Foundational Research On Open Architecture CNC Systems Based On Real-Time Ehternet

With the development of science and technology, CNC technology is moving towards to the direction of high-precision, high-speed, efficient, flexible, intelligent and integration. Closed CNC system is impossible to adapt flexibly to be fit for the changing market requirements because of its lack of openness. Open CNC system with replaceable hardware and software, scalable and interoperable, flexible features receive widespread attention. In open CNC system based on field bus, the communication between the master controller and the slave movement module not only make the module flexibly expand also need to meet the real-time and motion control synchronicity. So the research on the methods of communication is very important. In addition in the software design process, it need analysis the NC system function module and use the COM components to realize the modular design. And motion control module is the core of the control software, the study on motion control module will to improve the performance of the CNC system. The curve interpolation technology research will be able to make the system directly process curve, so as to improve the machining precision and processing efficiency. This article will focus on communication mode and curve interpolation technology.In the study course of communication, through compared the advantages and disadvantages of the variety of real-time Ethernet in the communication rate, the real time and synchrony, real-time Ethernet EtherCAT with the international standard which meet openness requirements, real-time and synchronicity requirements is decided as the communication mode of the open CNC system. EtherCAT with characteristic of the open standards has high real-time transmission rate and high Ethernet good synchronicities. Its high real time capability can over come the slow transmission rate, the poor communication quality and the lack of openness in traditional pulse and analogue transmission way. It is suitable for open CNC system. At the same time through research to communication protocol, working principle and data frame structure of the EtherCAT in order to lay the foundation for the design of the control software.In the research process of the curve interpolation technology, through compared the quality between the linear interpolation and the curve interpolation in the curve process, this paper puts forward directly curve interpolation technology. Through research on parameters increment, the Taylor first order and the Taylor second order interpolation algorithm, put forward on the adaptive b-spline interpolation algorithm. This algorithm can control adaptable speed by high error, according to the curvature of the curve and interpolation length. The algorithm not only can improve more interpolation precision but also change the interpolation speed smoothly.the open NC system based on real-time Ethernet EtherCAT is built with the study on the key technology and design the control software based on the EtherCAT. At end, test the platform of multi axises linkage and test host control software function, The results show that the numerical control system platform with open CNC system design goal, master station control software is feasible.