Posture Control for Personal Mobility Robot using Feedback Compensation with Unstable Pole

Abstract

This paper presents a novel posture control approach using feedback compensation with an unstable pole. For the narrow and small PMR (personal mobility robot), it is required to control its posture for achieving quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the ZMP (zero moment point) cannot be settled to the desired point in the following cases: an unknown disturbance force given to the PMR, the fluctuation in the center of gravity of the PMR, and the conditioned change between the tires and the road surface. In this paper, a novel control method using feedback compensation with an unstable pole is proposed to achieve the desired ZMP at steady state. The proposed controller changes the control input for the actuator of the posture control to zero in order to achieve the desired posture angle. The effectiveness of the proposed approach is verified via experiments using a prototype of the PMR.