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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#00274c">
<meta name="description" content="STEMbot is a compliant miniature climbing robot for autonomous under-canopy plant navigation, semantic mapping, and branch-aware motion planning.">
<meta name="keywords" content="STEMbot, climbing robot, agricultural robotics, plant navigation, semantic mapping, motion planning, IROS 2026">
<meta property="og:title" content="STEMbot: A Compliant Robot for Under-Canopy Plant Navigation">
<meta property="og:description" content="A miniature compliant robot for autonomous localization, semantic mapping, and branch-aware navigation under plant canopies.">
<meta property="og:image" content="./static/media/images/figures/hero.jpg">
<meta property="og:type" content="website">
<title>STEMbot | Under-Canopy Plant Navigation</title>
<link rel="icon" type="image/png" href="./static/media/images/favicon.png">
<link rel="stylesheet" href="./static/css/bulma.min.css">
<link rel="stylesheet" href="./static/css/index.css">
<script defer src="./static/js/index.js"></script>
</head>
<body>
<a class="skip-link" href="#main-content">Skip to main content</a>
<header class="site-header" id="top">
<nav class="navbar is-fixed-top" aria-label="Primary navigation">
<div class="container is-max-widescreen">
<div class="navbar-brand">
<a class="navbar-item brand-mark" href="#top" aria-label="STEMbot home">
<img src="./static/media/images/stembot-logo.png" alt="" width="36" height="36">
<span>STEMbot</span>
</a>
<button class="navbar-burger" type="button" aria-label="Open navigation menu" aria-expanded="false" data-menu-button>
<span aria-hidden="true"></span>
<span aria-hidden="true"></span>
<span aria-hidden="true"></span>
</button>
</div>
<div class="navbar-menu" data-menu>
<div class="navbar-end">
<a class="navbar-item" href="#video">Video</a>
<a class="navbar-item" href="#overview">Overview</a>
<a class="navbar-item" href="#system">System</a>
<a class="navbar-item" href="#hardware">Hardware</a>
<a class="navbar-item" href="#perception">Perception</a>
<a class="navbar-item" href="#planning">Planning</a>
<a class="navbar-item" href="#traversal">Traversal</a>
<a class="navbar-item" href="#experiments">Experiments</a>
<a class="navbar-item" href="#citation">Citation</a>
</div>
</div>
</div>
</nav>
<section class="hero publication-hero">
<div class="hero-body">
<div class="container is-max-widescreen">
<div class="hero-grid">
<div class="hero-copy">
<p class="eyebrow">Accepted to IROS 2026 · Pittsburgh, Pennsylvania</p>
<h1>STEMbot: A Compliant Robot for Under-Canopy Plant Navigation</h1>
<p class="authors">
<span>Zachary Charlick</span>,
<span>Nilay Roy Choudhury</span>,
<span>Haoyu Ma</span>,
<span>Xiaonan Huang</span>, and
<span>Dmitry Berenson</span>
</p>
<div class="affiliations" aria-label="Author affiliations">
<p>
<a href="https://robotics.umich.edu/">Department of Robotics, University of Michigan</a>
</p>
</div>
<p class="hero-summary">
A miniature climbing robot that combines compliant locomotion,
geometric SLAM, semantic mapping, and manifold-constrained
planning to autonomously navigate plant stems and branches.
</p>
<div class="resource-links" aria-label="Publication resources">
<a class="button resource-button is-primary" href="./static/media/STEMbot_paper.pdf">
<span>Paper</span>
<span aria-hidden="true">↗</span>
</a>
<a class="button resource-button" href="#video">
<span>Video</span>
<span aria-hidden="true">↓</span>
</a>
<a class="button resource-button" href="https://github.com/UM-ARM-Lab/stembot">
<span>Code</span>
<span aria-hidden="true">↗</span>
</a>
<a class="button resource-button" href="https://arxiv.org/abs/2607.07873">
<span>arXiv</span>
<span aria-hidden="true">↗</span>
</a>
</div>
</div>
<figure class="hero-figure">
<img src="./static/media/images/figures/hero.jpg"
alt="STEMbot attached to a green plant stem beneath broad leaves."
