How flying robots are revolutionizing construction

Robot arms and 3D printing portals are already found on construction sites - but mostly as heavy, permanently installed systems on the ground. In rough terrain or at great heights, they quickly reach their limits. A research team led by the Laboratory of Sustainability Robotics at Empa and EPFL has therefore investigated how flying robots could be used as autonomous construction machines in the future.

The advantage of this technology: construction drones can reach places that are inaccessible to conventional machines - whether in the mountains, on roofs, in disaster areas, or even on distant planets. They also do not require a fixed construction site, can be used in swarms, and thus offer great flexibility and scalability. At the same time, they could shorten transport routes, reduce material consumption, and make construction sites safer.

Repairs and operations under extreme conditions

Flying robots are particularly suitable for disaster operations - for example, in flooded or destroyed regions where classic vehicles can no longer get through. There, they could transport building materials and autonomously erect emergency shelters. Their use is also promising for repairs in hard-to-reach places: they could autonomously detect and repair cracks on high-rise facades or bridges without scaffolding. "The existing robot systems on the ground are often several tons heavy, require a lot of setup time, and have a limited working radius," explains Yusuf Furkan Kaya from the Laboratory of Sustainability Robotics at Empa and EPFL. Construction drones, on the other hand, are light, mobile, and flexible - but they have so far only existed at a low technical level, and industrial use is still pending.

In fact, there are already numerous prototypes demonstrating different methods of aerial construction - from the placement of individual building elements to the tensioning of cable structures to the layer-by-layer printing of building materials. At Empa, for example, flying robots have been programmed to work together in teams to print materials layer by layer for the construction or repair of structures.

Interaction of technology, material, and design

The potential of drones is disruptive - they can theoretically fly and build anywhere, provided energy supply and material transport are ensured. And they scale well: In the event of a disaster, hundreds of flying robots could immediately erect temporary infrastructures in remote areas.

At the same time, new challenges arise for future construction with drones. A central hurdle is the interdisciplinarity of the technology: The so-called aerial additive manufacturing (aerial AM) requires simultaneous advances in three areas: robotics, materials science, and architecture. Mirko Kovac, head of the Laboratory of Sustainability Robotics at Empa and EPFL, describes the interaction as follows: "A drone may be able to fly precisely, but without lightweight, load-bearing, and processable materials, it cannot reach its full potential. And even if both were available, the construction designs must be adapted to the limited precision of the flying robots to enable load-bearing structures."

Addition to existing robots

In addition to this interdisciplinary coordination, there are also technical hurdles within robotics, such as limited flight time, payload, or autonomy. The Empa study therefore presents an autonomy framework in five stages - from simple flight along a route to full independence, where flying robots can analyze the construction environment, detect errors, and even adjust the design in real-time. According to Yusuf Furkan Kaya, this is not just a theoretical model, but also a clear development plan.

However, aerial AM remains for the time being only a complementary solution to existing ground-based robot systems. This is because the energy consumption of drones is currently still eight to ten times higher, and the construction volume they can handle is limited. The researchers therefore recommend a combined approach: while conventional systems construct the lower areas of a building, drones take over from a certain height - bringing their strengths in flexibility and range to bear.