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Pre-import validation and auto-fix for URDF files targeting Isaac Sim / USD
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Based on SOC occupation classification
| name | URDF Validator & Fixer |
| description | Pre-import validation and auto-fix for URDF files targeting Isaac Sim / USD |
Validate and fix URDF files before importing into Isaac Sim. Catches USD naming violations, duplicate materials, unbounded joint limits, missing inertial properties, and broken mesh references — problems that otherwise cause silent import failures.
Follow this sequence for best results:
Get a structural overview of the robot model.
urdf_inspect(file_path="/path/to/robot.urdf")
Review: link/joint counts, kinematic tree, mass distribution, mesh files.
Check for all known issues.
urdf_validate(file_path="/path/to/robot.urdf")
Review: issues by severity (error > warning > info) and category.
Auto-fix what can be fixed.
urdf_fix(
file_path="/path/to/robot.urdf",
output_path="/path/to/robot_fixed.urdf"
)
The original file is never modified. Check name_mapping in the result — if links or joints were renamed, downstream code (controllers, configs) needs updating too.
Confirm fixes resolved the issues.
urdf_validate(file_path="/path/to/robot_fixed.urdf")
Expect zero errors for fixed categories. Remaining warnings (e.g., missing collision geometry, package:// URIs) may need manual attention.
urdf_validate| Parameter | Type | Default | Description |
|---|---|---|---|
file_path | str | None | Path to URDF file |
urdf_string | str | None | URDF XML as string |
categories | list[str] | all | Filter: usd_naming, materials, joint_limits, inertial, collision, mesh_references |
min_severity | str | "info" | Minimum: error, warning, info |
urdf_fix| Parameter | Type | Default | Description |
|---|---|---|---|
file_path | str | None | Path to URDF file |
urdf_string | str | None | URDF XML as string |
output_path | str | auto | Output file path (default: *_fixed.urdf) |
fix_categories | list[str] | all | usd_naming, materials, joint_limits, inertial |
default_mass | float | 0.1 | Default mass (kg) for missing inertial |
default_inertia | float | 0.001 | Default diagonal inertia value |
max_joint_position | float | 2π | Replace ±inf position limits |
max_joint_velocity | float | π | Default velocity limit (rad/s) |
max_joint_effort | float | 100.0 | Default effort limit (Nm) |
urdf_inspect| Parameter | Type | Default | Description |
|---|---|---|---|
file_path | str | None | Path to URDF file |
urdf_string | str | None | URDF XML as string |
| Category | What it checks | Auto-fixable? |
|---|---|---|
usd_naming | Hyphens, dots, spaces, leading digits in link/joint/material names | Yes — renames + updates all references |
materials | Duplicate definitions with different RGBA, missing textures, JPEG warnings | Yes — deduplicates by appending suffix |
joint_limits | Infinite limits, missing effort/velocity, missing <limit> element | Yes — clamps to configurable defaults |
inertial | Missing <inertial>, zero/negative mass, zero inertia tensor | Yes — adds configurable defaults |
collision | Visual geometry without corresponding collision geometry | No — requires manual modeling |
mesh_references | Nonexistent mesh files, package:// URIs | No — mesh files must exist on disk |
<inertial> may be silently skipped or cause physics instability.package:// URIs won't resolve: Isaac Sim doesn't have ROS package resolution. Convert to relative or absolute paths.merge_fixed_joints = False in import config.name_mapping output.After fixing, verify the import works in Isaac Sim:
/path/to/isaacsim/python.sh scripts/verify_urdf_isaac_sim.py \
--original /path/to/robot.urdf \
--fixed /path/to/robot_fixed.urdf
This script imports both URDFs headless, checks prim paths, joints, articulation, and runs physics steps to verify stability.
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