MuJoCo Standard Articulation Root#

Code

MUJOCO.BA.001

Validator

CheckPrim

Compatibility

other

Tags

🔑

Summary#

MuJoCo articulations must use standard UsdPhysics.ArticulationRootAPI and must not author unsupported MuJoCo-specific articulation-root schemas.

Description#

The official MuJoCo USD schema defines MuJoCo scene, collider, mesh-collider, site, joint, actuator, equality, and tendon schemas, but it does not define a MjcArticulationRootAPI or MjcArticulationRoot prim type. MuJoCo articulation roots therefore remain standard USD physics articulation roots.

For a MuJoCo-ready base articulation:

  • the Standard base-articulation feature supplies the required single UsdPhysics.ArticulationRootAPI

  • no prim may apply MjcArticulationRootAPI

  • no prim may use the MjcArticulationRoot type

Why is it required?#

  • Prevents assets from depending on an invented MuJoCo articulation-root schema.

  • Keeps MuJoCo robot articulation authoring aligned with official MuJoCo USD.

  • Lets MuJoCo-specific joint, actuator, collision, and scene data layer around standard USD articulation topology.

Examples#

# Valid: standard USD articulation root.
def Xform "Robot" (
    prepend apiSchemas = ["PhysicsArticulationRootAPI"]
)
{
}

# Invalid: invented MuJoCo articulation-root API.
def Xform "Robot" (
    prepend apiSchemas = ["PhysicsArticulationRootAPI", "MjcArticulationRootAPI"]
)
{
}

How to comply#

  • Apply PhysicsArticulationRootAPI to the single intended articulation root.

  • Do not author MjcArticulationRootAPI.

  • Do not create MjcArticulationRoot prims.

  • Put MuJoCo runtime data on the supported MuJoCo schemas, such as MjcSceneAPI, MjcJointAPI, MjcActuator, and collider/site APIs.

For More Information#