Adaptive Control for Nonlinear Systems With Input and Output Quantization Under DoS Attacks

Abstract

Under intermittent cyber attacks, an adaptive control strategy has been proposed for a class of nonlinear systems with input and output quantization. Unlike existing studies on denial-of-service attacks (DoS), the system dynamics in this paper are unknown. Since the system dynamics are unknown and both input and output signals are affected by DoS attacks, system variables are not directly observable. To address this issue, a fuzzy observer with switchable gains is proposed. In contrast to conventional DoS attacks research, both input and output signals in this work are quantized prior to transmission, rendering traditional backstepping control methods inapplicable. To solve this problem, the following steps are proposed: Firstly, an auxiliary intermediate controller is designed using the unquantized states. Secondly, by replacing the unquantized states with quantized states in the auxiliary intermediate controller, the intermediate controller and the actual controller are obtained. Thirdly, to compensate for the impact of quantization errors, Lemma 4 is introduced, and the control strategies are first proposed to guarantee the stability of the nonlinear system in the presence of DoS attacks. Furthermore, simulation results are presented to demonstrate the efficiency of the proposed control method.