Tracking for nonlinear underactuated surface vessels with generalized forces

This paper describes how to use backstepping to develop control laws to perform trajectory tracking for a nonlinear, underactuated surface vessel. The research extends earlier backstepping designs for underactuated vessels by explaining how to select outputs when generalized forces act on the vessel. The resulting control law can correct orientation errors to track linear trajectories and can track arcs of circles with a fixed offset. The paper provides detailed derivations along with simulation results to illustrate the approach.