vol 8, issue 1

How to... defuse a bomb

21 January 2013
By Crispin Andrews
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Explosives rig

Rigs such as this one are used to analyse the effects of explosions on human body parts

A large pile of old land mines

Wheelbarrow robots can be used to locate bombs, including land mines

Staff from the Royal British Legion Centre for Blast Injury Studies

The Royal British Legion Centre for Blast Injury Studies is using simulation to monitor the different effects of a bomb blast

With the use of IEDs and landmines increasing in modern warfare, bomb disposal specialists are turning to cutting-edge technology.

During the First World War, when military forces deployed their first bomb-disposal units, wars were fought between soldiers on the battlefield. Even during the Second World War, when aerial bombardment of cities, towns and villages meant defusing bombs became a necessity to protect civilians as well as military personnel, most of the fighting was done by and between visible combatants.

Today, faceless insurgents use bombs against military and civilian targets. Lacking the capacity to meet their enemies head-on, they hide in the shadows, inflict hit-and-run attacks and hope to win small victories. Against an overwhelmingly superior force with more soldiers, better weapons and more money, terrorists, freedom fighters ' call them what you may ' aim for what they see as their governmental opponents' soft underbelly: the civilian population. Inflict enough death and destruction there or, better still, instill into the population the fear of potential death and destruction, and the strongest of nations may be influenced and even defeated. Or so the theory goes.

It doesn't often work like that, though. Government military forces simply devise strategies to combat these new threats and, of course, train personnel to implement them.

In Afghanistan, Captain James Fidell of the Royal Logistics corps and his bomb-disposal team would, on average, defuse a bomb every third day. "There were times when we'd work back-to-back, up to seven [bombs] a day, and others when there was a lull, with less to do," he says.

In August 2010, Fidell was sent to defuse a bomb under the Bandi Barq Road, to the north east of Gereshk, in southern Afghanistan's Helmand Province. The road is an important route for locals and allied forces. It has a concrete surface, which is very difficult for the Taliban to lay bombs on.

"Had we detonated the device, not only would it have hurt the local economy and our mission, it would also have made it easier for the insurgents to plant more devices in the crater," he says.

There was no other option. Fidell had to deactivate the 50kg explosive device by hand.

Render-safe procedures

Of course, it's not just in Afghanistan that bombs are a threat. On any given day, someone, somewhere, military or police, will successfully defuse a bomb, saving lives and property.

On 2 December Pakistani security forces defused a bomb left outside a police security checkpoint in Peshawar. Three weeks earlier, also in Peshawar, experts disposed of two devices, and two more in Karachi. On 5 December, in the Khyber region of the same country, security dealt with a bomb left outside a local politician's house. The day before, the Syrian Army defused four bombs in Eastern Ghouta. The previous week, reports from Iraq said that 44 people were killed by bomb blasts.

Former Royal Engineers bomb-disposal expert Richard Stevens explains that there are standard 'render-safe' procedures. The military doesn't let on what these procedures are, though. Nor does it divulge anything about its training procedures. "If we did, it would be too easy for our enemies to alter their device design," Stevens says.

Truro is hardly Tora Bora, but last October a Royal Navy bomb disposal team rolled in to the Cornish town after someone spotted something suspicious on the High Street. The team used a remote-controlled 'wheelbarrow robot' to check the device. It turned out to be a camera in a lunch box.

Wheelbarrow robots

Fitted with cameras, microphones and sensors for chemical, biological or nuclear agents, wheelbarrow robots have hand-like manipulators to open doors and to handle or move explosive devices. They've been around since 1972, when the British Army started using them to help defuse IRA bombs in Northern Ireland, but are now being phased out by new designs

'Cutlass', unveiled last August, looks like a wheelbarrow robot and has variable speed. With more powerful cameras, operators can stand further away from the target device, while the robot can also automatically change the tool on the end of its extendable arm. The arm has nine joints, which are instructed and controlled by the software.

A linear actuator lifts the robotic arm to provide extra power to the internal base axis rotator gear. This maximises performance and helps counteract the turning moment created when the arm tries to lift a load when extended. An on-board lithium-ion rechargeable battery powers the robot's motion axes, including the six drive-wheels. The six-wheeled design offers mobility on all types of hard and soft terrain and in all weather conditions.

Experts can't always use large robots to dispose of bombs. Robots are heavy and insurgents often put their devices in places inaccessible to the vehicles needed to carry them around. "Some bomb-disposal experts work on foot, and carry their equipment in a rucksack," Stevens says.

'Dragon Runner' is a lightweight British military robot small enough to fit in a backpack. With wheels or twin-tracks, it can operate on smooth or rough terrain and even climb stairs.

It has the same equipment as the bigger robots: cameras, motion detectors and microphones. It also sends video footage back to the operator's handheld device. The operator then views each shot on screen, separately, or all four in a grid. When configured with a manipulator arm, Dragon Runner can dig around suspicious objects as well as pick them up and move them.

Robots keep the experts safe, but they tend to blow up the device and whatever's near it. To actually defuse a bomb requires precision movements. Sandia National Laboratories of Albuquerque, New Mexico, has developed a robot hand that it hopes has the dexterity to dismantle explosive devices, preserve evidence, and allow the human expert to work at a safe distance.

Remote-controlling glove

Funded by the US Defense Advanced Researched Projects Agency (DARPA), the hand, attached to the robot, is controlled remotely by a human wearing a rigged-up glove. The robot hand is covered in soft gel, which grips objects like human skin does. Previously, robot manipulators have found small, flexible or slippery objects and materials difficult to handle.