width="1750" height="1050">
<figcaption>STEMbot navigating beneath a plant canopy.</figcaption>
</figure>
</div>
</div>
</div>
</section>
</header>
<main id="main-content">
<section class="section" id="video">
<div class="container is-max-desktop">
<div class="section-heading">
<p class="section-kicker">Presentation video</p>
<h2>STEMbot in five minutes</h2>
<p>The complete project video covers the motivation, system design, methods, and experimental evaluation.</p>
</div>
<video class="presentation-video" controls playsinline preload="metadata"
poster="./static/media/posters/stembot-presentation.jpg"
aria-label="Five-minute STEMbot project presentation">
<source src="./static/media/videos/stembot-presentation.mp4" type="video/mp4">
</video>
</div>
</section>
<section class="section section-light" id="overview">
<div class="container is-max-desktop">
<div class="section-heading">
<p class="section-kicker">Overview</p>
<h2>Reaching the places conventional crop robots cannot see</h2>
</div>
<div class="abstract-copy">
<p>
The scalability of organic agriculture is partially limited by the
labor costs associated with monitoring for pests. While drones and
rovers are well-suited for agricultural monitoring from above or
next to plants, many pests live on the underside of leaves or on
plant stems, making them detectable only after they have caused
significant damage.
</p>
<p>
STEMbot is a miniature climbing robot system designed for autonomous
navigation under plant canopies. It integrates a fully geometric
PIN-SLAM pipeline with a semantic OcTree, a manifold-constrained A*
planner, and ray-tracing goal specification for branch-aware
traversal and plant inspection.
</p>
</div>
<div class="metric-grid" aria-label="Key results">
<article class="metric-card">
<strong>7–33 mm</strong>
<span>demonstrated stem-diameter range</span>
</article>
<article class="metric-card">
<strong>90°</strong>
<span>demonstrated branch traversal</span>
</article>
<article class="metric-card">
<strong>50 mm</strong>
<span>tightest demonstrated curvature radius</span>
</article>
<article class="metric-card">
<strong>4 plants</strong>
<span>autonomous navigation trials</span>
</article>
</div>
<div class="contribution-panel">
<h3>Contributions</h3>
<ol class="contribution-list">
<li>A miniature compliant robot that traverses stems, transitions onto branches, and maintains contact while fully inverted.</li>
<li>A semantic OcTree pipeline combining PIN-SLAM, SAM, and CLIP for geometric reconstruction and semantic odometry.</li>
<li>A manifold-constrained A* planner for branch-aware navigation along plant structures.</li>
<li>Hardware experiments on artificial and live plants evaluating traversal, mapping, and autonomous navigation.</li>
</ol>
</div>
</div>
</section>
<section class="section" id="system">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Integrated system</p>
<h2>Perception, planning, and control in one climbing platform</h2>
<p>
RGB-D vision builds a geometric and
semantic representation of the plant. A receding-horizon planner
searches that representation and dispatches discrete locomotion
primitives to the robot.
</p>
</div>
<figure class="paper-figure paper-figure-wide">
<img src="./static/media/images/figures/system.png"
alt="STEMbot system diagram showing sensing and perception, motion planning, and control subsystems."
loading="lazy" width="2000" height="700">
<figcaption>
System architecture: PIN-SLAM and semantic mapping estimate the
traversable manifold, A* computes a path, and closed-loop control
executes the selected action primitive.
</figcaption>
</figure>
</div>
</section>
<section class="section section-tinted" id="hardware">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Hardware</p>
<h2>Compliant grip without fully enclosing the stem</h2>
</div>
<div class="feature-grid">
<div class="feature-copy">
<p>
Two motor pairs drive concave, high-friction EcoFlex wheels. A
spring-loaded four-bar linkage maintains contact across varying
stem diameters while allowing branches and protrusions to pass
through the robot’s open geometry.
