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Parallelotriangular Mechanisms and Line Contact Constraint

The pair of tetrahedra that move with intersecting edges is a parallel mechanism with six line contact constraints; the six R-P-R-P-R joints. It is also a six legged platform that moves, albeit with legs of zero length. Such five degree of freedom joints or, conversely, ones that inhibit only one degree of freedom, are conveniently studied with simple double triangular mechanisms, of planar, spherical and spatial variety, which use them. Forward kinematics, singularity and isotropy of all three types have been obtained. However, much remains to be done concerning analysis of the spatial variety(RDTM). Of particular interest are recent results which indicate that the forward kinematics RDTM's are dual to the inverse kinematics of 6R wrist partitioned serial chains, i.e., solvable is closed form. Though some controversy surrounds this claim, confirmation (or otherwise, alas) is imminent.

V. Karakusevic, V.Krovi, P.J. Zsombor-Murray

Annual Report

Mon Jun 26 21:22:20 GMT 2000