Fuzzy Controller used Smoothing Function for Depth Control of Autonomous Underwater Vehicle

Autonomous Underwater Vehicle (AUV) is a typical system which is characterized by nonlinearity, uncertainty of system parameters, and it is also affected by many external disturbances. Therefore, it is difficult to achieve the accurate AUV motion control, which includes depth control, heading control and so on. In order to improve the stability and robustness of depth control system of AUV, this paper researches the model of AUV's motion, analyzes the characteristics of the main existing methods for AUV depth control, including PID, variable structure control (VSC) and fuzzy logic control (FLC). Then, a new method of fuzzy controller used smoothing function (SFFC) for depth control of AUV is proposed based on VSC and fuzzy logic. Finally, simulation and comparison experiments based on dynamic model of AUV are carried out to verify the validity of this method. The results show that the SFFC has better stability and robustness for AUV's depth control system than VSC and PID control.