| The parallel machine tool (PMT) driven by the multi- poles parallel structure , has many superiorities to traditional machine tool such as high rigidity, light quality, high velocity, high accuracy and so on. Different from the traditional machine tool based on linear displacement on Cartesian coordinate axes, the PMT whose processing movement is a non-linear mapping of the driving poles'displacement in joint space, is more complex to control. The PMT CNC system bases on open system architecture is a perfect solution to the diversity of kinematics principle and transformation between actual (joint) and virtual (Cartesian) space of PMT, and is conducive to algorithm for control both in experiments and explorations.Combined with the new 3-TPS PMT CNC system researching and developing project, this paper studied several kinds of structures of open CNC system and structures of the existing PMT CNC systems, and analyzed the characteristics and requirements of PMT CNC system, and designed the open system architecture of CNC oriented to the PMT. The strategy of the PMT control, which contains two levels of interpolation both in virtual and actual space, was designed according to analysis and summarizing of the PMT control's characteristics. Methods of tool length compensation in five axes linkage were discussed, and a new approach of tool length compensation carried out in kinematics transformation was put forward. Speed verification in five axes linkage was analyzed. Aimed at the motion speciality of the 3-TPS PMT, follow-rotation of the table and the pursuing motion of the tool in five axes linkage was discussed, and the corresponding speed verification and restraint algorithm was produced.Finally, the paper introduced 3-TPS PMT CNC system based on the LT-NC110 hardware platform, and the partial algorithms discussed in the paper were simulated and confirmed.
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