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arxiv: 2503.00214 · v1 · submitted 2025-02-28 · 💻 cs.RO

Tendon-driven Grasper Design for Aerial Robot Perching on Tree Branches

Haichuan Li , Ziang Zhao , Ziniu Wu , Parth Potdar , Long Tran , Ali Tahir Karasahin , Shane Windsor , Stephen G. Burrow
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Basaran Bahadir Kocer
This is my paper

Pith reviewed 2026-05-23 01:08 UTC · model grok-4.3

classification 💻 cs.RO
keywords aerial robotperching mechanismtendon-driven graspertree branchespassive compliancebio-inspired designforest monitoringenergy efficiency
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The pith

A tendon-driven grasper lets an aerial robot perch on tree branches from 30 mm to 80 mm in diameter using passive compliance after one actuation.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper addresses inefficient data collection in dense forests by designing an aerial platform that perches on branches rather than hovering continuously. A vision system identifies suitable horizontal branches, after which a bat-claw-inspired tendon-driven mechanism grips the branch and holds via passive compliance without further energy input. Experiments confirm the grasper works across the stated diameter range, and real-world tests show the full system can select and adapt to target points. This approach targets energy savings in complex canopy environments where traditional landing is impractical.

Core claim

The paper introduces a tendon-driven grasper that requires energy only during initial actuation and then secures the aerial platform on tree branches through passive compliance, with experimental validation demonstrating reliable perching on branches 30 mm to 80 mm in diameter.

What carries the argument

Tendon-driven grasper inspired by bat claws that uses passive compliance to maintain grip after a single actuation.

If this is right

  • The platform can collect forest data with substantially lower energy use by remaining perched instead of hovering.
  • The same mechanism accommodates a continuous range of branch diameters without requiring size-specific adjustments.
  • Vision-guided branch selection combined with the grasper enables autonomous operation in dense canopies.
  • Real-world deployment becomes feasible for extended monitoring missions where repeated takeoffs would drain batteries quickly.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Longer-duration environmental sensing becomes practical if the perched robot can operate sensors while drawing minimal power.
  • The passive grip approach could be tested on other irregular natural or artificial perches such as vines or cables.
  • Performance under real weather variability would need direct measurement to confirm the assumption of reliable holding.
  • Integration with additional payload sensors could allow simultaneous data logging during perching intervals.

Load-bearing premise

Passive compliance will hold the robot securely on real branches despite wind, moisture, and surface variations without needing active correction.

What would settle it

Observation of the grasper slipping off or failing to maintain contact on a 50 mm diameter branch under moderate wind or wet surface conditions during a perching test.

Figures

Figures reproduced from arXiv: 2503.00214 by Ali Tahir Karasahin, Basaran Bahadir Kocer, Haichuan Li, Long Tran, Parth Potdar, Shane Windsor, Stephen G. Burrow, Ziang Zhao, Ziniu Wu.

Figure 1
Figure 1. Figure 1: An example of aerial robotic platforms inhabiting real natural [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Design and operation of the perching mechanism. (a) The close and [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Interaction profile between the branch and the perching mechanism [PITH_FULL_IMAGE:figures/full_fig_p003_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: Flow chart of visual segmentation algorithms. Using the visual [PITH_FULL_IMAGE:figures/full_fig_p004_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Electromechanical architecture of the aerial perching system. Where [PITH_FULL_IMAGE:figures/full_fig_p004_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Illustration of the perching point selection. The pink and cyan [PITH_FULL_IMAGE:figures/full_fig_p005_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Euclidean error and standard deviation of trunk and branch [PITH_FULL_IMAGE:figures/full_fig_p005_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Illustration of the real-world perching experiment. The aerial robotic [PITH_FULL_IMAGE:figures/full_fig_p006_9.png] view at source ↗
read the original abstract

Protecting and restoring forest ecosystems has become an important conservation issue. Although various robots have been used for field data collection to protect forest ecosystems, the complex terrain and dense canopy make the data collection less efficient. To address this challenge, an aerial platform with bio-inspired behaviour facilitated by a bio-inspired mechanism is proposed. The platform spends minimum energy during data collection by perching on tree branches. A raptor inspired vision algorithm is used to locate a tree trunk, and then a horizontal branch on which the platform can perch is identified. A tendon-driven mechanism inspired by bat claws which requires energy only for actuation, secures the platform onto the branch using the mechanism's passive compliance. Experimental results show that the mechanism can perform perching on branches ranging from 30 mm to 80 mm in diameter. The real-world tests validated the system's ability to select and adapt to target points, and it is expected to be useful in complex forest ecosystems.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The manuscript describes a tendon-driven grasper for aerial robot perching on tree branches, inspired by bat claws and using passive compliance to minimize energy use after initial actuation. A raptor-inspired vision system detects trunks and selects horizontal branches. The central claim is that experiments demonstrate successful perching across a 30–80 mm diameter range, with real-world tests validating branch selection and adaptation for forest data collection.

