onshnap

onshnap exports Onshape assemblies as static URDF or MJCF files with STL meshes. Takes a frozen snapshot of the assembly and exports it as a fixed robot description file.

Specifically, it exports assemblies as static robot descriptions (no kinematic chains) with star topology (all parts connected to a single base_link via fixed joints).

It also supports exporting to MJCF if you want to do that for some reason.

Usage

First install the package:

pip install onshnap

Then set your Onshape API keys in your environment and run the export:

export ONSHAPE_ACCESS_KEY="your-access-key"
export ONSHAPE_SECRET_KEY="your-secret-key"
onshnap /path/to/directory/with/config

To find where to get your Onshape API keys, see the Onshape Help Center.

Configuration

The config.json should contain:

{
    "url": "https://cad.onshape.com/documents/...",
    "filetype": "urdf", // optional, defaults to "urdf"
    "output_name": "onshnap", // optional, defaults to "onshnap"
    "mesh_dir": "meshes", // optional, defaults to "meshes"
    "units": "meter", // optional, defaults to "meter"
    "create_centroid_links": true // optional, defaults to false
}

Configuration Options:

• url (required): Onshape document URL
• filetype (optional): Output format - "urdf" (default) or "mjcf"
• output_name (optional): Base name for output files (default: "onshnap")
• mesh_dir (optional): Subdirectory name for mesh files (default: "meshes")
• units (optional): Units for mesh export - "meter" (default) or "inch"
• create_centroid_links (optional): If True, create virtual links at center of mass (default: false)