Universal Zero Dynamics Attacks Using Only Input-Output Data

The main goal is to demonstrate that a zero dynamics type of attack on a nonlinear plant can be designed and executed using only input-output data. Specifically, it will be shown that a system identification scheme based solely on Chen-Fliess series can be used to synthesize an input-output model with sufficient fidelity so as to design a suitable attack signal. Central to the proposed scheme is the notion of universal zero dynamics. This is a generalization of zero dynamics for finite dimensional systems based not on a state space model, but rather on a Chen-Fliess series representation of the input-output system. In addition, a large part of the attack generation can be done offline, so this provides an open-loop approach. The ultimate goal of this line of research is to evaluate the degree of theoretical vulnerability of cyber-physical systems to such threats so that realistic defensive measures can be investigated and implemented.