Self‐Sustained Snapping Drives Autonomous Dancing and Motion in Free‐Standing Wavy Rings

Harnessing snapping, an instability phenomenon observed in nature (e.g., Venus flytraps), for autonomy has attracted growing interest in autonomous soft robots. However, achieving self‐sustained snapping and snapping‐driven autonomous motions in soft robots remains largely unexplored. Here, harnessing bistable, ribbon ring‐like structures for realizing self‐sustained snapping in a library of soft liquid‐crystal elastomer wavy rings under constant thermal and photothermal actuation are reported. The self‐sustained snapping induces continuous ring flipping that drives autonomous dancing or crawling motions on the ground and underwater. The 3D, free‐standing wavy rings employ either a highly symmetric or symmetry‐broken twisted shape with tunable geometric asymmetries. It is found that the former favors periodic self‐dancing motion in place due to isotropic friction, while the latter shows a directional crawling motion along the predefined axis of symmetry during fabrication due to asymmetric friction. It shows that the crawling speed can be tuned by the geometric asymmetries with a peak speed achieved at the highest geometric asymmetry. Lastly, it is shown that the autonomous crawling ring can also adapt its body shape to pass through a confined space that is over 30% narrower than its body size.

利用在自然界中观察到的一种不稳定现象——捕捉（例如捕蝇草）来实现自主性，在自主软机器人领域引起了越来越多的关注。然而，在软机器人中实现自持捕捉以及由捕捉驱动的自主运动在很大程度上仍未得到探索。在此，报道了利用双稳态带状环形结构，在恒定热驱动和光热驱动下，在一个软液晶弹性体波状环库中实现自持捕捉。自持捕捉引发连续的环翻转，从而驱动在地面和水下的自主舞动或爬行运动。这些三维独立波状环采用具有可调几何不对称性的高度对称或对称破缺的扭曲形状。研究发现，由于各向同性摩擦，前者有利于原地周期性的自主舞动；而由于不对称摩擦，后者在制造过程中沿着预先定义的对称轴呈现定向爬行运动。研究表明，爬行速度可通过几何不对称性进行调节，在最高几何不对称性时达到峰值速度。最后，研究表明自主爬行环还能调整自身形状以通过比其身体尺寸窄30%以上的受限空间。