Biblio

Filters: Author is Shankar Sastry  [Clear All Filters]
2021-12-21
Victoria Tuck, Yash Vardhan Pant, Sanjit A. Seshia, Shankar Sastry.  2021.  Decentralized path planning for multi-robot systems with Line-of-sight constrained communication. 2021 IEEE Conference on Control Technology and Applications (CCTA).

Decentralized planning for multi-agent systems,such as fleets of robots in a search-and-rescue operation, is oftenconstrained by limitations on how agents can communicate witheach other. One such limitation is the case when agents cancommunicate with each other only when they are in line-of-sight (LOS). Developing decentralized planning methods thatguarantee safety is difficult in this case, as agents that areoccluded from each other might not be able to communicateuntil it’s too late to avoid a safety violation. In this paper, wedevelop a decentralized planning method that explicitly avoidssituations where lack of visibility of other agents would leadto an unsafe situation. Building on top of an existing Rapidly-exploring Random Tree (RRT)-based approach, our methodguarantees safety at each iteration. Simulation studies showthe effectiveness of our method and compare the degradationin performance with respect to a clairvoyant decentralizedplanning algorithm where agents can communicate despite notbeing in LOS of each other.

Amay Saxena, Chih-Yuan Chiu, Joseph Menke, Ritika Shrivastava, Shankar Sastry.  2021.  Simultaneous Localization and Mapping: Through the Lens of Nonlinear Optimization.

Simultaneous Localization and Mapping (SLAM) algorithms perform visual-inertial estimation via filtering or batch optimization methods. Empirical evidence suggests that filtering algorithms are computationally faster, while optimization methods are more accurate. This work presents an optimization-based framework that unifies these approaches, and allows users to flexibly implement different design choices, e.g., the number and types of variables maintained in the algorithm at each time. We prove that filtering methods correspond to specific design choices in our generalized framework. We then reformulate the Multi-State Constrained Kalman Filter (MSCKF), implement the reformulation on challenging image sequence datasets in simulation, and contrast its performance with that of sliding window based filters. Using these results, we explain the relative performance characteristics of these two classes of algorithms in the context of our algorithm. Finally, we illustrate that under different design choices, the empirical performance of our algorithm interpolates between those of state-of-the-art approaches.

2019-09-27
Janos Sztipanovits, Xenofon Koutsoukos, Gabor Karsai, Shankar Sastry, Claire Tomlin, Werner Damm, Martin Fränzle, Jochem Rieger, Alexander Pretschner, Frank Köster.  2019.  Science of design for societal-scale cyber-physical systems: challenges and opportunities. Cyber-Physical Systems. 5:145-172.

Emerging industrial platforms such as the Internet of Things (IoT), Industrial Internet (II) in the US and Industrie 4.0 in Europe have tremendously accelerated the development of new generations of Cyber-Physical Systems (CPS) that integrate humans and human organizations (H-CPS) with physical and computation processes and extend to societal-scale systems such as traffic networks, electric grids, or networks of autonomous systems where control is dynamically shifted between humans and machines. Although such societal-scale CPS can potentially affect many aspect of our lives, significant societal strains have emerged about the new technology trends and their impact on how we live. Emerging tensions extend to regulations, certification, insurance, and other societal constructs that are necessary for the widespread adoption of new technologies. If these systems evolve independently in different parts of the world, they will ‘hard-wire’ the social context in which they are created, making interoperation hard or impossible, decreasing reusability, and narrowing markets for products and services. While impacts of new technology trends on social policies have received attention, the other side of the coin – to make systems adaptable to social policies – is nearly absent from engineering and computer science design practice. This paper focuses on technologies that can be adapted to varying public policies and presents (1) hard problems and technical challenges and (2) some recent research approaches and opportunities. The central goal of this paper is to discuss the challenges and opportunities for constructing H-CPS that can be parameterized by social context. The focus in on three major application domains: connected vehicles, transactive energy systems, and unmanned aerial vehicles.Abbreviations: CPS: Cyber-physical systems; H-CPS: Human-cyber-physical systems; CV: Connected vehicle; II: Industrial Internet; IoT: Internet of Things

2019-08-21
Janos Sztipanovits, Xenofon Koutsoukos, Gabor Karsai, Shankar Sastry, Claire Tomlin, Werner Damm, Martin Frönzle, Jochem Rieger, Alexander Pretschner, Frank Köster.  2019.  Science of design for societal-scale cyber-physical systems: challenges and opportunities. Cyber-Physical Systems. 5:145-172.

