Motion Service

The class xamla_motion.motion_service.MotionService implements the low level service and action calls to communicate with the xamlamoveit server part.

Warning

The class xamla_motion.motion_service.MotionService is only documented for completeness. The functionalities of this class are wrapped by the specific clients to be more user-friendly. Please, only use these specific client implementation and not directly the motion services.

class xamla_motion.motion_service.MotionService

classmethod create_plan_parameters(move_group_name=None, joint_set=None, max_velocity=None, max_acceleration=None, **kwargs)

Create PlanParameters from user defined and/or quried inputs

Parameters

• move_group_name (str (optional default query first)) – move group for which plan parameters should be created

• joint_set (JointSet (optional default query similar)) – joint set for which plan parameters should be created

• max_velocity (Iterable[float convertable] (optional default max query)) – Defines the maximal velocity for every joint

• max_acceleration (Iterable[float convertable] (op default max query)) – Defines the maximal acceleration for every joint

• kwargs (dict) –

  sample_resolutionfloat convertable (optional default 0.008/125Hz)

  sample points frequency if value is create as 1.0 the value is interpreted as a value in seconds else the value is interpreted as a value in Hz

  collision_checkbool convertable (optional default True)

  check for collision if True

  max_deviationfloat convertable (optional default 0.2)

  max deviation from fly by points

  velocity_scalingfloat convertable (optional default 1.0)

  scale query or user defined max velocity values between 0.0 and 1.0

  acceleration_scalingfloat convertable (optional default 1.0)

  scale query or user defined max acceleration values between 0.0 and 1.0

Returns

Instance of plan parameters with automatically queried and/or user defined values

Return type

PlanParameters

Raises

• ServiceException – If query services are not reachable or not finish successful

• TypeError – If move group name is not of type None or str convertable If joint_set is not of type None or JointSet If an other parameter is not convertable

• ValueError – If scaling parameters are not between 0.0 and 1.0

• ArgumentError – If a argument is not set and also could not be quired automatically

classmethod create_task_space_plan_parameters(end_effector_name=None, max_xyz_velocity=None, max_xyz_acceleration=None, max_angular_velocity=None, max_angular_acceleration=None, **kwargs)

Creates TakesSpacePlanParameters from user defined or queried inputs

Parameters

• move_group_name (str (optional default query first)) – move group for which plan parameters should be created

• max_xyz_velocity (float convertable or None) – Defines the maximal xyz velocity [m/s]

• max_xyz_acceleration (float convertable) – Defines the maximal xyz acceleration [m/s^2]

• max_angular_velocity (float convertable or None) – Defines the maximal angular velocity [rad/s]

• max_angular_acceleration (float convertable or None) – Defines the maximal angular acceleration [rad/s^2]

• kwargs (dict) –

  sample_resolutionfloat convertable (optional default 0.008/125Hz)

  sample points frequency if value is create as 1.0 the value is interpreted as a value in seconds else the value is interpreted as a value in Hz

  collision_checkbool convertable (optional default True)

  check for collision if True

  ik_jump_thresholdfloat convertable (optional default 1.2)

  maximal inverse kinematic jump

  max_deviationfloat convertable (optional default 0.2)

  max deviation from fly by points

  velocity_scalingfloat convertable (optional default 1.0)

  scale query or user defined max velocity values between 0.0 and 1.0

  acceleration_scalingfloat convertable (optional default 1.0)

  scale query or user defined max acceleration values between 0.0 and 1.0

Returns

Instance of TaskSpacePlanParameters with automatically queried and/or user defined values

Return type

TaskSpacePlanParameters

Raises

• ServiceException – If query services are not reachable or not finish successful

• TypeError – If end_effector_name is not of type None or str convertable If an other parameter is not convertable

• ValueError – If scaling parameters are not between 0.0 and 1.0

• ArgumentError – If a argument is not set and also could not be quired automatically

classmethod emergency_stop(enable=True)

Sets and resets emergency stop

Parameters

enable (bool convertable (default True)) – If True activate emergency stop If False resets the emergency stop

Returns

• success (bool) – True if the service call was successful

• message (str) – Response or error message

Raises

• TypeError – If enable is not convertable to bool

• ServiceException – If query service is not available

execute_joint_trajectory(trajectory, collision_check)

Executes a joint trajectory

Parameters

• trajectory (JointTrajectory) – Joint trajectory which should be executed

• collision_check (bool convertable) – If True check for collision while executing

Raises

• TypeError – If trajectory is not of type JointTrajectory or if collision_check is not convertable to bool

