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Detecting What Lies Beneath


Robots that graze in the wild may soon help clear minefields, writes Jonathan Heddle.

Lying on a patch of rocky earth, in Chiba, just north of Tokyo, is a large machine about the size of a dinner table; it could be a small tank if it wasn't for the six legs aligned, insect-like along two sides of its rectangular body. Slowly, the machine rises up onto its feet and walks forward like a giant, silver beetle.

This is not a creature from the latest Godzilla movie but a robot under development by scientists at Chiba University. If all goes according to plan, their test ground could soon be exchanged for the deserts of Afghanistan and Comet III could be working to help solve one of the country's biggest problems.

There are some 10 million landmines scattered across Afghanistan, mainly laid by Soviet forces and their allies between 1979 and 1992. According to an Oxfam report, they kill 150-300 people each month. (Globally 800 people per month are killed and 1,000 more maimed due to accidentally triggering a hidden mine.)

Mine-clearing is a slow and dangerous business. Typically, workers crawl along the ground, probing it repeatedly as they inch forward. One person can check no more than about 50 square metres a day.

There have been some novel attempts to take humans out of the equation, including a plant that changes colour when it detects a mine's chemicals in the soil.

The team at Chiba University, led by Kenzo Nonami, has developed an intelligent robot with excellent vision, and a dual propulsion system; caterpillar tracks for fast movement and six insect legs for more delicate manoeuvres in the minefield. Comet III will roll up to a minefield, raise itself up onto its six legs and then carefully walk around, searching for mines using stereo vision, metal detectors and a ground piercing radar system.

At the moment, the robot takes more than 20 seconds to calculate each step, making it a very slow walker. ‘‘We keep asking the manufacturers to make faster processor chips,’‘ says Nonami. Within a few years faster processors will enable the robot to make almost human-speed decisions when walking. Nevertheless, the robot already manages to cover 1,800 square metres an hour.

The robot's systems need a lot of power and Comet III uses a 900cc petrol engine, which seems a little 20th century for such a futuristic robot. ‘‘We would really like to power it from a fuel cell or solar power’‘ admits Nonami. ‘‘We have even thought about a system like animals where the robot powers itself by consuming organic matter and converting it into energy,’‘ he says. Such a robot would use muscle-like actuators, which would contract and expand, much like animal muscles. Such a system is, however, even further in the future than solar or fuel cells. At the moment, Comet III has cost about 100 million yen ($1.3 million). If the design proves successful, and orders come in from around the world then the cost of each unit will drop to around the same as an average family car.

The research group is already working on two new robots. The first is a collaboration with Fuji Heavy Industries, a caterpillar-tracked robot that is due to go to Afghanistan next summer. It will use a highly advanced robotic arm with a small, jackhammer-like device to break open the soil (which in Afghanistan can be baked rock-hard), a pressurised air hose to remove loose soil and debris and a precision robotic hand which can pick up larger debris such as rocks, thus uncovering suspect mines.

Next will come Comet IV: similar in design to Comet III but with longer legs enabling it to take steps of over a metre in height. If all goes according to plan, and next year's trials in Afghanistan are successful, Comet IV or its successors could soon be crossing minefields all over the world.

Sydney (Australia) Guardian

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