MULTI-UNIT AIRBORNE DETECTION patterns that are repetitive, detected within a givenAND MAPPING OF LAND MINES area, and which match previous compiledINCORPORATING MAGNETIC AND characteristics that indicate mine placements. At theNON-MAGNETIC SENSORS heart of this approach is a pattern recognition developed for processing large sets of association pairs of image and texture data.M. Dudziak (MODIS Corporation (USA) and Moscow State University)A. Chervonenkis (MODIS Corporation (USA) and 1. INTRODUCTION Russian Academy of Sciences, Moscow) In developing a novel approach to the detection ofWe describe an architecture for detecting and abandoned and unexploded land mines the initialpredicting likely land mine configurations and impetus was to devise a method to employ high-locations using two new technology developments, one sensitivity magneto-optic thin-film devices. Thesebeing an advanced airborne RPV capable of auto- have shown great promise in other areas andpiloted and manual maneuvers and the other applications of magnetic-field measurement and thecomponent being an integrated magneto-optic based intent has been to integrate this technology with othersensor and videocamera. sensor types into a platform that could be readily adapted and maintained for field applications. MODEThe Hornet RPV and its successors the Ascend-I and (Magneto-Optic Detection and Encoding) thin filmFalcon are ultra-light helicopter units controlled by RF sensors 1 are Fe-Ga substrates epitaxially grown withlinks to ground-based navigators with capabilities for Bi and rare earth substitutions and have sensitivities ofonboard Auto-Pilot and Mission Control units.Currently the Hornet, with a low-end airframe saturation magnetisation µMo = 0 … 1000 G, specificweighing 12.5 lbs. and capable of carrying a 13 lb. Faraday rotation ΘF = 2.3 grad/µm, absorptionpayload, is operable with a stabilization augmentation coefficient α = 0.35 … 0.40 dB/µm, MO figure ofgyro system and is being tested with an AutoPilot merit Ψ = 2ΘF/α > 10 grad/dB, domain wall velocityenabling semi-autonomous programmable flight. 200 … 2800 m/s, and coercivity < 0.1 Oe. 2 The role of Bi substitution is critical for a high Faraday effect andThe modular, quick-load payload assembly designed increased transparency, aiding in creation of high-for the Ascend-I RPV enables deployment of a variety contrast domain structure patterns caused by domainof sensors including multiple video and also highly wall shifts due to external magnetic fields normal tosensitive magneto-optic thin-film devices. The latter, the FVF plane. Incorporated into data acquisitionknown as MODE (Magneto-Optic Detection and devices that employ polarized light delivered via fiberEncoding) are Fe-Ga substrates. optic cables to the Fe-Ga sensor for realization of the Faraday effect and a CCD camera, these compactThe Hornet RPV is capable of fine-tuned movements sensors are, in a synchronized array, capable ofto within a meter or less from the surface and is also registering variations that indicate the presence ofcapable of maintaining both the low speed and localized ferromagnetic structures from a few metersoccasional stabilization in situ required for operation of distance. The videocamera units that are directedthe sensors. Ascend-I will operate with the same toward purely optical photography of the terrain overaccuracy but with the option of either manual or which the helicopter operates produce an image streamautomatic control. Falcon is essentially the same as that is then input into a pattern detection engine forAscend-I but fitted and programmed for UAV-to-UAV tracking likely mine locations.communication and coordination. However, it was recognized that there are manyData collected from the sensors is fed into an limitations not the least of which is the prevalence ofembedded microprocessor equipped with pattern land mines that do not contain any or sufficientrecognition hardware and software, and the results are ferromagnetic components that can be detected even bytransmitted to the control station which may be very sensitive apparatus such as the MODE sensor.anywhere from several tens of meters to a kilometer or The challenge was to devise a system whereby multiplemore distant from the RPV. sensors such as possible future ultra-compact versions 1Non-magnetic, plastic land mine detection is an order Randoshkin, V. V., Chervonenkis, A. Ya., “Appliedof magnitude more difficult and the MODE