Combined speed and yaw control of underactuated unmanned surface vehicles

This paper studies the speed and yaw control problem for an underactuated unmanned surface vehicle (USV) with only two propellers. Firstly, it transforms the dynamical system of speed and yaw into a cascade nonlinear system, and the resulting cascade system can be reduced to the stabilization control problem of a surge speed and yaw subsystem. Secondly, the surge speed and yaw controller are proposed respectively via Lyapunov´s direct method and backstepping approach. Then, we demonstrate that the original system state is globally asymptotically stabilized to the desired configuration with the proposed feedback control law. Furthermore, the effectiveness of the proposed method is illustrated and validated by simulation results on a model ship.