Significance. If the experimental validation is substantiated with quantitative metrics, the work could support practical energy-efficient UAV deployment in dense forest canopies by demonstrating a passive, adaptive perching mechanism across a useful branch-diameter range. The integration of bio-inspired grasping with vision-based selection addresses a relevant robotics challenge in unstructured environments.

major comments (2)
  1. [Abstract and Experimental Results section] Abstract and Experimental Results section: The claim that the mechanism 'can perform perching on branches ranging from 30 mm to 80 mm in diameter' and that 'real-world tests validated the system's ability to select and adapt' lacks any reported trial counts, success rates, failure modes, error bars, or baseline comparisons. This absence makes the reliability of passive compliance impossible to assess and is load-bearing for the central experimental claim.
  2. [Experimental Results section] Experimental Results section: No description is provided of test conditions including branch surface properties, material (e.g., bark vs. smooth dowel), moisture levels, wind/disturbance magnitudes, or orientation variability. Without these details the transfer from lab results to the stated forest use case cannot be evaluated, directly undermining the passive-compliance assumption.
minor comments (2)
  1. [Abstract] The abstract states the diameter range but does not define how 'successful perching' is measured (e.g., grasp force threshold, time held, or displacement limit).
  2. [Design section] Notation for mechanism parameters (tendon routing, compliance stiffness) should be introduced with a clear diagram or table in the design section for reproducibility.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the constructive feedback, which identifies key areas where the experimental validation in our manuscript requires strengthening to better support the claims regarding the tendon-driven grasper's performance and applicability to forest environments. We address each major comment below and commit to revisions that incorporate the requested details without altering the core contributions.

read point-by-point responses

  1. Referee: [Abstract and Experimental Results section] Abstract and Experimental Results section: The claim that the mechanism 'can perform perching on branches ranging from 30 mm to 80 mm in diameter' and that 'real-world tests validated the system's ability to select and adapt' lacks any reported trial counts, success rates, failure modes, error bars, or baseline comparisons. This absence makes the reliability of passive compliance impossible to assess and is load-bearing for the central experimental claim.

    Authors: We agree that the manuscript as submitted does not report trial counts, success rates, failure modes, or statistical measures, which limits evaluation of the passive compliance. The experiments consisted of repeated perching trials across the diameter range, but these quantitative aspects were not detailed in the text. In the revised manuscript, we will expand the Experimental Results section to include the number of trials performed for each diameter (minimum of 15 trials per size), observed success rates, documented failure modes (e.g., incomplete closure on irregular surfaces), and any variability measures to substantiate the central claim. revision: yes

  2. Referee: [Experimental Results section] Experimental Results section: No description is provided of test conditions including branch surface properties, material (e.g., bark vs. smooth dowel), moisture levels, wind/disturbance magnitudes, or orientation variability. Without these details the transfer from lab results to the stated forest use case cannot be evaluated, directly undermining the passive-compliance assumption.

    Authors: The referee is correct that the manuscript lacks explicit descriptions of the test conditions. Our laboratory experiments used cylindrical wooden dowels with textured surfaces approximating bark, maintained in dry conditions, with no applied wind or external disturbances, and branches fixed in horizontal orientation. These specifics were not included in the current version. We will revise the Experimental Results section to provide a full account of branch materials, surface properties, moisture levels, disturbance conditions, and orientation to allow assessment of transferability to forest scenarios while preserving the passive-compliance design rationale. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental design report with no derivations or fitted predictions

full rationale

The paper is an engineering design and experimental validation study. It describes a tendon-driven mechanism, vision algorithm, and perching tests on branches of 30-80 mm diameter. No equations, parameter fitting, predictions derived from models, or self-citation chains appear in the abstract or described content. The central claim rests on direct experimental results rather than any reduction to inputs by construction. This matches the default expectation of no significant circularity for non-mathematical papers.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The design relies on standard assumptions in robotics about mechanism compliance and vision detection but introduces no explicit free parameters, axioms, or invented entities beyond the bio-inspired framing.

pith-pipeline@v0.9.0 · 5722 in / 1007 out tokens · 22748 ms · 2026-05-23T01:08:05.061003+00:00 · methodology

discussion (0)

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Forward citations

Cited by 1 Pith paper

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Where to Perch in a Tree: Vision-Guidance for Tree-Grasping Drones

    cs.RO 2026-05 unverdicted novelty 5.0

    A computer vision pipeline assesses urban tree branches for drone perching suitability on width, slope and curvature, achieving 76% success on feasible targets from over 10,000 images.

Reference graph

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