Starting and stopping kinetics of a rear mounted power assist for manual wheelchairs.

A rear mounted, powered, drive wheel has been developed to assist with mobility for manual wheelchairs. The version tested operates in two modes (indoor and outdoor). To start in the indoor mode users must initiate propulsion with sufficient force to trigger the motor. To stop users must apply a braking force through the handrims. . The objectives of this study were to compare (1) the minimum force required to start a wheelchair with and without the drive, and (2) the distances and forces needed to stop a wheelchair at different treadmill speeds with and without the device. We used a crossover study design with 24 able-bodied persons. The main outcome measures were starting force single push speed, stopping distance, and stopping force. Participants did not have significantly increased starting force or single push speed using the drive. Participants had significantly shorter absolute stopping distance (p = 0.045 and reduced stopping force (p = 0.02) using the add-on at both treadmill speeds. Given the decreased stopping distances, the add-on may be a viable option for wheelchair users with limited upper limb strength.