A ROBOTIC salamander crawls towards the water, steps in and starts swimming. It is a taster of what鈥檚 to come: a fresh breed of robots that will be able to switch seamlessly between swimming and walking, all under the control of an artificial nervous system.
In animals, movement is coordinated by a cluster of neurons in the spinal cord called the central pattern generator (CPG). This produces signals that drive muscles to contract rhythmically in a way that produces running or walking, depending on the pattern of pulses. A simple signal from the brain instructs the CPG to switch between different modes, such as going from a standstill to walking.
Now a team led by Auke Ijspeert at the Swiss Federal Institute of Technology in Lausanne has built an 85-centimetre-long 鈥渟alamander鈥� robot controlled by an artificial spinal cord and CPG. The CPG is a chip programmed to produce a pattern of electrical signals that instruct motors to control the movement of the robo-amphibian鈥檚 body segments and four legs. The timing of movements determines whether it is in swimming or walking mode.
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During tests in Lake Geneva, the robot switched between swimming and walking when it hit land (Science, vol 315, p 1416). As yet, the device lacks sensors to tell it whether it is on land or water, so someone has to tell the CPG to change the pattern it produces, using a remote control. 鈥淭he signals that we鈥檙e sending wirelessly are very similar to signals that the upper part of the brain sends to the spinal cord in animals,鈥� Ijspeert says.
