Tweel (TM) technology tires for wheelchairs and instrumentation for measuring everyday wheeled mobility
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This thesis is focused on two aspects related to wheeled mobility: 1) Evaluating the impact of a new tire design on powered mobility, and 2) Instrumentation that permits better monitoring and assessment of wheeled mobility in everyday use. The Tweel technology tires developed by Michelin USA are comprised of an outer polyurethane ring supported by polyurethane fins instead of metal spokes, which allow the tire to deflect under pressure. As a wheelchair tire they offer a potential breakthrough as they have deflection properties similar to a pneumatic tire while maintaining the low maintenance of a solid foam-core tire. A study was conducted to compare the Tweel technology tires to standard solid foam-core tires for vibration transmission, traction and overall life span. The Tweel technology tires failed produce any significant difference in vibration transmitted to the user compared to solid foam-core tires. Additionally, the Tweel technology tires showed significant signs of deterioration after a month long field trial, thus indicating a short life span. However, Tweel technology tires provided better traction on both dry and wet concrete. Overall, Tweel technology tires have to be re-engineered to provide better damping properties, leading to lower vibrational levels transmitted to the user. The second section this thesis addressed the need to develop a methodology of measuring mobility in everyday usage. This section is part of a greater ongoing research project at CATEA (Center for Assistive Technology and Environmental Access) aimed at understanding everyday wheelchair usage. Methodology was developed to measure bouts of mobility that characterize wheelchair usage; which includes the number of starts, stops, turns and distance traveled through the day. Three different technologies which included, Accelerometer unit on the rim of the drive wheel, Gyro-Accelerometer unit on the frame of the chair and Reed switches, were tested. Testing included various criteria for accuracy, durability and compatibility for measuring bouts of everyday wheeled mobility. Although a single technology could not be used to measure all aspects of mobility, the Accelerometer unit on the rim met the design criteria for measuring starts stops and distance, while the Gyro-Accelerometer unit met the requirements for measuring turns.