Abstract: In view of the difficulty of solving the workspace of the planar parallel mechanism without singularity position, the tedious process and the large amount of calculation, a three-dimensional spiral scanning method for the working space of planar parallel mechanism which bases on CAD is proposed. The planar parallel mechanism of n degree is decomposed into n branch chain for independent analysis. The reachable area of the end of each branch chain is obtained, and the intersection of all the reachable area of the branch chain is the workspace of the planar parallel mechanism. The model of planar parallel mechanism is established by using SolidWorks software, and the geometric feature is processed. The solution process is solved by automatic solver. The solution process is graphed, and the non singular position workspace of the coaxial layout 5R mechanism and the planar 3-RPR parallel mechanism is quickly obtained. The solution is verified by the kinematics experiment of the coaxial layout of the 5R machine.

Key words: planar parallel mechanism, Computer-Aided Design（CAD）, three-dimensional helical scan, singularity-free workspace

摘要： 针对平面并联机构无奇异位置工作空间求解困难、过程繁琐、计算量大等问题，提出了基于CAD求解平面并联机构工作空间的三维螺旋扫描方法。将[n]自由度平面并联机构分解成[n]条支链进行独立分析，得到每条支链下末端执行器的可达区域，再将所有支链可达区域取交集即为平面并联机构工作空间。应用SolidWorks软件建立平面并联机构模型，进行几何特征处理，通过自动求解器求解，将求解过程图形化，快速得到同轴布局5R机构和平面3-RPR并联机构的无奇异位置工作空间。通过同轴布局5R机构的运动学实验，验证了该求解方法的可行性。

关键词: 平面并联机构, 计算机辅助设计（CAD）, 三维螺旋扫描法, 无奇异位置工作空间