This paper discusses several design issues pertaining to the design of anthropomorphic underactuated robotic or prosthetic hands. The design of the underactuation mechanism that drives the fingers is first addressed. A double-stage mechanism is proposed that includes a lever arm to couple the motion of the thumb and the fingers as well as an additional pulley that amplifies the input force. The...

A fundamental requirement for the success of a manipulation task is the capability to handle the physical contact between a robot and the environment. Pure motion control turns out to be inadequate because the unavoidable modeling errors and uncertainties may cause a rise of the contact force, ultimately leading to an unstable behavior during the interaction, especially in the presence of rigid...

Previous studies have shown that the interactions of human hand digits are influenced by internal constraints, i.e., biomechanical and central constraints. However, little is currently known about the influence of externally imposed mechanical constraints on multi-finger behavior. This study investigates maximal digit force production during fixed object and free object prehension in statics. T...

From the functional standpoint, the hand is one of the most important organs of the body. However, its significance depends largely upon the pincer action of the thumb-index. The management of traumatic lesions of the hand is nowadays' subject of numerous scientific discussions. We present here the case of a patient with a recent laceration of the central slip of the extensor tendon with bouton...

The aim of this study was to determine in monkeys if inactivation of dentate and lateral interposed deep cerebellar nuclei preferentially impairs certain movements relative to others. Constrained movements of the digits were trained with digits, hand, and elbow constrained in a cast. Simple movements were flexion of Thumb or Index. A compound movement was simultaneous flexion of Thumb+Index. An...

BACKGROUND The aim of this study was to compare postoperative immobilization techniques of the thumb metacarpophalangeal (MP) ulnar collateral ligament (UCL) in a cadaver model of a noncompliant patient. METHODS A cadaveric model with fresh-frozen forearms was used to simulate pinch under two immobilization conditions: (1) forearm-based thumb spica splint alone and (2) forearm-based thumb spi...

We studied age-related changes in the performance of maximal and accurate submaximal force and moment production tasks. Elderly and young subjects pressed on six dimensional force sensors affixed to a handle with a T-shaped attachment. The weight of the whole system was counterbalanced with another load. During tasks that required the production of maximal force or maximal moment by all of the ...

The control of hand action is commonly viewed as based on a two-level hierarchy (Arbib et al. 1985): (1) The task is shared between the thumb and a virtual finger (VF, an imagined digit with the mechanical effect equal to that of the four fingers); and (2) VF action is shared among the actual fingers. Synergies at both levels can be studied as patterns of co-variation of its elements that stabi...

  This case report presents a case of Fanconi’s Anemia with an unusual thumb polydactyly in a 2-year old boy. The extra thumb had no nail, nail bed and distal phalanx. The extra thumb had no active motion.The duplication of the thumb occurred at the carpometacarpal joint but its morphology did not match with any classification described for thumb polydactyly. Although his thumb polydactyly was ...