Detecting hidden threats.

Author:Walters, Brian

The worldwide ban on the use of anti-personnel landmines (APL) should in theory reduce the demands made upon army de-mining units, but the reality is quite the reverse. In many parts of the world, mobile and foot soldiers must continue to fight on the assumption that APLs and anti-tank mines have been laid, whether by a disciplined enemy or by irregular forces.

The Ottawa Convention requires all APLs to be eliminated before 2010 and many countries have destroyed their stocks with great ceremony, retaining only sufficient numbers for use in training. Nevertheless, by no means have all countries signed up to the Convention, some arguing that APLs are an effective means of border security.

Meanwhile, bomblets, cargo shells or other submunitions in current use can and do scatter small devices that are similar to APLs in that their delivery is random and some fail to explode. Either way it is often civilian populations that are most vulnerable to such weapons long forgotten by those who laid or scattered them but nevertheless may remain a threat to life and limb.

Certainly, the main focus of landmine detection today is driven by humanitarian motives, and often the companies that produce appropriate equipment do so as much for defence users as the non-governmental organisations (NGO) established to clear mines from civilian areas. While a great deal of research is dedicated to finding better means of detecting mines, it must be said that the line dividing mine detection from actual mine clearance has become blurred.

That's because it is sometimes necessary to employ a flail or other mechanical means to clear vegetation from an area known to be contaminated with mines. Only then can the laborious task of checking every square metre begin. But often some of the solutions resulting from this research are impractical, if not downright bizarre.

Nevertheless, stimulated by the need to reduce casualties among demining units, or to reduce the cost of clearing minefields, the development of new sensor technologies continues. The systems proposed or in use include ground-penetrating radars; radio frequency enhanced infrared, air platform radars and laser techniques. To which should be added the widely used handheld metal detectors.

The Advanced Robotics Laboratory of the University of Brescia, Italy has been investigating the possible use of swarms of simple robots. This has the aim of reducing risks to human operators while speeding up the clearance process. However, difficult terrain such as thick vegetation would oblige surface preparation using flails, although this would also eliminate trip wires.

Once cleared, the robots would be unleashed to carry odour detectors that would find vapours given off by explosives. However, high winds can result in false readings and it seems unlikely that such swarms of robots will be tackling minefield anytime soon. The National Center for Physical Acoustics at the University of Mississippi is another institute that has devoted research to the mine detection problem.

It sees a laser-Doppler based acoustic-to-seismic method as a promising way to detect buried mines, which would...

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