Manipulators [omni.isaac.manipulators]

Single Manipulator

Provides high level functions to set/ get properties and actions of a manipulator with a single end effector and optionally a gripper.

param prim_path: prim path of the Prim to encapsulate or create.
type prim_path: str
param end_effector_prim_name: end effector prim name to be used to track the rigid body that corresponds to the end effector. One of the following args can be specified only: end_effector_prim_name or end_effector_prim_path.
type end_effector_prim_name: str
param end_effector_prim_path: end effector prim path to be used to track the rigid body that corresponds to the end effector. One of the following args can be specified only: end_effector_prim_name or end_effector_prim_path.
type end_effector_prim_path: str
param name: shortname to be used as a key by Scene class. Note: needs to be unique if the object is added to the Scene. Defaults to “single_manipulator”.
type name: str, optional
param position: position in the world frame of the prim. shape is (3, ). Defaults to None, which means left unchanged.
type position: Optional[Sequence[float]], optional
param translation: translation in the local frame of the prim (with respect to its parent prim). shape is (3, ). Defaults to None, which means left unchanged.
type translation: Optional[Sequence[float]], optional
param orientation: quaternion orientation in the world/ local frame of the prim (depends if translation or position is specified). quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.
type orientation: Optional[Sequence[float]], optional
param scale: local scale to be applied to the prim’s dimensions. shape is (3, ). Defaults to None, which means left unchanged.
type scale: Optional[Sequence[float]], optional
param visible: set to false for an invisible prim in the stage while rendering. Defaults to True.
type visible: Optional[bool], optional
param gripper: Gripper to be used with the manipulator. Defaults to None.
type gripper: Gripper, optional

Controllers

Pick and Place Controller

class PickPlaceController(name: str, cspace_controller: omni.isaac.core.controllers.base_controller.BaseController, gripper: omni.isaac.manipulators.grippers.gripper.Gripper, end_effector_initial_height: Optional[float] = None, events_dt: Optional[List[float]] = None)

A simple pick and place state machine for tutorials

Each phase runs for 1 second, which is the internal time of the state machine

Dt of each phase/ event step is defined

Phase 0: Move end_effector above the cube center at the ‘end_effector_initial_height’.
Phase 1: Lower end_effector down to encircle the target cube
Phase 2: Wait for Robot’s inertia to settle.
Phase 3: close grip.
Phase 4: Move end_effector up again, keeping the grip tight (lifting the block).
Phase 5: Smoothly move the end_effector toward the goal xy, keeping the height constant.
Phase 6: Move end_effector vertically toward goal height at the ‘end_effector_initial_height’.
Phase 7: loosen the grip.
Phase 8: Move end_effector vertically up again at the ‘end_effector_initial_height’
Phase 9: Move end_effector towards the old xy position.

Parameters

name (str) – Name id of the controller
cspace_controller (BaseController) – a cartesian space controller that returns an ArticulationAction type
gripper (Gripper) – a gripper controller for open/ close actions.
end_effector_initial_height (Optional[float], optional) – end effector initial picking height to start from (more info in phases above). If not defined, set to 0.3 meters. Defaults to None.
events_dt (Optional[List[float]], optional) – Dt of each phase/ event step. 10 phases dt has to be defined. Defaults to None.

Raises

Exception – events dt need to be list or numpy array
Exception – events dt need have length of 10

forward(picking_position: numpy.ndarray, placing_position: numpy.ndarray, current_joint_positions: numpy.ndarray, end_effector_offset: Optional[numpy.ndarray] = None, end_effector_orientation: Optional[numpy.ndarray] = None) → omni.isaac.core.utils.types.ArticulationAction

Runs the controller one step.

Parameters

picking_position (np.ndarray) – The object’s position to be picked in local frame.
placing_position (np.ndarray) – The object’s position to be placed in local frame.
current_joint_positions (np.ndarray) – Current joint positions of the robot.
end_effector_offset (Optional[np.ndarray], optional) – offset of the end effector target. Defaults to None.
end_effector_orientation (Optional[np.ndarray], optional) – end effector orientation while picking and placing. Defaults to None.

Returns

action to be executed by the ArticulationController

Return type

ArticulationAction

get_current_event() → int

Returns: Current event/ phase of the state machine
Return type: int

is_done() → bool

Returns: True if the state machine reached the last phase. Otherwise False.
Return type: bool

is_paused() → bool

Returns: True if the state machine is paused. Otherwise False.
Return type: bool

pause() → None: Pauses the state machine’s time and phase.

reset(end_effector_initial_height: Optional[float] = None, events_dt: Optional[List[float]] = None) → None

Resets the state machine to start from the first phase/ event

Parameters

end_effector_initial_height (Optional[float], optional) – end effector initial picking height to start from. If not defined, set to 0.3 meters. Defaults to None.
events_dt (Optional[List[float]], optional) – Dt of each phase/ event step. 10 phases dt has to be defined. Defaults to None.

Raises

Exception – events dt need to be list or numpy array
Exception – events dt need have length of 10

resume() → None: Resumes the state machine’s time and phase.

