Motion Service

Parameters:

• component_name (ResourceName): The ResourceName of the piece of the robot that should arrive at the destination. Note that move moves the distal end of the component to the destination. For example, when moving a robotic arm, the piece that will arrive at the destination is the end effector attachment point, not the base of the arm.

• destination (PoseInFrame): Describes where the component_name frame should be moved to. Can be any pose, from the perspective of any component whose location is configured as a frame.

  Note that the destination pose is relative to the distal end of the specified frame. This means that if the destination is the same as the component_name frame, for example an arm’s frame, then a pose of {X: 10, Y: 0, Z: 0} will move that arm’s end effector by 10 mm in the local X direction.

• world_state (WorldState) (optional): Data structure specifying information about the world around the machine. Used to augment the motion solving process. world_state includes obstacles and transforms:

  • Obstacles: Geometries located at a pose relative to some frame. When solving a motion plan with movable frames that contain inherent geometries, the solved path is constrained such that none of those inherent geometries intersect with the obstacles. Important considerations:
    • If a motion begins with a component already in collision with an obstacle, collisions between that specific component and that obstacle will not be checked.
    • The motion service assumes that obstacles are static. If a worldstate obstacle is physically attached to a part of the robot such that it will move with the robot, specify it with transforms.
    • Obstacles are defined by a pose and a geometry with dimensions. The pose location is the point at the center of the geometry.
    • Obstacle locations are defined with respect to the origin of the specified frame. Their poses are relative to the origin of the specified frame. An obstacle associated with the frame of an arm with a pose of {X: 0, Y: 0, Z: -10} is interpreted as being 10mm below the base of the arm, not 10mm below the end effector. This is different from destination and component_name, where poses are relative to the distal end of a frame.
  • Transforms: A list of PoseInFrame messages that specify other transformations to temporarily add to the frame system at solve time. Transforms can be used to account for geometries that are attached to the robot but not configured as robot components. For example, you could use a transform to represent the volume of a marker held in your machine’s gripper. Transforms are not added to the config or carried into later processes.

• constraints (Constraints) (optional): Pass in motion constraints. By default, motion is unconstrained with the exception of obstacle avoidance.

• extra (Mapping[str, Any]) (optional): A generic struct, containing extra options to pass to the underlying RPC call.

Returns:

• (bool): Whether the move was successful.

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")

# Assumes a gripper configured with name "my_gripper" on the machine
gripper_name = Gripper.get_resource_name("my_gripper")
my_frame = "my_gripper_offset"

goal_pose = Pose(x=0, y=0, z=300, o_x=0, o_y=0, o_z=1, theta=0)

# Move the gripper
moved = await motion.move(component_name=gripper_name,
                          destination=PoseInFrame(reference_frame="myFrame",
                                                  pose=goal_pose),
                          world_state=worldState,
                          constraints={},
                          extra={})

Parameters:

• component_name (ResourceName): The ResourceName of the piece of the machine whose pose is returned.

• destination_frame (str): The name of the frame with respect to which the component’s pose is reported.

• supplemental_transforms (Optional[List[Transforms]]) (optional): A list of Transform objects. A Transform represents an additional frame which is added to the machine’s frame system. It consists of the following fields:

  • pose_in_observer_frame: Provides the relationship between the frame being added and another frame.
  • physical_object: An optional Geometry can be added to the frame being added.
  • reference_frame: Specifies the name of the frame which will be added to the frame system.

  When supplemental_transforms are provided, a frame system is created within the context of the GetPose function. This new frame system builds off the machine’s frame system and incorporates the Transforms provided. If the result of adding the Transforms results in a disconnected frame system, an error is thrown.

• extra (Mapping[str, Any]) (optional): A generic struct, containing extra options to pass to the underlying RPC call.

Returns:

• (PoseInFrame): The pose of the component.

For more information, see the Python SDK Docs.

