also evaluate the performance of the proposed architecture on a synthetic dataset constructed using emojis and on a real-world dataset of common objects. |
| 31. | Rooji Jinan; Parimal Parag; Himanshu, Tyagi Tracking an Auto-Regressive Process with Limited Communication Journal Article 2020 IEEE International Symposium on Information Theory, 2020. Abstract | BibTeX | Tags: Centre for Networked Intelligence | Links: @article{@Rooji, title = {Tracking an Auto-Regressive Process with Limited Communication }, author = {Rooji Jinan; Parimal Parag; Himanshu, Tyagi}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/08/Tracking-an-Auto-Regressive-Process-with-Limited-Communication-per-Unit-Time.pdf}, year = {2020}, date = {2020-03-22}, journal = {2020 IEEE International Symposium on Information Theory}, abstract = {Samples from a high-dimensional AR[1] process are observed by a sender which can communicate only finitely many bits per unit time to a receiver. The receiver seeks to form an estimate of the process value at every time instant in real-time. We consider a time-slotted communication model in a slow-sampling regime where multiple communication slots occur between two sampling instants. We propose a successive update scheme which uses communication between sampling instants to refine estimates of the latest sample and study the following question: Is it better to collect communication of multiple slots to send better refined estimates, making the receiver wait more for every refinement, or to be fast but loose and send new information in every communication opportunity? We show that the fast but loose successive update scheme with ideal spherical codes is universally optimal asymptotically for a large dimension. However, most practical quantization codes for fixed dimensions do not meet the ideal performance required for this optimality, and they typically will have a bias in the form of a fixed additive error. Interestingly, our analysis shows that the fast but loose scheme is not an optimal choice in the presence of such errors, and a judiciously chosen frequency of updates outperforms it.}, keywords = {Centre for Networked Intelligence}, pubstate = {published}, tppubtype = {article} } Samples from a high-dimensional AR[1] process are observed by a sender which can communicate only finitely many bits per unit time to a receiver. The receiver seeks to form an estimate of the process value at every time instant in real-time. We consider a time-slotted communication model in a slow-sampling regime where multiple communication slots occur between two sampling instants. We propose a successive update scheme which uses communication between sampling instants to refine estimates of the latest sample and study the following question: Is it better to collect communication of multiple slots to send better refined estimates, making the receiver wait more for every refinement, or to be fast but loose and send new information in every communication opportunity? We show that the fast but loose successive update scheme with ideal spherical codes is universally optimal asymptotically for a large dimension. However, most practical quantization codes for fixed dimensions do not meet the ideal performance required for this optimality, and they typically will have a bias in the form of a fixed additive error. Interestingly, our analysis shows that the fast but loose scheme is not an optimal choice in the presence of such errors, and a judiciously chosen frequency of updates outperforms it. |
| 32. | Rooji Jinan Parimal Parag, Himanshu Tyagi Tracking an Auto-Regressive Process with Limited Communication per Unit Time Journal Article arXiv:2003.09808, 2020. Abstract | BibTeX | Tags: Electrical Communications Engineering | Links: @article{@Roojib, title = {Tracking an Auto-Regressive Process with Limited Communication per Unit Time}, author = {Rooji Jinan Parimal Parag, Himanshu Tyagi }, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Tracking-an-Auto-Regressive-Process-with-Limited-Communication-per-Unit-time.pdf}, year = {2020}, date = {2020-03-22}, journal = {arXiv:2003.09808}, abstract = {Samples from a high-dimensional AR[1] process are observed by a sender which can communicate only finitely many bits per unit time to a receiver. The receiver seeks to form an estimate of the process value at every time instant in real-time. We consider a time-slotted communication model in a slow-sampling regime where multiple communication slots occur between two sampling instants. We propose a successive update scheme which uses communication between sampling instants to refine estimates of the latest sample and study the following question: Is it better to collect communication of multiple slots to send better refined estimates, making the receiver wait more for every refinement, or to be fast but loose and send new information in every communication opportunity? We show that the fast but loose successive update scheme with ideal spherical codes is universally optimal asymptotically for a large dimension. However, most practical quantization codes for fixed dimensions do not meet the ideal performance required for this optimality, and they typically will have a bias in the form of a fixed additive error. Interestingly, our analysis shows that the fast but loose scheme is not an optimal choice in the presence of such errors, and a judiciously chosen frequency of updates outperforms it.}, keywords = {Electrical Communications Engineering}, pubstate = {published}, tppubtype = {article} } Samples from a high-dimensional AR[1] process are observed by a sender which can communicate only finitely many bits per unit time to a receiver. The receiver seeks to form an estimate of the process value at every time instant in real-time. We consider a time-slotted communication model in a slow-sampling regime where multiple communication slots occur between two sampling instants. We propose a successive update scheme which uses communication between sampling instants to refine estimates of the latest sample and study the following question: Is it better to collect communication of multiple slots to send better refined estimates, making the receiver wait more for every refinement, or to be fast but loose and send new information in every communication opportunity? We show that the fast but loose successive update scheme with ideal spherical codes is universally optimal asymptotically for a large dimension. However, most practical quantization codes for fixed dimensions do not meet the ideal performance required for this optimality, and they typically will have a bias in the form of a fixed additive error. Interestingly, our analysis shows that the fast but loose scheme is not an optimal choice in the presence of such errors, and a judiciously chosen frequency of updates outperforms it. |
| 33. | Lima Agnel Tony; Shuvrangshu Jana; Aashay Bhise; Varun VP; Aruul Mozhi Varman S; Vidyadhara, BV; Mohitvishnu Gadde; Debasish Ghose; Raghu Krishnapuram Vision based Target Interception using Aerial Manipulation Conference Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February, 2020. Abstract | BibTeX | Tags: MBZIRC | Links: @conference{@Limab, title = {Vision based Target Interception using Aerial Manipulation}, author = {Lima Agnel Tony; Shuvrangshu Jana; Aashay Bhise; Varun VP; Aruul Mozhi Varman S; Vidyadhara, BV; Mohitvishnu Gadde; Debasish Ghose; Raghu Krishnapuram}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Vision-based-Target-Interception-using-Aerial-Manipulation.pdf}, year = {2020}, date = {2020-09-28}, booktitle = {Mohammed Bin Zayed International Robotic Challenge, ADNEC, Abu Dhabi, 26-27 February}, abstract = {Selective interception of objects in unknown environment autonomously by UAVs is an interesting problem. In this work, vision based interception is carried out. This problem is a part of challenge 1 of Mohammed Bin Zayed International Robotic Challenge, 2020, where, balloons are kept at five random locations for the UAVs to autonomously explore, detect, approach and intercept. The problem requires a different formulation to execute compared to the normal interception problems in literature. This work details the different aspect of this problem from vision to manipulator design. The frame work is implemented on hardware using Robot Operating System (ROS) communication architecture.}, keywords = {MBZIRC}, pubstate = {published}, tppubtype = {conference} } Selective interception of objects in unknown environment autonomously by UAVs is an interesting problem. In this work, vision based interception is carried out. This problem is a part of challenge 1 of Mohammed Bin Zayed International Robotic Challenge, 2020, where, balloons are kept at five random locations for the UAVs to autonomously explore, detect, approach and intercept. The problem requires a different formulation to execute compared to the normal interception problems in literature. This work details the different aspect of this problem from vision to manipulator design. The frame work is implemented on hardware using Robot Operating System (ROS) communication architecture. |