Emerging industrial platforms such as the Internet of Things (IoT), Industrial Internet (II) in the US and Industrie 4.0 in Europe have tremendously accelerated the development of new generations of Cyber-Physical Systems (CPS) that integrate humans and human organizations (H-CPS) with physical and computation processes and extend to societal-scale systems such as traffic networks, electric grids, or networks of autonomous systems where control is dynamically shifted between humans and machines. Although such societal-scale CPS can potentially affect many aspect of our lives, significant societal strains have emerged about the new technology trends and their impact on how we live. Emerging tensions extend to regulations, certification, insurance, and other societal constructs that are necessary for the widespread adoption of new technologies. If these systems evolve independently in different parts of the world, they will ‘hard-wire’ the social context in which they are created, making interoperation hard or impossible, decreasing reusability, and narrowing markets for products and services. While impacts of new technology trends on social policies have received attention, the other side of the coin – to make systems adaptable to social policies – is nearly absent from engineering and computer science design practice. This paper focuses on technologies that can be adapted to varying public policies and presents (1) hard problems and technical challenges and (2) some recent research approaches and opportunities. The central goal of this paper is to discuss the challenges and opportunities for constructing H-CPS that can be parameterized by social context. The focus in on three major application domains: connected vehicles, transactive energy systems, and unmanned aerial vehicles.Abbreviations: CPS: Cyber-physical systems; H-CPS: Human-cyber-physical systems; CV: Connected vehicle; II: Industrial Internet; IoT: Internet of Things

Karsten Lemmer, Werner Damm, Janos Stzipanovits, Shankar Sastry, Claire Tomlin, Frank Köster, Meike Jipp.  2019.  Societal and Technological Research Challenges for Highly Automated Road Transportation Systems in Germany and the US: Diversities and Synergy Potentials. Workshop on Societal and Technological Research Challenges for Highly Automated Road Transportation Systems in Germany and the US: Diversities and Synergy Potentials.
2018-05-27
Dorsa Sadigh, Anca Dragan, Shankar Sastry, Sanjit A. Seshia.  2017.  Active Preference-Based Learning of Reward Functions. Proceedings of the Robotics: Science and Systems Conference (RSS).
2017-10-27
Aron Laszka, Waseem Abbas, Shankar Sastry, Yevgeniy Vorobeychik, Xenofon Koutsoukos.  2016.  Optimal Thresholds for Intrusion Detection Systems. 3rd Annual Symposium and Bootcamp on the Science of Security (HotSoS).

In recent years, we have seen a number of successful attacks against high-profile targets, some of which have even caused severe physical damage. These examples have shown us that resourceful and determined attackers can penetrate virtually any system, even those that are secured by the "air-gap." Consequently, in order to minimize the impact of stealthy attacks, defenders have to focus not only on strengthening the first lines of defense but also on deploying effective intrusion-detection systems. Intrusion-detection systems can play a key role in protecting sensitive computer systems since they give defenders a chance to detect and mitigate attacks before they could cause substantial losses. However, an over-sensitive intrusion-detection system, which produces a large number of false alarms, imposes prohibitively high operational costs on a defender since alarms need to be manually investigated. Thus, defenders have to strike the right balance between maximizing security and minimizing costs. Optimizing the sensitivity of intrusion detection systems is especially challenging in the case when multiple interdependent computer systems have to be defended against a strategic attacker, who can target computer systems in order to maximize losses and minimize the probability of detection. We model this scenario as an attacker-defender security game and study the problem of finding optimal intrusion detection thresholds.

2018-05-27
Dorsa Sadigh, Shankar Sastry, Sanjit A. Seshia, Anca D. Dragan.  2016.  Information Gathering Actions Over Human Internal State. Proceedings of the IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS). :66–73.
2017-10-27
Saurabh Amin, Galina A. Schwartz, Alvaro Cardenas, Shankar Sastry.  2015.  Game-Theoretic Models of Electricity Theft Detection in Smart Utility Networks. IEEE CONTROL SYSTEMS MAGAZINE.
The article by Amin, Schwartz, Cárdenas, and Sastry investigates energy theft in smart utility networks using techniques from game theory and detection theory. The game-theoretic model considers pricing and investment decisions by a distribution utility when it serves a population of strategic customers, and a fraction of customers are fraudulent. Each fraudulent customer chooses to steal electricity after accounting for the probability of fraud detection and the amount of fine that they pay if detected. The probabilistic rate of successful detection depends on the distributor's implementation of a diagnostic scheme and increases with level of investment made by the distributor monitoring fraud. The distributor (leader) chooses the level of investment, the price per unit quantity of billed electricity, and the fine schedule. The customers (followers) make their choices after they learn the distributor's decision. For specific assumptions on customer utilities and a distributor's profit function, this leader-follower game is used to compute equilibrium customer and distributor choices. For two environments, namely an unregulated monopoly and the case of perfect competition, the results provide an estimate of the extent of stealing for different levels of investment (high versus low). These results point toward the need for creating regulatory measures to incentivize investments in security and fraud monitoring.