Structural Analysis And Optimization Of Joint System Of The Lower Limb Of Spacesuit

According to the planning of China’s manned space mission,China will carry out planetary detection in the future,which raises higher requirements on the performance of existing spacesuits,especially the flexibility and comfort of the joints of lower limb system.The current research lacks the analysis of the performance of human’s lower limb joint which in the spacesuit,the optimization of the joint structure and the theoretical analysis of the walking process of human gait in lower gravity environment.In this paper,the structural analysis and optimization design of the corrugated hip joint and the flat pleated knee joint of the space suit are carried out.The gait walking process of the spacesuit lower limb system in earth and lower gravity environment is simulated,and the changes of drag torque of lower limb joint during walking are analyzed.A finite element model of corrugated hip joint considering human contact,cavity pressure change and restraint layer structure was established,and the experimental verification was carried out.The simulation results of drag torque of joint in the unmanned condition is verified by experiment.The drag torque of spacesuit joint with human body in it or not was compared and analyzed.The main source of the drag torque of joint is analyzed.The parametric model of the corrugated hip joint is established.The influencing factors of the drag torque of joint are studied.Based on the proxy model,the corrugated joint structure is optimized and the best structural parameters are obtained..A finite element model of a flat pleated knee joint composed of three layers of overlapping pleats was established.The model considers the factors which include the human contact and the change of cavity pressure,and compares the drag torque of joint in the manned and unmanned states.The characteristics of the drag torque of flat pleated joint are analyzed,and the sources of the resistance torque of joint are analyzed.A parametric model of the flat pleated knee joint was established,and the optimal pleated structure was obtained by direct optimization.The human lower limb model and the spacesuit lower limb system model were established,and the coupled simulation analysis with human body and clothes was carried out.The walking process of human body’s gait was simulated in three gravity environments of Earth,Mars and Moon,and three joints of the were obtained.The curve of drag torque of three joints which include hip,knee and ankle in the walking process of gait is obtained.And the composition of the drag torque of lower limb joints was analyzed from two aspects which include human body motion and contact between human and clothing.In this paper,the drag torque curves of the corrugated joint and the flat pleated joint in the manned and unmanned states are obtained,then the causes of the drag torque of two joints are revealed,and the optimal structural form for the lower limb joint design of the spacesuit is gived.This paper presents a simulation method for walking process of human gait in lower gravity environment,and proposes a theoretical calculation method for drag torque of joint during astronaut motion in lower gravity environment,which can help to analyze the drag torque of joint in the lower limb system of spacesuit.In summary,the study of lower limb system of spacesuit in this paper has certain theoretical significance and engineering reference value.