Abstract
There is a growing interest in unmanned aerial vehicles (UAVs) grasping, perching, and interacting with their surroundings by means of claws, arms, hooks, and other appendages. While multirotor vehicles can slowly lower onto a target object and grasp it, winged UAVs require a minimum speed to remain airborne and cannot hover. In this article, we describe a novel avian-inspired grasping mechanism that allows winged UAVs to grasp an object while flying over it. We have developed a high-speed, passively triggered claw that can close in under half a second. We characterize the loads encountered by the vehicle during the grasp event and find that grasping an object of about 30 g produces a maximum load of less than 12 N. Numerical experiments indicate that these loads cause a change in pitch of less than 1 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> and a decrease in speed of about 0.3 m/s for a fixed-wing vehicle of about 1 kg, and are thus negligible. We demonstrate outdoor in-flight grasping at 8 m/s, the fastest recorded grasping by a flying robot to date to best of our knowledge.
Highlights
T HERE are some spectacular videos of raptors rapidly swooping out of the sky to grasp prey midflight, both on land and from the water [1], [2]
In the field of aerial robotics, a very different strategy, which was designed for the ubiquitous rotary-wing platforms, is used to pick up objects
We study the mechanics of implementing object grasping on fixed-wing unmanned aerial vehicles (UAVs) through the use of a swooping strategy inspired by birds of prey
Summary
T HERE are some spectacular videos of raptors rapidly swooping out of the sky to grasp prey midflight, both on land and from the water [1], [2]. Unmanned aerial vehicles (UAVs) approach their target, come to a stop, lower themselves to the target, and grasp the object of interest [3]–[5] This strategy, is not suitable for more efficient winged UAVs, which are generally. We study the mechanics of implementing object grasping on fixed-wing UAVs through the use of a swooping strategy inspired by birds of prey (see Fig. 1). We conduct flight tests with the claw integrated in a winged aircraft and perform a swooping maneuver at high speeds (∼8 m/s) to grasp a 34-g object. The main contributions of this article are the following: 1) A novel passive claw concept for implementing the raptor inspired swooping strategy for fixed-wing UAVs. 2) Characterization of forces during a grasp with the swooping strategy. The main contributions of this article are the following: 1) A novel passive claw concept for implementing the raptor inspired swooping strategy for fixed-wing UAVs. 2) Characterization of forces during a grasp with the swooping strategy. 3) Experimental validation of our claw prototype and swooping strategy in a realistic environment
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