Snake-like robots can achieve flexible movement by simultaneously actuating multiple joints; however, the challenge of high power consumption by driving numerous servomotors under high-load conditions remains. To address this issue, we propose a mechanism that transforms the rear link of a snake-like robot into a wheel-like configuration, enabling a three-wheeled vehicle mode that provides the same traveling speed and efficiency as a wheeled mobile robots on flat surfaces. First, we detail the method for driving the servomotor to achieve undulating locomotion in the snake-like robot with nonuniform link lengths. Next, we propose a method for smoothly switching between the complex-shaped wheel mode and undulating locomotion. Finally, we conduct experiments to assess the travel efficiency in both the undulating mode and the proposed wheel mode across various road surface conditions. Our results demonstrate that the wheel mode achieves higher travel efficiency than the undulating mode on the smooth floors and asphalt.

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