On the Design of One-DOF Planar Parallel Motion Generators with Revolute Joints Only
Date Issued
2011
Date
2011
Author(s)
Chen, Jing-Heng
Abstract
A design methodology for the one degree of freedom (DOF), all-revolute, planar, parallel motion generators (PMGs) is proposed, where two non-adjacent links of the linkage are designated as parallel links, for which the relative orientation between the two links is kept constant at all configurations of the linkage. The relation that holds the paired links to have invariant relative angle is an additional motion constraint given to the system by the designer. In general, while any auxiliary constraint is imposed, a multiple-DOF planar linkage may lose one of its DOF’s and a one-DOF linkage may turn into an over-constrained linkage which can proof by Grubler–Kutzbach equation. By adjusting the number of independent links and independent loops, the over-constrained linkage will have the same behavior as the one-DOF linkage, and the special geometric conditions for PMG could be obtained.
Elaborate the overall concept of the method with four-bar linkage firstly, and add the difference between multiple-loops and single-loop linkage with the aid of the example of six-bar linkage, finally, for the purpose of generalized of the method, examples of eight-bar linkage are demonstrated. Classify all admissible assignments of parallel links in eight-bar linkage into several types, and take one example of each type of admissible assignments.
Subjects
Parallel Motion
One Degree of Freedom
Over-Constrained
Planar
Type
thesis
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