Evaluation of Mechanical Response of Human Palm to Small Impact Force

Abstract

Method of measuring mechanical characteristics of human palm against small impact force is proposed. Medical doctors qualitatively evaluate the mechanical characteristics of the human body by manipulation and percussion. In the field of bioengineering, accurate quantitative analysis of the mechanical characteristics of the human body is required. In this paper, the mechanical characteristics of a human palm against small impact force are determined by means of the Levitation Mass Method (LMM). The LMM is a method for accurately measuring varying forces without the use of force transducers. Mechanical characteristics of a human palm were measured with high accuracy by means of an instrument based on the LMM. In the measurement, the mass, that is a moving part of an aerostatic linear bearing (a hydrostatic linear air bearing, an externally pressurized air bearing), is made to collide with a human palm under test. During the collision measurement, only the Doppler shift frequency of the laser light reflecting on the mass is highly accurately measured using an optical interferometer. The velocity, position, acceleration and inertial force of the mass are calculated from the measured time-varying Doppler shift. The mechanical response of a human palm against small impact loading is also characterized from the measured data.