Stacking Controller

class StackingController(name: str, pick_place_controller: omni.isaac.manipulators.controllers.pick_place_controller.PickPlaceController, picking_order_cube_names: List[str], robot_observation_name: str)

[summary]

Parameters

name (str) – [description]
pick_place_controller (PickPlaceController) – [description]
picking_order_cube_names (List[str]) – [description]
robot_observation_name (str) – [description]

forward(observations: dict, end_effector_orientation: Optional[numpy.ndarray] = None, end_effector_offset: Optional[numpy.ndarray] = None) → omni.isaac.core.utils.types.ArticulationAction

A controller should take inputs and returns an ArticulationAction to be then passed to the: ArticulationController.

Parameters: observations (dict) – [description]
Raises: NotImplementedError – [description]
Returns: [description]
Return type: ArticulationAction

is_done() → bool

[summary]

Returns: [description]
Return type: bool

reset(picking_order_cube_names: Optional[List[str]] = None) → None

[summary]

Parameters: picking_order_cube_names (Optional[List[str]], optional) – [description]. Defaults to None.

Grippers

Base Gripper

class Gripper(end_effector_prim_path: str)

Provides high level functions to set/ get properties and actions of a gripper.

Parameters: end_effector_prim_path (str) – prim path of the Prim that corresponds to the gripper root/ end effector.

apply_visual_material(visual_material: omni.isaac.core.materials.visual_material.VisualMaterial, weaker_than_descendants: bool = False) → None

Apply visual material to the held prim and optionally its descendants.

Parameters

visual_material (VisualMaterial) – visual material to be applied to the held prim. Currently supports PreviewSurface, OmniPBR and OmniGlass.
weaker_than_descendants (bool, optional) – True if the material shouldn’t override the descendants materials, otherwise False. Defaults to False.

Example:

>>> from omni.isaac.core.materials import OmniGlass
>>>
>>> # create a dark-red glass visual material
>>> material = OmniGlass(
...     prim_path="/World/material/glass",  # path to the material prim to create
...     ior=1.25,
...     depth=0.001,
...     thin_walled=False,
...     color=np.array([0.5, 0.0, 0.0])
... )
>>> prim.apply_visual_material(material)

abstract close() → None: Applies actions to the articulation that closes the gripper (ex: to hold an object).

disable_rigid_body_physics() → None

Disable the rigid body physics

When disabled, the object will not be moved by external forces such as gravity and collisions

Example:

>>> prim.disable_rigid_body_physics()

enable_rigid_body_physics() → None

Enable the rigid body physics

When enabled, the object will be moved by external forces such as gravity and collisions

Example:

>>> prim.enable_rigid_body_physics()

abstract forward(*args, **kwargs) → omni.isaac.core.utils.types.ArticulationAction

calculates the ArticulationAction for all of the articulation joints that corresponds to a specific action: such as “open” for an example.

Returns

articulation action to be passed to the articulation itself: (includes all joints of the articulation).

Return type

ArticulationAction

get_angular_velocity()

Get the angular velocity of the rigid body

Returns: current angular velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

get_applied_visual_material() → omni.isaac.core.materials.visual_material.VisualMaterial

Return the current applied visual material in case it was applied using apply_visual_material or it’s one of the following materials that was already applied before: PreviewSurface, OmniPBR and OmniGlass.

Returns: the current applied visual material if its type is currently supported.
Return type: VisualMaterial

Example:

>>> # given a visual material applied
>>> prim.get_applied_visual_material()
<omni.isaac.core.materials.omni_glass.OmniGlass object at 0x7f36263106a0>

get_com() → float

Get the center of mass pose of the rigid body

Returns: position of the center of mass of the rigid body. np.ndarray: orientation of the center of mass of the rigid body.
Return type: np.ndarray

get_current_dynamic_state() → omni.isaac.core.utils.types.DynamicState

Get the current rigid body state (position, orientation and linear and angular velocities)

Returns: the dynamic state of the rigid body prim
Return type: DynamicState

Example:

>>> # for the example the rigid body is in free fall
>>> state = prim.get_current_dynamic_state()
>>> state
<omni.isaac.core.utils.types.DynamicState object at 0x7f740b36f670>
>>> state.position
[  0.99999857   2.0000017  -74.2862    ]
>>> state.orientation
[ 1.0000000e+00 -2.3961178e-07 -4.9891562e-09  4.9388258e-09]
>>> state.linear_velocity
[  0.        0.      -38.09554]
>>> state.angular_velocity
[0. 0. 0.]

abstract get_default_state(*args, **kwargs): Gets the default state of the gripper

get_density() → float

Get the density of the rigid body

Returns: density of the rigid body.
Return type: float

Example:

>>> prim.get_density()
0

get_linear_velocity() → numpy.ndarray

Get the linear velocity of the rigid body

Returns: current linear velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

Example:

>>> prim.get_linear_velocity()
[ 1.0812164e-04  6.1415871e-05 -2.1341663e-04]

get_local_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the local frame (the prim’s parent frame)

