Cooper R A
Department of Electrical and Computer Engineering, University of California, Santa Barbara 93106.
J Rehabil Res Dev. 1989 Winter;26(1):25-32.
This paper is concerned with the directional stability of racing wheelchairs on crown roads. Three types of crown compensators are described and evaluated: the push-pull, the push-push, and the pull-pull. It was found that the push-push and the push-pull types of compensators have the most desirable characteristics, and were, in general, safer than the pull-pull type. In addition, the equations necessary to specify the minimum spring force required to compensate for the downhill turning moment, were derived and compared to the actual preset forces for the various compensators presently in use. It was found that the force required to maintain directional stability was less than that to deflect the crown compensator. This was due to the preference of athletes for additional stiffness needed for disturbance rejection, and to help compensate for any asymmetry in their stroke kinematics. It was also more cost-effective for the manufacturer to build stiffer-than-necessary crown compensators so that a range of individual and racing wheelchair combinations could use the same crown compensator.
