Mine detection and sensing technologies-new ... - IEEE Xplore

IECON'O1 : The 27th Annual Conference of the IEEE Industrial Electronics Society

Mine Detection and Sensing Technologies - New Development Potentials in the Context of Humanitarian Demining Maki K. Habib Monash University School of Engineering and Science Bandar Sunway, 461 50 Petaling Jaya, Selangor, Malaysia. [email protected]

Abstract

1. Introduction

Humanitarian demining aims for a total clearance of all types of landmines from infected areas and infrastructures as efficiently and as safely and as rapidly as possible while keeping cost to minimum. It requires that each individual mine in an area to be located, uncovered and removed or destroyed. The focus is to make these areas economically viable and usable by the people for different activities and to allow people to use their land without fear. The targets of mine detection and sensing technologies are to achieve a high probability of detection rate while maintaining low probability of false alarm. But, the probability of false alarm rate is directly proportional to the time and cost of demining by a large factor. Careful study of the limitations of any detection and sensing capabilities with regard to the location, weather, environment, and soil composition is critical along with the required technical operation and maintenance skills, while keeping in mind that not all high-tech solutions may be workable in different soil and environmental conditions. Wide variety of mine detection and sensor technologies has been developed while others are in varying stages of development. But it is clear that no single available technology has the capability to detect and recognize a variety of mines under all situations. Also most of these methods and techniques are very slow, have low accuracy, complex and large in size, andor expensive and suffer from a high false alarm rate. Due to this, some efforts are even trying combinations of various new technologies, and some are combining their new techniques with ordinary metal detectors and other sensors to increase the sensitivity of their particular methods. This paper presents the landmine problems, the problems facing humanitarian demining, priorities and an evaluation of mine detection techniques and technologies along with their new development potential in the context of humanitarian demining. Keywords: Landmines, Antipersonnel Mines, Demining, Humanitarian Demining, Mine Detection, Sensing Technology, Sensor Integration, Data Fusion.

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An antipersonnel mine is a device designed to kill or

injure anyone that comes into contact with it through direct pressure or a trip-wire. Anti-personal mines are harmful because of their unknown positions and they are varying from each other by the explosive load, the activation mean, the action range, and the effects they have on human body. Modem landmines are fabricated from sophisticated non-metallic materials such as plastic and wood, and incorporated advance electronics. The diameter of a mine is often less than 10 cm with mainly plastic content, and its life cycle exceeds 75 years all for few bucks varying from 3.0-30.0 $US. The fact those many of current mines are plastic means that they can float in water, and they are all but undetectable by many in-service mine detectors. Longevity of a mine, easiness to deploy by scattering them without much effort, and low cost is attractive parameters for those using the mines. It is estimated that there are currently more than 100 million landmines scattered over more than 68 countries and that 800 people are killed and 1,200 maimed each month by these weapons. Currently, there are 2-5 million new mines continuing to be laid every year. By the end of year 2000, there will be about 120 million mines uncleared, with the number still increasing. Additional stockpiles exceeding 100 million mines are held in over 100 nations, and 50 of these nations still produce a W h e r 5 million new mines every year. The rate of clearance is much slower, as it is estimated to be 100 thousand mines per year, and there is clearly a great need to increase drastically this clearance rate by a reasonable factor. Mines can be designed to attack vehicles (wheels, tracks, belly, side and top attack) or people (fragmentation, bounding, directional and blast). Sometimes mines are laid in a pattern and sometimes they are buried by hand or delivered and scattered by artillery munitions. Some mines are located off-route and fire a projectile when they're disturbed. Pressure, trip wires, tension or pressure release, electro-magnetic influence, and seismic signals can detonate mines. Some landmines are "hardened" against neutralization by explosives. Some landmines have anti-disturbance mechanisms to injure or kill the mine clearance or demining personnel. Detection and neutralization are very difficult because there are over 750

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major mine types, plus variants. The favorite explosive for the main charge in landmines is TNT. Other types of explosives are used too. In addition, mines may have a booster charge to enhance the power released by the detonator to a level that's enough to initiate the main charge. Over 650 different varieties of anti-personnel land mines exist, all essentially consists of a container with explosives and a fuse in it. In a mine, sensor and the activating mechanism together make up the fuse, which can be configured in many ways. Fuse technology has evolved from simple mechanical pressure sensors to sophisticated electronic processors that may even control several mines at a time. Landmines are so easy to lay and yet getting landmines out of the ground remains a slow, dangerous, laborintensive and costly process. The root of the problem in clearing landmines is in detecting the precise location of each individual mine, and also detecting the absence of mines. Methods of detecting individual mines vary from simple manual probing to a variety of electronic technologies, including electro-magnetic induction metal detectors (EMI), thermal imager, ground-penetrating radar (GPR), thermal neutron activation (TNA) and others.