2019 |
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| 34. | Chakraborty, Atlanta; Chandru, Vijay; Rao, M R A linear programming primer: From Fourier to Karmarkar Journal Article Annals of Operations Research, 2019. Abstract | BibTeX | Tags: Control and Optimisation | Links: @article{Chakraborty2019, title = {A linear programming primer: From Fourier to Karmarkar}, author = {Atlanta Chakraborty and Vijay Chandru and M. R. Rao}, url = {http://www.rbccps.org/wp-content/uploads/2019/03/Chakraborty2019_Article_ALinearProgrammingPrimerFromFo.pdf}, doi = {10.1007/s10479-019-03186-2}, year = {2019}, date = {2019-03-01}, journal = {Annals of Operations Research}, abstract = {The story of linear programming is one with all the elements of a grand historical drama. The original idea of testing if a polyhedron is non-empty by using a variable elimination to project down one dimension at a time until a tautology emerges dates back to a paper by Fourier in 1823. This gets re-invented in the 1930s by Motzkin. The real interest in linear programming happens during World War II when mathematicians ponder best ways of utilising resources at a time when they are constrained. The problem of optimising a linear function over a set of linear inequalities becomes the focus of the effort. Dantzig’s Simplex Method is announced and the Rand Corporation becomes a hot bed of computational mathematics. The range of applications of this modelling approach grows and the powerful machinery of numerical analysis and numerical linear algebra becomes a major driver for the advancement of computing machines. In the 1970s, constructs of theoretical computer science indicate that linear programming may in fact define the frontier of tractable problems that can be solved effectively on large instances. This raised a series of questions and answers: Is the Simplex Method a polynomial-time method and if not can we construct novel polynomial time methods, etc. And that is how the Ellipsoid Method from the Soviet Union and the Interior Point Method from Bell Labs make their way into this story as the heroics of Khachiyan and Karmarkar. We have called this paper a primer on linear programming since it only gives the reader a quick narrative of the grand historical drama. Hopefully it motivates a young reader to delve deeper and add another chapter.}, keywords = {Control and Optimisation}, pubstate = {published}, tppubtype = {article} } The story of linear programming is one with all the elements of a grand historical drama. The original idea of testing if a polyhedron is non-empty by using a variable elimination to project down one dimension at a time until a tautology emerges dates back to a paper by Fourier in 1823. This gets re-invented in the 1930s by Motzkin. The real interest in linear programming happens during World War II when mathematicians ponder best ways of utilising resources at a time when they are constrained. The problem of optimising a linear function over a set of linear inequalities becomes the focus of the effort. Dantzig’s Simplex Method is announced and the Rand Corporation becomes a hot bed of computational mathematics. The range of applications of this modelling approach grows and the powerful machinery of numerical analysis and numerical linear algebra becomes a major driver for the advancement of computing machines. In the 1970s, constructs of theoretical computer science indicate that linear programming may in fact define the frontier of tractable problems that can be solved effectively on large instances. This raised a series of questions and answers: Is the Simplex Method a polynomial-time method and if not can we construct novel polynomial time methods, etc. And that is how the Ellipsoid Method from the Soviet Union and the Interior Point Method from Bell Labs make their way into this story as the heroics of Khachiyan and Karmarkar. We have called this paper a primer on linear programming since it only gives the reader a quick narrative of the grand historical drama. Hopefully it motivates a young reader to delve deeper and add another chapter. |
| 35. | P T, Akhil; Eitan Altman; Rajesh Sundaresan A Mean-field Approach for Controlling Singularly Perturbed Multi-population SIS Epidemics Journal Article arXiv.org: Math, 2019. Abstract | BibTeX | Tags: Control and Optimisation | Links: @article{Akhil2019, title = {A Mean-field Approach for Controlling Singularly Perturbed Multi-population SIS Epidemics}, author = {P T, Akhil; Eitan Altman; Rajesh Sundaresan}, url = {http://10.0.54.4/wp-content/uploads/2019/09/A-mean-fields-approach-for-controlling-singularly-perturbed-multi-population-SIS-Epidemics.pdf}, year = {2019}, date = {2019-02-15}, journal = {arXiv.org: Math}, abstract = {We consider a multi-population epidemic model with one or more (almost) isolated communities and one mobile community. Each of the isolated communities has contact within itself and, in addition, contact with the outside world but only through the mobile community. The contact rate between the mobile community and the other communities is assumed to be controlled. We first derive a multidimensional ordinary differential equation (ODE) as a mean-field fluid approximation to the process of the number of infected nodes, after appropriate scaling. We show that the approximation becomes tight as the sizes of the communities grow. We then use a singular perturbation approach to reduce the dimension of the ODE and identify an optimal control policy on this system over a fixed time horizon via Pontryagin’s minimum principle. We then show that this policy is close to optimal, within a certain class, on the original problem for large enough communities. From a phenomenological perspective, we show that the epidemic may sustain in time in all communities (and thus the system has a nontrivial metastable regime) even though in the absence of the mobile nodes the epidemic would die out quickly within each of the isolated communities.}, keywords = {Control and Optimisation}, pubstate = {published}, tppubtype = {article} } We consider a multi-population epidemic model with one or more (almost) isolated communities and one mobile community. Each of the isolated communities has contact within itself and, in addition, contact with the outside world but only through the mobile community. The contact rate between the mobile community and the other communities is assumed to be controlled. We first derive a multidimensional ordinary differential equation (ODE) as a mean-field fluid approximation to the process of the number of infected nodes, after appropriate scaling. We show that the approximation becomes tight as the sizes of the communities grow. We then use a singular perturbation approach to reduce the dimension of the ODE and identify an optimal control policy on this system over a fixed time horizon via Pontryagin’s minimum principle. We then show that this policy is close to optimal, within a certain class, on the original problem for large enough communities. From a phenomenological perspective, we show that the epidemic may sustain in time in all communities (and thus the system has a nontrivial metastable regime) even though in the absence of the mobile nodes the epidemic would die out quickly within each of the isolated communities. |
