Small device for counting the number of manual wheelchair strokes

The goal of our study is to provide wheelchair users with the novel device that can easily acquire the amount of activity for prevention of metabolic syndrome. In this paper, we proposed a small device which can count the number of the wheelchair strokes when wheelchair users drive their manual wheelchair. The device counts the number of the wheelchair strokes by detecting the peak of the forward and backward acceleration signal acquired by an acceleration sensor. We defined a peak acceleration value as a high (more than 1.0m/sec²), a middle (form 0.5 m/sec² to 1.0 m/sec²), and a low acceleration (from 0.2 m/sec² to 0.5 m/sec²) and then the device counted the number of peaks by three levels of stroke intensity. The device eliminated the acceleration due to gravity, detected using 0.1 Hz low-pass filter, from the forward and backward acceleration. Moreover, we evaluated the accuracy of this device using the images measured by a small video camera when able-bodied persons drove the wheelchairs.