Modeling, parameter identification, guidance and control of an unmanned surface vehicle with experimental results

This work proposes an autopilot scheme for self-steering an Unmanned Surface Vehicle (USV) in terms of heading and speed control, route following and waypoints tracking. The majority of regulators developed in the literature only provide heading control, which is a considerable weakness since the drift effects due to wind and marine currents cause the USV to move away from the planned path. This work deals with this problem and firstly proposes a mathematical model with three degrees of freedom for simulating the USV behavior. Second, USV parameter are calculated experimentally, and then an autopilot system is designed letting the USV to rapidly and smoothly reach a desired path and remain precisely on it. The developed autopilot, which is based on sliding mode control, consists of two levels of regulation, low-level controller for speed and heading control and a high-level controller for generating the desired speed and heading according to two different navigation modes: waypoints tracking and/or path following. Experimental results are carried out to verify the effectiveness of the proposed autopilot in term of heading control for waypoints tracking.