Returns: first index is the position in the local frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the local frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_local_pose()
>>> position
[0. 0. 0.]
>>> orientation
[0. 0. 0.]

get_local_scale() → numpy.ndarray

Get prim’s scale with respect to the local frame (the parent’s frame)

Returns: scale applied to the prim’s dimensions in the local frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_local_scale()
[1. 1. 1.]

get_mass() → float

Get the mass of the rigid body

Returns: mass of the rigid body in kg.
Return type: float

Example:

>>> prim.get_mass()
0

get_sleep_threshold() → float

Get the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Returns

Mass-normalized kinetic energy threshold below which: an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Return type

float

Example:

>>> prim.get_sleep_threshold()
5e-05

get_visibility() → bool

Returns: true if the prim is visible in stage. false otherwise.
Return type: bool

Example:

>>> # get the visible state of an visible prim on the stage
>>> prim.get_visibility()
True

get_world_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the world’s frame

Returns: first index is the position in the world frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the world frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_world_pose()
>>> position
[1.  0.5 0. ]
>>> orientation
[1. 0. 0. 0.]

get_world_scale() → numpy.ndarray

Get prim’s scale with respect to the world’s frame

Returns: scale applied to the prim’s dimensions in the world frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_world_scale()
[1. 1. 1.]

initialize(physics_sim_view: Optional[omni.physics.tensors.bindings._physicsTensors.SimulationView] = None) → None

Create a physics simulation view if not passed and creates a rigid prim view using physX tensor api.: This needs to be called after each hard reset (i.e stop + play on the timeline) before interacting with any of the functions of this class.

Parameters: physics_sim_view (omni.physics.tensors.SimulationView, optional) – current physics simulation view. Defaults to None.

is_valid() → bool

Check if the prim path has a valid USD Prim at it

Returns: True is the current prim path corresponds to a valid prim in stage. False otherwise.
Return type: bool

Example:

>>> # given an existing and valid prim
>>> prims.is_valid()
True

is_visual_material_applied() → bool

Check if there is a visual material applied

Returns: True if there is a visual material applied. False otherwise.
Return type: bool

Example:

>>> # given a visual material applied
>>> prim.is_visual_material_applied()
True

property name: Optional[str]: Returns: str: name given to the prim when instantiating it. Otherwise None.

property non_root_articulation_link: bool

Used to query if the prim is a non root articulation link

Returns: True if the prim itself is a non root link
Return type: bool

Example:

>>> # for a wrapped articulation (where the root prim has the Physics Articulation Root property applied)
>>> prim.non_root_articulation_link
False

abstract open() → None: Applies actions to the articulation that opens the gripper (ex: to release an object held).

post_reset() → None

Reset the prim to its default state (position and orientation).

Note

For an articulation, in addition to configuring the root prim’s default position and spatial orientation (defined via the set_default_state method), the joint’s positions, velocities, and efforts (defined via the set_joints_default_state method) are imposed

Example:

>>> prim.post_reset()

property prim: pxr.Usd.Prim: Returns: Usd.Prim: USD Prim object that this object holds.

property prim_path: str: Returns: str: prim path in the stage

set_angular_velocity(velocity: numpy.ndarray) → None

Set the angular velocity of the rigid body in stage

Warning

This method will immediately set the articulation state

Parameters: velocity (np.ndarray) – angular velocity to set the rigid prim to. Shape (3,).

set_com(position: numpy.ndarray, orientation: numpy.ndarray) → None

Set the center of mass pose of the rigid body

Parameters

position (np.ndarray) – center of mass position. Shape (3,).
orientation (np.ndarray) – center of mass orientation. Shape (4,).

abstract set_default_state(*args, **kwargs): Sets the default state of the gripper

set_density(density: float) → None

Set the density of the rigid body

Parameters: mass (float) – density of the rigid body.

Example:

>>> prim.set_density(0.9)

set_linear_velocity(velocity: numpy.ndarray)

Set the linear velocity of the rigid body in stage

Warning

This method will immediately set the rigid prim state

Parameters: velocity (np.ndarray) – linear velocity to set the rigid prim to. Shape (3,).

set_local_pose(translation: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Set prim’s pose with respect to the local frame (the prim’s parent frame).

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

translation (Optional[Sequence[float]], optional) – translation in the local frame of the prim (with respect to its parent prim). shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the local frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_local_pose(translation=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

set_local_scale(scale: Optional[Sequence[float]]) → None

Set prim’s scale with respect to the local frame (the prim’s parent frame).

Parameters: scale (Optional[Sequence[float]]) – scale to be applied to the prim’s dimensions. shape is (3, ). Defaults to None, which means left unchanged.

Example:

>>> # scale prim 10 times smaller
>>> prim.set_local_scale(np.array([0.1, 0.1, 0.1]))

set_mass(mass: float) → None

Set the mass of the rigid body

Parameters: mass (float) – mass of the rigid body in kg.

