Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH, United States of America.
Bioinspir Biomim. 2018 Jan 19;13(2):026003. doi: 10.1088/1748-3190/aaa342.
Earthworms locomote using traveling waves of segment contraction and expansion, which when symmetric result in straight-line locomotion and when biased result in turning. The mechanics of the soft body permit a large range of possible body shapes which both comply with the environment and contribute to directed locomotion. Inspired by earthworms, our new platform Compliant Modular Mesh Worm robot with Steering (CMMWorm-S) has been developed to study this type of locomotion. Compared with our previous robots, CMMWorm-S is capable of an entirely new movement (turning) using two actuated degrees of freedom per segment (a total of 12 motors). The modularity of the mesh, composed of 3D printed rigid pieces and flexible tubes, allows for the interchange of components to vary the stiffness of the robot. On this robotic platform, we show that locomotion efficiency is sensitive to body stiffness. In particular, greater bending stiffness improves turning locomotion, whereas greater circumferential stiffness speeds straight-line locomotion. The data presented demonstrate the contribution of each component towards the longitudinal, circumferential and bending stiffness of mesh-based robots. These analyses can help in the development of design criteria useful for future soft robotic peristaltic devices.
蚯蚓通过节段的收缩和扩张来移动，当收缩和扩张对称时，会导致直线运动，而当收缩和扩张偏斜时，会导致转向。柔软的身体结构使得蚯蚓能够采用多种可能的身体形状，这些形状既符合环境，又有助于定向运动。受蚯蚓的启发，我们开发了一种新的可变形模块网格蠕虫机器人转向（Compliant Modular Mesh Worm robot with Steering，CMMWorm-S）平台，用于研究这种运动方式。与我们之前的机器人相比，CMMWorm-S 每个节段有两个可驱动自由度（总共 12 个电机），能够实现全新的运动（转向）。网格的模块化由 3D 打印的刚性部件和柔性管组成，允许组件的互换以改变机器人的刚度。在这个机器人平台上，我们展示了运动效率对身体刚度的敏感性。具体来说，更大的弯曲刚度可以改善转向运动，而更大的周向刚度可以提高直线运动速度。所呈现的数据证明了每个组件对基于网格的机器人的纵向、周向和弯曲刚度的贡献。这些分析有助于为未来的软机器人蠕动装置开发有用的设计标准。
