Minimum-Deflection Grasps and Fixtures

This paper presents an approach to planning compliant grasps and fixtures in which the object exhibits minimal deflection under external disturbances. The approach, which applies to general twoand threedimensional grasps and fixtures represented by any quasirigid compliance model, employs a quality measure that characterizes the grasped or fixtured object’s worst-case deflection caused by disturbing wrenches lying in the unit wrench ball. To ensure well-defined notions of deflection and wrench balls, frame-invariant rigid body velocity and wrench norms are for the first time used. As illustrated by its application to fixtures of polygonal objects, our minimum-deflection approach can be effectively applied to planning grasps and fixtures where deflection significantly influences performance.