</p>
<p>
Coordinated wheel motion provides three primitives: longitudinal
traversal, circumferential yaw, and pitch adjustment. An Intel
RealSense D405 camera—incorporating the D401 depth module—supports
stereo depth sensing, while a VL6180X time-of-flight sensor feeds
a closed-loop pitch controller.
</p>
<ul class="fact-list">
<li>Four 700:1 sub-micro planetary gearmotors</li>
<li>Compliant EcoFlex 00-45 wheel surfaces</li>
<li>Vertical, yaw, and pitch motion primitives</li>
<li>90 Hz time-of-flight feedback control</li>
</ul>
</div>
<figure class="paper-figure">
<img src="./static/media/images/figures/hardware.jpg"
alt="Exploded STEMbot hardware diagram and illustrations of vertical, yaw, and pitch motion."
loading="lazy" width="2000" height="1700">
<figcaption>Exploded hardware design and coordinated locomotion modes.</figcaption>
</figure>
</div>
<div class="media-pair">
<figure class="paper-figure">
<img src="./static/media/images/hardware-detail.jpg"
alt="Labeled exploded view of STEMbot components including motors, compliant wheels, camera, and time-of-flight sensor."
loading="lazy" width="1400" height="788">
<figcaption>Exploded view, hardware component breakdown.</figcaption>
</figure>
<article class="video-card video-card-large">
<video controls muted playsinline preload="none"
poster="./static/media/posters/assembly-overview.jpg"
data-observe-video aria-label="Condensed STEMbot assembly process">
<source src="./static/media/videos/assembly-overview.mp4" type="video/mp4">
</video>
<div class="video-card-copy">
<p>Assembly timelapse condensed to one minute.</p>
</div>
</article>
</div>
</div>
</section>
<section class="section" id="perception">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Perception</p>
<h2>Geometry-first localization with semantic structure</h2>
<p>
PIN-SLAM registers depth observations without relying on repetitive
plant appearance. SAM proposes image masks, CLIP classifies them,
and high-confidence depth observations are fused into a
probabilistic semantic OcTree.
</p>
</div>
<div class="feature-grid feature-grid-reverse">
<figure class="paper-figure">
<img src="./static/media/images/figures/perception.jpg"
alt="Perception pipeline with RGB and depth input, SAM masks, CLIP-refined semantic classes, and a registered semantic point cloud."
loading="lazy" width="2000" height="1100">
<figcaption>
RGB-D observations become semantic point clouds registered in a
globally consistent frame.
</figcaption>
</figure>
<div class="feature-copy">
<h3>Semantic manifold estimation</h3>
<p>
Traversable stem voxels are indexed for efficient spatial
queries. Principal component analysis estimates the local surface
normal and longitudinal branch heading used by the planner.
</p>
<article class="video-card">
<video controls muted loop playsinline preload="none"
poster="./static/media/posters/perception-demo.jpg"
data-observe-video aria-label="Semantic perception demonstration">
<source src="./static/media/videos/perception-demo.mp4" type="video/mp4">
</video>
<div class="video-card-copy">
<h4>Perception demonstration</h4>
<p>Traversable plant structure is separated from surrounding geometry. Our bayesian mapping is robust to false negatives and occasional semantic misclassifications.</p>
</div>
</article>
</div>
</div>
</div>
</section>
<section class="section section-dark" id="planning">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Motion planning</p>
<h2>A* search constrained to the plant manifold</h2>
<p>
Each state stores a position, surface normal, and proximal or distal
branch heading. Candidate actions are projected back to nearby
traversable voxels, checked for collision and orientation
consistency, and pruned when a branch transition violates docking
geometry.
