Some aspects of high performance indoor/outdoor wheelchairs.

The last 15 years have seen electric wheelchairs evolve from slow, indoor-only devices to vehicles that are also useful for outdoor trips of several miles . But while wheelchairs with good outdoor performance are now commercially available, the evolution of the indoor/outdoor wheelchair is by no means complete . There remain important issues of safety, reliability, durability and performance which require systematic consideration of the wheelchair as a vehicle. This paper presents some of the thinking and experience of the wheelchair design project at the Biomechanics Laboratory at the University of California at Berkeley . We have been strongly influenced by the active and independent disabled community in Berkeley, and by the example of the high-performance MSE and National wheelchairs which have dramatically increased mobility for many people here. (Fig . 1 and 2 .) These influences have focused our attention on high performance indoor/outdoor wheelchairs—vehicles designed for the maximum usefulness outdoors consistent with unimpaired indoor performance. Besides the National and MSE wheelchairs, a number of other wheelchair design projects are pursuing this approach . The Veterans Administration Prosthetics Center (VAPC) has been actively interested in higher performance wheelchairs, and has designed a number of indoor/outdoor wheelchairs, among them one with an automatic variable-speed transmission (1,2,3,4) . Mobility Engineering and Development (MED) has a wheelchair with spring suspension and excellent outdoor performance, plus vertical height adjustment de-