[ASC-media] Media release: Ants show robots the way

JCA Media jcamedia at starclass.com.au
Sun Aug 22 22:28:27 EST 2004

Sir Mark Oliphant Conferences 2004 Media Release


A tiny desert ant which successfully navigates its way across hundreds of metres of featureless saltpans is teaching robots how to find their way.

For over three decades Zurich University's Professor Ruediger Wehner has grappled with the question of how so tiny an insect, with a brain weighing just 1/10th of a milligram, can perform the complex mathematical task of navigation.

Somehow, it seemed, the ant must have a compass for telling direction, an odometer for gauging distance, a means of integrating the two and storing all the information. But, the trouble is, there isn't room in its minute brain to do it all.

Like bees, Prof. Wehner's Cataglyphis ants use polarized light from the sky - caused when air molecules scatter sunlight and undetectable to humans - to orient and steer by. The ant has a set of specialized photoreceptors to pick this up. This was shown, for example, by equipping ants with special contact lenses that screened out polarised light, causing them to become lost!

However, as the sun moves, the ant has to note the sun's direction each time it leaves the nest - and update its compass.

It also stores a 'snapshot' image of landmarks close to the pin-hole sized nest entrance in its eyes and compares what it sees with the image as it re-traces its steps. Again, tiny contact lenses were used to test and confuse the ants.

The ant also has a way of measuring distance traveled, and a 'path integrator' which periodically informs the ant of its current position relative to its point of departure and vectors it back.

If, however, it loses both landmarks and vectors, the ant falls back on a simple search plan, Prof. Wehner says, going in widening loops until it locates what it recognises.

 "The ant uses simple tricks adapted to its needs - and these work perfectly well within its behavioural framework and ecological setting," he says.

Rather than integrate all the information it receives in its brain, the ant actually performs a number of complex calculations in other organs, such as the eyes. Like a supercomputer, this makes the ant "massively parallel" - with a lot of separate subroutines going on at the same time. All this it does without forming what we would call 'a map'.

Using the ant's ability to steer by polarized light and to store and re-use landscape images Prof. Wehner has co-operated with a team from the Zurich University Institute of Informatics and designed Sahabot, a small vehicle that uses polarizers and a digital CCD camera to store 360-degree images of its surroundings. It navigates by using polarized sky light and by comparing the current images of landmarks to the ones in its memory.

The Sir Mark Oliphant Conference on Insect Sensors and Robotics is being held at Emanuel College, the University of Queensland, in Brisbane, from August 23-25, 2004.

Media are welcome to attend and interview participants.

More information:
Prof. Ruediger Wehner, University of Zurich
ph + 61 (0)7 3871 9100
Professor M. Srinivasan, Australian National University, 0410 417 685
M.Srinivasan at anu.edu.au

Information on the conference:
Prof Julian Cribb, media contact, ph 0418 639 245

August 23, 2004

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