Mode switching control for a personal mobility robot based on initial value compensation

Abstract

The present paper introduces a novel standing-up control strategy using Initial Value Compensation (IVC) for a Personal Mobility Robot (PMR). Personal mobility robots, which are wheeled inverted pendulum type mobility-assist devices, have the advantages of a small turn radius, maintaining a level seating posture on a slope, and a small footprint as compared to conventional electric wheelchairs with four wheels. On the other hand, the user must maintain the posture of the PMR by the use of additional assist wheels on the ground when mounting/dismounting and working from the PMR. In order to achieve these requirements, we propose the following approach. First, the PMR accelerates to lift its assist wheels off the ground and detects whether the assist wheels are in contact with the ground. The feedback controller is then switched to wheeled inverted pendulum mode using the proposed IVC. The proposed IVC is designed to improve the transient responses and suppress the amplitude of the control input and the jerk component for reducing the shock to the driver. The effectiveness of the proposed approach has been verified by numerical simulations and experiments using a prototype PMR.