Finite-time sliding mode control for a 3-DOF fully actuated autonomous surface vehicle

This paper deals with the finite-time trajectory tracking problem for a typical 3-DOF (degree of freedom) autonomous surface vehicle (ASV) subjected to parametric uncertainties and environmental disturbances. Based on the nonsingular terminal sliding mode control (NTSMC) method, several separate classes of robust control inputs are designed to exactly steer all position states of the 3-DOF AVS to the desired paths during alterable finite times. By exploiting the Lyapunov stability theorem and using mathematical analysis, it is proven that all classes of designed robust control inputs are able to fulfill the mentioned finite-time tracking aim. Moreover, three applicable formulas (represented as several nonlinear inequalities) are extracted to determine the required total finite times for the suggested control schemes. Lastly, all designed control methods are numerically tested onto a benchmark 3-DOF AVS called CyberShip II. Provided computer-based numerical simulations (using MATLAB software) depicted the acceptable performance of the proposed control techniques.