2. The Objectives Demining

of

Humanitarian

The objectives and philosophy of humanitarian demining compare to military demining are different. Solutions developed for the military are generally not suitable for humanitarian demining. The military use the term 'breaching' to describe their main mine-clearing concern. It is dictated by the strategies of warfare, tactical countermining comprises operations that allow an attacking force to penetrate or avoid mines rapidly as it attacks a target or to speedily clear areas to sustain specific operations. The pace is very quick. Individual mines need not be found, and casualties from mines and other weapons are expected and accepted. Significant resources can be brought while not all the mines need to be cleared and any clearance rate over 80% is generally considered satisfactory. Also, the military accepts relatively high risk that some of their vehicles and soldiers will still be destroyed and killed even after breaching has been completed. The time is a critical factor in military breaching. Military mine clearance equipment tends to be expensive and may be high-tech, large in size, requiring highly trained logistical personnel. The means to do so is by mechanical landmine clearance, such as, ploughs, flails rollers, tracks, etc. Mechanical landmine clearance approach is fast but it cannot assure safety and it is environmentally not friendly. With this technique, antipersonnel mines may be pushed on side or buried deeper or partly damaged making them more dangerous. The humanitarian situation is quite different. Humanitarian demining is by definition a total clearance

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of the land from all types of mines. It is carried out in a post-conflict context, and its objective is to decontaminate populated areas and infrastructure of all landmines, make land safer for daily living and restoration to what it was prior to the hostilities and to allow people to use their land without fear. The amount of time it takes to clear an area is less important than the safety of the clearance personnel. Humanitarian demining requires that each individual mine in an area are located, uncovered and removed or destroyed. Safety is of utmost importance, and casualties are unacceptable. The standard to which clearance must be achieved is extremely high as there is a need to have at least 99.6% (the standard required by UN) success (detection) rate to make sure that there is not a mine being left in the ground before letting the people stepping in again. Any system to be developed should compliment this effort, not to hamper it or simply move the problem elsewhere. The risks to those carrying out the task must also be maintained at a lower level than might be acceptable in a military situation. Another consideration by humanitarian demining is the use of land for development, i.e., reducing the environmental impact that may results from the demining operation. Currently available technologies are not suited to achieve the objectives of humanitarian demining. What is required is to have a landmine detection system that is almost 100% effective, very low cost, fast, and easy to use.

3. Challenges and Requirements Finding, removing, and destroying landmines in the aftermath of armed conflict is a prerequisite to a return an infected area to normal situation. The major problem in mine clearing is discrimination. Mines do not behave in a regular or predictable fashion, and what happens when a landmine explodes is also variable. Frequently the mine clearance technique has to be adapted to the circumstance on a mine by mine basis, which require analytical analysis to be done at a high level command. The development of unique demining technology is difficult because of the continuous change in the environmental factor, and the tremendous diversity of environmental conditions in which mines are laid and because of the wide variety of landmines (mine size and composition, burial depth, grazing angle). The weather and environmental conditions whereas mines are often laid, cover weather (hot, humid, rainy, cold, windy), density of vegetation (heavy, medium, small, none), composition of soil, type of soil (soft, sand, cultivated, hard clay, covered by snow, covered with water), and type of the terrain (rocky, rolling, flat, desert, beaches, hillside, muddy, river, canal bank, forest, trench). Also, residential, industrial and agriculture area, each has its own features and needs to be considered. The problem is complex, involving not only the detection of individual mines and pieces of unexploded ordnance, but also the decision to

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declare a given area a mine free or the delimitation of its real extension in case it is mined. Detection solutions with current technologies are often too big, too heavy, too slow to meet demining requirements, or not accurate while associated with high false rate. It is slow and expensive to transport heavy equipment over bad or non-existent roads, and spare parts are hard to get inside the infected countries. The false alarm rates depend on the areas being searched, and can reach levels of 1000 to 1. Every time an alarm is raised, a safe clearance operation must be started, and this time is wasted if the object that triggered the alarm is not a mine. A high falsealarm rate hence multiplies the demining time by a large factor and increases the cost proportionally. Given the dimension of the problem, research and development in humanitarian demining field require strategy with intensive efforts to focus on developing new approaches and technologies that enable finding and removing mines reliably and accurately, quickly, safely, and less expensively. The development of cost effective handheld or mobile platform based detection systems where the most important breakthrough is expected represent an urgent need. A promising solution to reduce false alarm rates and to overcome current landmine detection limitations will be by applying fusion of sensory information on various sensor outputs through the use of advanced signal processing techniques, by integrating different sensor technologies reacting to different physical characteristics of buried objects. Additional promising technologies supporting area detection are required too. The developed sensor(s) may work by identifying mines based on shapes, materials, explosives or combinations of them. In general the presence of explosive components is associated with all types of mines. Researchers and scientists and other member of demining community should cooperate and coordinate their efforts to help in accelerating the speed of demining, lowering its cost and reducing the deminers' risks, by providing adequate and effective sensors and tools in the field. There is a need for substantial improvements through the use of advanced signal processing methods, data fusing techniques that confirm the detection and leading to the identification of the parameters related with mines, and low-cost, lightweight, high performance computing systems. In addition, The needs to have efficient quality control methods that are reliable and accurate in proving that an area is substantially clear of mines, and to develop fast removal and neutralization techniques that are environmentally friendly. The use of information and communication technologies to enhance contact, experience and sharing data is a value-added approach.

