A swarm of wasp-like 3D printing drones could be used to build in isolated areas
A team of UK-based researchers have built a swarm of drones capable of working in tandem to accurately 3D print complex concrete structures.
Considered the first example of an all-aircraft 3D printing framework, the team’s workflow sees scanning drones used to guide the extruder-mounted drones to the right place and ensure that all layers printed overlap.
Using this approach, engineers’ ‘BuilDrones’, fitted with custom printheads designed to account for aerial drift, have proven capable of autonomously creating robust tower and dome-shaped prints. With more R&D, it is believed that swarms of these robots could be deployed to build and repair infrastructure in remote areas hit by climate catastrophe, which traditional construction simply cannot reach.
A swarm inspired by nature
Considerable research continues to be devoted to the development of robots equipped with 3D printing and gantry crane systems. The idea being that if deployed on a construction site, these machines can help reduce the risk of hazardous tasks and automate others in a way that leads to potential improvements in productivity.
However, in their paper, the UK-based team highlights how these technologies currently require “scaling up of robotic hardware” to a “larger-than-desired manufacturing envelope”. According to the engineers, this large footprint makes parallel operation of other machines or people on site “difficult and dangerous”, while power capacity limitations prevent their remote operation.
To circumvent these perceived problems, engineers turned to an unlikely source of inspiration: the wasp swarm. In their natural habitat, wasps work together to deposit materials into nests in which their queen can lay eggs.
Building on this premise, the researchers have now built their own swarm, consisting of 3D printing BuilDrones as well as “ScanDrones” for guidance. In theory, the team says this “Aerial-AM” framework allows multiple robots to achieve “untethered, limitless and scalable” construction in tandem.
Make an autonomous ‘Aerial AM’
To allow their swarm to fly autonomously and in unison, the researchers programmed drones to operate in two loops. In the first, the BuildDrones are used to drop a layer, before the ScanDrones validate that it was successful and guide the next layer, facilitating a contextual drop process.
Once the team provided these drones with the necessary capabilities for real-time trajectory adaptation, material extrusion, and print monitoring, they tested them at different scales. First, the engineers experimented with 3D printing a two-meter-tall structure in quick-setting foam, a material used deliberately because of its insulation and formwork applications.
Programmed around a model predictive control scheme, the BuilDrone was found to be able to operate with sufficient accuracy to deposit material while taking various flight paths. Over a 29-minute print cycle, the device also achieved horizontal and vertical accuracies of between 0.014m and 0.006m, leading the team to move on to more advanced testing.
Using a BuilDrone with a custom nozzle, designed to process a cement-polymer composite developed specifically for construction, engineers then constructed an ultra-narrow cylindrical structure. It turned out that the robots took over two hours to complete building 28 layers, as their capacity meant they had to be refilled after each layer, but they did so while compensating for layer deviation.
As such, the researchers believe they have “successfully validated the feasibility of Aerial-AM”. That said, the UK-based engineers say their study represents a “first step in exploring the potential of aerial robots for construction”, as support materials, post-curing and task sharing by drones remain obstacles to its success.
The 3D printing industry is full of start-ups looking to disrupt the traditional construction industry with gantry-mounted concrete extrusion technologies. For example, one of the early leaders in this emerging space is COBOD, a company whose BOD2 gantry construction 3D printer has been used in various projects, such as 3D printing a house in Angola.
On a more experimental level, however, manufacturers and researchers continue to test other gantry-less approaches to building 3D printing. RepRap enthusiast Torbjørn Ludvigsen unveiled a Tower of Babel built by HangPrinter in 2017. Instead of being mounted on a gantry, the system prints with a printhead suspended from the ceiling, allowing it to overcome restrictions of building 3D printing volume.
More information about the researchers’ findings can be found in their article titled “Aerial additive manufacturing with several autonomous robots.” The study was co-authored by engineers based at Imperial College London, the University of Bath and University College London.
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The featured image shows a conceptual rendering of the 3D printing of the team’s drones in a remote location. Image via Imperial College London.