Control of a longitudinally extended two-wheeled inverted pendulum robot with a sliding mechanism

Abstract This paper proposes a balance control strategy for the longitudinally extended two-wheeled inverted pendulum robot (LE-TWIPR), which integrates wheel control with a sliding mechanism. By compensating for continuous center of mass shifts caused by disturbances and unbalanced payloads, the proposed method achieves stable control even under continuous external force conditions. The controller combines model predictive control with a disturbance observer that estimates external forces acting on the system in real time. Distance sensors mounted at the front and rear of the robot are used to estimate the slope angle, enabling collision avoidance on inclined surfaces. Based on the estimated external force and slope angle, slider compensation references are generated to maintain dynamic stability. Experimental results demonstrate that the LE-TWIPR can maintain balance and travel at a maximum speed of 1.5m/s under unbalanced payload conditions, and successfully traverse an $8^\circ$ slope. These findings validate the effectiveness and real-time capability of the proposed control approach.