Teams of Drones Can Print in 3D無人機組隊進行3D打印

秦珂/譯

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.

黃蜂和蜜蜂已經進化成嫻熟的飛行建筑師。為了搭建蜂巢，工蜂會按照復雜的設計規格，成群結隊地將蜂蠟、原木漿或自己的唾液堆砌在一起，最終形成的巢穴是它們的數倍大。這個過程需要花費好幾個月。這群昆蟲必須邊建造邊調整——建筑方案可能有變動；使用有缺陷的材料可能導致蜂巢變形或斷裂；建造期間工蜂可能會死亡。

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.

正是受這些昆蟲建筑團隊的啟發，帝國理工學院的機器人專家米爾科·科瓦茨開發出了一種提高3D打印靈活性的方法。以往慣用的3D打印機受噴嘴噴射范圍的限制，只能制造比自己小的物體。科瓦茨博士的團隊通過給打印機的噴嘴加裝翅膀，消除了這些限制。

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》雜志的文章中描述了一個飛行機器人系統。該系統由兩種多旋翼無人機組成：建造機和掃描機。建造機搭載3D打印噴嘴；掃描機是配有攝像頭的無人機，負責監測建造機的工作進展。

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.

建筑工作由建造機和掃描機交替進行，它們一層一層地打印和調整，直到建造完畢。首先，建造機在其作業區域上空盤旋。沿著飛行路線移動時，它開始噴射建筑材料。選材很重要——材料必須足夠輕，以便無人機攜帶，但又必須足夠結實，以支撐后續建于其上的打印層。科瓦茨博士的團隊試驗了兩種材料。一種是低密度聚氨酯泡沫塑料，這種材料在干燥時能膨脹25倍，可用作建筑物的隔熱材料。他們試驗的另一種材料是由水泥制成的混合材料，這種材料更加堅固和精密。

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.

一旦建造機噴出一層材料，掃描機就會飛過來檢查進展。然后，系統會計算出建造機接下來要建造的打印層，同時還會糾正已建成結構中可能存在的差錯。這些差錯可能是建造機造成的，也可能是建筑材料不斷堆砌產生的缺陷。在這種情況下，人們也可以介入建造過程，在必要時進行監督和糾正。

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.

研究人員用泡沫塑料建造了一個大圓柱體（共72層，高2米），又用水泥混合材料建造了一個小圓柱體（共28層，高18厘米），以此測試該系統的性能。這兩項任務并不簡單。在一圈材料上再堆一圈的做法行不通，因為難以實現完美對齊。建造機堆放波浪狀圓圈，這樣每層材料便可與上下層嵌合，從而確保最大程度的穩定性。

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.

科瓦茨博士的無人機以優異的成績通過了測試——兩個圓柱體的寬度和高度與設計方案的誤差都在5毫米以內。就英國的建筑規范而言，這是合格的。雖然已證實這些無人機具備制造能力，但科瓦茨博士說，它們一開始可能會用于維修。

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.

從理論上講，飛行機器人可以在任何地方作業，因此它們可以在充滿危險或難以進入的地方修理東西。科瓦茨博士說，他的機器人可以用來定位并密封石油或天然氣管道的泄漏點，還可以修復高層建筑隔熱層的漏洞或墻體裂縫。這些機器人可快速部署且調度成本低廉，對人類造成的風險也更小。從更長遠的角度考慮，科瓦茨博士甚至看到了他的建筑機器人未來的潛力——在月球或火星表面進行建設。

（譯者單位：鄭州大學）