XML Element[sensor], child of element[model] not defined in SDF. Ignoring[sensor].

edit

Hi, I am trying to publish laser data on a topic from gazebo so that I can visualize in RVIZ. Following is the sdf code. Can anyone let me know what I am doing wrong? Thanks in advance

 <?xml version='1.0'?>
<sdf version='1.4'>
  <model name="my_robot">
    <static>true</static>
    <link name='chassis'>
      <pose>0 0 .1 0 0 0</pose>
      <collision name='collision'>
        <geometry>
          <box>
            <size>.4 .2 .1</size>
          </box>
        </geometry>
      </collision>

      <visual name='visual'>
        <geometry>
          <box>
            <size>.4 .2 .1</size>
          </box>
        </geometry>
      </visual>
       <collision name='caster_collision'>
        <pose>-0.15 0 -0.05 0 0 0</pose>
        <geometry>
            <sphere>
            <radius>.05</radius>
          </sphere>
        </geometry>

        <surface>
          <friction>
            <ode>
              <mu>0</mu>
              <mu2>0</mu2>
              <slip1>1.0</slip1>
              <slip2>1.0</slip2>
            </ode>
          </friction>
        </surface>
      </collision>

      <visual name='caster_visual'>
        <pose>-0.15 0 -0.05 0 0 0</pose>
        <geometry>
          <sphere>
            <radius>.05</radius>
          </sphere>
        </geometry>
      </visual>
    </link>
   <include>
  <uri>model://hokuyo</uri>
  <pose>0.2 0 0.2 0 0 0</pose>
</include>
<joint name="hokuyo_joint" type="fixed">
  <child>hokuyo::link</child>
  <parent>chassis</parent>
</joint>

<sensor name="head_hokuyo_sensor">
  <pose>0 0 0 0 0 0</pose>
  <visualize>false</visualize>
  <update_rate>40</update_rate>
  <ray>
    <scan>
      <horizontal>
        <samples>720</samples>
        <resolution>1</resolution>
        <min_angle>-1.570796</min_angle>
        <max_angle>1.570796</max_angle>
      </horizontal>
    </scan>
    <range>
      <min>0.10</min>
      <max>30.0</max>
      <resolution>0.01</resolution>
    </range>
    <noise>
      <type>gaussian</type>
      <!-- Noise parameters based on published spec for Hokuyo laser
           achieving "+-30mm" accuracy at range < 10m.  A mean of 0.0m and
           stddev of 0.01m will put 99.7% of samples within 0.03m of the true
           reading. -->
      <mean>0.0</mean>
      <stddev>0.01</stddev>
    </noise>
  </ray>
  <plugin name="gazebo_ros_head_hokuyo_controller" filename="libgazebo_ros_gpu_laser.so">
    <topicName>/rrbot/laser/scan</topicName>
  </plugin>
</sensor>
  </model>
</sdf>