| 36. | Kuraganti Chetan Kumar; Gurunath Gurrala; Rajesh, Sundaresan A Sequential Testing Framework for Identifying a Transmission Line Outage in a Power System Conference e-Energy '19 Proceedings of the Tenth ACM International Conference on Future Energy Systems, June 25 - 28, 2019, Phoenix, AZ, USA, 2019. Abstract | BibTeX | Tags: Smart Grid | Links: @conference{@Chetan2019, title = {A Sequential Testing Framework for Identifying a Transmission Line Outage in a Power System}, author = {Kuraganti Chetan Kumar; Gurunath Gurrala; Rajesh,Sundaresan}, url = {http://10.0.54.4/wp-content/uploads/2019/10/A-Sequential-Testing-Framework-for-Identifying-a-Transmission-Line-Outage-in-a-Power-System.pdf}, doi = {10.1145/3307772.3328297}, year = {2019}, date = {2019-06-15}, booktitle = {e-Energy '19 Proceedings of the Tenth ACM International Conference on Future Energy Systems, June 25 - 28, 2019, Phoenix, AZ, USA}, pages = {331-342}, abstract = {The topology of a power system changes when a line outage is encountered. Identifying which line has failed in the shortest possible time is of importance due to the cascading nature of such failures. In this work, we propose a state estimation based sequential hypothesis testing procedure to locate the failed line. We focus on single line outages as these are the most frequently occurring failures. Earlier work on state estimation based sequential testing procedure used a DC approximation model assuming that the sensors provided angle and voltage information. This is known to be a coarse model but results in a simpler linear estimation problem. In this work, we look at a finer nonlinear model of power measurements and treat phase angles and voltages as hidden states. After a local linearization, we propose a Kalman filter based state estimation followed by a generalized likelihood ratio testing procedure to determine which of the lines has failed. We consider both centralized and decentralized approaches. In the centralized case, measurements from every installed meter is made available to the system operator. In the decentralized case, only limited aggregated information is made available because of, for example, communication capacity constraints. We test our algorithms on the IEEE 14 and 118 bus systems and show that all high risk link failures are quickly identified.}, keywords = {Smart Grid}, pubstate = {published}, tppubtype = {conference} } The topology of a power system changes when a line outage is encountered. Identifying which line has failed in the shortest possible time is of importance due to the cascading nature of such failures. In this work, we propose a state estimation based sequential hypothesis testing procedure to locate the failed line. We focus on single line outages as these are the most frequently occurring failures. Earlier work on state estimation based sequential testing procedure used a DC approximation model assuming that the sensors provided angle and voltage information. This is known to be a coarse model but results in a simpler linear estimation problem. In this work, we look at a finer nonlinear model of power measurements and treat phase angles and voltages as hidden states. After a local linearization, we propose a Kalman filter based state estimation followed by a generalized likelihood ratio testing procedure to determine which of the lines has failed. We consider both centralized and decentralized approaches. In the centralized case, measurements from every installed meter is made available to the system operator. In the decentralized case, only limited aggregated information is made available because of, for example, communication capacity constraints. We test our algorithms on the IEEE 14 and 118 bus systems and show that all high risk link failures are quickly identified. |
| 37. | Karanjkar, Neha; Tejasvi, Poorna Chandra; Amrutur, Bharadwaj A simpy-based simulation testbed Presentation 18.04.2019. Abstract | BibTeX | Tags: Smart City | Links: @misc{Karanjkar2019, title = {A simpy-based simulation testbed }, author = {Neha Karanjkar and Poorna Chandra Tejasvi and Bharadwaj Amrutur}, doi = {10.1145/3302505.3312591}, year = {2019}, date = {2019-04-18}, abstract = {A real-time testbed that emulates a large number of IoT end-points generating traffic to the middleware/application layers can be used for debugging and performance evaluation of the smart-city software platforms prior to deployment. We propose an architecture for such a simulation testbed based on Python's SimPy library. The simulated IoT end-points communicate with the middleware in real-time and can also interact directly with each other and with a common shared environment. This makes the testbed particularly suited for modeling system-wide scenarios such as synchronized faults and power outages.}, keywords = {Smart City}, pubstate = {published}, tppubtype = {presentation} } A real-time testbed that emulates a large number of IoT end-points generating traffic to the middleware/application layers can be used for debugging and performance evaluation of the smart-city software platforms prior to deployment. We propose an architecture for such a simulation testbed based on Python's SimPy library. The simulated IoT end-points communicate with the middleware in real-time and can also interact directly with each other and with a common shared environment. This makes the testbed particularly suited for modeling system-wide scenarios such as synchronized faults and power outages. |
| 38. | Rokesh Laishram; Bisheshwar H; Shivakumar N D; Bharadwaj Amrutur; T Y, Reddy A Study on the Effects of Fiber Orientation on Woven Glass Fiber Composite Structures Conference Proceedings of The 2nd International Conference on Research in Science, Engineering, and Technology, 2019. Abstract | BibTeX | Tags: Multiagent Systems | Links: @conference{@Rokesh, title = {A Study on the Effects of Fiber Orientation on Woven Glass Fiber Composite Structures}, author = {Rokesh Laishram; Bisheshwar,H; Shivakumar N D; Bharadwaj Amrutur; T Y, Reddy}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/09/A-Study-on-the-Effects-of-Fiber-Orientation-on-Woven-Glass-Fiber-Composite-Structures.pdf}, doi = {https://www.doi.org/10.33422/2nd.rsetconf.2019.09.619}, year = {2019}, date = {2019-03-01}, booktitle = {Proceedings of The 2nd International Conference on Research in Science, Engineering, and Technology}, abstract = {Scholars have studied hybrid composites for decades in the search of finding some good outcome which could be used for different purposes. The present study is focused on studying the effects of fiber orientation through mechanical testing on coupons made according to ASTM standards and through dropped weight test on tubes made of the same configuration. Initially, the tensile experiments of laminas; normal [0/90] and oriented [+45/45] are conducted as a preliminary study and a distinctive behaviour could be seen. The oriented one shows low tensile strength and low modulus but very high failure strains while the other one having high tensile strength and modulus but low failure strain. In the laminate of 3 plies [(0/90)3] and [(0/90)/(+45/-45)/(0/90)], upon comparing the results, it is found that the tensile and compressive stress-strain results are almost similar but the shear experimental result shows some interesting behaviour due to the addition of a (+45/-45)ply in the middle of the later laminate. Axial Dropped weight tests on circular tubes made of the same configuration are also conducted for comparing the energy absorption characteristics and failure behaviours. }, keywords = {Multiagent Systems}, pubstate = {published}, tppubtype = {conference} } Scholars have studied hybrid composites for decades in the search of finding some good outcome which could be used for different purposes. The present study is focused on studying the effects of fiber orientation through mechanical testing on coupons made according to ASTM standards and through dropped weight test on tubes made of the same configuration. Initially, the tensile experiments of laminas; normal [0/90] and oriented [+45/45] are conducted as a preliminary study and a distinctive behaviour could be seen. The oriented one shows low tensile strength and low modulus but very high failure strains while the other one having high tensile strength and modulus but low failure strain. In the laminate of 3 plies [(0/90)3] and [(0/90)/(+45/-45)/(0/90)], upon comparing the results, it is found that the tensile and compressive stress-strain results are almost similar but the shear experimental result shows some interesting behaviour due to the addition of a (+45/-45)ply in the middle of the later laminate. Axial Dropped weight tests on circular tubes made of the same configuration are also conducted for comparing the energy absorption characteristics and failure behaviours. |
| 39. | Raghuram Bharadwaj Diddigi ; D Sai Koti Reddy ; K J, Prabhuchandran ;Shalabh Bhatnagar Actor-Critic Algorithms for Constrained Multi-agent Reinforcement Learning Conference AAMAS 19, Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems, 2019, ISBN: 978-1-4503-6309-9. Abstract | BibTeX | Tags: Multiagent Systems | Links: @conference{Raghuram2019, title = {Actor-Critic Algorithms for Constrained Multi-agent Reinforcement Learning}, author = {Raghuram Bharadwaj Diddigi ; D, Sai Koti Reddy ; K J, Prabhuchandran ;Shalabh Bhatnagar}, url = {http://10.0.54.4/wp-content/uploads/2019/09/Actor-Critic-Algorithms-for-Constrained-multi-agent-Reinforcement-Learning.pdf}, isbn = {978-1-4503-6309-9}, year = {2019}, date = {2019-05-08}, booktitle = {AAMAS 19, Proceedings of the 18th International Conference on Autonomous Agents and MultiAgent Systems}, journal = {AAMAS (International Conference on Autonomous Agents and Multiagent Systems)}, pages = {1931-1933 }, abstract = {Multi-agent reinforcement learning has gained lot of popularity primarily owing to the success of deep function approximation architectures. However, many real-life multi-agent applications often impose constraints on the joint action sequence that can be taken by the agents. In this work, we formulate such problems in the framework of constrained cooperative stochastic games. Under this setting, the goal of the agents is to obtain joint action sequence that minimizes a total cost objective criterion subject to total cost penalty/budget functional constraints. To this end, we utilize the Lagrangian formulation and propose actor-critic algorithms. Through experiments on a constrained multi-agent grid world task, we demonstrate that our algorithms converge to near-optimal joint action sequences satisfying the given constraints.}, keywords = {Multiagent Systems}, pubstate = {published}, tppubtype = {conference} } Multi-agent reinforcement learning has gained lot of popularity primarily owing to the success of deep function approximation architectures. However, many real-life multi-agent applications often impose constraints on the joint action sequence that can be taken by the agents. In this work, we formulate such problems in the framework of constrained cooperative stochastic games. Under this setting, the goal of the agents is to obtain joint action sequence that minimizes a total cost objective criterion subject to total cost penalty/budget functional constraints. To this end, we utilize the Lagrangian formulation and propose actor-critic algorithms. Through experiments on a constrained multi-agent grid world task, we demonstrate that our algorithms converge to near-optimal joint action sequences satisfying the given constraints. |
| 40. | Jogendra Nath Kundu; Maharshi Gor; R, Venkatesh Babu BiHMP-GAN: Bidirectional 3D Human Motion Prediction GAN Conference Proceedings of the Thirty-Third AAAI Conference on Artificial Intelligence, 33 , 2019. Abstract | BibTeX | Tags: Student Research Grant | Links: @conference{Jogendra2019, title = {BiHMP-GAN: Bidirectional 3D Human Motion Prediction GAN}, author = {Jogendra Nath Kundu; Maharshi Gor; R, Venkatesh Babu}, url = {http://10.0.54.4/wp-content/uploads/2019/09/BiHMP-GAN-Bidirectional-3D-human-motion-Prediction-GAN.pdf}, doi = {10.1609/aaai.v33i01.33018553}, year = {2019}, date = {2019-07-17}, booktitle = {Proceedings of the Thirty-Third AAAI Conference on Artificial Intelligence}, volume = {33}, abstract = {Human motion prediction model has applications in various fields of computer vision. Without taking into account the inherent stochasticity in the prediction of future pose dynamics, such methods often converges to a deterministic undesired mean of multiple probable outcomes. Devoid of this, we propose a novel probabilistic generative approach called Bidirectional Human motion prediction GAN, or BiHMP-GAN. To be able to generate multiple probable human-pose sequences, conditioned on a given starting sequence, we introduce a random extrinsic factor r, drawn from a predefined prior distribution. Furthermore, to enforce a direct content loss on the predicted motion sequence and also to avoid mode-collapse, a novel bidirectional framework is incorporated by modifying the usual discriminator architecture. The discriminator is trained also to regress this extrinsic factor r, which is used alongside with the intrinsic factor (encoded starting pose sequence) to generate a particular pose sequence. To further regularize the training, we introduce a novel recursive prediction strategy. In spite of being in a probabilistic framework, the enhanced discriminator architecture allows predictions of an intermediate part of pose sequence to be used as a conditioning for prediction of the latter part of the sequence. The bidirectional setup also provides a new direction to evaluate the prediction quality against a given test sequence. For a fair assessment of BiHMP-GAN, we report performance of the generated motion sequence using (i) a critic model trained to discriminate between real and fake motion sequence, and (ii) an action classifier trained on real human motion dynamics. Outcomes of both qualitative and quantitative evaluations, on the probabilistic generations of the model, demonstrate the superiority of BiHMP-GAN over previously available methods.}, keywords = {Student Research Grant}, pubstate = {published}, tppubtype = {conference} } Human motion prediction model has applications in various fields of computer vision. Without taking into account the inherent stochasticity in the prediction of future pose dynamics, such methods often converges to a deterministic undesired mean of multiple probable outcomes. Devoid of this, we propose a novel probabilistic generative approach called Bidirectional Human motion prediction GAN, or BiHMP-GAN. To be able to generate multiple probable human-pose sequences, conditioned on a given starting sequence, we introduce a random extrinsic factor r, drawn from a predefined prior distribution. Furthermore, to enforce a direct content loss on the predicted motion sequence and also to avoid mode-collapse, a novel bidirectional framework is incorporated by modifying the usual discriminator architecture. The discriminator is trained also to regress this extrinsic factor r, which is used alongside with the intrinsic factor (encoded starting pose sequence) to generate a particular pose sequence. To further regularize the training, we introduce a novel recursive prediction strategy. In spite of being in a probabilistic framework, the enhanced discriminator architecture allows predictions of an intermediate part of pose sequence to be used as a conditioning for prediction of the latter part of the sequence. The bidirectional setup also provides a new direction to evaluate the prediction quality against a given test sequence. For a fair assessment of BiHMP-GAN, we report performance of the generated motion sequence using (i) a critic model trained to discriminate between real and fake motion sequence, and (ii) an action classifier trained on real human motion dynamics. Outcomes of both qualitative and quantitative evaluations, on the probabilistic generations of the model, demonstrate the superiority of BiHMP-GAN over previously available methods. |