sensors Magnetooptics”, Energoatomizdat, Moscow , 1990 (inwill not detect such mines. However, an approach is Russian) 2underway to study the utility of the RPV platform for Chervonenkis, A. Ya., Kirukhin, N. N., Randoshkin,obtaining terrain mappings using the combination of V. V., Ayrapetov, A. A., “High Speed Magnetoopticaloptical and magneto-optic inputs. This method Spatial Light Modulators”, Proc 2nd Int. Symp.analyzes data for indicators of surface disturbance Magneto-Optics, Fiz. Nizk. Temp., Vol. 18, Supplement, No. S1 (1992), pp. 435-38M. Dudziak, A. Chervonenkis: MODIS Corp., 3413 Hawthorne Ave., Richmond, VA 23222-1821 USAmdudziak@silicond.com, email@example.com
of Nuclear Quadropole Resonance (NQR) 3 and enables a modular compartment (E-PAC) to be quicklyMicrowave Impulse Radar 4 could be incorporated and easily loaded or unloaded.along with a MODE sensor and video units. However,there are important benefits to having a detectionsystem as light and maneuverable as a 20-25 lb. UAV. 2. MODULAR INSTRUMENTATIONSignificant issues abound with respect to weight,power consumption, aerodynamic stability, and real-time communications, as well as effectiveness in The design of the E-PAC equipment module is integralcorrelating the UAV flight patterns (current and to the efficient use of the Hornet/Ascend for such anrecorded in the past) with exact GIS maps. The present operation as mine detection. It enables the Falcon tostudy is a very preliminary first step in addressing the be used for multiple tasks with rapid changeover ofmajor points of these issues. If it is determined that an equipment, thereby eliminating the need for a heavy,ultra-light UAV solution is feasible for such a multi- bulky, less maneuverable UAV. The use of snap-downsensor array, then the consideration of using such a velcro strips on both sides of the unit and the cagesystem for detecting abandoned mines as well as mines allows for lightweight but strong retention of the packthat are in use during active combat or other forms of in flight and reduces vibration from other vehiclelow-intensity conflict can be explored further with an substructures.actual deployment. The current E-PAC design will measure 22cm x 22cmA major design concern is how to incorporate multiple by 22cm and each E-PAC module is a same dimensiondevices that require electrical, optical, and data of 18cm x 18cm x 18cm, the cage and module shell toconnectivity, particularly additional battery capability, be constructed of molded high-strength plastic. Thereand to do so in such a way as to allow rapid and are four tracks, two on the top and one on each side,efficient changes of inspection equipment, as well as into which the E-PAC slides and over which the velcroappropriate communications with a ground control strips are placed. The front and rear of the E-PAC isstation. This problem has been addressed through the completely open for freedom of line of sight fordesign of a modular equipment case and interfaces to cameras. Figure 5 illustrates the basic E-PAC design.enable an operator to rapidly exchange one module foranother without a large amount of manual intervention. While the components contained within the E-PAC may vary, there is a uniform external interfaceThe Falcon and Ascend-I UAV designs, based on the provided from the E-PAC to all other subsystems thatHornet, offer the framework for making such an may require onboard real-time communications andapproach feasible. The Hornet is shown in flight this is positioned on the top surface of the E-PACwithin Figure 1 below. A comparable system (the AC- module. There is also a uniform internal interface for100F Orion) is illustrated in Figure 2 and the subsystems contained within the E-PAC. TheHummingbird from Aerobotics Corporation in Figure redundancy of these hardware interfaces is offset by3, 5 also suited for the addition of an equipment module the convenience in designing instrumentationin the lower forward carriage of the helicopter. By applications to be packaged in the E-PAC. Figure 6customized replacement and re-machining of the shows the layout of these interfaces.airframe, the Hornet is significantly lighter andequipped with a slide-/snap plastic cartridge frame that While most of the interface components are standard PC industry protocols, four fiber optic connectors are3 NQR research has been advanced for explosives also included, two for input and two for output. Thesedetection and is the subject of