超磁歪素子を用いた車いす駆動能力計測システムの開発

抄録

Wheelchair fittings are principally made on the basis of users' measurements and on the basis of the experience and knowledge of persons such as rehabilitation engineers at local rehabilitation centers. However, to choose a proper wheelchair among the diversity of options available, a quantitative evaluation of the propelling force of each particular wheelchair would be useful. Such evaluation systems have been developed, but for laboratory use only. Our study aims to establish a prototype of ambulatory propelling force measurement system which is built directly in the hub of one of the wheelchair wheels. In our previous research, measurement systems using magnetostrictive torque sensors had been described, but the excessive width and weight of such devices affected the results. To overcome this problem, a measurement system using a giant magnetostrictive material was developed. The excess width of the wheel is merely 25 mm and excess weight of the wheel is merely 1.7 kg. This system enabled us to measure the propelling force and speed of each wheelchair accurately. We also developed a mechanism to attach the measurement unit to the wheels of different diameters. Experiments were performed with units attached to 20- or 24-inch-diameter dedicated wheels. The results show that such a system is able to assess the propelling force, speed and left-right coordination both for adults and children.