4. Priorities in Demining Process Demining can be divided into three basic parts; locating and identifying minefield, detection of individual mine

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within the identified area and, removing the threat of the detected mine (by neutralization, removal, or detonation). To achieve a reliable and accurate results while enhancing safety, the priorities for research and development in humanitarian demining field require strategy that should start with:

1. The need to enhance the safety of deminers through suitable clothing, equipment and by isolating deminers from having direct physical contact with the mine by developing proper technology. 2. The need to develop reliable sensor or combination of sensors through sensor integration and data hsion that allow the detection of minefields along with the detection and marking of each individual mine within these fields. The developed sensor may work by identifying mines based on shapes, materials, explosives or combinations of them. In general the presence of explosive components is associated with all types of mines. 3. The use of information and communication technologies to enhance contact, experience, research, planning and sharing results and data. 4. To speed up mine detection process, an array of sensor can be integrated to cover wider area. To facilitate the work of each individual deminer, the developed sensors should be integrated with easy to carry hand held structure. 5 . For the purpose of speeding up detecting, locating, and supporting deminers safety, the sensor need to be mounted on a flexible andor semi-autonomous vehicle. This highlights the need to develop proper mechanized structure with mobility and some level of autonomy that can work in complex environment and under wide range of situations. 6. To enhance sensor and deminer performance, there is a need to develop data processing algorithms, and data fusing techniques that confirm the detection and leading to the identification of the parameters needed for the next actions within a suitable time. 7. The needs to have efficient quality control methods that are reliable and accurate in insuring that an area is substantially clear of mines. 8. Developing fast removal and neutralization techniques that are environmentally friendly.

Detection 5. Mine Technologies

Techniques

&

Landmine clearance process can be divided into three basic parts, Location and identification of minefield, Detection of individual mine within the identified area and, Removing the threat of the detected mine (by neutralization, removal, or detonation). There are almost as many mine detection methods as there are types of

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mines. Various detection technologies range from high tech to the use of hand held prodders are currently used, each with limits or flaws. Most of these methods are very slow and/or expensive and suffer from high false alarm rates.

3.1 Hand Prodding Detection and clearance in Humanitarian demining very often rely on manual methods are the primary procedure. Hand prodding is the most reliable method of mine clearing. Well-trained staff prods the ground with thin steel spikes about 25 cm long, approximately every 2cm at a shallow angle of about 30 degrees. The resistance of the probe and the reaction of the surface define where to dig the ground around and carehlly remove the mine. Clearers manually search with a metal detector and a pointed stick and when a solid object is detected, careful and small distance probing are conducted. Upon hitting something hard, the operator then try to figure out what the object is by getting a feel for the shape and size of the object. If the object is determined to be a potential-mine, a mine clearing team come-in to uncover the object and neutralized it by detonation or by removal. Prodding the ground by hand is presently the only way that guarantees an exhaustive detection of any landmine. It is very slow, extremely dangerous, painstaking work and human can not sustained a reliable work continuously for long time. The mine may have turned on its side and the prodder hits the pressure plate rather than the side and that may cause th emine to explode. A person performing this type of clearing can normally perform this task for twenty minutes before requiring a rest. One person may be able to clear between 20 and 50 m2 of land in a day. An instrumented prodder that mechanizes the operation has been developed to enhance safety and the utility of the current prodder but its practicality is not proven yet. Also, a smart probe is underdevelopment to enhance prodding performance. By using the smart probe, a deminer can tell the difference between metal, stone and plastic buried in the ground. In contact with a target, the smart probe sends an interrogating ultrasonic pulse down the needle. The return echo is digitized and processed to identify the material contacted. In this way, rocks may be distinguished from mines without excavation.

