TreeSpider: In‐Canopy Exploration With Tether‐Based Aerial Modular Arms

Aerial robots hold great promise for forest canopy research by enabling data collection at high spatial and temporal resolutions. However, navigating dense foliage remains a challenge due to limited maneuverability. We present a tether‐based drone with perching arms and anchoring capabilities for stable in‐canopy operation and manipulation. Once anchored to a branch, the system uses a 360° ring to decouple the tether from the drone frame, allowing free movement in all directions. The ring enables independent pitch control, and a dynamic tether system adjusts length to optimize energy use and movement. This design allows the drone to access branches from various angles, reach adjacent trees while tethered, and perform multitree sensing. Secondary perching via flexible arms enables repeated physical interactions across locations and over extended durations. Field tests show that tethered operation reduces energy consumption by up to 2.5 times compared to hovering. The system includes a leaf sampling tool and a reliable winding mechanism. Perching arm tests demonstrated increasing retention force with pulling angle, reaching up to 10 N, improving grip and fall resistance. This system offers an efficient, robust solution for robotic maneuvering and sensing in forest canopies, advancing in situ environmental monitoring capabilities.