Assessment of Biomechanical Risk Factors During Lifting Tasks in a Spacesuit Using Singular Value Decomposition

Spacesuits demonstrate unique motion patterns due to their mechanical design. These motion patterns may contribute to increased musculoskeletal stresses and injury risks for the astronaut and therefore it is important to understand how suited motion patterns correlate with injury risk. This study analyzed motions from manual material handling lifting tasks performed in the Mark-III spacesuit. The motion capture data were projected onto a reposable suit model for kinematic derivation of joint angles. Singular value decomposition (SVD) was performed on the time series of the joint angles, which identified the primitive motion patterns (“eigenpostures”) across each task and their weightings as a function of time. The total joint displacement, low back moments, and postural stability were calculated as biomechanical risk metrics for each eigenposture. The eigenposture weightings were compared across tasks. Each eigenposture was associated with a different level of biomechanical stresses and some tasks, such as object pickup from the floor, had a higher composition of “risky” eigenpostures. The results of this work can be used to improve task and suit design to minimize risky movement patterns for injury mitigation.