An active disturbance rejection control for underactuated AUV

Aiming at the problems of uncertain parameters and sensitive external interference of the underactuated autonomous underwater vehicle(AUV), an active disturbance rejection controller (ADRC) is proposed. On the basis of arranging the transition process for the desired attitude, an extended state observer is designed to compensate the total perturbations real-time, which can overcome the external disturbances such as strong coupling, model uncertainty and water flow variation. In addition, the nonlinear state error feedback is designed to effectively suppress the tracking error. The stability control, disturbance immunity and robustness of the ADRC system are tested on the simulation platform, and the quantitative analysis is carried out with cascade PID control system. The results from the simulation prove that the designed active disturbance rejection controller can estimate and compensate the internal and external interference of the system well. Also it has strong robustness to the uncertainty of the parameters of the AUV. The performance index is obviously better than cascade PID.