Design and Implementation of a Two-Wheeled Inverted Pendulum Robot With a Sliding Mechanism for Off-Road Transportation

This letter proposes a multi-degrees-of-freedom two-wheeled inverted pendulum robot (mD-TWIPR) for off-road transportation. A two-wheeled inverted pendulum robot (TWIPR), popularly known as a segway, has high mobility owing to its simple structure without steering or suspension. The proposed robot has a car-like structure with a low and elongated body that provides advantages for transporting long objects, such as pipes, or transferring patients on off-road terrain. However, a car-like TWIPR structure faces several challenges, including limited acceleration, difficulty traversing slopes, asymmetric payload, and lower ability to climb steps. To address these issues, we implemented a sliding mechanism in the mD-TWIPR. The proposed mD-TWIPR is designed to move without tilting while carrying movable mass, and tilt the torso according to the 20
$^{\circ }$
slope. It can also maintain stationary on a slope with only a small wheel torque by positioning the center of mass on the fulcrum, which is advantageous for transportation operations. Furthermore, it can climb a step using a combination of the wheel and sliding mechanism. The paper discusses the modeling and design specifications and presents a prototype and experiments to verify the proposed performance of mD-TWIPR.