IT IS often said there鈥檚 no point reinventing the wheel, but when it comes to getting rescue robots into and out of avalanches, that may be just what is needed. So say researchers in Japan who have developed an adjustable wheel that can adapt to different kinds of snow conditions.
Robots are increasingly used to locate survivors of disasters such as earthquakes, who can be trapped in places too risky for human rescuers. 鈥淏ut few are applicable to rescue in snow,鈥� says Taro Iwamoto at in Shiga, Japan. Even caterpillar treads can skid or sink in certain types of snow and ice.
Iwamoto鈥檚 team has built a wheel with six vanes on its side that are linked to both the wheel and a central hub (see diagram). The rear of each vane pivots on the wheel, while a spoke from the hub joins the vane nearer its centre. By varying the position of the hub relative to the wheel axle, the operator can alter the angle of the vanes, ensuring the best possible traction for the conditions and preventing the wheel from sinking or slipping.
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For example, on ice the vanes can be angled so that those underneath hook into the surface to gain traction, pulling the wheel forward. In soft snow, they can either lie flat to compact the snow or act as paddles to push the wheel along. The wheel can also transform into a digging device, allowing the robot to burrow into a wall of snow or simply clear a path. To prevent snow from clogging up the central space between the vanes, the hub control mechanism is housed in the wheel disc (, vol 21, p 216).
Noel Sharkey, a roboticist at the University of Sheffield, UK, says initial tests of the device on snow look promising. He thinks the vane mechanism should give it more traction than alternatives such as caterpillar tracks or skis. What鈥檚 more, robotic vehicles that use it should be able to carry larger payloads. 鈥淏ut I suspect they may be considerably slower,鈥� he says.
Indeed, the current prototype has a maximum speed of 20 centimetres a second, though Iwamoto says the team is designing a four-wheel-drive version that they think will be faster. 鈥淲e plan to test it this winter,鈥� Iwamoto says.
Robots capable of travelling in snow and ice could play an important role in locating and rescuing people from avalanches, alongside or in place of dogs and human rescuers. They could be especially useful where buildings have been buried, says Benjamin Zweisel of the in Davos. 鈥淚t鈥檚 not easy to get into buildings. Usually the snow is very compact after an avalanche.鈥�
鈥淩obots capable of travelling in snow and ice could help rescue people trapped in avalanches鈥�
