Robust corrective control against a class of actuator attacks in input/state asynchronous sequential machines

A robust corrective control scheme is proposed for input/state asynchronous sequential machines (ASMs) vulnerable to an attacker that is able to switch actuator commands. We first present mathematical descriptions of the outcome of actuator attacks in the dynamics of ASMs, and the diagnosis procedure of each attack using the state bursts. We then address the existence condition and design algorithm for a corrective controller that overcomes any actuator attack in an asynchronous mechanism. Potential reachability of the controlled ASM is fully utilized to surmount temporary corruption of actuator commands. An illustrative example is provided to show the proposed concept and methodology.