Analysis of frictional forces in indeterminate enveloping grasps

The problem due to the statically indeterminate contact forces arising in indeterminate frictional enveloping grasps is addressed. First, we show that the statical model for the contact forces is incomplete in the sense that the mathematical frictional forces may have an infeasible component. To resolve this infeasibility, we directly derive the enveloping grasp infeasibility condition on the frictional forces based on the coordinate transformation developed for frictional enveloping grasps. Then the indeterminate grasp can be analyzed in cooperation with the enveloping grasp feasibility inequality, as shown in a numerical example.