2021 Volume 39 Issue 1 Pages 78-86
We describe the development and control of an inverted-pendulum electric wheelchair that moves forward and backward and rotates according to changes in the user's center of gravity, without using hands. To rotate a conventional inverted-pendulum electric wheelchair, the user must manipulate a control handle. In the developed wheelchair, we removed the front auxiliary wheels from a conventional electric wheelchair and moved the main wheel axis to the chair's center of gravity. The wheelchair is propelled forward and backward by means of an accelerometer that monitors shifts in the user's center of gravity. Left–right rotation is controlled according to differences in air pressure between the right and left sides of an air cushion placed on the seat surface. Stable mobility that is independent of the user's weight is achieved by incorporating a robust control system that utilizes a disturbance observer. We also propose a method for preventing bias travel that achieves the same operability as running on a horizontal surface by changing the dead zone for right–left differences in air pressure.
