Developing And Research Of Error Compensation Controller Of CNC

From the mid of 1990s, with further research on software error compensation and implementation of the method by many researchers, many references and technology aiming at improving the machining precision came out continually. The result of research showed a good future for software error compensation method. Software error compensation depends on various algorithms designed by different scientists. Before software error compensation method, scientists used traditional mechanical methods to compensate the error.At present, many CNC machine tools are compensated by an additional PC and some auxiliary sensors. Although this method can fulfill compensation, it demands stricter working condition and more assistant equipments and is complicated to debug and costs more. These defects lead to the failure of software error compensation method to be manufactured and marketable. According to issues mentioned above, this paper develops an error compensation device controlled by MCU (Micro Control Unit) which combines the advantages of software error compensation method and IC (Integrated Circuit). The device can compensate the error with programs solidified in MCU and communicate with CNC Machine tools through RS-232C interface. With a small size, the device will be valuable for its function, flexibility and marketability.Based on multi-body system theory, this paper firstly establishes the model of ZK7640 which includes geometric error parameters, and the equations for precision machining are given. Besides, the nine-line method with which CNC machine tools error parameters is distinguished and the method of error parameters preprocessing are introduced.Secondly, the general design concept of error compensation device including hardware and software is depicted briefly. Hardware design contains divide of different modules, function and type selection of MCU and other important chips, schematic design of major and peripheral circuit and PCB design. PCB design deals more with the package of chips, routing and anti-jamming design.Then the paper places emphasis on software design. Software is crucial for the device and determines its performance. Dividing the modules in accord with hardware design, flow chart design and definition of system parameters are three major aspects of work. The program is designed with C language with assistance of assemble language, and some parts of source code are given.At the end of paper, debugging methods are presented. Hardware and software of the device must be debugged separately, and after both have no bugs, the device can be debugged online. The result finally shows the validity and accuracy of geometric error compensation controller developed in this paper.