For a nonlinear course keeping system of ships, asymmetric information theory and robust control algorithm were applied to simplify nonlinear backstepping algorithm, through the algorithm, the controller was converted into nonlinear items plus a normal linear control item, and a simplified nonlinear robust control algorithm was presented, which connected the backstepping algorithm with closed-loop gain shaping algorithm. Simulation result shows that the ship can keep the set course without overshoot and steady state error, the regulating time is 600 s, these control indexes accord with the actual condition of ship navigation, and the course keeping performance is improved. When wind and wave disturbances are introduced into the system, the control effects are satisfied, the output course does not have steady state error, the controller has good robustness. The control effect does not vary obviously whether the nonlinear items are cancelled or not, the control performance is guaranteed.
