Modeling Torso Shape and Assessing Lumbar Kinematics with Flexible Strain Sensors

Astronauts that are exposed to long-term microgravity and perform functional tasks in a spacesuit are at high risk for low back pain and injury. To understand and mitigate injury risks, it is necessary to evaluate the lumbar kinematics. This evaluation can be achieved using fabric-based strain sensors. Therefore, the purpose of this study was to develop and test a method to assess the torso shape deformation and lumbar motion with fabric-based strain sensors that were adhered on the body. Twelve male study participants performed lumbar articulation postures while 3D body scans and sensor measurements were collected. A multilayer principal component and regression-based model was constructed to estimate torso shape and lumbar kinematics. The model demonstrated good lumbar kinematics estimation (< 15°), fairly accurate torso (RMSE < 4.5 cm), and lumbar (RMSE < 1.2 cm) geometry estimation. This method may become a useful tool for measuring suited lumbar motion.