Example:

>>> prim.set_mass(1.0)

set_sleep_threshold(threshold: float) → None

Set the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Parameters: threshold (float) – Mass-normalized kinetic energy threshold below which an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Example:

>>> prim.set_sleep_threshold(1e-5)

set_visibility(visible: bool) → None

Set the visibility of the prim in stage

Parameters: visible (bool) – flag to set the visibility of the usd prim in stage.

Example:

>>> # make prim not visible in the stage
>>> prim.set_visibility(visible=False)

set_world_pose(position: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Ses prim’s pose with respect to the world’s frame

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

position (Optional[Sequence[float]], optional) – position in the world frame of the prim. shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the world frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_world_pose(position=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

Parallel Gripper

class ParallelGripper(end_effector_prim_path: str, joint_prim_names: List[str], joint_opened_positions: numpy.ndarray, joint_closed_positions: numpy.ndarray, action_deltas: Optional[numpy.ndarray] = None)

Provides high level functions to set/ get properties and actions of a parllel gripper (a gripper that has two fingers).

Parameters

end_effector_prim_path (str) – prim path of the Prim that corresponds to the gripper root/ end effector.
joint_prim_names (List[str]) – the left finger joint prim name and the right finger joint prim name respectively.
joint_opened_positions (np.ndarray) – joint positions of the left finger joint and the right finger joint respectively when opened.
joint_closed_positions (np.ndarray) – joint positions of the left finger joint and the right finger joint respectively when closed.
action_deltas (np.ndarray, optional) – deltas to apply for finger joint positions when openning or closing the gripper. Defaults to None.

apply_action(control_actions: omni.isaac.core.utils.types.ArticulationAction) → None

Applies actions to all the joints of an articulation that corresponds to the ArticulationAction of the finger joints only.

Parameters: control_actions (ArticulationAction) – ArticulationAction for the left finger joint and the right finger joint respectively.

apply_visual_material(visual_material: omni.isaac.core.materials.visual_material.VisualMaterial, weaker_than_descendants: bool = False) → None

Apply visual material to the held prim and optionally its descendants.

Parameters

visual_material (VisualMaterial) – visual material to be applied to the held prim. Currently supports PreviewSurface, OmniPBR and OmniGlass.
weaker_than_descendants (bool, optional) – True if the material shouldn’t override the descendants materials, otherwise False. Defaults to False.

Example:

>>> from omni.isaac.core.materials import OmniGlass
>>>
>>> # create a dark-red glass visual material
>>> material = OmniGlass(
...     prim_path="/World/material/glass",  # path to the material prim to create
...     ior=1.25,
...     depth=0.001,
...     thin_walled=False,
...     color=np.array([0.5, 0.0, 0.0])
... )
>>> prim.apply_visual_material(material)

close() → None: Applies actions to the articulation that closes the gripper (ex: to hold an object).

disable_rigid_body_physics() → None

Disable the rigid body physics

When disabled, the object will not be moved by external forces such as gravity and collisions

Example:

>>> prim.disable_rigid_body_physics()

enable_rigid_body_physics() → None

Enable the rigid body physics

When enabled, the object will be moved by external forces such as gravity and collisions

Example:

>>> prim.enable_rigid_body_physics()

forward(action: str) → omni.isaac.core.utils.types.ArticulationAction

calculates the ArticulationAction for all of the articulation joints that corresponds to “open”: or “close” actions.

Parameters

action (str) – “open” or “close” as an abstract action.

Raises

Exception – _description_

Returns

articulation action to be passed to the articulation itself: (includes all joints of the articulation).

Return type

ArticulationAction

get_action_deltas() → numpy.ndarray

Returns

deltas that will be applied for finger joint positions when openning or closing the gripper.: [left, right]. Defaults to None.

Return type

np.ndarray

get_angular_velocity()

Get the angular velocity of the rigid body

Returns: current angular velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

get_applied_visual_material() → omni.isaac.core.materials.visual_material.VisualMaterial

Return the current applied visual material in case it was applied using apply_visual_material or it’s one of the following materials that was already applied before: PreviewSurface, OmniPBR and OmniGlass.

Returns: the current applied visual material if its type is currently supported.
Return type: VisualMaterial

Example:

>>> # given a visual material applied
>>> prim.get_applied_visual_material()
<omni.isaac.core.materials.omni_glass.OmniGlass object at 0x7f36263106a0>

get_com() → float

Get the center of mass pose of the rigid body

Returns: position of the center of mass of the rigid body. np.ndarray: orientation of the center of mass of the rigid body.
Return type: np.ndarray

get_current_dynamic_state() → omni.isaac.core.utils.types.DynamicState

Get the current rigid body state (position, orientation and linear and angular velocities)

Returns: the dynamic state of the rigid body prim
Return type: DynamicState

Example:

>>> # for the example the rigid body is in free fall
>>> state = prim.get_current_dynamic_state()
>>> state
<omni.isaac.core.utils.types.DynamicState object at 0x7f740b36f670>
>>> state.position
[  0.99999857   2.0000017  -74.2862    ]
>>> state.orientation
[ 1.0000000e+00 -2.3961178e-07 -4.9891562e-09  4.9388258e-09]
>>> state.linear_velocity
[  0.        0.      -38.09554]
>>> state.angular_velocity
[0. 0. 0.]

