Dual Closed-Loop Sliding Mode Predictive Tracking Control of Unmanned Underwater Vehicles with Unknown Disturbances

This paper provides a sliding mode predictive control technique for the trajectory tracking control issue when unmanned underwater vehicles (UUVs) are on missions with unknown disturbances. In order to convert the trajectory tracking problem into an optimization problem for the receding horizon optimization governor and produce the velocity reference value for the dynamics system, a receding horizon optimization governor based on a nonlinear model prediction algorithm is first designed,which achieves the constraints on the position and velocity of the UUV, so that the UUV can safely finish the trajectory tracking task. Then, based on the inner-loop dynamical system, a fast integral terminal sliding mode (ITSM) controller is designed, which can use the upper bound information of the disturbance norm to realize the finite time control of the inner loop dynamical system in the environment with the current disturbance, and then make the actual speed of the UUV in tracking the desired speed of tracking generated by the outer loop quickly. The method also eliminates the reaching phase of the sliding mode control (SMC) due to the sliding mode surface being used in integral form, which enhances the robustness of the system while increasing the speed of error convergence. Finally, the method is analyzed and validated by simulation experiments.