mbodied.types.motion package

Submodules

mbodied.types.motion.control module

class mbodied.types.motion.control.FullJointControl(datum=None, *, joints: Sequence[JointControl] | list[float] = None, names: Sequence[str] | list[float] | None = None)

Bases: Motion

Full joint control.

joints: Sequence[JointControl] | list[float]

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'joints': FieldInfo(annotation=Union[Sequence[JointControl], list[float]], required=False, default_factory=list, description='List of joint values in radians. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'names': FieldInfo(annotation=Union[Sequence[str], list[float], NoneType], required=False, default=None, description='List of joint names. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

names: Sequence[str] | list[float] | None

space()

Return the corresponding Gym space for the Sample instance based on its instance attributes. Omits None values.

Override this method in subclasses to customize the space generation.

class mbodied.types.motion.control.HandControl(datum=None, *, pose: Pose6D = None, grasp: JointControl = None)

Bases: Motion

Action for a 7D space representing x, y, z, roll, pitch, yaw, and oppenness of the hand.

grasp: JointControl

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'grasp': FieldInfo(annotation=JointControl, required=False, default_factory=JointControl, description='Openness of the robot hand. 0 is closed, 1 is open. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'pose': FieldInfo(annotation=Pose6D, required=False, default_factory=Pose, description='Pose of the robot hand. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

pose: Pose6D

class mbodied.types.motion.control.HeadControl(datum=None, *, tilt: JointControl = None, pan: JointControl = None)

Bases: Motion

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'pan': FieldInfo(annotation=JointControl, required=False, default_factory=<lambda>, description='Pan of the robot head in radians (left is negative). Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'tilt': FieldInfo(annotation=JointControl, required=False, default_factory=<lambda>, description='Tilt of the robot head in radians (down is negative). Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

pan: JointControl

tilt: JointControl

class mbodied.types.motion.control.HumanoidControl(datum=None, *, left_arm: FullJointControl | None = None, right_arm: FullJointControl | None = None, left_leg: FullJointControl | None = None, right_leg: FullJointControl | None = None, head: HeadControl | None = None)

Bases: Motion

Control for a humanoid robot.

head: HeadControl | None

left_arm: FullJointControl | None

left_leg: FullJointControl | None

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'head': FieldInfo(annotation=Union[HeadControl, NoneType], required=False, default=None, description='Control for the robot head. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'left_arm': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the left robot arm. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'left_leg': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the left robot leg. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'right_arm': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the right robot arm. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'right_leg': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the right robot leg. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

right_arm: FullJointControl | None

right_leg: FullJointControl | None

class mbodied.types.motion.control.JointControl(datum=None, *, value: float = None)

Bases: Motion

Motion for joint control.

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'value': FieldInfo(annotation=float, required=False, default_factory=<lambda>, description='Joint value in radians. Bounds: [-3.14, 3.14] Motion type: UNSPECIFIED', json_schema_extra={'bounds': [-3.14, 3.14], 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

space()

Return the corresponding Gym space for the Sample instance based on its instance attributes. Omits None values.

Override this method in subclasses to customize the space generation.

value: float

class mbodied.types.motion.control.LocobotActionOrAnswer(datum=None, *, base: LocationAngle | None = None, hand: HandControl | None = None, head: HeadControl | None = None, answer: str | None = '', sleep: bool | None = False, home: bool | None = False)

Bases: MobileSingleHandControl

answer: str | None

home: bool | None

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'answer': FieldInfo(annotation=Union[str, NoneType], required=False, default='', description='Short, one sentence answer to any question a user might have asked. 20 words max.'), 'base': FieldInfo(annotation=Union[LocationAngle, NoneType], required=False, default_factory=LocationAngle, description='Location of the robot on the ground. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'hand': FieldInfo(annotation=Union[HandControl, NoneType], required=False, default_factory=HandControl, description='Control for the robot hand. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'head': FieldInfo(annotation=Union[HeadControl, NoneType], required=False, default=None, description='Control for the robot head. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'home': FieldInfo(annotation=Union[bool, NoneType], required=False, default=False, description='Whether the robot should go to home after executing the motion.'), 'sleep': FieldInfo(annotation=Union[bool, NoneType], required=False, default=False, description='Whether the robot should go to sleep after executing the motion.')}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

sleep: bool | None

class mbodied.types.motion.control.MobileBimanualArmControl(datum=None, *, base: LocationAngle | None = None, left_arm: FullJointControl | None = None, right_arm: FullJointControl | None = None, head: HeadControl | None = None)

