Quantifying Forward Tipping Characteristics of a Front Wheel Drive Electric Powered Wheelchair

Benjamin A. Salatin, B.S.1,2 , Hongwu Wang, M.S.1,2 , Garret G. Grindle, M.S.1,2 , Rory A. Cooper, Ph.D.1,2
1 Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, Pittsburgh, PA
2 Departments of Rehabilitation Science and Technology, University of Pittsburgh


In the United States today, there is an estimated 300,000 electric powered wheelchairs (EPW) in use. In 2003 over 100,000 wheelchair related accidents were treated in United States emergency departments with 65-80 percent of the accidents being tips and falls. The objective of this study was to quantitatively characterize the forward roll rate (ωy) about the lateral (Y) axis of a front wheel drive EPW to determine if the roll rate can be detected at various linear speeds when stopping suddenly on a downward slope. The Smart Controller developed by the Human Engineering Research Laboratories was used on a front wheel drive EPW. The experiment consisted of driving the EPW down a 1:7 sloped test ramp and doing an emergency stop about half way down the ramp. The stopping test was carried out at three different speeds, 2 m/s (4.5 mph), 1.5 m/s (3.6 mph), and 1 m/s (2.2 mph). The roll rate followed a very predictable and similar pattern in all three tests. Average data values and standard deviations for the variables, peak roll rate, time to peak, and stop time at each speed setting were analyzed. The peak roll rate increased linearly from the slowest speed to the fasted speed exactly as expected. However, the time to peak roll and time to stop variables did not exhibit the same linear progression possibly due to some inconsistencies in some of the trial data used. The data collected showed that there was a definite correlation between the roll rate and forward velocity when the EPW decelerated suddenly.


Electric powered wheelchair, Tips and Falls, Safety, Control algorithm


The work is supported in part by Quality of Life Technology Engineering Research Center, National Science Foundation (EEC-0540865), the National Institutes of Health (1R03HD048465-01A1), and the VA Rehabilitation Research and Development Service (B3142C).

Author Contact Information:

Benjamin A. Salatin, Human Engineering Research Laboratories, VA Pittsburgh Healthcare System, 7180 Highland Drive, Bldg 4, 151R1-H, Pittsburgh, PA 15206, Office Phone (412) 365-4850 EMAIL: salatinb@herlpitt.org