<?xml version="1.0" ?>

<sdf version="1.6">
  <world name="triball_drift">
    <gravity>1 0 -9.8</gravity>
    <plugin
      filename="libignition-gazebo-physics-system.so"
      name="ignition::gazebo::systems::Physics">
    </plugin>
    <plugin
      filename="libignition-gazebo-user-commands-system.so"
      name="ignition::gazebo::systems::UserCommands">
    </plugin>
    <plugin
      filename="libignition-gazebo-scene-broadcaster-system.so"
      name="ignition::gazebo::systems::SceneBroadcaster">
    </plugin>


    <gui fullscreen="0">

      <!-- 3D scene -->
      <plugin filename="GzScene3D" name="3D View">
        <ignition-gui>
          <title>3D View</title>
          <property type="bool" key="showTitleBar">false</property>
          <property type="string" key="state">docked</property>
        </ignition-gui>

        <engine>ogre2</engine>
        <scene>scene</scene>
        <ambient_light>0.4 0.4 0.4</ambient_light>
        <background_color>0.8 0.8 0.8</background_color>
        <camera_pose>-6 0 6 0 0.5 0</camera_pose>
      </plugin>

      <!-- World control -->
      <plugin filename="WorldControl" name="World control">
        <ignition-gui>
          <title>World control</title>
          <property type="bool" key="showTitleBar">false</property>
          <property type="bool" key="resizable">false</property>
          <property type="double" key="height">72</property>
          <property type="double" key="width">121</property>
          <property type="double" key="z">1</property>

          <property type="string" key="state">floating</property>
          <anchors target="3D View">
            <line own="left" target="left"/>
            <line own="bottom" target="bottom"/>
          </anchors>
        </ignition-gui>

        <play_pause>true</play_pause>
        <step>true</step>
        <start_paused>true</start_paused>
        <service>/world/triball_drift/control</service>
        <stats_topic>/world/triball_drift/stats</stats_topic>

      </plugin>

      <!-- World statistics -->
      <plugin filename="WorldStats" name="World stats">
        <ignition-gui>
          <title>World stats</title>
          <property type="bool" key="showTitleBar">false</property>
          <property type="bool" key="resizable">false</property>
          <property type="double" key="height">110</property>
          <property type="double" key="width">290</property>
          <property type="double" key="z">1</property>

          <property type="string" key="state">floating</property>
          <anchors target="3D View">
            <line own="right" target="right"/>
            <line own="bottom" target="bottom"/>
          </anchors>
        </ignition-gui>

        <sim_time>true</sim_time>
        <real_time>true</real_time>
        <real_time_factor>true</real_time_factor>
        <iterations>true</iterations>
        <topic>/world/triball_drift/stats</topic>

      </plugin>

    </gui>
    <model name="ground_plane">
      <static>true</static>
      <link name="link">
        <collision name="collision">
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
        </collision>
        <visual name="visual">
          <geometry>
            <plane>
              <normal>0 0 1</normal>
              <size>100 100</size>
            </plane>
          </geometry>
          <material>
            <ambient>0.8 0.8 0.8 1</ambient>
            <diffuse>0.8 0.8 0.8 1</diffuse>
            <specular>0.8 0.8 0.8 1</specular>
          </material>
        </visual>
      </link>
    </model>

    <light type="directional" name="sun">
      <cast_shadows>true</cast_shadows>
      <pose>0 0 10 0 0 0</pose>
      <diffuse>1 1 1 1</diffuse>
      <specular>0.5 0.5 0.5 1</specular>
      <attenuation>
        <range>1000</range>
        <constant>0.9</constant>
        <linear>0.01</linear>
        <quadratic>0.001</quadratic>
      </attenuation>
      <direction>-0.5 0.1 -0.9</direction>
    </light>

    <model name="triball_lumped">
      <pose>0 0 0  0 0 0</pose>
      <link name="link">
        <pose>0 0 0.25  0 0 0</pose>
        <inertial>
          <pose>0.0 0.0 0  0 0 0</pose>
          <mass>7.911</mass>
          <inertia>
            <ixx>2.9446500000000007</ixx>
            <iyy>2.944649999999999</iyy>
            <izz>5.691525</izz>
            <ixy>0.0</ixy>
            <ixz>0.0</ixz>
            <iyz>0.0</iyz>
          </inertia>
        </inertial>
        <sensor name="imu" type="imu">
          <always_on>1</always_on>
        </sensor>

        <collision name="collision_a">
          <pose>0.8333333333333333 0 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a">
          <pose>0.8333333333333333 0 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_b">
          <pose>-0.41666666666666663 0.7216878364870323 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_b">
          <pose>-0.41666666666666663 0.7216878364870323 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_c">
          <pose>-0.41666666666666663 -0.7216878364870323 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_c">
          <pose>-0.41666666666666663 -0.7216878364870323 0  0 0 0</pose>
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

      </link>
    </model>
    <model name="triball_fixed">
      <pose>0 3 0  0 0 0</pose>
      <link name="chassis">
        <pose>0 0 0.25  0 0 0</pose>
        <inertial>
          <pose>0.0 0.0 0 0 0 0</pose>
          <mass>3.9555</mass>
          <inertia>
            <ixx>1.4723250000000003</ixx>
            <iyy>1.4723249999999994</iyy>
            <izz>2.8457625</izz>
            <ixy>0.0</ixy>
            <ixz>0.0</ixz>
            <iyz>0.0</iyz>
          </inertia>
        </inertial>
        <sensor name="imu" type="imu">
          <always_on>1</always_on>
        </sensor>

