The Five-axis Parallel Architecture Based On Multi-type Servo Intelligent Cnc System

NC ( the Numeric Control) system has developed into the third generation of CNC (the Computer Numeric Control),which is based on PC. Higher velocity and precision are required in designs of modern NC system, and traditional design methods of NC can not meet these demands.In this paper, key technologies of the third generation of CNC are explored deeply. And ,as practice and application, a 5-axis simultaneous numeric control system based on multi-type servo parallel structure is proposed.There are two key technologies in multi-axis simultaneous control system design. One key is the auto programming system, which can generate the codes from the demanded motion path. The other is the control system, which can compile and execute the codes exactly. Nowadays the technology of auto programming system has developed maturely and the task of the auto programming can be finished specially by some CAM software, such as Unigragh, Pro/ENGINEER, Cimatron, Mastercam and so on. Therefore emphasis of this paper is put on auto control system.The special mechanical platform is developed as the executor of this 5-axis CNC system. We applied the stepping motion servo control to three of the five axis and applied the alternating current servo control to the rest two axis. Three methods of control, including open cycle control, half closed loop control and closed loop control, are all applied in this system.The control system is based on IPC(Industrial Process Control), in which the control scheme of principal and subordinate is adopted. IPC, as the principal, accomplishes the first offline interpolation and handles other important tasks. A intelligent motion controller, as theillsubordination, finishes the second accurate interpolation. Two types of servo control systems are applied in this system. One is the stepping motion servo control system. The other is the alternating current servo control system. Considering the reason of economy and sophistication, two types of servo control systems are kept both in the system. The alternating current servo control system is the trend of the servo system. On the basis of research on the principle of the alternating current servo control and the stepping motion servo control, co-existence of the two different intelligent motion controllers is realized successfully.We propose a new algorithm of two times interpolation. The principal computer accomplishes the first interpolation and puts these data to the extended memory. Secondly, the subordinate controller carries out the realtime interpolation with support of the interrupt technology.The design of this system also shows good flexibility. Modularized design hardware and software make it possible to put up CNC system flexibly with one axis ,two axis ,three axis . four axis or five axis. Furthermore, the CNC software can be transplanted to other system without any change.