get_default_state() → numpy.ndarray

Gets the default state of the gripper

Returns: joint positions of the left finger joint and the right finger joint respectively.
Return type: np.ndarray

get_density() → float

Get the density of the rigid body

Returns: density of the rigid body.
Return type: float

Example:

>>> prim.get_density()
0

get_joint_positions() → numpy.ndarray

Returns: joint positions of the left finger joint and the right finger joint respectively.
Return type: np.ndarray

get_linear_velocity() → numpy.ndarray

Get the linear velocity of the rigid body

Returns: current linear velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

Example:

>>> prim.get_linear_velocity()
[ 1.0812164e-04  6.1415871e-05 -2.1341663e-04]

get_local_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the local frame (the prim’s parent frame)

Returns: first index is the position in the local frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the local frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_local_pose()
>>> position
[0. 0. 0.]
>>> orientation
[0. 0. 0.]

get_local_scale() → numpy.ndarray

Get prim’s scale with respect to the local frame (the parent’s frame)

Returns: scale applied to the prim’s dimensions in the local frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_local_scale()
[1. 1. 1.]

get_mass() → float

Get the mass of the rigid body

Returns: mass of the rigid body in kg.
Return type: float

Example:

>>> prim.get_mass()
0

get_sleep_threshold() → float

Get the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Returns

Mass-normalized kinetic energy threshold below which: an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Return type

float

Example:

>>> prim.get_sleep_threshold()
5e-05

get_visibility() → bool

Returns: true if the prim is visible in stage. false otherwise.
Return type: bool

Example:

>>> # get the visible state of an visible prim on the stage
>>> prim.get_visibility()
True

get_world_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the world’s frame

Returns: first index is the position in the world frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the world frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_world_pose()
>>> position
[1.  0.5 0. ]
>>> orientation
[1. 0. 0. 0.]

get_world_scale() → numpy.ndarray

Get prim’s scale with respect to the world’s frame

Returns: scale applied to the prim’s dimensions in the world frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_world_scale()
[1. 1. 1.]

initialize(articulation_apply_action_func: Callable, get_joint_positions_func: Callable, set_joint_positions_func: Callable, dof_names: List, physics_sim_view: Optional[omni.physics.tensors.bindings._physicsTensors.SimulationView] = None) → None

Create a physics simulation view if not passed and creates a rigid prim view using physX tensor api.: This needs to be called after each hard reset (i.e stop + play on the timeline) before interacting with any of the functions of this class.

Parameters

articulation_apply_action_func (Callable) – apply_action function from the Articulation class.
get_joint_positions_func (Callable) – get_joint_positions function from the Articulation class.
set_joint_positions_func (Callable) – set_joint_positions function from the Articulation class.
dof_names (List) – dof names from the Articulation class.
physics_sim_view (omni.physics.tensors.SimulationView, optional) – current physics simulation view. Defaults to None

Raises

Exception – _description_

is_valid() → bool

Check if the prim path has a valid USD Prim at it

Returns: True is the current prim path corresponds to a valid prim in stage. False otherwise.
Return type: bool

Example:

>>> # given an existing and valid prim
>>> prims.is_valid()
True

is_visual_material_applied() → bool

Check if there is a visual material applied

Returns: True if there is a visual material applied. False otherwise.
Return type: bool

Example:

>>> # given a visual material applied
>>> prim.is_visual_material_applied()
True

property joint_closed_positions: numpy.ndarray: Returns: np.ndarray: joint positions of the left finger joint and the right finger joint respectively when closed.

property joint_dof_indicies: numpy.ndarray: Returns: np.ndarray: joint dof indices in the articulation of the left finger joint and the right finger joint respectively.

property joint_opened_positions: numpy.ndarray: Returns: np.ndarray: joint positions of the left finger joint and the right finger joint respectively when opened.

property joint_prim_names: List[str]: Returns: List[str]: the left finger joint prim name and the right finger joint prim name respectively.

property name: Optional[str]: Returns: str: name given to the prim when instantiating it. Otherwise None.

property non_root_articulation_link: bool

Used to query if the prim is a non root articulation link

Returns: True if the prim itself is a non root link
Return type: bool

Example:

>>> # for a wrapped articulation (where the root prim has the Physics Articulation Root property applied)
>>> prim.non_root_articulation_link
False

open() → None: Applies actions to the articulation that opens the gripper (ex: to release an object held).

post_reset()

Reset the prim to its default state (position and orientation).

