Birds take off and land on a wide range of complex surfaces, while current robots are limited in their ability to grasp irregular objects according to the opening paragraph of a new research paper. It is not easy to mimic how birds fly and perch, according to William Roderick, a roboticist at Stanford University and a co-author of the study.
Mark Cutkosky and David Lentink worked with Roderick to build a perching robot. The team designed, built, and tested a biomimetic robot that can perch on complex surfaces and grasp irregular objects.
The new contraption is called SNAG, which stands forstereotyped nature-inspired aerial grasper. The engineers are referring to the behavior involved in bird landings. Birds use the same grasping technique regardless of the surface. The feet of birds can handle the variability and complexity of the surface texture.
The legs and feet of the robot were modeled after those of falcons. It can carry 10 times its own weight. The bot is made from plastic and fishing line, and its muscles and tendons are made from motor and fishing line. Each leg has its own motor that can allow for 14 degrees of freedom. The engineers write that the robot can be balanced on its legs by rotating the center of mass toward the center of the perch like a bird.
The legs absorb impact energy and convert it into grasping force. The action happens in less than 50 milliseconds. Once the claws have grasped onto the branch, the anklet lock and an accelerometer will sense the landing and send a balancing algorithm for stabilization. The timing of the triggering was important. Birds and other animals may benefit from the timing of leg muscles and tendon tension being equal in importance.
In a forested environment, controlled testing of SNAG was conducted. The robot was launched at different speeds and orientations. The cornhole bag and tennis ball were caught by SNAG.
A future version of SNAG could do environmental research. The motivation for this work was to create tools that we can use to study the natural world. If we could have a robot that could act like a bird, that would open up completely new ways of studying the environment. The aerial robot measured microclimates in a remote Oregon forest using temperature and humidity sensors.
It has already done a bit of this, and SNAG could offer new insights into biology. The engineers learned that the arrangement of toes doesn't matter when it comes to perching performance. The study suggests that perching does not form an evolutionary selection pressure that can explain arboreal avian toe diversity.
With SNAG sticking its landings with ease, the team is now looking ahead to improving pre-landing elements like situational awareness and flight control. We are looking forward to seeing where the engineers take this project.
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