Optimal internal model control with specified decay rate for AUV under irregular wave forces

This paper presents an optimal internal model control (OIMC) algorithm for heading control problem of Autonomous Underwater Vehicle (AUV) affected by irregular wave forces. Firstly, the AUV system model is proposed, and the exosystem of irregular wave forces is obtained based on the Morison equation. Secondly, the disturbances compensator is designed by using internal model. And a new augmented system is constructed, by taking the system and the disturbances compensator in series. Then the optimal control problem of AUV nonlinear system is transformed into the optimal regulator design problem of an augmented system. The OIMC law is designed according to the theory of the quadratic optimal control and stability degree constraint. Finally, the controller is applied to the heading control of AUV with irregular wave forces disturbances, and the results demonstrate the effectiveness and robustness of the controller.