Professor Kumar Ramohalli of the University of Arizona: Robots based on animals and humans

A prototype of the machine - called a Birod (Biomorphic Robot with Distributed power) - has been built at the University of Arizona.

It moves using wires and springs which contract like muscles when electricity is passed through them.

The Birods would be able to move across terrain restrictive to wheeled robots, and carry up to 17,000 times their own weight.

Four legs good

The prototype is a box supported by two legs with stabilising wheels at the back. The working models, however, would have four legs to enable them to step over obstacles.

Professor Kumar Ramohalli, head of the Birod programme, said: "We are trying to imitate biological systems.

"Birods are much simpler than robots you have seen in the past."

The lack of complex machinery makes the Birod light and reliable - ideal for space missions. They are also less likely to have their workings damaged by dust, and take up less space and payload weight on spacecraft.

Cat-like machine

Prof Ramohalli said: "Everything doesn't depend on central control, so if one leg stops working everything doesn't jam up and freeze. Birods can limp along on the other legs."

The Birod would be able to take "cat naps", the professor said, able to rest and regain energy before springing to life when action was called for.