During sea missions, underwater vehicles are exposed to changes in the parameters of the system and subject to persistent external disturbances due to the ocean current influence. These issues make the design of a robust controller a quite challenging task. This paper focuses on the design of a adaptive high order sliding mode control for trajectory tracking on an underwater vehicle. The main feature of the developed control law is that it preserves the advantages of robust control, it does not need the knowledge of the upper bound of the disturbance and easy tuning in real applications. Using Lyapunov concept, asymptotic stability of the closed-loop tracking system is ensured. The effectiveness and robustness of the proposed controller for trajectory tracking in depth and yaw dynamics are demonstrated through real-time experiments.

International audienceThis paper deals with two nonlinear controllers based on saturation functions with varying parameters, for set-point regulation and trajectory tracking on an Underwater Vehicle. The proposed controllers combine the advantages of robust control and easy tuning in real applications. The stability of the closed-loop system with the proposed nonlinear controllers is proven by Lyapunov arguments. Experimental results for the trajectory tracking control in 2 degrees of freedom, these are the depth and yaw motion of an underwater vehicle, show the performance of the proposed control strategy