Bases: Motion

Control for a robot that can move in 2D space with two arms.

base: LocationAngle | None

head: HeadControl | None

left_arm: FullJointControl | None

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'base': FieldInfo(annotation=Union[LocationAngle, NoneType], required=False, default_factory=LocationAngle, description='Location of the robot on the ground. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'head': FieldInfo(annotation=Union[HeadControl, NoneType], required=False, default=None, description='Control for the robot head. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'left_arm': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the left robot arm. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'right_arm': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the right robot arm. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

right_arm: FullJointControl | None

class mbodied.types.motion.control.MobileSingleArmControl(datum=None, *, base: LocationAngle | None = None, arm: FullJointControl | None = None, head: HeadControl | None = None)

Bases: Motion

Control for a robot that can move in 2D space with a single arm.

arm: FullJointControl | None

base: LocationAngle | None

head: HeadControl | None

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'arm': FieldInfo(annotation=Union[FullJointControl, NoneType], required=False, default_factory=FullJointControl, description='Control for the robot arm. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'base': FieldInfo(annotation=Union[LocationAngle, NoneType], required=False, default_factory=LocationAngle, description='Location of the robot on the ground. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'head': FieldInfo(annotation=Union[HeadControl, NoneType], required=False, default=None, description='Control for the robot head. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

class mbodied.types.motion.control.MobileSingleHandControl(datum=None, *, base: LocationAngle | None = None, hand: HandControl | None = None, head: HeadControl | None = None)

Bases: Motion

Control for a robot that can move its base in 2D space with a 6D EEF control + grasp.

base: LocationAngle | None

hand: HandControl | None

head: HeadControl | None

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {'base': FieldInfo(annotation=Union[LocationAngle, NoneType], required=False, default_factory=LocationAngle, description='Location of the robot on the ground. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'hand': FieldInfo(annotation=Union[HandControl, NoneType], required=False, default_factory=HandControl, description='Control for the robot hand. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None}), 'head': FieldInfo(annotation=Union[HeadControl, NoneType], required=False, default=None, description='Control for the robot head. Motion type: UNSPECIFIED', json_schema_extra={'bounds': None, 'motion_type': 'UNSPECIFIED', 'shape': None})}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

mbodied.types.motion.motion module

This module contains the base class for a motion.

There are four basic motion types that are supported: - Absolute motion: The desired absolute coordinates of a limb or joint in the chosen reference frame. - Relative motion: The displacement from the current position of a limb or joint (frame-independent). - Velocity motion: The desired absolute velocity of a limb or joint (frame-independent). - Torque motion: The desired torque of a limb or joint (frame-independent).

The bounds is a list of two floats representing the lower and upper bounds of the motion. The shape is a tuple of integers representing the shape of the motion. The reference_frame is a string representing the reference frame for the coordinates (only applies to absolute motions).

To create a new Pydantic model for a motion, inherit from the Motion class and define pydantic fields with the MotionField, function as you would with any other Pydantic field.

