message: Define finger_joint2 as mimic joint of finger_joint1
  Although, Gazebo doesn't support mimic joints natively,
  FrankaHWSim does and MoveIt - for planning - should know
  that the fingers will move in sync.
diff: <axis xyz="0 -1 0"/>
  <limit effort="20" lower="0.0" upper="0.04" velocity="0.2"/>
  <dynamics friction="0.0" damping="0.03"/>
  + <mimic joint="${ns}_finger_joint1" />
  </joint>
  </xacro:macro>
  </robot>
  