Construction of screw geometry via 3-D CAD system for the analysis and synthesis of spatial mechanisms

This paper investigates the application of computer-aided design and drawin g (CAD) software to the kinematic analysis and synthesis of spatial mechani sms based upon screw geometry. The advantages of the graphic method for the synthesis and analysis of mechanisms are straightforward, comprehensive, c learly represented, and easy to correlate to a real mechanism. Using conven tional 3-D CAD software, the screw axes and joint axes are constructed as v irtual parts. The relationships of joint axes that are constrained by screw geometry are the assembly conditions for the virtual parts in the CAD syst em. This paper shows that, similar to the synthesis of a planar linkage, th e synthesis of a spatial C-C dyad by the graphical method in a CAD system i s an efficient process.