An experimental comparison of two USV trajectory tracking control laws

This paper describes development and testing of two trajectory tracking control algorithms for an unmanned surface vehicle (USV): a cascade of proportional derivative controllers and a nonlinear controller obtained through backstepping. The control laws are designed to force the vehicle trajectory to converge to a reference trajectory generated using an experimentally identified dynamic model of the USV. Experimental results indicate that the backstepping controller is much more effective at tracking trajectories that involve large variations in speed and course angle. The backstepping control law is extended to accommodate a constant ambient flow. Simulations of the reformulated backstepping controller in a flow field further illustrate its effectiveness.