Electromagnetic induction sensors work by sending out magnetic fields and detecting the response from the electric currents generated when the field interacts with a metallic target.
While simple versions of these sensors are capable of detecting most land mines, advanced sensors are required to tell the difference between a land mine and harmless buried metal objects, which can include bottle tops, nails, shrapnel and spent bullets.
“We built this facility to aid in the development of advanced electromagnetic induction sensors and associated detection algorithms, mainly because little was known about how the signals collected by these sensors from land mines changed when the mines were buried underground at odd angles,” said Waymond Scott, a professor in Georgia Tech’s School of Electrical and Computer Engineering.
Scott and Gregg Larson, a senior research engineer in Georgia Tech’s George W. Woodruff School of Mechanical Engineering, constructed the facility with funding from the U.S. Army and described it at the recent SPIE Defense, Security and Sensing Symposium.
The testing structure was built with five computer-controlled axes – three translational stages and two rotational stages – and one manual axis. During testing, an individual sensor or array of sensors is fixed in the middle of the measurement region while the rotational stages orient a target and move it along a prescribed path around the sensor.
For testing, the researchers place the sensor in the center of the area so that it is located as far as possible from any surrounding metal, including the floor that contains structural steel and the aluminum beams of the positioner frame. In the procedure used to measure individual targets, they also controlled for the response from the surrounding metal structures.
The system can collect measurements of typical targets, including shell casings, wire loops, ball bearings and land mines. The data from each target is plotted as response curves, which are a function of the metal content and structure of the target and help discriminate a land mine from other metal buried in the ground. Previous field tests have shown that the shape of the response curves did not change when targets were buried at different depths, but the researchers wanted to know if the same was true for targets buried at different angles.
“This facility allows us to collect measurements of typical targets and clutter objects with respect to location and orientation, which would be very difficult to measure in the field due to the difficulty of accurately placing and rotating the target,” said Scott.
At the symposium, the researchers presented data collected in the facility from three targets – a single wire loop, a composite target with three wire loops and a 9 millimeter shell casing. Their results with the single wire loop and shell casing showed that the shape of the response curve was the same for all of the rotation angles, but the amplitude of the response changed with rotation angle. The more complex three-loop target exhibited changes in the shape and amplitude of the curve when the rotation angle was modified.
The researchers plan to use these results to make improvements to the sensor hardware and processing algorithms. Future efforts in the experimental facility will focus on measuring more targets and investigating methods for summarizing the massive amounts of collected data into simple physical models. The researchers also plan to improve the processing algorithms to help characterize more complicated targets and refine the detection and discrimination methods for electromagnetic induction sensors.
Experiments conducted in the facility will ultimately help researchers better discriminate between land mines and harmless metal objects, which will lead to reduced false alarm rates.
“This facility will help us develop advanced electromagnetic induction sensors that are most effective and able to quickly, accurately and repetitively measure the response of a buried target,” noted Scott.
This work is supported in part by the U.S. Army Night Vision and Electronic Sensors Directorate, Science and Technology Division, Countermine Branch and in part by the U. S. Army Research Office under Contract Number W911NF-05-1-0257. The views and conclusions contained in this document are those of the researchers and should not be interpreted as representing the official policies, either expressed or implied, of the Army Research Office or the U.S. Government.
Technical Contact: Waymond Scott (404-894-3048); E-mail: (email@example.com)
Abby Vogel | Newswise Science News
Electromagnetic water cloak eliminates drag and wake
12.12.2017 | Duke University
Two holograms in one surface
12.12.2017 | California Institute of Technology
MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.
Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...
Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...
Tiny pores at a cell's entryway act as miniature bouncers, letting in some electrically charged atoms--ions--but blocking others. Operating as exquisitely sensitive filters, these "ion channels" play a critical role in biological functions such as muscle contraction and the firing of brain cells.
To rapidly transport the right ions through the cell membrane, the tiny channels rely on a complex interplay between the ions and surrounding molecules,...
The miniaturization of the current technology of storage media is hindered by fundamental limits of quantum mechanics. A new approach consists in using so-called spin-crossover molecules as the smallest possible storage unit. Similar to normal hard drives, these special molecules can save information via their magnetic state. A research team from Kiel University has now managed to successfully place a new class of spin-crossover molecules onto a surface and to improve the molecule’s storage capacity. The storage density of conventional hard drives could therefore theoretically be increased by more than one hundred fold. The study has been published in the scientific journal Nano Letters.
Over the past few years, the building blocks of storage media have gotten ever smaller. But further miniaturization of the current technology is hindered by...
With innovative experiments, researchers at the Helmholtz-Zentrums Geesthacht and the Technical University Hamburg unravel why tiny metallic structures are extremely strong
Light-weight and simultaneously strong – porous metallic nanomaterials promise interesting applications as, for instance, for future aeroplanes with enhanced...
11.12.2017 | Event News
08.12.2017 | Event News
07.12.2017 | Event News
14.12.2017 | Health and Medicine
14.12.2017 | Physics and Astronomy
14.12.2017 | Life Sciences