Quantitative Evaluation of Changes in Joystick Operation Induced by Downhill Turning Prevention Control for a Power Wheelchair

Abstract

Downhill turning of a wheelchair on a cross slope is one of the risk factors in driving. To prevent this unintended change of a track by the gravity, downhill turning prevention control (DTPC) has been developed and widely used for power wheelchairs. However the effectiveness of DTPC has not been quantitatively evaluated. In this study, we investigated DTPC-induced changes in joystick operation and wheelchair behavior by test drives on a cross slope. The results of data logging during the test drives, where ten users of a power wheelchair participated, successfully demonstrated the effects of DTPC. The offset operation of joystick to turn uphill on the cross slope was decreased by DTPC, providing an evidence that the burden of manual control was reduced. The evaluation measure related to wheelchair veering was also significantly decreased. These results quantitatively indicate that DTPC improves driving stability of a power wheelchair and thus its safety on a cross slope.