| 41. | K L Navaneet; Priyanka Mandikal; Mayank Agarwal; R, Venkatesh Babu CAPNet: Continuous Approximation Projection for 3D Point Cloud Reconstruction Using 2D Supervision Conference Proceedings of the AAAI Conference on Artificial Intelligence, 33 , 2019. Abstract | BibTeX | Tags: Student Research Grant | Links: @conference{Navaneet2019, title = {CAPNet: Continuous Approximation Projection for 3D Point Cloud Reconstruction Using 2D Supervision}, author = {K L, Navaneet; Priyanka Mandikal; Mayank Agarwal; R, Venkatesh Babu}, url = {http://10.0.54.4/wp-content/uploads/2019/09/Capnet-Continuous-Approximation-projection-for-3D-point-Cloud-Reconstruction-using-2D-Supervision.pdf}, doi = {10.1609/aaai.v33i01.33018819}, year = {2019}, date = {2019-07-17}, booktitle = {Proceedings of the AAAI Conference on Artificial Intelligence}, volume = {33}, pages = {8819-8826}, abstract = {Knowledge of 3D properties of objects is a necessity in order to build effective computer vision systems. However, lack of large scale 3D datasets can be a major constraint for datadriven approaches in learning such properties. We consider the task of single image 3D point cloud reconstruction, and aim to utilize multiple foreground masks as our supervisory data to alleviate the need for large scale 3D datasets. A novel differentiable projection module, called ‘CAPNet’, is introduced to obtain such 2D masks from a predicted 3D point cloud. The key idea is to model the projections as a continuous approximation of the points in the point cloud. To overcome the challenges of sparse projection maps, we propose a loss formulation termed ‘affinity loss’ to generate outlierfree reconstructions. We significantly outperform the existing projection based approaches on a large-scale synthetic dataset. We show the utility and generalizability of such a 2D supervised approach through experiments on a real-world dataset, where lack of 3D data can be a serious concern. To further enhance the reconstructions, we also propose a test stage optimization procedure to obtain reconstructions that display high correspondence with the observed input image.}, keywords = {Student Research Grant}, pubstate = {published}, tppubtype = {conference} } Knowledge of 3D properties of objects is a necessity in order to build effective computer vision systems. However, lack of large scale 3D datasets can be a major constraint for datadriven approaches in learning such properties. We consider the task of single image 3D point cloud reconstruction, and aim to utilize multiple foreground masks as our supervisory data to alleviate the need for large scale 3D datasets. A novel differentiable projection module, called ‘CAPNet’, is introduced to obtain such 2D masks from a predicted 3D point cloud. The key idea is to model the projections as a continuous approximation of the points in the point cloud. To overcome the challenges of sparse projection maps, we propose a loss formulation termed ‘affinity loss’ to generate outlierfree reconstructions. We significantly outperform the existing projection based approaches on a large-scale synthetic dataset. We show the utility and generalizability of such a 2D supervised approach through experiments on a real-world dataset, where lack of 3D data can be a serious concern. To further enhance the reconstructions, we also propose a test stage optimization procedure to obtain reconstructions that display high correspondence with the observed input image. |
| 42. | Gayarthi, H; Gulhare, Siddhartha; Verma, Ashish Characteristics of stop and go wave in one dimensional interrupted pedestrian flow through narrow channel Journal Article Collective Dynamics, pp. A18:1-14, 2019. Abstract | BibTeX | Tags: The Kumbh Mela Experiment | Links: @article{Gayarthi2019, title = {Characteristics of stop and go wave in one dimensional interrupted pedestrian flow through narrow channel}, author = {H. Gayarthi and Siddhartha Gulhare and Ashish Verma}, url = {http://www.rbccps.org/wp-content/uploads/2019/05/34-296-1-PB.pdf}, doi = {10.17815/CD.2018.18}, year = {2019}, date = {2019-01-12}, journal = {Collective Dynamics}, pages = {A18:1-14}, abstract = {Pedestrian microscopic simulation models can aid crowd management only if they can reproduce the crowd behavior correctly. To calibrate and validate the model, it is important to understand crowd movement during various activities involved in mass gathering events. A common practice in such gathering is to hold attendees in waiting area in near corridors separated by crowd barriers before the event and allow entering the event only after a designated time. The crowd is released in small batches to avoid overcrowding inside. Long waiting hours, anger, excitement, competitive feeling etc. can make crowd aggressive during such entries. Crowd flow characteristics due to such behavior is difficult to recreate in pedestrian experimental studies in laboratory setting. This paper studied interrupted flow of such crowd through a narrow corridors made of strong railing channel inside a temple. Interrupted flow lead to formation of one dimensional stop and go waves. These stop and go waves were studied from the trajectory data. The average speed of waves propagating over longer distance were also estimated. The quantitative output from this study can be used to calibrate and validate simulation models of such activity during mass gathering events.}, keywords = {The Kumbh Mela Experiment}, pubstate = {published}, tppubtype = {article} } Pedestrian microscopic simulation models can aid crowd management only if they can reproduce the crowd behavior correctly. To calibrate and validate the model, it is important to understand crowd movement during various activities involved in mass gathering events. A common practice in such gathering is to hold attendees in waiting area in near corridors separated by crowd barriers before the event and allow entering the event only after a designated time. The crowd is released in small batches to avoid overcrowding inside. Long waiting hours, anger, excitement, competitive feeling etc. can make crowd aggressive during such entries. Crowd flow characteristics due to such behavior is difficult to recreate in pedestrian experimental studies in laboratory setting. This paper studied interrupted flow of such crowd through a narrow corridors made of strong railing channel inside a temple. Interrupted flow lead to formation of one dimensional stop and go waves. These stop and go waves were studied from the trajectory data. The average speed of waves propagating over longer distance were also estimated. The quantitative output from this study can be used to calibrate and validate simulation models of such activity during mass gathering events. |
