Shape-Morphing Wheel Design and Analysis for Step Climbing in High Speed Locomotion

The ability of wheeled mobile robots to overcome steps is often limited by wheel size. Enhancing the ability of mobile robots to overcome obstacles is essential for extending their operation area, and many previous attempts have been made by using transformable wheels, a linkage mechanism, and a spoke-type wheel-leg mechanism. In this study, we propose a shape-morphing wheel mechanism for step climbing at high speed. In the general case of low speed locomotion, a robot's wheels can be used normally. However, to overcome relatively large obstacles, the robot's wheels can extend its shape by using the proposed morphing mechanism with centrifugal force at high speed locomotion. Two modes of step climbing are analyzed that use kinetic energy conversion or impact on the steps. Detail design issues with comprehensive analyses results are presented. Results demonstrate that a robot with morphing wheels can climb a 46.67 mm obstacle at 1.82 m/s, which is 1.33 times larger than the wheel radius. We expect that this method can be applied to other locomotion modes of wheeled mobile robots.