Origami-based earthworm-like locomotion robots

Inspired by the morphology characteristics of the earthworms and the excellent deformability of origami structures, this research creates a novel earthworm-like locomotion robot through exploiting the origami techniques. In this innovation, appropriate actuation mechanisms are incorporated with origami ball structures into the earthworm-like robot 'body', and the earthworm's locomotion mechanism is mimicked to develop a gait generator as the robot 'centralized controller'. The origami ball, which is a periodic repetition of waterbomb units, could output significant bidirectional (axial and radial) deformations in an antagonistic way similar to the earthworm's body segment. Such bidirectional deformability can be strategically programmed by designing the number of constituent units. Experiments also indicate that the origami ball possesses two outstanding mechanical properties that are beneficial to robot development: one is the structural multistability in the axil direction that could contribute to the robot control implementation; and the other is the structural compliance in the radial direction that would increase the robot robustness and applicability. To validate the origami-based innovation, this research designs and constructs three robot segments based on different axial actuators: DC-motor, shape-memory-alloy springs, and pneumatic balloon. Performance evaluations reveal their merits and limitations, and to prove the concept, the DC-motor actuation is selected for building a six-segment robot prototype. Learning from earthworms' fundamental locomotion mechanism-retrograde peristalsis wave, seven gaits are automatically generated; controlled by which, the robot could achieve effective locomotion with qualitatively different modes and a wide range of average speeds. The outcomes of this research could lead to the development of origami locomotion robots with low fabrication costs, high customizability, light weight, good scalability, and excellent re-configurability.

受蚯蚓的形态特征以及折纸结构优异的变形能力的启发，本研究通过利用折纸技术创造了一种新型的类蚯蚓运动机器人。在这项创新中，将适当的驱动机制与折纸球结构结合到类蚯蚓机器人的“身体”中，并模仿蚯蚓的运动机制开发了一种步态发生器作为机器人的“集中控制器”。折纸球是水雷单元的周期性重复，能够以类似于蚯蚓身体节段的对抗方式输出显著的双向（轴向和径向）变形。这种双向变形能力可以通过设计组成单元的数量进行策略性编程。实验还表明，折纸球具有两种对机器人开发有益的突出力学性能：一种是轴向的结构多稳态，有助于机器人控制的实现；另一种是径向的结构柔顺性，可提高机器人的鲁棒性和适用性。为了验证基于折纸的创新，本研究基于不同的轴向驱动器（直流电机、形状记忆合金弹簧和气动气囊）设计并构建了三个机器人节段。性能评估揭示了它们的优点和局限性，为了证明这一概念，选择直流电机驱动来构建一个六节段机器人原型。借鉴蚯蚓的基本运动机制——逆行蠕动波，自动生成了七种步态；在这些步态的控制下，机器人能够以质上不同的模式和较宽范围的平均速度实现有效运动。这项研究的成果可能会促使开发出制造成本低、可定制性高、重量轻、可扩展性好以及可重构性优异的折纸运动机器人。