Landmines are a global threat. Several countries suffer from the existence of millions of buried landmines in their territories. These landmines have indefinite life, and may still cause horrific personal injuries and economic dislocation for decades after a war has finished. Landmines came into widespread use in the Second World War, where they were designed to injure/maim rather than to kill, with a view to stressing the medical resource of the enemy. Many were left buried in the ground in regions of conflict long after the fighting had ended, causing them to be inadvertently detonated by civilians stepping on them.
IED’s have become an extremely significant and dangerous force protection issue in the wake of Operation Iraqi Freedom (OIF) and the Global War on Terror (GWOT). Insurgents and terrorists are using a variety of asymmetric techniques to attack militarily superior coalition forces with military ordnance components combined with commercial off the shelf explosives, electronics, and digital subsystems.
Landmines, improvised explosive devices (IEDs), and other homemade bombs struck 6,461 people worldwide in 2015, killing at least 1,672, according to a report by the International Campaign to Ban Land Mines and Cluster Munition Coalition. Survivors are often left with devastating injuries. In a study published in BMJ Open, 70 percent of people hit by IEDS in Afghanistan required multiple amputations. According to the UN Mine Action Service, landmines kill 15,000–20,000 people every year (mostly children) and maim countless more across 78 countries.
There have been several reports of landmines found on the Myanmar-Bangladeshi border in Rakhine State. But after a high profile campaign, 162 countries signed the 1997 Ottawa Treaty pledging to stop their production and use. The use of landmines is illegal under the international Mine Ban Treaty, but Myanmar is one of 32 countries, including the US and China, that have yet to ratify the treaty. Bangladesh, however, has signed the treaty.
Myanmar military spokesperson Brigadier General Zaw Min Tun has said the Arakan Army (AA) presents a major threat because the ethnic armed group now uses modern technologies in the violent conflict in Rakhine State. “Bombings can be carried out via mobile phones and walkie-talkies, so we need to pay greater attention to security,” said Brig-Gen Zaw Min Tun. He made the comments in response to a recent report by Indian intelligence agencies that the AA is using Bluetooth and Wi-Fi technologies to trigger landmines targeting the Myanmar army. “We have technology that can counter [AA] attacks but technology can’t guarantee 100 percent security. Terrorists will study how defensive technologies are used and attack the places that are technically weak and less protected,” said Brig-Gen Zaw Min Tun.
The demining has two contexts, the military and the humanitarian. The main aim of the military is cleaning the path where the soldiers are going to walk through. Instead the humanitarian must clear the zone of mines to ensure the life of every member of the community who lives close to the danger region. “There are literally millions of anti-personnel mines in the ground in places where people need to grow food, or need to walk to the nearest well, or simply go about their daily business – shelter under a tree from the Sun,” explains Bill Lionheart, a mathematician at the University of Manchester in the UK.
Demining efforts cost US 300–1000 USD per mine, and, for every 5000 mines cleared, one person is killed and two are injured. Thus, clearing post-combat regions of landmines has proven to be a difficult, risky, dangerous and expensive task with enormous social implications for civilians.
Many technologies and techniques have been employed in detection of landmines. Each method has its advantages and inconveniences. One of the earlier and most used methods is the metal detector. Due to electrical induction phenomena, this type of detectors is able to detect the objects that contains metal under the soil. Although this technique is cheap, it has several drawbacks: it detects all metals, either landmines or inert metals so it has very high false alarm rate; new landmines contains less metals so they are harder to be detected.
Many technologies are used to IED Neutralization and Detection (INDET) for ground forces protection against remotely controlled improvised explosive devices (IED) and related insurgent/terrorist explosive threats. Robotic vehicles and drones are also being increasingly employed for mind detection and clearing, to reduce the risk to the personnel.
Mines and IED
A land mine is an explosive device concealed under or on the ground and designed to destroy or disable enemy targets, ranging from combatants to vehicles and tanks, as they pass over or near it. Such a device is typically detonated automatically by way of pressure when a target steps on it or drives over it, although other detonation mechanisms are also sometimes used.
