受植物根系启发,设计出能轻松插入、牢固锚定的轻量机器人锚。
Terradynamics and design of tip-extending robotic anchors
- 模仿根系尖端延伸机制,实现低插入力
- 300克设备可深插45厘米,锚固力达120牛
- 适合火星等难达环境,特别适用于小型探测任务
大多数工程桩需要远大于拔出阻力的插入力,导致需重型设备,难以在偏远或外星环境使用。而植物根系插入力仅略大于种子重量,拔出力却大得多,这得益于其尖端延伸机制。已有原型验证该机制优势,但缺乏对颗粒介质力学原理的深入理解及设计指导。本文研究了尖端延伸锚与传统桩的地面动力学差异,提出四条设计准则:(i) 延伸超过临界深度;(ii) 添加类似毛发的突起;(iii) 接近垂直延伸;(iv) 使用多个小锚而非单个大锚。基于此,开发出一款轻量化软体机器人锚,插入时反作用力小于自身重量。实验表明,300克设备可在松散火星风化层模拟物中部署至45厘米深,平均锚固力达120牛,锚固力与重量比达40:1。
原文摘要 · Abstract (English)
Most engineered pilings require substantially more force to be driven into the ground than they can resist during extraction. This requires relatively heavy equipment for insertion, which is problematic for anchoring in hard-to-access sites, including in extraterrestrial locations. In contrast, for tree roots, the external reaction force required to extract is much greater than required to insert--little more than the weight of the seed initiates insertion. This is partly due to the mechanism by which roots insert into the ground: tip extension. Proof-of-concept robotic prototypes have shown the benefits of using this mechanism, but a rigorous understanding of the underlying granular mechanics and how they inform the design of a robotic anchor is lacking. Here, we study the terradynamics of tip-extending anchors compared to traditional piling-like intruders, develop a set of design insights, and apply these to create a deployable robotic anchor. Specifically, we identify that to increase an anchor's ratio of extraction force to insertion force, it should: (i) extend beyond a critical depth; (ii) include hair-like protrusions; (iii) extend near-vertically, and (iv) incorporate multiple smaller anchors rather than a single large anchor. Synthesizing these insights, we developed a lightweight, soft robotic, root-inspired anchoring device that inserts into the ground with a reaction force less than its weight. We demonstrate that the 300 g device can deploy a series of temperature sensors 45 cm deep into loose Martian regolith simulant while anchoring with an average of 120 N, resulting in an anchoring-to-weight ratio of 40:1.
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