Driverless excavator excavates the foundations
The worker in the cabin has been replaced by a box of computers and sensors. Based on a 3D model of the building, the robot independently excavates the foundations highly accurately.
It’s another noisy construction site, with excavators, cement mixers, and power tools pounding out their noise. A roof is mounted on one house while foundations are excavated on an adjacent site. In a third house plasterboard is being installed onto timber framing. But there are no human beings here. All the tasks – from the casting of foundations to the installation of the last roof tiles – are being carried out by robots, while drones are flying about to check the progress.
This is how a construction site might soon be able to operate. Small computers, artificial intelligence and new sensors are enabling robots to build an entire house, from erecting the walls to installing the roof, within a single day.
Robots have already proved that they can build houses almost without human assistance, as in Switzerland, where the robotconstructed DFAB House opened in February 2019. Robots have also been selected, appropriately, to build a new robot museum in Seoul which opens in 2022. But beyond special cases, these developments will make houses easier to build, and that is becoming vital. According to the UN, by 2030 new homes will be required for some three billion people – 40% of the world’s population.
Not only can the new robotic building crews handle physical construction tasks, they are also on their way to taking over the roles of architects and building managers by designing, planning and supervising the entire construction process.
Automatic arms paint cars
Robots have been used in factories for decades, of course. In the car industry, robotic arms have welded and painted car bodies since the 1970s. Unlike people, robotic arms can repeat the same motions and tasks around the clock, maintaining accuracy without getting tired or injured. Robots can carry out monotonous jobs that include many repetitive tasks, and can do so more efficiently than humans.
But a factory is a predictable place. There is a standard process, from individual parts entering the system until the completed product appears at the other end. In such a setting it is relatively simple to design a robot to pick things up from a belt conveyor and put them in a box over and over again.
A construction site is a far more complex environment: machines and building materials can end
up in unexpected places; construction schedules can change; delays or weather conditions can require that workers switch to jobs other than those planned. Flexibility in cooperation and the value of traditional skills are among the reasons that the construction business is still dominated by human workers.
Lasers for ‘eyes’
In recent years, new technologies have made robots much more flexible and increasingly autonomous. One crucial technology is the increasing power of small embedded computers, those which are integrated in a machine and customised to carry out specific jobs, unlike an ordinary computer which functions independently, not embedded. Embedded computers are used widely, examples being those in traffic lights and the navigation equipment of planes. Today, these computers are powerful enough to solve calculation-intense tasks such as ongoing image analysis that
robots can use to distinguish between the many different tools and materials used on a construction site.
At the same time as the development of embedded computers, sensors have become more accurate. They are used in conjunction with LiDAR technology, using lasers to allow robots to create a detailed 3D map of their surroundings. Laser light is emitted, and the sensors measure distances and shapes based on reflections and the speed of reflectiion from the surroundings. LiDAR is already used in driver-less cars, and it will make robots better at navigating the changing environment of a building site.
Drones provide the plan
New technological breakthroughs mean that robots could go further, taking over the entire construction process.
The Komatsu company in Japan has automated the process of measuring, excavation and levelling the site for a house. According to the company, it previously took up to three days for human land surveyors to make an altitude map of an area covering 20,000m , but drones and real-time kinematic positioning (RTK) can draw up an accurate 3D map of the area in about 30 minutes. RTK improves the accuracy of an ordinary GPS signal by comparing GPS coordinates with a signal from an antenna on the construction site. This can correct any small deviations from GPS satellites which are located thousands of kilometres away and so improve GPS accuracy from a few metres down to a few centimetres. A drone equipped with a 20-megapixel camera takes one photo per second, combining them with GPS coordinates so that a computer can subsequently make a 3D map which is transmitted to Komatsu’s autonomous machines, including data on where and how much soil is to be removed. Armed with this information a bulldozer and excavator begin to remove soil completely independently.
3D printer builds a house in a day
Once the soil has been levelled, there’s still the challenge of building walls. For this job, engineers throughout the world are turning to a method normally used for rather smaller things: 3D printing.
