Trajectory Tracking Control for Autonomous Underwater Vehicles Based on Fuzzy Re-Planning of a Local Desired Trajectory

This paper investigates the trajectory tracking control problem for autonomous underwater vehicles whose initial starting position differs substantially from that specified by the desired trajectory. This scenario is very likely to cause serious chattering in the control output, especially in the early stages, when the large tracking error is the input to the controller. A novel trajectory tracking control strategy is developed based on fuzzy re-planning of a local desired trajectory. At each time instant, a local desired trajectory is reconstructed based on the AUV's current position and that specified by the original desired trajectory at a future time. Also the control effort is computed based on the local desired trajectory, rather than the original one. Moreover, the interval between each time instant is determined by a new single-input fuzzy model, where the input is determined by the distance between AUV's current and desired trajectories and the change in the distance. Finally, the effectiveness of the new control strategy is verified by simulation-based case studies using an actual vehicle model as a necessary step prior to experimental validation.