Development of a control system to determine influence of rolling resistance in manual wheelchair dynamics and mechanical efficiency
Teran Calle, Efrain Andres
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Wheelchair manufacturers design their products to provide the best possible experience to their users. The user effort and wheelchair mechanical efficiency during motion are highly affected by rolling resistance, which is a resistive force depending on many factors such as vehicle speed, tire/floor materials and tire inflation pressure. The study of this force over several conditions could lead to improvements in wheelchair design. The Anatomical Model Propulsion System (AMPS) is a robotic device to test manual wheelchairs with better repeatability than human subjects, helping to identify the effect of resistive forces. It uses electric motors to apply torque directly to the rear wheel handrims. In this thesis, a control system is developed to achieve a specified wheelchair trajectory and velocity profile, by controlling the input torque to the system. A kinetic and dynamic model is used to estimate this necessary input. Data collected from different experiments allows to determine rolling resistance under various conditions. The results show that rolling resistance also varies with acceleration, affecting the overall mechanical efficiency of a wheelchair following different velocity profiles.