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Machine Theory
Mechanism and Machine Theory 43 (2008) 391–399
ate/mechmt
Myard’s first five-bar linkage as a degeneracy of a
plane-symmetric six-bar loop
J. Eddie Baker
School of Information Technologies, The University of Sydney, NSW 2006, Australia
Received 18 September 2006; received in revised form 15 November 2007; accepted 19 November 2007
Available online 6 February 2008
Abstract
Among the best known of overconstrained kinematic loops, Goldberg’s generalised five-bar is also recognised as a ‘‘par-
ent” linkage to Myard’s first five-bar of 10 years earlier in appearance. Somewhat oddly, despite both having been synthes-
ised from t chains, the latter is plane-symmetric and the former essentially asymmetric in character. Explored in this
paper is the notion that Myard’s linkage might be alternatively sought as a derivative of a plane-symmetric six-bar. Whilst
there is high expectation of ess in this instance, the approach may offer broader application. As well, the analysis high-
lights technical features of significance to workers in the field of linkage kinematics.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Linkage kinematics; Overconstrained linkages; Linkage mobility; Displacement–closure equations; Screw-vector algebra;
Spatial linkages
1. Introduction
Notwithstanding the many recorded solutions [1–3] o