</p>
</div>
<div class="figure-grid figure-grid-three">
<figure class="paper-figure">
<img src="./static/media/images/figures/heading-constraints.png"
alt="Diagram defining proximal and distal branch heading vectors for STEMbot."
loading="lazy" width="2000" height="600">
<figcaption>Branch heading is constrained to proximal or distal directions.</figcaption>
</figure>
<figure class="paper-figure">
<img src="./static/media/images/figures/state-projection.png"
alt="Diagram showing a robot state, naive action, and correction back to the nearest traversable voxel."
loading="lazy" width="2000" height="950">
<figcaption>Action successors are projected back onto the semantic manifold.</figcaption>
</figure>
<figure class="paper-figure">
<img src="./static/media/images/figures/branch-transition.jpg"
alt="Comparison of invalid and valid branch transitions based on heading geometry."
loading="lazy" width="2000" height="1150">
<figcaption>Branch-switch constraints remove physically infeasible successors.</figcaption>
</figure>
</div>
<div class="planning-goal">
<figure class="paper-figure">
<img src="./static/media/images/figures/goal-generation.jpg"
alt="Visibility-goal diagram with Fibonacci-sphere rays cast from an inspection target toward traversable plant surfaces."
loading="lazy" width="2000" height="1300">
<figcaption>Visibility-constrained goal generation by radial ray casting.</figcaption>
</figure>
<div>
<h3>Two goal modalities</h3>
<p>
State goals move the robot to a specified manifold coordinate.
Visibility goals instead identify robot states from which a
target point lies inside the camera frustum without stem or leaf
occlusion.
</p>
<p>
Only the first action of each planned path is executed. The
system then replans from updated odometry, allowing it to account
for wheel slip, stem irregularities, and contact not represented
by the model.
</p>
</div>
</div>
</div>
</section>
<section class="section" id="traversal">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Traversal capability</p>
<h2>Mechanical limits across diameter, curvature, and junction angle</h2>
<p>
Bench tests isolate individual geometric variables using common
cylindrical objects and 3D-printed PLA fixtures.
</p>
</div>
<figure class="paper-figure paper-figure-wide">
<img src="./static/media/images/figures/traversal-extremes.png"
alt="STEMbot traversing a 33 millimeter frame, a 7 millimeter pen, a 50 millimeter radius curve, and a 90 degree branch."
loading="lazy" width="2000" height="600">
<figcaption>Reported traversal extremes from the hardware evaluation.</figcaption>
</figure>
<div class="traversal-group">
<div class="subsection-heading">
<h3>Stem diameter</h3>
<p>Nine supplied trials spanning 8–25 mm.</p>
</div>
<div class="clip-grid">
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-8mm.jpg" data-observe-video aria-label="STEMbot traversing an 8 millimeter stem"><source src="./static/media/videos/diameter-8mm.mp4" type="video/mp4"></video>
<span>8 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-9mm.jpg" data-observe-video aria-label="STEMbot traversing a 9 millimeter stem"><source src="./static/media/videos/diameter-9mm.mp4" type="video/mp4"></video>
<span>9 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-10mm.jpg" data-observe-video aria-label="STEMbot traversing a 10 millimeter stem"><source src="./static/media/videos/diameter-10mm.mp4" type="video/mp4"></video>
<span>10 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-12mm.jpg" data-observe-video aria-label="STEMbot traversing a 12 millimeter stem"><source src="./static/media/videos/diameter-12mm.mp4" type="video/mp4"></video>
<span>12 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-14mm.jpg" data-observe-video aria-label="STEMbot traversing a 14 millimeter stem"><source src="./static/media/videos/diameter-14mm.mp4" type="video/mp4"></video>
<span>14 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-16mm.jpg" data-observe-video aria-label="STEMbot traversing a 16 millimeter stem"><source src="./static/media/videos/diameter-16mm.mp4" type="video/mp4"></video>
