SSG-48 gripper documentation

The documentation of the SSG-48 adaptive electric gripper by Source Robotics: the manual (safety, technical data, installation, setup, operation, firmware), the gripper's CAN and UART reference, and guides.

Read it at docs.source-robotics.com/SSG48-gripper-docs.

The hardware files are in Source-Robotics/SSG-48-adaptive-electric-gripper; the gripper runs the firmware of the Spectral Micro driver, Source-Robotics/Spectral-Micro-BLDC-controller.

What is in this repository

docs/	the pages: the manual chapters at the top level, build/, reference/, guides/, support/, appendix/
docs/build/bill-of-materials.md, docs/assets/bom/	written by tools/sync_bom.py from the gripper repository's BOM and its reference images. Never edit
docs/includes/	text shared by pages (glossary, symbols, abbreviations) and the data the reference pages are built from
docs/includes/can_commands.yml, uart_commands.yml	the hand-written descriptions of the CAN messages and UART commands a gripper needs (partial: true: the rest of the driver's commands are on the Spectral Micro site)
docs/includes/generated/	written by tools/sync_firmware.py from the firmware's release tag: firmware_facts.json, firmware_release_notes.md. Never edit
versions.yml	every version fact: the gripper release the site is versioned by, the firmware release it describes, the manual's number and revision
compatibility.yml	which firmware release works with which bootloader, gripper hardware, Python library and ROS 2 driver
hooks/	versions.py writes the version facts into the pages; firmware_pages.py builds the reference pages; llms.py writes the Markdown twin of every page, llms.txt and llms-full.txt
docs/assets/models/ssg48/	the 3D model of the configurator on the landing page, written by tools/build_model.py from the repository's URDF. Never edit
tools/	sync_firmware.py, sync_bom.py, build_model.py, test_tools.py, root_404.html
overrides/	the theme changes: the older-version banner, the edit/report line, the header's repository card

The site is built with MkDocs and the Material for MkDocs theme, in the same form as the [Spectral Micro](https://github.com/Source-Robotics/Spectral Micro-docs) and PAR6 documentation; the hooks and tools are the same files.

Preview it locally

You need Python 3.11 or newer.

git clone https://github.com/Source-Robotics/SSG48-gripper-docs.git
cd SSG48-gripper-docs
python -m venv .venv
.venv/Scripts/pip install -r requirements.txt      # Linux and macOS: .venv/bin/pip
mkdocs serve

Open http://127.0.0.1:8000/SSG48-gripper-docs/. The page reloads by itself when you save a file.

Every push and pull request runs python tools/test_tools.py and mkdocs build --strict, which fails on a broken link or a missing page. Run both before you open a pull request.

The reference is generated from the firmware

The command IDs, the frame lengths the firmware accepts, the responses it sends, the list of UART commands with their kind, argument type and what they print are read from the Spectral firmware's source at its release tag by tools/sync_firmware.py. The descriptions, units and byte layouts are written by hand in docs/includes/can_commands.yml and uart_commands.yml, for the commands a gripper needs. The build fails when the two disagree: a command the descriptions name and the firmware does not have, or a byte layout that does not fit the frame.

python tools/sync_firmware.py            # write docs/includes/generated/ from firmware.tag in versions.yml
python tools/sync_firmware.py --check    # exit 1 if they are out of date

The tool needs a clone of the Spectral firmware repository with its tags, next to this repository or named by --firmware PATH / FIRMWARE_DIR, and the network for the release notes (--no-network keeps the file that is there). The CI build does not run it; the generated files are committed.

The bill of materials is copied from the gripper repository

docs/build/bill-of-materials.md is the gripper repository's BOM, as it is, with its reference images shown inline: tools/sync_bom.py reads a clone of the repository named in versions.yml (--repo PATH, $GRIPPER_REPO_DIR, a sibling folder or ../../projects/<name>), converts the note blocks, copies and scales the images into docs/assets/bom/, and writes a header naming the commit it copied. A wrong part or a broken link is fixed in the repository's file, then:

python tools/sync_bom.py            # rewrite the page and the images from the clone
python tools/sync_bom.py --check    # exit 1 if the page is out of date

The 3D model, the Markdown twins and the feedback widget

tools/build_model.py builds docs/assets/models/ssg48/ from the gripper repository's URDF (the same --repo as the BOM tool; needs trimesh): the body, one file per finger option, and viewer.json. The landing and dimensions pages show them in the configurator docs/javascripts/gripper-viewer.js (three.js from a CDN, through the import map in overrides/main.html, loaded only on those pages): turn and zoom, open the jaws, choose the fingers and the colours. Run the tool again when the meshes change.

hooks/llms.py writes, at every build, a Markdown twin of every page next to its HTML (…/index.md), llms.txt (an index of the twins by tab) and llms-full.txt (every page in one file), with links pinned to the documented release (including when publishing with mike). The "Copy this page as Markdown" button in the page header reads the twin.

The "Was this page helpful?" widget at the end of every page is configured under extra.analytics.feedback. With provider: google (the shared Google Analytics property, loaded after the reader accepts the cookie banner of extra.consent), Material's own integration records the page views and sends each vote as an event named feedback. overrides/partials/integrations/analytics/custom.html is the alternative for a provider without cookies (Plausible, or a POST to an extra.feedback_endpoint): set provider: custom to use it.