Each landmine consists of three components; the case which may be metal, wood,plastic or mixed, the explosive material which may be TNT, RDX, mixed RDX/TNT, Tetryl, or other high explosives, and an initiator which may include a pressuresensor, an electronic sensor or any other sensor.
A land mine may cause damage by direct blast effect, by fragments that are thrown by the blast, or by both. Blast landmines are buried close to the surface of the soil and are generally triggered by pressure. When a person steps on a blast mine and activates it, the mine’s main charge detonates, creating a blast shock wave consisting of hot gases travelling at extremely high velocity. Fragmentation mines release fragments in all directions, or can be arranged to send fragments in one direction. These landmines can cause injuries up to 200m away and kill at closer distances. The fragments used in these landmines are either metal or glass. All anti-tank mines are blast mines, because the goal of the anti-tank mine is to destroy the tank’s tracks and body.
All these mines are all made to military specifications and planted in patterns so that they can be recovered later. When detected, the disarming procedure is known and safe procedures developed for handling them.
An improvised explosive device (IED) is a bomb constructed and deployed in ways other than in conventional military action. It may be constructed of conventional military explosives, such as an artillery shell, attached to a detonating mechanism. IEDs are commonly used as roadside bombs. An IED has the operative word being Improvised. There is no specifications for the explosive, detonator or trigger. It is simply made from whatever is at hand. There is no specification for the type of explosive, the amount of explosive, the type of detonator, or the trigger mechanism. All is simply what happens to be at hand.
IEDs are triggered by various methods, including remote control, infrared or magnetic triggers, pressure-sensitive bars or trip wires (victim-operated). In some cases, multiple IEDs are wired together in a daisy chain to attack a convoy of vehicles spread out along a roadway.
Irregular armies often produce these explosive devices without design standards using low cost methods. This is the major challenge for detection technologies that must be capable of detecting also non-metallic materials and objects with different dimensions and shapes.
When a landmine explodes, the impact of the explosion weakens as the distance increases from the mine. The blast wave generated by to explosion has a peak power at the beginning and loses its power while moving in the atmosphere. Accordingly, it is possible that get a high killing power from a mine containing small amount of explosives in close contact, (for example, a mine under the foot) while encountering considerably less damage from a significantly bigger dangerous charge a few meters away.
The types of close contact injuries inflicted by improvised explosive devices (IEDs) are much more serious than those associated with land mines, finds research published in the online journal BMJ Open. The mechanism of injury is the same for landmines and IEDs, while the seriousness of injuries for either device depends on how close the victim is to the centre of the explosion, say the researchers. But they suspected that pattern 1 injuries—those where the victim suffers the full effects of the explosion at close quarters—would be more serious when they involved IEDs.
There are two distinct types of demining; military demining and humanitarian demining.
Military Demining: The target of military demining is to detect and remove a sufﬁcient number of landmines to create a safe corridor for troops and/or vehicles to move through.Armed forces can accept some losses as an expected part of the conﬂict. Therefore,a ﬂail machine, which has an 80% clearance success rate, can be used. This sort of clearance operation is not suited for humanitarian demining.
Humanitarian Demining: The target of humanitarian demining is to free the entire land area from landmines.The United Nations (UN) has speciﬁed a landmine clearance standard of 99.6% forhumanitarian demining.
The demining process has 3 key steps: detection, excavation and detonation. The current status quo for demining in post-conflict areas is manual detection using metal detectors and prodders, trained animals such dogs and rats to detect explosives, and mechanical clearance using armored vehicles equipped with flails, tillers, rollers or similar devices.
Depending on how deep the mine is buried in the ground it can take up to an hour to excavate just one landmine or UXO. This is on top of wearing 5kg of protective gear, often in the sweltering heat. One wrong move is the difference between life and death for manual deminers, resulting in 63.8% of humanitarian mine clearance casualties from 2005 to 2010.
Landmine detection technologies
Many technologies have been employed in detection of landmines from metal detectors to search for booby traps, ground penetrating radar, acoustic and Electric Impedance Tomography (EIT) to Infrared Imaging Systems. Each technique is suitable for detection under some conditions depending on the type of the landmine case, the explosive material, and the soil.
Generally, most of the landmine detection techniques consist of three main units; a sensor to capture a signature of the landmine, a signal or image processing unit to arrange the acquired data and a decision making unit to decide whether a landmine exists or not.
