Wheeled Robots [omni.isaac.wheeled_robots]

Controllers (Python API)

class DifferentialController(name: str, wheel_radius: float, wheel_base: float, max_linear_speed: float = 1e+20, max_angular_speed: float = 1e+20, max_wheel_speed: float = 1e+20)

Controller uses unicycle model for a differential drive

Parameters

  • name (str) – [description]

  • wheel_radius (float) – Radius of left and right wheels in cms

  • wheel_base (float) – Distance between left and right wheels in cms

forward(command: numpy.ndarray) → omni.isaac.core.utils.types.ArticulationAction

Calculating the wheels speeds given the desired speed for the vehicle.

Parameters

command (np.ndarray) – desired vehicle [forward, rotation] speed

Returns

[description]

Return type

ArticulationAction

reset() → None

[summary]

class HolonomicController(name: str, wheel_radius: Optional[numpy.ndarray] = None, wheel_positions: Optional[numpy.ndarray] = None, wheel_orientations: Optional[numpy.ndarray] = None, mecanum_angles: Optional[numpy.ndarray] = None, wheel_axis: float = array([1, 0, 0]), up_axis: float = array([0, 0, 1]), max_linear_speed: float = 1e+20, max_angular_speed: float = 1e+20, max_wheel_speed: float = 1e+20, linear_gain: float = 1.0, angular_gain: float = 1.0)

[summary] Generic Holonomic drive controller. Model must have drive joints to mecanum wheels defined in the USD with the rollers angle and radius.

Parameters

  • name (str) – [description]

  • wheel_radius (np.ndarray) – radius of the wheels, array of 1 can be used if all wheels are the same size

  • wheel_positions (np.ndarray) – position of the wheels relative to center of mass of the vehicle. number of wheels x [x,y,z]

  • wheel_orientations (np.ndarray) – orientation of the wheels in quaternions relative to center of mass frame of the vehicle. number of wheels x [quaternions]

  • mecanum_angles (np.ndarray) – mecanum wheel angles. Array of 1 can be used if all wheels have the same angle.

  • wheel_axis (np.ndarray) – the spinning axis of the wheels. Defaults to [1,0,0]

  • up_axis (np.ndarray) – Defaults to z- axis

build_base()
forward(command: numpy.ndarray) → omni.isaac.core.utils.types.ArticulationAction

Calculating the wheels speed given the desired vehicle speed.

Parameters

command (np.ndarray) – [forward_velocity, lateral_velocity, yaw_velocity].

Returns

[description]

Return type

ArticulationAction

reset() → None

[summary]

Utilities

class HolonomicRobotUsdSetup(robot_prim_path: str, com_prim_path: str)

[summary] Generic Holonomic Robot Setup. Extract from USD or compile from user input the necessary information for holonomic controller. :param name: [description] :type name: str :param prim_path: path of the robot articulation :type prim_path: str :param com_prim_path: path of the xform representing the center of mass of the vehicle :type com_prim_path: str

from_usd(robot_prim_path, com_prim_path)

if the USD contains all the necessary information, automatically extract them and compile

get_articulation_controller_params()
get_holonomic_controller_params()
property mecanum_angles
property up_axis
property wheel_axis
property wheel_dof_names
property wheel_orientations
property wheel_positions
property wheel_radius
class WheeledRobot(prim_path: str, robot_path: Optional[str] = None, wheel_dof_names: Optional[str] = None, wheel_dof_indices: Optional[int] = None, name: str = 'wheeled_robot', usd_path: Optional[str] = None, create_robot: Optional[bool] = False, position: Optional[numpy.ndarray] = None, orientation: Optional[numpy.ndarray] = None)

[summary]

Parameters

  • prim_path (str) – [description]

  • robot_path (str) – relative path from prim path to the robot.

  • name (str) – [description]

  • wheel_dof_names ([str, str]) – name of the wheels, [left,right].

  • wheel_dof_indices – ([int, int]): indices of the wheels, [left, right]

  • usd_path (str, optional) – [description]

  • create_robot (bool) – create robot at prim_path if no robot exist at said path. Defaults to False

  • position (Optional[np.ndarray], optional) – [description]. Defaults to None.

