Nonprehensile Two Palm Manipulation with Non-Equilibrium
Transitions between Stable States
Nina Zumel and Michael Erdmann
Proceedings of the 1996 IEEE International Conference on Robotics
and Automation, Minneapolis, Minnesota, pp. 3317-3323.
Abstract
Manipulation without prehension is a natural way of handling objects
for both humans and machines. Nonprehensile operations are
appropriate when complete constraint over the object to be manipulated
is either undesirable or impractical, but some control over the object
is desired over its entire trajectory, in order to bring the object
reliably to a desired final state. Research to date has explored only
a small portion of this class. We are interested in controlling the
shape of the constraint surfaces so that constraint and external
forces naturally attract the system to the desired state, even if the
object momentarily loses stability during the motion. We present a
preliminary analysis of the nonprehensile orientation of planar
objects by two low friction palms joined at a central hinge. These
palms support an object in a gravitational field, without grasping or
gripping. We determine connected regions of stable states of the
object, and give a method of planning part orientation based on a
graph search over these regions, allowing non-equilibrium transitions
between them. We conclude with the results of simulations and
tests of an example plan.