PARAMETRIC KINEMATIC TOLERANCE ANALYSIS OF PLANAR MECHANISMS

We present an efficient algorithm for worst-case and statistical kinem atic tolerance analysis of mechanisms with parametric part tolerances. The algorithm derives the kinematic variation directly from the part geometry, the part degrees of freedom, and the allowable parameter var iations. It first derives a geometric representation of the kinematic variation as parametric surfaces in the mechanism configuration space. It then performs sensitivity analysis on the surfaces and combines th e results. In addition to traditional quantitative variations, the res ults reveal qualitative variations, such as play, undercutting, interf erence, and jamming. Our implementation handles planar mechanisms with one degree of freedom per part, including ones with higher pairs and multiple contacts. It is fast enough to be practical for full parametr ic models of complex mechanisms and for parametric representations of geometric tolerances, such as offsets, which typically require many pa rameters, The algorithm extends to linkage mechanisms when coupled wit h linkage analysis software. We demonstrate the implementation on a 26 parameter model of a Geneva pair and on an 82 parameter model of a ca mera shutter mechanism. (C) 1997 Elsevier Science Ltd.