Unidentified items of luggage and other suspicious object are frequently found at airports, stations and other public areas. The security services must always assume that they contain a bomb. This problem recently became an object of research at Fraunhofer FHR.

Examining a suspicious vest for explosives.
© Bundeswehr/Bienert

Examining a suspicious vest for explosives.

Examining a suspicious suitcase with the remote-controlled manipulator PackBot®.
© Landeskriminalamt Nordrhein-Westfalen

Examining a suspicious suitcase with the remote-controlled manipulator PackBot®.

The joint research project »USBV Inspector« aims to support emergency personnel in the deployment area. This involves aspects such as the reconnaissance of suspected improvised explosive devices (IEDs) with a radar sensor as well as crime scene measurement and evidence preservation with 3D environment monitoring and a HDR optics system for forensic purposes.

In this project, which is funded by the Federal Ministry of Education and Research within the framework of the »Research for Civil Safety 2012 -2017« program, Fraunhofer FHR, together with Bureau of Criminal Investigation in North-Rhine Westphalia, the Leibnitz University in Hanover, ELP GmbH and Hentschel GmbH as well as the Federal Bureau of Criminal Investigation and the Federal Police Force as associated partners, is developing a multimodal sensor suite which combines the aspects and support possibilities described above. This sensor suite is mounted on a remote-controlled robot and brought into the vicinity of the suspected IED. Within a short period of time it will be possible to determine whether the suspicious object is really a bomb or merely an item of luggage that has been forgotten. The joint research project »USBV Inspector« will run until the end of 2017 and is coordinated by Fraunhofer FHR. The radar sensor required for fast reconnaissance is also being researched and developed within the institute.

Technological basis and research

The technological basis of the imaging techniques at Fraunhofer FHR takes the form of a millimeter wave radar with a very high bandwidth which allows an enormously high depth resolution. The utilization of this radar in conjunction with the synthetic aperture radar (SAR) technique paves the way for the high-resolution radar imaging of all objects. Due to the good material penetration characteristics, the system can look inside the container and carry out three-dimensional measurements of the contents. This radar imaging system therefore facilitates the rapid identification of an IED on the basis of the spatial characteristics and the local form of the object in the container.

Apart from the research work on the sensor, the scientists are also looking into ways of determining the optimal SAR trajectories for the measurement of the object: this depends on the shape of the respective object, its position in the environment and the position of the robot, whereby the data from the 3D environment monitoring is used to determine these conditions. The next step involves an evaluation as to how these conditions can be used to find the best possible ratio between the measurement speed and resolution so as to minimize the reconnaissance time. The shape and environment of the object therefore determine the possible form of the SAR trajectories and data acquisition as well as image reconstruction are adapted accordingly.

The arm of the robot used for the SAR imaging exhibits proper motion during the measurement, and hence, this form of proper motion must be measured with an inertial sensor with time stamps and taken into account in the computation of the high-resolution images. Even small position deviations not accounted for in the measurements can lead to blurring effects in the image which, of course, compromise the identification. This can be avoided by compensating for the proper motion.


In addition to the technical innovations created at Fraunhofer FHR in the field of radar imaging and the research areas of the other partners, the multimodal sensor suite opens up a full range of new innovations for the rescue personnel when operating in the deployment area. Forensic aspects, for example, are becoming increasingly important when it comes to improving the evidence against the perpetrators. The multimodal sensor suite offers a corresponding basis here with the three-dimensional measurement of the crime scene to secure optical evidence. Moreover, when carrying out reconnaissance without x-ray technology, the emergency personnel is – thanks to the research and development of radar imaging – no longer directly exposed to the danger of an explosion.