<span>16 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-18mm.jpg" data-observe-video aria-label="STEMbot traversing an 18 millimeter stem"><source src="./static/media/videos/diameter-18mm.mp4" type="video/mp4"></video>
<span>18 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-20mm.jpg" data-observe-video aria-label="STEMbot traversing a 20 millimeter stem"><source src="./static/media/videos/diameter-20mm.mp4" type="video/mp4"></video>
<span>20 mm</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/diameter-25mm.jpg" data-observe-video aria-label="STEMbot traversing a 25 millimeter stem"><source src="./static/media/videos/diameter-25mm.mp4" type="video/mp4"></video>
<span>25 mm</span>
</article>
</div>
</div>
<div class="traversal-group">
<div class="subsection-heading">
<h3>Branch transitions and curvature</h3>
<p>The 120° clip documents a failed transition outside the demonstrated 90° capability.</p>
</div>
<div class="clip-grid clip-grid-seven">
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-angle-30.jpg" data-observe-video aria-label="STEMbot traversing a 30 degree branch junction"><source src="./static/media/videos/branch-angle-30.mp4" type="video/mp4"></video>
<span>30° junction</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-angle-60.jpg" data-observe-video aria-label="STEMbot traversing a 60 degree branch junction"><source src="./static/media/videos/branch-angle-60.mp4" type="video/mp4"></video>
<span>60° junction</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-angle-90.jpg" data-observe-video aria-label="STEMbot traversing a 90 degree branch junction"><source src="./static/media/videos/branch-angle-90.mp4" type="video/mp4"></video>
<span>90° junction</span>
</article>
<article class="mini-video-card is-failure">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-angle-120-failure.jpg" data-observe-video aria-label="Failed STEMbot transition at a 120 degree branch junction"><source src="./static/media/videos/branch-angle-120-failure.mp4" type="video/mp4"></video>
<span>120° · failed</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-curve-r50.jpg" data-observe-video aria-label="STEMbot traversing a curve with 50 millimeter radius"><source src="./static/media/videos/branch-curve-r50.mp4" type="video/mp4"></video>
<span>50 mm radius</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-curve-r75.jpg" data-observe-video aria-label="STEMbot traversing a curve with 75 millimeter radius"><source src="./static/media/videos/branch-curve-r75.mp4" type="video/mp4"></video>
<span>75 mm radius</span>
</article>
<article class="mini-video-card">
<video controls muted loop playsinline preload="none" data-autoplay poster="./static/media/posters/branch-curve-r100.jpg" data-observe-video aria-label="STEMbot traversing a curve with 100 millimeter radius"><source src="./static/media/videos/branch-curve-r100.mp4" type="video/mp4"></video>
<span>100 mm radius</span>
</article>
</div>
</div>
</div>
</section>
<section class="section section-tinted" id="experiments">
<div class="container is-max-widescreen">
<div class="section-heading">
<p class="section-kicker">Autonomous experiments</p>
<h2>Mapping and navigation across artificial and live plants</h2>
<p>
The evaluation uses state goals for Dracaena and Ficus and
visibility-constrained goals for Monstera and Olea. Robot and map
videos below are complete-run timelapses.
</p>
</div>
<figure class="paper-figure paper-figure-wide results-overview">
<img src="./static/media/images/figures/mapping-experiments.jpg"
alt="Four experimental plant trials showing specimens, initial and final robot poses, plans, semantic maps, and Chamfer error maps."
loading="lazy" width="4200" height="3000">
<figcaption>
Experimental overview from the paper: physical specimens, robot
poses, representative plans, semantic overlays, and one-way Chamfer
error heatmaps.
