[isaacsim.asset.importer.urdf] Urdf Importer Extension#

Version: 2.4.19

URDF Importer

Preview

Enable Extension#

The extension can be enabled (if not already) in one of the following ways:

Define the next entry as an application argument from a terminal.

APP_SCRIPT.(sh|bat) --enable isaacsim.asset.importer.urdf

Define the next entry under [dependencies] in an experience (.kit) file or an extension configuration (extension.toml) file.

[dependencies]
"isaacsim.asset.importer.urdf" = {}

Open the Window > Extensions menu in a running application instance and search for isaacsim.asset.importer.urdf. Then, toggle the enable control button if it is not already active.

URDF Import Extension [isaacsim.asset.importer.urdf]#

URDF Import Commands#

The following commands can be used to simplify the import process. Below is a sample demonstrating how to import the Carter URDF included with this extension

 1import omni.kit.commands
 2from pxr import UsdLux, Sdf, Gf, UsdPhysics, PhysicsSchemaTools
 3
 4# setting up import configuration:
 5status, import_config = omni.kit.commands.execute("URDFCreateImportConfig")
 6import_config.merge_fixed_joints = False
 7import_config.convex_decomp = False
 8import_config.import_inertia_tensor = True
 9import_config.fix_base = False
10import_config.collision_from_visuals = False
11
12# Get path to extension data:
13ext_manager = omni.kit.app.get_app().get_extension_manager()
14ext_id = ext_manager.get_enabled_extension_id("isaacsim.asset.importer.urdf")
15extension_path = ext_manager.get_extension_path(ext_id)
16# import URDF
17omni.kit.commands.execute(
18    "URDFParseAndImportFile",
19    urdf_path=extension_path + "/data/urdf/robots/carter/urdf/carter.urdf",
20    import_config=import_config,
21)
22# get stage handle
23stage = omni.usd.get_context().get_stage()
24
25# enable physics
26scene = UsdPhysics.Scene.Define(stage, Sdf.Path("/physicsScene"))
27# set gravity
28scene.CreateGravityDirectionAttr().Set(Gf.Vec3f(0.0, 0.0, -1.0))
29scene.CreateGravityMagnitudeAttr().Set(9.81)
30
31# add ground plane
32PhysicsSchemaTools.addGroundPlane(stage, "/World/groundPlane", "Z", 1500, Gf.Vec3f(0, 0, -50), Gf.Vec3f(0.5))
33
34# add lighting
35distantLight = UsdLux.DistantLight.Define(stage, Sdf.Path("/DistantLight"))
36distantLight.CreateIntensityAttr(500)
class URDFCreateImportConfig(*args: Any, **kwargs: Any)#

Returns an ImportConfig object that can be used while parsing and importing. Should be used with URDFParseFile and URDFParseAndImportFile commands

Returns:

Parsed URDF stored in an internal structure.

Return type:

isaacsim.asset.importer.urdf._urdf.ImportConfig

class URDFImportRobot(*args: Any, **kwargs: Any)#

This command parses and imports a given urdf and returns a UrdfRobot object

Parameters:

  • arg0 (str) – The absolute path to where the urdf file is

  • arg1 (UrdfRobot) – The parsed URDF Robot

  • arg2 (isaacsim.asset.importer.urdf._urdf.ImportConfig) – Import Configuration

  • arg3 (str) – destination path for robot usd. Default is “” which will load the robot in-memory on the open stage.

  • arg4 (bool) – if True, return the articulation Root prim path instead of the object’s base path.

Returns:

Path to the robot on the USD stage.

Return type:

str

class URDFParseAndImportFile(*args: Any, **kwargs: Any)#

This command parses and imports a given urdf and returns a UrdfRobot object

Parameters:

  • arg0 (str) – The absolute path to where the urdf file is

  • arg1 (isaacsim.asset.importer.urdf._urdf.ImportConfig) – Import Configuration

  • arg2 (str) – destination path for robot usd. Default is “” which will load the robot in-memory on the open stage.

  • arg3 (bool) – if True, return the articulation Root prim path instead of the object’s base path.

Returns:

Path to the robot on the USD stage.

Return type:

str

class URDFParseFile(*args: Any, **kwargs: Any)#

This command parses a given urdf and returns a UrdfRobot object

Parameters:
Returns:

Parsed URDF stored in an internal structure.

Return type:

isaacsim.asset.importer.urdf._urdf.UrdfRobot

class URDFParseText(*args: Any, **kwargs: Any)#

This command parses a given urdf and returns a UrdfRobot object

Parameters:
Returns:

Parsed URDF stored in an internal structure.

Return type:

isaacsim.asset.importer.urdf._urdf.UrdfRobot

This extension provides an interface to the URDF importer.

Example

Setup the configuration parameters before importing. Files must be parsed before imported.

>>> import omni
>>> import os
>>> from isaacsim.asset.importer.urdf import _urdf
>>> urdf_interface = _urdf.acquire_urdf_interface()
>>>
>>> # setup config params
>>> import_config = _urdf.ImportConfig()
>>> import_config.set_merge_fixed_joints(False)
>>> import_config.set_fix_base(True)
>>>
>>> # parse and import file
>>> ext_manager = omni.kit.app.get_app().get_extension_manager()
>>> ext_id = ext_manager.get_enabled_extension_id("isaacsim.asset.importer.urdf")
>>> extension_path = ext_manager.get_extension_path(ext_id)
>>> urdf_path = os.path.abspath(
...     extension_path + "/data/urdf/robots/franka_description/robots/"
... )
>>> filename = "panda_arm_hand.urdf"
>>> imported_robot = urdf_interface.parse_urdf(urdf_path, filename, import_config)
>>> urdf_interface.import_robot(urdf_path, filename, imported_robot, import_config, "")
'/panda'

Refer to the sample documentation for more examples and usage

class Urdf#
compute_natural_stiffness(
self: isaacsim.asset.importer.urdf._urdf.Urdf,
arg0: isaacsim.asset.importer.urdf._urdf.UrdfRobot,
arg1: str,
arg2: float,
) → float#

Compute the natural stiffness of a joint.

