fuzzy logic based flight control system for the FAU "Ocean Voyager" autonomous underwater vehicle

The development of a Flight Control System for a non-linear six degree of freedom model of an Autonomous Underwater Vehicle is described. Heading, pitch and depth are regulated by three independent Fuzzy Logic Controllers (FLCs). Numerical methods are used to tune rule bases to control tables that are based on the minimum time characteristics of the model. Setpoint errors are eliminated using fuzzily constrained integrators. A scheme to vary control policy with forward speed is also detailed. System stability is evaluated using cell-to-cell mapping. A variable structure fuzzy heading controller is designed for an unstable non-linear model of an Unmanned Underwater Vehicle. Scheduling of scaling parameters accommodates changes in forward speed as predicted by thruster RPM and angular distance turned. This FLC combines bang-bang and linear type control to respond more rapidly and robustly than a gain scheduled linear PID controller.