  • orientation (Optional[np.ndarray], optional) – [description]. Defaults to None.

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

[summary]

Parameters

  • control_actions (ArticulationAction) – actions to be applied for next physics step.

  • indices (Optional[Union[list, np.ndarray]], optional) – degree of freedom indices to apply actions to. Defaults to all degrees of freedom.

Raises

Exception – [description]

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

Used to 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.

apply_wheel_actions(actions: omni.isaac.core.utils.types.ArticulationAction) → None

applying action to the wheels to move the robot

Parameters

actions (ArticulationAction) – [description]

property articulation_handle: int

[summary]

Returns

[description]

Return type

int

disable_gravity() → None

Keep gravity from affecting the robot

property dof_names: List[str]

List of prim names for each DOF.

Returns

prim names

Return type

list(string)

property dof_properties: numpy.ndarray

[summary]

Returns

[description]

Return type

np.ndarray

enable_gravity() → None

Gravity will affect the robot

get_angular_velocity() → numpy.ndarray

[summary]

Returns

[description]

Return type

np.ndarray

get_applied_action() → omni.isaac.core.utils.types.ArticulationAction

[summary]

Raises

Exception – [description]

Returns

[description]

Return type

ArticulationAction

get_applied_joint_efforts(joint_indices: Optional[Union[List, numpy.ndarray]] = None) → numpy.ndarray

Gets the efforts applied to the joints

Parameters

joint_indices (Optional[Union[List, np.ndarray]], optional) – _description_. Defaults to None.

Raises

Exception – _description_

Returns

_description_

Return type

np.ndarray

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

get_articulation_body_count() → int

[summary]

Returns

[description]

Return type

int

get_articulation_controller() → omni.isaac.core.controllers.articulation_controller.ArticulationController
Returns

PD Controller of all degrees of freedom of an articulation, can apply position targets, velocity targets and efforts.

Return type

ArticulationController

get_articulation_controller_properties()
get_default_state() → omni.isaac.core.utils.types.XFormPrimState
Returns

returns the default state of the prim (position and orientation) that is used after each reset.

Return type

XFormPrimState

get_dof_index(dof_name: str) → int

[summary]

Parameters

dof_name (str) – [description]

Returns

[description]

Return type

int

get_enabled_self_collisions() → bool

[summary]

Returns

[description]

Return type

bool

get_joint_positions(joint_indices: Optional[Union[List, numpy.ndarray]] = None) → numpy.ndarray

_summary_

Parameters

joint_indices (Optional[Union[List, np.ndarray]], optional) – _description_. Defaults to None.

Returns

_description_

Return type

np.ndarray

get_joint_velocities(joint_indices: Optional[Union[List, numpy.ndarray]] = None) → numpy.ndarray

_summary_

Parameters

joint_indices (Optional[Union[List, np.ndarray]], optional) – _description_. Defaults to None.

Returns

_description_

Return type

np.ndarray

get_joints_default_state() → omni.isaac.core.utils.types.JointsState

Accessor for the default joints state.

Returns

The defaults that the robot is reset to when post_reset() is called (often automatically called during world.reset()).

Return type

JointsState

get_joints_state() → omni.isaac.core.utils.types.JointsState

[summary]

Returns

[description]

Return type

JointsState

get_linear_velocity() → numpy.ndarray

[summary]

Returns

[description]

Return type

np.ndarray

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

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

Returns

first index is position in the local frame of the prim. shape is (3, ).

second index is quaternion orientation in the local frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ).

Return type

Tuple[np.ndarray, np.ndarray]

get_local_scale() → numpy.ndarray

Gets 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

get_measured_joint_efforts(joint_indices: Optional[Union[List, numpy.ndarray]] = None) → numpy.ndarray

Returns the dof efforts computed/measured by the physics solver

Parameters

joint_indices (Optional[Union[List, np.ndarray]], optional) – _description_. Defaults to None.

Raises

Exception – _description_

Returns

_description_

Return type

np.ndarray

get_measured_joint_forces(joint_indices: Optional[Union[List, numpy.ndarray]] = None) → numpy.ndarray

Gets the measured joint forces

Parameters

joint_indices (Optional[Union[List, np.ndarray]], optional) – _description_. Defaults to None.

