scripts/tools/convert_urdf.py

# Copyright (c) 2022-2026, The Isaac Lab Project Developers (https://github.com/isaac-sim/IsaacLab/blob/main/CONTRIBUTORS.md).
# All rights reserved.
#
# SPDX-License-Identifier: BSD-3-Clause

"""
Utility to convert a URDF into USD format.

Unified Robot Description Format (URDF) is an XML file format used in ROS to describe all elements of
a robot. For more information, see: http://wiki.ros.org/urdf

This script uses the URDF importer extension from Isaac Sim (``isaacsim.asset.importer.urdf``) to convert a
URDF asset into USD format. It is designed as a convenience script for command-line use. For more
information on the URDF importer, see the documentation for the extension:
https://docs.isaacsim.omniverse.nvidia.com/latest/robot_setup/ext_isaacsim_asset_importer_urdf.html


positional arguments:
  input               The path to the input URDF file.
  output              The path to store the USD file.

optional arguments:
  -h, --help                Show this help message and exit
  --merge-joints            Consolidate links that are connected by fixed joints. (default: False)
  --fix-base                Fix the base to where it is imported. (default: False)
  --joint-stiffness         The stiffness of the joint drive. (default: 100.0)
  --joint-damping           The damping of the joint drive. (default: 1.0)
  --joint-target-type       The type of control to use for the joint drive. (default: "position")

"""

"""Launch Isaac Sim Simulator first."""

import argparse

from isaaclab.app import AppLauncher

# add argparse arguments
parser = argparse.ArgumentParser(description="Utility to convert a URDF into USD format.")
parser.add_argument("input", type=str, help="The path to the input URDF file.")
parser.add_argument("output", type=str, help="The path to store the USD file.")
parser.add_argument(
    "--merge-joints",
    action="store_true",
    default=False,
    help="Consolidate links that are connected by fixed joints.",
)
parser.add_argument("--fix-base", action="store_true", default=False, help="Fix the base to where it is imported.")
parser.add_argument(
    "--joint-stiffness",
    type=float,
    default=100.0,
    help="The stiffness of the joint drive.",
)
parser.add_argument(
    "--joint-damping",
    type=float,
    default=1.0,
    help="The damping of the joint drive.",
)
parser.add_argument(
    "--joint-target-type",
    type=str,
    default="position",
    choices=["position", "velocity", "none"],
    help="The type of control to use for the joint drive.",
)

# append AppLauncher cli args
AppLauncher.add_app_launcher_args(parser)
# parse the arguments
args_cli = parser.parse_args()

# launch omniverse app
app_launcher = AppLauncher(args_cli)
simulation_app = app_launcher.app

"""Rest everything follows."""

import contextlib
import os

import carb
import omni.kit.app

import isaaclab.sim as sim_utils
from isaaclab.sim.converters import UrdfConverter, UrdfConverterCfg
from isaaclab.utils.assets import check_file_path
from isaaclab.utils.dict import print_dict


def main():
    # check valid file path
    urdf_path = args_cli.input
    if not os.path.isabs(urdf_path):
        urdf_path = os.path.abspath(urdf_path)
    if not check_file_path(urdf_path):
        raise ValueError(f"Invalid file path: {urdf_path}")
    # create destination path
    dest_path = args_cli.output
    if not os.path.isabs(dest_path):
        dest_path = os.path.abspath(dest_path)

    # Create Urdf converter config
    urdf_converter_cfg = UrdfConverterCfg(
        asset_path=urdf_path,
        usd_dir=os.path.dirname(dest_path),
        usd_file_name=os.path.basename(dest_path),
        fix_base=args_cli.fix_base,
        merge_fixed_joints=args_cli.merge_joints,
        force_usd_conversion=True,
        joint_drive=UrdfConverterCfg.JointDriveCfg(
            gains=UrdfConverterCfg.JointDriveCfg.PDGainsCfg(
                stiffness=args_cli.joint_stiffness,
                damping=args_cli.joint_damping,
            ),
            target_type=args_cli.joint_target_type,
        ),
    )

    # Print info
    print("-" * 80)
    print("-" * 80)
    print(f"Input URDF file: {urdf_path}")
    print("URDF importer config:")
    print_dict(urdf_converter_cfg.to_dict(), nesting=0)
    print("-" * 80)
    print("-" * 80)

    # Create Urdf converter and import the file
    urdf_converter = UrdfConverter(urdf_converter_cfg)
    # print output
    print("URDF importer output:")
    print(f"Generated USD file: {urdf_converter.usd_path}")
    print("-" * 80)
    print("-" * 80)

    # Determine if there is a GUI to update:
    # acquire settings interface
    carb_settings_iface = carb.settings.get_settings()
    # read flag for whether a local GUI is enabled
    local_gui = carb_settings_iface.get("/app/window/enabled")
    # read flag for whether livestreaming GUI is enabled
    livestream_gui = carb_settings_iface.get("/app/livestream/enabled")

    # Simulate scene (if not headless)
    if local_gui or livestream_gui:
        # Open the stage with USD
        sim_utils.open_stage(urdf_converter.usd_path)
        # Reinitialize the simulation
        app = omni.kit.app.get_app_interface()
        # Run simulation
        with contextlib.suppress(KeyboardInterrupt):
            while app.is_running():
                # perform step
                app.update()


if __name__ == "__main__":
    # run the main function
    main()
    # close sim app
    simulation_app.close()