Abstract: (Sigmoid) plane control method is an effective and simple method for the motion control of autonomous underwater vehicle (AUV). A velocity controller was constructed and analyzed by S plane control method. According to sliding mode controller (SMC), an integral S plane velocity controller with selfadapting integration step was proposed in order to make control parameters adjusted by motion state. Then a selfadapting item was improved for eliminating steadystate errors and adjusting dynamically S plane controller locally. Both pool and sea experiment results show that the improved controller is effective and the adaptability of AUV motion control is strengthened largely.  

Key words:  S(Sigmoid) plane control, autonomous underwater vehicle(AUV), motion control