On Computing the Friction Forces Associated With Three-Fingered Grasp

Computation of friction forces between fingers and object for a given external force is important in grasp planning. Based on the required friction forces, the magnitudes of the grasping forces can be adjusted to avoid slippage of the object be tween fingers. This article presents a very elegant and effective method for computing the friction forces between the fingertips of a dexterous mechanical hand and the object as a function of the external wrench which can act on the object. Fingertips are modeled such that they are able to exert normal forces and are making point contact with friction with the object. The method in this article utilizes geometric information on the grasp con figuration, screw geometry, and bi-orthogonal systems. The method is demonstrated through detailed tutorial solutions of two examples.