Adaptive fuzzy inverse trajectory tracking control of underactuated underwater vehicle with uncertainties

An independent adaptive fuzzy control system of nominal dynamics and uncertain parts is proposed to control an underactuated underwater vehicle with uncertainties based on computed-torque controller. A type of fuzzy inverse trajectory compensator as a nonlinear filter at input trajectory level outside the control loop is developed to compensate for uncertainties by modifying the desired trajectory outside the control loop and to address the issue of unavailable normalising factor. Trajectory tracking performances of the proposed control technique and of the computed-torque controller are compared. The proposed control scheme is simulated, and its efficiency is validated using numerical simulations of a 3-DOF underactuated underwater vehicle. Results confirm that the adaptive fuzzy compensator at the input trajectory level offers better trajectory tracking performances and easier practical implementation than other fuzzy compensation techniques at joint torque level.