Development of wheelchair that can acsend and descend unknown height step by using disturbance observer

Abstract

Although wheelchair is useful as hardware for moving purposes such as the elderly and disability person, it is not suitable for driving in environments other than flat ground such as steps and ditches, and so there is a problem that the range of activities is limited. In this paper, we propose an add-on type step elevating mechanism and its control method that realizes step movement without the need for human visual inspection or intervention of operation in wheelchair elevating operation. The basic configuration of the mechanism consists of two arm rotation mechanisms whose drive source is a linear actuator and auxiliary drive wheels. By cooperative controlling these devices, it is possible to move the step by the chair occupant alone and while maintaining the horizontal posture. Applying a disturbance observer, this paper suggests a method that can estimate the step height without the need for a dedicated sensor even when a wheelchair user encounters the step for the first time. As a result of implementing this step detection method, it is shown that a step of up to 175 mm can be detected without relying on human eyes and its height can be estimated within the tolerance without using a dedicated sensor. In addition, it was confirmed that wheelchair with an adult man actually boarded can ascend and descend step height of 140 mm, as a result of implementing an arm movement model that realizes step up and down while maintaining the posture of the wheelchair body horizontally for the arm mechanism after touchdown.

Keywords

• wheelchair
• disturbance observer
• traveling stairs by personal vehicle
• height estimation without sensor
• welfare technology