work sponsored by the are not data lines but strictly for transmission ofU.S. Defense Advanced Research Projects Agency polarized light for use in the MODE sensor or for other(DARPA), the U.S. Army, and Oak Ridge National devices that may be included in an E-PAC module.Laboratory (ORNL). Cf. http://www.ic.ornl.gov/rd- The polarized light source is locatable outside the E-groups/amg/mine_nqr.html which refers to work PAC on the Falcon airframe, powered off theconducted by the Advanced Methods Group at ORNL alternator.and Quantum Magnetics, Inc. of San Diego, CA.4 Cf. http://www.llnl.gov/str/News796.html and also There is a standardized male and female unit for eachhttp://lasers.llnl.gov/lasers/idp/mir/overview.html interface assembly, so that any E-PAC assembly can bewhich describes MIR research at Lawrence Livermore simply and efficiently, even in the dark, snapped intoLabs, and refs. 2 and 3. place with a minimum of handling and manipulation.5 Hummingbird Unmanned Air Vehicle. Cf. and therefore with a minimum of potential damage byhttp://mcwl- mishandling. This is a human factors issue oftenwww.cwlmain.org/mcwl/pa/facts/hbird.htm. “The overlooked in systems design but very important for anHummingbird is a small suitcase portable, helicopter apparatus such as FALCON used in landmine detectionunmanned aerial vehicle (UAV). It has an onboard to be useable in the real world, outside the laboratoryintelligent flight control.” Manufactured by Aerobotics setting.Corp.
3. A MULTI-SENSOR ARCHITECTURE editing applications can be performed by an operator in the field when the FALCON is on the ground. In the air the range of capability is limited, but by having theFigure 7 illustrates the fundamental system architecture full internet capability onboard, FALCON operationsdevised to provide for multi-sensor mapping of regions are simplified and a great deal of custom softwarewhere there are suspected to be land mines dispersed in engineering is eliminated. From a systems engineeringeither a regular or random pattern. The primary and management perspective, this is a major advantagecomponent is a compact Pentium-based computer that and it also affects the performance and analysis ofis a customized version of the ViA Flexible PC, tracking and sensing data including pattern recognitionnormally a beltpack wearable PC with an optional programs that can be run on optical and magneto-opticdocking station. This commercial, off-the-shelf design image data streams. Results can be processed andwas chosen because of its lightweight component transmitted from the FALCON, potentially even whiledesign, low power consumption, and ruggedized in flight (although this feature has not yet beenconstruction, as well as its ready adaptation for use designed) and certainly while the UAV is on thewith high-density, low-size peripherals and optional ground.software components such as a complete speech-to-data and GPS system that can enable a user to With the onboard processing capability, it is possible tocommunicate via voice commands with the UAV while handle the dual video stream input from the standardit is airborne. While the choice of a full-featured PC downward-view videocam and the MODE sensormodel may seem unusual in favor of a strictly videocam. The standard image stream is controllableembedded architecture, the ViA model give s the by user software parameters, adjustable in real-timeadvantage of enabling many future user interface during flight, to enable capturing and sending datafunctions and can be adapted, by some modification to either at n frames/sec. where n varies 1:15, MPEGthe E-PAC module, for in-field “docking station” use compressed, or at standard intervals based upon GPSby a member of the Falcon operations team, in keeping readings that are supplied to the E-PAC computer fromwith the “double duty, multi-function” systems design the GPS receiver attached to the UAV in its aft section.philosophy. Alternative compression besides MPEG is enabled by the Falcon’s onboard computer. In this latter mode, theThe E-PAC processing unit occupies a volume mission might stipulate one frame every 100’ ofcomprised of two sections each approximately 4.5” x motion in a linear direction.3” x 1” . The main processing element is a CyrixMediaGX and 5520 chipset running at 180 MHz, and For purposes of the initial system design the MODEthere is 32MB DRAM upgradeable to 64MB. A 30 sensor was the only other sensor considered besides thewatt-hour battery weighing 11 oz. or a 48 watt-hour standard videocam and the GPS. A BW video streambattery weighing 16 oz. are the two options for onboard is produced at 15 fps and stored on the hard drive afterpower – the maximum duration is approx. 