example_1.urdf

<?xml version="1.0"?>
<robot name="example">
  <link name="link1">
    <inertial>
      <mass value="1"/>
      <inertia ixx="1" iyy="1" izz="1" ixy="0" ixz="0" iyz="0"/>
    </inertial>
  </link>
  <link name="link2">
    <inertial>
      <mass value="1"/>
      <inertia ixx="1" iyy="1" izz="1" ixy="0" ixz="0" iyz="0"/>
    </inertial>
  </link>
  <joint name="test_joint_1" type="continuous">
    <parent link="link1"/>
    <child link="link2"/>
    <limit velocity="10.0" effort="10.0"/>
  </joint>
  <transmission name="test_joint_trans">
    <type>transmission_interface/SimpleTransmission</type>
    <joint name="test_joint_1">
      <hardwareInterface>hardware_interface/PositionJointInterface</hardwareInterface>
      <hardwareInterface>hardware_interface/VelocityJointInterface</hardwareInterface>
      <hardwareInterface>hardware_interface/EffortJointInterface</hardwareInterface>
    </joint>
    <actuator name="test_joint_motor_1">
      <mechanicalReduction>66</mechanicalReduction>
    </actuator>
  </transmission>
</robot>