Control of MIMO nonlinear discrete-time systems with input saturation via data-driven model-free adaptive fast terminal sliding mode controller

Abstract

The aim of the present paper is to design a robust and model-free adaptive controller using a nonlinear fast terminal sliding manifold for discrete-time MIMO nonlinear systems while the system inputs are constrained by magnitude and rate constraints. Firstly, by utilizing the dynamic-linearization technique, nonlinear dynamics of the system are expressed by dynamically linear equivalent data model, and an adaptive rule and multi observers are presented to predict the pseudo partitioned Jacobian matrix and the outputs of the plant, respectively. Secondly, in order to attenuate the effect of the input constraints in tracking performance of the controller, the modified tracking error vector is designed by taking the anti-windup compensator into consideration. Finally, data-driven nonlinear fast terminal sliding mode constrained control is investigated in order to increase the robustness of the closed-loop plant and enhance the tracking performance. The Lyapunov theorem is utilized to study the stability of the overall closed loop plant. Meanwhile, the simulation results are presented to accredit the robustness of the proposed method against input constraints and external perturbations.