A low-cost, portable system for the assessment of the postural response of wheelchair users to perturbations.

Maintaining seated postural stability presents a serious challenge to wheelchair users in vehicles, even during normal driving conditions. The purpose of this research was to develop a system for the study of seated postural control in response to perturbations similar to those that might be experienced during vehicle turning and braking. A servo-controlled tilt platform was constructed to provide a low-cost, small, and easily transportable device for generating precise and repeatable perturbations. Tilt platform operation was examined for accuracy and reproducibility of a desired perturbation. Repeatability was high with a mean signal-to-noise ratio (SNR) of 45.4 for a given perturbation measured across 11 subjects. An initial comparison of stability results obtained on the tilt platform and in a vehicle showed a correspondence, although differences were apparent. The tilt platform has been used successfully to assess balance in spinal cord-injured subjects and to test wheelchair securement systems.