1 - 5 of 5
-
PublicationAn adaptive sensing approach for the detection of small UAV: First investigation of static sensor network and moving sensor platform( 2018)Fusion of information in heterogeneous multi-modal sensor networks has been proven to enhance sensing capabilities of ground troops to detect and track small unmanned aerial vehicles flying at low altitude. Nevertheless, the area coverage of a static sensor network could be permanently or temporally impacted by geographic topologies or moving obstacles which could reduce the local sensing probabilities. An additional moving sensor platform can be used to temporarily enhance sensing capabilities. First theoretical analysis and experimental field trials are presented using a static sensor network consisting of acoustical antenna array, a stationary FMCW RADAR and a passive/active optical sensor unit. Additionally, a measurement vehicle was applied, equipped with passive/active optical sensing devices. While the sensor network was used to monitor a stationary area with a sensor dependent sensing coverage, the measurement vehicle was used to obtain additional information outside the sensing range of the network or behind obstacles. A fusion of these data sets can provide an increased situational awareness. Limitations and improvements of this approach are discussed.
-
PublicationSorting of black plastics using statistical pattern recognition on terahertz frequency domain data( 2016)The sorting of used plastics is an ever-growing market field which is further pushed by new EU regulations in, e.g., car recycling. Modern recycling techniques require pure or almost pure fractions of polymers. These pure fractions can be generated from waste using modern sorting technologies based on specific mechanical, electrical and chemical material properties such as density, conductivity and melting point. The thermal recycling of plastics is no longer seasonable. More modern recycling techniques require pure fractions containing only a single variety of polymer. A large portion of the plastic waste contains black or multilayer materials that are not sortable with todays' sorting technologies. To overcome this challenge, three Fraunhofer institutes are working together to develop a new type of sorting system. As a first step, we have developed a frequency domain line-scan camera working in the terahertz range with frequencies below 300 GHz. Since the entropy in terahertz signals below 300 GHz is not as high as needed for simple classification, more complex statistical pattern recognition methods are needed. The application of those methods to the problem of sorting black plastics as the second step in this joint project is presented in this paper. These methods have to be integrated into a real sorting system, which is the third part of our joint project. The modular approach gives the ability to integrate our sensors and algorithms into existing sorting systems.
-
PublicationShunting yard management using millimeter wave radar( 2011)Management of shunting yards is a highly responsible task and mainly done manually with visual inspection or at modern stations done with a highly sophisticated sensor technology. A few distributed radar sensors allow the permanent inspection of the rails and wagons under all weather conditions. The new concept is described and illustrated by measurement results.
-
PublicationBuilding damage assessment in decimeter resolution SAR imagery: A future perspective( 2011)Damage assessment after natural disasters (e.g. earthquakes) is crucial for initiating effective post disaster relief actions. Synthetic aperture radar (SAR) sensors are an important source of information since they can map the extended areas quickly, in an uncensored manner, and independent from the weather conditions and the solar illumination. The spaceborne SAR sensors TerraSAR-X and COSMO-SkyMed reach spatial resolutions of about 1 meter and permit to analyze urban areas at the level of individual buildings. With this type of data completely destroyed buildings can be detected, while different types of damages can not be distinguished. In this paper we analize a set of decimeter resolution SAR data from an experimental airborne SAR system acquired from an artificial village of different types of destroyed buildings. We show that the increased resolution supports a more reliable identification of destroyed buildings, and allows the classification of destroyed buildings into several basic damage classes. Furthermore, we discuss some initial ideas for the development of novel automatic building damage assessment methods and give an outlook on how this type of data can be efficiently used in damage assessment scenarios.
-
PublicationISAR imaging of helicopters using millimeter wave radars( 2009)
