If you were choosing a fighter for competitive parkour, which animal would you select?
For the authors of a new study published in the journal Science, squirrels are the obvious choice. These nimble mammals are the focus of research exploring the split-second decisions that enable them to stick impossible landings in unpredictable terrain.
“Arboreal locomotion should be incredibly difficult for many reasons,” said co-author of the paper, assistant professor Nathanial Hunt, to IFLScience.
“Opportunities for foot placement may be very limited. Gaps in an animal’s path require leaping from flexible branches that bend in unpredictable ways. But despite these seemingly difficult challenges squirrels navigate the canopy rapidly and effortlessly."
"If we try to understand how squirrels do this can do this then we may discover general principles of high performance locomotion in the canopy and other complex terrains that apply to the movements of other animals and robots.”
While the concept of AI that can masterfully navigate the canopy at speed might seem a little Terminator, such innovations could be used to create robots capable of exploring natural disaster sites that can’t be safely accessed by humans, finding survivors or gathering data on environmental threats.
To find out how squirrels decide which leaps to take and correct dodgy landings, Hunt and colleagues lured in some wild fox squirrels and confronted them with an assault course that would reward them with peanuts. They found snack-seeking squirrels had a more considered approach when confronted with flimsier supporting “branches”, but their confidence and speed grew with practice.
“When they leap across a gap, they decide where to take off based on a tradeoff between branch flexibility and the size of the gap they must leap,” said Hunt. “And when they encounter a branch with novel mechanical properties, they learn to adjust their launching mechanics in just a few jumps."
"This behavioral flexibility that adapts to the mechanics and geometry of leaping and landing structures is important to accurately leaping across a gap to land on a small target.”
In terms of the weight given to different obstacle varieties, branch bendiness appeared more significant than gap distance. The researchers hypothesize that this could be due to the fact that squirrels are armed with impressive claws that can rescue even the most fumbled of leaps – provided they reach the target.
Where parkour really came into play was in the study’s discovery that during particularly tricky jumps, the squirrels could use vertical surfaces to push off of and reorient their bodies. This approach to environment navigation mirrors the human sport magnificently. So, could we soon be tuning in to Robokour?
“This kind of behavioral flexibility in robots is a huge challenge,” said Hunt. “But taking an interdisciplinary approach, including researchers in biomechanics, animal cognition, robotics, neuroscience, control, and metamaterials, will be important to discovering the crucial mechanisms.”
It seems, then, there is still quite a leap to robots dashing merrily through our treetops – but, as Hunt explains, plans are very much underway to fulfill the interdisciplinary approach needed to achieve this kind of locomotion in AI technologies.
“New experiments are investigating the biomechanics and control of leaping and landing and balance in squirrel including the roles of structures in the feet to attach and generate forces, traversing branches the extend in three-dimensional space, the neuromechanics of making locomotion decisions, and learning over their lifespan,” he said.
“And on the robotics side there are investigations into new legged robot designs and control, designing metamaterials that behave like spines, and modeling the balance of leaping and landing.”