Hungry hungry robots

NO PLUGS: The EcoBot has been designed to power itself by 'eating' dead flies or waste water.

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When you think of robots becoming more like us, you tend to think of examples like C3PO from Star Wars or Honda's ASIMO, machines that look and behave a lot like us on the outside, even though their insides are full of motors and wires instead of flesh and blood. But there is a class of robots that looks nothing like us from without but within mimics one of our most crucial functions: They eat and digest food.

A key motivation for the development of these machines, which are still very primitive, is that in many places where robots operate there aren't any three- point plugs around. And sometimes there isn't even sunlight, for example underground or deep underwater. Such isolated places are often inhospitable to humans, so it makes sense to use robots in these situations, but the very lack of humans also means there is a lack of electricity for the robots to run on.

There is another way, though, and that is to find food from the environment and digest it to generate energy. The EcoBot-III, created by a group led by Ioannis Ieropoulos, of the Bristol Robotics Laboratory in England, is designed to survive by "eating" dead flies or waste water, though a more varied diet is possible.

The digestive system of the EcoBot-III superficially resembles our own. It takes in food and water through a kind of mouth, breaks it down in a stomach and ejects the waste once a day as a solid pellet. But the guts of the EcoBot-III are really quite different from our own.

While the goal of human digestion is to extract sugars and other nutrients that can be used later by the body, the goal of robot digestion is to generate electricity directly. This is done using a microbial fuel cell (MFC) which the team have developed. An MFC harnesses the electrical activity of microbes as they feed on the organic mix coming from the stomach. The electricity produced - quite miniscule at present - is collected by the MFC and used to charge the robot. It's very early days but one day MFCs may make a practical power source for robots.

In 2010, EcoBot-III operated for seven days straight in a specially constructed environment where it had to move around to collect food and water. The experiment was ended by a mechanical failure but it clearly demonstrated the viability of digesting robots.

There is a lot of work to be done and this is very new territory. Robotics is already a complicated business and digestion adds a whole slew of biological problems to the picture. Not only do you have to worry about software bugs, but stomach bugs as well. If digesting robots do become practical we aren't likely to see them - after all they are intended to work mainly in places where humans are not around much. Behind the scenes, though, they could be very handy.

It's food for thought, anyway.

- © Fairfax NZ News