Research On The PWM Robust Control Of Water Hydraulic Underwater Manipulator

The water hydraulic two-joints manipulator designed and researched in this thesis is driven by water hydraulic cylinder and PWM high-speed solenoid valves. The robust controller is used that can decrease the effects of cylinder friction characteristics.This thesis describes the arm mechanical structure, kinematics and dynamics models of the manipulator as well as the hydrodynamics characteristics of water hydraulic system. All these give rise to the overall dynamic model of the water hydraulic manipulator.With regard to the non-linearity and uncertainty of the water hydraulic manipulator system, the control method is researched in reducing the impacts of friction of the water hydraulic cylinder on the manipulator control. PWM control solenoid valves are used to reduce the negative effects of the non-linear signaling transfer of water hydraulic system. The adverse effects of the friction characteristics uncertainty are suppressed by researching the compensation of a certain kind of robust controller for the bounded unknown parameters.The friction characteristics experiment of the water hydraulic cylinder was conducted which resulted in the range of values of the dynamic and static friction. By inserting the parameters into the controller, the robust control experiments were accomplished. The results show that this controller can finish the kinematic control of the manipulator. However, the control quality can be better performed with the further improvement of the response frequency of self-made digital valve.