Multi-axial-loading calibration for the instrumented golf grip handle

Abstract

During the golf swing motion, the upper limbs and a club make a closed multi-segment loop, where it is impossible to calculate the forces and moments exerted by each hand via inverse dynamic calculation due to the kinetic redundancy of the closed loop system. An instrumented grip handle equipped with twelve sets of strain gauges was proposed and designed by the author to measure the forces and moments exerted by each hand. The purpose of this study was to clarify the validation of the multi-axial calibration method, using a force platform, for the instrumented grip handle developed for kinetic analysis of each hand during golf swing motion. A coefficient matrix, which relate the sensor output voltages of the bending strain gauges to the bending moment exerted on the location of an attached strain gauge, was identified using the information of exerting moments measured with the force platform. Crosstalk components were also considered in the calculation of the coefficient matrix. The validity of the proposed calibration method was clarified by comparing the acting forces on the top of the handle to the forces measured with the force platform. The results obtained in this study showed the errors of forces between that calculated from the instrumented grip handle and that measured with the force plate showed smaller than those obtained from the single-axial calibration method.