Raises

Exception – _description_

Returns

_description_

Return type

np.ndarray

get_sleep_threshold() → float

[summary]

Returns

[description]

Return type

float

get_solver_position_iteration_count() → int

[summary]

Returns

[description]

Return type

int

get_solver_velocity_iteration_count() → int

[summary]

Returns

[description]

Return type

int

get_stabilization_threshold() → float

[summary]

Returns

[description]

Return type

float

get_visibility() → bool
Returns

true if the prim is visible in stage. false otherwise.

Return type

bool

get_wheel_positions()

[summary]

Returns

[description]

Return type

Tuple[float, float]

get_wheel_velocities()

[summary]

Returns

[description]

Return type

Tuple[np.ndarray, np.ndarray]

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

Gets prim’s pose with respect to the world’s frame.

Returns

first index is position in the world frame of the prim. shape is (3, ).

second index is quaternion orientation in the world frame of the prim. quaternion is scalar-first (w, x, y, z). shape is (4, ).

Return type

Tuple[np.ndarray, np.ndarray]

get_world_scale() → numpy.ndarray

Gets 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

property handles_initialized: bool

[summary]

Returns

[description]

Return type

bool

initialize(physics_sim_view=None) → None

[summary]

is_valid() → bool
Returns

True is the current prim path corresponds to a valid prim in stage. False otherwise.

Return type

bool

is_visual_material_applied() → bool
Returns

True if there is a visual material applied. False otherwise.

Return type

bool

property name: Optional[str]

Returns: str: name given to the prim when instantiating it. Otherwise None.

_summary_

Returns

_description_

Return type

bool

property num_dof: int

[summary]

Returns

[description]

Return type

int

post_reset() → None

[summary]

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

[summary]

Parameters

velocity (np.ndarray) – [description]

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

Sets the default state of the prim (position and orientation), that will be used after each reset.

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.

set_enabled_self_collisions(flag: bool) → None

[summary]

Parameters

flag (bool) – [description]

set_joint_efforts(efforts: numpy.ndarray, joint_indices: Optional[Union[List, numpy.ndarray]] = None) → None

[summary]

Parameters

  • efforts (np.ndarray) – [description]

  • joint_indices (Optional[Union[list, np.ndarray]], optional) – [description]. Defaults to None.

Raises

Exception – [description]

set_joint_positions(positions: numpy.ndarray, joint_indices: Optional[Union[List, numpy.ndarray]] = None) → None

[summary]

Parameters

  • positions (np.ndarray) – [description]

  • indices (Optional[Union[list, np.ndarray]], optional) – [description]. Defaults to None.

Raises

Exception – [description]

set_joint_velocities(velocities: numpy.ndarray, joint_indices: Optional[Union[List, numpy.ndarray]] = None) → None

[summary]

Parameters

  • velocities (np.ndarray) – [description]

  • indices (Optional[Union[list, np.ndarray]], optional) – [description]. Defaults to None.

Raises

Exception – [description]

set_joints_default_state(positions: Optional[numpy.ndarray] = None, velocities: Optional[numpy.ndarray] = None, efforts: Optional[numpy.ndarray] = None) → None

[summary]

Parameters

  • positions (Optional[np.ndarray], optional) – [description]. Defaults to None.

  • velocities (Optional[np.ndarray], optional) – [description]. Defaults to None.

  • efforts (Optional[np.ndarray], optional) – [description]. Defaults to None.

set_linear_velocity(velocity: numpy.ndarray)

Sets the linear velocity of the prim in stage.

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

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

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.

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

Sets 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.

set_sleep_threshold(threshold: float) → None

[summary]

Parameters

threshold (float) – [description]

set_solver_position_iteration_count(count: int) → None

[summary]

Parameters

count (int) – [description]

set_solver_velocity_iteration_count(count: int)

[summary]

Parameters

count (int) – [description]

set_stabilization_threshold(threshold: float) → None

[summary]

Parameters

threshold (float) – [description]

set_visibility(visible: bool) → None

Sets the visibility of the prim in stage.

