Coordinate System Transformations#

class Direction#

Bases: ndarray

A cartesian unit norm vector pointing towards a direction.

classmethod From_Spherical(azimuth, zenith)#

Initialize a direction from spherical parameters.

Parameters:

azimuth (float) – Azimuth angle in radians.
zenith (float) – Zenith angle in radians.

Return type:

Direction

Returns: The initialized direction.

to_spherical()#

Represent the direction as spherical coordinates.

Returns: An array representing azimuth and zenith angles in radians.

Return type:: ndarray

classmethod From_Cartesian(vector, normalize=False)#

Initialize a direction from a cartesian vector.

Raises:: ValueError – If vector does not represent a valid cartesian vector.

Returns: The initialized direction.

Return type:: Direction

class Transformation#

Bases: ndarray, Serializable

Coordinate system transformation.

yaml_tag: Optional[str] = 'Transformation'#: YAML serialization tag.

property translation: ndarray#

property rotation_rpy: ndarray#

Orientation in Roll, Pitch and Yaw Angles.

Returns: Roll, Pitch and Yaw in Radians.

classmethod No()#

Return type:: Transformation

classmethod From_RPY(rpy, pos)#

Return type:: Transformation

classmethod From_Translation(translation)#

Return type:: Transformation

transform_position(position)#

Transform a cartesian position.

Parameters:: position (np.ndarray) – Numpy array representing the cartesian position.
Return type:: ndarray

Returns: The transformed position.

Raises:: ValueError – If position is invalid.

rotate_direction(direction)#

Rotate a cartesian direction.

Parameters:: direction (np.ndarray) – A directional vector.
Return type:: Direction

Returns: The transformed direction.

Raises:: ValueError – If direction is invalid.

transform_direction(direction, normalize=False)#

Transform a direction.

Parameters:

direction (np.ndarray) – Direction to be transformed.
normalize (bool, optional) – Normalize the resulting transformed direction to a unit norm vector. Disabled by default.

Return type:

Direction

Returns: The transformed direction.

classmethod to_yaml(representer, node)#

Serialize a serializable object to YAML.

Parameters:

representer (SafeRepresenter) – A handle to a representer used to generate valid YAML code. The representer gets passed down the serialization tree to each node.
node (Serializable) – The channel instance to be serialized.

Return type:

MappingNode

Returns: The serialized YAML node.

classmethod from_yaml(constructor, node)#

Recall a new serializable class instance from YAML.

Parameters:

constructor (SafeConstructor) – A handle to the constructor extracting the YAML information.
node (Node) – YAML node representing the Serializable serialization.

Return type:

Transformation

Returns: The de-serialized object.

class TransformableLink#

Bases: object

Abstract base class of kinetmatic chain links.

abstract property forwards_transformation: Transformation#

Transformation to convert local coordinates to global coordinates.

Updated every time the kinematic chain’s parameters change.

Returns: The transformation.

abstract set_base(base)#

Set the relative base coordinate frame of this link.

Parameters:: base (TransformableLink | None) – The base to be coordinate frame to be set. None to detach the link.
Return type:: None

property linked_frames: Set[TransformableLink]#

add_link(link)#

Establish a new link to a coordinate frame depending on this frame.

Parameters:: link (Transformable) – The transformable frame to be registered.
Return type:: None

remove_link(link, force_removal=True)#

Remove an established link to this coordinate frame.

Parameters:

link (Transformable) – The coordinate frame to be linked to this frame.
force_removal (bool, optional) – Raise a RuntimeError if the link is not registered

Raises:

RuntimeError – If the link is not currently registerd and force_removal is enabled.

Return type:

None

class TransformableBase#

Bases: TransformableLink

Base of kinematic chains.

property forwards_transformation: Transformation#

Transformation to convert local coordinates to global coordinates.

Updated every time the kinematic chain’s parameters change.

Returns: The transformation.

set_base(base)#

Set the relative base coordinate frame of this link.

Parameters:: base (TransformableLink | None) – The base to be coordinate frame to be set. None to detach the link.
Return type:: None

class Transformable(pose=None)#

Bases: Serializable, TransformableLink

Representation of a Coordinate Frame within a Kinematic Chain.

Parameters:: pose (Transformation, optional) – Transformation of the transformable with respect to its reference frame. By default, no transformation is considered, i.e. Transformation.No()

property_blacklist: Set[str] = {'pose'}#: Set of properties to be ignored during serialization.

property position: ndarray#

Position of the Transformable.

Cartesian offset to the reference coordinate frame.

Returns:: Cartesian position x, y, z in m.
Raises:: ValueError – If position is not a valid three-dimensional vector.

property orientation: ndarray#

Orientation of the Transformable.

Returns: The transformation in radians for roll, pitch and yaw.

Raises:: ValueError – If orientation is not a three-dimensional numpy vector.

set_base(base)#

Set the relative base coordinate frame of this link.

Parameters:: base (TransformableLink | None) – The base to be coordinate frame to be set. None to detach the link.
Return type:: None

property global_position: ndarray#

Position of the represented object within the global coordinate system.

Returns: Three-dimensional numpy vector representing the cartesian object coordinates.

property global_orientation: ndarray#

Orientation of the represented object within the global coordinate system.

Returns: Three-dimensional numpy vector representing roll, pitch and yaw in radians.

property is_base: bool#

Is this transformable acting as a base frame?

Returns: Boolean indicator.

property pose: Transformation#

Pose of the Transformable with respect to its reference link.

Returns: The pose’s transformation.

property forwards_transformation: Transformation#

Transformation to convert local coordinates to global coordinates.

Updated every time the kinematic chain’s parameters change.

Returns: The transformation.

property backwards_transformation: Transformation#

Transformation to convert global coordinates to local coordinates.

Updated every time the kinematic chain’s parameters change.

Returns: The transformation.

to_local_coordinates(arg_0, arg_1=None)#

Return type:: Transformation