AMBER: Aerial deployable gripping crawler with compliant microspine for canopy manipulation

TL;DR

This work addresses the challenge of accessing forest canopies by introducing AMBER, an aerially deployable, tethered crawler that combines a dual-track rotary grasper with compliant microspines and an elastic tail for robust branch gripping and traversal. The design emphasizes a compact, modular, and energy-efficient platform, validated through gripping and crawling experiments that reveal strong performance on varied branch geometries and inclinations. Key contributions include the DTRG mechanism with single-motor actuation and gear reductions, a lightweight track and body design, tail-assisted stability, and a drone-tether deployment workflow enabling in-canopy sampling with low power consumption. The system demonstrates promising applicability for environmental sensing and sampling with substantial energy advantages over hovering drones, paving the way for field deployments in forest canopies.

Abstract

This paper presents an aerially deployable crawler designed for adaptive locomotion and manipulation within tree canopies. The system combines compliant microspine-based tracks, a dual-track rotary gripper, and an elastic tail, enabling secure attachment and stable traversal across branches of varying curvature and inclination. Experiments demonstrate reliable gripping up to 90 degrees of body roll and inclination, while effective climbing on branches inclined up to 67.5 degrees, achieving a maximum speed of 0.55 body lengths per second on horizontal branches. The compliant tracks allow yaw steering of up to 10 degrees, enhancing maneuverability on irregular surfaces. Power measurements show efficient operation with a dimensionless cost of transport over an order of magnitude lower than typical hovering power consumption in aerial robots. Integrated within a drone-tether deployment system, the crawler provides a robust, low-power platform for environmental sampling and in-canopy sensing, bridging the gap between aerial and surface-based ecological robotics.

Figures (6)

• Figure 1: Mission concept of the AMBER framework: the drone deploys the crawler onto a branch, perches, and the crawler traverses the branch to perform sampling before being retrieved by the drone.
• Figure 2: Crawler design with a focus on the gripping mechanism, the track system, the microspine element and the tail.
• Figure 3: Track body (in grey) illustrating the actuation of the spine carriers. (a) Intermediate chain link, (b) Retainer. (c) Compliant microspine design consisting of a frame, spring, and spine carrier, allowing lateral movement that facilitates crawler maneuverability.
• Figure 4: Normal pull-off force at different gripping angles.
• Figure 5: (a) Normal pull forces measured at various pitch angles for both the tail and no-tail configurations on a branch with a 95 mm diameter. (b) Pull off normal and tangential forces at different angles around the branch (Roll). (c) Pull off normal and tangential forces at Yaw angles up to 20°. (d) Power consumption while crawling at different inclinations.