Example

from mbodied_agents.motion import Motion, AbsoluteMotionField, MotionField, MotionType, VelocityMotionField from mbodied_agents.data.sample import Sample

class Twist(Motion):

x: float = VelocityMotionField(default=0.0, bounds=[-1.0, 1.0]) y: float = VelocityMotionField(default=0.0, bounds=[-1.0, 1.0]) z: float = VelocityMotionField(default=0.0, bounds=[-1.0, 1.0]) roll: float = VelocityMotionField(default=0.0, bounds=[‘-pi’, ‘pi’]) pitch: float = VelocityMotionField(default=0.0, bounds=[‘-pi’, ‘pi’]) yaw: float = VelocityMotionField(default=0.0, bounds=[‘-pi’, ‘pi’])

This automatically generates a Pydantic model with the specified fields and the additional properties of a motion. It is vectorizable, serializable, and validated according to its type. Furthermore, convience methods from the class allow for direct conversion to numpy, pytorch, and gym spaces. See the Sample class documentation for more information: https://mbodi-ai-mbodied-agents.readthedocs-hosted.com/en/latest/ See the Pydantic documentation for more information on how to define Pydantic models: https://pydantic-docs.helpmanual.io/

mbodied.types.motion.motion.AbsoluteMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for an absolute motion.

This field is used to define the shape and bounds of an absolute motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

class mbodied.types.motion.motion.Motion(datum=None)

Bases: Sample

Base class for a motion.

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

mbodied.types.motion.motion.MotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, motion_type: Literal['UNSPECIFIED', 'OTHER', 'ABSOLUTE', 'RELATIVE', 'VELOCITY', 'TORQUE'] = 'UNSPECIFIED', **kwargs) → Any

Field for a motion.

Parameters:

• default – Default value for the field.

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

• motion_type – Type of the motion. Can be “UNSPECIFIED”, “OTHER”, “ABSOLUTE”, “RELATIVE”, “VELOCITY”, “TORQUE”.

mbodied.types.motion.motion.OtherMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for an other motion.

This field is used to define the shape and bounds of an other motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.motion.RelativeMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a relative motion.

This field is used to define the shape and bounds of a relative motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.motion.TorqueMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a torque motion.

This field is used to define the shape and bounds of a torque motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.motion.VelocityMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a velocity motion.

This field is used to define the shape and bounds of a velocity motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

Module contents

mbodied.types.motion.AbsoluteMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for an absolute motion.

This field is used to define the shape and bounds of an absolute motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

class mbodied.types.motion.Motion(datum=None)

Bases: Sample

Base class for a motion.

model_computed_fields: ClassVar[dict[str, ComputedFieldInfo]] = {}

A dictionary of computed field names and their corresponding ComputedFieldInfo objects.

model_config: ConfigDict = {'arbitrary_types_allowed': True, 'extra': 'forbid', 'from_attributes': True, 'use_enum_values': False, 'validate_assignment': False}

Configuration for the model, should be a dictionary conforming to [ConfigDict][pydantic.config.ConfigDict].

model_fields: ClassVar[dict[str, FieldInfo]] = {}

Metadata about the fields defined on the model, mapping of field names to [FieldInfo][pydantic.fields.FieldInfo].

This replaces Model.__fields__ from Pydantic V1.

mbodied.types.motion.MotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, motion_type: Literal['UNSPECIFIED', 'OTHER', 'ABSOLUTE', 'RELATIVE', 'VELOCITY', 'TORQUE'] = 'UNSPECIFIED', **kwargs) → Any

Field for a motion.

Parameters:

• default – Default value for the field.

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

• motion_type – Type of the motion. Can be “UNSPECIFIED”, “OTHER”, “ABSOLUTE”, “RELATIVE”, “VELOCITY”, “TORQUE”.

mbodied.types.motion.OtherMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for an other motion.

This field is used to define the shape and bounds of an other motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.RelativeMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a relative motion.

This field is used to define the shape and bounds of a relative motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.TorqueMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a torque motion.

This field is used to define the shape and bounds of a torque motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.

mbodied.types.motion.VelocityMotionField(default: Any = PydanticUndefined, bounds: list[float] | None = None, shape: tuple[int] | None = None, description: str | None = None, **kwargs) → Any

Field for a velocity motion.

This field is used to define the shape and bounds of a velocity motion.

Parameters:

• bounds – Bounds of the motion.

• shape – Shape of the motion.

• description – Description of the motion.