Coupling mechanism of spacesuit hip joint and thigh-femur for improved maneuverability of astronauts

Abstract

The spacesuit hip joint is a crucial component that helps with astronaut maneuvering activities such as walking and kneeling. The coupling mechanism of the hip joint with the thigh-femur, and its analytical solution, is less explored in this paper, a new hip joint and its coupling mechanism are designed. For this, based on the theory of machinery, five links, which represent the joint parts and the thigh-femur, and six joints are connected to develop the coupling mechanism. A cylindrical joint is adopted to avoid impact between the hip joint and thigh-femur. Three constraints are enforced to configure the proposed coupling mechanism. A specific mechanism of four links and five joints is constructed, which not only reduces one link but also possesses the analytical solution. Equations of motion of this mechanism are derived using vectors and verified via a case study. The vector graphic method is proposed for planar rotation decomposition of the joint parts. A prototype of the new mechanism is 3D printed and tested. Experiments reveal that new mechanism can work in any body orientation. In this way, the proposed coupling mechanism and vector graphic method help improve the spacesuit hip joint. Keywords: Coupling mechanism, Motion analysis, Hard hip joint, Spacesuit