Parameters

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

set_wheel_positions(positions) → None

[summary]

Parameters

positions (Tuple[float, float]) – [description]

set_wheel_velocities(velocities) → None

[summary]

Parameters

velocities (Tuple[float, float]) – [description]

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

Sets prim’s pose with respect to the world’s frame.

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.

property wheel_dof_indices

[summary]

Returns

[description]

Return type

int

Omnigraph Nodes

DifferentialController

Differential Controller

Use the wheel radius and the distance between the wheels to calculate the desired wheels speed when given a desired vehicle speed.

Inputs

  • execIn (execution): The input execution.

  • wheelRadius (double): radius of the wheels.

  • wheelDistance (double): distance between the two wheels.

  • maxLinearSpeed (double): max linear speed allowed for vehicle.

  • maxAngularSpeed (double): max angular speed allowed for vehicle.

  • maxWheelSpeed (double): max wheel speed allowed.

  • linearVelocity (double): desired linear velocity.

  • angularVelocity (double): desired rotation velocity.

Outputs

  • positionCommand (double[]): position commands.

  • velocityCommand (double[]): velocity commands.

  • effortCommand (double[]): effort commands.

QuinticPathPlanner

Quintic Path Planner For Wheeled robots

Use odometry from a robot and a target position/prim to calculate a route from the robot’s starting position to the target position.

Inputs

  • execIn (execution): The input execution.

  • currentPosition (vectord[3]): Current position of the robot (recommended to use Get Prim Local to World Transform node).

  • currentOrientation (quatd[4]): Current rotation of the robot as a quaternion (recommended to use Get Prim Local to World Transform node).

  • targetPrim (target, optional): USD prim reference to the target position/orientation prim.

  • targetPosition (vectord[3]): Target position (used if no targetPrim provided).

  • targetOrientation (quatd[4]): Target orientation (used if no targetPrim provided).

  • initialVelocity (double): Initial velocity. Default to 0.5.

  • initialAccel (double): Initial acceleration. Default to 0.02.

  • goalVelocity (double): Goal velocity. Default to 0.5.

  • goalAccel (double): Goal acceleration. Default to 0.02.

  • maxAccel (double): Max acceleration. Default to 1.5.

  • maxJerk (double): Max jerk. Default to 0.3.

  • step (double): Step. Default to 0.16666666667.

Outputs

  • execOut (execution): The output execution.

  • pathArrays (double[]): The path v, x, y, and yaw arrays.

  • target (double[3]): Target position and orientation.

  • targetChanged (bool): Target position/orientation has changed.

HolonomicController

Holonomic Controller

Calculating the desired wheel speeds when given a desired vehicle speed.

Inputs

  • execIn (execution): The input execution.

  • wheelRadius (double[]): an array of wheel radius.

  • wheelPositions (double[3][]): position of the wheel with respect to chassis’ center of mass.

  • wheelOrientations (double[4][]): orientation of the wheel with respect to chassis’ center of mass frame.

  • mecanumAngles (double[]): angles of the mecanum wheels with respect to wheel’s rotation axis.

  • wheelAxis (double[3]): the rotation axis of the wheels.

  • upAxis (double[3]): the rotation axis of the vehicle.

  • velocityCommands ([‘float[3]’, ‘double[3]’]): velocity in x and y and rotation.

  • maxLinearSpeed (double, optional): maximum speed allowed for the vehicle.

  • maxAngularSpeed (double, optional): maximum angular rotation speed allowed for the vehicle.

  • maxWheelSpeed (double, optional): maximum rotation speed allowed for the wheel joints.

  • linearGain (double): linear gain. Default to 1.

  • angularGain (double): angular gain. Default to 1.

Outputs

  • jointPositionCommand (double[]): position commands for the wheel joints.

  • jointVelocityCommand (double[]): velocity commands for the wheels joints.

  • jointEffortCommand (double[]): effort commands for the wheels joints.

StanleyControlPID

Drive to Target Steering

Inputs

  • execIn (execution): The input execution.

  • currentPosition (vectord[3]): Current position of the robot (recommended to use Get Prim Local to World Transform node).

  • currentOrientation (quatd[4]): Current rotation of the robot as a quaternion (recommended to use Get Prim Local to World Transform node).

