pycram.external_interfaces.ik

Module Contents

Functions

_make_request_msg(→ moveit_msgs.msg.PositionIKRequest)

Generates an ik request message for the kdl_ik_service. The message is

call_ik(→ typing_extensions.List[float])

Sends a request to the kdl_ik_service and returns the solution.

try_to_reach_with_grasp(...)

Checks if the robot can reach a given position with a specific grasp orientation.

apply_grasp_orientation_to_pose(...)

Applies the orientation of a grasp to a given pose. This is done by using the grasp orientation

try_to_reach(...)

request_ik(→ typing_extensions.List[float])

Top-level method to request ik solution for a given pose. Before calling the ik service the links directly before
pycram.external_interfaces.ik._make_request_msg(root_link: str, tip_link: str, target_pose: pycram.datastructures.pose.Pose, robot_object: pycram.world_concepts.world_object.Object, joints: typing_extensions.List[str]) → moveit_msgs.msg.PositionIKRequest

Generates an ik request message for the kdl_ik_service. The message is of the type moveit_msgs/PositionIKRequest and contains all information contained in the parameter.

Parameters:

  • root_link – The first link of the chain of joints to be altered

  • tip_link – The last link of the chain of joints to be altered

  • target_pose – Target pose for which the message should be created

  • robot_object – The robot for which the ik should be generated

  • joints – A list of joint names between the root_link and tip_link that should be altered.

Returns:

A moveit_msgs/PositionIKRequest message containing all the information from the parameter

pycram.external_interfaces.ik.call_ik(root_link: str, tip_link: str, target_pose: pycram.datastructures.pose.Pose, robot_object: pycram.world_concepts.world_object.Object, joints: typing_extensions.List[str]) → typing_extensions.List[float]

Sends a request to the kdl_ik_service and returns the solution. Note that the robot in robot_object should be identical to the robot description uploaded to the parameter server. Furthermore, note that the root_link and tip_link are the links attached to the first and last joints in the joints list.

Parameters:

  • root_link – The first link of the chain of joints to be altered

  • tip_link – The last link in the chain of joints to be altered

  • target_pose – The target pose in frame of root link second is the orientation as quaternion in world coordinate frame

  • robot_object – The robot object for which the ik solution should be generated

  • joints – A list of joint name that should be altered

Returns:

The solution that was generated as a list of joint values corresponding to the order of joints given

pycram.external_interfaces.ik.try_to_reach_with_grasp(pose_or_object: typing_extensions.Union[pycram.datastructures.pose.Pose, pycram.world_concepts.world_object.Object], prospection_robot: pycram.world_concepts.world_object.Object, gripper_name: str, grasp: str) → typing_extensions.Union[pycram.datastructures.pose.Pose, None]

Checks if the robot can reach a given position with a specific grasp orientation. To determine this the inverse kinematics are calculated and applied.

Parameters:

  • pose_or_object – The position and rotation or Object for which reachability should be checked or an Object

  • prospection_robot – The robot that should reach for the position

  • gripper_name – The name of the end effector

  • grasp – The grasp type with which the object should be grasped

pycram.external_interfaces.ik.apply_grasp_orientation_to_pose(grasp: str, pose: pycram.datastructures.pose.Pose) → pycram.datastructures.pose.Pose

Applies the orientation of a grasp to a given pose. This is done by using the grasp orientation of the given grasp and applying it to the given pose.

Parameters:

  • grasp – The name of the grasp

  • pose – The pose to which the grasp orientation should be applied

pycram.external_interfaces.ik.try_to_reach(pose_or_object: typing_extensions.Union[pycram.datastructures.pose.Pose, pycram.world_concepts.world_object.Object], prospection_robot: pycram.world_concepts.world_object.Object, gripper_name: str) → typing_extensions.Union[pycram.datastructures.pose.Pose, None]
pycram.external_interfaces.ik.request_ik(target_pose: pycram.datastructures.pose.Pose, robot: pycram.world_concepts.world_object.Object, joints: typing_extensions.List[str], gripper: str) → typing_extensions.List[float]

Top-level method to request ik solution for a given pose. Before calling the ik service the links directly before and after the joint chain will be queried and the target_pose will be transformed into the frame of the root_link. Afterward, the offset between the tip_link and end effector will be calculated and taken into account. Lastly the ik service is called and the result returned

Parameters:

  • target_pose – Pose for which an ik solution should be found

  • robot – Robot object which should be used

  • joints – List of joints that should be used in computation

  • gripper – Name of the gripper which should grasp, this should be at the end of the given joint chain

Returns:

A list of joint values