The study of the interaction of humans with wheelchairs to improve the design

In order to evaluate a wheelchair design it is necessary to look at the capabilities of the user and the chair's intended purpose. Whilst some chairs are only required to provide infrequent mobility indoors, others need to enable the user to travel great distances out doors over rough terrain. In this respect the chair should be considered in the same manner as any other 'inclusive' product (or be useable by all). There is a need to better understand the capabilities of different users and how this affects their ability to use a wheelchair for the express purpose required. A detailed experimental investigation was carried out into the wheelchair propulsion characteristics of people with paraplegia and tetraplegia. In this investigation, subjects' posture, applied forces, and their strategies in applying forces to the wheel rims were studied. Three distinct postures and corresponding techniques were observed and subsequently modelled in a constraint-modelling environment. Here rules were developed that allowed these differing postures to be applied to a manikin representation and their effect upon the wheelchair mobility evaluated. From this study the needs for these classes of individuals were identified in order to allow the wheelchairs to be evaluated. Where conflicts existed between the chair and the user, different modifications in both chair and posture were proposed and assessed. Where no simple modifications exist such a study can provide the basis for a more radical and improved design.