Evaluating Lumbar Shape Deformation With Fabric Strain Sensors

Abstract

Objective To better study human motion inside the space suit and suit-related contact, a multifactor statistical model was developed to predict torso body shape changes and lumbar motion during suited movement by using fabric strain sensors that are placed on the body. Background Physical interactions within pressurized space suits can pose an injury risk for astronauts during extravehicular activity (EVA). In particular, poor suit fit can result in an injury due to reduced performance capabilities and excessive body contact within the suit during movement. A wearable solution is needed to measure body motion inside the space suit. Methods An array of flexible strain sensors was attached to the body of 12 male study participants. The participants performed specific static lumbar postures while 3D body scans and sensor measurements were collected. A model was created to predict the body shape as a function of sensor signal and the accuracy was evaluated using holdout cross-validation. Results Predictions from the torso shape model had an average root mean square error (RMSE) of 2.02 cm. Subtle soft tissue deformations such as skin folding and bulges were accurately replicated in the shape prediction. Differences in posture type did not affect the prediction error. Conclusion This method provides a useful tool for suited testing and the information gained will drive the development of injury countermeasures and improve suit fit assessments. Application In addition to space suit design applications, this technique can provide a lightweight and wearable system to perform ergonomic evaluations in field assessments.

Preliminary Validity and Acceptability of Motion Tape for Measuring Low Back Movement: Mixed Methods Study

“…Multiple IMUs are needed to evaluate spine posture and movement, which can become burdensome to the wearer [39]. Recently, flexible or fabric-based devices using piezoresistive sensors or other types of strain sensors have been used to address some of these prior limitations [37,40,41]. Table 1 includes a summary of existing sensor types for measuring low back posture and movement, characteristics that are measured, and benefits and limitations.…”

Seamless Weft Knit Vest with Integrated Needle Sensing Zone for Monitoring Shoulder Movement: A First Methodological Study

“…To prevent the strain range of human activity from exceeding the effective strain range of the sensor zone, it is necessary to avoid pre-stretching of the sensor zone by wearing commercial garments. This further hinders the benefits of universal and seamless manufacturing of commercial garments, which impacts mass production and applications for multiple body types [ 40 , 41 , 42 , 43 , 44 , 45 ]. Therefore, achieving a balance between good sensor performance and the full formability of commercial garments has become a challenging issue in the development of textile-based sensors.…”