Adaptive backstepping sliding mode control for surge motion of an autonomous underwater vehicle

The adaptive backstepping sliding mode control is proposed for the surge motion control problem of an autonomous underwater vehicle (AUV) affected by previously unknown constant current which is not properly dealt with in the previous researches. Recognizing the feedback structure of the surge motion model, the adaptive backstepping technique is used, and the unknown current and hydrodynamic coefficients are estimated by adaptive laws. The sliding mode control is introduced to deal with the uncertainties not included in the model. The surge position tracking error is proved to be globally asymptotically stable. Finally, the simulation results are presented to demonstrate the stability and adaptability of the proposed controller.