Kinematic Mapping Based Assembly Mode Evaluation of Planar Four-Bar Mechanisms

[+] Author and Article Information
Hans-Peter Schröcker1

Institute of Basic Sciences in Engineering, Unit Geometry and CAD, University Innsbruck, A-6020 Innsbruck, Austriahans-peter.schroecker@uibk.ac.at

Manfred L. Husty

Institute of Basic Sciences in Engineering, Unit Geometry and CAD, University Innsbruck, A-6020 Innsbruck, Austria

J. Michael McCarthy

Department of Mechanical Engineering, University of California, Irvine, CA 92697

Note that is no restriction of generality to assume one of the input poses is the identity. This can always be achieved by a suitable coordinate transformation in the fixed frame.


Corresponding author.

J. Mech. Des 129(9), 924-929 (Jun 21, 2006) (6 pages) doi:10.1115/1.2747635 History: Received November 25, 2005; Revised June 21, 2006

This paper presents a new method to determine if two task positions used to design a four-bar linkage lie on separate assembly modes (circuits) of a coupler curve, known as an “assembly mode defect.” The proposed approach uses the image space of a kinematic mapping to provide a geometric environment for both the synthesis and analysis of four-bar linkages. The devised algorithm allows assembly mode decisions at an early design stage without resorting to the mechanism dimensions. The numerical effort is low compared to existing solutions.

Copyright © 2007 by American Society of Mechanical Engineers
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Grahic Jump Location
Figure 1

The intersection curve C has two affinely finite branches: one branch or two affinely infinite branches

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Figure 2

The two branches of the intersection curve C can be distinguished by the orientation of the triangles m1m2q1 and m1m2q2

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Figure 3

Input positions and four bar to C23 (non-Grashof) for Example 1

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Figure 4

Input positions and synthesized four-bar (crank-rocker) for Example 2

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Figure 5

Input positions and synthesized four bar (double-crank) for Example 3



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