Adaptive fuzzy exponential terminal sliding mode controller design for nonlinear trajectory tracking control of autonomous underwater vehicle

This paper addresses an adaptive fuzzy exponential terminal sliding mode trajectory tracking control design for autonomous underwater vehicle (AUV) using time delay estimation. The proposed control scheme assures quick convergence due to a nonlinear expression in to an integral augmented sliding surface results in nonlinear sliding mode termed as integral-fast terminal sliding mode control (IFTSMC). Furthermore, control law requires no prior knowledge about highly nonlinear underwater vehicle model due to the time delay estimation method. Meanwhile, fuzzy logic system incorporated as adaptation mechanism afford for varying switching function and adaptive exponential reaching law utilized for faster reaching time in path tracking control performance. Finally, the effectiveness and robustness of the proposed control strategy are demonstrated through numerical simulations with Cyclops AUV in presence of parameter perturbations and unidentified disturbances like ocean current, wave and measurement noise.