Mechanical mole seeks out disaster survivors under collapsed buildings

Published 19 September 2007

Robots already roll, walk, slither, and even “swarm” to locate or help survivors, so why not dig and burrow? University of Manchester rsearchers build a digging robot which imitates the common European mole

A digging robot inspired by the humble, and rather ungainly, European mole is being built by U.K. researchers, who hope it could one day “swim” through rubble at disaster sites to help find survivors. Roboticists are already experimenting with robots which roll, walk, slither, and even “swarm” to locate or help survivors, so why not burrow? The New Scientist’s Kurt Kleiner writes that Robin Scott and Robert Richardson at the University of Manchester think a robot which digs would indeed be most useful in an emergency. The pair has already built a new digging mechanism that could shove aside relatively light objects, such as bricks or furniture. “What you find is that there is lots of debris that you can move, like ceiling tiles, tables, and chairs,” Richardson says. “Everything that’s in the building falls over, and most buildings tend to partially collapse. If you can’t interact with debris, you drive up and get stuck.”

The digging robot was inspired by the European mole, which uses its spade-like front paws in a digging motion similar to a swimmer’s breast-stroke.

The first part of the “stroke”’ drags earth in front of the animal to the side and pushes it to the rear. The return stroke brings the forelegs to the front again, keeping them close to the mole’s body to avoid pushing already-moved earth forward again. To duplicate this motion, the researchers used a tried-and-tested design called a four-bar mechanism. The mechanism is similar to the arrangement that drives car windscreen wipers. The new mole-style digging arm links two of these four-bar mechanisms. This arrangement makes it possible to create a mole-like digging motion from two normal rotary electric motors which never need to run in reverse. This should make for low maintenance, say the researchers. In tests, the digging arm has successfully moved aside bricks and other debris. The design is now being mounted onto a robot chassis for more comprehensive tests. Richardson says an actual search-and-rescue robot based on the design might be ready in two years.

Details of the mechanical mole mechanism will appear in a forthcoming edition of the ASME Journal of Mechanical Design.