HEDGEHOG: Drone Perching on Tree Branches With High-Friction Origami Spines

The collection of environmental and biodiversity data is essential to manage, preserve and restore forests, but this task remains challenging due to the inaccessibility of these ecosystems. Compared to human intervention, aerial robots can access tree canopies, but their limited flight time and noise continue to stall widespread application. To address this challenge, we present a perching mechanism which allows small drones to rest on overhanging branches and extend their mission while remaining silent. We developed an origami spine with two folding flaps containing a layer of high-friction material. When the spine engages with a branch, the flaps open and conform to irregular branch surfaces generating sufficient friction to support the weight of a drone. With HEDGEHOG, a drone integrating multiple spines on a protective cage, we demonstrated its application in a controlled indoor as well as in a forest environment. We modelled the perching strategy and measured the effects of materials and geometric parameters on the drone's perching performance. By leveraging interactions with nature, our drone can perch on tree branches with diameters up to 86 mm and inclined up to $\pm$ 15$^\circ$ and potentially remain in the canopy for extended periods of time to acquire data or monitor returning wildlife.