[isaacsim.robot_setup.assembler] Robot Assembler

Version: 2.1.5

Alpha version of Robot Assembler Extension: Assemble multiple Articulations into a single robot

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.robot_setup.assembler

Experience/extension configuration

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

[dependencies]
"isaacsim.robot_setup.assembler" = {}

Extension Manager UI

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

API

Python API

RobotAssembler
AssembledRobot
AssembledBodies

class RobotAssembler

Bases: object

static move_articulation_root(src_prim, dst_prim)

Move the articulation root from src to dst.

This function is deprecated in favor of isaacsim.core.utils.articulations.move_articulation_root() and will be removed in a future release.

is_root_joint(prim)

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 (str) – Path to a prim

• prim_path_b (str) – Path to a prim

Returns:

A relationship filtering collisions between prim_path_a and prim_path_b

Return type:

Usd.Relationship

assemble_rigid_bodies(

base_path: str,

attach_path: str,

base_mount_frame: str,

attach_mount_frame: str,

fixed_joint_offset: array = array([0., 0., 0.]),

fixed_joint_orient: array = array([1, 0, 0, 0]),

mask_all_collisions: bool = True,

) → AssembledBodies

Assemble two rigid bodies into one physical structure

Parameters:

• base_robot_path (str) – Path to base robot.

• attach_robot_path (str) – Path to attach robot. The attach robot will be unrooted from the stage and attached only to the base robot

• base_robot_mount_frame (str) – Relative path to frame in base robot where there is the desired attach point.

• attach_robot_mount_frame (str) – Relative path to frame in the attach robot where there is the desired attach point.

• fixed_joint_offset (np.array, optional) – Fixed offset between attach points. Defaults to np.zeros(3).

• fixed_joint_orient (np.array, optional) – Fixed orientation between attach points. Defaults to np.array([1, 0, 0, 0]).

• mask_all_collisions (bool, optional) – Mask all collisions between attach robot and base robot. This is necessary when setting single_robot=False to prevent Physics constraint violations from the new fixed joint. Advanced users may set this flag to False and use the mask_collisions() function separately for more customizable behavior. Defaults to True.

Returns:

An object representing the assembled bodies. This object can detach the composed robots and edit the fixed joint transform.

Return type:

AssembledBodies

assemble_articulations(

base_robot_path: str,

attach_robot_path: str,

base_robot_mount_frame: str,

attach_robot_mount_frame: str,

fixed_joint_offset: array = array([0., 0., 0.]),

fixed_joint_orient: array = array([1, 0, 0, 0]),

mask_all_collisions=True,

single_robot=False,

) → AssembledRobot

Compose two robots into one physical structure

Parameters:

• base_robot_path (str) – Path to base robot.

• attach_robot_path (str) – Path to attach robot. The attach robot will be unrooted from the stage and attached only to the base robot

• base_robot_mount_frame (str) – Relative path to frame in base robot where there is the desired attach point.

• attach_robot_mount_frame (str) – Relative path to frame in the attach robot where there is the desired attach point.

• fixed_joint_offset (np.array, optional) – Fixed offset between attach points. Defaults to np.zeros(3).

• fixed_joint_orient (np.array, optional) – Fixed orientation between attach points. Defaults to np.array([1, 0, 0, 0]).

• mask_all_collisions (bool, optional) – Mask all collisions between attach robot and base robot. This is necessary when setting single_robot=False to prevent Physics constraint violations from the new fixed joint. Advanced users may set this flag to False and use the mask_collisions() function separately for more customizable behavior. Defaults to True.

• single_robot (bool, optional) – If True: control the resulting composed robots as a single robot Articulation at base_robot_path. Setting this flag to True may resolve unstable physics behavior when teleporting the robot base. Defaults to False.

Returns:

An object representing the assembled robot. This object can detach the composed robots and edit the fixed joint transform.

Return type:

AssembledRobot

create_fixed_joint(

prim_path: str,

target0: str | None = None,

target1: str | None = None,

fixed_joint_offset: array = array([0., 0., 0.]),

fixed_joint_orient: array = array([1, 0, 0, 0]),

) → pxr.UsdPhysics.FixedJoint

Create a fixed joint between two bodies

Parameters:

• prim_path (str) – Prim path at which to place new fixed joint.

• target0 (str, optional) – Prim path of frame at which to attach fixed joint. Defaults to None.

• target1 (str, optional) – Prim path of frame at which to attach fixed joint. Defaults to None.

• fixed_joint_offset (np.array, optional) – Translational offset of fixed joint between frames. Defaults to np.zeros(3).

• fixed_joint_orient (np.array, optional) – Rotational offset of fixed joint between frames (quaternion). Defaults to np.array([1, 0, 0, 0]).

Returns:

A USD fixed joint

Return type:

UsdPhysics.FixedJoint

convert_prim_to_rigid_body(prim_path: str) → None

Convert a prim to a rigid body by applying the UsdPhysics.RigidBodyAPI Also sets physics:kinematicEnabled property to true to prevent falling from gravity without needing a fixed joint.

Parameters:

prim_path (str) – Path to prim to convert.

class AssembledRobot(

assembled_robots: AssembledBodies,

)

Bases: object

property base_path: str

Prim path of the base body

Returns:

Prim path of the base body

Return type:

str

property attach_path: str

Prim path of the floating (attach) body

Returns:

Prim path of the floating (attach) body

Return type:

str

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

Return type:

UsdPhysics.FixedJoint

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.

Return type:

List[UsdPhysics.Joint]

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

Return type:

Usd.Relationship

is_assembled() → bool

The composed robots are currently composed together. I.e. the disassemble() function has not been called.

Returns:

The disassemble() function has not been called.

Return type:

bool

disassemble()

Disassemble composed robots. This can only be done one time, and it will result in all non-trivial functions in this class returning immediately.

get_fixed_joint_transform()

Get the transform between mount frames in composed robot.

Returns:

translation with shape (3,) and orientation with shape (4,)

Return type:

Tuple[np.array, np.array]

set_fixed_joint_transform(

translation: array,

orientation: array,

)

Set the transform between mount frames in the composed robot.

Parameters:

• translation (np.array) – Local translation relative to mount frame on base robot.

• orientation (np.array) – Local quaternion orientation relative to mount frame on base robot.

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=None,

)

Bases: object

property base_path: str

Prim path of the base body

Returns:

Prim path of the base body

Return type:

str

property attach_path: str

Prim path of the floating (attach) body

Returns:

Prim path of the floating (attach) body

Return type:

str

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

Return type:

UsdPhysics.FixedJoint

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.

Return type:

List[UsdPhysics.Joint]

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

Return type:

Usd.Relationship

is_assembled() → bool

The composed robots are currently composed together. I.e. the disassemble() function has not been called.

Returns:

The disassemble() function has not been called.

Return type:

bool

disassemble()

Disassemble composed robots. This can only be done one time, and it will result in all non-trivial functions in this class returning immediately.

get_fixed_joint_transform() → Tuple[array, array]

Get the transform between mount frames in composed robot.

Returns:

translation with shape (3,) and orientation with shape (4,)

Return type:

Tuple[np.array, np.array]

set_fixed_joint_transform(

translation: array,

orientation: array,

)

Set the transform between mount frames in the composed body.

Parameters:

• translation (np.array) – Local translation relative to mount frame on base body.

• orientation (np.array) – Local quaternion orientation relative to mount frame on base body.