ADJUSTABLE WHEELCHAIR OBSTACLE SIMULATOR AND INSTRUMENTATION FOR ASSESSING WHEELCHAIR SUSPENSION
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Wheelchair users are exposed to whole-body vibrations, particularly when traversing rugged terrain such as in less resourced areas. Suspension systems have been added to wheelchair systems to protect occupants from secondary injuries associated with whole-body vibration. Current suspension systems need to be further developed in order to optimize the protection against these secondary injuries. Until further research finds conclusive evidence for comfort level, and the onset of injury due to vibrations, it has been recommended to reduce whole-body vibration exposure to the lowest possible level. A versatile testing apparatus and method were designed and built to detect the acceleration and frequencies a wheelchair occupant would be exposed to while riding on simulated rough terrain. A novel dummy was instrumented with accelerometers to measure the accelerations and frequencies experienced by the wheelchair user. The apparatus and method was able to detect peak acceleration magnitudes, and was able to detect resonant frequencies and their intensities with either a PSD or FFT analysis. The minimum observable effect of change between two test conditions ranged from 6.0% for peak acceleration analysis when using six tests and a light dummy; to 41.0% for PSD analysis when using three tests and a heavy dummy. This adjustable testing apparatus and method can be used to tune a wheelchair system suspension design because it can elucidate whether or not a design is able to reduce accelerations and attenuate resonant frequencies experienced by a wheelchair occupant.