and left/right, the location of detected metal can be narrowed to within a few inches. Proximity of the sensor to the surface is usually required. Current metal detectors can be tuned to be sensitive to detect small items up to a tenth of a gram of metal at a depth of 10 cm. Unfortunately this method is often unreliable and time consuming due to high faulty alarm rates. This sensor can not differentiate a mine from metallic debris, tin cans, or bullets. Mineral composition of some soil prevents the use of metal detectors, as it will be ineffective. Normally, soil after battlefield is contaminated by large quantities of shrapnel, metal scraps and cartridge cases, leading to 1001000 false alarms for each real mine. Each alarm means a waste of time and induces a loss of concentration. Metal detectors are sensitive to metal mines and firing pins but cannot reliably find plastic mines. In spite of that, metal detectors still represent a very valuable tool in most situations. Metal detector is not subjected to error from soil moistures and other weather induced variables. A normally one to several meters wide metal detector arrays are employed for vehicle platforms to rapidly scan large areas. Some of these arrays may give additional information about the depth and the approximate size of a detected metal. A suspension system is also employed to make sure that the detectors are always parallel to the surface. Frequency domain (continuous wave) metal detectors and time domain (pulse) metal detectors are also . used for different purposes. A number of magnetometer and electromagnetic induction systems with novel location and pattern recognition capabilities have been developed as prototypes. Magnetometer instruments commonly used by geophysicists to measure intensities associated with ore bodies are considered to detect landmines. These sensors do not radiate any energy, but only measures the disturbance to the earth's natural electromagnetic field. Most effective type is gradiometers that can identify the signature of metal parts. Additionally, meandering winding magnetometer (MWM) is based on a technology called magneto-quasistatics, which in principle can detect the size, shape and properties of metallic objects underground by measuring their magnetic fields. A related technology called electroquasistatics is designed to discover plastic objects.

3.2 Metal Detector There are different metal detection technologies (such as balanced bridge and metallic induction), but the basic concept is the same. The metal detector is the most popular sensor to detect mines. They are coming in different size and with different sensitivity. It is electromagnetic sensor exploiting low frequency electromagnetic fields up to roughly few hundreds kHz. These devices rely on the influence of nearby ferromagnetic objects either via induced or residual magnetization. By moving the detector head forwardhack

3.3 Brute-Force Based Mechanical Detonation Methods Mechanical methods (ploughs, rakes, heavy rollers and flails mounted on heavy equipment such as tanks, and explosive breaching methods) are generally effective in clearing a path for soldiers and vehicles through a minefield in time of war. The ploughs and rakes destroy the ground, or only push the mines out of the way, leaving them armed. Flails and heavy rollers are effective at destroying simple mines, but smart mines can avoid them, and detonate only the second or third time they are run

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over. Clearing mine fields by modified tanks or trucks is also a common method. It doesn't need sensors and is efficient on a suitable ground. Chains attached on a rotating roller are hitting the ground in order to explode or destroy mines. Another possibility is to mount ploughs in front of a tank, which dig out the mines and moves them away, mostly without exploding. High cost, low accuracy, low maneuverability due to their size, need of maintenance prevent the wide use of this equipment within the inflicted regions. 3.4 Dogs, Rates and Artificial Tracing Explosive Detection Dogs are considered so far the best detector of explosives. Their sensitivity to that kind of substances is estimated to be a factor of 10,000 higher than for a man made detector. Specially trained dogs are used to detect the characteristic smell of the explosives in mines. Success has been reported from South Africa and Afghanistan, more in locating the edges of minefields than in finding individual mines where dogs can become confused if they can smell explosive coming from several sources at once, and due to long working hours. Trained rats may be the best and cheapest forms of landmine detector. Rats have certain advantages over dogs, they have a better sense of smell, cheaper to keep and maintain, and they are more resistant to tropical disease. Since they are smaller they can easily transported. In addition, they are very suitable for repetitive task. The main problem in the use of dogs, namely the relative small period of effective work they can provide (about an hour a day). Dogs and other sniffers have high ongoing expenses, are subject to fatigue, and can be fooled by masked scents. To save dog's energies another approach has been adopted by bringing to it the source of the scent instead of using the dog in search mode. The method has been proved successful for demining of roads. Advances in the understanding of olfaction are leading to artificial electronic noses based on an array of sensors that bind airborne molecules with only modest specificity. Understanding the mechanism of how dogs and other animals actually detect mines will allow developers to duplicate/approximate animal smell and taste organs. This will lead to enhance the ability to find a particular odor against a complex background environment, and will be a major step towards being able to move away from the electromagnetic spectrum as the only promising device for locating minefields and individual mines.