Parameters:

  • arg0 (isaacsim.asset.importer.urdf._urdf.UrdfRobot) – The parsed URDF, the output from parse_urdf

  • arg1 (str) – The name of the joint

  • arg2 (float) – The natural frequency of the joint

Returns:

The natural stiffness of the joint

Return type:

float

get_kinematic_chain(
self: isaacsim.asset.importer.urdf._urdf.Urdf,
arg0: isaacsim.asset.importer.urdf._urdf.UrdfRobot,
) → dict#

Get the kinematic chain of the robot. Mostly used for graphic display of the kinematic tree.

Parameters:

arg0 (isaacsim.asset.importer.urdf._urdf.UrdfRobot) – The parsed URDF, the output from parse_urdf

Returns:

A dictionary with information regarding the parent-child relationship between all the links and joints

Return type:

dict

import_robot(
self: isaacsim.asset.importer.urdf._urdf.Urdf,
assetRoot: str,
assetName: str,
robot: isaacsim.asset.importer.urdf._urdf.UrdfRobot,
importConfig: isaacsim.asset.importer.urdf._urdf.ImportConfig,
stage: str = '',
getArticulationRoot: bool = False,
) → str#

Importing the robot, from the already parsed URDF file.

Parameters:

  • arg0 (str) – The absolute path to where the urdf file is

  • arg1 (str) – The name of the urdf file

  • arg2 (isaacsim.asset.importer.urdf._urdf.UrdfRobot) – The parsed URDF file, the output from parse_urdf

  • arg3 (isaacsim.asset.importer.urdf._urdf.ImportConfig) – Import configuration parameters

  • arg4 (str) – optional: path to stage to use for importing. leaving it empty will import on open stage. If the open stage is a new stage, textures will not load.

Returns:

Path to the robot on the USD stage.

Return type:

str

parse_string_urdf(
self: isaacsim.asset.importer.urdf._urdf.Urdf,
arg0: str,
arg1: isaacsim.asset.importer.urdf._urdf.ImportConfig,
) → isaacsim.asset.importer.urdf._urdf.UrdfRobot#

Parse URDF file into the internal data structure, which is displayed in the importer window for inspection.

Parameters:
Returns:

Parsed URDF stored in an internal structure.

Return type:

isaacsim.asset.importer.urdf._urdf.UrdfRobot

parse_urdf(
self: isaacsim.asset.importer.urdf._urdf.Urdf,
arg0: str,
arg1: str,
arg2: isaacsim.asset.importer.urdf._urdf.ImportConfig,
) → isaacsim.asset.importer.urdf._urdf.UrdfRobot#

Parse URDF file into the internal data structure, which is displayed in the importer window for inspection.

Parameters:
Returns:

Parsed URDF stored in an internal structure.

Return type:

isaacsim.asset.importer.urdf._urdf.UrdfRobot

class ImportConfig#
set_collision_from_visuals(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_convex_decomp(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_create_physics_scene(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_default_drive_strength(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: float,
) → None#
set_default_drive_type(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: int,
) → None#
set_default_position_drive_damping(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: float,
) → None#
set_density(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: float,
) → None#
set_distance_scale(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: float,
) → None#
set_fix_base(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_import_inertia_tensor(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_make_default_prim(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_merge_fixed_joints(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_override_joint_dynamics(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_parse_mimic(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_replace_cylinders_with_capsules(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_self_collision(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: bool,
) → None#
set_subdivision_scheme(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: int,
) → None#
set_up_vector(
self: isaacsim.asset.importer.urdf._urdf.ImportConfig,
arg0: float,
arg1: float,
arg2: float,
) → None#
property collision_from_visuals#

Generate convex collision from the visual meshes.

property convex_decomp#

Decompose a convex mesh into smaller pieces for a closer fit

property create_physics_scene#

add a physics scene to the stage on import if none exists

property default_drive_strength#

default drive stiffness used for joints if drive type is position or velocity and none is authored

property default_drive_type#

default drive type used for joints

property default_position_drive_damping#

default drive damping used if drive type is set to position and no damping is authored

property density#

default density used for links, use 0 to autocompute

property distance_scale#

Set the unit scaling factor, 1.0 means meters, 100.0 means cm

property fix_base#

Create fix joint for base link

property import_inertia_tensor#

Import inertia tensor from urdf, if not specified in urdf it will import as identity

property make_default_prim#

set imported robot as default prim

property merge_fixed_joints#

Consolidating links that are connected by fixed joints

property override_joint_dynamics#

Use default values for all joints

property parse_mimic#

Parse Mimic Joint flag using PhysX Tendons

property replace_cylinders_with_capsules#

Replace all cylinder bodies in the URDF with capsules.

property self_collision#

Self collisions between links in the articulation

property subdivision_scheme#

Subdivision scheme to be used for mesh normals

property up_vector#

Up vector used for import

Settings#

Other Settings#

The extension changes some settings of the application or other extensions, which are listed in the table below.

Application/extension setting

Description

Value

exts."omni.kit.window.filepicker".detail_width_init

Set the initial width of the file picker to 390

390

exts."omni.kit.window.filepicker".detail_width_min

Set the minimum width of the file picker to 390

390

exts."omni.kit.window.filepicker".detail_width_max

Set the maximum width of the file picker to 600

600