Performance Evaluation of Four-Bar Linkages for Rigid-Body Guidance Based on Generalized Coupler Curves

The concept of generalized coupler curves of linkages is introduced in this paper. Using this concept, the study of path generation and rigid-body guidance can be done within the same framework for analysis, synthesis and optimization of linkages. Moreover, a unified method of performance evaluation for rigid-body guidance is presented, that is applicable to four-bar linkages of any type, as long as the linkages have quadratic input-output or input-coupler functions. The method is an extension of the performance-evaluation method for path generation introduced in a previous paper. That method is based on the usual coupler curves, and hence, is only applicable to path-generation problems. The present method is based on generalized coupler curves, and is, thus, applicable to the problems of both path-generation and rigid-body guidance. It is oriented towards the iterative optimization of rigid-body-guidance tasks with four-bar linkages, and hence, considers numerical complexity as a determining issue. Numerical examples in which the method is applied to a planar four-bar linkage and a spherical four-bar linkage are included.