4 hours. passing through a filter function designed to remove any frames in which there was not an indicatedFor onboard hard disk capacity there is a minimal 1.6 presence of a magnetic aberration above a minimalGB unit but a 3.2GB unit can be accommodated by the threshold. In this was excessive amounts of videosystem. There are two PCMCIA expansion slots and frame storage is eliminated. With the availability ofthe following I/O and peripheral capabilities: multi-gigabyte disk storage onboard the UAV, it is more practical to reserve most image processing, suchInput / Output: as edge detection and enhancement, for post- Full-duplex audio for advanced speech interface processing on a standard workstation. VGA support for resolutions up to 1280 x 1024 Flat-panel support for resolutions up to 800 x 600 Currently being investigated is the use of wireless Digital display interface (PanelLink) internet communications in order to transmit from Two RS-232 serial communication interfaces onboard the UAV image data while sensor data is Two Universal Serial Bus (USB) interfaces being acquired and stored. The current processor and Mouse and keyboard ports memory speeds now support this design and willPeripherals: enable the E-PAC system to operate in effect as an VGA Display including either onboard internet server. A secondary PC unit co- flat panel or head-mounted located on the UAV is a preferred solution but the Keyboard: PS/2 compatible demands of weight and power consumption are Pointing devices: pen, touch (display) undesirable. A compromise solution that should meet Audio headsets (mic/speaker) most mission requirements is to allow, by software control, the transmission to the ground station of everyThe advantage of having such a full-featured PC in the nth frame captured. Image clipping prior toE-PAC unit is that virtually any type of application that transmission can remove unnecessary image portionscan be run on a standard PC including any number of that do not include the actual sensor field of vision.internet, communications, database, and even text
4. THE UAV PLATFORM 6. MODE DEVELOPMENT AND TESTING PLATFORMThe Falcon UAV is very similar in basic constructionand design to the Hornet and Ascend-I. The basicspecifications are: It was necessary to design a laboratory workbench experimental system in order to test the effectivenessLength: 66 in. of different types of MODE thin films for magneticWidth: fuselage: 12 in. fields of varying strength and domain structure and toRotor diameter: 68 in. simulate physically the performance of different thinFrame construction: aluminum, graphite, plastic film compositions for airborne use at varying distancesWeight: 12.5 lb. base unit, 23 lbs. full load from ferromagnetic sources and in the (shielded)Maximum weight: 25 lbs. presence of EM noise produced by the UAV. In orderCruise Airspeed: 45 - 50 Kts to create a practical apparatus that would allow for aMaximum Airspeed: 65 Kts relatively high degree of accuracy in measurement asRange: 24 nautical miles well as comparison between different experiments, theMaximum Altitude: 5,000 feet MagVision Development Platform was designed and isFlight Time: 30 – 60 min. (fuel/load dependent) currently in the process of being fabricated. An illustration of the basic design is provided in Figure 9Unlike Hornet, Ascend-I and many other models, some below. This is a laboratory workbench which is not aof which are illustrated in figures 1-3, Falcon’s frame part of the UAV or the E-PAC module.assembly and all hardware have been refined forminimum weight. This requires a high level ofprecision individual parts machining on a custom basis 6. VIDEO MAPPINGalthough in a production environment this would beprovided through the parts manufacturers. Modeled somewhat after the use of video imagery toThe capacity of Falcon to carry a load approximately acquire data on pavement and highway assets andequal to its base unit weight is one of the remarkable conditions, 6 the video mapping process consists ofstrong points of this particular design and enables the acquiring sufficient images to produce a quilt-likeentire E-PAC instrumentation concept to be a realistic panorama of the surveillance area, stored