Tracking control of underwater vehicle subject to uncertainties using fuzzy inverse desired trajectory compensation technique

Computed-torque controller plus fuzzy inverse desired trajectory compensation technique based on robust adaptive fuzzy observer is proposed to control underwater vehicle subject to uncertainties. A fuzzy inverse desired trajectory compensator is developed as a nonlinear filter at input trajectory level outside the control loop to address the issue of unavailable normalizing factor. A robust adaptive state observer with loose constraint on the position of the uncertainty function is proposed to evaluate the unavailable states. Numerical simulation results of regulation performance demonstrate that the observer solves the problem of strict constraint conditions on position uncertainties. Comparisons of tracking performance between the proposed control method and computed-torque controller are performed. The results confirm that compensation at the input trajectory offers better position tracking performance and easier practical implementation than other fuzzy compensation techniques at joint torque level. The proposed control approach is simulated and its efficiency is validated through the simulation of an underwater vehicle.