4. High-Tech Technologies

Electronic

Detection

High-tech methods of mine detection include wide range of sensors and their combinations. Examples of these sensors are, ground penetrating radar, micro-power impulse radar, passive, active and polarized infrared, 0-7803-7108-9/01/$10.00 (C)200 1 IEEE

microwave, electrical conductivity, magnetic resonance imaging, active acoustic, visual imaging radar, vision systems including imaging spectrometers, neutron activation analysis, bio-sensors, etc. Some of these sensors and their development potentials are illustrated below: 4.1 Ground Penetrating Radar (GPR) The GPR sensor includes two antennae to broadcast an active signal through the groundsoil and the other to receive the reflected signal that bounces off whatever is in the ground. Reflections from the soil caused by dielectric variations such as the presence of an object are measured. Broadcasting signal can be done by using a short pulse or a pure sine wave whose frequency is varied continuously or by steps to cover the desired range. These bouncedback echoes are plotted to trace the surface texture of the target. Homogeneous soil sends back a flat image. The mine body, buried in the same homogeneous soil, disrupts the soil density. By moving the antenna it is possible to reconstruct an image representing a vertical slice of the soil. A wide frequency band is needed to achieve a good resolution, but since higher frequencies do not propagate well, the chosen range is always a trade-off between resolution and penetration depth. For antipersonnel mines, a center frequency of 1 to 2 GHz seems to be a good choice for most types of soil. Ground-penetrating radar, at present, is a fast way of measuring changes in the electromagnetic refractive index, mainly the electrical permittivity, of the soil and its contents. Radar mainly shows that there is some electromagnetic variation not what has caused it. Water has a very high dielectric constant and greatly affects radar propagation. Conventional radar can be considered to be stationary and its target mobile, whereas the surface penetrating radar moves and its targets are stationary. Surface penetrating radar seems to have the potential to become the electromagnetic technology capable of identifying objects both on and below the surface of the ground can be done. The GPR is able to detect non-metallic materials as long as their dielectric characteristics are sufficiently different from the surrounding media. Its applications already include locating underground pipes, avalanche victims and corrosion processes in reinforced concrete bridges. The identification of specific mines at different depths and orientations and in varying soil and vegetation conditions is still a major problem facing the development of surface penetrating radar technology. A database of the radar signatures of the majority of antipersonnel mines to be detected is essential to a successful increase in the use of this most promising technology. GPRs are limited by distance from the ground surface and do not work well in conditions of high soil moisture. Performance drops off as the angle off the vertical increases. Also they are slow because every inch of the mined area must be viewed. A few emerging look-ahead GPRs promise increased standoff and detector/deminers survivability.

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improve the data acquisition and signal analysis technique used to measure the NQR response.

'Radar, particularly ground penetrating radar, appears to be a future high probability of detection sensor. New developments in sensor fusion and target recognition are needed. Antenna design, greater bandwidth range and downsizing hardware are key to the success of this technology.

4.2 Impulse Radar or Microwave Battery-operated impulse radar has been developed that is remarkably compact in size, lightweight, low power requirement and low cost. It has a wide frequency band, and works well at short ranges. These features make this sensor superior to any previous attempts to use groundpenetrating radar to detect landmines. The small footprint of the antennas allows easily to group individual units of in arrays for a faster and simplified scan and to increase coverage area of detection of minefield. The measure of the resonance frequencies of the ground to a radar impulse depends on buried objects. At frequencies whose wavelengths are comparable to the overall size of the object, the smaller details of the structure are irrelevant, making it possible to describe the shape and the material properties of an object with only a limited number of parameters. The sensor ultra-wide bandwidth is the source of high resolution imaging capabilities. More testing is necessary for this sensor under realistic condition while plans are undergoing to speed up the scan rate with advanced array. In addition, MM (millimetre) wave radar has been developed and demonstrated potential to locate mines. 4.3 Nuclear Quadrupole Resonance Nuclear Quadrupole Resonance (NQR) technology is a new mine detector aims to find buried mines. NQR uses an externally applied radio frequency. Some nuclei, such as nitrogen- 14, possess electric quadruple moments. When compounds with such nuclei are probed with radiofrequency signals, NQR can generate a coherent signal unique to certain compounds including explosives such as RDX and TNT. Accordingly NQR mine detector can detect many of the high explosives commonly used in small, anti-personnel mines. The NQR resonant frequency is specific to individual explosive compounds, resulting in a very low incidence of false alarms. Although attempts to apply NQR to land mine detection date as far back as the Vietnam War, previous efforts were plagued with insufficient sensitivity and unacceptable false alarm rates. Since it is the explosive that is being detected rather than an object buried in the ground, the number of "false positive" indications is drastically reduced. The great advantage of NQR is that it detects explosives rather than metal. Another advantage is that NQR devices can, in theory, be built and operated simply and relatively cheaply. For better performance, there is a need to

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4.4 Pulsed Fast Neutron Analysis Another technology has been put forward, which has the potential to detect specific explosives below the ground. That is pulsed fast neutron analysis. The ground is radiated with a very short neutron pulse from a plasma neutron source and the resulting gamma radiation analyzed by chromatic processing methods to identify the specific presence of an explosive chemical. Slow neutron activation of gamma rays can indicate the presence, but not much about the shape, of explosives. Fast neutrons may be used to show the spatial distribution of chemical constituents. There are issues of the high cost of both neutron sources and gamma ray detectors when compared with currently used and far from adequate metal detectors. There is also concern about the potential neutron radiation dosage received by the operator of the equipment. The technology is potentially so specific, however, that it warrants support as a medium to long-term research topic.