Researchers in physical, chemical, and biological sciences are studying and developing new methods that could reduce the false alarm rate and maintain or increase the probability of detection for mine clearance. The sensor may be electromagnetic, acoustic, nuclear, biological, chemical or mechanical.
A small percentage of the explosive manages to get out, as vapor, through fissures and shield structures of mines. The idea is to detect the presence of vapor from explosives. There are two research lines in this topic: biological and chemical.
Biological sensors or biosensors such as dogs, some rodents, honey bees, sometypes of plants and some types of bacteria depend on the possibility of direct sensing of explosive compounds.
Rats Are Being Trained to Sniff Out Land Mines
Apopo’s African giant pouched rats—or “hero” rats—are being trained to sniff out and detect TNT vapor in the ground. They’re bred and raised at the organization’s headquarters in Tanzania, and those used to detect land mines have already worked in Mozambique and Angola.
“They have a very keen sense of smell and there is no problem for them to find the land mines,” says TeKimiti Gilbert, head of mine action at Apopo, a Belgian organization that trains rats for humanitarian purposes. “The advantage of the rats is that they don’t look for metal, they look for explosives.”
WPI to develop underground bomb-detecting bacteria for Raytheon
Waltham defense contractor Raytheon has partnered with Worcester Polytechnic Institute to develop bacterial strains to detect buried explosives by glowing if they find any.
The project, dubbed The Subterranean Surveillance program, will use synthetic biology to create two strains, according to Raytheon, with one detecting the presence or absence of explosives buried underground and then the second strain producing a glowing light on the surface. With this biotechnology, remote cameras or unmanned aerial vehicles can then be used to survey large areas for the luminescence
Synthetic biology combines principles of electrical engineering with computer science to modify DNA. According to Raytheon, bomb-detecting bacteria already exists, but the challenge is finding a solution to penetrate the ground to detect buried explosives and still provide an indication on the surface if explosives are found.
The Subterranean Surveillance program is one example in which advances in synthetic biology are being used to develop sensors that can reveal a variety of subterranean phenomena at a distance.
detect very small amount of explosive material that manages to escape in the form of vapors from the shield structures of mines. By using techniques like molecular diffusion and turbulence processing, these vapors can be transported. And then these can be detected by Chemical sensors by employing electromechanical, espectorpial or piezoelectric principles. Biological methods employ animals with sensitive sniffing powers like dogs, rats, insects and microorganisms to detect the presence of explosives.
One of the most common and mature systems are metal detectors. The deminer holds the handle of Electro-Magnetic Induction (EMI) detector close to the ground and sweeps it slowly around the area being investigated. Electrical current flowing through the first coil, the “transmit coil,” induces a time-varying magnetic field in the ground. This primary magnetic field, in turn, induces electrical (eddy) currents in buried metal objects. The currents from the buried objects create a weaker, secondary magnetic field. The second coil, the “receiver coil,” detects changes in voltage induced by the secondary magnetic field as shown. The detector then converts these changes in the electric potential to an audible signal.
The metal detectors fail to detect the landmines made up of plastic or which may have a very small amount of metal. Mine search also suffers from false alarms, “Only one in 2,000 found objects is a mine,” says Dr Christoph Baer from the Institute of Electronic Circuits in Bochum, who collaborates with Jan Barowski and Jochen Jebramcik from the Institute of Microwave Systems at the Ruhr-Universität. This renders the search extremely difficult.
GPR detects buried objects by emitting radio waves (ranging from about 10 MHz to a few GHz) into the ground and then analyzing the return signals generated by reflections of the waves at any subsurface discontinuity with different indexes of refraction such as at the boundary between soil and a landmine or between soil and a large rock. Generally, reflections occur at discontinuities in the dielectric constant, such as at the boundary between soil and a landmine or between soil and a large rock. A GPR system consists of an antenna or series of antennas that emit the waves and then pick up the return signal. The GPR analyzes the return signals. A small computerized signal-processing system then interprets the return signal to determine the object’s shape and position.
