pi_robot.urdf

<robot name="pi_robot">
   <link name="map">
      <visual>
          <geometry>
              <box size="0.32 0.26 0.22" />
          </geometry>
          <material name="Cyan">
                 <color rgba="0 1 1  1.0"/>
           </material>
      </visual>
  </link>

  <joint name="torso_joint" type="revolute">
    <parent link="map" />
    <child link="torso_link" />
    <origin xyz="0 0 0.22" rpy="0 0 0" />
    <axis xyz="0 1 0" />
    <limit lower="-3.1416" upper="3.1416" effort="10" velocity="3" />
  </joint>
  
  <link name="torso_link">
      <visual>
          <geometry>
              <cylinder radius="0.07" length="0.24" />
          </geometry>
           <material name="Yellow">
              <color rgba="1 1 0 1.0"/>
          </material>
     </visual>
  </link>
  
  <joint name="neck_joint" type="revolute">
    <parent link="torso_link" />
    <child link="neck_link" />
    <origin xyz="0 0 0.24" rpy="0 0 0" />
    <axis xyz="0 1 0" />
    <limit lower="-1.57" upper="1.57" effort="1" velocity="3" />
  </joint>
 
  <link name="neck_link">
      <visual>
          <geometry>
              <box size="0.05 0.05 0.05" />
          </geometry>
           <material name="Green">
              <color rgba="0 1 0 1.0"/>
          </material>
     </visual>
  </link>

</robot>