Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, United States of America.
Bioinspir Biomim. 2022 Oct 11;17(6). doi: 10.1088/1748-3190/ac8710.
Crabs are adept at traversing natural terrains that are challenging for mobile robots. Curved dactyls are a characteristic feature that engage terrain in order to resist wave forces in surf zones. Inward gripping motions at the onset of the stance could increase stability. Here, we add inward gripping motions to the foot trajectories of walking gaits to determine the energetic costs and speed for our 12 degree of freedom (DOF) crab-like robot, Sebastian. Specifically, we compared two gaits in which the step size (stance length) was the same, but the swing trajectories were either triangular (to minimize trajectory length) or quadrilateral (in which the leg deliberately oversteps in order to perform a distributed inward grip). The resulting gripping quadrilateral gait significantly outperformed the nongripping triangular gait on diverse terrains (hard linoleum, soft mats, and underwater sand), providing between 15% and 34% energy savings. Using this gait eliminates the advantage of spherical end effectors for slip reduction on hard linoleum, which may lead to a better understanding of how to use crab-like morphology for more efficient locomotion. Finally, we subjected the walking robot to lab-generated waves with a wave height approximately 166% of the dactyl length. Both gaits enabled the robot to walk undisturbed by the waves. Taken together, these results suggest that impact trajectory will be key for future amphibious robots. Future work can provide a deeper understanding of the relationships between dactyls, gaits, and substrates in biology and robots.
螃蟹擅长在移动机器人难以穿越的自然地形中穿行。弯曲的指节是其特征之一，用于在冲浪区抵抗波浪力。在起始姿势时进行向内夹持运动可以增加稳定性。在这里，我们将向内夹持运动添加到螃蟹机器人 Sebastian 的行走步态的足迹中，以确定其 12 自由度（DOF）的能量成本和速度。具体来说，我们比较了两种步态，它们的步幅（步长）相同，但摆动轨迹分别是三角形（以最小化轨迹长度）或四边形（腿故意超越以进行分布式向内夹持）。结果表明，具有夹持功能的四边形步态在各种地形（硬油毡、软垫和水下沙）上的表现明显优于非夹持的三角形步态，节省了 15%到 34%的能量。这种步态的使用消除了球形末端执行器在硬油毡上减少滑动的优势，这可能有助于更好地理解如何利用螃蟹形态进行更高效的运动。最后，我们让步行机器人在实验室产生的波浪中行走，波浪高度约为指节长度的 166%。两种步态都使机器人能够不受波浪干扰地行走。综上所述，这些结果表明，冲击轨迹将是未来两栖机器人的关键。未来的工作可以更深入地了解生物学和机器人中的指节、步态和底物之间的关系。
