Gripper actuator

Actuator capable of grabbing objects marked with the Graspable Game Property. Currently it only works using services: grab and release. When instructed to grab an object, it will check if it is within range, and if so, will parent the grabbed object to itself.

Note

For objects to be detected and grabbed by the gripper, they must have the following settings in the Physics Properties panel:

  • Actor must be checked
  • Collision Bounds must be checked
  • Physics Type must be Rigid Body

This will work even for Static objects

This actuator is normally used together with robotic arms, such as the kuka actuator. To install the gripper on a robotic arm using the Morse Builder API, it is necessary to make the gripper a child of the arm, and to place the gripper in the correct position with respect to the arm. Example:

kuka_arm = Actuator('kuka_lwr')
kuka_arm.translate(x=0.1850, y=0.2000, z=0.9070)
kuka_arm.rotate(x=1.5708, y=1.5708)
Jido.append(kuka_arm)

gripper = Actuator('gripper')
gripper.translate(z=1.2800)
kuka_arm.append(gripper)

Warning

This actuator does not simulate the physical interaction of the gripper fingers with the objects it grabs. Its purpose is to abstract the action of taking an object, for human-robot interaction experiments.

Files

  • Blender: $MORSE_ROOT/data/actuators/gripper.blend
  • Python: $MORSE_ROOT/src/morse/actuators/gripper.py

Local data

  • grab: (boolean) Currently not used

Configurable parameters

The following parameters can be adjusted within the Logic Bricks of the Gripper object in Blender, in the properties of the Radar sensor.

  • Angle: (float) aperture angle of the radar capable of detecting the graspable objects.
  • Distance: (float) detection distance of the radar. Graspable objects further away from the gripper than this distance can not be held

Services

  • grab: (Synchronous service) Make the nearby object a child of the gripper, so that it will move around with the robot.
  • release: (Synchronous service) Drop the object being held. When the object is released, its rotation will be restored to zero (this helps to avoid objects falling and rolling around, but only when the object is dropped on a surface near below)

Applicable modifiers

No applicable modifiers

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