Simulation design of flexible Unpowerd lower limb exoskeleton

Abstract

Unpowered lower limb exoskeletons has the advantages of light weight, low metabolic cost, rarely change normal gait, no external source, sustainable work, etc. It is gradually becoming a hot topic in exoskeleton robot research field. Conventional unpowered lower limb exoskeleton pay less attention to gait energy efficiency, a novel unpowered lower limb exoskeleton is proposed. Firstly, the motion characteristics of lower limbs are analyzed; the joints moment and the position of heel are obtained. Next, the structure design for flexible unpowerd lower limb exoskeleton with rubber energy storage element is developed, and the mechanism of crouch gait was analyzed. Then the musculoskeletal model with exoskeleton is established, and the joint moment for the crouch person improve obviously, which contain elastic energy storage elements with different stiffness coefficient. The joint moment for the right leg is about 33N/mm during terminal stance (heel off) or preswing (toe off), but it in the left leg appears atrough, the value is about 20N/mm. Moreover, the variable ranges of the elongation of elastic elements for the ankle is bigger than hip during walking. The results of this study can provide a theoretical basis for the optimal design of unpowered lower extremity exoskeleton.