Static analysis of two-fingered grips

Abstract

In the paper a static analysis of two-fingered grips is presented. Importance of grasp analysis in human performance engineering and hand therapy is discussed and assessment methods are proposed. Two precision grips were examined in the study: nippers pinch and tip pinch. We have built a grip-measuring device assessing the endpoint forces of two-oppositional grips. The instrument developed is based on a robotic force-wrist sensor and designed to suit human fingers. Through the simultaneous use of an optical measuring system and the grip-measuring device, the finger positions and the grip force acting on the object were obtained. A static model of the hand was also developed. A recursive computational method was used to calculate the joint torques of the fingers from the measured coordinates and the endpoint force vector. The estimated joint torque corresponds to the amount of load on the tendon during isometric muscle contraction. The force output of the two grips considered is presented and compared in two healthy individuals. The calculated joint torques for the index finger and thumb are presented and the maximal values of the finger joint torques acquired in the study are shown.