The digits attach to the palm through magnets. In an accident, they snap off at a magnetic point of contact, rather than break, and can easily be reattached. They also bend backwards for greater flexibility. Screwdrivers, lights and other tools can be attached in place of the robot hand's fingers.

Bomb disposal used to be a specialist role in the military. But since 2001, more than 50 per cent of British troops killed in Afghanistan have fallen victim to roadside bombs and land mines. "Bomb disposal is now part of generalist training," says Stevens. "These days all personnel have to know about it and anyone can volunteer for training."

The MoD has started using computer gaming technology to train its future experts. A simulator, developed by the University of Birmingham and the Defence Science and Technology Laboratory, depicts a typical UK town with a petrol station, shops, office blocks, a multi-storey car park, a railway station, an industrial area and a school ' plenty of places for insurgents to place their virtual bombs.

Trainees get the same first-person view they would have in the field from the robot's camera. For example, if someone spots a suspect package in the boot of a car, the operator can drive a virtual Cutlass robot up to the car, open the boot or door and search it.

The scenarios also help trainees learn how to interact with witnesses and the police and set up safety cordons. "The simulators are designed to give future specialists the wherewithal to plan their render-safe procedures," says the University of Birmingham's Professor Bob Stone.

Simulation training

The German army has been using bomb-disposal simulators to train new recruits for several years. Captain Heinz Lichtner, instructor at the Bundeswehr's Centre for Explosive Ordnance Disposal, explains that using simulators means trainees don't have to worry about damaging expensive equipment.

"If you use a real machine in training, a slight inattention or maladjustment, for example in the vertical clearance of an opening, can result in thousands of euros' damage and the machine being out of action for some time," he says.

Microphones in the German simulator pick up ambient sounds and the noises made when a vehicle travels over different surfaces. Instructors can also change the virtual environment and make the virtual robots malfunction. Recruits learn how to estimate distances via the robot's monitor and how to work out correct orientation, via a screen shot, in unfamiliar situations.

Lichtner adds that that the biggest challenge for bomb-disposal trainees is to select the correct operating device in the correct way. "If the robot is near an object that you only want to have a close look at, you must be very careful not to touch a wrong button and unintentionally move the object, as it could be touch-sensitive and explode," he says. "If you do not correctly assess the ground you're driving on, the robot can get stuck or, even worse, tip over. Then the expert has to move forward (to pick it up), losing the advantages of using a remotely controlled vehicle."

The German simulator has 13 training scenarios. The Birmingham University team is currently considering additional airport and stadium situations. They have already designed a virtual Afghan village.

Richard Allen, from the Ministry of Defence's Counter Terrorism Science and Technology Centre explains that simulation won't replace hands-on experience. "With complex equipment such as remote-controlled vehicles, the guys ultimately have to be confident they are able to do the job for real," he says.

As Captain James Fidell worked on the Bandi Barq Road bomb, the troops covering him came under fire. It took him eight hours to defuse the bomb, in pitch dark, in a small tunnel. Fidell is 6ft 5in. Space was so tight under the road he couldn't wear his bomb disposal suit, helmet or body armour.

In March 2012, Fidell received the Queen's Award for Bravery. Last November he was made CBE.

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How to defuse a bomb in 5 easy steps

The military don't let on about how their operatives defuse bombs. If they did, the people who plant them would simply change their devices. Strategies aren't fixed, either. What bomb disposal operators do will largely depend on the situation, the type of device, the timescale and the equipment available.

When an explosive device is reported, the options are as follows:

1 Can it be avoided? Can the unit find another route to get to where it needs to go? In war, time in which to achieve an objective can be limited and it can take several hours to remove a device so it may be quicker to find another way.

2 Use remote means to identify the device. Robots or unmanned aerial vehicles relay information to operators about the type of device and its threat.

3 Use remote means to destroy the bombs. Robots or unmanned aerial vehicles safely detonate the device.

4 Use remote means to remove the device in a container. Useful when the authorities need to get information from the device to identify who put it there. More useful in the West where the authorities have fingerprint and DNA database. Less so in places like Afghanistan, where such information is limited.

5Defuse manually. This is perceived to be a last resort, only to be employed in immediate life-threatening situations.

Simulation: Understanding blast effects

When a vehicle is struck by a mine, the floor tends to rupture and occupants with their feet resting on the floor experience an impact so severe that frequently it leaves them with terrible injuries to their legs and lower bodies.

The Royal British Legion Centre For Blast Injury Studies at Imperial College London has carried out tests on post-mortem human limbs to better understand the effect of these blasts, and how new technologies might protect combatants against them.

The centre's injury simulator replicates anti-vehicle mine blast loading. A pneumatic test rig capable of accelerating a 42 kg steel plate to 20m per second and back to rest within 20ms, simulates the effect of a typical mine blast on a person's leg, through a vehicle floor.

The simulator uses a pressure sensor, an accelerometer and an acoustic sensor to monitor the explosion. Scientists fix strain gauges to various bony cadaver parts and sample all of the synchronised sensors at a 25kHz frequency. They manually trigger data acquisition with a push button, moments after the rig fires.

Imperial College used National Instruments' PXI Computer and LabView system design software to help analyse the data they acquired. "Each of the sensors Imperial used provides 25,000 readings a second," says Kyle Voosen, NI's marketing director. "You can't just replace a cadaver if things go wrong."

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