Applications of fuzzy logic to the control of an autonomous underwater vehicle

Describes applications of fuzzy logic to the control of an autonomous underwater vehicle (AUV). One application described here is a fuzzy logic six degree-of-freedom flight control system by the Ocean Voyager, an AUV currently under development. Heading, pitch, and depth are controlled simultaneously by three separate fuzzy logic controllers, each a function of setpoint error and error rate. An additional fuzzily constrained integrator compensates for frictional effects and setpoint error. The fuzzy controllers were tested and show good performance over a range of velocities. Another application described is a docking controller for the Ocean Voyager. This controller enables the AUV to dock with another underwater vehicle. Both moving and stationary targets are allowed. The fuzzy rule base recursively drives the vehicle toward intermediate fuzzy goals that become more precise as the final target is approached. The fuzzy goal approach does not rely on high accuracy maneuvers or waypoints. Docking proceeds as long as the AUV remains in a funnel of acceptable intermediate positions. Performance of the docking controller was tested by simulation