(1990-). The development of an electric wheelchair for the elderly and the disabled that can go up and down stairs is desirable. We have developed a practical, active wheelchair which can reliably ascend and descend stairs. Photo. 1 indicates the first generation model. The problem of instability during the ascent and descent of stairs was solved by the RC (remote center) mechanism indicated in Fig. 1. When the inclination of the vehicle is detected by the posture sensor, the upper chair part moves so as to become horizontal, and at the same time the center of gravity of the vehicle is always maintained in the center of the vehicle. The drive system is a mechanism which pulls a timing belt along an arc shaped rail, and drives this with a motor provided in the upper part of the wheelchair. The RC mechanism is a practical mechanism with high rigidity, and later this was also used in the TAQT Carrier.

With normal tires, it is difficult to reliably grip the stairs and go up and down while supporting its own weight with that gripper part. In the proposed active wheelchair (Photo. 1), a new system was introduced which substitutes coil springs for the tires. By doing this, it is possible to absorb shock while crossing over level differences while at the same time reliably confirming the level differences of the stairs as indicated in Photo 2. Urethane rubber nipples are provided for every 2 coil springs in this coil spring tire. These nipples configure a four segment link mechanism with the coil springs, and when attempting to produce support force in the stage differences of the stairs, the nipples are always maintained in an easy to support direction.