Nonlinear kinematic tolerance analysis of planar mechanical systems

This paper presents a nonlinear kinematic tolerance analysis algorithm for planar mechanical systems comprised of higher kinematic pairs. The pan profiles consist of line and circle segments. Each part translates along a planar axis or rotates around an orthogonal axis. The part shapes and motion axes are parameterized by a vector of tolerance parameters with range limits. A system is analyzed in two steps. The first step conslIUcts generalized configuration spaces, called conlact zones, that bound the worst-case kinematic variation of the pairs over the tolerance parameter range. The zones specify the variation of the pairs at every contact configuration and reveal failure modes, such as jamming. due to qua!iffitive changes in kinematic function. The second step bounds the worsE-case system variation at selected configurations by composing the zones. Case studies show that the algorithm is accurate, fast, and far superior to a prior algorithm that constructs and composes linear approximations of con[act zones. keywords: kinematics, tolerance analysis, higher pairs. abbreviated title: Nonlinear kinematic tolerance analysis. Submitted to Computer Aided Design, May 2002.