Disturbance Rejection Control for Underwater Free-Floating Manipulation

Abstract

This article presents a disturbance observer-based control (DOBC) framework for an autonomous underwater biomimetic vehicle-manipulator system (UBVMS) to implement underwater manipulation under unknown external disturbances. First, a fast arctangent nonsingularity terminal sliding mode controller (FANTSMC) with the inverse trigonometric function approach law is proposed to achieve the control of the UBVMS. Then, an improved high-order observer is proposed to track unknown disturbances including external disturbances and the manipulator compensation errors in a finite time. Finally, the DOBC framework, which consists of the FANTSMC and the disturbance observer, is applied to the underwater manipulation. Comparative simulations and practical underwater manipulation are conducted to validate the performance of our proposed method in disturbance tracking and underwater manipulation realization.