<?xml version="1.0" ?>
<sdf version='1.6'>
  <world name="default">
    <gravity>0 -10 0</gravity>
    <physics type="dart">
      <dart>
        <solver>
          <solver_type>pgs</solver_type>
        </solver>
      </dart>
    </physics>

    <include>
      <uri>model://ground_plane</uri>
    </include>

    <include>
      <uri>model://sun</uri>
    </include>

    <model name="anchored_loop">
      <link name="link1">
        <pose>0 0 0.2 0.6435 0 0</pose>
        <collision name="collision">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </collision>
        <visual name="visual">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </visual>
      </link>

      <link name="link2">
        <pose>0.1 -0.3 0.6 1.5708 0 0</pose>
        <collision name="collision">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </collision>
        <visual name="visual">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </visual>
      </link>

      <link name="link3">
        <pose>0 -0.8 0.6 2.4981 0 0</pose>
        <collision name="collision">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </collision>
        <visual name="visual">
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <box>
              <size>0.1 0.2 0.7</size>
            </box>
          </geometry>
        </visual>
      </link>

      <joint name="joint1" type="revolute">
        <parent>world</parent>
        <child>link1</child>
        <axis>
          <xyz>1 0 0</xyz>
        </axis>
      </joint>

      <joint name="joint2" type="revolute">
        <parent>link1</parent>
        <child>link2</child>
        <axis>
          <xyz>1 0 0</xyz>
        </axis>
      </joint>

      <joint name="joint3" type="revolute">
        <parent>link2</parent>
        <child>link3</child>
        <axis>
          <xyz>1 0 0</xyz>
          <dynamics>
            <damping>5</damping>
            <friction>0.1</friction>
          </dynamics>
        </axis>
      </joint>

      <joint name="joint4" type="revolute">
        <pose>0 0 0.5 0 0 0</pose>
        <parent>world</parent>
        <child>link3</child>
        <axis>
          <xyz>1 0 0</xyz>
        </axis>
      </joint>
    </model>

  </world>
</sdf>