| 43. | Dholakiya, Dhaivat; Bhattacharya, Shounak; Gunalan, Ajay; Singla, Abhik; Bhatnagar, Shalabh; Amrutur, Bharadwaj; Ghosal, Ashitava; Kolathaya, Shishir Design, development and experimental realization of a quadrupedal research platform: Stoch Journal Article arXiv: Computer Science, 2019. Abstract | BibTeX | Tags: Walking Robot | Links: @article{Dholakiya2019, title = {Design, development and experimental realization of a quadrupedal research platform: Stoch}, author = {Dhaivat Dholakiya and Shounak Bhattacharya and Ajay Gunalan and Abhik Singla and Shalabh Bhatnagar and Bharadwaj Amrutur and Ashitava Ghosal and Shishir Kolathaya}, url = {http://www.rbccps.org/wp-content/uploads/2019/05/1901.00697.pdf}, year = {2019}, date = {2019-01-03}, journal = {arXiv: Computer Science}, abstract = {In this paper, we present a complete description of the hardware design and control architecture of our custom built quadruped robot, called the `Stoch'. Our goal is to realize a robust, modular, and a reliable quadrupedal platform, using which various locomotion behaviors are explored. This platform enables us to explore different research problems in legged locomotion, which use both traditional and learning based techniques. We discuss the merits and limitations of the platform in terms of exploitation of available behaviours, fast rapid prototyping, reproduction and repair. Towards the end, we will demonstrate trotting, bounding behaviors, and preliminary results in turning. In addition, we will also show various gait transitions i.e., trot-to-turn and trot-to-bound behaviors. }, keywords = {Walking Robot}, pubstate = {published}, tppubtype = {article} } In this paper, we present a complete description of the hardware design and control architecture of our custom built quadruped robot, called the `Stoch'. Our goal is to realize a robust, modular, and a reliable quadrupedal platform, using which various locomotion behaviors are explored. This platform enables us to explore different research problems in legged locomotion, which use both traditional and learning based techniques. We discuss the merits and limitations of the platform in terms of exploitation of available behaviours, fast rapid prototyping, reproduction and repair. Towards the end, we will demonstrate trotting, bounding behaviors, and preliminary results in turning. In addition, we will also show various gait transitions i.e., trot-to-turn and trot-to-bound behaviors. |
| 44. | K P, Naveen; Rajesh Sundaresan Double-Auction Mechanisms for Resource Trading Markets Journal Article arXiv: Computer Science, 2019. Abstract | BibTeX | Tags: Networking and Internet Architecture | Links: @article{Naveen2019, title = {Double-Auction Mechanisms for Resource Trading Markets}, author = {K P, Naveen; Rajesh Sundaresan}, url = {http://10.0.54.4/wp-content/uploads/2019/09/Double-auction-Mechanisms-for-resource-trading-markets.pdf}, year = {2019}, date = {2019-01-27}, journal = {arXiv: Computer Science}, abstract = {We consider a double-auction mechanism, which was recently proposed in the context of a mobile data-offloading market. It is also applicable in a network slicing market. Network operators (users) derive benefit from offloading their traffic to third party WiFi or femtocell networks (link-suppliers). Link-suppliers experience costs for the additional capacity that they provide. Users and link-suppliers (collectively referred to as agents) have their pay-offs and cost functions as private knowledge. A system-designer decomposes the problem into a network problem (with surrogate pay-offs and surrogate cost functions) and agent problems (one per agent). The surrogate pay-offs and cost functions are modulated by the agents’ bids. Agents’ payoffs and costs are then determined by the allocations and prices set by the system designer. Under this design, so long as the agents do not anticipate the effect of their actions, a competitive equilibrium exists as a solution to the network and agent problems, and this equilibrium optimizes the system utility. However, this design fails when the agents are strategic (price anticipating). The presence of strategic supplying agents drives the system to an undesirable equilibrium with zero participation resulting in an efficiency loss of 100%. This is in stark contrast to the setting when link-suppliers are not strategic: the efficiency loss is at most 34% when the users alone are strategic. The paper then proposes a Stackelberg game modification with asymmetric information structures for suppliers and users in order to alleviate the efficiency loss problem. The system designer first announces the allocation and payment functions. He then invites the supplying agents to announce their bids, following which the users are invited to respond to the suppliers’ bids. The resulting Stackelberg games efficiency losses can be characterized in terms of the suppliers cost functions when the user pay-off functions are linear. Specifically, when the link-supplier’s cost function is quadratic, the worst case efficiency loss is 25%. Further, the loss in efficiency improves for polynomial cost functions of higher degree.}, keywords = {Networking and Internet Architecture}, pubstate = {published}, tppubtype = {article} } We consider a double-auction mechanism, which was recently proposed in the context of a mobile data-offloading market. It is also applicable in a network slicing market. Network operators (users) derive benefit from offloading their traffic to third party WiFi or femtocell networks (link-suppliers). Link-suppliers experience costs for the additional capacity that they provide. Users and link-suppliers (collectively referred to as agents) have their pay-offs and cost functions as private knowledge. A system-designer decomposes the problem into a network problem (with surrogate pay-offs and surrogate cost functions) and agent problems (one per agent). The surrogate pay-offs and cost functions are modulated by the agents’ bids. Agents’ payoffs and costs are then determined by the allocations and prices set by the system designer. Under this design, so long as the agents do not anticipate the effect of their actions, a competitive equilibrium exists as a solution to the network and agent problems, and this equilibrium optimizes the system utility. However, this design fails when the agents are strategic (price anticipating). The presence of strategic supplying agents drives the system to an undesirable equilibrium with zero participation resulting in an efficiency loss of 100%. This is in stark contrast to the setting when link-suppliers are not strategic: the efficiency loss is at most 34% when the users alone are strategic. The paper then proposes a Stackelberg game modification with asymmetric information structures for suppliers and users in order to alleviate the efficiency loss problem. The system designer first announces the allocation and payment functions. He then invites the supplying agents to announce their bids, following which the users are invited to respond to the suppliers’ bids. The resulting Stackelberg games efficiency losses can be characterized in terms of the suppliers cost functions when the user pay-off functions are linear. Specifically, when the link-supplier’s cost function is quadratic, the worst case efficiency loss is 25%. Further, the loss in efficiency improves for polynomial cost functions of higher degree. |
| 45. | Akshatha, Jagadish; Manoj Varma Enhancing the capture efficiency of a micro-robotic swarm in targeted delivery using velocity control Conference MARSS – Manipulation, Automation and Robotics at Small Scale, 2019. Abstract | BibTeX | Tags: Robot swarms | Links: @conference{Akshatha2019, title = {Enhancing the capture efficiency of a micro-robotic swarm in targeted delivery using velocity control}, author = {Akshatha, Jagadish; Manoj Varma}, url = {http://10.0.54.4/wp-content/uploads/2019/09/Enhancing-the-capture-efficiency-of-a-micro-robotic-swarm-in-targeted-delivery-using-velocity-control.pdf}, year = {2019}, date = {2019-07-05}, booktitle = {MARSS – Manipulation, Automation and Robotics at Small Scale}, journal = {MARSS – Manipulation, Automation and Robotics at Small Scale 2019}, abstract = {Swarm robotics at the micro scale is one of the popular research areas currently. However, there has been no generic approach to modelling, designing and controlling these micro-robotic swarms. In this paper, we investigate the capture efficiency of a micro-robotic swarm for the specific application of targeted delivery. We mathematically model the natural dynamics of the swarm that would help us understand the inherent passive behaviour of the swarm system. This would lead to optimal design and control of the micro-bots. We also investigate the effect of the mean control of the swarm on the capture efficiency, which describes the efficiency of the microrobotic swarm in reaching the target.}, keywords = {Robot swarms}, pubstate = {published}, tppubtype = {conference} } Swarm robotics at the micro scale is one of the popular research areas currently. However, there has been no generic approach to modelling, designing and controlling these micro-robotic swarms. In this paper, we investigate the capture efficiency of a micro-robotic swarm for the specific application of targeted delivery. We mathematically model the natural dynamics of the swarm that would help us understand the inherent passive behaviour of the swarm system. This would lead to optimal design and control of the micro-bots. We also investigate the effect of the mean control of the swarm on the capture efficiency, which describes the efficiency of the microrobotic swarm in reaching the target. |