4.5 Optical Technologies Infrared detectors effectively detect recently placed mines, but they are expensive and limited to certain temperature conditions. Thermal neutron activation detectors are accurate but are large for field use, slow, and expensive. Active infrared can image surface scattered objects/mines such as mines dropped from the air or munitions thrown from cluster bombs. Passive infrared can be very fast, and is one of the few techniques suitable for use from aircraft. It can also work for shallow buried items if the ambient temperature is changing fairly fast. Visible Wavelengths (Hyper-spectral ImagerKASI) that detect surface laid and buried mines. Ultraviolet (UV) detector has been developed but it was abandoned after initial studies. Thermal imaging has great promise in specific locations, terrain conditions, foliage and weather. There are numerous technical enhancements available for exploration. Likewise, there is also the ability to change the characteristics of the target area using heat, cooling and water.

5. The Use of Bacteria One of the technologies for getting rid of landmines and unexploded ordnance that is now under study at ORNL could take advantage of the same microscopic, genetically engineered creatures that are also being used in waste management technologies. These bacteria can be genetically engineered to glow in the presence of certain compounds including explosives. Bacteria live everywhere, and they respond to all different kinds of substances. Biotechnologies using bacteria hinge on the tiny organisms' abilities to metabolize and break

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down organic compounds or transform heavy metals. In 1975 it has been learned that the chromosomes in bacteria can be modified to make the bacteria glow in the presence of certain chemicals. It has been tested that the bacteria, when applied to soil, would glow if the soil were contaminated with solvents like toluene or xylene. TNT is closely related to these solvents chemically, so it was fairly simple to modify these bacteria to fluoresce in its presence. The plan is to spray a solution of genetically engineered Pseudomonas over a minefield field. Landmines and unexploded shells have a tendency, over time, to leak the explosives chemicals in the parts per millions range into the adjoining earth which is just right for the bacteria. When the Pseudomonas contacts the explosives and starts metabolizing it. They will scavenge the compound as a food source activating the genes that produce proteins needed to digest the TNT. Because GFP gene obtained from jellyfish have been attached to these activated genes that include a regulatory gene recognizing TNT, the GFP gene will also be turned on. It will produce the protein that emits extremely bright fluorescence when exposed to ultraviolet light. The method has been working in lab environment. Vegetation also tends to take up the chemicals, so the bacteria glowing on the vegetation could even localize the explosives more. It would be possible to detect land mines remotely from rolling towers or helicopters by looking for glowing microbes on soil illuminated with UV light Places they wouldn't work, would include rice paddies and other wet areas, which would disperse the bacteria, and rough jungle and snow. There is a need to study the safety and the effectiveness of using the bacteria in real mine infected area.

6. Sensorial Data Fusion for Mine Detection Currently, there is no single sensor technology has the capability to attain good levels of detection for the available anti-personal mines while having a low false alarm rate in under various types of soil, different weather, all types of mines and facing many types of false targets. If one sensor can detect a mine with a certain success rate coupled with a certain probability of generating a false alarm, could two sensors working together do a better job? The idea of developing multi sensor solutions involving two or more sensors coupled to computer based decision support systems with advanced signal processing techniques is attractive and is advocated by many as a fruitful line of development. Hence there is a need to use complementary sensor technologies and to do an appropriate sensor data fusion. The ultimate purpose of a ground based approach is to come to a system that improves detection, validation and recognition of buried items by taking as input the signals of a certain number of sensors and combine their data streams into a decision minehon mine process. Here two main steps can be

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distinguished: first the presence of an object must be detected, and secondly this object has to be identified as being a mine or other. Critical to demining is the ability to distinguish fragments or stones from the target material in real time. Studying the characteristics of the data stream of each sensor separately is essential in order to extract those properties that allow discriminating between these two categories. Developing complex processors and efficient data fusion algorithms is as difficult as developing complex sensor technologies. There have already been some notable developments on multi sensor systems and on the problem of data fusion. Hence, it is essential to develop and demonstrate data fusion algorithms and human-machine interface concepts for the elaboration of a multi-sensor system to detect, localize and classify antipersonnel landmines. Projects in this area integrate traditional and currently available sensors such as metal detectors, ground-penetrating radar and infrared, and may later add further sensors such as vapor detectors, neutron sensors or nuclear quadrupole resonance (NQR). For example, the addition of a metal detector to a GPR system could help in case of doubt between a mine and a stone of the same size, which could have similar echoes. At the opposite, the GPR could differentiate a mine from debris, which could have the same amount of metal and therefore an identical answer with a metal detector. The dual technology will allow us to detect anomalies in the ground and make it easier for demining teams to correctly identify the most modem of minimal metal mines The practical implementation of multi sensor systems has a number of problems associated with it. Collocating, two or more sensors to be used together are not a simple task. The inherent higher cost of multiple sensor systems has to be watched very carefully. The data fusion and decisionmaking computations are likely to be complex. The ways in which the information is presented to the operator require development is an important issue too. Also, there is a need for high-speed processors that can handle the huge data influx from the sensors. This will be a factor while considering the processing capability for the decision support be located remotely from the sensor platform and shared by a number of detectors to keep the unit cost down, and reduce the effect of communication delay that impacting real time responsiveness. Multi sensor systems can be integrated onto hand held detector, mechanize and mobile structure (semi-autonomous robot, vehicles), and airborne to conduct advanced mine detection. Achieving these goals opens perspectives for research and development in the fields of combined sensing principles, signal and image processing, data fusion, improved human interfaces, and new platforms.

