There is a robot that can jump on water like an insect, one that can run like a dog, and now there’s one that can sense its environment like a seal. Scientists from the University of Illinois have developed a robot that mimics how the pinnipeds' whiskers work, and builds up a 2D image of the environment by analyzing air currents as they pass over them.
Many mammals use whiskers as their main sensory system to explore their surroundings. “When it is dark, whiskers play a key role for animals in exploring, hunting or even just living underground,” explains Cagdas Tuna, who coauthored the paper that describes the robo-whiskers, published in Bioinspiration and Biomimetics. “For example, seals can catch fish in the dark by following the hydrodynamic wake using their whiskers.”
Researchers have already built robotic whiskers that copy the ability of rats to sense the environment through touch, which were shown to be able to identify 3D objects, determine their texture and assist navigation. But the new study decided to investigate the possibility of designing whiskers that could build up a picture of the environment in a similar way to how seals use the flow of water.
The whiskers mimic the way seals follow hydrodynamic wakes using their own. CC 0 from Pixabay.
Because air is technically a fluid, it behaves in generally the same way as water in regard to how it flows. So rather than testing their new creation in the water, they decided to opt for the humble hair dryer to create a "fluid-flow" over the whiskers.
Using an array of strain gauges at the base of the “whiskers,” which were made out of super-elastic nitinol (nickel titanium) wires covered with plastic straws, they were then able to build up a tomographic map by measuring the air flow over them. This is a similar way to how MRI scanners build up 2D images of the human body. While the researchers admit that there is no way of knowing that animals create the images in their brain in the same way, it does show the potential of using this technique to “see” in difficult situations.
Not only were the robo-whiskers able to assess the direction and source of the flow of air, they were also able to track changes in the flow. The researchers think that this could have advantages as a sensory system used in murky or smoky environments, which currently have to rely on radar or sonar, often with poor resolution or blind spots. The potential applications of robotic whiskers don’t stop there.
“This may even find use in biomedical applications, such as cardiac surgery,” says Tuna. “A thin-whiskered catheter tip could be used during surgery to track the relative position inside the heart, potentially reducing the risk of injury, or atrial fibrillation.”