• ServiceException – If execution ends not successful

execute_joint_trajectory_supervised(trajectory, velocity_scaling, collision_check)

Creates a instance of SteppedMotionClient for supervised trajectory execution :type trajectory: JointTrajectory :param trajectory: Joint trajectory which should be executed :type trajectory: JointTrajectory :type velocity_scaling: float :param velocity_scaling: scaling of velocity range 0.0 to 1.0 :type velocity_scaling: float :type collision_check: bool :param collision_check: If True check for collision while executing :type collision_check: bool convertable

Returns

result – Result of the trajectory execution

Return type

int

Raises

TypeError – If trajectory is not of type JointTrajectory or if collision_check is not convertable to bool

classmethod get_current_joint_values(joint_set)

Query the current joint positions of all joints in joint_set

Parameters

joint_set (JointSet) – Defines for which joint the positions are requested

Returns

positions – Returns a instance of JointValues with the positions of the requested joint set

Return type

JointValues

Raises

TypeError – If joint_set is not of type JointSet

move_gripper(action_name, position, max_effort)

Moves a gripper via the general ros interface GripperCommandAction

Parameters

• action_name (str convertable) – Name of the action to control a specific gripper

• position (float convertable) – Requested position of the gripper in meter

• max_effort (float convertable) – Force which should be applied

• Results –

• ------- –

• action_response (MoveGripperResult) – Result of the action execution

Raises

• TypeError – If inputs are not convertable to specified types

• ServiceException – If action server is not available

• RuntimeError – If action returns unexpected result

plan_cartesian_path(path, parameters)

Plan a joint trajectory from a cartesian path and plan parameters

Parameters

• path (CartesianPath) – Poses the planned trajectory must reach

• parameters (PlanParameters) – Plan parameters which defines the limits, settings and move group name

Returns

A joint trajectory which reach defined poses of path under the constrains in parameters

Return type

JointTrajectory

Raises

• TypeError – If path is not of type CartesianPath or parameters is not of type PlanParameters

• ValueError – If parameters joint set is not equal or sub set of the seed joint set and therefore reordering was not possible

• ServiceException – If query services are not available or finish unsuccessfully or inverse kinematics ends with error

classmethod plan_collision_free_joint_path(path, parameters)

Plans a collision free joint path by query it

Parameters

• path (JointPath) – joint path which should be replanned to be collision free

• parameters (PlanParameters) – plan parameters which defines the limits and move group

Returns

the replanned collision free joint path

Return type

JointPath

Raises

• TypeError – If path is not of type JointPath or if parameters is not of type PlanParameters

• ValueError – If parameters joint set is not equal or sub set of the path joint set and therefore reordering was not possible

• ServiceException – If query service is not available or finish unsuccessfully

classmethod plan_move_joints(path, parameters)

Plans trajectory from a joint path

Parameters

• path (JointPath) – joint path with positions the trajectory must reach

• parameters (PlanParameters) – plan parameters which defines the limits, settings and move group name

Returns

Planned joint trajectory which reach the positions defined in path under the constraints of parameters

Return type

JointTrajectory

Raises

• TypeError – If path is not of type JointPath or if parameters is not of type PlanParameters or

• ValueError – If parameters joint set is not equal or sub set of the path joint set and therefore reordering was not possible

• ServiceException – If query service is not available or finish unsuccessfully

classmethod plan_move_pose_linear(path, seed, parameters)

Plans trajectory with linear movements from a cartesian path

Parameters

• path (CartesianPath) – cartesian path with poses the trajectory must reach

• seed (JointValues) – numerical seed to control configuration

• parameters (TaskSpacePlanParameters) – plan parameters which defines the limits, settings and end effector name

Returns

Planned joint trajectory which reach the poses defined in path under the constraints of parameters

Return type

JointTrajectory

Raises

• TypeError – If path is not of type CartesianPath or if parameters is not of type TaskSpacePlanParameters or if seed is not of type JointValues

• ServiceException – If query service is not available or finish unsuccessfully

classmethod query_available_end_effectors()

Query all currently available end effectors

To query the available end effectors the ros service with the string defined in _query_move_group_service is called an only the relevant information about the endeffector is filtered out

Returns

end_effectors – Returns a dictionary key is the endeffector name, value is an instance of EndEffectorDescription

Return type

Dict[str, EndEffectorDescription]

Raises

• xamla_motion.ServiceExeption – If Service not exist or is not callable

• TypeError – If the service response joint_names are not of an iterable type

classmethod query_available_move_groups()

Query all currently available move groups

To query the move groups the ros service with the string defined in query_move_group_service is called