In collaboration with partners from South America, engineers at the German Ruhr-Universität Bochum and Technical University Ilmenau are developing a new mine clearance technology, based on ground penetrating radar. In the long run, they are aiming at creating a handheld device that will detect different mine types on rough terrain without fail and which can be used in the same way as metal detectors.
Lionheart and his team are developing ways to reduce the number of false-positives when searching for mines. “So in a way, our challenge is not so much to find mines, but to detect that something’s not a mine,” he says. For example, it is common for landmine clearance teams to use metal detectors to locate the firing pin and metal percussion caps present in many landmines. Currently, all those bits of metal have to be dug out of the ground before an area can be declared safe and, according to Lionheart, this approach would mean of the order of hundreds of years before people could get their land back.
To improve the situation, Lionheart and his colleagues have developed the technology and the underlying maths of metal detectors to develop devices that can not only detect, but also characterize metal objects in the ground. This makes it possible to disregard the signals that relate to harmless bits of scrap metal. Similarly, Lionheart’s team is developing a form of ground-penetrating radar with multiple sensors. This enables a far more detailed picture of the subsurface to be pieced together than is possible with conventional radar techniques.
These methods are unique among detection methods that identify the mine casing based on the mechanical properties and are not based on electromagnetic properties. The A/S technique is used for the detection of landmines by vibrating them with acoustic or seismic waves that are generated and received by non-contact (acoustic) and contact (seismic) transducers, respectively. The transmitting system may be composed of acoustic loudspeakers or electrodynamic shakers. When the receiver senses a reflected energy that means an object possibly a landmine is buried, and by analyzing the reflected waves the location and identity of the target body can be found. The study of these sensors has revealed that it is very powerful in the wet and heavy ground such as clay while it is inefficient in sandy soils.
Electric Impedance Tomography (EIT)
EIT uses bi-dimensional array of electrodes to generate electricity and capture signals, the conductivity distribution and anomalies of mines generate an image that can be analysed to detect metallic as well as non-metallic mines. The biggest disadvantage is that sensors must be in close contact with the surface which increases the risk of triggering the explosion of the mine.
The penetration of optical wavelengths in opaque materials is less than 1 mm, sooptical techniques can measure a soil surface property that is affected by thepresence of the buried landmines. The visible light and the light detection andranging (LIDAR) techniques are two examples of the common optical detection techniques.
Infrared radiation consists of wavelength of 0.7𝜇𝑚 to 1𝑚𝑚 in microwave regions. Infrared/hyperspectral methods detect anomalous variations in electromagnetic radiation reflected or emitted by either surface mines or the soil and vegetation immediately above buried mines. Two modes of action, including active and passive irradiation using a broad range of electromagnetic wavelengths: A passive IR system detects natural radiation from the object whereas active systems are provided with heat source and detects radiation from heated object.
Hyperspectral imaging is a trending technique in the field of remote sensing. It is based on acquiring images in quasi-continuous bands in the visible and infrared domain. By this, we get at each pixel a reflectance spectrum that help us to identify the constituents of the materials in
Thermal detection methods exploit diurnal variations in temperatures of areas near mines relative to surrounding areas. The physical activity of emplacing mines changes the natural soil particle distribution by bringing small particles to the surface, which in turn affects the way in which the soil scatters light. Systematic changes in vegetation moisture levels immediately above buried mines also may have influence. IR imaging can detect the difference between the IR radiation emitted by the landmines and the background. However thermal signature fades with long periods of time and presence of vegetation also affects the detection.
No single technique is powerful enough to provide good performance. But if used to combine two or more techniques the desired performance can be achieved.
3D Integrated Imaging to Tackle Landmine Detection
The three-year research project lead by Dr. Manuchehr Soleimani at the Engineering Tomography Lab of the University of Bath aims to provide technology that can differentiate between images of plastic and metallic elements within a single explosive device, at depths of up to 10 cm underground on varied terrain. “We aim to develop an integrated technology to detect both metallic and non-metallic landmines and to improve the speed and reliability of this process,” Soleimani said.