These 3D printers for houses use an additive process by which layers are printed on top of other layers to form the walls of the house. An American company, Contour Crafting, has developed a printer
with a printhead that moves in all d i rections – length, width, and height – via a rail system. Quick-drying concrete flows from the nozzle on the head. In time even exterior treatments and electrical installations could be be printed using the same process. According to Contour Crafting, a house of some 180m which might take six months to construct conventionally can be printed in 24 hours.
Robot is a quick bricklayer
3D printers spray material from nozzles, but there are also robots that imitate a bricklayer’s job, placing bricks on top of each other in an accurate pattern.
The SAM100 robot consists of an arm that takes bricks from a belt conveyor, adds mortar, and lays the bricks on the wall. A column on either side of the field of activity emits laser light that functions as the bricklayer’s string line when the robot places the bricks. The robotic arm motions are controlled by algorithms that match the arm’s speed and angle in proportion to the line. According to Construction Robotics, which is responsible for SAM100, the robot can remove 80% of the physical lifting work for a human bricklayer while making them three to five times more efficient, because they need only install the robot, feed it bricks and mortar, and adjust the joints. SAM100 can lay up to 3000 bricks a day compared with 500 for a human bricklayer.
Map renewed every three seconds
Other robots are ready to carry out carpentry work inside the house. Japanese scientists have programmed the HRP-5P humanoid robot to collect plasterboard sheets and install them using electric power tools.
The robot is equipped with motors and flexible joints allowing its body to rotate in wider angles and to carry more weight than people. The robot moves about the construction site by means of LiDAR technology.
Every three seconds the robot emits a shower of laser light which hits objects in the room, updating a detailed 3D map consisting of the points from which the light is reflected. Then when HRP-5P lifts a plasterboard sheet in front of its head, blocking the head’s camera and sensors, it can still navigate correctly because it holds the latest 3D model of its surroundings in its memory, and continues to update it.
Before the installation of a plasterboard sheet, the robot must choose the right gear, and for this purpose it uses algorithms with artificial intelligence – neural networks inspired by the human brain – to recognise and differentiate between electric screwdriver, drilling machine and hammer.
Robot-built house has opened
The new generation of computer-controlled workers has already proved that they can take over almost the entire construction process. The DFAB House in Switzerland opened in early 2019. Its load-carrying walls were made by a computer taking metal threads and welding them together into a wall-shaped grid, which was then filled with concrete. The second floor rests on a large concrete plate that was ‘printed’ by a 3D printer. The roof-carrying woodwork that sits on the concrete plate was sawn, drilled in and assembled by robotic arms.
The next step for the robots may be to take over the task of installing electricity and water pipes, and indeed contractors have already begun to use robots in these fields. Building Information Modelling (BIM) technology allows robots to handle these sensitive installations. BIM provides computer-generated 3D models of houses, from the walls and roof to the location of pipes and cables. These models are constantly amended during the course of the construction so they can be used to finetune the motions of the robots.
Mars base to be built by robots
If the future of automated building seems assured, such robots can do more than just solve the problem of housing shortages by more quickly building houses. This could be key to the colonisation of the Solar System, especially in adverse environments such as Mars, where the thin atmosphere subjects astronauts to harmful space radiation. They will need a protective base, but for every kilogram of payload in a space rocket, nine times as much fuel is required. With existing
technology it simply isn’t possible to send astronauts to Mars with all required machinery and building materials. But it may be possible to send robots which could build a base for astronauts to use later.
NASA is cooperating with AI SpaceFactory in the development of 3D printers which could build a base on Mars. The base is to be printed with a material made of basalt, which exists on Mars, mixed with bioplastic that could be extracted from plants grown on the planet. The resulting material would protect against cosmic radiation and insulate against the extreme temperatures on Mars.
A grand vision of the future might see robots handling construction work on moons, planets and asteroids throughout the Solar System, so that humans can arrive to populate fully constructed bases in which to live, work, and carry out research.