June 2016

EPFL Logo QUADRIIt’s no secret that we often steal the magic of nature for our own purposes, whether that’s literally in taking animals for their fur and other parts, often tragically, or in gently observing how they move and survive on a daily basis to come up with countless inventions we are able to call our own, generally with credit being given to the other deserving, fascinating creatures that walk (and swim) on Earth beside us. Biomimicry often plays a role in the 3D printing and robotics realm too and we’ve seen everything from butterfly wings inspiring more streamlined 3D printed structures for electronics toteams of bot spiders working together to complete projects, and more.

Now, researchers at The Swiss Federal Institute of Technology (EPFL) at Lausanne have gone to great lengths to study the Pleurodeles waltl, also known as the Spanish ribbed newt, and they have actually created a complex 3D printed robot which allows them to examine the amphibian closely. The hope is for part of a more noble cause in that with this research they will be able to translate some of this knowledge into helping paraplegic patients and amputees with creating improved neuroprosthetic devices—an area where both 3D printing and robotics have been heavily integrated of late.


Spanish ribbed newts

Preferring to generally hang out in calm, deep areas of fresh water, this particular salamander enjoys preying on other tiny inhabitants like tadpoles, able to take his desired menu items by injecting him with a poison that is highly toxic (while only offering minor irritation to a human). They derive their name from their famous ribs that are so sharp they actually poke out of the body, delivering toxins. Although they can walk on land, they generally do not. This particular newt, however, caught the attention of the EPFL researchers because of both his amphibious nature and his skeletal structure, the main area where their interests lie in helping those with conditions most likely caused by injuries to that corresponding area in the human body.

Studies at the EPFL regarding salamanders have been ongoing previously but this will be the first time that they’ve used 3D tracking (like X-Ray videos) to understand exactly how the amphibian moves, noting 64 different points along its skeleton. Dubbed Pleurobot, the machine can walk, crawl, and swim. His ‘bones’ are 3D printed, complemented by motorized joints and a complete electronic circuitry that serves as his nervous system. And while his action (see video below) might still be considered a bit lumbering, the researchers are able to learn a great deal from Pleurobot’s motion and spine working together. This has been a work in progress, however.

oneThe team recently released details of their project in a paper, ‘From cineradiography to biorobots: an approach for designing robots to emulate and study animal locomotion,’ by K. Karakasiliotis, R. Thandiackal, K. Melo, T. Horvat, N. K. Mahabadi, S. Tsitkov, J. M. Cabelguen, and A. J. Ijspeert—published in Journal of the Royal Society Interface. Here, they discuss the challenges in creating robots specifically to study animal locomotion.

“Our previous robots helped us test and confirm hypotheses on the interaction between the locomotor neuronal networks of the limbs and the spine to generate basic swimming and walking gaits,” said the researchers in their paper. “With Pleurobot, we demonstrate a design process that will enable studies of richer motor skills in salamanders. In particular, we are interested in how these richer motor skills can be obtained by extending our spinal cord models with the addition of more descending pathways and more detailed limb central pattern generator networks.”

They’ve obviously refined both their study of the salamander’s anatomy and robotics to that end as they contend that this model comes extremely close to replicating the movement of a real salamander, able to move as it would, and most importantly, from the limb area.

“The robot closely matches the behavior of the animal in terms of relative forward speeds and lateral displacements. Ground reaction forces during walking also resemble those of the animal,” state the researchers in their paper.


The researchers involved here obviously find great value in this particular skeletal system as they’ve continued to refine their tools for further study. With the Pleurobot, they made much greater progress using 3D technology to better imitate the gait. And while it’s still a challenging undertaking, with 27 motors integrated into the robot, they have a much better advantage this time. According to the team, they found that with employing a greater degree of minimalism they were more successful.

“What is new is really our approach to building Pleurobot,” says Ijspeert. “It involves striking a balance between designing a simplified bone structure and replicating the salamander’s gait in three dimensions.”

In looking closely at the design, the Pleurobot definitely looks a bit like a cross between a giant skeleton and a fish. The movement does look very authentic—enough so to make some of us a bit squeamish even! Equipped with internal positional sensors, it can cover rough terrain, and is also equipped with a camera and video feed. And while wearing a special dry suit, it also swims.

“Animal locomotion is an inherently complex process,” says Kostas Karakasilliotis, who designed the early iterations of the Pleurobot. “Modern tools like cineradiography, 3D printing, and fast computing help us draw closer and closer to understanding and replicating it.”


All involved in the project seem very pleased with their recent results and progression in the study. They expect that due to the Pleurobot’s advanced design, others endeavoring to study the rich motor skills of salamanders will greatly appreciate the design, as well as benefiting from it. While most of us may not have ever considered this before, there is actually a vast amount to be learned from this simple skeletal structure along with such a wide range of movement. As one of our earliest ancestors, the salamander may be primitive indeed, but it offers up a great deal of data in regards to walking and swimming and how the spinal cord is stimulated to respond. Discuss this amazing technology further in the 3D Printed Salamander forum over at 3DPB.com.

[Sources/Images: EPFL]




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