Generalized Force Curve Shapes for Structural Synthesis of Joint Torque Systems to Produce a Desired Dynamic Motion Time Response of a 4R-4Bar

Abstract

Synthesis of a force system which will drive a linkage to have a desired dynamic motion-time response is basically a task of curve fitting the generalized force curve equation, GFS, of a force system to the generalized force, DGF, required to drive the mechanism. This design, synthesis task can be broken into two phases: 1) structural synthesis and 2) dimensional synthesis. This paper deals primarily with Phase 1; selecting which type, number of each, and between which links to attach each force device. The hypotheses upon which this paper is based are: 1) that specific linkage-force system configurations have “characteristically” shaped GFS curves, and 2) their shape must in general be similar to the DGF curve shape to obtain “satisfactory” results in dimensional synthesis. The paper presents a summary of characteristic curve shapes for joint torque in a 4R-4Bar crank-rocker mechanism, the influence of parameters on these curves, and an illustrative example of structural synthesis.