The following code example gets the pose of the tip of a gripper named my_gripper which is attached to the end of an arm, in the “world” reference_frame:

from viam.components.gripper import Gripper
from viam.services.motion import MotionClient

# Assume that the connect function is written and will return a valid machine.
robot = await connect()

motion = MotionClient.from_robot(robot=robot, name="builtin")
gripperName = Gripper.get_resource_name("my_gripper")
gripperPoseInWorld = await motion.get_pose(component_name=gripperName,
                                           destination_frame="world")

For a more complicated example, take the same scenario and get the pose of the same gripper with respect to an object situated at a location (100, 200, 0) relative to the “world” frame:

from viam.components.gripper import Gripper
from viam.services.motion import MotionClient
from viam.proto.common import Transform, PoseInFrame, Pose

# Assume that the connect function is written and will return a valid machine.
robot = await connect()

motion = MotionClient.from_robot(robot=robot, name="builtin")
objectPose = Pose(x=100, y=200, z=0, o_x=0, o_y=0, o_z=1, theta=0)
objectPoseInFrame = PoseInFrame(reference_frame="world", pose=objectPose)
objectTransform = Transform(reference_frame="object",
                            pose_in_observer_frame=objectPoseInFrame)
gripperName = Gripper.get_resource_name("my_gripper")
gripperPoseInObjectFrame = await motion.get_pose(
  component_name=gripperName,
  destination_frame="world",
  supplemental_transforms=objectTransform
)

Parameters:

• component_name (ResourceName): The ResourceName of the base to move.
• destination (Pose): The destination, which can be any Pose with respect to the SLAM map’s origin.
• slam_service_name (ResourceName): The ResourceName of the SLAM service from which the SLAM map is requested.
• configuration (Optional[MotionConfiguration]): The configuration you want to set across this machine for this motion service. This parameter and each of its fields are optional.
  • obstacle_detectors (Iterable[ObstacleDetector]): The names of each vision service and camera resource pair you want to use for transient obstacle avoidance.
  • position_polling_frequency_hz (float): The frequency in hz to poll the position of the machine.
  • obstacle_polling_frequency_hz (float): The frequency in hz to poll the vision service for new obstacles.
  • plan_deviation_m (float): The distance in meters that the machine can deviate from the motion plan. By default this is set to 2.6 m which is an appropriate value for outdoor usage. When you use the MoveOnMap() method from the CONTROL tab, the default is overwritten to 0.5 m for testing.
  • linear_m_per_sec (float): Linear velocity this machine should target when moving.
  • angular_degs_per_sec (float): Angular velocity this machine should target when turning.
• obstacles Optional[Iterable[Geometry]]: Obstacles, specified in the SLAM frame coordinate system, to be considered when planning the motion of the component.
• extra (Optional[Dict[str, Any]]): Extra options to pass to the underlying RPC call.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (str): ExecutionID of the MoveOnMap call.

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")

# Get the ResourceNames of the base and SLAM service
my_base_resource_name = Base.get_resource_name("my_base")
my_slam_service_name = SLAMClient.get_resource_name("my_slam_service")

# Define a destination pose with respect to the origin of the map from the SLAM
# service "my_slam_service"
my_pose = Pose(y=10)

# Move the base component to the destination pose of Y=10, a location of
# (0, 10, 0) in respect to the origin of the map
execution_id = await motion.move_on_map(component_name=my_base_resource_name,
                                        destination=my_pose,
                                        slam_service_name=my_slam_service_name)

Parameters:

• component_name (ResourceName): The ResourceName of the base to move.
• destination (GeoPoint): The location of the component’s destination, represented in geographic notation as a GeoPoint (lat, lng).
• movement_sensor_name (ResourceName): The ResourceName of the movement sensor that you want to use to check the machine’s location.
• obstacles (Optional[Sequence[GeoObstacle]]): Obstacles to consider when planning the motion of the component, with each represented as a GeoObstacle.
  • Default: None
• heading (Optional[float]): The compass heading, in degrees, that the machine’s movement sensor should report at the destination point.
  • Range: [0-360) 0: North, 90: East, 180: South, 270: West
  • Default: None
• configuration (Optional[MotionConfiguration]): The configuration you want to set across this machine for this motion service. This parameter and each of its fields are optional.
  • obstacle_detectors (Iterable[ObstacleDetector]): The names of each vision service and camera resource pair you want to use for transient obstacle avoidance.
  • position_polling_frequency_hz (float): The frequency in hz to poll the position of the machine.
  • obstacle_polling_frequency_hz (float): The frequency in hz to poll the vision service for new obstacles.
  • plan_deviation_m (float): The distance in meters that the machine can deviate from the motion plan.
  • linear_m_per_sec (float): Linear velocity this machine should target when moving.
  • angular_degs_per_sec (float): Angular velocity this machine should target when turning.
• extra (Optional[Dict[str, Any]]): Extra options to pass to the underlying RPC call.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (str): ExecutionID of the MoveOnGlobe call.

