Control Technology Research Of A Small Underwater Vehicle

Control system is the core of the Underwater Vehicle, which controls all theequipments and the motion. Its features directly affect the whole features of the vehicle.The dissertation introduces the design of control system, including the architecture ofcontrol system, synthetic display-and-control subsystem, motion control subsystem andnavigation system. The architecture of control system is based on Ethernet3-layerarchitecture, which is simple, stable communication, and has wide bandwidth, flexibledata structure, and the communication protocol can be modified easily. The syntheticdisplay-and-control subsystem displays and saves all the information in real time, andalarms in sound and light according to the status. The motion control subsystem hasthree pilot modes, manual mode, automatic mode and emergency mode. If theautomatic mode is trigg-ered when sailing for a long distance, the motion controlsubsystem will automatically control the yaw, depth and pitch to setting values. TheIMU, Beidou/GPS and Digital Sea Map form a redundant navigation system, and cancontrol the trace of the vehicle.The dissertation analyzes the force which is acted on the vehicle, and set up themathematical models of motions in the horizontal and vertical planes, providing basefor motion control.A variable universe fuzzy-PID controller is designed in the dissertation based onthe mathematical models for the yaw, depth and pitch automatic control. As the fuzzycontrol rules cannot be modified according to the error when established, and thecontrol performance will be weakened. With the same control rules, the universe of thevariable universe fuzzy control can be expanded with the bigger error and shrunk withsmaller error, making more accurate control effects. Simulation experiments are takenfor the yaw, depth and pitch controllers. From the comparison results of PID controller,fuzzy-PID controller and variable universe fuzzy-PID controller, we can find that thevariable universe fuzzy-PID controller has smaller overshoot, quicker adjustmentspeed and stronger robustness. Therefore, the variable universe fuzzy-PID controllercan satisfy the requirement of yaw, depth and pitch automatic control for long-distance sailing of the small Underwater Vehicle.