Adaptive Dynamic Surface Control for High-Order Strict-Feedback Systems With Input Saturation: A Fully Actuated System Approach

Abstract

We introduce an adaptive dynamic surface control (ADSC) method tailored for high-order strict-feedback systems (SFSs) with input saturation, utilizing the fully actuated system (FAS) approach. We simplify the steps in designing the controller by combining the FAS approach with ADSC method to directly control each high-order subsystem as a complete entity, without the need to transform it into first-order systems. Smooth functions and Nussbaum functions are applied to solve the problem of input saturation. We use a sequence of low-pass filters to calculate the higher-order derivatives of the virtual control law. Lyapunov stability theory is used to demonstrate that all signals within the closed-loop system become uniformly bounded, with the tracking error ultimately converging to a small vicinity around zero. We validated the efficiency of the proposed method of control through simulations on a flexible joint manipulator system. In contrast to the traditional first-order system method, which requires four virtual control laws, the proposed method in this paper necessitates only two, resulting in a smaller initial value of the control input.