October 28, 2021

Squirrel Leaps Might Assist Scientists Create Versatile, Leaping Robots

6 min read

By Lucia F. Jacobs, Nathaniel Hunt and Robert J. Full

Tree squirrels are the Olympic divers of the rodent world, leaping gracefully amongst branches and buildings excessive above the bottom. And as with human divers, a squirrelโ€™s success on this competitors requires each bodily power and psychological adaptability.

The Jacobs lab research cognition in free-ranging fox squirrels on the Berkeley campus. Two species โ€“ the jap grey squirrel (Sciurus carolinensis) and the fox squirrel (Sciurus niger) โ€“ thrive on campus landscapes and are keen members in our behavioral experiments. They’re additionally masters in two- and three-dimensional spatial orientation โ€“ utilizing sensory cues to maneuver by way of area.

In a newly published study, we present that squirrels leap and land with out falling by making trade-offs between the space they need to cowl and the springiness of their takeoff perch. This analysis gives new insights into the roles of decision-making, studying and habits in difficult environments that we’re sharing with researchers of human motion and with engineers. At current, there’s no robot as agile as a squirrel, and none that may study or make choices about dynamic duties in advanced environments โ€“ however our analysis suggests the sorts of skills that such robots would wish.

Fox squirrel in eucalyptus grove on the campus of the College of California, Berkeley.

Judy Jinn, CC BY-ND

Whereas a squirrelโ€™s life could look easy to human observers โ€“ climb, eat, sleep, repeat โ€“ it entails finely tuned cognitive abilities. Squirrels are specialised seed dispersers: They harvest their winterโ€™s provide of nuts and acorns throughout a six- to eight-week span within the fall, bury every nut individually and rely on spatial memory to retrieve them, generally months later.

We all know that squirrels manage their caches hierarchically. When supplied with 5 nut species in a random order, Berkeley fox squirrels buried nuts in clusters according to species. As a result of bigger nuts comprise extra energy, squirrels make investments extra closely in them, carrying them to safer areas and spacing their hiding places farther apart.

We additionally found {that a} squirrel assesses the worth of a nut by flicking its head with the nut in its mouth, simply as a human may bob a pencil in her hand to evaluate its weight. And we all know that they create their cache maps based mostly on elements that embody the shortage of meals in that season, the amount of nuts already cached and the chance of being observed caching by other squirrels.

Grey squirrel rummaging by way of its nut cache in late fall.

Mark Gunn/Flickr, CC BY

Together with observational research, we’ve got additionally assessed how squirrels carry out summary spatial duties. For instance, we’ve got measured how properly they can inhibit a lunge toward a remembered food location โ€“ a part of a world research on the evolution of self management. In one other experiment, we put squirrels by way of a vertical maze that mimicked the branching choices they face when navigating in bushes to see how they return to locations that they remember.

We even have discovered that whereas squirrels have been fixing a tabletop reminiscence puzzle, their cognitive flexibility peaked throughout the intense interval of storing their winter meals provide. This explains why Berkeley squirrels are able to switch more easily between types of landmarks throughout the caching season.

Our new research introduced collectively squirrel psychologists and comparative biomechanists to ask whether or not squirrelsโ€™ cognitive decision-making extends to dynamic adjustments in locomotion โ€“ the well-known squirrel leap. How do squirrelsโ€™ perceived capabilities of their our bodies and their guesses concerning the stability of the atmosphere form their choices about motion?

Robert Full from the PolyPEDAL Laboratory is famend for research that extract elementary design ideas by way of experiments on locomotion in species with distinctive specializations for motion, from crabs to cockroaches to leaping lizards. Graduate college students Nathaniel Hunt, who’s skilled in biomechanics, and Judy Jinn, skilled in animal cognition, took on the problem of assessing how a leaping squirrel might reply to sudden adjustments within the location and suppleness of experimental branches.

To review this query in wild squirrels, we designed a magnetic climbing wall that might be mounted on wheels and rolled out to the well-known Berkeley eucalyptus grove to satisfy the squirrels on their very own turf. We introduced high-speed cameras and peanuts for persuading squirrels to patiently wait for his or her activate the wall.

Our purpose was to influence squirrels to take off from a versatile springboard hooked up to the climbing wall and leap to a set perch protruding from the wall that held a shelled walnut reward. And as soon as once more, squirrels shocked us with their acrobatics and innovation.

By growing the springiness of the springboard and the space between it and the purpose, we might simulate the problem a squirrel faces because it races by way of tree branches that adjust in measurement, form and suppleness. Squirrels leaping throughout a spot should determine the place to take off based mostly on a trade-off between department flexibility and the scale of the hole.

We discovered that squirrels ran farther alongside a stiff department, so they’d a shorter, simpler leap. In distinction, they took off with only a few steps from versatile branches, risking an extended leap.

Utilizing three branches differing in flexibility, we guessed the place of their takeoff by assuming equal danger for leaping from an unstable department and leap distance. We have been unsuitable: Our mannequin confirmed that squirrels cared six occasions extra a couple of secure takeoff place than how far they needed to leap.

Subsequent we had squirrels leap from a really stiff platform. Unbeknownst to the squirrels, we then substituted an identical-looking platform that was thrice extra versatile. From our high-speed video, we calculated how far-off the middle of the squirrelโ€™s physique was from the touchdown perch. This allowed us to to find out the touchdown error โ€“ how far the middle of the squirrelโ€™s physique landed from the purpose perch. Squirrels shortly realized to leap from the very flexible department that they anticipated to be stiff and will stick the touchdown in simply 5 tries.

After we raised the ante nonetheless additional by elevating the peak and growing the space to the purpose perch, the squirrels shocked us. They immediately adopted a novel answer: parkour, actually bouncing off the climbing wall to regulate their velocity and achieve a sleek touchdown. As soon as extra, we found the outstanding agility that enables squirrels to evade predators in considered one of natureโ€™s most difficult environments, the tree cover.

Hundreds of thousands of individuals have watched squirrels remedy and raid โ€œsquirrel-proofโ€ chook feeders, both stay of their yard or in documentaries and viral videos. Like Olympic divers, squirrels have to be versatile each bodily and cognitively to succeed, making fast error corrections on the fly and innovating new strikes.

With the funding this mission attracted, we’ve got joined a group of roboticists, neuroscientists, materials scientists and mathematicians to extract design ideas from squirrel leaps and landings. Our group is even on the lookout for insights into mind perform by learning leap planning in lab rats.

Our evaluation of squirrelsโ€™ outstanding feats might help us perceive learn how to assist people who’ve strolling or greedy impairments. Furthermore, with our interdisciplinary group of biologists and engineers, we try to create new supplies for essentially the most clever, agile robotic ever constructed โ€“ one that may help in search-and-rescue efforts and quickly detect catastrophic environmental hazards, akin to poisonous chemical releases.

A future imaginative and prescient for our efforts? First-responder robotic squirrels, outfitted with the bodily and cognitive toughness and suppleness of a squirrel at a chook feeder.

Judy Jinn, who participated on this research as a graduate scholar, is a quantitative UX Researcher at Fb.

Lucia F. Jacobs is a Professor of Psychology on the College of California, Berkeley Nathaniel Hunt is an Assistant Professor of Biomechanics on the College of Nebraska Omaha and Robert J. Full is a Professor of Integrative Biology at College of California, Berkeley.

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