When objects are packed in a cluster, physical interactions are unavoidable. Such interactions emerge because of the objects geometric features; some of these features promote entanglement, while others create repulsion. When entanglement occurs, the cluster exhibits a global, complex behaviour, which arises from the stochastic interactions between objects. We hereby refer to such a cluster as an entangled granular metamaterial. We investigate the geometrical features of the objects which make up the cluster, henceforth referred to as grains, that maximise entanglement. We hypothesise that a cluster composed from grains with high propensity to tangle, will also show propensity to interact with a second cluster of tangled objects. To demonstrate this, we use the entangled granular metamaterials to perform complex robotic picking tasks, where conventional grippers struggle. We employ an electromagnet to attract the metamaterial (ferromagnetic) and drop it onto a second cluster of objects (targets, non-ferromagnetic). When the electromagnet is re-activated, the entanglement ensures that both the metamaterial and the targets are picked, with varying degrees of physical engagement that strongly depend on geometric features. Interestingly, although the metamaterials structural arrangement is random, it creates repeatable and consistent interactions with a second tangled media, enabling robust picking of the latter.

翻译：当物体聚集堆放时，物理相互作用不可避免。此类相互作用源于物体的几何特征：某些特征促进纠缠，而另一些则产生排斥。当纠缠发生时，集群展现出由物体间随机相互作用引发的全局复杂行为。我们将此类集群称为纠缠颗粒超材料。我们研究了构成集群（以下称为颗粒）的物体的几何特征，以最大化纠缠效应。我们假设，由高纠缠倾向颗粒组成的集群，亦会表现出与另一纠缠物体集群相互作用的倾向。为验证此点，我们利用纠缠颗粒超材料执行复杂机器人抓取任务——此类任务中传统夹持器往往难以胜任。我们采用电磁铁吸附超材料（铁磁性）并将其投放到另一物体集群（目标物，非铁磁性）上。当电磁铁再次激活时，纠缠作用确保超材料与目标物被同时抓取，其物理啮合程度高度依赖于几何特征。值得注意的是，尽管超材料的结构排布具有随机性，其与第二纠缠介质却能产生可重复且一致的相互作用，从而实现对后者的稳健抓取。