Motion-based design of elastic belts for passive assistive device using musculoskeletal model

Abstract

We are developing a passive power assist supporter called Smart Suit Lite. Smart Suit Lite is a compact and lightweight power assist device that utilizes the elastic force of elastic belts. To design the Smart Suit Lite, we developed a motion-based assist method and an extended musculoskeletal model. The motion-based assist method was used to design the arrangements and properties of the elastic belts by utilizing the relation between the target motions and the corresponding muscle forces. To analyze the assistive forces provided by the elastic belts, skin segments that represent the surface of the human body features the extended musculoskeletal model and can reproduce changes in length of the body surface with changes in posture. In this study, we used the developed method to produce the Smart Suit Lite for care workers. Furthermore, through a trial experiment, we found that wear comfort was strongly correlated with the assistance perceived the user. Thus, we have improved the Smart Suit Lite from the aspect of wear comfort, and verified the enhancement of the assistance provided by the device. In user testing, 90% of the participants reported a decrease in load on the low back during care work.