Note

For an articulation, in addition to configuring the root prim’s default position and spatial orientation (defined via the set_default_state method), the joint’s positions, velocities, and efforts (defined via the set_joints_default_state method) are imposed

Example:

>>> prim.post_reset()

property prim: pxr.Usd.Prim: Returns: Usd.Prim: USD Prim object that this object holds.

property prim_path: str: Returns: str: prim path in the stage

set_action_deltas(value: numpy.ndarray) → None

Parameters: value (np.ndarray) – deltas to apply for finger joint positions when openning or closing the gripper. [left, right]. Defaults to None.

set_angular_velocity(velocity: numpy.ndarray) → None

Set the angular velocity of the rigid body in stage

Warning

This method will immediately set the articulation state

Parameters: velocity (np.ndarray) – angular velocity to set the rigid prim to. Shape (3,).

set_com(position: numpy.ndarray, orientation: numpy.ndarray) → None

Set the center of mass pose of the rigid body

Parameters

position (np.ndarray) – center of mass position. Shape (3,).
orientation (np.ndarray) – center of mass orientation. Shape (4,).

set_default_state(joint_positions: numpy.ndarray) → None

Sets the default state of the gripper

Parameters: joint_positions (np.ndarray) – joint positions of the left finger joint and the right finger joint respectively.

set_density(density: float) → None

Set the density of the rigid body

Parameters: mass (float) – density of the rigid body.

Example:

>>> prim.set_density(0.9)

set_joint_positions(positions: numpy.ndarray) → None

Parameters: positions (np.ndarray) – joint positions of the left finger joint and the right finger joint respectively.

set_linear_velocity(velocity: numpy.ndarray)

Set the linear velocity of the rigid body in stage

Warning

This method will immediately set the rigid prim state

Parameters: velocity (np.ndarray) – linear velocity to set the rigid prim to. Shape (3,).

set_local_pose(translation: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Set prim’s pose with respect to the local frame (the prim’s parent frame).

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

translation (Optional[Sequence[float]], optional) – translation in the local frame of the prim (with respect to its parent prim). shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the local frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_local_pose(translation=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

set_local_scale(scale: Optional[Sequence[float]]) → None

Set prim’s scale with respect to the local frame (the prim’s parent frame).

Parameters: scale (Optional[Sequence[float]]) – scale to be applied to the prim’s dimensions. shape is (3, ). Defaults to None, which means left unchanged.

Example:

>>> # scale prim 10 times smaller
>>> prim.set_local_scale(np.array([0.1, 0.1, 0.1]))

set_mass(mass: float) → None

Set the mass of the rigid body

Parameters: mass (float) – mass of the rigid body in kg.

Example:

>>> prim.set_mass(1.0)

set_sleep_threshold(threshold: float) → None

Set the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Parameters: threshold (float) – Mass-normalized kinetic energy threshold below which an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Example:

>>> prim.set_sleep_threshold(1e-5)

set_visibility(visible: bool) → None

Set the visibility of the prim in stage

Parameters: visible (bool) – flag to set the visibility of the usd prim in stage.

Example:

>>> # make prim not visible in the stage
>>> prim.set_visibility(visible=False)

set_world_pose(position: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Ses prim’s pose with respect to the world’s frame

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

position (Optional[Sequence[float]], optional) – position in the world frame of the prim. shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the world frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_world_pose(position=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

Surface Gripper

class SurfaceGripper(end_effector_prim_path: str, translate: float = 0, direction: str = 'x', grip_threshold: float = 0.01, force_limit: float = 1000000.0, torque_limit: float = 10000.0, bend_angle: float = 0.1308996938995747, kp: float = 100.0, kd: float = 100.0, disable_gravity: bool = True)

Provides high level functions to set/ get properties and actions of a surface gripper (a suction cup for example).

Parameters

end_effector_prim_path (str) – prim path of the Prim that corresponds to the gripper root/ end effector.
translate (float, optional) – _description_. Defaults to 0.
direction (str, optional) – _description_. Defaults to “x”.
grip_threshold (float, optional) – _description_. Defaults to 0.01.
force_limit (float, optional) – _description_. Defaults to 1.0e6.
torque_limit (float, optional) – _description_. Defaults to 1.0e4.
bend_angle (float, optional) – _description_. Defaults to np.pi/24.
kp (float, optional) – _description_. Defaults to 1.0e2.
kd (float, optional) – _description_. Defaults to 1.0e2.
disable_gravity (bool, optional) – _description_. Defaults to True.

apply_visual_material(visual_material: omni.isaac.core.materials.visual_material.VisualMaterial, weaker_than_descendants: bool = False) → None

Apply visual material to the held prim and optionally its descendants.

Parameters

visual_material (VisualMaterial) – visual material to be applied to the held prim. Currently supports PreviewSurface, OmniPBR and OmniGlass.
weaker_than_descendants (bool, optional) – True if the material shouldn’t override the descendants materials, otherwise False. Defaults to False.

Example:

>>> from omni.isaac.core.materials import OmniGlass
>>>
>>> # create a dark-red glass visual material
>>> material = OmniGlass(
...     prim_path="/World/material/glass",  # path to the material prim to create
...     ior=1.25,
...     depth=0.001,
...     thin_walled=False,
...     color=np.array([0.5, 0.0, 0.0])
... )
>>> prim.apply_visual_material(material)

close() → None: Applies actions to the articulation that closes the gripper (ex: to hold an object).

disable_rigid_body_physics() → None

Disable the rigid body physics

When disabled, the object will not be moved by external forces such as gravity and collisions

Example:

>>> prim.disable_rigid_body_physics()

enable_rigid_body_physics() → None

Enable the rigid body physics

When enabled, the object will be moved by external forces such as gravity and collisions

Example:

>>> prim.enable_rigid_body_physics()

forward(action: str) → omni.isaac.core.utils.types.ArticulationAction

calculates the ArticulationAction for all of the articulation joints that corresponds to “open”: or “close” actions.