in a relationalundertaking. database structure on a post-processing workstation after download from the Falcon’s E-PAC computer. The use of the video map is to provide a second and5. MODE SENSORS critical stream of data to merge with the MODE image stream for feature extraction and correlation as part of a pattern detection operation. The goal is to isolateThe magneto-optic sensor unit consists of a 9cm x 3cm characteristic textural variations in the terrain featureswafer section of the MODE Fe-Ga crystal secured with that are visually detectable which may be correlated toa retaining clamp in the base of a plexiglas frame. A magnetic readings from the MODE data stream, orpiezo-controlled actuator moves the CCD video unit in which by themselves can stand alone as evidence ofa cycle of snapshots of four areas on the sensor probable disturbance patterns in the earth surface.surface. The polarized light source is input in-planewith the sensor. As the video captures a frame of one Creating a full-surface video mapping of thequadrant, magnified at a user-controllable scale from surveillance area is aided by the tagging of each video1x to 10x, by software control of the videocam unit, the frame with a GPS identifier that is used by post-light passes through the sensor and generates output processing software to control the proper fitting andwhich, in the presence of a magnetic field of sufficient trimming of images. A smoothness evaluation of eachstrength, manifests the Faraday Effect, visible as a frame for which there are redundant areas covered bymodulation of the grayscale image field. other frames is used to aid in selecting which of several redundant frames should be saved or rejected. In thisThe basic architecture is similar to that of sensors used manner the frames of best resolution are used. Becausein the detection of magnetic fields in currency and of the higher number of variables (UAV speed,other forms of secure paper, an initial application of the altitude, pitch, roll, raw, etc.) there is a significantMODE technology and the MagVision sensor/scanner amount of normalization required in order to fit theproduct. A laboratory image of an image made with a image stream together in such a way as to have aMODE sensor (size 12mm x 3mm) scanning a test reasonably uniform scale and “flow” from one imagemagnetic strip is shown in Figure 8 below. The imagewas produced using a Winnov Videum-AV processor 6 Cf. Roadware Corporation and the ARAN andcard (ISA interface) on a Pentium-200MHz PC. WiseCrax data collection technology for highway management; web site @ www.roadware.com
to the next in both the x and y axes. This critical stage landmines indicated over the background video mapof image processing is necessary in order for both the produced from the Falcon video coverage. Each suchvideo images and the MODE sensor data synchronized tentative landmine element will act as a “hot” graphicalfor post-processing pattern detection. link that an operator can use to bring up in tabular form, with associated video and MODE image detail, all the source features pertaining to that region of the7. PATTERN DETECTION surveyed landscape, using a standard browser-type graphical user interface.There are three stages to the pattern detection processapplied to the results of a Falcon flight. The first stage This work has been supported by MODIS Corporationis mapping and feature detection. A grid is graphically and Silicon Dominion Computing, Inc.superimposed upon the video data collected and eachcrosspoint has a specific spatial coordinate originatingfrom the GPS record. A sequence of image 8. REFERENCEStransformations is applied to the video map on aninteractive display during which process the operator 1. M. Dudziak and A. Chervonenkis, 1998, “Design ofcan identify and mark particular features that are Magneto-Optic Wide-Area Arrays for Deep-Spacerecognizable or indicative of possible disturbance. EMF Studies and Power System Control”,This is a semi-automated, semi-interactive step that International Aerospace and Astronautics Conference,results in a set of feature elements being recorded in Aosta, IT ‘98the Access database employed for this purpose.Currently both ArcView and GeoMedia are being 2. E. M. Johansson and J. E. Mast, 1994, “Three-evaluated for use in this stage. dimensional ground penetrating radar imaging using synthetic aperture time-domain focusing”, SPIE JEMThe second stage involves the automated