1) [Turtlebot3 코드정리]gazebo를 통한 시뮬레이션 환경

*오픈소스인 turtlebot3의 코드를 정리하면서 각 파일들이 어떻게 동작하는 지 확인함.

로보티즈 e-manual에 나오는 순서대로 따라하면 

1) gazebo를 통한 시뮬레이션 환경

2) slam을 통한 지도 작성 ( option 자율이동 또는 수동이동 )

3) 작성된 지도를 바탕으로한 navigation 수행 

의 순서로 진행되며 처음 정리를 위하여 gazebo를 통해 해당 코드가 어떻게 수행되는 지 정리하였다.

 

 

turtlebot3 waffle 모델을 통해 turtlebot3_world를 실행시켯을 때 화면

1) 실행코드

-> 각각의 모델에 따라 export 시켜 준 뒤 roslaunch를 통해서 gazeobo를 통해 환경을 불러온다.

- simulation
export TURTLEBOT3_MODEL=waffle_pi
roslaunch turtlebot3_gazebo turtlebot3_house.launch

export TURTLEBOT3_MODEL=burger
roslaunch turtlebot3_gazebo turtlebot3_empty_world.launch

export TURTLEBOT3_MODEL=waffle
roslaunch turtlebot3_gazebo turtlebot3_world.launch

2) 실행 파일 확인

-> 위에서 실행시킬 때 roslaunch 뒤에 있는 turtlebot3_gazebo 가 roscd package의 이름이다. roscd 명령어를 통해 해당 패키지로 들어가보면 실제 실행시에 어떤 파일이 실행되는 지 확인가능하다. 폴더를 보고싶을 때는 linux에서 nautilus . 명령어를 통해 폴더구조를 확인해보자.

// roscd 패키지이름
roscd turtlebot3_gazebo

파일경로
home/사용자명/catkin_ws/src/turtlebot3_simulations/turtlebot3_gazebo

아래의 사진에서 보면 launch 폴더안에 있는 파일로 인해 실행이 되어있음을 알수 있다. launch 파일내에 turtlebot3_world.launch 내용을 확인해 보자.

2-1) turtlebot3_world.launch 파일

// turtlebot3_world.launch 파일
<launch>
  // 위에서 export 한 model를 불러오는 과정
  <arg name="model" default="$(env TURTLEBOT3_MODEL)" doc="model type [burger, waffle, waffle_pi]"/>
  <arg name="x_pos" default="-2.0"/>
  <arg name="y_pos" default="-0.5"/>
  <arg name="z_pos" default="0.0"/>

  // 실행 시 gazebo_ros 패키지에서 우선 empty_world를 불러오게 되며, arg를 통해
  // 아래의 world값을 turtlebot3_world.world파일로 불러오는 것을 알 수있음
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find turtlebot3_gazebo)/worlds/turtlebot3_world.world"/>
    <arg name="paused" value="false"/>
    <arg name="use_sim_time" value="true"/>
    <arg name="gui" value="true"/>
    <arg name="headless" value="false"/>
    <arg name="debug" value="false"/>
  </include>

  <param name="robot_description" command="$(find xacro)/xacro $(find turtlebot3_description)/urdf/turtlebot3_$(arg model).urdf.xacro" />

  <node pkg="gazebo_ros" type="spawn_model" name="spawn_urdf"  args="-urdf -model turtlebot3_$(arg model) -x $(arg x_pos) -y $(arg y_pos) -z $(arg z_pos) -param robot_description" />
</launch>

 

실행시 gazebo_ros의 empty world가 실행되며 이 때 turtlebot3_world.world가 실행되는 것을 확인할 수 있다.

아래의 파일에서 실제 모델의 정보를 불러오게 되는데 기본적으로 world파일로 부터 실행되는 것들은 위의 폴더 중 models에 들어있다. 

위의 world.launch 파일을 정리하면 

1)turtlebot3_world.world 가 실행되고

2) gazebo_ros 패키지 실행 시에 위의 robot_description이 같이 실행되게 된다. 아래서 코드로 확인할테니지만 여기 urdf 파일을 살펴보면 gazebo_plugin이 들어 있으며, 여기서 publish 하는 토픽들이 들어간다.

각각의 코드를 보도록 하자.

 

- turtlebot3_world.world 파일 

-> 여기서는 world에 있는 지형 지물에 관계된 것이 설정된다. model :// 폴더명이 결국 불러오는 지형지물의 모델이며,

여기서는 turtlebot3_gazebo/models/turtlebot3_world 폴더에 해당한다. 

