| Abstract | This paper presents a method to extract instantaneous artic-ulation from part geometry, based on surface mating constraints
as well as constraints imposed by other incidental contacts.
Many assemblies contain joints, each of which have degrees
of freedom associated with them. These joints allow the relative
positions of parts in the mechanism to change as the joints are
articulated. Being able to represent these joints and their behav-
ior is important from the designers perspective because it enables
him or her to verify whether kinematic requirements have been
met.Therefore, it is useful to be able to obtain such joint informa-
tion directly from part geometry and contact physics.
The method presented here handles all lower pairs of kine-
matic joints. Surface mating contacts are classified into one of
three types: planar, spherical and cylindrical. The contacts are
represented by algebraic inequalities describing the translational
and angular velocities at the contact. Non-penetration conditions
are written for a finite set of points on the boundary of each
contact face, and it is shown that the finite set of conditions is
representative of the entire boundary and the region enclosed by
the boundary. Simultaneous satisfaction of the non-penetration
conditions at all the contact surfaces between a pair of bodies is
represented by a 6-dimensional simplex, which can be solved using
linear programming.
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