Engineers Mark Cutkosky and David Lentink, who worked in the labs of Stanford University before moving to the University of Groningen in the Netherlands, have developed a bird-like robot that can perch and carry objects.
William Roderick, PhD, was a graduate student in both of the labs.
“It’s not easy to mimic how birds fly and perch,” Roderick said. “After millions of years of evolution, they make takeoff and landing look so easy, even among all of the complexity and variability of the tree branches you would find in a forest.”
The researchers have been studying animal-inspired robots and bird-inspired aerial robots for years, and this has led to the development of the new perching robot.
The robot was detailed in a paper published on December 1 in Science Robotics.
The device is called a “stereotyped nature-inspired aerial grasper,” or SNAG. When it is attached to a quadcopter drone, the result is a robot that can fly around, perch on different surfaces, and catch and carry objects. The researchers used the robot to compare different types of bird toe arrangements and to measure microclimates in the Oregon forest.
Previous Studies With Parrotlets
The team’s previous studies with birds involved parrotlets, which are the second smallest parrot species. The birds were recorded by high-speed cameras as they flew back and forth between special perches, which were represented in different sizes and materials. These perches contained sensors that captured the physical forces associated with the birds as they took off, landed, and perched.
Roderick is lead author of the paper.
“What surprised us was that they did the same aerial maneuvers, no matter what surfaces they were landing on,” said Roderick. “They let the feet handle the variability and complexity of the surface texture itself.” This formulaic behavior seen in every bird landing is why the “S” in SNAG stands for “stereotyped.”
Structure of SNAG
SNAG is similar to the parrotlets in how it approaches every landing in the same way. However, due to the size of the quadcopter, SNAG is based on the legs of a peregrine falcon. Instead of bones, it possesses a 3D-printed structure, and it has motors and fishing line as muscles and tendons.
Each leg of the robot has its own motor that moves it back and forth, as well an additional one for grasping. A mechanism in the robot’s leg helps it absorb landing impact energy, which is then passively converted into grasping force. This helps create a strong and high-speed clutch that can be triggered to close in as little as 20 milliseconds. SNAG’s ankles lock once it wraps around a branch, and an accelerometer that is located on the right foot reports when it has landed, triggering a balancing algorithm for stabilization.
There are many potential applications for a robot like SNAG, such as search and rescue missions and wildfire monitoring. It can also be attached to technologies other than drones and be placed alongside birds to gain insight into avian biology.
According to Roderick, one of the most promising and exciting potential applications is environmental research. The team attached a temperature and humidity sensor to the robot before using it to record the microclimate in Oregon.
“Part of the underlying motivation of this work was to create tools that we can use to study the natural world,” said Roderick. “If we could have a robot that could act like a bird, that could unlock completely new ways of studying the environment.”
The new SNAG robot will undoubtedly play a role in improving our environmental research, providing new insights that were previously out-of-reach.