Browsing by Author "Compton, Crystal"

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    Fit for Space: Leveraging a Novel Skin Contact Measurement Technique Toward a More Efficient Liquid Cooled Garment
    (2016-08) Compton, Crystal
    Comfort, mobility, and performance are all affected by the fit and contour of a garment to the body. Understanding the body-garment relationship allows for improvement of all of these aspects, and thus the garment and experience for the wearer. With current methods, it is possible to measure the body-garment relationship primarily in static positions, but mobile analysis is time- and equipment-intensive. A more direct garment contour and body contact monitoring procedure would benefit the functional clothing design community. Mobile measurement is especially important for functional garments, as the body-garment relationship changes over time during body movements. Here, we describe a new method developed to measure the body-garment relationship, specifically for mobile scenarios. This method detects body-garment contact using an electrical signal within a circuit formed between the garment and the body. The analog electrical connection (expressed as a varying voltage using a voltage-divider circuit) between the body and a conductive patch is processed and recorded by a microcontroller. In this investigation three main variables were evaluated for their influence on the measurement of body-garment contact: 1) patch materials, 2) applied force, and 3) patch sizes were tested within the body/garment interface. Material results showed that all of the tested materials (with the exception of one material, which contained the sparsest surface area of conductive material) facilitated a voltage response in the presence of body contact that could be viable for detecting contact between body and garment. However, preliminary tests revealed that materials with lower resistivity and more rigid structure facilitated a smoother signal with less noise, which correlated more closely with the input signal. Applied force results showed that the amount of force between the sensor and the body affects the response of the system. All patch sizes with the exception of the smallest size tested (0.3175 cm) were effective in measuring body-garment contact. The smallest diameter possible for the conductive patch is of interest, in an attempt to minimize its effect on the body-garment measuring system. A 0.635 cm diameter conductive hook fastener sensor was subsequently used to implement this method in a pilot evaluation of LCG (Liquid Cooling Garment) fit. A grid of six analog sensors (maximum amount for microcontroller used) was integrated into the right torso region of the LCG for testing. Various movements that would be similar to movements that astronauts would be performing in EVA were used to test body-garment contact. Results show distinct differences in body contact for each sensor during each movement.
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    Wearable Textile-Based Contact Sensing for Functional Fit Assessment
    (2021-08) Compton, Crystal
    Fit of a wearable system influences many human factors, including comfort, performance, and risk of injury. Sensors can provide objective and quantitative measures of mechanical interactions between the body and the wearable system for functional fit assessment. However, accurate on-body sensing is a challenge due to contaminating variables that can affect accuracy, including forces introduced by garment/body interactions such as stretching and folding. Contact sensing is a simpler sensing approach that is less susceptible to on-body contaminating variables. However, there is currently no gold-standard reference measure for on-body contact measurement. Here, multiple imperfect sources of information are compared and their respective limitations contrasted. This research focuses on evaluating methods to quantify functional fit of a wearable system by measuring contact between the body and a spacesuit component mockup during controlled robotic manikin testing through a wearable contact and force sensing e-textile garment. This study compared two sensor-based fit quantification methods (contact and force sensors) with a non-wearable reference (optical Motion Capture (MoCap)). Garment-integrated sensors were characterized in a bench test apparatus (Instron) under controlled loading conditions. The translation of these methods to the wearable environment was investigated using a robotic manikin that performs repeatable dynamic movements for a controlled on-body sensing scenario. Two different manikin conditions were evaluated to simulate effects of anthropometric differences. Under controlled conditions, contact sensors showed some hysteresis and generally exhibited higher closing forces compared to opening forces. Using the threshold calibration model, contact sensors accurately measured contacts above about 0.5 N, but recorded intermittent false negative contacts between approximately 0-0.5 N. Force sensors reliably measured contacts above 0.15 N and comparatively recorded a smaller range of false negatives between 0-0.15 N, but a much larger proportion of false positives. However, under on-body conditions, the contact-threshold calibration did not accurately translate for force sensors. There were no strong similarities found between contact sensor, force sensor, and MoCap marker data. Force sensors were difficult to calibrate and sensitive to factors like donning forces, movement, and wrinkling. Contact sensors were influenced by fewer and more resolvable contaminating variables, and were found to be better suited for on-body applications.