Arm Commander¶

Overview¶

The SrArmCommander inherits all methods from the robot commander and provides commands specific to the arm. It allows movement to a certain position in cartesian space, to a configuration in joint space or move using certain trajectory.

Setup¶

Import the arm commander along with basic rospy libraries and the arm finder:

import rospy
from sr_robot_commander.sr_arm_commander import SrArmCommander
from sr_utilities.arm_finder import ArmFinder

The constructors for SrArmCommander take a name parameter that should match the group name of the robot to be used and has the option to add ground to the scene.

arm_commander = SrArmCommander(name="right_arm", set_ground=True)

Use the ArmFinder to get the parameters (such as prefix) and joint names of the arm currently running on the system:

arm_finder = ArmFinder()

# To get the prefix or mapping of the arm joints. Mapping is the same as prefix but without underscore.
arm_finder.get_arm_parameters().joint_prefix.values()
arm_finder.get_arm_parameters().mapping.values()

# To get the arm joints
arm_finder.get_arm_joints()

Getting information¶

To return the reference frame for planning in cartesian space:

reference_frame = arm_commander.get_pose_reference_frame()

Plan/move to a position target¶

Using the method move_to_position_target, the end effector of the arm can be moved to a certain point in space represented by (x, y, z) coordinates. The orientation of the end effector can take any value.

Parameters:

xyz desired position of end-effector
end_effector_link name of the end effector link (default value is empty string)
wait indicates if the method should wait for the movement to end or not (default value is True)

Example¶

rospy.init_node("robot_commander_examples", anonymous=True)
arm_commander = SrArmCommander(name="right_arm", set_ground=True)

new_position = [0.25527, 0.36682, 0.5426]

# To only plan
arm_commander.plan_to_position_target(new_position)

# To plan and move
arm_commander.move_to_position_target(new_position)

Plan/move to a pose target¶

Using the method move_to_pose_target allows the end effector of the arm to be moved to a certain pose (position and orientation) in the space represented by (x, y, z, rot_x, rot_y, rot_z).

Parameters:

pose desired pose of end-effector: a Pose message, a PoseStamped message or a list of 6 floats: [x, y, z, rot_x, rot_y, rot_z] or a list of 7 floats [x, y, z, qx, qy, qz, qw]
end_effector_link name of the end effector link (default value is empty string)
wait indicates if the method should wait for the movement to end or not (default value is True)

Example¶

rospy.init_node("robot_commander_examples", anonymous=True)
arm_commander = SrArmCommander(name="right_arm", set_ground=True)

new_pose = [0.5, 0.3, 1.2, 0, 1.57, 0]

# To only plan
arm_commander.plan_to_pose_target(new_pose)

# To plan and move
arm_commander.move_to_pose_target(new_pose)