built in control on a urdf model in gazebo

edit

Hi. i built a urdf model of an inverted pendlum and spawned it in gazebo. it looks as if there is buil in control on it like if it falls it will stand right up. how can i stop that control?

<?xml version="1.0" ?>
<robot name="pendelum"> 

  <link name="rod">
   <inertial>
     <mass value="0.001"/>
     <origin xyz="0 0 0" rpy="0 0 0"/>

     <inertia ixx="0.00"  ixy="0"  ixz="0" iyy="0.00" iyz="0"    izz="0.00" />
     </inertial>

   <physics type="ode" update_rate="100">
     <gravity xyz="0 0 -9.8"/>
         <ode>
           <solver type="quick" dt="0.01" iters="100" sor="1.3"/>
          </ode>
    </physics>

   <visual>
     <origin xyz="0 0 0.5" rpy="0 0 0" />
     <geometry>
      <cylinder radius="0.02" length="1"/>
     </geometry>
   </visual>

 <collision>
     <origin xyz="0 0 0.5" rpy="0 0 0"/>
     <geometry>
       <cylinder radius="0.02" length="1"/>
     </geometry>
   </collision>

 </link>

  <link name="cmass"> 
    <inertial>
      <mass value="10.0" />
      <origin xyz="0 0 0" /> 
      <inertia  ixx="0.1" ixy="0.0"  ixz="0.0"  iyy="10"  iyz="0.0"  izz="0.1" />
    </inertial>

    <visual>
      <origin xyz="0 0 1" rpy="0 0 0" />
      <geometry>
        <sphere radius="0.05"/>
      </geometry>
    </visual>

    <collision>
      <origin xyz="0 0 1" rpy="0 0 0" />
      <geometry>
        <sphere radius="0.05"/>
      </geometry>
    </collision>


  </link>

   <joint name="weld" type="fixed">
    <parent link="rod" />
    <child link="cmass" />

  </joint>

   <link name="wor"> 
    <inertial>
      <mass value="100000" />
      <!-- center of mass (com) is defined w.r.t. link local   coordinate system -->
      <origin xyz="0 0 0" /> 
      <inertia  ixx="1000.0" ixy="0.0"  ixz="0.0"  iyy="1000.0"  iyz="0.0"  izz="1000.0" />
    </inertial>

    <visual>
      <origin xyz="0 0 0.0005" rpy="0 0 0" />
      <geometry>
        <box size="0.4 0.4 0.001"/>
      </geometry>
    </visual>


<collision>
      <origin xyz="0 0 0.0005" rpy="0 0 0" />
      <geometry>
        <box size="0.4 0.4 0.001"/>
      </geometry>
    </collision>
  </link>

<joint name="floor" type="revolute">
   <parent link="wor" />
    <child link="rod" />
    <origin xyz="0 0 0" rpy="0 0 0" />
    <axis xyz="0 1 0"/>
<limit upper="3.15" lower="-3.15" effort="1000.00" velocity="1000.00"/>
<joint_properties damping="0.1" friction="1.0" />
</joint>

 <gazebo>
    <controller:gazebo_ros_controller_manager name="gazebo_ros_controller_manager" plugin="libgazebo_ros_controller_manager.so">
      <alwaysOn>true</alwaysOn>
      <updateRate>1000.0</updateRate>
      <interface:audio name="gazebo_ros_controller_manager_dummy_iface" />
    </controller:gazebo_ros_controller_manager>
  </gazebo>

<gazebo reference="cmass">
    <turnGravityOff>false</turnGravityOff>
    <material>Gazebo/Blue</material>
  </gazebo>

  <gazebo reference="rod">
    <turnGravityOff>false</turnGravityOff>
    <material>Gazebo/Red</material>
  </gazebo>

  <gazebo reference="wor">
    <turnGravityOff>true</turnGravityOff>
    <material>Gazebo/Red</material>
  </gazebo>

   </robot>

any ideas? Thanks Nachum