radial polydactyly, the most common digital duplication in asian and white populations, has a wide range of manifestations. its classification is useful for planning and assessing surgical treatment. our patient had four thumbs, duplicated radial carpal bones, and a bifurcated radius. this presentation is not covered by any of the current classifications. to the best of our knowledge, this is t...

This paper presents a grasping strategy of unknown objects imitating human grasping reflex for anthropomorphic robot hands. In the proposed grasping, each joint of the thumb and the fingers is controlled independently using the contact force affecting its adjacent fingertip side link. By setting a suitable contact force, both fingertip grasping and enveloped grasping with uniform grasping force...

The muscles and tendons of the thumb are very strong but are not designed for the type of intense activity associated with many of today's handheld devices. Muscle fatigue and excessive muscle tension can cause pain and ache in the muscles and restrict the joint flexibility. Over the long term this kind of excessive use can irritate the tendons and lead to premature arthritis. The repetitive st...

It is difficult to generate the action of stably pinching paper or needle, etc. with the finger tips, which is one of the important functions to be realized by humanoid robot hands. In this paper, therefore, the authors firstly propose a small-sized and light-weight robotic hand designed according to the concept of extracting required minimum motor functions and implementing them to the robot, ...

The present study aimed to elucidate whether the type of feedback influences the performance and the motor cortical activity when executing identical visuomotor tasks. For this purpose, time to task failure was measured during position- and force-controlled muscular contractions. Subjects received either visual feedback about the force produced by pressing a force transducer or about the actual...

Advancement in assistive technology has led to the commercial availability of multi-dexterous robotic prostheses for the upper extremity. The relatively low performance of the currently used techniques to detect the intention of the user to control such advanced robotic prostheses, however, limits their use. This article explores the use of force myography (FMG) as a potential alternative to th...

Fingertip force control requires fine coordination of multiple hand muscles within and across the digits. While the modulation of neural drive to hand muscles as a function of force has been extensively studied, much less is known about the effects of fatigue on the coordination of simultaneously active hand muscles. We asked eight subjects to perform a fatiguing contraction by gripping a manip...

this deformity is often reffered to as thumbclutched hand, but a better term is the congenital clasped thumb. the congenital clasped thumb is associated with several well-de-fined syndromes, although it may also present as an isolated abnormality. weckesser, reac, and heiple called it a syndrome and divided the syndrome in to four groups. in group i, the thumb is deficient in extention only. in...

Anecdotal evidence suggests that a thumb and index finger grip might facilitate recovery from the manifestation of spatial disorientation known as the giant hand phenomenon. Sixteen pilots volunteered as subjects in an experiment that compared the effectiveness of the thumb and index finger versus the whole hand technique to overcome a visually-induced analogue of the giant hand phenomenon. Thu...