Development of a novel instantaneous speed observer and its application to the power-assisted wheelchair control

Nowadays, advanced power assisting tools are drawing people´s attention as emerging control application. A power-assisted wheelchair is a good example of that kind of power assisting tools. Development of controllers for a power-assisted wheelchair has just started. Though a variety of power assisting tools are being developed, there is little discussion on control methods for those tools. In this paper, we will design a controller for a power-assisted wheelchair considering necessary conditions for power assisting tools. For advanced controls of a power-assisted wheelchair, we need to control the speed of power assisting motors. However, a wheelchair runs at very slow speed and even stops frequently, which means the instantaneous speed observer is necessary for the control of a power-assisted wheelchair. From this point of view, we develop a novel instantaneous speed observer which has fast convergence speed, and apply it to a gravity compensation control of a power-assisted wheelchair. We develop a novel disturbance attenuation controller that can be generally used for power assisting tools. Proposed controller has the characteristics that the disturbance response can be modified arbitrarily. Using these observer and controller, we design a power assisting controller which can compensate gravity when a wheelchair goes on a hill.