Stand-Alone Wearable Power Assist Suit –Development and Availability–

Abstract

The stand-alone wearable power assist suit we developed gives caregivers the extra strength they need to lift patients while avoiding back injuries. To put this suit to practical use, we improved sensing system and the mechanisms. To stabilize muscle tenseness sensing more, we developed an all-in-one sensor that built the sensor into a mesh belt and improved sensing characteristics. We expanded the movable range and function of the suit. We increased actuator output torque by increasing the number of cuffs inserted into actuators. Based on equations derived from static body mechanics using joint angles, joints torques required to maintain a position are calculated by an embedded microcomputer and required joint torques was combined with muscle sensor output signals to generate control signals. We developed an exoskeleton for measurement having the same frame and potentiometers as the suit and measured muscle force by having a user wear the exoskeleton, and proved that each unit of the suit transmitted assistance torque directly to each joint. We also found that a user wearing the suit could lift weight using half or less muscle power, i.e., muscle power doubled.