Xu Jin

(Advisor: Prof. Haddad)

will defend a doctoral thesis entitled,

Cyber-Physical System Security, Optimal Control, and

Consensus Protocols for Nonlinear Stochastic Systems

On

Tuesday, July 2 at 2pm.
Montgomery Knight Building 317

Abstract
 

Recent technological advances in communications and computation have spurred a broad interest in control law architectures involving the monitoring, coordination, integration, and operation of sensing, computing, and communication components that tightly interact with the physical processes that they control. These systems are known as cyber-physical systems and due to their use of open computation and communication platform architectures, controlled cyber-physical systems are vulnerable to adversarial attacks.  In this presentation, we first develop a distributed robust adaptive control architecture that can foil malicious sensor and actuator attacks in the face of exogenous stochastic disturbances and follower agent model uncertainties. Specifically, for a class of linear multiagent uncertain systems with an undirected communication graph topology we develop a neighborhood synchronization error for the distributed robust adaptive control protocol design of each follower to account for actuator and sensor attacks on the leader state as well as all of the follower agents in the network. The proposed robust adaptive controller guarantees uniform ultimate boundedness in probability of the state tracking error for each follower agent in a mean-square sense.

    Next, a constructive finite time stabilizing feedback control law is derived next for stochastic dynamical systems driven by Wiener processes based on the existence of a stochastic control Lyapunov function. Moreover, using stochastic control Lyapunov functions, we construct a universal inverse optimal feedback control law for nonlinear stochastic dynamical systems that possesses guaranteed gain and sector margins.

    Finally, we focus on semistability and finite time semistability analysis and synthesis of stochastic dynamical systems having a continuum of equilibria. We extend the theories of semistability and finite-time semistability for deterministic dynamical systems to develop a rigorous framework for stochastic semistability and stochastic finite-time semistability. Specifically, Lyapunov and converse Lyapunov theorems for stochastic semistability are developed for dynamical systems driven by Markov diffusion processes. These results are then used to develop a general framework for designing semistable consensus protocols for dynamical networks in the face of stochastic communication uncertainty for achieving multiagent coordination tasks in finite time.

Committee

• Prof. Wassim M. Haddad – School of Aerospace Engineering (advisor)
• Prof. John-Paul B Clarke – School of Aerospace Engineering
• Prof. Kyriakos Vamvoudakis – School of Aerospace Engineering
• Prof. Yongxin Chen – School of Aerospace Engineering
• Prof. Fumin Zhang – School of Electrical and Computer Engineering