Swimming robot reveals evolutionary clues

Salamandra robotica takes a dip (EPFL Lausanne)

A robot designed by Swiss and French scientists is helping to explain how the first vertebrates emerged from water and onto land hundreds of millions of years ago.

This content was published on March 14, 2007 - 11:00

Inspired by a salamander, the robot is controlled by a system that imitates the amphibian's spinal cord, enabling it to alternate between swimming and walking.

Salamandra robotica, as the robot is called, has already been swimming in Lake Geneva and crawling along the lakeshore.

The robot does not look much like a salamander – it is 85cm long and made of nine bright yellow plastic segments each containing a battery and microcontroller – but it does seem to move like one.

According to team leader Auke Jan Ijspeert of the Federal Institute of Technology in Lausanne, the aim was to understand how a spinal cord developed for a swimming motion could handle the different coordination needed for walking.

"We picked the salamander because it is a key animal from an evolutionary point of view," Ijspeert told swissinfo.

"It is believed to be very close to the first vertebrate that made the transition from aquatic locomotion to terrestrial locomotion."

Nervous system

The team designed a basic nervous system modelled on that of the lamprey, a long, primitive eel-like fish. That design was then modified to show how it could evolve into a nervous system that also could control walking.

The robot's swimming motion uses undulating movements like the lamprey, while on land the robot uses a slow stepping gait with diagonally opposed limbs moving together while the body forms an S-shape.

Ijspeert said the research opened up a range of possibilities for future developments. These include search and rescue robots, help in understanding spinal cord injuries, and even possible spin-offs for the toy industry.

"The big challenge we faced was making it waterproof," he said. "We are now working on a third prototype which is a better swimmer."

The robot is powered by ten motors, has four rotating legs and six movable joints along its body. Simple electrical signals make it change its speed and gait.

Electrical signals similar to the signals sent from the upper brain to the spinal cord are transmitted from a laptop to the robot. They make the robot change its speed and direction, and change from walking to swimming.

swissinfo with agencies

Key facts

Scientists from the Federal Institute of Technology in Lausanne and the French National Institute for Health and Medical Research (Inserm) carried out the study.
The research was funded by the Swiss National Science Foundation and the French Ministry for Research and Technology.

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