This bio-inspired robot may be the future of search-and-rescue missions.
Bio-inspired robotic locomotion is a fairly new sub-category of bio-inspired design, revolving around learning concepts from nature and applying them to the design of real world engineered systems. More specifically, this field is about making robots that are inspired by biological systems. When it comes to these bio-mimicking bots, it seems as though we’ve seen just about everything, ranging from bats to spiders to dogs. And while it may not be all that difficult to make a bot that looks like an animal, having it behave like one is an entirely different story.
Meet Pleurobot. Recently developed by the BioRob at EPFL and NCCR Robotics, it is a salamander-inspired robot that is truly amphibious, meaning it is capable of walking, changing its gait to navigate uneven terrain, and even swimming. As the researchers note, the key to Pleurobot’s eerily-lifelike motion is its unique design, which was based on 3D X-ray movies of a real salamander walking, waddling and swimming. By tracking up to 64 points on the animal’s skeleton, the team was able to record movements of bones, and then deduce the number and position of active and passive joints needed for the robot to reproduce the 3D movements with reasonable accuracy.
According to its research proposal, the team first created a snake robot Kulko with tactile sensors in order to test the suggested control framework. This was comprised of a serial connection of 10 identical ball-shaped joint modules, along with a smooth surface to avoid getting stuck against obstacles. Each of the joint modules had 2-degrees of freedom (pitch and yaw), and had used servo motors as its actuators. On each side of every joint module, there were four force sensing resistors tasked with measuring contact forces — these were the only contact points between outer shell and inner structure.
“The current layout of the sensors can only measure horizontal forces which is enough for the application. The total force is estimated by summing forces measured by each FSR on the module. Each module also contains two Lithium-Ion batteries, angle sensors (magnetic rotary encoders), voltage regulation card, battery charger card and microcontroller card. The microcontroller card is based on the Atmel microcontroller AT90CAN128 and is continuously measuring position of the motors and controlling them with a PWM signal. Modules communicate with each other over CAN bus,” BioRob’s Tomislav Horvat writes.
By design, Pleurobot provides torque control for all the active joints, which enabled its creators to apply their neural network models of the spinal cord neural circuits of the salamander and to activate virtual muscles to replicate the recorded animal movements along with realistic viscoelastic properties. This was imperative when obtaining a fundamental understanding of vertebrate motor control.
What’s more, Pleurobot is also waterproof. While this feature actually proved to be the project’s most daunting assignment, the salamander-like project is currently using a water-repellant skin suit. Moving forward, the team hopes to improve upon this layer with aspirations that one day, the bio-mimicking robot will have a role in search-and-rescue efforts, with shallow waters for example. Its amphibious nature will enable it to go where humans cannot.
In the future, the team says it plans to use Pleurobot’s design methodology to bring early tetrapods to ‘life.’ So sure, we can write about it all day, but watching it in action is so much better! Those wishing to read up on the bio-mimicking project can download the team’s detailed proposal here, or head over to its official page for an abbreviated version.