</figcaption>
</figure>
<div class="experiment-stack">
<article class="experiment-card">
<header class="experiment-header">
<div class="experiment-number">01</div>
<img src="./static/media/images/plant-5.webp" alt="Artificial Dracaena specimen." loading="lazy" width="433" height="577">
<div>
<p class="experiment-type">Artificial specimen · State goal</p>
<h3>Dracaena</h3>
<p>A static artificial plant used to evaluate autonomous navigation and globally consistent semantic reconstruction.</p>
</div>
</header>
<div class="experiment-media">
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-1-robot.jpg" data-observe-video aria-label="Dracaena robot trial timelapse"><source src="./static/media/videos/experiment-1-robot.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Robot trial</h4></div></article>
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-1-map.jpg" data-observe-video aria-label="Dracaena map and planner timelapse"><source src="./static/media/videos/experiment-1-map.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Map and plan</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-1-semantic-overlay.jpg" data-observe-video aria-label="Dracaena semantic reconstruction rotation"><source src="./static/media/videos/experiment-1-semantic-overlay.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Semantic reconstruction</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-1-chamfer-heatmap.jpg" data-observe-video aria-label="Dracaena Chamfer error heatmap rotation"><source src="./static/media/videos/experiment-1-chamfer-heatmap.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Chamfer error</h4></div></article>
</div>
</article>
<article class="experiment-card">
<header class="experiment-header">
<div class="experiment-number">02</div>
<img src="./static/media/images/plant-6.webp" alt="Live Monstera deliciosa specimen." loading="lazy" width="433" height="577">
<div>
<p class="experiment-type">Live specimen · Visibility goal</p>
<h3>Monstera deliciosa</h3>
<p>A visibility-constrained trial on a live plant with low color contrast and complex leaf geometry.</p>
</div>
</header>
<div class="experiment-media">
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-2-robot.jpg" data-observe-video aria-label="Monstera robot trial timelapse"><source src="./static/media/videos/experiment-2-robot.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Robot trial</h4></div></article>
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-2-map.jpg" data-observe-video aria-label="Monstera map and planner timelapse"><source src="./static/media/videos/experiment-2-map.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Map and plan</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-2-semantic-overlay.jpg" data-observe-video aria-label="Monstera semantic reconstruction rotation"><source src="./static/media/videos/experiment-2-semantic-overlay.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Semantic reconstruction</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-2-chamfer-heatmap.jpg" data-observe-video aria-label="Monstera Chamfer error heatmap rotation"><source src="./static/media/videos/experiment-2-chamfer-heatmap.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Chamfer error</h4></div></article>
</div>
</article>
<article class="experiment-card">
<header class="experiment-header">
<div class="experiment-number">03</div>
<img src="./static/media/images/plant-2.webp" alt="Live Ficus lyrata specimen." loading="lazy" width="383" height="652">
<div>
<p class="experiment-type">Live specimen · State goal</p>
<h3>Ficus lyrata</h3>
<p>A state-goal navigation trial on a tall live specimen used to evaluate mapping consistency over an extended trajectory.</p>
</div>
</header>
<div class="experiment-media">
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-3-robot.jpg" data-observe-video aria-label="Ficus robot trial timelapse"><source src="./static/media/videos/experiment-3-robot.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Robot trial</h4></div></article>
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-3-map.jpg" data-observe-video aria-label="Ficus map and planner timelapse"><source src="./static/media/videos/experiment-3-map.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Map and plan</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-3-semantic-overlay.jpg" data-observe-video aria-label="Ficus semantic reconstruction rotation"><source src="./static/media/videos/experiment-3-semantic-overlay.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Semantic reconstruction</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-3-chamfer-heatmap.jpg" data-observe-video aria-label="Ficus Chamfer error heatmap rotation"><source src="./static/media/videos/experiment-3-chamfer-heatmap.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Chamfer error</h4></div></article>
