On the Form-Closure Capability of Robotic Underactuated Hands

—This paper presents a new method to study the capability of an underactuated hand to produce form-closed grasps. First, the stability behaviours of different underactuated parallel-jaw grippers are analyzed and compared according to their actuation and transmission mechanisms. Then, both notions of 1st order and 2nd order form-closure are revisited for underactuated hands, since in this particular case the assumption of fixed contacts made in the original definition is false. Therefore, constraints imposed by non-backdrivable mechanisms are introduced into the model of the whole grasp. Finally, a simple geometrical condition, necessary and sufficient for 1st order form-closure is proposed. This permits to conclude on the minimum number of non-backdrivable mechanisms required to produce 1st order form-closed grasps using an underactuated hand. Keywords—robotic hand, underactuation, form-closure, nonbackdrivability.

• Type: Conference
• Year: 2006
• Where: ICARCV
• Authors: Vincent Begoc, Claude Durand, Sébastien Krut, Etienne Dombre, François Pierrot
• Keywords: ICARCV 2006, Non-backdrivable Mechanisms, Order Form-closure, Underactuated Hand