KUKA LWR arm actuator

This actuator reads a list of angles for the segments of the LWR arm and applies them as local rotations. It is a subclass of the armature_actuator. Angles are expected in radians.

To install additional components at the tip of the arm using the MORSE Builder API, it is necessary to make the additional component as a child of the arm, and to place the component in the correct position with respect to the kuka arm. Example:

kuka_arm = KukaLWR()
kuka_arm.translate(x=0.1850, y=0.2000, z=0.9070)
kuka_arm.rotate(x=1.5708, y=1.5708)

gripper = Gripper()

When the simulation is started any objects that are children of the KUKA arm will automatically be changed to be children of the last segment of the arm.



  • Blender: $MORSE_ROOT/data/robots/kuka_lwr.blend

    Unlike other actuators, this one also includes the mesh of the arm (composed of 8 segments) and an armature that controls its movement.

  • Python: $MORSE_ROOT/src/morse/actuators/kuka_lwr.py

Local data


There are 7 floating point values, named after the bones in the armature:

  • kuka_1: (float) rotation for the first segment. Around Z axis.
  • kuka_2: (float) rotation for the second segment. Around Y axis.
  • kuka_3: (float) rotation for the third segment. Around Z axis.
  • kuka_4: (float) rotation for the fourth segment. Around Y axis.
  • kuka_5: (float) rotation for the fifth segment. Around Z axis.
  • kuka_6: (float) rotation for the sixth segment. Around Y axis.
  • kuka_7: (float) rotation for the seventh segment. Around Z axis.

These names are generated dynamically, so that if there are more than one arm in the scene, there will not be any conflicts.

Configurable parameters

No configurable parameters

Applicable modifiers

No available modifiers

Available services

See the documentation for the armature_actuator. There is also an additional service specific to this armature:

  • set_rotation_array: (service) Receives an array indicating the angle to give to each of the segments of the arm. Angles are expected in radians. The length of the array should be equal to 7 or less, where any values not specified will be considered as 0.0. If parameters exceeds IK limits, the whole request is rejected.



    Array of floats

    Parameters: (rotation_array)

  • set_rotation: (service) Makes the indicated segment rotate by the indicated angle. Receives the name of the segment to rotate, and the amount in radians. If rotations exceeds IK limits, the request is rejected.



    Name of the armature bone to rotate (see the list above)



    Array of 3 floats, with the angles to rotate around X, Y, Z. Note that given the restrictions imposed on the armature, only one of the rotation angles will be used.

    Parameters: (channel_name, rotation)


A note for developpers: The orientation of the bones in the ‘kuka_armature’ in the Blender file will determine the direction of the rotations. To be consistent with the joint rotations of the real arm, the bones must have the following roll value (in the Bone panel when in Edit Mode):

  • kuka_1: 180
  • kuka_2: 0
  • kuka_3: 0
  • kuka_4: 180
  • kuka_5: 180
  • kuka_6: 0
  • kuka_7: 180

This is valid for Blender version 2.59

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