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Python API#

RobotAssembler

RobotAssembler is a class to assemble robots from a base robot and an attachment robot.

AssembledRobot

A wrapper class providing convenient access to assembled robot body information.

AssembledBodies

Class representing two assembled rigid bodies connected by a fixed joint.

class RobotAssembler#

Bases: object

RobotAssembler is a class to assemble robots from a base robot and an attachment robot. It will create a new USD stage with the assembly and configure a variant selection to enable the attachment robot to be selected.

If the variant set already exists in the source asset, it creates a new entry to it, otherwise it creates a new variant set.

assemble() → None#

Composes the attachment robot onto the base robot, so that the attachment robot is a child of the base robot, and ready to simulate.

begin_assembly(
stage: object,
base_prim_path: str,
base_mount_path: str,
attachment_prim_path: str,
attachment_mount_path: str,
variant_set: str,
variant_name: str,
) → None#

Start the robot assembly process.

Places the attachment robot relative to the base robot but does not compose them yet.

Parameters:

  • stage – USD stage for assembly

  • base_prim_path – Path to base robot prim

  • base_mount_path – Path to mount frame on base robot

  • attachment_prim_path – Path to attachment robot prim

  • attachment_mount_path – Path to mount frame on attachment robot

  • variant_set – Name of variant set to create/modify

  • variant_name – Name of variant to create

cancel_assembly() → None#

Cancel the current assembly operation and reset state.

finish_assemble() → None#

Finalize the assembly process by configuring variant sets and saving the assembly to a USD file.

get_articulation_root_api_path(prim_path: str) → str#

Get the prim path that has the Articulation Root API applied.

Parameters:

prim_path – Path to a prim

Returns:

Path to the prim that has the Articulation Root API applied

is_root_joint(prim: object) → bool#

Check if a prim is a root joint (has no body0 or body1 target).

Parameters:

prim – Prim to check

Returns:

True if prim is a root joint, False otherwise

mask_collisions(
prim_path_a: str,
prim_path_b: str,
) → pxr.Usd.Relationship#

Mask collisions between two prims. All nested prims will also be included.

Parameters:

  • prim_path_a – Path to a prim

  • prim_path_b – Path to a prim

Returns:

A relationship filtering collisions between prim_path_a and prim_path_b

reset() → None#

Reset the assembler to its initial state.

Performs three responsibilities:

  1. If an assembly is in progress (self._status == AssemblyStatus.ASSEMBLING) cancels it via cancel_assembly().

  2. Clears the references to the active stage and to the base/attachment robot and mount prim paths.

  3. Initializes the assembly-sublayer bookkeeping fields (_assembly_identifier, _local_assembly_identifier, _assembly_layer, _direct_edit, _variant_set, _variant_name) to safe defaults so that cancel_assembly() remains valid to call on a fresh or already-reset instance.

class AssembledRobot(
assembled_robots: AssembledBodies,
)#

Bases: object

A wrapper class providing convenient access to assembled robot body information.

This class serves as a high-level interface for interacting with assembled robots, encapsulating the underlying AssembledBodies instance and exposing its key properties through a simplified API. It provides direct access to robot paths, joint information, and collision masking relationships for assembled robot configurations.

The class acts as a facade over AssembledBodies, making it easier to work with assembled robot data without needing to interact directly with the lower-level assembly implementation.

Parameters:

assembled_robots – The AssembledBodies instance containing the robot assembly data.

property attach_path: str#

Prim path of the floating (attach) body.

Returns:

Prim path of the floating (attach) body.

property base_path: str#

Prim path of the base body.

Returns:

Prim path of the base body.

property collision_mask: pxr.Usd.Relationship#

A Usd Relationship masking collisions between the two assembled robots.

Returns:

A Usd Relationship masking collisions between the two assembled robots.

property fixed_joint: pxr.UsdPhysics.FixedJoint#

USD fixed joint linking base and floating body together.

Returns:

USD fixed joint linking base and floating body together.

property root_joints: list[pxr.UsdPhysics.Joint]#

Root joints that tie the floating body to the USD stage. These are disabled in an assembled body,.

and will be re-enabled by the disassemble() function.

Returns:

Root joints that tie the floating body to the USD stage.

class AssembledBodies(
base_path: str,
attach_path: str,
fixed_joint: pxr.UsdPhysics.FixedJoint,
root_joints: list[pxr.UsdPhysics.Joint],
attach_body_articulation_root: pxr.Usd.Prim,
collision_mask: object = None,
)#

Bases: object

Class representing two assembled rigid bodies connected by a fixed joint.

This class maintains references to the base and attach bodies, the fixed joint connecting them, and provides methods to manipulate their relative transform.

Parameters:

  • base_path – Prim path of the base body.

  • attach_path – Prim path of the attach body.

  • fixed_joint – Fixed joint connecting the bodies.

  • root_joints – Root joints of the attach body.

  • attach_body_articulation_root – Articulation root of attach body.

  • collision_mask – Collision mask between bodies.

property attach_body_articulation_root: pxr.Usd.Prim#

USD articulation root of the floating body.

Returns:

USD articulation root of the floating body.

property attach_path: str#

Prim path of the floating (attach) body.

Returns:

Prim path of the floating (attach) body.

property base_path: str#

Prim path of the base body.

Returns:

Prim path of the base body.

property collision_mask: pxr.Usd.Relationship#

A Usd Relationship masking collisions between the two assembled bodies.

Returns:

A Usd Relationship masking collisions between the two assembled bodies.

property fixed_joint: pxr.UsdPhysics.FixedJoint#

USD fixed joint linking base and floating body together.

Returns:

USD fixed joint linking base and floating body together.

property root_joints: list[pxr.UsdPhysics.Joint]#

Root joints that tie the floating body to the USD stage. These are disabled in an assembled body,.

and will be re-enabled by the disassemble() function.

Returns:

Root joints that tie the floating body to the USD stage.