UC Berkeley researchers have developed a squirrel-inspired robot that can leap and land with pinpoint accuracy. This innovation could lead to more agile robots for construction, environmental monitoring, and even space exploration.
Robots have crawled, swum, flown and even slithered, but none can quite match the acrobatic feats of a squirrel — until now. A team of biologists and engineers at the University of California, Berkeley, have developed a revolutionary one-legged robot inspired by the athletic prowess of squirrels, capable of jumping from branch to branch and executing precise landings.
This advancement, reported in the journal Science Robotics, marks a significant leap forward in robot agility and could have applications ranging from construction to space exploration.
“The robots we have now are OK, but how do you take it to the next level? How do you get robots to navigate a challenging environment in a disaster where you have pipes and beams and wires? Squirrels could do that, no problem. Robots can’t do that,” co-senior author Robert Full, a professor of integrative biology at UC Berkeley, said in a news release.
In a remarkable fusion of biology and engineering, the team aimed to replicate the astonishing maneuvers of squirrels, considered nature’s top athletes.
“Squirrels are nature’s best athletes,” Full added. “The way that they can maneuver and escape is unbelievable. The idea is to try to define the control strategies that give the animals a wide range of behavioral options to perform extraordinary feats and use that information to build more agile robots.”
The innovative robot, named Salto, was initially developed in 2016 and could already perform hops and parkour stunts, sticking landings on flat surfaces. However, translating these skills to uneven and narrow perches posed a new challenge.
Co-first author Justin Yim, a former UC Berkeley graduate student, drew inspiration from the control strategies observed in squirrels and adapted them to Salto.
“If you think about trying to jump to a point — maybe you’re doing something like playing hopscotch and you want to land your feet in a certain spot — you want to stick that landing and not take a step,” Yim, now an assistant professor of mechanical science and engineering at the University of Illinois, Urbana Champaign (UIUC), said in the news release. “If it feels like you’re falling backward and you might have to sit down because you’re not going to be able to quite make it, you might pinwheel your arms backward, but you’re likely also to crouch down as you do this.”
Yim utilized these insights, enabling Salto to adjust its body posture mid-air to achieve more accurate landings. These adjustments are akin to a gymnast’s mid-air corrections, making Salto’s feats even more impressive.
“Almost all of the energy — 86% of the kinetic energy — was absorbed by the front legs,” Yim added, highlighting the similarity between the robot’s new mechanics and a squirrel’s natural handstands on branches. “They’re really doing front handstands onto the branch, and then the rest of it follows. Then their feet generate a pull-up torque, if they’re going under; if they are going to go over the top — they’re overshooting, potentially — they generate a braking torque.”
Perhaps most exciting is the potential application of this robotic technology in extraterrestrial environments, such as NASA-funded explorations of Saturn’s moon Enceladus, where low gravity could allow the robot to cover significant distances with each leap.
The team continues to refine Salto, aiming to enhance its abilities with advanced gripping mechanisms.
“In future work, I think it would be interesting to explore other more capable grippers that could drastically expand the robot’s ability to control the torque it applies to the branch and expand its ability to land. Maybe not just on branches, but on complex flat ground, too,” added Yim.
Salto’s advanced leaping mechanics underscore a promising future where robots can navigate complex terrains with the finesse and agility of squirrels, opening new possibilities in construction, disaster response and even beyond our planet.
“If you’re a squirrel being chased by a predator, like a hawk or another squirrel, you want to have a sufficiently stable grasp, where you can parkour off a branch quickly, but not too firm a grasp,” Full added. “They don’t have to worry about letting go, they just bounce off.”
This innovative project demonstrates the high level of interdisciplinary and collaborative effort involved in bridging the gap between natural biology and robotics.