Robust Trajectory Tracking Control for Unmanned Surface Vehicles with Input Saturation

The problem of trajectory tracking for Unmanned Surface Vehicles (USVs) is investigated subject to external disturbances, model uncertainties, input saturation. As a typical USV is under-actuated, similar to the differentially driven mobile robots, we define the "hand" position of the USV, then consider the trajectory tracking problem of the "hand" position of USV. Based on signal compensation theory, a controller is proposed which incorporates a nominal controller and a robust compensator, the latter of which is introduced to restrain the effects of model uncertainties and external disturbances. Meanwhile, the problem of stability analysis of the saturated closed-loop system can be seen as a Lure problem. Under the proposed control law, the regional stability of the saturated closed-loop system can be achieved and the system has good robustness. Numerical simulations illustrate the effectiveness of the proposed trajectory tracking control law.