  • currentSpeed (vectord[3]): Current linear velocity of the robot.

  • maxVelocity (double): Maximum linear velocity of the robot. Default to 1.5.

  • reachedGoal (bool[]): Position and orientation thresholds at target. Default to [False, False].

  • pathArrays (double[]): The path v, x, y, and yaw arrays.

  • target (double[3]): Target position and orientation. Default to [0, 0, 0].

  • targetChanged (bool): Target position/orientation has changed. Default to False.

  • wheelBase (double): Distance between the centers of the front and rear wheels. Default to 0.4132.

  • thresholds (double[2]): Position and orientation thresholds at target. Default to [0.1, 0.1].

  • drawPath (bool): Draw the provided path curve onto the stage. Default to False.

  • step (double): Step. Default to 0.16666666667.

  • gains (double[3]): control, velocity and steering gains. Default to [0.5, 0.1, 0.0872665].

Outputs

  • execOut (execution): The output execution.

  • linearVelocity (double): Current forward speed for robot drive.

  • angularVelocity (double): Current angular speed for robot drive.

HolonomicRobotUsdSetup

setup any robot to be ready to be used by the holonomic controller by extract attributes from USD

Use this node to extract all the holonomic drive information from USD if the listed information are stored in the USD file already. If they are not in USD, you can manually set those values in the HolonomicController node

Inputs

  • robotPrim (target): prim for the robot’s articulation root.

  • comPrim (target): prim for the center of mass xform.

  • usePath (bool): use prim path instead of prim target. Default to False.

  • robotPrimPath (token): prim path to the robot’s articulation root link when usdPath is true.

  • comPrimPath (token): prim path to the robot’s center of mass xform.

Outputs

  • wheelRadius (double[]): an array of wheel radius.

  • wheelPositions (double[3][]): position of the wheel with respect to chassis’ center of mass.

  • wheelOrientations (double[4][]): orientation of the wheel with respect to chassis’ center of mass frame.

  • mecanumAngles (double[]): angles of the mechanum wheels with respect to wheel’s rotation axis.

  • wheelAxis (double[3]): the rotation axis of the wheels, assuming all wheels have the same.

  • upAxis (double[3]): the rotation axis of the vehicle.

  • wheelDofNames (token[]): name of the left wheel joint.

CheckGoal2D

Check if wheeled robot has reached goal

Inputs

  • execIn (execution): The input execution.

  • currentPosition (vectord[3]): Current position of the robot (recommended to use Get Prim Local to World Transform node).

  • currentOrientation (quatd[4]): Current rotation of the robot as a quaternion (recommended to use Get Prim Local to World Transform node).

  • target (double[3]): Target position and orientation. Default to [0, 0, 0].

  • targetChanged (bool): Target position/orientation has changed. Default to False.

  • thresholds (double[2]): Position and orientation thresholds at target. Default to [0.1, 0.1].

Outputs

  • execOut (execution): The output execution.

  • reachedGoal (bool[]): Reached position and orientation goals.

AckermannSteering

Ackermann Steering Geometry

Inputs

  • execIn (execution): The input execution.

  • accel (double): Desired acceleration for the robot.

  • curvature (double): Desired curvature for the robot, equal to 1/radius of curvature. By default it is positive for turning right and negative for turning left for front wheel drive.

  • linearVelocity (vectord[3]): Current linear velocity of the robot.

  • wheelBase (double): Distance between the front and rear axles of the robot.

  • trackWidth (double): Distance between the left and right rear wheels of the robot.

  • turningWheelRadius (double): Radius of the front wheels of the robot.

  • maxWheelVelocity (double): Maximum angular velocity of the robot wheel (rad/s).

  • invertCurvature (bool): Flips the sign of the curvature, Set to true for rear wheel drive.

  • maxWheelRotation (double): Maximum angle of rotation for the front wheels in degrees.

  • DT (double): Delta time for the simulation step.

Outputs

  • execOut (execution): The output execution.

  • leftWheelAngle (double): Angle for the left turning wheel in degrees.

  • rightWheelAngle (double): Angle for the right turning wheel in degrees.

  • wheelRotationVelocity (double): Angular velocity for the turning wheels in rad/s.