A Closed-Form Approach to Coupler-Curves of Multi-Loop Mechanisms

Abstract

This paper presents a closed-form approach, based on the theory of resultants, for deriving the coupler curve equation of 16 8-link mechanisms. The solution approach entails successive elimination of problem unknowns to reduce a multivariate system of 8 equations in 9 unknowns into a single bivariate equation. This bivariate equation is the coupler curve equation of the mechanism under consideration. Three theorems, which summarize key coupler curve characteristics, are outlined. The computational procedure is illustrated through two numerical examples. The first example addresses in detail some of the problems associated with the conversion of transcendental loop equations into an algebraic form using tangent half-angle substitutions. An extension of the proposed approach to the determination of degrees of input-output (I/O) polynomials and coupler curves for a general n-link mechanism is also presented. [S1050-0472(00)01104-1]