Observer design for labeled finite automata with inputs under stealthy actuators attacks

This paper addresses the problem of cyber-attacks in discrete-event systems framework. Labeled finite state automata with inputs derived from a particular class of Petri net, called Output Synchronized Petri nets, are used to model a given cyber-physical system along with the information that circulate between controllers and plant. Stealthy cyber-attacks that may alter the control symbols, i.e., the orders sent by the controllers to the actuators, are considered. The objective is to construct an observer that uses both input and output information to provide a state estimation of the system under such stealthy actuators attacks. This observer provides a refined state estimation related to both normal and attack conditions.