Radioactive, chemical or biological substances are imperceptible to humans in dangerous situations and difficult to detect with remote sensing. Researchers at the Fraunhofer-Institut für Kommunikation, Informationstechnik und Ergonomie (FKIE) use specially equipped drones and robots to locate radioactive material quickly and accurately.
Radioactive material
Radioactive material and other chemical, biological, radiological, nuclear and explosive substances (CBRNE substances for short) can pose a threat to the public and emergency services. In 2023, for example, a caesium capsule only a few millimetres in size, which had fallen off a truck, led to a large-scale search operation in Australia. The recent increasing number of hybrid attacks and various destabilisation attempts have exacerbated the threat situation. Two research departments at Fraunhofer FKIE are therefore working intensively on how to use drones (unmanned aerial vehicles, UAS) and robots (unmanned ground vehicles, UGV) to best support people in these threatening situations.
Testing
The performance of such systems has been repeatedly assessed over many years at the European Robotics Hackathon (EnRicH) at the Zwentendorf nuclear power plant and at the European Land Robot Trial (ELROB). These events are both jointly organised every other year by researchers from the Cognitive Mobile Systems department. They contribute to testing drones and robots for their practical suitability under realistic operating conditions and to their further development based on the results.
Automated UAS for radioactive material detection
Commissioned by the Bundeswehr Research Institute for Protective Technologies and CBRN Protection (WIS), researchers from the Sensor Data and Information Fusion Department are developing a UAS that can quickly and accurately identify and locate radioactive material. A technology demonstrator has already been tested in field trials at the WIS site in Munster. This system can detect a radioactive source to within a few minutes to within a few metres. "The caesium capsule in Australia could only be found after days of searching with hand-held detectors. With our UAS, we could have found the radioactive capsule much faster," says Claudia Bender, research scientist at Fraunhofer FKIE, who designed the technology demonstrator together with her colleague Torsten Fiolka.
The detection process
In particular, the researchers specialise in complex data processing, sensor data fusion and automation. The detection process is highly automated and consists of a reconnaissance phase and a search phase. During the reconnaissance phase, the UAS flies over the target area and continuously collects data from the environment. Once a deviation from the background radiation is detected, the system switches to search mode.
Search mode
In this mode, the drone's flight path dynamically adapts to the information it has already collected from the environment and current sensor data. This is done using stochastic methods that estimate the probability of different positions of the source. "Once the pilot launches the drone, it initially follows a fixed flight pattern. Once sufficient sensor data is available, the system switches to adaptive search mode, where it uses the collected information to independently calculate where the source might be located," the researcher explains.
Waypoints
"In the next phase, it generates waypoints until it locates the hazardous substance and reports the exact position of the source," the researcher said. A spatial heat map shows the radiation levels over the areas scanned. A probability map can also be used to indicate the cell with the highest probability of containing the radioactive material.
Gamma detector
The drone is equipped with a gamma detector that measures radiation levels, as well as additional sensors for the detection process. These are supported by electro-optical and infrared cameras, an Intel NUC computer for data processing, an inertial measurement unit (IMU) and an LTE communication module for monitoring the data from the ground. The cameras display the live image observed by the drone. They can detect objects such as people, buildings and vehicles and display them on a map with georeferencing. The IMU records the drone's position and movement in 3D.
Follow-up project
The technology demonstrator is the result of research under the HUGIYN project (Highly Automated UAS for Detecting and Identifying y-Emitting Nuclides). In the follow-up project SLEIPNIR (Automated Airborne Detection and Identification Platform for Nuclides and Isotopes from Radioactive Sources), the researchers aim, among other things, to increase the air speed of the UAS and simultaneously locate multiple and moving nuclides.
Source: Fraunhofer
Photo: In addition to a gamma detector, the highly automated UAS also carries electro-optical and infrared cameras. (Photo: Fraunhofer FKIE)
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