デジタルヒューマンモデルを用いた身体負担評価に基づく製品の最適設計法

Abstract

Physical workload reduction is one of the significant factors in product design. This study proposed a simulation based ergonomic design method with digital human modeling (DHM) to accomplish the efficient ergonomic product design. DHM simulation was applied to evaluate the joint moment ratios (JMRs), and the product design for physical workload reduction was formulated as the minimization of the average and maximum JMRs to determine the optimal solution. The proposed method was applied to a problem of designing the forward distance of handrail to support the sit-to-stand (STS) movement. The STS motion, exerted force on the handrail, and subjective perceived workload were measured with nine subjects. The STS motions and exerted force of DHMs were predicted from the measured data, and physical workload simulation was performed with multiple DHMs so as to reflect the anthropometric diversity. The response surfaces of the average and maximum JMRs were predicted as functions of the forward distance, and Pareto frontiers of each DHM condition were determined. We found that there was no trade-off between the average and maximum JMRs and the optimal forward distance was in the 345−400 mm range. The optimal forward distance agreed with the result of subjective perceived workload. Therefore, we concluded that the proposed method obtained the reasonable optimal solution.