7. Airborne Detection of Mines

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In order to accelerate the mine clearance process new demining methods to detect minefields over large and varied tracts of land in a much more cost efficient, safer and reliable manner are urgently needed. Remote sensing techniques have been developed to detect minefields by the military. Since the need for humanitarian demining has increased, many of these sensors and techniques are now also available to detect minefield from commercially available platforms and sensors. The aim of this is the detection of scatter-able or pattern minefields from airborne platforms. These sensors are integrated onto manned or unmanned aerial vehicles. In order to ensure maximum likelihood of detecting antipersonnel and antitank minefields under diverse terrainhegetation conditions, different types of sensors have been used, such as, optical sensors near visiblehear infrared region, infrared (thermal) or microwave (radar) region of the electro-magnetic spectrum. The target is to produce detailed maps showing precise location of minefields. Throughout the world, there are numerous mine-infected areas whose locations are unknown. Airborne mine reconnaissance is a promising technique to use in order to reduce the time to find minefields in the first instance. This is especially true of minefields containing antipersonnel landmines plus anti tank mines laid in a regular pattern. This approach tried to detect minefields by combining the results of several airborne remotesensing sensors, that are used on test fields. Aerial photography would show where mines and UXO are uncovered or slightly covered by sand and inform mine clearance teams to do their work without the need for detection equipment. It is possible that sand cover may change during the year; so repeated photographic surveys may be useful. High precision Global Position System (GPS) registration of photographs will be essential, as there are no permanent landmarks in most areas. The performance of remote sensing should be considered over different type of landscape, with variations in relief, vegetation type and density, climate, soil type, etc. Also, there is a need to investigate the applicability of image analysis to the problem of minefield detection using airborne remote sensing images (Optical, Multi-spectral, Thermal, Radar). Different image processing methods have been applied for the detection of minefields, minefield indicators and individual mines. The proposed algorithms involve the extraction of linear features (roads, paths, fences, wires, detection of periodic patterns (e.g. regularly placed minefield indicators) and segmentation of the image in regions of interest. Different scales of airborne images (from 1/500 to 1/3000) have been investigated. The algorithms have been applied on images of a test field in Belgium and real minefields in Mozambique. The current focus is on active and passive thermal infrared imaging and passive hyper-spectral imaging in the visible waveband using a compact airborne spectrographic

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imager (CASI). CASI technique detects surface-laid and buried mines using reflectance in a large number of narrow bands over the visible and near infrared wavelengths. Remote sensing using helicopters or fixed-wing aircraft or small, unmanned, radio-controlled aircraft is being investigated. An electromagnetic induction detector on the helicopter sees signs of ground disturbance and evidence of a buried object. Is it a rock, tin can, or anti-personnel mine that could blow off a walker's leg? Infrared sensors and video cameras indicate that the object gives off more heat than the surrounding ground. A magnetometer senses the presence of metal. An on-board computer sorting through the signals from these remote sensors on a helicopter boom produces a compelling image on the screen. It tells the pilot that a landmine may be present and indicates the location. Develop a computer program to integrate the data from an array of airborne remote sensors to form an image of a land area. This visualization of the data will enable to locate buried objects and identify the ones that contain dangerous explosives. This will help to determine which land is dangerous and deserves remediation and which area is safe to develop, thus reducing cleanup costs. One potential remote-sensing method for landmine detection that has been developed at ORNL uses bacteria that emit light while eating explosives. Infrared sensors search for thermal anomalies in which the parameter can be used to detect mines by examining the heat radiated from different objects on the ground or shallowly buried. It can find an active heat source quite easily. Mines retain or dissipating heat at a different rate than their surrounding. The use of such technology for minefield identification coupled with accurate mapping of the site can be used in conjunction with other techniques to speed up the mine identification task. Developments in this technology are mainly targeted at airborne recognition of minefields.