Returns

groups – Returns a list with instances of MoveGroupDescription. For further details please take a look into the documentation of MoveGroupDescription

Return type

List[MoveGroupDescription]

Raises

• xamla_motion.ServiceNotAvailableException – If Service not exist or is not callable

• TypeError – If the service response joint_names are not of an iterable type

classmethod query_collision_free_joint_path(move_group_name, joint_path)

Query a collision free joint path from a user defined joint path

Parameters

• move_group_name (str convertable) – name of the move group for which the collision free joint is required

• joint_path (JointPath) – joint path which may contains collisions

• Results –

• ------- –

• JointPath – New planned JointPath without collisions

:raises TypeError : type mismatch: If joint_path is not of expectef type JointPath or it move_group_name is not convertable to str :raises ServiceException: If query joint path service is not callable or is not successful

classmethod query_endeffector_limits(name)

Query end effector limits from ros param

To query the end effector limits the ros param definied in end_effector_limits_param is read out

Parameters

name (str convertable) – Name of the end effector for which the limits are queried

Returns

Returns a instance of EndEffectorLimits

Return type

EndEffectorLimits

Raises

• RuntimeError – If the the ros parameter or the requested end effector name no exists

• KeyError – If not all necessary limits exists

query_inverse_kinematics(pose, parameters, seed=[], end_effector_link='', timeout=None, attempts=1, const_seed=False)

Query inverse kinematic solutions one pose

Parameters

• pose (pose) – Pose to transform to joint space

• parameters (PlanParameters) – Plan parameters which defines the limits, settings and move group name

• seed (JointValues (optional)) – Numerical seed to control joint configuration

• end_effector_link (str convertable (optinal)) – necessary if poses are defined for end effector link

• timeout (datatime.timedelta (optional)) – timeout

• attempts (int convertable (optional default 1)) – Attempts to find a solution or each pose

• const_seed (bool convertable (optional default False)) – use constant seed instead of consecutive seeds

Returns

Instance of JointValues which is the joint space equivalent of the task space pose

Return type

JointValues

Raises

• TypeError – If pose is not of type Pose or parameters is not of type PlanParameters or seed is not empty list or type JointValues or the other parameters are not convertable to defined types

• ValueError – If parameters joint set is not equal or sub set of the seed joint set if defined and therefore reordering was not possible

• ServiceException – If query service is not available

query_inverse_kinematics_many(poses, parameters, seed=[], timeout=None, attempts=1, const_seed=False)

Query inverse kinematic solutions for a Iterable of Poses

Parameters

• poses (Iterable[EndEffectorPose]) – Iterable with EndEffectorPoses to transform to joint space

• parameters (PlanParameters) – Plan parameters which defines the limits, settings and move group name

• seed (JointValues (optional)) – Numerical seed to control joint configuration

• timeout (datatime.timedelta) – timeout

• attempts (int convertable (optional default 1)) – attempts to find a solution for each pose

• const_seed (bool convertable (optional default False)) – use constant seed instead of consecutive seeds

Returns

Instance of IkResult with all found solutions as a JointPath and error codes

Return type

IkResult

Raises

• TypeError – If poses is not of type EndEffectorPose or parameters is not of type PlanParameters or seed is not empty list or type JointValues or the other parameters are not convertable to defined types

• ValueError – If parameters joint set is not equal or sub set of the seed joint set if defined and therefore reordering was not possible

• ServiceException – If query service is not available

classmethod query_joint_limits(joint_set)

Query end joint limits from ros param

To query the joint limits the ros param definied in joint_limits_param + joint name + limit name is read out

Parameters

join_set (JointSet) – Set of joints for which the limits are queried

Returns

Returns a instance of JointLimits invalid limits are of type numpy.nan

Return type

JointLimits

:raises TypeError : type mismatch: If joint_set is not of expected type JointSet :raises KeyError: If ros params not exists

classmethod query_joint_path_collisions(move_group_name, joint_path)

Query collisions in joint path

Parameters

• move_group_name (str convertable) – Name of the move group for which a path should be check for collisions

• joint_path (JointPath) – The path that should be check for collisions

Returns

If collisions exists returns a list of JointValuesCollisions else returns None

Return type

List[JointValuesCollision] or None

Raises

TypeError – If move_group_name ist not str convertable or if joint_path is not of type JointPath

classmethod query_joint_states(joint_set)

Query joint states by calling the providing ros service

To query the joint states the ros service with the name defined in quary_joint_states_service is called

Parameters

joint_set (JointSet) – Set of joints for which the joint states are queried

Returns

Returns a instance of JointStates which contains the joint states of all joints defined in joint_set

