message: changes link 7 collision volume to an equivalent description.
diff: </joint>
  <link name="${arm_id}_link8">
  <collision>
  - <origin xyz="0.0424 0.0424 -0.0250" rpy="${-pi/4} ${pi/2} 0"/>
  + <origin xyz="0.0424 0.0424 -0.0250" rpy="${pi} ${pi/2} ${pi/2}"/>
  <geometry>
  <cylinder radius="0.03" length="0.01" />
  </geometry>
  