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What’s in it for Me? Altruism or Self Interest as the “Driver” for Inclusion
Published in Philip D. Bust, Contemporary Ergonomics 2006, 2020
John Middleton, John Mitchell, Robert Chesters
The wheelchair cushion project illustrates a slightly different approach. A local manufacturer came forward with an idea to take the companies existing seating technology into the mobility market. The original design has been developed for the aerospace, rail, automotive and military sectors to improve comfort and reduce the risk of deep vein thrombosis (DVT). The Inclusive Design manager took the company to talk with a group of wheelchair users and conduct some initial tests. This consultation exposed some of the key issues with existing wheelchair cushions (High cost and poor performance), and showed that the new prototype design had some encouraging potential. This product has moved on significantly and is entering a clinical trial stage. However what is important to remember about this project is it’s another example of self interest as a driver. The product is being developed by a company looking for financial return and significant market share; to achieve this they are developing a high volume cushion at a significantly lower price than other market leaders. Before they tool up for production the company is listening to and conducting trials with wheelchair users to ensure the design is right and clinically sound before launching into the market.
Behavior for Relieving Pressure
Published in J G Webster, Prevention of Pressure Sores, 2019
Webster (1989) proposed a monitoring/training device in which a pressure pad containing an array of 64 Interlink conductive polymer pressure sensors would be placed between the wheelchair cushion and patient to obtain a close measurement of the pressure distribution on the skin. The device would alarm whenever the pressure–duration distribution on any sensor exceeded a preset acceptable level. The safe level would be based on the pressure–duration curve developed by Reswick and Rogers (1976). This device would provide more information than previously described devices by measuring the pressure–duration distribution over a large area and would only warn the patient whenever a pressure relief was really necessary and not at fixed intervals as other simple devices did. Potential difficulties in building such a device would be choosing thin elastic compliant-enough materials for the pad, placing and maintaining calibration for pressure sensors, arranging wire connections for the compliant pad, high cost, and obtaining user compliance. Another problem would be to determine the pressure–duration curve for each individual, which presumably would vary from that of Reswick and Rogers.
Effects of simulated aging on cushion performance measured using standardized laboratory test methods
Published in Assistive Technology, 2023
Patricia Karg, David Brienza, Alexandra Delazio, Lauren Terhorst, Clair Smith
Hysteresis measures the amount of energy lost to the wheelchair cushion during a cycle of loading and unloading. Cushions with large hysteresis values may indicate a tendency to remain conformed to the user’s shape for a time after unloading, but diminished capacity to facilitate the user’s return to an erect posture after functional leaning for weight shifts or reaching. Hysteresis at 250 N and 500 N significantly decreased after both aging cycles with large effects. This may indicate more consistent support during functional leans and return to upright posture, but also increased tendency for the cushion to deform the user’s tissue due to the higher support forces. Previous studies used a prior version of the standard that employed a stepwise load-deflection test and thus could not be compared to our results using a traditional hysteresis test (Hillman et al., 2018; Hollington et al., 2014).
Validating a wheelchair in-seat activity tracker
Published in Assistive Technology, 2022
Nauman Ahad, Sharon E. Sonenblum, Mark A. Davenport, Stephen Sprigle
The WiSAT consists of three major components: a sensor mat, data logger, and mobile app. The sensor mat consists of six force-sensitive resistors produced by Tekscan (Boston, MA), which is placed on the wheelchair beneath the wheelchair cushion (Figure 1). This mat is fully inserted within the cushion cover such that the mat is beneath the cushion but above the cushion cover’s bottom surface. Once the cushion cover is zipped, the mat is secured in its position. The readings from the sensors are recorded by a data logger at a frequency of 4 Hz and are synchronized in time. The current data logger weighs 10 g, measures 5 cm in width and 7 cm in length. This data logger may be secured inside the cushion cover or in a bag attached outside of the cushion cover. This data logger is equipped with a Bluetooth module to transfer data to a mobile application. This application first calibrates the raw sensor values into force values. These values are then used to characterize weight shifts and in-seat movement. For validation, however, raw data stored on the data logger were downloaded to a computer via USB and processed using MATLAB.
The effect of cushion properties on skin temperature and humidity at the body-support interface
Published in Assistive Technology, 2018
Tzu-Wen Hsu, Shu-Yu Yang, Jung-Tai Liu, Cheng-Tang Pan, Yu-Sheng Yang
Clearly, no single cushion is ideal from all standpoints. The successful selection of an appropriate wheelchair cushion for a particular individual cannot be based on just one factor or clinical judgment. During the selection process, not only pressure distribution, but also the microclimate (heat and moisture control) between the body–seat interface should be considered. In this study, foam–fluid hybrid cushions produced the slowest rise in user skin temperatures, but the cushion material used did not significantly alter moisture accumulation.