Return type

JointStates

:raises TypeError : type mismatch: If joint_set is not of expected type JointSet :raises xamla_motion.ServiceException: If ros service not exists or is not callable

classmethod query_joint_trajectory(joint_path, max_velocity, max_acceleration, max_deviation, delta_t)

Query a joint trajectory from joint path / joint positions

Parameters

• joint_path (JointPath) – Defines the key joint positions the trajectory must reach

• max_velocity (Iterable[float convertable]) – Defines the maximal velocity for every joint

• max_acceleration (Iterable[float convertable]) – Defines the maximal acceleration for every joint

• max_deviation (float convertable) – Defines the maximal deviation of the joints to the defined key points while executing the trajectory

• delta_t (float convertable) – Sampling points frequency or time if value is create as 1.0 the value is interpreted as a value in seconds else the value is interpreted as a value in Hz

Returns

An instance of JointTrajectory with dense JointTrajectoryPoints

Return type

JointTrajectory

Raises

• TypeError – If joint_path is not of expected type JointPath or max_velocity or max_acceleration is not iterable or values of max_velocity, max_acceleration or delta_t are not convertable to float

• ValueError – If max_velocity or max_acceleration have not the same number of values has joints are defined in joint_path

classmethod query_pose(move_group_name, joint_positions, end_effector_link='')

Computes the pose by applying forward kinematics

Parameters

• move_group_name (str convertable) – name of the move group from which the pose is queried

• joint_positions (JointValues) – joint values from which the pose is calculated

• end_effector_link (str convertable (optional)) – end effector link is necessary if end effector is not part of the move group but pose should be computed for the end effector

Returns

Pose of the kinematic chain defined by the input parameter

Return type

Pose

Raises

TypeError – If joint_positions is not of type JointValues

classmethod query_pose_many(move_group_name, joint_path, end_effector_link='')

Query the poses from joint path points by applying forward kinematics

Parameters

• move_group_name (str convertable) – name of the move group from which the poses are queried

• joint_path (JointPath) – joint path from which the poses are calculated

• end_effector_link (str convertable (optional)) – end effector link is necessary if end effector is not part of the move group but pose should be computed for the end effector

Returns

List of Poses

Return type

List[Pose]

Raises

TypeError – If joint_path is not of type JointPath

classmethod query_task_space_trajectory(end_effector_name, cartesian_path, seed, max_xyz_velocity, max_xyz_acceleration, max_angular_velocity, max_angular_acceleration, ik_jump_threshold, max_deviation, collision_check, delta_t)

Query a joint trajectory from task space poses

Parameters

• end_effector_name (str convertable) – Name of the end effector for a trajectory should be quried

• cartesian_path (CartesianPath) – Define the key poses the trajectory must reach

• seed (JointValues) – numerical seed to control configuration of the robot

• max_xyz_velocity (float convertable) – max velocity for translation in m/s

• max_xyz_acceleration (float convertable) – max acceleration for translation in m/s^2

• max_angular_velocity (float convertable) – max angular velocity in rad/s

• max_angular_acceleration (float convertable) – max angular acceleration in rad/s^2

• ik_jump_threshold (float convertable) – maximal inverse kinematic jump

• max_deviation (float convertable) – Defines the maximal deviation of the joints to the defined key points while executing the trajectory

• collision_check (bool convertable) – If true check the trajectory is collision free

• delta_t (float convertable) – Sampling points frequency or time if value is create as 1.0 the value is interpreted as a value in seconds else the value is interpreted as a value in Hz

Returns

An instance of JointTrajectory with dense JointTrajectoryPoints

Return type

JointTrajectory

Raises

• TypeError – If cartesian_path is not of expected type CartesianPath or if seed is not of expected type JointValues max_* is not iterable or the values are not convertable as expected

• ValueError – If max_velocity or max_acceleration have not the same number of values has joints are defined in joint_path

wsg_gripper_command(action_name, command, width, speed, max_effort, stop_on_block=True)

Controls a WeissWsg gripper via the the specific action WsgCommandAction

Parameters

• action_name (str convertable) – Name of the action to control a specific gripper

• command (WsgCommand) – Specifies which kind of action should be performed

• width (float convertable) – Requested position of the gripper in meter

• speed (float convetable) – Requested speed in m/s

• max_effort (float convertable) – Force which should be applied

• Results –

• ------- –

• action_response (MoveGripperResult) – Result of the action execution

Raises

• TypeError – If inputs are not convertable to specified types or if command is no of type WsgCommand

• ServiceException – If action server is not available

• RuntimeError – If action returns unexpected result