A hopping robot tries to match the agility of squirrels. Can it stick to the landings like nature’s parkour experts? Read more!
Engineers have built robots that crawl, swim, fly, and even slither like snakes, but none match a squirrel’s agility — effortlessly parkouring through branches, leaping across gaps, and landing precisely on the thinnest limbs. To change that, biologists and engineers at the University of California, Berkeley, studied how squirrels jump and land. Using their findings, they created a hopping robot capable of sticking landings on narrow perches.
Mixing biology and robotics
To explore whether squirrels used a similar technique, the biology and robotics teams conducted experiments together. The team attached sensors to a branch to measure the forces squirrels applied when landing, including the perpendicular force and the torque created by their feet. These insights helped improve Salto’s ability to stick its landings.
Using high-speed video and sensor data, the research team discovered that when squirrels land after a big leap, they perform a sort of handstand on the branch. This technique directs the landing force through their shoulder joint, minimizing stress on the joint. Then, using the pads on their feet, squirrels grip the branch and twist to counter any excess torque that might cause them to lose balance.
Future research could explore more advanced grippers to enhance the robot’s ability to control the torque it applies to a branch, improving its landing capabilities. Such advancements could also allow the robot to land on complex flat surfaces, not just branches.
Meanwhile, ongoing studies are examining how squirrels apply torque with their feet when landing. Unlike monkeys, which have opposable thumbs for a prehensile grip, squirrels rely on a palm-like grasp. This might actually be beneficial. A squirrel being pursued by a predator, like a hawk or another squirrel, needs a stable enough grip to quickly push off a branch without holding on too tightly. Their natural ability to bounce off branches without worrying about letting go enhances their agility.
While one-legged robots may seem unstable when standing, they offer advantages for jumping to great heights, making them a practical design for certain applications.
