A simple and direct nonlinear robust control algorithm

For a given affine nonlinear system which can be linearized by full state feedback linearization, a simple and direct nonlinear robust control algorithm was presented. The design method of nonlinear robust controller was given firstly based on state feedback linearization and closed-loop gain shaping algorithm, then the design procedure of the simple and direct nonlinear robust control algorithm was summarized. According to above procedure, a nonlinear robust controller of the rudder/fin joint nonlinear system was designed. Under Beaufort No. 6 and 8 sea states, the nonlinear rudder/fin joint control system with rudder/fin servo systems was simulated using Simulink. Simulation results show that this control strategy has nice robust performance on course-keeping and roll stabilization. The research in the paper has the advantages of simple design procedure and obvious physical sense.