Parameters

action (str) – “open” or “close” as an abstract action.

Raises

Exception – _description_

Returns

articulation action to be passed to the articulation itself: (includes all joints of the articulation).

Return type

ArticulationAction

get_angular_velocity()

Get the angular velocity of the rigid body

Returns: current angular velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

get_applied_visual_material() → omni.isaac.core.materials.visual_material.VisualMaterial

Return the current applied visual material in case it was applied using apply_visual_material or it’s one of the following materials that was already applied before: PreviewSurface, OmniPBR and OmniGlass.

Returns: the current applied visual material if its type is currently supported.
Return type: VisualMaterial

Example:

>>> # given a visual material applied
>>> prim.get_applied_visual_material()
<omni.isaac.core.materials.omni_glass.OmniGlass object at 0x7f36263106a0>

get_com() → float

Get the center of mass pose of the rigid body

Returns: position of the center of mass of the rigid body. np.ndarray: orientation of the center of mass of the rigid body.
Return type: np.ndarray

get_current_dynamic_state() → omni.isaac.core.utils.types.DynamicState

Get the current rigid body state (position, orientation and linear and angular velocities)

Returns: the dynamic state of the rigid body prim
Return type: DynamicState

Example:

>>> # for the example the rigid body is in free fall
>>> state = prim.get_current_dynamic_state()
>>> state
<omni.isaac.core.utils.types.DynamicState object at 0x7f740b36f670>
>>> state.position
[  0.99999857   2.0000017  -74.2862    ]
>>> state.orientation
[ 1.0000000e+00 -2.3961178e-07 -4.9891562e-09  4.9388258e-09]
>>> state.linear_velocity
[  0.        0.      -38.09554]
>>> state.angular_velocity
[0. 0. 0.]

get_default_state() → dict

Gets the default state of the gripper

Returns: key is “opened” and value would be true if the surface gripper should start in an opened state. False otherwise.
Return type: dict

get_density() → float

Get the density of the rigid body

Returns: density of the rigid body.
Return type: float

Example:

>>> prim.get_density()
0

get_linear_velocity() → numpy.ndarray

Get the linear velocity of the rigid body

Returns: current linear velocity of the the rigid prim. Shape (3,).
Return type: np.ndarray

Example:

>>> prim.get_linear_velocity()
[ 1.0812164e-04  6.1415871e-05 -2.1341663e-04]

get_local_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the local frame (the prim’s parent frame)

Returns: first index is the position in the local frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the local frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_local_pose()
>>> position
[0. 0. 0.]
>>> orientation
[0. 0. 0.]

get_local_scale() → numpy.ndarray

Get prim’s scale with respect to the local frame (the parent’s frame)

Returns: scale applied to the prim’s dimensions in the local frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_local_scale()
[1. 1. 1.]

get_mass() → float

Get the mass of the rigid body

Returns: mass of the rigid body in kg.
Return type: float

Example:

>>> prim.get_mass()
0

get_sleep_threshold() → float

Get the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Returns

Mass-normalized kinetic energy threshold below which: an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Return type

float

Example:

>>> prim.get_sleep_threshold()
5e-05

get_visibility() → bool

Returns: true if the prim is visible in stage. false otherwise.
Return type: bool

Example:

>>> # get the visible state of an visible prim on the stage
>>> prim.get_visibility()
True

get_world_pose() → Tuple[numpy.ndarray, numpy.ndarray]

Get prim’s pose with respect to the world’s frame

Returns: first index is the position in the world frame (with shape (3, )). Second index is quaternion orientation (with shape (4, )) in the world frame
Return type: Tuple[np.ndarray, np.ndarray]

Example:

>>> # if the prim is in position (1.0, 0.5, 0.0) with respect to the world frame
>>> position, orientation = prim.get_world_pose()
>>> position
[1.  0.5 0. ]
>>> orientation
[1. 0. 0. 0.]

get_world_scale() → numpy.ndarray

Get prim’s scale with respect to the world’s frame

Returns: scale applied to the prim’s dimensions in the world frame. shape is (3, ).
Return type: np.ndarray

Example:

>>> prim.get_world_scale()
[1. 1. 1.]

initialize(physics_sim_view: Optional[omni.physics.tensors.bindings._physicsTensors.SimulationView] = None, articulation_num_dofs: Optional[int] = None) → None

Create a physics simulation view if not passed and creates a rigid prim view using physX tensor api.: This needs to be called after each hard reset (i.e stop + play on the timeline) before interacting with any of the functions of this class.

