Computing the friction forces associated with a three-fingered grasp

A procedure is presented for computing the friction forces required to satisfy static equilibrium, given a set of normal contact forces exerted by a three-fingered mechanical hand. The contact between the fingers and the object is modeled as "point contact with friction. "This means the fingertip is free to rotate about the point of contact, but sliding along its surface is resisted by a friction force. Comparing these friction forces to the maximum friction force, which can be sustained between the contacting surfaces, it must be determined whether the object slips from the grasp and further the instantaneous motion of the impending movement. Two examples are solved in detail to illustrate the procedure.