| With the increasingly demand of ultra precision machine tools in the field of civil, defense, and space science and so on, the market demand for the precision and performance of ultra-precision machine tool has been increasing. There are a lot of factors that affect the performance of ultra precision machine tool.Hydrostatic guideway which directly influences the precicion of the machine tools is the important functional units of ultra-precision machine tools, while hydraulic system is the necessary auxiliary unit for the normal work of the hydrostatic slideway. To maintain high-precision and High-stiffness running of hydrostatic guideway, hydraulic system must be able to provide stable pressure and temperature oil for hydrostatic guideway.In view of the disadvantages of the traditional hydraulic power system which use the valve control device to adjust the pressure or flow rate required by the actuator and the Weak anti-interference ability and that the parameter tuning is difficult of the commonly used PID control in industrial control,this topic has designed a kind of hydraulic servo system for hydrostatic guideway.The system uses the drive controler with the PID closed-loop feedback control device to drive the servo motor, which drives the internal gear pump to provide a constant temperature and constant pressure lubricating oil for the hydrostatic guide rail.Through the MATLAB simulation and measurement data show that the system has the advantages of low heat, high efficiency, low noise, good dynamic response and good tracking ability, strong anti-interference ability and good robustness.In this paper, the hydraulic system of the ultra precision five axis NC machine tool is studied, and the main content includes the following aspects: (1) Deeply analysis the background the hydraulic servo system, including the shortcomings of the traditional hydraulic power system, Overview of PID control, general situation and research status of intelligent control, general situation and research status of fuzzy control. (2) Starting with the hydraulic system design, the principle diagram of the hydraulic servo system is set up, and the SolidWorks 3D modeling of the mechanical components such as oil tank, pump and motor mounting block, oil circuit integrated block is built. Selection and purchase of hydraulic components have been done, such as hydraulic components and drives, motors and other key electrical components.(2) A hydraulic servo control system has been set up, firstly the experimental measurement including the efficiency of the oil pump, the oil temperature have been done,then the step response test of the PID control system is carried out, through which the dynamic response characteristics of the pressure and the pressure fluctuation characteristic and the anti disturbance ability are obtained.(3) The principle and structure of fuzzy PID control have been deeply studied, especially fuzzying input variables and the method of fuzzy variable definition. And the parameter self-tuning fuzzy PID controller is designed for the hydraulic servo system.(4) The fuzzy PID control system model of hydraulic servo system is built using MATLAB software. After simulation analysis, it is concluded that the fuzzy PID control strategy has the characteristics of fast response, strong anti-interference ability and good robustness.(5) The fuzzy PID control system is applied to the actual hydraulic servo system, and the measured data further prove that the fuzzy PID control system has better dynamic characteristics and stability. |
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