Robust non-singular fast terminal sliding mode task-space position tracking control of an underwater vehicle-manipulator system

Abstract

is paper addresses a task-space trajectory control of an underwater vehicle-manipulator system (UVMS) employed for interactive underwater tasks. .e robust task-space tracking control is achieved by designing a non-singular fast terminal sliding mode controller (NFTSMC) with disturbance estimator and demonstrated on a planar underwater vehicle with serial two link manipulator arm a.ached to it. .e proposed NFTSMC integrates a non-singular fast terminal sliding mode controller (NFTSMC) with a non-linear disturbance observer. This combination not only assures €nite and faster convergence of the systems states to the equilibrium from anywhere in the phase-plane but also overcomes the problem of singularity associated with conventional terminal sliding mode controller (TSMC). In addition to this, because of the disturbance observer augmented in the proposed control law, the overall stability of the closed-loop system is enhanced to a great extent. .e feasibility of the proposed NFTSMC is con€rmed by performing extensive numerical simulation on the UVMS for tracking a given pre-de€ned task space trajectory under the in.uence of parameter uncertainties, ocean current and measurement sensor noises.