It’s not particularly difficult to make a robot that looks like an animal. It’s much harder to make a robot that behaves like an animal. At EPFL, a group led by Prof. Auke Jan Ijspeert has been working on swimming robots for over a decade, using the salamander as a model, and Pleurobot looks like the most accurate—and eerily lifelike—yet.
Alllllright, so the whole talking thing is maybe not typical behavior for salamanders, but we’ll let it slide. The key to Pleurobot’s lifelike motion is its design, which was based on 3D x-ray movies of a real salamander walking and swimming:
Tracking up to 64 points on the animal’s skeleton we were able to record three-dimensional movements of bones in great detail. Using optimization on all the recorded postures for the three gaits we deduced the number and position of active and passive joints needed for the robot to reproduce the animal movements in reasonable accuracy in three-dimensions.
By design Pleurobot provides torque control for all the active joints, which enables us to apply our neural network models of the spinal cord neural circuits (called Central Pattern Generators) of the salamander and to activate virtual muscles to replicate the recorded animal movements along with realistic viscoelastic properties. This is particularly important in order to get a fundamental understanding of vertebrate motor control.
In other words, the joints and muscles of the robotic salamander respond in just the same way that the joints and muscles of a real salamander do. This means that applying neural patterns that real salamanders use for walking to the robot salamander will (or should, at least) cause the robot to walk in the same way. And it seems to work rather well.
Pleurobot may not be the fastest of walkers, but its low center of gravity makes it exceptionally stable, and it’s also multimodal: it can walk on land, swim under water, and transition seamlessly between the two. This makes it ideal for the obligatory search-and-rescue applications, although for aquatic operations the robot needs to wear a waterproof swimsuit, as you can see at the end of this vid from NCCR:
So what’s next? This is what’s next: “In the future, we plan to use Pleurobot’s design methodology to bring early tetrapods to ‘life.’ ” Yup: EPFL is bringing on the robotic dinos.
Evan Ackerman is a senior editor at IEEE Spectrum. Since 2007, he has written over 6,000 articles on robotics and technology. He has a degree in Martian geology and is excellent at playing bagpipes.