A Hand Posture Measurement System for Evaluating Manual Tool Tasks

Abstract

A measurement system of describing the loads in the hand during manual tool tasks is presented. The system consists of a network of force sensitive resistors and an angle transducer glove (CybergloveTM, Virtual Technologies). Eighteen different cylindrical grip tasks for six subjects were studied using the developed measurement system. Fourteen flexion and abduction angles and the ten force data from ten locations of the hand was measured for the sixteen tool tasks. The results showed that the flexion angle for the five fingers decreased with increasing grip span. Grip force was mainly controlled by the opposing action of the thumb and the index finger. The contribution of the thumb and index finger force to the total grip force was greater when the grip size was increased. A regression approach to estimate the joint flexion angle based on the hand anthropometry and grip characteristics showed significant results. It was possible to use the data from the measurement system as an input to the calculation of the joint torques and moments in the finger joints. The simultaneous measurement system of the finger joint angles and finger forces was useful in collecting the information on the hand force postures during the duration of the task. The system was also useful in providing detailed input data for the biomechanical analysis of the hand.