Estimation Model of Joystick Input Changes Induced by a Downhill Turning Prevention Control Mounted on a Powered Manual Wheelchair

In order to improve safety of powered wheelchairs running on cross sloped surfaces, we have developed a downhill turning prevention control (DTPC) system. The effect of DTPC on wheelchair maneuvering has been quantified and evaluated by an evaluation experiment, where six wheelchair users participated. In this study we characterized in detail DTPC-induced changes of the evaluation measures in order to construct a quantitative criterion for screening target users of DTPC. As a result, we found that DTPC-induced improvement in the total scores of the evaluation measures positively correlated with the total scores without DTPC. The multiple regression analysis revealed that the evaluation measures derived from the wheelchair behavior without DTPC are secondary factors on the evaluation score improvement in addition to those from the joystick input. The measures without DTPC are likely to negatively correlate with the controlling skills of the drivers. These results of the statistical analyses, therefore, suggest that the benefit from DTPC will be larger as controlling skill of the users is worse.