Much of the Earth and many surfaces of extraterrestrial bodies are composed of in-cohesive particle matter. Locomoting on granular terrain is challenging for common robotic devices, either wheeled or legged. In this work, we discover a robust alternative locomotion mechanism on granular media -- generating movement via self-vibration. To demonstrate the effectiveness of this locomotion mechanism, we develop a cube-shaped robot with an embedded vibratory motor and conduct systematic experiments on diverse granular terrains of various particle properties. We investigate how locomotion changes as a function of vibration frequency/intensity on granular terrains. Compared to hard surfaces, we find such a vibratory locomotion mechanism enables the robot to move faster, and more stable on granular surfaces, facilitated by the interaction between the body and surrounding granules. The simplicity in structural design and controls of this robotic system indicates that vibratory locomotion can be a valuable alternative way to produce robust locomotion on granular terrains. We further demonstrate that such cube-shape robots can be used as modular units for morphologically structured vibratory robots with capabilities of maneuverable forward and turning motions, showing potential practical scenarios for robotic systems.

翻译：地球表面及许多地外天体表面均由非粘性颗粒物质构成。在颗粒地形上运动对常见轮式或足式机器人装置构成挑战。本研究发现一种在颗粒介质上的稳健替代运动机制——通过自振动产生运动。为验证该运动机制的有效性，我们开发了内置振动电机的立方体形机器人，并在具有不同颗粒特性的多种颗粒地形上开展系统性实验。我们探究了在颗粒地形上运动随振动频率/强度变化的规律。相较于硬质表面，我们发现这种振动运动机制能使机器人在颗粒表面上移动更快、更稳定，这得益于机体与周围颗粒之间的相互作用。该机器人系统在结构设计和控制上的简洁性表明，振动运动可成为在颗粒地形上实现稳健运动的一种有价值的替代方式。我们进一步证明，此类立方体形机器人可作为形态结构可变的振动机器人模块单元，具备可控前进与转向运动能力，显示出机器人系统的潜在实际应用场景。