On the design of devices for people with tetraplegia

People with complete tetraplegia are required to work at or near their physical limits in performing daily activities. Hence, subtle improvements to the design of assistive devices can have life changing consequences. This paper establishes a new procedure for characterizing the strength of people with tetraplegia. The data obtained along with the specifications of assistive devices are implemented in the Bath Constraint Modeller and then predictions made of a subjects ability to use the assistive device. This paper shows how improvements in wheelchair propulsion ability can be made within the constraints of normal wheelchair adjustment. From the characteristic strength maps produced in this study, it is predicted that more marked improvements can be obtained by changing the position of the applied propulsion force. The study proposes a new design concept involving an offset push rim which is expected to improve wheelchair propulsion ability for people with tetraplegia. More generally, the results of this study pose new opportunities for improvements to assistive devices for people while seated.