German researchers are developing the first prototype flying inspection robots to help document the condition of post-war buildings in Germany.

Aerial Robot Equipped to Spot Building Defects in Record Time

Nowadays unmanned aircraft are used in fields as varied as army reconnaissance missions and Amazon parcel delivery. Meanwhile, for the last three years German engineers have been investigating the use of aerial robots to carry out building inspections. Christian Eschmann, a researcher at the German Fraunhofer Institute for Non-Destructive Testing, based in Saarbrücken, is leading the project. The idea is to send a drone to check out the condition of buildings in situations where it is difficult or dangerous for human engineers to make the structural inspection. The automated aircraft is programmed to take photos, list any existing cracks, and is capable of warning of an impending disaster. The micro-aircraft the Fraunhofer team are equipping for the job – called an ‘octocopter’ as it is equipped with eight electric motors – is so far  being piloted remotely, but Christian Eschmann intends to develop technology that will enable it to work fully autonomously.

Creating a 3D model of the building

In addition to the eight electric motors which enable precise navigation, the octocopter is equipped with a high resolution digital camera that can take up to 1,200 photos during a flight lasting 15 minutes. All the images are then aggregated so as to build a 3D model of the building, compared with the current approach whereby engineers inspect concrete according to the required tests with nothing but the naked eye, marking any cracks manually on two-dimensional maps. Going forward, the Fraunhofer team are planning to develop a complete software suite, including functionality for damage recognition, image processing, plus database and documentation. In the longer term, the plan is to use a range of sensors to automate the aerial robot’s processes. The aircraft is for example already equipped with sensors that adjust for wind gusts, helping it to maintain a stable position and avoid colliding with the building. Installing navigation sensors will mean that the octocopter can actually be steered along the façades, floor by floor, from one side to the other. It will be “a bit like flying on rails,” explains Christian Eschmann.

Detecting construction faults

Eschmann is clear that “our micro-airplanes are no substitute for experts or a close-up inspection,” but he points out just how fast the machine can make its analysis. “For a 20 by 80 meter wide façade, a test engineer needs about two to three days. Our octocopter needs three to four hours for this,” he claims. The octocopter will both accelerate the inspection procedure and enable permanent monitoring of and documentation on a building from the very beginning. “Design defects and warranty claims can be identified at an early stage, so appropriate repair measures can be taken in good time. This means more security for buildings and people,” Eschmann underlines. Although drones are currently being used for the most part for military or commercial delivery purposes, initiatives such as this one show that unmanned aircraft can also help to promote urban safety and prevent accidents.


By Arthur de Villemandy