Design of Robust P-PD Controller for an AUV Using Quantitative Feedback Theory (QFT) in the Diving Plane

Document Type : Research Article

Authors

1 Department of Mechanical Engineering, Yazd University, Yazd, Iran

2 Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran

Abstract

In this paper, a robust P-PD controller is designed for an AUV (Autonomous underwater vehicle) using QFT (Quantitative Feedback Theory) in the presence of plant uncertainty and disturbances in diving plane motion. The PD (proportional-derivative) controller controls the angle of the vehicle pitch and an outer P loop controller will control the vehicle depth. Since using classical methods to adjust PD for the inner loop and P for the outer loop, despite the plant uncertainty and the presence of disturbances, is complex and time-consuming, therefore, the QFT technique, as a robust controller method, is used in this research. The nonlinear AUV equations of motion are linearized in-depth plane and QFT is used for controller design for this system. System stability is considered in the design process. The performance of the P-PD controller designed by the robust QFT method is simulated numerically on the original nonlinear equations of the system. The simulation results show that the designed P-PD controller using QFT offers robust stability, disturbance rejection, and proper reference tracking over a range of AUV parametric uncertainties.

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