Load sensor for a human hand

Abstract

A human hand load sensor is a strain gauge based force measurement instrument that has two platforms or handles that can be moved together with parts of the human hand, for example, a thumb and finger, or the handles can be grasped between the heel of the hand and several fingers. The instrument permits very precise measuring of strength force by supporting a movable handle relative to a base or reference handle through a flexure system which deforms predictably under shear loading as the handles or platforms are moved together. The flexure system is much like a parallel linkages made from a single block of material between a base and a movable block, and having a small deflecting beam sensing element between the base and the movable block that is isolated from influences of bending or rolling movements on the strain level. The strain energy is sensed with strain gauges that provide a signal directly proportional to the shear loading for very accurate measurements. The making of the base and movable block portions from a single block of material eliminates assembly joints, giving a greater repeatability, high linearity, less zero shift during use, less hysteresis, and more stable calibration coefficients. Further, the machining process or manufacturing process is relatively low cost and highly accurate. The one piece body is easy to calibrate. The base or platform size can be modified quite easily for a wide variety of uses.