Design and Verification of an Active Lower Limb Exoskeleton for Micro-low Gravity Simulation Training

Abstract

Exploring the most economic method to achieve micro-low gravity simulation training has been troubling researchers for a long time. Hence, this paper presents an active lower limb exoskeleton to counteract gravity of astronauts with a very low cost compared to conventional ways. It includes two link rods, fixing modules, servo motors used in hip and ankle, which is designed as common structures of lower limb exoskeletons. Note that selected servo motors can feed back driving torque and rotating angle at the same time, which makes exoskeleton more integrated and light. Different from common control methods applied in assistive exoskeleton to help wearers walk or run, zero-force control is used in the exoskeleton to counteract gravity for micro-low gravity simulation training of astronauts. Healthy volunteers are recruited to wear this exoskeleton and their surface electromyography (sEMG) signals are recorded during the process. Experimental results show that the proposed lower limb exoskeleton can averagely counteract gravity of more than 60% for each subject in static and dynamic states.