Autonomous Underwater Vehicle Heading Control Based on Sliding Mode Fuzzy Control

The autonomous underwater vehicle dynamics model is hard to be built because it is suffered from uncertain disturbances. The sliding mode fuzzy control method is used to solve this problem. The rules table of fuzzy logic controller is determined by open loop step response for maximal and minimal rudder. Each rule of fuzzy logic controller is a sliding controller. The system control function is determined by output of fuzzy controller. And thus approximation property of fuzzy logic control and robustness property of sliding mode control are combined. Taking a AUV for example, its controller is designed by this method and is tested by computer simulation with comparing to proportional-derivative control. The computer simulation is done by simulink of matlab. The result proves that when the current disturbances existing, the AUV's overshoot will become bigger and even lose stability under proportional-derivative control. But under sliding mode fuzzy control, the AUV will keep steady state and sailing as desired. The system's chattering is alleviated and robustness is improved.