Teams of Drones Can Print in 3D无人机组队进行3D打印

秦珂/译

Wasps and bees have evolved to be adept flying builders. To assemble a hive， worker insects team up to deposit wax， raw wood pulp or their own saliva to the specification of a complex design that ends up being many times their size. This process takes months. The insects must adjust as they go—building plans can change， imperfect materials can deform or break， workers can die.

黃蜂和蜜蜂已经进化成娴熟的飞行建筑师。为了搭建蜂巢，工蜂会按照复杂的设计规格，成群结队地将蜂蜡、原木浆或自己的唾液堆砌在一起，最终形成的巢穴是它们的数倍大。这个过程需要花费好几个月。这群昆虫必须边建造边调整——建筑方案可能有变动；使用有缺陷的材料可能导致蜂巢变形或断裂；建造期间工蜂可能会死亡。

It is these insect building teams that inspired Mirko Kovac， a roboticist at Imperial College London， to develop a way to improve the flexibility of 3D printing. A typical 3D printer is limited by the range of its nozzle， and can only make objects smaller than itself. Dr Kovacs team has removed these constraints by giving the printer nozzle wings.

正是受这些昆虫建筑团队的启发，帝国理工学院的机器人专家米尔科·科瓦茨开发出了一种提高3D打印灵活性的方法。以往惯用的3D打印机受喷嘴喷射范围的限制，只能制造比自己小的物体。科瓦茨博士的团队通过给打印机的喷嘴加装翅膀，消除了这些限制。

Writing in the Nature， Dr Kovac describes a system of flying robots that is composed of two types of multi-rotor drones： builders and scanners. The builders carry the 3D-printing nozzle. The scanners are robots equipped with cameras that are responsible for monitoring the progress of the builders.

科瓦茨博士在其刊于《自然》杂志的文章中描述了一个飞行机器人系统。该系统由两种多旋翼无人机组成：建造机和扫描机。建造机搭载3D打印喷嘴；扫描机是配有摄像头的无人机，负责监测建造机的工作进展。

The building process alternates between builders and scanners， layer by layer， printing and adjusting， until a structure is complete. First， a builder hovers over its area of operation and begins to release a jet of the building material as it manoeuvres along its flight path. The choice of material is import-ant—it must be lightweight enough for the drones to carry but sturdy enough to hold the subsequent layers that will be built on top. Dr Kovacs team experimented with two materials. One was a low-density polyurethane foam， which can expand up to 25 times as it dries and can be used as insulation in buildings. The other material they tested， which was sturdier and more precise， was a mixture made from cement.

建筑工作由建造机和扫描机交替进行，它们一层一层地打印和调整，直到建造完毕。首先，建造机在其作业区域上空盘旋。沿着飞行路线移动时，它开始喷射建筑材料。选材很重要——材料必须足够轻，以便无人机携带，但又必须足够结实，以支撑后续建于其上的打印层。科瓦茨博士的团队试验了两种材料。一种是低密度聚氨酯泡沫塑料，这种材料在干燥时能膨胀25倍，可用作建筑物的隔热材料。他们试验的另一种材料是由水泥制成的混合材料，这种材料更加坚固和精密。

Once the builder robot has sprayed a layer of material， the scanner robot flies over and inspects the progress. The system then computes the next layer that the builder should make， while also correcting for any errors that might have been discovered in what has already been built. These could be errors made by the builder-drones or imperfections in the expansion of the building mater-ial. At this point， people can also inter-vene in the process， supervising and correcting course where necessary.

一旦建造机喷出一层材料，扫描机就会飞过来检查进展。然后，系统会计算出建造机接下来要建造的打印层，同时还会纠正已建成结构中可能存在的差错。这些差错可能是建造机造成的，也可能是建筑材料不断堆砌产生的缺陷。在这种情况下，人们也可以介入建造过程，在必要时进行监督和纠正。

The researchers tested the systems capabilities by building both a large cylinder made of foam （72 layers and 2 metres tall） and a small cylinder made of the cement mixture （28 layers， 18 cm）. The tasks were not simple. Making circles on top of other circles would not have worked， because the perfect alignment required would have been impractical to achieve. Instead， the builder robot deposited squiggly circles that interleaved with the layers above and below， to ensure maximum stability.

研究人员用泡沫塑料建造了一个大圆柱体（共72层，高2米），又用水泥混合材料建造了一个小圆柱体（共28层，高18厘米），以此测试该系统的性能。这两项任务并不简单。在一圈材料上再堆一圈的做法行不通，因为难以实现完美对齐。建造机堆放波浪状圆圈，这样每层材料便可与上下层嵌合，从而确保最大程度的稳定性。

Dr Kovacs robots passed the test with flying colours1—the cylinders were built to within 5 mm of the width and height of the planned structures， which is up to snuff2 as far as British building codes are concerned. While these robots have been shown to be capable of manufacturing， Dr Kovac says their bread and butter3 will probably be， initially， in repair.

科瓦茨博士的无人机以优异的成绩通过了测试——两个圆柱体的宽度和高度与设计方案的误差都在5毫米以内。就英国的建筑规范而言，这是合格的。虽然已证实这些无人机具备制造能力，但科瓦茨博士说，它们一开始可能会用于维修。

Because the flying robots can， in theory， operate anywhere， they could fix things in dangerous or otherwise in-accessible places. Dr Kovac says that his robots could be used to spot and seal leaks in oil or gas pipelines， repair leaky insulation or fix cracks on tall buildings. These robots could be deployed more quickly， cheaply and with less risk to humans. Thinking more long term， Dr Kovac even sees a potential future for his construction robots， building on the surfaces of the Moon or Mars.

從理论上讲，飞行机器人可以在任何地方作业，因此它们可以在充满危险或难以进入的地方修理东西。科瓦茨博士说，他的机器人可以用来定位并密封石油或天然气管道的泄漏点，还可以修复高层建筑隔热层的漏洞或墙体裂缝。这些机器人可快速部署且调度成本低廉，对人类造成的风险也更小。从更长远的角度考虑，科瓦茨博士甚至看到了他的建筑机器人未来的潜力——在月球或火星表面进行建设。

（译者单位：郑州大学）