Adaptive Control for High-Order Strict-Feedback System Based on Fully Actuated System Approach

This paper studies the tracking control problem of a class of uncertain high-order strict-feedback nonlinear systems with full-state constraints and external disturbances. Firstly, the constrained subsystem is transformed into a high-order fully actuated form of an unconstrained subsystem through coordinate transformation. Secondly, the fully actuated approach is utilized to directly propose the virtual controller acting on the subsystem and the backstepping is employed to derive the final control law. To solve the “differential explosion” problem in the backstepping process, a command filter is introduced. On this basis, the adaptive control is applied to suppress the influence of uncertainties and external disturbances. The stability analysis shows that all signals in the closed-loop system are bounded, and the tracking error can converge to a predefined and adjustable compact set. Taking the single-link flexible joint manipulator system as an example for simulation verification, the results show that this method has more advantages in the convergence speed of the tracking error.