Time-Varying Nonsingular Terminal Sliding Mode control of Autonomous Surface Vehicle with predefined convergence time

Abstract

This paper addresses the problem of trajectory tracking control of an Autonomous Surface Vehicle (ASV) with the presence of uncertainties and disturbances. First, a Time-Varying Nonsingular Terminal Sliding Mode (TV-NTSM) manifold is designed by incorporating a piecewise-defined function of time into a nonsingular terminal sliding mode (NTSM) manifold. As a result, the reaching phase that exists in traditional sliding mode is totally suppressed as well as the avoidance of the singularity problem. Then, a TV-NTSM controller is proposed to guarantee the convergence of the tracking errors to the origin in finite-time and to ensure the global robustness of the system with respect to large uncertainties and unknown environmental disturbances. To meet the mission requirement, an adequate method is given for the parameters system selection to guarantees the convergence of the tracking errors to the origin in prespecified time. Furthermore, an adaptive tuning law is introduced to estimate the unknown upper bounds of the lumped uncertainty, which is convenient for practical implementation. The stability of the closed-loop system is verified by Lyapunov theory and simulation results are carried out to prove the effectiveness of the proposed control algorithm.