| Ultra-precision machine tool is a key equipment of national production, reflecting the industrial development level. Ultra-precision machine tools are capable of processing Micron and even Nano structure. It’s mainly for optical parts machining, precise micro parts machining, etc. The equipment of Ultra precision machine tool is a systematic project. From the perspective of development, the control system is related to to the processing of response characteristics of the system. Compensation of controller and motor-driven characteristics will affect the surface quality of the Workpiece. From the maintaining perspective, characteristics of electrical system changes with its aging and loss, and it is difficult to quickly identify PID tuning parameters. In addition, the changes of temperature, load and pressure cause changes in control characteristics of the machine tool. PID control parameters must be adjusted with these changes. Manual tuning method is inefficient and further costlyIn order to improve the performance of Ultra-precision system, UMAC is employed as controller of machine tool numerical control in the present paper, selection, parameters matching and optimization of control hardware are completed, as well as the construction of the hardware platform. A human-machine interface is developed with Visual Studio and, communication between hardware and software is relized by calling dynamic link library of the UMAC controller. The management of electric communication, motion state and peripheral I/O of the machine tool is relied with the software. on this basis, the dynamic responses of the existing structure are debugged with the software,and common problems are analyzed with propose solutions.Aiming at the problem of low efficiency of the PID parameters setting, system model of Ultra-precision machine tool is Firstly given according to the method of system identification. The process of modeling start with choosing the appropriate input signal according to the characteristics of mechanical system, and the order of the mathematical model which describes the system is then determined by inputting excitation. Secondly, Identification algorithm which is suitable for ultra-precision machine tools can be selected according to the characters of the noise and delay of the system. The Algorithm are Simulated and tested with the known model. Finally, the model of actual system is obtained by experiments to test and prove the validity of the model through the test method.In the process of model identification, the influence of the input frequency on the estimation of order and parameter model of the system is studied. The validity of the identification algorithm is carried out by experiments.In the premise of obtaining system model, the influence of each link on UMAC system is studied and operating process is simulated through external algorithm. Combining the system model with simulation of UMAC algorithm, the simulation of the control system is realized. On this basis, PID parameters setting is realized through the iterative search method and the revised Z-N method. At the last, PID setting software module is developed to realize the integration of system identification and PID setting In order to make parameters setting more targeted and efficiency. |
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