A fuzzy model-based controller of an underwater robotic vehicle under the influence of thruster dynamics

Underwater robotic vehicles (URVs) have become an important tool for various underwater tasks because they have greater speed, endurance, depth capability, and safety than human divers. Many URVs powered by electric motors driving propellers. The thruster system is known to be nonlinear and time-varying The system dynamics of URVs can be greatly influenced by the thruster dynamics at low speed or stationkeeping. Good control of a vehicle at low speed is also an important design problem which must be solved to permit important operations like automatic docking and combined vehicle-manipulator control. The conventional linear controller based on the simplified vehicle dynamics may not be able to handle these properties and result in poor performance. This paper describes a fuzzy model-based controller of an underwater robotic vehicle with the influence of the thruster dynamics. The fuzzy controller presented in this paper is based on a Tagaki-Sugeno-Kang (TSK) fuzzy model and guarantees the stability of overall fuzzy control system Its superiority to the conventional linear controller is investigated by computer simulation.