B8-3　Estimation of Optimal Handrail Position for Elderly based on Digital Human Modeling Simulation

抄録

The sit-to-stand (STS) movement becomes difficult with aging. Providing handrails is one method of making the STS movement easy. However, an experimental physical workload evaluation requires a number of trials, and it evokes accumulated fatigue of subjects. Therefore, an approximate optimal handrail position should be predicted before the experiment with elderly subjects. The objective of this study was to estimate the optimal handrail position for elderly by minimizing the physical load of the STS movement calculated with the digital human modeling (DHM) simulation. The joint angles during the STS motion and the exerted force on the handrail were measured for nine young adult subjects with varying the forward distance of handrail from the edge of chair seat. The forward distances were 150, 250, 350, 450, and 550 mm. The STS motions and exerted force of DHMs were determined from the measured data. The joint moment ratio (JMR) is considered as the indicator of physical workload, which is obtained by dividing the joint moment by its maximum joint moment. The reduction ratios of maximum joint moments for elderly against young adult were determined based on a statistical data, and they were reflected to DHM simulation to estimate the physical workload for elderly. The response surfaces of the maximum JMRs were predicted as functions of the forward distance, and optimal forward distance was determined. The simulation results showed that the higher stature had the larger maximum JMR. The optimal forward distance increased with the increase in the stature of DHM, and it was in the range of 380−430 mm.