EPFL's Pleurobot is, obviously, our favorite robot salamander. This is likely because it looks so much like a real salamander, but more importantly, it moves just like a real salamander. Or, to be more specific, EPFL has spent years trying to make sure that the way Pleurobot moves is as close to the way that a real salamander moves as possible. In a new paper just published in the Royal Society journal Interface, EPFL researchers describe how they've combined "high-speed cineradiography, optimization, dynamic scaling, three-dimensional printing, high-end servomotors, and a tailored dry-suit" to refine their robot to accurately capture the degrees of freedom, range of motion, and gait behaviors of the real animal. Primarily, it's because they're cute, but there are a variety of much less important considerations that make salamanders interesting to study as well.

The researchers designed Pleurobot with fewer bones and joints than the real-life creature. The robot features only 27 motors and 11 segments along its spine, while the amphibian has 40 vertebrae and multiple joints, some of which can even rotate freely and move side-to-side or up and down. In the design process, the researchers identified the minimum number of motorized segments required, as well as the optimal placement along the robot's body. As a result, it could replicate many of the salamander's types of movement. "Animal locomotion is an inherently complex process," says Kostas Karakasilliotis who designed the first versions of the Pleurobot.

Pleurobot is made up of 3D-printed bones, motorized joints and an electronic circuitry that serves as its synthetic central nervous system. It has fewer vertebrae than an actual salamander, but the scientists optimized their placement so that the machine's movements look as authentic and natural as possible. Team leader Auke Ijspeert says Pleurobot can help them understand vertebrate locomotion. You see, the lowest level of electrical stimulation in salamanders' spinal cords is associated with walking, while the highest is associated with swimming. As such, the machine can help scientists explore the relationship between spinal cord stimulation and a vertebrate animal's movements. In the future, this could lead to neuroprosthetic devices for both amputees and paraplegic patients.