https://mulhamfetna.com/tags/engineering/ Recent content in Engineering on Mulham Fetna Hugo -- gohugo.io en contact@mulhamfetna.com (Mulham Fetna) contact@mulhamfetna.com (Mulham Fetna) © 2026 Mulham Fetna Wed, 16 Sep 2026 00:00:00 +0000 https://mulhamfetna.com/projects/ros2-tendon-driven-hand-mujoco-digital-twin-vision-teleoperation/roadmap-to-production/ Wed, 16 Sep 2026 00:00:00 +0000 contact@mulhamfetna.com (Mulham Fetna) https://mulhamfetna.com/projects/ros2-tendon-driven-hand-mujoco-digital-twin-vision-teleoperation/roadmap-to-production/ <div class="lead text-neutral-500 dark:text-neutral-400 !mb-9 text-xl"> The system works, and it teaches well. Getting it to drive real servos safely is a sequence of well-scoped upgrades — each one grounded in a limitation measured earlier in this series. </div> <h2 class="relative group">Where it stands <div id="where-it-stands" class="anchor"></div> <span class="absolute top-0 w-6 transition-opacity opacity-0 -start-6 not-prose group-hover:opacity-100 select-none"> <a class="text-primary-300 dark:text-neutral-700 !no-underline" href="#where-it-stands" aria-label="Anchor">#</a> </span> </h2> <table> <thead> <tr> <th>Area</th> <th>Today</th> <th>Production target</th> </tr> </thead> <tbody> <tr> <td>Hand tracking</td> <td>image-normalized landmarks, one global calibration</td> <td>metric world landmarks, per-finger calibration, a temporal filter</td> </tr> <tr> <td>Command mapping</td> <td>flexion → ±50 N; the twin is a switch</td> <td>flexion → tendon length; proportional curl</td> </tr> <tr> <td>Physics model</td> <td>force motors, decorative horns, no self-contact</td> <td>position servos on horns, tuned stiffness, contacts for grasping</td> </tr> <tr> <td>Middleware</td> <td>one topic, default QoS, open on the LAN</td> <td>parameters, explicit QoS, a watchdog, SROS 2</td> </tr> <tr> <td>Containers</td> <td>privileged, host namespaces, root, <code>xhost</code></td> <td>least privilege, non-root, optional headless</td> </tr> <tr> <td>Code</td> <td>classes copied into three files, no tests</td> <td>one shared package, tests, CI</td> </tr> <tr> <td>Hardware</td> <td>simulation only</td> <td>a servo driver on the same topic</td> </tr> </tbody> </table> <ol class="border-s-2 border-primary-500 dark:border-primary-300 list-none"> <li> <div class="flex"> <div class="bg-primary-500 dark:bg-primary-300 text-neutral-50 dark:text-neutral-700 min-w-[30px] h-8 text-2xl flex items-center justify-center rounded-full ltr:-ml-12 rtl:-mr-[79px] mt-5"> <span class="relative block icon"><svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><path fill="currentColor" d="M438.6 105.4C451.1 117.9 451.1 138.1 438.6 150.6L182.6 406.6C170.1 419.1 149.9 419.1 137.4 406.6L9.372 278.6C-3.124 266.1-3.124 245.9 9.372 233.4C21.87 220.9 42.13 220.9 54.63 233.4L159.1 338.7L393.4 105.4C405.9 92.88 426.1 92.88 438.6 105.4H438.6z"/></svg> </span> </div> <div class="block p-6 rounded-lg shadow-2xl flex-1 ms-6 mb-10 break-words"> <div class="flex justify-between"> <h2 class="mt-0">Stage 1 · Correctness</h2> </div> <h4 class="mt-0"> Measure the right thing, command the right quantity </h4> <div class="mb-6"> <p><strong>World landmarks.</strong> Image-normalized coordinates bend angles by up to 16° with hand orientation (<a href="https://mulhamfetna.com/projects/ros2-tendon-driven-hand-mujoco-digital-twin-vision-teleoperation/mediapipe-hands/" >Part 4</a>). Read <code>multi_hand_world_landmarks</code> instead, then recalibrate.</p>