<?xml version="1.0" ?>
<sdf version="1.8">
  <world name="nested_model_world">
    <model name="parent_model">
      <link name="link1">
        <collision name="collision">
          <geometry>
            <box>
              <size>1 2 3</size>
            </box>
          </geometry>
        </collision>
        <visual name="visual">
          <geometry>
            <box>
              <size>1 2 3</size>
            </box>
          </geometry>
        </visual>
      </link>
      <joint name="joint1" type="revolute">
        <parent>world</parent>
        <child>link1</child>
        <axis>
          <xyz expressed_in="link1">1 0 0</xyz>
        </axis>
      </joint>
      <model name="nested_model">
        <pose>1 2 2  0 0 0</pose>
        <link name="nested_link1">
          <pose>3 1 1  0 0 1.5707</pose>
          <collision name="nested_collision1">
            <geometry>
              <sphere>
                <radius>2</radius>
              </sphere>
            </geometry>
          </collision>
        </link>
        <link name="nested_link2">
          <pose relative_to="nested_link1">0 1 0  1.5707 0 0</pose>
          <collision name="nested_collision2">
            <geometry>
              <sphere>
                <radius>2</radius>
              </sphere>
            </geometry>
          </collision>
        </link>
        <joint name="nested_joint1" type="revolute">
          <parent>world</parent>
          <child>nested_link1</child>
          <axis>
            <xyz expressed_in="nested_link1">1 0 0</xyz>
          </axis>
        </joint>
        <joint name="nested_joint2" type="revolute">
          <parent>nested_link1</parent>
          <child>nested_link2</child>
          <axis>
            <xyz expressed_in="nested_link2">1 0 0</xyz>
          </axis>
        </joint>
      </model>
    </model>
  </world>
</sdf>
