作業姿勢設計支援システムにおける作業補助具装着時の作業負担評価手法の提案

摘要

We have developed a system for supporting work posture design in conformity with the requirements of the OWAS. The system succeeded in redesigning work posture and reducing workload, but has the drawback that redesigning increases work operations and consequently prolongs work time. The conceivable measures taken against the drawback are to have a system user wear a work-assisting tool and decrease workload without increasing work operations. The OWAS, however, does not assume the system user wears the work-assisting tool. Accordingly, the present study proposes a method that quantitatively measures a decrease in workload and enables the workload to be assessed in conformity with the OWAS if the system user wears the work-assisting tool. First, we define the biomechanical model of trunk flexion and estimate the lumber load. Next the subjects experiment evaluates the muscle load in erector spinae muscles. Then, the reduction in muscle load as the result of wearing the work-assisting tool is estimated. Furthermore, the result of the biomechanical model and subjects experiment leads to a formula between muscle load in erector spinae muscles and trunk flexion torque. Using the above result, we estimate the support torque given by the work-assisting tool and formulate the back posture code in the OWAS according to the biomechanical model of trunk flexion torque. In addition, the proposed method is implemented in the present system and the usefulness of the method is examined in application examples.%これまでにOWASに準拠した作業姿勢設計支援システムの開発を行っている.このシステムにより作業負担を軽減できる作業姿勢を再設計することはできたが，再設計により作業動作が増えることで作業時間が長くなるという課題があった.この対策として作業者に作業補助具を装着させ，作業動作を増やさずに作業負担を軽減することが考えられる.しかし，OWASでは作業補助具を装着した状態での評価は想定されていない.そこで本研究では，作業補助具を装着することによる負担軽減の大きさを定量的に求め，OWASに準拠した作業負担評価を可能にする手法を提案した.さらに提案手法を本システムに実装し，適用例により手法の実用性を検証した.