An Analyses of Power Wheelchair Safety While Driving (Crash Study)

Principal Investigator/s: Rory A. Cooper, PhD

Co-Investigator/s: Michael Dvorznak, BS, Thomas Corfman, MS, Songfeng Guo, PhD

Analyses of Power Wheelchair Safety While Driving (Crash Study)

An article was published in the December issue of the Archives of Physical Medicine and Rehabilitation entitled “Tips and Falls During Electric-Powered Wheelchair Driving: Effects of Seatbelt Use, Legrests, and Driving Speed.” The objective of this study was to measure the response of a 50th percentile Hybrid II anthropometric test dummy (ATD) while riding in an electric-powered wheelchair (EPW) over common obstacles to determine whether optimal wheelchair fit, use of seatbelts, and driving speed affect the frequency and severity of ATD tips and falls. The ATD was driven in 4 different EPWs over a door threshold, curb cut, 5 ramp, and 50-mm curb at speeds of 1 and 2m/s, with and without the use of a seatbelt, and at varying legrest heights. The response of the ATD was observed and recorded as no fall, loss of control (the ATD falls forward or sideways but remains in the EPW), the ATD falls out of the EPW, or the EPW tips completely. A total of 97 adverse events out of 1700 trials were recorded: 88 were losses of control and 9 were ATD falls. No complete tips of any EPWs were recorded. Statistical analysis showed a relationship between the adverse events and use of seatbelts, legrest condition, and obstacle, however, there was no relationship between adverse events and speed and no obstacle was designated to be the most problematic.

Other work has been submitted to the Journal of Rehabilitation Research and Development. The study “Kinematic Analysis for Determining Bioequivalence of a Modified Hybrid III Test Dummy and a Wheelchair User” investigates whether a Hybrid III test dummy (HTD) can be modified to produce a motion response similar to the response of a wheelchair user with a spinal cord injury. The HTD and a wheelchair test pilot (TP) were seated in an EPW. The EPW was driven at 0.8, 1.4, 2.0 m/s and 3 braking conditions were used to slow the EPW to a stop. The motion of the HTD and TP were recorded and kinematic measures such as trunk angular displacement, velocity, and acceleration were calculated to determine bioequivalence (BE). BE analyses, commonly used in the pharmaceutical industry to show that a generic drug is as effective as the name brand, were used to test if the kinematic measures were similar. The BE method used produced differing results. The HTD and TP demonstrated population and individual bioequivalence, indicating that the HTD is a suitable surrogate for a wheelchair user in low speed dynamic studies. However, the HTD and TP were not average bioequivalent.

This study was part of the University of Pittsburgh Center for Injury Research Control