Sensors for security and protection

Modern towns require innovative infrastructure and security concepts. Once focal point at Fraunhofer FHR therefore lies on the investigation of compact and autonomous sensor applications to support the police and rescue teams.

Major events, traffic intersections, public areas – places where security is essential. When conducting research in this area, Fraunhofer FHR uses its extensive expertise in the field of high frequency and radar techniques. Radar is ideal for the contact-free detection and screening of objects.

Images generated in this manner provide the rescue teams with a comprehensive overview of the situation. For this reason, the police make increasing use of mobile sensor systems, above all when they have to protect large, complex areas (e.g. large demonstrations or folk festivals). Remote-controlled unmanned aerial vehicles (UAVs) play an increasingly important role.

The scientists at Fraunhofer FHR are currently investigating imaging radar concepts for such airborne systems. These have to be light, energy efficient and inexpensive. The first radar systems for UAVs that can carry a load of more than 5 kg have already been developed by the researchers. Images of urban terrain or disaster areas can be acquired quickly and simply using, for example, the SAR principle. In addition to using imaging techniques that have already been researched, FHR is also undergoing a technological change towards compact MIMO radar systems for 3D imaging with smaller UAVs.

Sensor applications for demanding environments

The researchers also shed light on the downside of the agile aircraft: UAVs are relatively cheap and easy to acquire. At large events, even the smallest UAV can be dangerous. Similar to a Trojan horse, they can transport hazardous material into a crown or to a selected individual unnoticed to cause damage. This potential became very clear when, for example, small drones flew over strategically sensitive areas of Paris or when a European Championship match had to be stopped due to the presence of a drone. Prevention, industrial espionage and collision prevention are issues that are also being addressed by the researchers.

The scientists are investigating different approaches – from real aperture radar and phased arrays to MIMO arrays – that allow the early detection of unauthorized aircraft in an airspace. The clever combination of physical principles and sophisticated signal processing forms the core of each and every system. In addition to making images of a scene and detecting objects, radar is also capable of recording and analyzing temporal changes, e.g. debris movements. Millimeter waves can also penetrate turbidity in the air, such as smoke or dust. It is therefore suitable for applications in locations that are difficult to access in adverse conditions, e.g. after a landslide or a traffic accident in a tunnel. Radar can create maps and situation images, which are subsequently made available to the rescue team via a mobile robot. Hence, this valuable information is available for operational planning.

The scientists have more that 55 years of experience in the area of high frequency technology and this makes Fraunhofer FHR one of the leading radar research institutes in Europe. But the scientists are well aware that multisensor concepts will be required in the future. Electronic sniffer devices and artificial eyes can record countless parameters: Are people injured? Did the fire release toxic fumes? Might the building collapse?

Solutions: functional and economic

The information that is acquired with the radar can, with the help of further sensor data, be fused to create a comprehensive overview of a situation. The researchers at Fraunhofer FHR are therefore also familiar with the strengths of other sensor systems and, together with their partners, engage in the development of systems – in particular, for autonomously operating robots – that practically cover the entire spectrum of sensor technology. Here, particular attention is paid not only to the performance of a system but also to the cost-effectiveness and efficiency of the respective system.

On the basis of silicon-germanium (SiGe), highly integrated chips can be mass produced at a low cost. In combination with the MIMO principle, it is therefore possible to realize cost-effective but efficient systems that are tailored for a specific application. In addition to having a sound understanding of the technical fundamentals, Fraunhofer FHR also has the know-how and the resources to design and construct such systems. Passive techniques such as radiometry or active high frequency sensors are used, depending on the respective application. The institute therefore brings together the full spectrum of knowledge that is required. For its customers, Fraunhofer FHR is not just a provider of services but also a capable advisor. Thanks to the expansion of SiGe competence at the institute, the development of new systems can, in future, commence with the chip design and Fraunhofer FHR will be in a position to offer its partners complete solutions from a single source.

The research activities at Fraunhofer FHR focus on the development of radar and high frequency technology-based support systems to protect emergency and rescue staff when engaging in risky activities and reduce the common risks people have to face on a day-to-day basis. These systems are used for a wide range of applications and make the hidden visible.