Konstantinos Gatsis & Miroslav Pajic,
University of Pennsylvania
Opportunistic Scheduling of Control Tasks Over Shared Wireless Channels
Abstract: We consider a wireless networked control system with multiple loops closing over a shared wireless medium. To avoid interferences a centralized scheduler decides which control task accesses the channel at each time step, opportunistically based on the random wireless channel conditions that systems experience. We formulate the problem of designing channel-aware scheduling and transmit power allocation mechanisms that guarantee Lyapunov-like control performance for all tasks in expectation over the channel conditions, while they also minimize the total power expenditures. Exploiting the zero duality gap, optimal variables are obtained by solving at the dual domain either offline, or online based on the observed random channel sequence. Simulations illustrate the power savings of the proposed scheme.
Robustness of Attack-resilient State Estimators
Abstract: The interaction between information technology and physical world makes Cyber-Physical Systems (CPS) vulnerable to malicious attacks beyond the standard cyber attacks. This has motivated the need for attack-resilient state estimation. Yet, the existing state-estimators are based on the non-realistic assumption that the exact system model is known. Consequently, in this work we present a method for state estimation in presence of attacks, for systems with noise and modeling errors. When the the estimated states are used by a state-based feedback controller, we show that the attacker cannot destabilize the system by exploiting the difference between the model used for the state estimation and the real physical dynamics of the system. Furthermore, we describe how implementation issues such as jitter, latency and synchronization errors can be mapped into parameters of the state estimation procedure that describe modeling errors, and provide a bound on the state-estimation error caused by modeling errors. This enables mapping control performance requirements into real-time (i.e., timing related) specifications imposed on the underlying platform. Finally, we illustrate and experimentally evaluate this approach on an unmanned ground vehicle case-study.
Biography: Konstantinos Gatsis received the Diploma degree in electrical and computer engineering from the University of Patras, Patras, Greece in 2010. Currently, he is working toward the Ph.D. degree in the Department of Electrical and Systems Engineering, University of Pennsylvania, Philadelphia. His research interests include cyber-physical systems, networked control systems, as well as resource optimization problems arising in them. Mr. Gatsis received the Student Best Paper Award at the 2013 American Control Conference.
Biography: Miroslav Pajic is a Postdoctoral Researcher in the Department of Electrical & Systems Engineering and PRECISE Center (Penn Research in Embedded Computing and Integrated System) at the University of Pennsylvania. He received his Ph.D. and M.S. degrees in Electrical Engineering from the University of Pennsylvania in 2012 and 2010, and the M.S. and Dipl. Ing. degrees from the University of Belgrade, Serbia, in 2007 and 2003, respectively. His research interests focus on the design and analysis of cyber-physical systems and in particular real-time and embedded systems, distributed/networked control system, and high-confidence medical device systems. Dr. Pajic received various awards including the ACM SIGBED Frank Anger Memorial Award, the Joseph and Rosaline Wolf Award for Best Dissertation in Electrical and Systems Engineering from Penn Engineering, the Best Student Paper Award at the 2012 IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS), and Honeywell User Group Wireless Innovation Award.