Robust maneuvering of autonomous underwater vehicle: an adaptive fuzzy PI sliding mode control

Abstract

The control issues in nonlinear trajectory tracking of an autonomous underwater vehicle (AUV) are a challenging task due to the complex oceanic environment, highly nonlinear coupled dynamics, imprecise hydrodynamic coefficients and unpredictable external disturbances such as ocean waves, current fluctuations and tides. This paper addresses an adaptive fuzzy PI sliding mode control (AFPISMC) for trajectory tracking control of AUV to achieve high precise maneuvering in undersea environment. An AFPISMC is basically comprised of an equivalent control based on approximately known inverse dynamic model output and continuous adaptive PI term is designed to eliminate chattering effect. Furthermore, it does not require a priori knowledge of upper bounds on uncertainties in the dynamic parameters of an AUV. In this approach, decoupled single input fuzzy PI control strategy is employed along with a reduced rule base and self-tuning control law is derived to modify hitting gain in order to enhance tracking response. The overall control scheme guarantees the global asymptotic stability based on Lyapunov theory. Finally, the effectiveness and robustness of the proposed approach are demonstrated through simulation and comparison studies.