Trajectory tracking control for underactuated ships

The paper studies the stability problem of trajectory tracking control for underactuated ships with only two propellers. Using the separation principle, a control law is derived according to the surge force and the yaw momentand and a sufficient condition is obtained to ensure the global asymptotic stability of an underactuated ship. To avoid the model differentiation, the control law is easy to be implemented by linear control technique and usually has semiglobal tracking performance of underactuated ship. Finally, the stability analysis and numerical simulations are performed to confirm the effectiveness of the proposed scheme.