Verification Tests of a Lightweight Assist Suit for Assistance of Lifting Motion and Its Evaluation Based on Lumbar Load Model for Holding Heavy Object with Half-Sitting Posture

Abstract

In this study, the power assist suit which has two McKibben type pneumatic artificial muscles filled with low-pressure air on the back side of a full harness type safety belt (passive-type assist suit) was extended so that it can enhance the assist ability to lift heavy objects by providing a compressed air to the artificial muscles (active-type assist suit). In addition, the lumbar load model was derived to evaluate the assist suit for holding a heavy object with half-sitting posture. First, the labor-saving effect of the passive-type assist suit for lifting and taking down the heavy object was verified through the oxygen consumption via analysis of expired gas and muscle activity calculated from surface electromyogram. Second, improvement of the assist effect of the active-type assist suit compared with the passive-type assist suit for lifting and taking down the heavy object was verified through muscle activity. Third, decrease of the lumbar disc load by wearing the passive-type assist suit was verified through static analysis based on the derived lumbar load model and evaluation experiments of holding the heavy object with half-sitting posture.