correlation of Conference ’94the MODE data with the feature database. EachMODE frame has GPS coordinates and following a 3. J. E. Mast and E. M. Johansson, 1994, “Three-battery of thresholding and convolution steps to isolate dimensional ground penetrating radar imaging usingpotential magnetic features a new feature histogram is multi-frequency diffraction tomography”, SPIE JEMconstructed for each element of interest. This Conference ’94histogram has the following characteristics: 4. A. Chervonenkis, N. Kiryukhin, and V. Nikerov, feature diameter 1991, “High-speed coherent optical correlator based on feature area two MOSLMs”, SPIE Vol. 1614 (1991), 206-209 maximum density average density 5. V. Nikerov, Yu. Polyakova, and A. Chervonenkis, characteristic polygon 1991, “Double MOSLM neural-like coherent optical maximum brightness processor for distorted image recognition”, SPIE Vol. average brightness 1614 (1991), 210-215 refractivity index number of near neighbors} multiple 6. V. Nikerov, N. Kiryukhin, Yu. Polyakova, A. directions of near neighbors} multiple Chervonenkis, and A. Ayrapetov, 1992, “Spatial distance of near neighbors} multiple filtering on the base of two magnetooptic SLMs”, Adv. in Magneto-optics II, Proc. 2nd Int. Symp. Magneto-The third stage consists of creating an association pair Optics, Vol. 18, Supplement, No. S1 (1992), 449-452database in ascii tabular format that is used as input toa software-based pattern recognition engine known as 7. M. Dudziak, A. Chervonenkis, and M. Pitkanen,HAL (Holographic Associative Learning). The 1998, “A family of microinstruments for incorporationalgorithms in HAL are derived in part from into smart materials, energy management, and[Sutherland, 1990] and related work in applying digital biomedicine for space missions”, NanoSpace ’98holographic models to statistical clustering techniques (preprint available)and unsupervised neural networks. The HALintroduces the role of external pilot training signals to 8. A. Chervonenkis and M. Dudziak, 1998, “Highenhance synchronization among oscillating clusters Sensitivity Magneto-Optic Devices for Weak Magneticwhere each cluster is a grouping of associated feature Field Measurements and Localization”, 2nd Magneto-elements and categorizations, in this case types of Optics Conference and Workshop, Moscow Stateknown landmine features, geographic elements, or University (preprint available)probable image noise. The pattern detection process isan element of research currently in progress. The 9. J. Sutherland, 1990, “A Holographic Model ofoutput of the detector software is a modified ArcView Memory, Learning, and Expression”, Intl. J. of Neuraltype graphical map with the tentative locations of Systems, Vol. 1, No. 3 (1990), 259-67
FIG. 1 --- Hornet UAV in flight (Virginia, 1997) with Canon 8mm videocam and RF control mounted (courtesy Bert Wagner Air Platforms Unlimited)FIG. 2 --- ACF-100F Orion (courtesy Orion Systems) FIG. 3 --- Hummingbird UAV (courtesy Aerobotics Corp.) FIGURE 4 --- Highway accident scene filmed by Hornet UAV (Bert Wagner of Air Platforms Unlimited)
Runners attached to Tracks or guardrails E-PAC module shell and on E-PAC cage running through tracks built-in to forward on top and sides of frame of UAV module Open equipment area for attaching electronics and sensing apparatus. All connectivity is via E-PAC interfaces and communicates with processor onboard or at ground station(s). Open bay for sensor access. Entire E- PAC bottom is open, as are front and rear panels.FIG. 5 --- Basic schematic of E-PAC module and cage assembly for FALCON modified UAV PWR GND PARALLEL SERIAL2 SERIAL2 MVIDOUT SVIDOUT FOPTIN1 FOPTIN2 FOPTOUT1 FOPTOUT2FIG. 6 --- Basic schematic of E-PAC module and cage assembly for FALCON modified UAV
UAV Main GPS Polarize Battery Receiver Voice link Data link from from groundstation d light (serial out) source E-PAC Module ViA Pentium PC main system EM shield housing 3.2GB disk drive Enhancing Perm-Magnet 30 watt- hour Canon Canon MODE Sensor Battery Videocam Videocam (B/W) (Color)FIGURE 7 --- Basic system architecture for MODE + Video Mapping of suspected Minefield areas FIG. 8 --- Laboratory image (magnified 10x) of test high-coercivity magnetic strip Scanner Rails Adjustable Rail SampleRetainer Scanner Spacers Sample Bed Drive Assembly Motor Drive Chain Chain Sample Retainer Retainer/Pulley Scanner I/O Cable Drive Control Cable FIG. 9 --- MODE Development Workbench Schematic Diagram