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

Abstract

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.