[isaacsim.asset.importer.mjcf] Omniverse MJCF Importer

Version: 2.5.0

MJCF Importer

Enable Extension

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

Command-line interface

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

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

Experience/extension configuration

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

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

Extension Manager UI

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

MJCF Importer Extension [isaacsim.asset.importer.mjcf]

MJCF Import Commands

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

import omni.kit.commands
from pxr import UsdLux, Sdf, Gf, UsdPhysics, PhysicsSchemaTools

# setting up import configuration:
status, import_config = omni.kit.commands.execute("MJCFCreateImportConfig")
import_config.set_fix_base(True)
import_config.set_import_inertia_tensor(True)

# Get path to extension data:
ext_manager = omni.kit.app.get_app().get_extension_manager()
ext_id = ext_manager.get_enabled_extension_id("isaacsim.asset.importer.mjcf")
extension_path = ext_manager.get_extension_path(ext_id)

# import MJCF
omni.kit.commands.execute(
    "MJCFCreateAsset",
    mjcf_path=extension_path + "/data/mjcf/nv_ant.xml",
    import_config=import_config,
    prim_path="/ant"
)

# get stage handle
stage = omni.usd.get_context().get_stage()

# enable physics
scene = UsdPhysics.Scene.Define(stage, Sdf.Path("/physicsScene"))
# set gravity
scene.CreateGravityDirectionAttr().Set(Gf.Vec3f(0.0, 0.0, -1.0))
scene.CreateGravityMagnitudeAttr().Set(9.81)

# add lighting
distantLight = UsdLux.DistantLight.Define(stage, Sdf.Path("/DistantLight"))
distantLight.CreateIntensityAttr(500)

class MJCFCreateAsset(*args: Any, **kwargs: Any)

This command parses and imports a given mjcf file.

Parameters:

• arg0 (str) – The absolute path the mjcf file

• arg1 (isaacsim.asset.importer.mjcf._mjcf.ImportConfig) – Import configuration

• arg2 (str) – Path to the robot on the USD stage

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

class MJCFCreateImportConfig(*args: Any, **kwargs: Any)

Returns an ImportConfig object that can be used while parsing and importing. Should be used with the MJCFCreateAsset command

Returns:

Parsed MJCF stored in an internal structure.

Return type:

isaacsim.asset.importer.mjcf._mjcf.ImportConfig

This extension provides an interface to the MJCF importer.

Example

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

from isaacsim.asset.importer.mjcf import _mjcf
mjcf_interface = _mjcf.acquire_mjcf_interface()

# setup config params
import_config = _mjcf.ImportConfig()
import_config.fix_base = True

# parse and import file
mjcf_interface.create_asset_mjcf(mjcf_path, prim_path, import_config)

Refer to the sample documentation for more examples and usage

class Mjcf

create_asset_mjcf(

self: isaacsim.asset.importer.mjcf._mjcf.Mjcf,

fileName: str,

primName: str,

config: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

stage_identifier: str = '',

) → None

Parse and import MJCF file.

Parameters:

• arg0 (str) – The absolute path to the mjcf

• arg1 (str) – Path to the robot on the USD stage

• arg2 (isaacsim.asset.importer.mjcf._mjcf.ImportConfig) – Import configuration

• arg3 (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.

class ImportConfig

set_convex_decomp(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_create_body_for_fixed_joint(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_create_physics_scene(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_default_drive_strength(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: float,

) → None

set_density(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: float,

) → None

set_distance_scale(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: float,

) → None

set_fix_base(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_import_inertia_tensor(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_import_sites(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_instanceable_usd_path(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: str,

) → None

set_make_default_prim(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_make_instanceable(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_merge_fixed_joints(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_override_com(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_override_inertia(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_self_collision(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

set_visualize_collision_geoms(

self: isaacsim.asset.importer.mjcf._mjcf.ImportConfig,

arg0: bool,

) → None

property convex_decomp

Decompose a convex mesh into smaller pieces for a closer fit

property create_body_for_fixed_joint

creates body for fixed joint

property create_physics_scene

add a physics scene to the stage on import

property default_drive_strength

default drive stiffness used for joints

property density

default density used for links

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 mjcf, if not specified in mjcf it will import as identity

property instanceable_usd_path

USD file to store instanceable mehses in

property make_default_prim

set imported robot as default prim

property make_instanceable

Creates an instanceable version of the asset. All meshes will be placed in a separate USD file

property merge_fixed_joints

Consolidating links that are connected by fixed joints

property override_com

whether to compute the center of mass from geometry and override values given in the original asset

property override_inertia_tensor

Whether to compute the inertia tensor from geometry and override values given in the original asset

property self_collision

Self collisions between links in the articulation