Non-Linear Robust Control Designs for a Remotely Operated Underwater Vehicle Depth Control System

Abstract

This paper describes the heave and pitch control of a non-linear longitudinal model of a remotely operated vehicle (ROV) using three robust non-linear control techniques. The techniques are based on input-output (I/O) linearization, comprising basic I/O linearization control, I/O linearization with sliding mode control and I/O linearization with adaptive fuzzy systems. Robustness of the designs is investigated by examining the closed-loop zero dynamics, which are shown to be bounded. The robustness of each control scheme is also investigated by varying the ROV hydrodynamic coefficients by 50 per cent. Simulation results are presented to compare the control schemes.