| 46. | Pavankumar Tallapragada; Massimo Franceschetti; Jorge, Cortes Event-triggered control under time-varying rates and channel blackouts Journal Article {IFAC} Journal of Systems and Control , 9 , 2019. Abstract | BibTeX | Tags: Control and Optimisation, Networked Control systems | Links: @article{@Pavankumar2019b, title = {Event-triggered control under time-varying rates and channel blackouts}, author = {Pavankumar Tallapragada; Massimo Franceschetti; Jorge, Cortes}, url = {http://10.0.54.4/wp-content/uploads/2019/10/Event-tiggered-control-under-time-varying-rates-and-channel-blackouts.pdf}, doi = {10.1016/j.ifacsc.2019.100064}, year = {2019}, date = {2019-09-30}, journal = {{IFAC} Journal of Systems and Control }, volume = {9}, abstract = {This paper studies event-triggered stabilization of linear time-invariant systems over time-varying rate-limited communication channels. We explicitly account for the possibility of channel blackouts, i.e., intervals of time when the communication channel is unavailable for feedback. We assume prior knowledge of the channel evolution and we introduce the notion of bit capacity as the maximum total number of bits that could be communicated over a given time interval. We then provide an efficient real-time algorithm to lower bound the bit capacity for a deterministic channel whose characteristics are piecewise constant in time. Building on these results, we design an event-triggering strategy that guarantees Zeno-free, exponential stabilization at a desired convergence rate even in the presence of intermittent channel blackouts. The contributions are the notion of channel blackouts, the effective event-triggered control despite their occurrence, and the analysis and quantification of the bit capacity for a class of time-varying continuous-time channels. Various simulations illustrate the results.}, keywords = {Control and Optimisation, Networked Control systems}, pubstate = {published}, tppubtype = {article} } This paper studies event-triggered stabilization of linear time-invariant systems over time-varying rate-limited communication channels. We explicitly account for the possibility of channel blackouts, i.e., intervals of time when the communication channel is unavailable for feedback. We assume prior knowledge of the channel evolution and we introduce the notion of bit capacity as the maximum total number of bits that could be communicated over a given time interval. We then provide an efficient real-time algorithm to lower bound the bit capacity for a deterministic channel whose characteristics are piecewise constant in time. Building on these results, we design an event-triggering strategy that guarantees Zeno-free, exponential stabilization at a desired convergence rate even in the presence of intermittent channel blackouts. The contributions are the notion of channel blackouts, the effective event-triggered control despite their occurrence, and the analysis and quantification of the bit capacity for a class of time-varying continuous-time channels. Various simulations illustrate the results. |
| 47. | Shourya Bose; Pavankumar, Tallapragada Event-Triggered Second Moment Stabilization under Markov Packet Drops Conference 2019 Fifth Indian Control Conference (ICC), 9-11 Jan. 2019, New Delhi, India, 2019. Abstract | BibTeX | Tags: Control and Optimisation, Networked Control systems | Links: @conference{@Shourya2019, title = {Event-Triggered Second Moment Stabilization under Markov Packet Drops}, author = {Shourya Bose; Pavankumar,Tallapragada}, url = {http://10.0.54.4/wp-content/uploads/2019/10/Event-triggered-second-moment-stabilization-under-Markov-Packet-drops.pdf}, doi = {10.1109/INDIANCC.2019.8715576}, year = {2019}, date = {2019-05-16}, booktitle = {2019 Fifth Indian Control Conference (ICC), 9-11 Jan. 2019, New Delhi, India}, journal = {Fifth Indian Control Conference (ICC), 9-11 Jan. 2019, New Delhi, India}, pages = {113-118}, abstract = {In this paper, we consider the problem of second moment stabilization of scalar linear systems under Markov packet drops. We assume that the channel state evolution is given by a Markov chain. Corresponding to each possible value of the channel state the packet drop probability distribution may be different. We design an event-triggered transmission policy that ensures that the second moment of the plant state converges exponentially, at a desired rate, to an ultimate bound. Our approach relies on an online assessment of the necessity of transmission at any given time step and a transmission occurs only if necessary. We illustrate the results through simulations.}, keywords = {Control and Optimisation, Networked Control systems}, pubstate = {published}, tppubtype = {conference} } In this paper, we consider the problem of second moment stabilization of scalar linear systems under Markov packet drops. We assume that the channel state evolution is given by a Markov chain. Corresponding to each possible value of the channel state the packet drop probability distribution may be different. We design an event-triggered transmission policy that ensures that the second moment of the plant state converges exponentially, at a desired rate, to an ultimate bound. Our approach relies on an online assessment of the necessity of transmission at any given time step and a transmission occurs only if necessary. We illustrate the results through simulations. |
| 48. | Shourya Bose; Pavankumar, Tallapragada Event-Triggered Stabilization under Action-Dependent Markov Packet Drops Journal Article The Insitute of Engineering and Technology, 2019. Abstract | BibTeX | Tags: Electrical Engineering | Links: @article{@Shouryab, title = {Event-Triggered Stabilization under Action-Dependent Markov Packet Drops}, author = {Shourya Bose; Pavankumar, Tallapragada}, url = {https://cps.iisc.ac.in/wp-content/uploads/2020/10/Event-Triggered-Stabilization-under-Action-Dependent-Markov-Packet-Drops.pdf}, year = {2019}, date = {2019-12-28}, journal = {The Insitute of Engineering and Technology}, abstract = {In this paper, we consider the problem of second moment stabilization of a scalar linear plant with process noise. We assume that the sensor must communicate with the controller over an unreliable channel, whose state evolves according to a Markov chain, with the transition matrix on a timestep depending on whether there is a transmission or not on that timestep. Under such a setting, we propose an event-triggered transmission policy which meets the objective of exponential convergence of the second moment of the plant state to an ultimate bound. Furthermore, we provide upper bounds on the transmission fraction of the proposed policy. We illustrate the proposed action-dependent channel framework through an example scenario of control in the presence of an energy harvesting sensor equipped with a battery. We verify the proposed control design as well as the analytical guarantees through simulations for the example scenario.}, keywords = {Electrical Engineering}, pubstate = {published}, tppubtype = {article} } In this paper, we consider the problem of second moment stabilization of a scalar linear plant with process noise. We assume that the sensor must communicate with the controller over an unreliable channel, whose state evolves according to a Markov chain, with the transition matrix on a timestep depending on whether there is a transmission or not on that timestep. Under such a setting, we propose an event-triggered transmission policy which meets the objective of exponential convergence of the second moment of the plant state to an ultimate bound. Furthermore, we provide upper bounds on the transmission fraction of the proposed policy. We illustrate the proposed action-dependent channel framework through an example scenario of control in the presence of an energy harvesting sensor equipped with a battery. We verify the proposed control design as well as the analytical guarantees through simulations for the example scenario. |
