A Finite-Time Disturbance Observer Based Full-Order Terminal Sliding-Mode Controller for Manned Submersible with Disturbances

Abstract

A novel full-order terminal sliding-mode controller (FOTSMC) based on the finite-time disturbance observer (FTDO) is proposed for the “JIAOLONG” manned submersible with lumped disturbances. First, a finite-time disturbance observer (FTDO) is developed to estimate the lumped disturbances including the external disturbances and model uncertainties. Second, a full-order terminal sliding-mode surface is designed for the manned submersible, whose sliding-mode motion behaves as full-order dynamics rather than reduced-order dynamics in conventional sliding-mode control systems. Then, a continuous sliding-mode control law is developed to avoid chattering phenomenon, as well as to drive the system outputs to the desired reference trajectory in finite time. Furthermore, the closed-loop system stability analysis is given by Lyapunov theory. Finally, the simulation results demonstrate the satisfactory tracking performance and excellent disturbance rejection capability of the proposed finite-time disturbance observer based full-order terminal sliding-mode control (FTDO-FOTSMC) method.

Adaptive Tracking Control for Spacecraft Formation Flying System via Modified Fast Integral Terminal Sliding Mode Surface

“…Theorem 1. Consider the spacecraft formation flying system given in ( 19)- (20) with the proposed fast integral terminal sliding mode surface (30), the control law is designed as…”

“…Theorem 2. Consider the external disturbances in spacecraft formation flying system ( 19)- (20), with the following reduced-order disturbance observer,…”

“…First, we should prove the disturbance can converge to zero in finite time. According to the spacecraft formation flying system shown in ( 19)- (20), the disturbance vector d can be rewritten as follows,…”

“…In this subsection, an adaptive fast integral terminal sliding mode control law is proposed for the spacecraft formation flying system. An adaptive updating law is derived to compensate for the uncertainties in the system ( 19)- (20). The block diagram of the fast integral terminal sliding mode control law with adaptive updating law is given in Figure 4.…”

“…The spacecraft formation flying consists of two key factors: external disturbances [20] and parametric uncertainty [21], which both have major impacts on the control accuracy and performance of the system. In order to improve the tracking accuracy while maintaining the robustness against external disturbances, several control methods have been applied to suppress and estimate the disturbances [22], [23].…”