Computing the friction forces associated with a three fingered grasp

This paper formulates the static equilibrium equations for grasping a general solid object using a three fingered mechanical hand. The contact between the fingers and the object is modeled as point contact with friction. The primary result of this work is a procedure which allows the computation of the friction forces required to satisfy equilibrium for a known set of contact normal forces. By comparing these friction forces to the maximum sustainable between the contacting surfaces, we can determine if the object will slip from the grasp and further we have the twist which characterizes the slipping mode. Two examples are solved in detail to illustrate the procedure.