        <collision name="collision_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>1.0 0.2 0.2 1</ambient>
            <diffuse>1.0 0.2 0.2 1</diffuse>
            <specular>1.0 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

      </link>

      <link name="link_a">
        <pose>0.8333333333333333 0 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_a" type="fixed">
        <parent>chassis</parent>
        <child>link_a</child>
      </joint>

      <link name="link_b">
        <pose>-0.41666666666666663 0.7216878364870323 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_b" type="fixed">
        <parent>chassis</parent>
        <child>link_b</child>
      </joint>

      <link name="link_c">
        <pose>-0.41666666666666663 -0.7216878364870323 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.9</mu>
                <mu2>0.9</mu2>
                <fdir1>1 0 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_c" type="fixed">
        <parent>chassis</parent>
        <child>link_c</child>
      </joint>

    </model>
    <model name="triball_revolute">
      <pose>0 6 0  0 0 0</pose>
      <link name="chassis">
        <pose>0 0 0.25  0 0 0</pose>
        <inertial>
          <pose>0.0 0.0 0 0 0 0</pose>
          <mass>3.9555</mass>
          <inertia>
            <ixx>1.4723250000000003</ixx>
            <iyy>1.4723249999999994</iyy>
            <izz>2.8457625</izz>
            <ixy>0.0</ixy>
            <ixz>0.0</ixz>
            <iyz>0.0</iyz>
          </inertia>
        </inertial>
        <sensor name="imu" type="imu">
          <always_on>1</always_on>
        </sensor>

        <collision name="collision_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_b">
          <pose>0.20833333333333331 0.36084391824351614 0.0  -1.5707962969925737 -1.0471975511965974 1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 1.0 0.2 1</ambient>
            <diffuse>0.2 1.0 0.2 1</diffuse>
            <specular>0.2 1.0 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_a_to_c">
          <pose>0.20833333333333331 -0.36084391824351614 0.0  1.5707962969925737 -1.0471975511965974 -1.047197525387029</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

        <collision name="collision_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <surface>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual_b_to_c">
          <pose>-0.41666666666666663 0.0 0.0  1.5707963267948963 -0.0 0.0</pose>
          <geometry>
            <cylinder>
              <radius>0.0625</radius>
              <length>1.4433756729740645</length>
            </cylinder>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>

      </link>

      <link name="link_a">
        <pose>0.8333333333333333 0 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
                <fdir1>0 1 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_a" type="revolute">
        <parent>chassis</parent>
        <child>link_a</child>
        <axis>
          <xyz>0 1 0</xyz>
          <dynamics>
            <friction>0.1</friction>
          </dynamics>
        </axis>
      </joint>

      <link name="link_b">
        <pose>-0.41666666666666663 0.7216878364870323 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
                <fdir1>0 1 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_b" type="revolute">
        <parent>chassis</parent>
        <child>link_b</child>
        <axis>
          <xyz>0 1 0</xyz>
          <dynamics>
            <friction>0.1</friction>
          </dynamics>
        </axis>
      </joint>

      <link name="link_c">
        <pose>-0.41666666666666663 -0.7216878364870323 0.25  0 0 0</pose>
        <inertial>
          <mass>1.3185</mass>
          <inertia>
            <ixx>0.0329625</ixx>
            <iyy>0.0329625</iyy>
            <izz>0.0329625</izz>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyz>0</iyz>
          </inertia>
        </inertial>
        <collision name="collision">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <surface>
            <contact>
              <ode>
                <kp>10000000.0</kp>
                <kd>1.0</kd>
              </ode>
            </contact>
            <friction>
              <ode>
                <mu>0.1</mu>
                <mu2>0.1</mu2>
                <fdir1>0 1 0</fdir1>
              </ode>
            </friction>
          </surface>
        </collision>
        <visual name="visual">
          <geometry>
            <sphere>
              <radius>0.25</radius>
            </sphere>
          </geometry>
          <material>
            <ambient>0.2 0.2 0.2 1</ambient>
            <diffuse>0.2 0.2 0.2 1</diffuse>
            <specular>0.2 0.2 0.2 1</specular>
          </material>
        </visual>
      </link>
      <joint name="joint_c" type="revolute">
        <parent>chassis</parent>
        <child>link_c</child>
        <axis>
          <xyz>0 1 0</xyz>
          <dynamics>
            <friction>0.1</friction>
          </dynamics>
        </axis>
      </joint>
      <plugin
        filename="libignition-gazebo-wheel-slip-system.so"
        name="ignition::gazebo::systems::WheelSlip">
        <wheel link_name="link_a">
          <wheel_radius>0.25</wheel_radius>
          <slip_compliance_lateral>1</slip_compliance_lateral>
          <slip_compliance_longitudinal>1</slip_compliance_longitudinal>
          <wheel_normal_force>25</wheel_normal_force>
        </wheel>
        <wheel link_name="link_b">
          <wheel_radius>0.25</wheel_radius>
          <slip_compliance_lateral>1</slip_compliance_lateral>
          <slip_compliance_longitudinal>1</slip_compliance_longitudinal>
          <wheel_normal_force>25</wheel_normal_force>
        </wheel>
        <wheel link_name="link_c">
          <wheel_radius>0.25</wheel_radius>
          <slip_compliance_lateral>1</slip_compliance_lateral>
          <slip_compliance_longitudinal>1</slip_compliance_longitudinal>
          <wheel_normal_force>25</wheel_normal_force>
        </wheel>
      </plugin>

    </model>
  </world>
</sdf>
