Power-assist on slope with velocity compensation for attendant-propelled electric wheelchairs

Up to now, numerous electric-powered wheelchairs (EPWs) have been developed for the disabled and the elderly. Among these EPWs, the traditional attendant-propelled power-assist wheelchairs (APAWs) usually run at a preset speed and greatly reduce the attendant's burden. Since the attendant's operating feeling is essential for the widespread use of the APAWs, many control approaches have been studied and developed. In the power-assist of our developed APAW, the speed of the wheelchair is controlled by the attendant's force to keep an appropriate burden with a natural operational feeling. In this study, we clarify the fact that the handle velocity of the APAW inevitably changes when passing through a slope, which causes the attendant to have an uncomfortable feeling. This phenomenon and its result in the uncomfortable feeling have not been reported yet. Consequently, in order to reduce or eliminate such uncomfortable feelings, we construct an APAW model on the slope and propose a velocity compensation method. From simulations and experiments, the validity of the proposed velocity compensation control is verified.