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")

# Get the ResourceNames of the base and movement sensor
my_base_resource_name = Base.get_resource_name("my_base")
mvmnt_sensor_resource_name = MovementSensor.get_resource_name(
    "my_movement_sensor")
#  Define a destination GeoPoint at the GPS coordinates [0, 0]
my_destination = movement_sensor.GeoPoint(latitude=0, longitude=0)

# Move the base component to the designated geographic location, as reported by
# the movement sensor
execution_id = await motion.move_on_globe(
    component_name=my_base_resource_name,
    destination=my_destination,
    movement_sensor_name=mvmnt_sensor_resource_name)

Parameters:

• component_name (ResourceName): The ResourceName of the base to stop.
• extra (Optional[Dict[str, Any]]): Extra options to pass to the underlying RPC call.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (None)

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")
my_base_resource_name = Base.get_resource_name("my_base")

# Assuming a move_on_globe started started the execution
# mvmnt_sensor = MovementSensor.get_resource_name("my_movement_sensor")
# my_destination = movement_sensor.GeoPoint(latitude=0, longitude=0)
# execution_id = await motion.move_on_globe(
#    component_name=my_base_resource_name,
#    destination=my_destination,
#    movement_sensor_name=mvmnt_sensor_resource_name)

# Stop the base component which was instructed to move by `MoveOnGlobe()`
# or `MoveOnMap()`
my_base_resource_name = Base.get_resource_name("my_base")
await motion.stop_plan(component_name=mvmnt_sensor)

Parameters:

• component_name (ResourceName): The ResourceName of the base to stop.
• lastPlanOnly (Optional[bool]): If true, the response will only return the the last plan for the component. If the executionID parameter is non empty then the last plan for the component & executionID is returned.
• executionID (Optional[str]): If non empty, the response will return the plans of the provided execution & component. Useful for retrieving plans from executions before the current execution.
• extra (Optional[Dict[str, Any]]): Extra options to pass to the underlying RPC call.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (GetPlanResponse)
  • current_plan_with_status: The current plan and status that matches the request query
  • replan_history: The history of all previous plans that were generated in ascending order. This field will be empty if the motion service did not need to re-plan.

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")
my_base_resource_name = Base.get_resource_name("my_base")
# Get the plan(s) of the base component which was instructed
# to move by `MoveOnGlobe()` or `MoveOnMap()`
resp = await motion.get_plan(component_name=my_base_resource_name)

Parameters:

• onlyActivePlans (Optional[bool]): If true, the response will only return plans which are executing.
• extra (Optional[Dict[str, Any]]): Extra options to pass to the underlying RPC call.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (ListPlanStatusesResponse)
  • (plan_statuses_with_ids): List of plan statuses along with associated planId, componentName and executionID that match the request.

For more information, see the Python SDK Docs.

motion = MotionClient.from_robot(robot=robot, name="builtin")
# List the plan statuses of the motion service within the TTL
resp = await motion.list_plan_statuses()

Parameters:

• command (Mapping[str, ValueTypes]): The command to execute.
• timeout (Optional[float]): An option to set how long to wait (in seconds) before calling a time-out and closing the underlying RPC call.

Returns:

• (Mapping[str, ValueTypes]): Result of the executed command.

For more information, see the Python SDK Docs.

# Access the motion service
motion = MotionClient.from_robot(robot=robot, name="builtin")

my_command = {
  "command": "dosomething",
  "someparameter": 52
}

await motion.do_command(my_command)

Parameters:

• None

Returns:

• None

motion = MotionClient.from_robot(robot, "builtin")

await motion.close()

For more information, see the Python SDK Docs.