8. Mine Detection and Technical Specifications

the

required

The main technical specifications and functional requirements that should be associated with efficient and reliable mine detector and help in achieving its target are, It should perform a combination of high probability of detection, high reliability and low incidence of false alarms. It is expected to work under wide range of weather and terrain conditions It should react on unique characteristics and signature likes features that differentiate the landmines from other objects. All types of mines are sharing the presence of explosive components, such as, TNT, RDX or mixtures of them. The sensor may accommodate this feature through the detection.

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4.

5.

6.

7. 8.

9. 10.

The sensor may work by identifying mines based on shapes, materials, explosives or combinations of them. Detects mines as small as 5 cm in diameter buried up to 6-8 inches below the surface. The need to have real-time detection (fast response time that enable fast scanning speed) of the smallest antipersonnel landmines containing explosive material. Modularized structure, local preprocessing capability, easy to interface. Compact and small size, light weight, and lower power consumption, Easy to use and maintained, easy to be replaced, and low in cost. Can be mounted of a mobile platform (ground, aerial).

9. Conclusions Mine detection is a complex and difficult task and there are many teams around the world working to solve it. Wide variety of sensor technologies for mine detection has been developed until now. But, it is clear that no single technology has the capability to detect and recognize a variety of mines under all situations. Most of these methods are very slow, have low accuracy, complex and large in size, and/or expensive and suffer from a high false alarm rate, Many technologies are promising, but none is in the sensitivity, size, weight, manufacture-ability and price range required for humanitarian demining. While some advanced technologies may show promise, it is likely to be years before they show tangible results in humanitarian clearance. Some efforts are even trying combinations of various new technologies, and some are combining their new techniques with ordinary metal detectors and other sensors to increase the sensitivity of their particular methods. Also, theoretical insight, and related development are required to move new and emerging technologies in signal processing, data analysis, artificial intelligence, diagnostics, and information technology to real-world applications and systems. Unless the reliability of these sensor technologies matches the standards of humanitarian detection, then the new sophisticated detectors are ineffective, costly and time consuming because they must be followed up by existing manual probing methods. New detection technologies need to prove their capabilities. Their development should be followed by extensive field trails in real scenarios to validate them under actual field conditions for the purpose to specify benefits and limitations of different technology. The work must be performed in ciose cooperation with end-users of the equipment and real deminers should carry out the test at a real site, in order to ensure the developments are consistent with practical operational procedures in the

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context of humanitarian demining and that it is fulfilling user requirements. Also, there is a need to have reliable process of global standard of assessing the availability, suitability, and affordability of technology with enabling technology represented by common information tools that enable these assessments and evaluations. This to be enhanced by benchmarking the performance levels to develop equipment, systems and algorithms.

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[ 161 JRC Landmine Signatures database, http:// apldatabase.jrc.it/ [ 171 Antwerp-based research group, "Rats train As landmine detectors", Belgium, Jan. 2000. [http://www.totalsports.net/news/20000 102/nu11/99123 1.090O.html] [18] B. Gros and C. Bruschini, "Sensor technologies for the detection of antipersonnel mines A survey of current research and system developments", Intel. Symposium on Measurement and Control in Robotics, Brussels, May 1996. [19] D.J.Daniels, D.J. Gunton, and H.F. Scott, "Introduction to subsurface radar", IEE Proceedings, Vol. 135, Pt. F, NO.4, August 1988, pp. 278-320 [20] Azevedo S.G., Gavel D.T., Mast J.E., and Warhus J.P., "Statement of Capabilities: Micropower Impulse Radar (MIR) Technology Applied to Mine Detection and Imaging", Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551,1995. [21] P. Ngan, S. A. Garcia, E. Cloud, H. Duvoisin, D. Long, and J. Hackett, "Development of automatic target recognition for infrared sensor-based close range land mine detector", SPIE Proceedings, vol. 2496, Orlando, April 1995, pp. 881-889 [22] G. D. Sower, and S. P. Cave, "Detection and identification of mines from na&al magnetic and electromagnetic resonances", SPIE Proceedings, Vol. 2496, April 1995, pp. 1015-1023. [23] T. Handshaw,"Multi-sensor fusion for the detection of mines and mine like targets", SPIE Proceedings, Vol. 2496, Orlando, April 1995, pp. 152-158. [24] J. R. Simard, "Improved Landmine Detection Capability (ILDC): Systematic approach to the detection of buried mines using IR imaging", in [SPIE96], pp. 489-500. [25] J. E. McFee, "Multisensor mine detector for peacekeeping: improved landmine detector concept", SPIE Technical Conference 2765, March 1996. [26] J. Smith, "Mine Detection sensors",

http://www.wood.army.mil/ENGRMAG/PB5964/smit h.htm. [27] P. Gao and L. M. Collins, "A Two-Dimensional generalized likelihood Ratio Test for landmine and Small Unexploded Ordnance Detection", Signal Processing Journal, Elsevier, No. 80, 2000, pp. 16691686.

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