| 49. | Eduardo Hargreavesa; Claudio Agosti; Daniel Menasché; Giovanni Neglia; Alexandre Reiffers-Masson; Eitan, Altman Fairness in Online Social Network Timelines: Measurements, Models and Mechanism Design Journal Article IFIP Perfomance 2018 - 36th International Symposium on Computer Performance, Modeling, Measurements and Evaluation, 129 , pp. 15-39, 2019. Abstract | BibTeX | Tags: measuremets | Links: @article{@Alex2019, title = {Fairness in Online Social Network Timelines: Measurements, Models and Mechanism Design}, author = {Eduardo Hargreavesa; Claudio Agosti; Daniel Menasché; Giovanni Neglia; Alexandre Reiffers-Masson; Eitan, Altman}, url = {http://10.0.54.4/wp-content/uploads/2019/11/Fairness-in-Online-Social-Network-Timelines-Measurements-Models-and-Mechanism-Design-Journal-Article.pdf}, doi = {10.1016/j.peva.2018.09.009}, year = {2019}, date = {2019-02-01}, journal = {IFIP Perfomance 2018 - 36th International Symposium on Computer Performance, Modeling, Measurements and Evaluation}, volume = {129}, pages = {15-39}, abstract = {Facebook News Feed personalization algorithm has a significant impact, on a daily basis, on the lifestyle, mood and opinion of millions of Internet users. Nonetheless, the behavior of such algorithm lacks transparency, motivating measurements, modeling and analysis in order to understand and improve its properties. In this paper, we propose a reproducible methodology encompassing measurements, an analytical model and a fairness-based News Feed design. The model leverages the versatility and analytical tractability of time-to-live (TTL) counters to capture the visibility and occupancy of publishers over a News Feed. Measurements are used to parameterize and to validate the expressive power of the proposed model. Then, we conduct a what–if analysis to assess the visibility and occupancy bias incurred by users against a baseline derived from the model. Our results indicate that a significant bias exists and it is more prominent at the top position of the News Feed. In addition, we find that the bias is non-negligible even for users that are deliberately set as neutral with respect to their political views, motivating the proposal of a novel and more transparent fairness-based News Feed design.}, keywords = {measuremets}, pubstate = {published}, tppubtype = {article} } Facebook News Feed personalization algorithm has a significant impact, on a daily basis, on the lifestyle, mood and opinion of millions of Internet users. Nonetheless, the behavior of such algorithm lacks transparency, motivating measurements, modeling and analysis in order to understand and improve its properties. In this paper, we propose a reproducible methodology encompassing measurements, an analytical model and a fairness-based News Feed design. The model leverages the versatility and analytical tractability of time-to-live (TTL) counters to capture the visibility and occupancy of publishers over a News Feed. Measurements are used to parameterize and to validate the expressive power of the proposed model. Then, we conduct a what–if analysis to assess the visibility and occupancy bias incurred by users against a baseline derived from the model. Our results indicate that a significant bias exists and it is more prominent at the top position of the News Feed. In addition, we find that the bias is non-negligible even for users that are deliberately set as neutral with respect to their political views, motivating the proposal of a novel and more transparent fairness-based News Feed design. |
| 50. | Babu, Arun; Thomas, Jithin Jose Freestyle, a randomized version of ChaCha for resisting offline brute-force and dictionary attacks Journal Article Forthcoming Journal of Information Security and Applications, 49 , Forthcoming. Abstract | BibTeX | Tags: Smart City | Links: @article{Babu2019, title = {Freestyle, a randomized version of ChaCha for resisting offline brute-force and dictionary attacks}, author = {Arun Babu and Jithin Jose Thomas}, url = {http://10.0.54.4/wp-content/uploads/2019/10/Freestyle-a-randomized-version-of-ChaCha-for-resisting-offline-brute-force-and-dictionary-attacks.pdf}, doi = {10.1016/j.jisa.2019.102396}, year = {2019}, date = {2019-12-01}, journal = {Journal of Information Security and Applications}, volume = {49}, abstract = {This paper introduces Freestyle, a randomized and variable round version of the ChaCha cipher. Freestyle uses the concept of hash based halting condition where a decryption attempt with an incorrect key is likely to take longer time to halt. This makes Freestyle resistant to key-guessing attacks i.e. brute-force and dictionary based attacks. Freestyle demonstrates a novel approach for ciphertext randomization by using random number of rounds for each block, where the exact number of rounds are unknown to the receiver in advance. Freestyle provides the possibility of generating 2^128 different ciphertexts for a given key, nonce, and message; thus resisting key and nonce reuse attacks. Due to its inherent random behavior, Freestyle makes cryptanalysis through known-plaintext, chosen-plaintext, and chosen-ciphertext attacks difficult in practice. On the other hand, Freestyle has costlier cipher initialization process, typically generates 3.125% larger ciphertext, and was found to be 1.6 to 3.2 times slower than ChaCha20. Freestyle is suitable for applications that favor ciphertext randomization and resistance to key-guessing and key reuse attacks over performance and ciphertext size. Freestyle is ideal for applications where ciphertext can be assumed to be in full control of an adversary, and an offline key-guessing attack can be carried out. }, keywords = {Smart City}, pubstate = {forthcoming}, tppubtype = {article} } This paper introduces Freestyle, a randomized and variable round version of the ChaCha cipher. Freestyle uses the concept of hash based halting condition where a decryption attempt with an incorrect key is likely to take longer time to halt. This makes Freestyle resistant to key-guessing attacks i.e. brute-force and dictionary based attacks. Freestyle demonstrates a novel approach for ciphertext randomization by using random number of rounds for each block, where the exact number of rounds are unknown to the receiver in advance. Freestyle provides the possibility of generating 2^128 different ciphertexts for a given key, nonce, and message; thus resisting key and nonce reuse attacks. Due to its inherent random behavior, Freestyle makes cryptanalysis through known-plaintext, chosen-plaintext, and chosen-ciphertext attacks difficult in practice. On the other hand, Freestyle has costlier cipher initialization process, typically generates 3.125% larger ciphertext, and was found to be 1.6 to 3.2 times slower than ChaCha20. Freestyle is suitable for applications that favor ciphertext randomization and resistance to key-guessing and key reuse attacks over performance and ciphertext size. Freestyle is ideal for applications where ciphertext can be assumed to be in full control of an adversary, and an offline key-guessing attack can be carried out. |