Two more site features: the "Last update" date under every page comes from the git-revision-date-localized plugin (the page's last commit; the CI checks out the whole history for it), and comments through Giscus are wired in overrides/partials/comments.html and configured under extra.comments in mkdocs.yml (all the docs sites share one Discussions home, the hub repository; the landing page opts out with comments: false). The calculator on the Force and speed page is docs/javascripts/gripper-calculator.js, driven by the data attributes of its block.

The PDF of the manual

The print-site plugin (the last plugin in mkdocs.yml) builds one page with every chapter in order, a cover and a table of contents, at print_page/. hooks/pdf.py prints that page to site/assets/SSG-48-gripper-manual.pdf with headless Chrome when the environment variable DOCS_PDF is set, which the publish workflow does; a local build sets it on demand (DOCS_PDF=1 mkdocs build). While the hook is on, the page-help line of every page links the PDF.

Versions and releases

The site is versioned by gripper release: the version the product repository tags (V1.1, ...), published under that name (1.1, ...). The version selector in the site's header switches between releases, and a page of an older release says so in a bar at the top. The versions are built with mike and kept in the gh-pages branch; latest points at the newest.

The gripper runs the Spectral driver's firmware, and the pages describe one firmware release (the version box on the landing page names it). A new firmware release for the same gripper does not make a new version of the site: the pages are updated in place, with a new revision letter.

All version facts live in versions.yml, never in a page: docs_version (the gripper release, which is also the name the version is published under) with product.tag (V + docs_version), firmware.version with firmware.tag (V + firmware.version), and the manual's number, title, revision, status and publication date. hooks/versions.py writes them into the version box on the landing page and into the list of documents on the About page; a malformed or missing fact stops the build.

When the firmware releases a new version

1. Set firmware.version and firmware.tag in versions.yml; add a row to compatibility.yml, with the docs cell naming this site's version.
2. Run python tools/sync_firmware.py. If the firmware changed a gripper command, the build now fails until can_commands.yml / uart_commands.yml describe it: write the description.
3. Update the pages for what changed, using the release notes; give the manual a new revision letter in versions.yml and a line in its Document history on docs/about.md.
4. Commit and push to main. The site republishes the current version with the new firmware.

When the gripper releases a new version

1. Set docs_version, product.tag and product.released in versions.yml, and the manual's applies_to if the hardware the manual applies to changed.
2. Update the pages for what changed in the hardware; a new revision letter and a Document history line.
3. Commit and push to main. The site publishes the new version, latest moves to it, and the previous gripper release's pages stay as they were.

Publishing

.github/workflows/publish.yml publishes on every push to main: the tests, a strict build, then mike deploy for docs_version with the alias latest. In the repository's Settings, under Pages, the source must be "Deploy from a branch", branch gh-pages, folder / (root). Never run mkdocs gh-deploy on this repository: it would overwrite every version mike keeps there.

The root of gh-pages also carries 404.html (source: tools/root_404.html). It forwards addresses from before the versioning, such as /SSG48-gripper-docs/page3_control/, to the same page under latest/, where the redirects plugin in mkdocs.yml maps the old page names to the new pages. To preview the published versions locally, with the version selector, run mike serve.

The site's address

The site is served at https://docs.source-robotics.com/SSG48-gripper-docs/: the organisation's docs domain plus this repository's name. Never rename this repository (its address would change and GitHub does not forward the old one), and never add a CNAME file or a custom domain to it (that would take it out of the shared domain).

License

• Text and images: Creative Commons Attribution-ShareAlike 4.0, see LICENSE. You may copy, adapt and share them, also commercially, if you credit Source Robotics and share your changes under the same license.
• Code: the MIT license. This covers the code examples in the pages and the site's own code (hooks, tools, overrides, scripts), so you can use an example in your own program without other conditions.
• Names and logos: the Source Robotics name, the product names and the logos are not covered by either license. The gripper's hardware design is licensed separately, in the product repository.

By contributing you agree that your contribution is published under these licenses.

Contributing

A small fix can be made from the browser: every page ends with a link to edit it on GitHub. For anything larger, open an issue first, then a pull request. The Contributing page on the site has the house rules. Questions about the gripper itself go to the product repository's issue tracker.

Checking the page features

python tools/test_site_features.py checks release-pinned Markdown asset links, the prefilled issue body, and the syntax of Python examples without running them or connecting to hardware. The CI build runs it.

hooks/can_tools.py generates the firmware-specific JSON/DBC downloads and the CAN frame tool from the same can_commands.yml and tagged firmware facts as the reference. Keep the hook, browser codec and tests in step across the four driver/gripper sites. The gripper status pair marks bit_order: lsb_first explicitly; do not replace it with normal big-endian bit ordering.

Run python tools/test_can_tools.py for the schema, DBC and known wire vectors (Node.js runs the browser codec without a browser). With cantools==40.7.1 installed, it also loads and decodes the DBC independently; the CI build installs this test dependency. DBC cannot select a command layout from its DLC, so the driver sites ship separate position, velocity and current files. Never merge those into a single invented wire layout.

Motor GUI screenshots under docs/assets/motor-gui/ were captured from the live tool on 2026-10-31. The captions distinguish the real connection screen from simulated CAN hardware. Numbered annotations are HTML/CSS over the original capture; refresh the captures and captions when the controls change.