Research And Development Of A General CNC Platform Based On RTLinux

With the development of PC technology, the computer numerical control system is entering a brand-new stage——software CNC. Software CNC means that all the functions of CNC system, such as interpolation, position control and PLC are implemented with software modules. Comparing with traditional CNC, software CNC has a better flexibility, versatility, efficiency and openness.In the thesis, the hardware platform of the system is PC104, and the software platform of the system is RTLinux which is a genuine hard real-time and free operation system. RTLinux is able to schedule many real-time tasks, and it meets the demand of the CNC tasks which need high real-time. Constructing all software general CNC platform based on RTLinux makes the following development of the CNC system which has the proprietary intellectual property rights easy, and it is helpful in raising our country CNC technical level.After the analysis and comparison of popular structures of software CNC systems, an open architecture CNC system with three layers is designed based on RTLinux. In addition, the methods used in the communication of layers and modules are designed according to the resources of Linux and RTLinux, and the interface protocol among modules is designed and defined according to the data and commands streams of CNC system. The Linux kernel and the RTLinux kernel are customized according to the demands of CNC system, and the particular replanting processes on PC104 are introduced too.To improve the stability and running efficiency, Qt is used in the development of the graphical user interface, and C language is used in the development of the management layer and control layer. The system running on FrameBuffer without the supports of the Linux desktop and XLib reduces the demand of the memory and the storage.Finally, the debugging and development of application program and kernel program are introduced. The system has been tested on PC104, and the result shows that the main functions of the CNC system can meet the expected design demands well.