Vibration Measurement and Verification of Ride Comfort when a Manual Attendant-Controlled Wheelchair is Running

The tire pressure of manual attendant-controlled wheelchairs was measured in four patterns of 80 kPa, 160 kPa, 240 kPa, and 320 kPa. The number of trials for each of the four patterns of tire pressure was 10 times for a total of 40 times. The maximum power spectrum, frequency at the maximum power spectrum, and integral value were obtained from the FFT analysis data for the acceleration in three directions measured using the triaxial accelerometer, and the trends due to changes in tire pressure were evaluated. Tire pressure indicators made for this study were attached to both rear wheels of the manual attendant-controlled wheelchairs, and a dummy weight of 50 kgf was placed on the seat. Acceleration in three directions, including up/down, front/back, and left/right directions, was measured using a three-axis accelerometer attached to a heavy object. The tire pressure of the manual wheelchair for assistance was measured in four patterns of 80 kPa, 160 kPa, 240 kPa, and 320 kPa. The number of trials for each of the four patterns of tire pressure was 10 times for a total of 40 times. FFT analysis was performed using numerical analysis software for acceleration in three directions measured using a triaxial accelerometer. The maximum power spectrum, frequency at the maximum power spectrum, and integral value were obtained from the FFT-analyzed data, and the relationship with tire pressure was verified. Riding comfort was evaluated using the SD method, and the following two types of evaluation were performed: stationary and running. For both static and running conditions, the evaluation consisted of three items, including sitting comfort, sense of security, and sitting comfort of the buttocks, and four items, including the strength of shaking while running. Responses were obtained on a five-point scale from 1 to 5. Consequently, in this study, an air pressure indicator for English valves was attached to manual attendant-controlled wheelchairs, and vibration measurements were performed under controlled conditions. As a result of experiments using the manufactured vibration measuring device, it was found that the vibration tends to increase as the tire pressure rises. Furthermore, it was found that the higher the tire pressure, the worse the ride comfort.