Design of polynomial fuzzy controller for depth control of autonomous underwater vehicles

The motion control of autonomous underwater vehicle (AUV) system is a very challenging issue because of the high nonlinearity, strong coupling and time-varying property. A novel polynomial fuzzy model based (PFMB) output feedback controller is proposed in this paper, which enables the AUV to achieve the desired depth quickly and stably. Specifically, a polynomial fuzzy model of AUV is constructed by considering the interaction between velocities in each direction and ensuring the pitch angle within a safe range in practical applications. Then an output feedback control strategy, based on the Lyapunov stability theory and sum of squares (SOS) approach, is designed and verified. Simulations are provided to demonstrate the feasibility and effectiveness of the proposed controller.