</div>
</article>
<article class="experiment-card">
<header class="experiment-header">
<div class="experiment-number">04</div>
<img src="./static/media/images/plant-3.webp" alt="Artificial Olea europaea specimen." loading="lazy" width="364" height="686">
<div>
<p class="experiment-type">Artificial specimen · Visibility goal</p>
<h3>Olea europaea</h3>
<p>A visibility-goal trial requiring the robot to reorient before transitioning between artificial branches.</p>
</div>
</header>
<div class="experiment-media">
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-4-robot.jpg" data-observe-video aria-label="Olea robot trial timelapse"><source src="./static/media/videos/experiment-4-robot.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Robot trial</h4></div></article>
<article class="video-card"><video controls muted playsinline preload="none" poster="./static/media/posters/experiment-4-map.jpg" data-observe-video aria-label="Olea map and planner timelapse"><source src="./static/media/videos/experiment-4-map.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Map and plan</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-4-semantic-overlay.jpg" data-observe-video aria-label="Olea semantic reconstruction rotation"><source src="./static/media/videos/experiment-4-semantic-overlay.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Semantic reconstruction</h4></div></article>
<article class="video-card"><video controls muted loop playsinline preload="none" poster="./static/media/posters/experiment-4-chamfer-heatmap.jpg" data-observe-video aria-label="Olea Chamfer error heatmap rotation"><source src="./static/media/videos/experiment-4-chamfer-heatmap.mp4" type="video/mp4"></video><div class="video-card-copy"><h4>Chamfer error</h4></div></article>
</div>
</article>
</div>
<div class="results-grid">
<figure class="paper-figure">
<img src="./static/media/images/figures/chamfer-metrics.png"
alt="Bar chart comparing one-way Chamfer distance for Dracaena, Monstera, Ficus, and Olea."
loading="lazy" width="2000" height="1750">
<figcaption>One-way Chamfer distance by plant and semantic class.</figcaption>
</figure>
<div class="results-copy">
<p class="section-kicker">Mapping accuracy</p>
<h3>Globally consistent geometry for closed-loop navigation</h3>
<div class="result-stat">
<strong>3.85 mm</strong>
<span>mean one-way Chamfer distance across artificial specimens</span>
</div>
<div class="result-stat">
<strong>13.36 mm</strong>
<span>mean one-way Chamfer distance across live specimens</span>
</div>
<p>
Higher live-plant error is attributed to organic
non-rigidity, biological growth between baseline and trial scans,
and a semantic misclassification on the Monstera.
</p>
</div>
</div>
<aside class="limitations">
<h3>Current limitations</h3>
<p>
The planner assumes static plant geometry and does not yet choose
inspection targets based on information gain. Accounting for
bending or swaying plants and validating the system in in-situ
agricultural environments remain future work. Further experimentation is needed
to prove and improve reliability, and hardware iteration is required to untether
the robot.
</p>
</aside>
</div>
</section>
<section class="section section-dark" id="citation">
<div class="container is-max-desktop">
<div class="section-heading">
<p class="section-kicker">Citation</p>
<h2>BibTeX</h2>
<p>
Please cite the arXiv preprint for now. This entry will be updated
when the final IROS proceedings metadata becomes available.
</p>
</div>
<div class="citation-block">
<button class="copy-button" type="button" data-copy-citation>Copy BibTeX</button>
<pre><code id="bibtex">@misc{charlick2026stembotcompliantrobotundercanopy,
title={STEMbot: A Compliant Robot for Under-Canopy Plant Navigation},
author={Zachary Charlick and Nilay Roy Choudhury and Haoyu Ma and Xiaonan Huang and Dmitry Berenson},
year={2026},
eprint={2607.07873},
archivePrefix={arXiv},
primaryClass={cs.RO},
url={https://arxiv.org/abs/2607.07873},
}</code></pre>
</div>
<div class="acknowledgment-note">
<strong>Acknowledgments and funding:</strong>
This work was supported in part by the Office of Naval Research Grant
N00014-24-1-2036, NSF grants IIS-2113401 and IIS-2220876, and the
National Robotics Initiative, project award no. 2026-67021-46039,
from the U.S. Department of Agriculture’s National Institute of Food
and Agriculture.
</div>
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<p>A compliant robot for under-canopy plant navigation.</p>
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