Design Of Pressure Control System For The Head Of Large Scale Optical Polishing Robot

Large-diameter aspherical optical polishing is a complex process, for it involves many areas and disciplines. With the development of technology, in order to meet the growing needs of scientific research and national defense modernization, the demand for large aspheric optics grows day by day, the requirement for the accuracy of the optical element increasingly high and caliber increasingly require optical elements to greater. Currently, foreign large-diameter optical aspheric polishing and polishing equipment technology is relatively mature, but China is only just started, therefore, it’s important for us to develop the technology of large-diameter aspherical optical polishing. The project aims to develop polishing pressure pneumatic control systems for the polishing robot, which is composed by SIX-DOF manipulator and planetary polishing grinding.This paper improved and perfected its pneumatic control system based on the first-generation polishing robot, it solved the problem that the polishing pressure Low pressure feedback control was unstable and inaccurate. First, According to large-caliber aspherical optical elements of the actual processing needs, based on the planet type rotational structure, a kind of dual pressure balanced polishing pressure control system was proposed in this paper. The closed-loop pressure control system was built, which used two electrical proportional valves and pressure sensors. The nonlinear mathematical model of the pressure control system was built by analysising experimental values. In order to output constant pressure, a composite controller was developed combined with Feedforward control and multiple sets of bimodal PID control. Second, in order to meet the work requirements of polishing grinding modular, the circuit for polishing grinding control system and control cabinets was designed by OUTCAD. Finally, designed program on the motion controller and pressure detection device to control the polishing pressure, at the same time, a communication interface was degined by C# on computer which was used to observe and control the working status of the system.In order to test the working performance of the control syetem, the experimental Platform was built. The steady-state error、low stability and dynamic response of the system was tested by the manipulator joint commission in. Experimental results show that the control systrm can achieve grinding pressure smooth transition. The output of the pressure is adjustable within the range 0 to 350 N and the steady pressure fluctuation is less than 1N. The system has good robustness against the enous disturbances piston of cylinder. System basically meet the stability and accuracy requirements of polishing pressure.