Study Of Virtual Prototype Of Tool System For Compliant Polishing Of Aspheric Parts

With the development of modern electronic and optical technologies, researchers'attention is collected by aspheric optical parts for its excellent optical properties. As is known to all, the surface quality determines the using value of optical parts. So far, the optical polishing finished in high-precision instrument, which will make a substantial increase in processing cost, and restrict the widespread use of aspheric parts. In order to reduce the manufacturing cost of aspheric parts, a new method of aspheric manufacturing and tools based on the common NC lathe is studied. Undoubtedly, it has theory meanings and project value for the widespread use of aspheric parts.Because the machining accuracy of common NC lathe is not high enough, polishing can be carried out working with an additional tool and compliant control. One nodus of the compliant control is the force/position coupling in the force/position hybrid control, i.e., there exist different tool poses at the different positions and also need various polishing force servo in processing. The polishing force has something to do with the processing station, which will make a great difficulty to design a force servo control system. In this thesis, a method of decoupling the force/position hybrid control is proposed. In specific word, with the proper force servo and motion track, the direction of polishing force is kept same to the normal direction of parts'surface, and force can be controlled independently of position. At the same time, a tool system which is fixed in the common NC lathe is designed to study the aspheric manufacturing method. Generally, servo motor or hydraulic mechanism is used as force servo, whose force providing depends on the displacement. To meet the control of force servo, a new type of torque servo system consisted of Magnetorheological Fluids (MRF) damper and servo motor is proposed. For the advantage of rapid response and damping adjustable stepless of MRF damper, it will play a good role in the force servo in the active compliant control.In this thesis, using the virtual prototyping technology and the strategy of force/position hybrid control decoupling, a simulation equivalent model of MRF and the virtual prototype of the tool system are established in the kinematics and dynamics simulation software ADAMS. After analyzing the structure of the polishing tool, optimization which is validated by simulation outcome and experiment is put forward. Then, A mathematical modeling for operation space of the tool system is built. According to the simulation outcome, a control system is designed based on the dynamic model of the tool system to improve the force output stability of the tool system. ADAMS and MATLAB/SIMULINK co-simulation shows that the force servo property of the tool system has been improved with the control system.