Department of Mechanical & Aerospace Engineering, Case Western Reserve University, Cleveland, United States of America.
Department of Computer Science, Case Western Reserve University, Cleveland, United States of America.
Bioinspir Biomim. 2021 Mar 1;16(2). doi: 10.1088/1748-3190/abdd94.
Sandy beaches are areas that challenge robots of all sizes, especially smaller scale robots. Sand can hinder locomotion and waves apply hydrodynamic forces which can displace, reorient, or even invert the robot. Crab-like legs and gaits are well suited for this environment and could be used as inspiration for an improved design of robots operating in this terrain. Tapered, curved feet (similar to crab dactyl shape) paired with a distributed inward gripping method are hypothesized to enable better anchoring in sand to resist hydrodynamic forces. This work demonstrates that crab-like legs can withstand vertical forces that are larger than the body weight (e.g. in submerged sand, the force required to lift the robot can be up to 138% of the robot weight). Such legs help the robot hold its place against hydrodynamic forces imparted by waves (e.g. compared to displacement of 42.7 mm with the original feet, crab-like feet reduced displacement to 1.6 mm in lab wave tests). These feet are compatible with walking on sandy and rocky terrain (tested at three speeds: slow, medium, and fast), albeit at reduced speeds from traditional feet. This work shows potential for future robots to utilize tapered and curved feet to traverse challenging surf zone terrain where biological crabs thrive.
沙滩是对各种大小的机器人，尤其是小型机器人具有挑战性的区域。沙子会阻碍机器人的移动，波浪会产生水动力，从而使机器人移动、翻转。类似螃蟹的腿和步态非常适合这种环境，并且可以为在这种地形中运行的机器人的改进设计提供灵感。假设带有分布式向内夹持方法的锥形、弯曲的脚（类似于螃蟹的跗节形状）能够更好地在沙子中锚固以抵抗水动力。这项工作表明，类似螃蟹的腿可以承受大于体重的垂直力（例如，在水下的沙子中，提起机器人所需的力可能高达机器人重量的 138%）。这样的腿有助于机器人在波浪施加的水动力作用下保持原位（例如，与原始脚部的 42.7mm 位移相比，螃蟹状脚部将实验室波浪测试中的位移减少到 1.6mm）。这些脚可以在沙质和岩石地形上行走（在三种速度下进行测试：慢、中、快），尽管速度比传统的脚慢。这项工作表明，未来的机器人有可能利用锥形和弯曲的脚来穿越充满挑战的冲浪区地形，而这些地形是生物螃蟹的栖息地。