Parameters

physics_sim_view (omni.physics.tensors.SimulationView, optional) – current physics simulation view. Defaults to None
articulation_num_dofs (int, optional) – num of dofs of the Articulation. Defaults to None.

is_closed() → bool

is_valid() → bool

Check if the prim path has a valid USD Prim at it

Returns: True is the current prim path corresponds to a valid prim in stage. False otherwise.
Return type: bool

Example:

>>> # given an existing and valid prim
>>> prims.is_valid()
True

is_visual_material_applied() → bool

Check if there is a visual material applied

Returns: True if there is a visual material applied. False otherwise.
Return type: bool

Example:

>>> # given a visual material applied
>>> prim.is_visual_material_applied()
True

property name: Optional[str]: Returns: str: name given to the prim when instantiating it. Otherwise None.

property non_root_articulation_link: bool

Used to query if the prim is a non root articulation link

Returns: True if the prim itself is a non root link
Return type: bool

Example:

>>> # for a wrapped articulation (where the root prim has the Physics Articulation Root property applied)
>>> prim.non_root_articulation_link
False

open() → None: Applies actions to the articulation that opens the gripper (ex: to release an object held).

post_reset()

Reset the prim to its default state (position and orientation).

Note

For an articulation, in addition to configuring the root prim’s default position and spatial orientation (defined via the set_default_state method), the joint’s positions, velocities, and efforts (defined via the set_joints_default_state method) are imposed

Example:

>>> prim.post_reset()

property prim: pxr.Usd.Prim: Returns: Usd.Prim: USD Prim object that this object holds.

property prim_path: str: Returns: str: prim path in the stage

set_angular_velocity(velocity: numpy.ndarray) → None

Set the angular velocity of the rigid body in stage

Warning

This method will immediately set the articulation state

Parameters: velocity (np.ndarray) – angular velocity to set the rigid prim to. Shape (3,).

set_com(position: numpy.ndarray, orientation: numpy.ndarray) → None

Set the center of mass pose of the rigid body

Parameters

position (np.ndarray) – center of mass position. Shape (3,).
orientation (np.ndarray) – center of mass orientation. Shape (4,).

set_default_state(opened: bool)

Sets the default state of the gripper

Parameters: opened (bool) – True if the surface gripper should start in an opened state. False otherwise.

set_density(density: float) → None

Set the density of the rigid body

Parameters: mass (float) – density of the rigid body.

Example:

>>> prim.set_density(0.9)

set_direction(value: float) → None

set_force_limit(value: float) → None

set_linear_velocity(velocity: numpy.ndarray)

Set the linear velocity of the rigid body in stage

Warning

This method will immediately set the rigid prim state

Parameters: velocity (np.ndarray) – linear velocity to set the rigid prim to. Shape (3,).

set_local_pose(translation: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Set prim’s pose with respect to the local frame (the prim’s parent frame).

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

translation (Optional[Sequence[float]], optional) – translation in the local frame of the prim (with respect to its parent prim). shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the local frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_local_pose(translation=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

set_local_scale(scale: Optional[Sequence[float]]) → None

Set prim’s scale with respect to the local frame (the prim’s parent frame).

Parameters: scale (Optional[Sequence[float]]) – scale to be applied to the prim’s dimensions. shape is (3, ). Defaults to None, which means left unchanged.

Example:

>>> # scale prim 10 times smaller
>>> prim.set_local_scale(np.array([0.1, 0.1, 0.1]))

set_mass(mass: float) → None

Set the mass of the rigid body

Parameters: mass (float) – mass of the rigid body in kg.

Example:

>>> prim.set_mass(1.0)

set_sleep_threshold(threshold: float) → None

Set the threshold for the rigid body to enter a sleep state

Search for Rigid Body Dynamics > Sleeping in PhysX docs for more details

Parameters: threshold (float) – Mass-normalized kinetic energy threshold below which an actor may go to sleep. Range: [0, inf) Defaults: 0.00005 * tolerancesSpeed* tolerancesSpeed Units: distance^2 / second^2.

Example:

>>> prim.set_sleep_threshold(1e-5)

set_torque_limit(value: float) → None

set_translate(value: float) → None

set_visibility(visible: bool) → None

Set the visibility of the prim in stage

Parameters: visible (bool) – flag to set the visibility of the usd prim in stage.

Example:

>>> # make prim not visible in the stage
>>> prim.set_visibility(visible=False)

set_world_pose(position: Optional[Sequence[float]] = None, orientation: Optional[Sequence[float]] = None) → None

Ses prim’s pose with respect to the world’s frame

Warning

This method will change (teleport) the prim pose immediately to the indicated value

Parameters

position (Optional[Sequence[float]], optional) – position in the world frame of the prim. shape is (3, ). Defaults to None, which means left unchanged.
orientation (Optional[Sequence[float]], optional) – quaternion orientation in the world frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ). Defaults to None, which means left unchanged.

Hint

This method belongs to the methods used to set the prim state

Example:

>>> prim.set_world_pose(position=np.array([1.0, 0.5, 0.0]), orientation=np.array([1., 0., 0., 0.]))

update() → None