robot.urdf

<robot name="robot_model">

  <link name="base_frame">
    <visual>
      <geometry>
        <box size="0.16 0.16 0.07"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0.085"/>
      <material name="white">
        <color rgba="1 1 1 1"/>
      </material>
    </visual>
    <collision>
      <geometry>
        <box size="0.20 0.20 0.07"/>
      </geometry>
    </collision>
  </link>

  <link name="lwheel">
    <visual>
      <geometry>
        <cylinder length="0.02" radius="0.04"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

 <joint name="base_to_lwheel" type="fixed">
    <parent link="base_frame"/>
    <child link="lwheel"/>
    <origin xyz="0 0.085 0.07" rpy="1.5708 0 0"/>
  </joint>

  <link name="rwheel">
    <visual>
      <geometry>
        <cylinder length="0.02" radius="0.04"/>
      </geometry>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <material name="black">
        <color rgba="0 0 0 1"/>
      </material>
    </visual>
  </link>

 <joint name="base_to_rwheel" type="fixed">
    <parent link="base_frame"/>
    <child link="rwheel"/>
    <origin xyz="0 -0.085 0.07" rpy="-1.5708 0 0"/>
  </joint>

  <link name="laser">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
     <cylinder length="0.01" radius="0.03"/>
      </geometry>
    </visual>
  </link>

<joint name="laser_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.0 0.0 0.125"/>
    <parent link="base_frame"/>
    <child link="laser"/>
  </joint>

  <link name="ultrasonic">
    <visual>
      <origin rpy="0 0 0" xyz="0 0 0"/>
      <geometry>
     <box size="0.02 0.02 0.02"/>
      </geometry>
        <material name="red">
        <color rgba="1 0 0 0"/>
      </material>
    </visual>
  </link>

<joint name="ultrasonic_joint" type="fixed">
    <origin rpy="0 0 0" xyz="0.09 0.0 0.13"/>
    <parent link="base_frame"/>
    <child link="ultrasonic"/>
  </joint>

</robot>