中文摘要：

基于一种新的计算机辅助变量几何法，以新型3-dof（3自由度）3-UPU并联机床为对象，加工具有任意复杂形状的工件以及在任意3D自由曲面或平面上刻字。通过几何约束和尺寸驱动技术，先建立3-UPU并联模拟机构，再构造任意3D自由曲面和刀具轨迹的引导平面，与3-UPU模拟并联机构合成，得到用于加工任意3D自由曲面的模拟并联机床。给定加工路径，各驱动杆长和动平台的位置能自动求解出来。通过解析的方法验证对比，得出计算机辅助变量几何法不仅简单直观，而且省去了大量的编程计算。

英文摘要：

A novel computer aided geometric approach is proposed for machining a complicated shape workpiece and lettering on a 3D free surface or a plane by adopting a novel 3-UPU parallel machine tool. Based on the geometry constraint and dimensiondriving technique, a 3-UPU parallel simulation mechanism is created. Then a 3D free surface and a guiding plane of tool path are constituted, with the 3-UPU parallel machine tool combined, a novel 3-UPU simulation parallel machine tool for machining a 3D free surface is created. By controlling two driving dimension on the guiding plane, the process of machining is complfted. From the simulation results, the approach can be used to machine any unknown surface without compiling computer program, and is also advantageous from viewpoint of accuracy and repeatability.