That integrated technology includes two different types of array, so that older, metal landmines can be detected, as well as the newer plastic landmines that have begun to proliferate. For the Electrical Capacitance Tomography part, his team used a set of 12 copper electrodes arranged in a 4×3 matrix array (250 by 250mm in total, 4mm thin) and a 12-channel capacitance measurement instrument to image the dielectric permittivity properties of objects placed in front of the sensor array. He was able to image dielectric solids at a depth of just over half the full sensor arrays length.
For the Magnetic Induction Tomography part, inductive coils and eddy currents were used to map the passive electromagnetic properties of the objects to be detected, in 3D. Here the sensors (16 air-core cylindrical coils, each 4cm in diameter) were placed in a circular shape with their axes perpendicular to the plate. 3D image reconstruction was performed based on the analysis of sequential coil excitations and responses.
“The idea is to use both imaging techniques across a range of frequencies and get a spectroscopic signature of the materials being imaged”, Soleimani said. “In effect, we could build a library of material signatures so the imaging of buried dielectric materials could yield their precise compositions. This could be associated with a matching table of known landmines to speed their identification, based on their shape and composition.”
University of Delaware using multi sensors to detect explosives from distance
Now, a research group at the University of Delaware is developing technology to detect explosive devices from a distance. Chandra Kambhamettu, professor of computer and information sciences and director of the Video/Image Modeling and Synthesis (VIMS) Lab, has received a five-year, $1M grant from the U.S. Army Research Office for this project. This work is in collaboration with a team of research scientists from Army Research Lab, Kelly Sherbondy, Brian Phelan, Getachew Kirose, Gregory Smith, John Clark, and Arthur Harrison.
Kambhamettu and Philip Saponaro, a post-doctoral fellow, are creating an augmented reality system that will use traditional cameras, thermal infrared sensing and ground penetrating radar to find and classify potentially dangerous objects from up to 30 meters away. The multi-camera systems could be deployed on autonomous vehicles, drones, or robots sent to scout the surroundings before troops move in.
The technologies complement each other. Regular cameras collect visible light, while infrared cameras detect heat and are unaffected by light, making them ideal for nighttime use, foggy conditions, and dust storms. “With infrared, you can see and understand more than you would with just visible light,” Kambhamettu said. “Some objects that are completely invisible to traditional cameras are easily spotted by the thermal cameras,” Saponaro said. “Then, with radar, you can see objects that differ from their surroundings, buried up to 3-5 inches.”The system’s radar uses radio waves to probe the surrounding environment.
The technology being developed in Kambhamettu’s lab is tested on vehicles at a military training facility. Kambhamettu and his team will gather data from the cameras, apply deep learning to the data, and develop algorithms to make target detection more effective. They will also visualize scenarios in a virtual reality environment. The goal: “Take the data, feed it into a computer algorithm and be able to tell whether a target is present or not,” said Saponaro.
This research may also have applications that extend far beyond the military. “What we’re doing here is useful for day-to-day life, too,” said Kambhamettu. For example, a device that spots hidden objects could help elderly or blind people walk more safely by alerting them to hurdles in their path.
Kathy McCoy, the Chair of the Department of Computer and Information Sciences, said, “The cutting-edge work being done in this lab has tremendous potential for significant positive impact. This particular project that involves teaming up with the Army Research Lab and using a creative battery of vision techniques to find IEDs will enable detection that goes far beyond what is currently possible. The consequences to the safety of our soldiers is enormous.”
However Mine clearance requires much more than the latest technologies
How we made Mozambique mine-free
“Mozambique – once one of the most heavily mined countries in the world – is now mine-free is a culmination of 22 years’ work, but the results will last forever. It is a beacon of hope for other countries living with a legacy of landmines,”said Calvin Ruysen the southern African regional director at the Halo Trust.
“I feel proud to see Mozambique realise this incredible achievement. It’s been a massive concerted effort from so many people: the de-miners, the survey teams, the donors and the Mozambique government,” said Calvin Ruysen the southern African regional director at the Halo Trust.
“Our challenge now is to seize the momentum towards achieving a mine-free world by 2025. This means focusing on other heavily mined countries such as Angola, Zimbabwe, Afghanistan and Cambodia. It’s not going to be easy: the de-mining sector relies on continued political will and resources. But Mozambique’s achievement is compelling and an example to other nations of what can be achieved.”
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