Birds’ nests inspire and stimulate the imagination. Architects have indeed already successfully imitated their design, as shown by the example of the National Stadium in Beijing, but not the methodology of nest building. Can drones imitate how birds build, and later repair, their nests?
Image: Yusuf Furlan Kaya, Imperial College London and Empa
Mirko Kovač has seized on this idea and never let go. Kovač is a professor at Imperial College in London and Head of the Laboratory of Sustainability Robotics at Empa in Dübendorf. He enthusiastically presents his group’s rooms at Empa: gymnastics mats on the floor, a wind turbine’s rotor blade, bridge elements and tunnel tubes, surrounded by a lattice. What looks like a large playground at first glance is actually a flight arena for drones. It is hoped that one day, these will inspect infrastructural elements such as bridges, industrial chimneys and tunnels, detect damage and even repair it right away using 3D printing.
The story began in 2016 at Imperial College in London. Mirko Kovač, who had studied mechanical engineering at ETH Zurich and obtained his doctorate in robotics at EPFL, joined forces with scientists from the fields of architecture, computer science and materials science to make this vision a reality. “From the very beginning,” he is keen to emphasise, “multidisciplinarity was a central aspect.” In the years that followed, the team succeeded in producing a cylindrical concrete structure with 27 layers by means of additive manufacturing, i.e. 3D printing. The approach they took uses a drone measuring one metre in diameter, weighing several kilograms and able to carry a tank containing almost half its own weight in concrete. The liquid concrete is pressed out of the drone with great force and deposited in layers on the object to be built. The main difficulties are the changing environmental conditions outdoors and the inherent imprecision of the flying printers. This is countered by means of a second drone, a scanning drone: This measures the built part and the progress made, giving constant feedback to the printer drone and thus optimising the construction process. Such pairs of drones can be used to construct complex and fragile structures at great heights, as well as to repair objects such as wind turbines, which are risky for workers to access.
For one further development, Mirko Kovač was again inspired by nature. Or to be more precise: by ants, collectively building a nest. He envisaged a swarm of drones working together to make a structure using 3D printing. The advantages are obvious: optimised flight paths, higher construction output per battery charge and lower building materials consumption. For the concept to work though, a drone must be able to print at any location on the object being built. Like ants, it must have a standard set of possible actions that enable it to keep building without knowing the big picture. Feasibility has been successfully proven and a platform has been created that can be used in a variety of ways. In the future, it is conceivable that actual robot ecosystems will be used in construction, encompassing not only drones but also conventional robots and 3D printers – not in order to replace humans, but to relieve them in dangerous locations. As Mirko Kovač repeatedly points out: “Drones that are like artificial life forms aid sustainability in construction, and will make the world a better and safer place in the long term.”
Who knows? Maybe Mirko Kovač’s drones will soon be building in inhospitable places like Antarctica or on Mars? Corresponding projects are in the starting blocks.
Comprehensive and further information on the subject can be found in the article 3D printing of concrete structural elements.