Here's something you don't see everyday: a Micro Unmanned Aerial vehicle (MAV) that can grab objects on the fly with all the elegance of an eagle snatching a fish from the water's surface. Although MAVs and UAVs are increasingly being equipped to pick up, transport, and drop off payloads, we've never seen this incredibly precise form of grasping on the fly replicated – until now.
The similarity to an eagle's hunting ability is no coincidence – University of Pennsylvania research team members Justin Thomas, Joe Polin, Koushil Sreenath and Vijay Kumar, programmed the quadrotor MAV based on observations garnered from nature videos. They found that the bird of prey dramatically reduces the velocity of its claws in relation to its prey by sweeping its legs back at the point of impact, allowing it to grasp its intended target without slowing down. Since they're working with an MAV weighing just 500 grams, they had to design and fabricate an appropriately light weight arm and gripper.
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Their solution is a arm weighing just 158 grams that attaches to a servo-driven swing to replicate the sweeping motion in their robot. To keep the weight down, they engineered a clever three-fingered claw that can naturally conform to different shapes but clenches and releases with just a single servo. These parts were then fabricated using a combination of 3D printing and laser-cut ABS and then covered with Dycem, which is a type of high-friction rubber that improves the robot's grip.
Besides looking damned impressive, they suggest that this sort of ability could be used in life or death situations where timing is everything. In a paper due to be presented at the International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE 2013), the team writes that this ability could be "extended to achieve perching capabilities, which could be used to quickly escape high winds, achieve immediate silence in stealth operations, and improve mission duration by reducing hover time."
It seems the MAV's next trick will be clinging to a wire mid-flight, and thanks to its adaptive grippers it could also perch in tree branches (and other places). For now we can enjoy watching it grab a light cylinder (27 g) at up to three meters per second in the following video.