Posture stabilization for a personal mobility robot using feedback compensation with an unstable pole

The present paper introduces a novel posture control approach using feedback compensation with an unstable pole. A narrow and small personal mobility robot (PMR) requires control of its posture in order to achieve quick turning and high acceleration. However, in the conventional control approach that uses the posture angle as a controlled variable, the zero moment point (ZMP) cannot be set to the desired point if an unknown disturbance force acts on the PMR, if the center of gravity of the PMR fluctuates, or if the conditions between the tires and the road surface change. In the present paper, a novel control method using feedback compensation with an unstable pole is proposed in order to achieve the desired ZMP at the 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 experimentally using a prototype PMR.