υ-φ-coordinate-based power-assist control of electric wheelchair for a caregiver

This paper describes the power-assist control of an electric wheelchair according to the motion mode of a caregiver. In past research work, with respect to the power-assist motion of a wheelchair, the controllers for wheelchair operators have been considered. However, caregivers are aging as well as the cared people due to the growing proportion of elderly people. This means that the power-assist control for caregivers will be strongly required in the near future. To address this issue, this paper proposes a force sensorless power-assist control for the caregiver. To detect the caregiver's input, the estimation observer of reactive acceleration is constructed in the upsilon-(phi) over dot coordinate. Then, the motion of the wheelchair is classified into straight or cornering modes by the rotational velocity calculated from the component of reactive acceleration. Furthermore, the power-assist motion control is realized on each mode by using the translational velocity calculated from the v component of reactive acceleration. This reactive-acceleration-based power-assist control in the upsilon-(phi) over dot coordinate is a novel approach in wheelchair controls. Numerical simulations and experiments are carried out to show the validity of the proposed method.