Löffler Robin, Tremmel Stephan, Hornfeck Rüdiger
Department of Mechanical Engineering and Building Services Engineering, Nuremberg Institute of Technology, Kesslerplatz 12, 90489 Nuremberg, Germany.
Engineering Design and CAD, University of Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
Biomimetics (Basel). 2023 Mar 11;8(1):117. doi: 10.3390/biomimetics8010117.
Nature provides a considerable number of good examples for simple and very efficient joint assemblies. One example is the enormously flexible cervical spine of American barn owls, which consists of 14 cervical vertebrae. Each pair of vertebrae produces a comparatively small individual movement in order to provide a large overall movement of the entire cervical spine. The biomimetic replication of such joints is difficult due to the delicate and geometric unrestricted joint shapes as well as the muscles that have to be mimicked. Using X-ray as well as micro-computed tomography images and with the utilisation of additive manufacturing, it was possible to produce the owl neck vertebrae in scaled-up form, to analyse them and then to transfer them into technically usable joint assemblies. The muscle substitution of these joints was realised by smart materials actuators in the form of shape memory alloy wire actuators. This actuator technology is outstanding for its muscle-like movement and for its high-energy density. The disadvantage of this wire actuator technology is the low rate of contraction, which means that a large length of wire has to be installed to generate adequate movement. For this reason, the actuator wires were integrated into additively manufactured carrier components to mimic biological joints. This resulted in joint designs that compensate for the disadvantages of the small contraction of the actuators by intelligently installing large wire lengths on comparatively small installation spaces, while also providing a sufficient force output. With the help of a test rig, the developed technical joint variants are examined and evaluated. This demonstrated the technical applicability of this biomimetic joints.
大自然提供了许多简单且高效的关节组件的良好范例。一个例子是美洲仓鸮极其灵活的颈椎，它由14块颈椎骨组成。每对椎骨产生相对较小的个体运动，以便为整个颈椎提供较大的整体运动。由于关节形状精细且不受几何限制，以及必须模仿的肌肉，这种关节的仿生复制很困难。利用X射线以及微型计算机断层扫描图像，并借助增材制造技术，有可能按比例放大制作出猫头鹰颈椎骨，对其进行分析，然后将其转化为技术上可用的关节组件。这些关节的肌肉替代是通过形状记忆合金丝致动器形式的智能材料致动器实现的。这种致动器技术以其类似肌肉的运动和高能量密度而出色。这种丝致动器技术的缺点是收缩率低，这意味着必须安装很长的丝才能产生足够的运动。因此，致动器丝被集成到增材制造的承载部件中，以模仿生物关节。这导致了关节设计，通过在相对较小的安装空间上智能地安装长丝来弥补致动器小收缩的缺点，同时还提供足够的力输出。借助测试装置，对开发的技术关节变体进行了检查和评估。这证明了这种仿生关节的技术适用性。
