Research And Implementation Of CNC Hardware Interpolation System Based On FPGA

The structure of "MCU+FPGA" is adopted in the CNC hardware interpolation system to reduce the complexity of traditional hardware interpolation circuit, also it is overcome by using software interpolation the shortcoming of low speed, poor real-time, low reliability, it can also take advantage of the characteristics of FPGA with repeated programming to realize the reconstruction of the system to facilitate the development of open CNC system requirements. MCU, as the core control chip of hardware interpolation system, is mainly used to control the start, stop and data transmission.Because the internal procedures are written in C language, the program of readability and portability is increased. FPGA, as the core chip of hardware interpolation system, is used to complete the interpolation work of the entire numerical control system. The modular design concept is adopted in this hardware interpolation system, the ISA bus module, the dual-port RAM module, the MCU module, the FPGA interpolation module, the voltage conversion module and the configuration of FPGA module, etc. In the Quartus119.0environment, using the principle of DDA interpolation algorithm, the procedures of linear interpolation, the procedures of arc interpolation, the composite interpolation procedures of linear and circular, the composite interpolation procedures of circular and circular are written in VHDL language, then the interpolation module is generated after compiling and simulating, and these interpolation modules are connected to create schematics. The acceleration and deceleration control and the feed rate control are achieved by using the accumulation and frequency division method in the FPGA. A host computer and motion control card data communications is achieved by using the dual-port RAM. The problmes of communication software programming of the host computer software and motion control card in C++Builder have been resolved by introducing WinIO components.The result of the debugging shows that the CNC hardware interpolation system can not only complete the general linear circular interpolation, but also complete the linear and circular composite interpolation and the circular and circular composite interpolation function. The Characteristics of repetitive programming of FPGA makes the hardware interpolation circuit as convenient and flexible as software, thus the reconstruction of the system can be realized by changing device programming momentarily. Or modify the interpolation function according to the needs of further improvement, which greatly facilitates the maintenance and upgrading of the system, thus it shows the system maintenance and upgrades.