BRAKING ELECTRIC-POWERED WHEELCHAIRS - EFFECT OF BRAKING METHOD, SEAT-BELT, AND LEGRESTS

Objective: To examine the influence of three electric-powered wheelcha ir braking conditions and four wheelchair seating conditions on electr ic-powered wheelchair motion and Hybrid II test dummy motion. This stu dy provides quantitative information related to assessing the safety o f electric-powered wheelchair driving. Design: Rehabilitation engineer ing comparison and ANSI/ RESNA. standards testing. Convenience sample of eight different electric-powered wheelchairs. Within-chair comparis ons were conducted. Intervention: Electric-powered wheelchairs were co mpared under three braking scenarios (joystick release, joystick rever se, power-oft? and four searing conditions (seatbelt and legrests, sea tbelt and no legrests, no seatbelt but legrests, no seatbelt and no le grests), Setting: A rehabilitation engineering center. Main Outcome Me asures: The braking distance, braking time, and braking accelerations for electric-powered wheelchairs during three braking scenarios; trunk motion, head motion, and trunk angular acceleration during three brak ing scenarios and four seating conditions; and number of fails from th e wheelchairs for three braking scenarios and four seating conditions. Results: Significant differences (p <.05) were found in braking dista nce, braking time, and braking acceleration when comparing the joystic k release and joystick reverse scenarios with the power-off scenario, The mean braking distance was shortest with the power-off braking scen ario (.89m), whereas it was longest when the joystick was released (1. 66m), Significant differences (p <.05) in head displacement and trunk angular displacement were observed among braking conditions and betwee n seating conditions. There were also significant differences (p =.001 1) among braking conditions for maximum trunk angular acceleration, Th e Hybrid II test dummy fell from the wheelchairs with highest frequenc y when there were no legrests and no seatbelt used. Conclusion: The re sults of this study indicate that use of a seatbelt when driving an el ectric-powered wheelchair reduces the risk of failing from a wheelchai r, Furthermore, the use of legrests can reduce the risk of injury to t he wheelchair driver. This study shows that the most abrupt braking oc curs when deactivating the power switch. (C) 1998 by the American Cong ress of Rehabilitation Medicine and thr American Academy of Physical M edicine and Rehabilitation.