Fastening ergonomics study based on state-space modelling of hand-arm system

Abstract

The aim of this study is to model the hand-arm as a rotational single-degree-of-freedom system during fastening operations with shear-type fasteners using state-space representation. The values of the model parameters are estimated by determining the characteristic state-space matrices from the measured tool rotation and torque data collected during the fastening operation and then using a parameter extraction algorithm to derive the model parameters in the state-space matrices. The identified parameter values are used to determine the response and the dynamic reaction force, which are used to assess the dynamic effects of tool operation on the hand-arm. The effect of posture, grip-force and tool-type variation is analysed using the dynamic reaction force. Strong agreements are observed between the predicted and measured responses. The model parameter values increase with an increase in grip force and vary significantly for the two tools and four postures studied. The pistol-grip tool generates larger reaction force than the right-angled tool.