Robot beetle detects killers beneath the soil

Jonathan Heddle on a minehunter that walks to work
  • The Guardian,

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 being developed by a group 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.

Afghanistan is plagued by land mines. There are estimated to be up to 10m scattered across the country, mainly laid by Soviet forces and their allies between 1979 and 1992. According to an Oxfam report, they kill 150-300 people each month.

Currently, mine-clearing is a dangerous business. It's also slow. 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. Many believe that nothing can beat a physical investigation; it's just that things would be safer if humans were not involved.

Enter the robots. Japan leads the world in the production of robots, with more than half of all the world's industrialised robots as well as advanced entertainment robots such as Sony's Aibo dog and Honda's humanoid, Asimo.

The team at Chiba University is led by Kenzo Nonami. "There are almost 70 countries in the world with a land mine problem," he says. There are estimated to be more than 100m land mines strewn across the world. In most cases, the exact location of the mines is unknown. As a result about 800 people per month are killed and 1,000 more maimed due to accidentally triggering a hidden mine. In addition the minefields cause economic damage, hampering construction and tourism.

Nonami's solution is 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.

The robot's stereo vision is particularly impressive: using that alone it is able to walk to any given point without outside control, recognizing the three-dimensional shapes of obstacles and plotting an appropriate route.

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. The current pace of chip design is so fast that, within a few years processors will be sufficient to enable the robot to make very fast, 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. Unfortunately, neither of these power sources can provide the amount of energy that the robot needs. "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 100m yen (£530,000). If the design proves successful, and orders come in from around the world for 100 or more of the machines then the cost of each unit will drop to around the same as an average family car. The model that is likely to be produced when that day comes is not Comet III.

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. Employing many of the same technologies as Comet III but housed in a more robust vehicle and lacking Comet III's walking ability, it will be a proving ground for much of the group's technology. It will use a highly advance robotic arm to detect and uncover mines. The arm includes 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 much 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.

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