// turtlebot3_world.world 파일
// models 폴더내 turtlebot3_world와 동일한 이름의 폴더가 있으며 그안에 
// 실제 모델에 대한 정보가 들어있는 model.config 와 model.sdf 파일이 있다.
//아래 sdf version은 model.config에서 정의되어 있으며 현재는 1.4 버전을 사용한다.
<sdf version='1.4'>
 // default 값을 셋팅하며 그라운드와 조명을 넣을 수 있다.
  <world name='default'>
    <!-- A global light source -->
    <include>
      <uri>model://sun</uri>
    </include>

    <!-- A ground plane -->
    <include>
      <uri>model://ground_plane</uri>
    </include>

    <physics type="ode">
      <real_time_update_rate>1000.0</real_time_update_rate>
      <max_step_size>0.001</max_step_size>
      <real_time_factor>1</real_time_factor>
      <ode>
        <solver>
          <type>quick</type>
          <iters>150</iters>
          <precon_iters>0</precon_iters>
          <sor>1.400000</sor>
          <use_dynamic_moi_rescaling>1</use_dynamic_moi_rescaling>
        </solver>
        <constraints>
          <cfm>0.00001</cfm>
          <erp>0.2</erp>
          <contact_max_correcting_vel>2000.000000</contact_max_correcting_vel>
          <contact_surface_layer>0.01000</contact_surface_layer>
        </constraints>
      </ode>
    </physics>

   // 여기서 실제 모델을 불러오는 데 model :// 모델이름이 된다.
   // 이때 모델이름 = models/폴더이름 값이 된다. 파일명이 아닌 폴더명이다.
    <!-- Load world -->
    <include>
      <uri>model://turtlebot3_world</uri>
    </include>

    <scene>
      <ambient>0.4 0.4 0.4 1</ambient>
      <background>0.7 0.7 0.7 1</background>
      <shadows>true</shadows>
    </scene>

    <gui fullscreen='0'>
      <camera name='user_camera'>
        <pose>0.8 0.0 12.0 0 1.5708 0</pose>
        <view_controller>orbit</view_controller>
      </camera>
    </gui>
  </world>
</sdf>

- model-1_4.sdf 파일 ( 위에서 생성되는 world에 들어가는 지형지물에 대한 것이 들어있다)

// model-1_4.sdf 파일
// 실제 모델에 대한 정보는 여기에서 작성된다.
// link joint 등을 통해 실제 turtlebot 모델을 만든다.
<sdf version='1.4'>
    <!-- Draw Circle -->
    <model name='ros_symbol'>
      <static>1</static>
      <link name='symbol'>
        <collision name='one_one'>
          <pose>-1.1 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='one_one'>
          <pose>-1.1 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='one_two'>
          <pose>-1.1 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='one_two'>
          <pose>-1.1 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='one_three'>
          <pose>-1.1 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='one_three'>
          <pose>-1.1 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='two_one'>
          <pose>0 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='two_one'>
          <pose>0 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='two_two'>
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='two_two'>
          <pose>0 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='two_three'>
          <pose>0 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='two_three'>
          <pose>0 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='three_one'>
          <pose>1.1 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='three_one'>
          <pose>1.1 -1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='three_two'>
          <pose>1.1 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='three_two'>
          <pose>1.1 0 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <collision name='three_three'>
          <pose>1.1 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='three_three'>
          <pose>1.1 1.1 0.25 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.15</radius>
              <length>0.5</length>
            </cylinder>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/White</name>
            </script>
          </material>
        </visual>

        <!-- Draw Hexagon -->
        <collision name='head'>
          <pose>3.5 0 -0.5 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.8 0.8 0.8</scale>
            </mesh>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='head'>
          <pose>3.5 0 -0.5 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.8 0.8 0.8</scale>
            </mesh>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Green</name>
            </script>
          </material>
        </visual>

        <collision name='left_hand'>
          <pose>1.8 2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='left_hand'>
          <pose>1.8 2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Green</name>
            </script>
          </material>
        </visual>

        <collision name='right_hand'>
          <pose>1.8 -2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='right_hand'>
          <pose>1.8 -2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Green</name>
            </script>
          </material>
        </visual>

        <collision name='left_foot'>
          <pose>-1.8 2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='left_foot'>
          <pose>-1.8 2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Green</name>
            </script>
          </material>
        </visual>

        <collision name='right_foot'>
          <pose>-1.8 -2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <max_contacts>10</max_contacts>
          <surface>
            <bounce/>
            <friction>
              <ode/>
            </friction>
            <contact>
              <ode/>
            </contact>
          </surface>
        </collision>

        <visual name='right_foot'>
          <pose>-1.8 -2.7 0 0 0 0</pose>
          <geometry>
            <mesh>
              <uri>model://turtlebot3_world/meshes/hexagon.dae</uri>
              <scale>0.55 0.55 0.55</scale>
            </mesh>
          </geometry>
          <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Green</name>
            </script>
          </material>
        </visual>

        <!-- Draw Wall -->
        <collision name='body'>
        <pose>0 0 -0.3 0 0 -1.5708</pose>
        <geometry>
          <mesh>
            <uri>model://turtlebot3_world/meshes/wall.dae</uri>
            <scale>0.25 0.25 0.25</scale>
          </mesh>
        </geometry>
        <max_contacts>10</max_contacts>
        <surface>
          <bounce/>
          <friction>
            <ode/>
          </friction>
          <contact>
            <ode/>
          </contact>
        </surface>
      </collision>

      <visual name='body'>
        <pose>0 0 -0.3 0 0 -1.5708</pose>
        <geometry>
          <mesh>
            <uri>model://turtlebot3_world/meshes/wall.dae</uri>
            <scale>0.25 0.25 0.25</scale>
          </mesh>
        </geometry>
        <material>
          <script>
            <uri>file://media/materials/scripts/gazebo.material</uri>
            <name>Gazebo/FlatBlack</name>
          </script>
        </material>
      </visual>
    </link>
  </model>
</sdf>

위의 sdf 파일을 보면 body / left_foot / right_foot 등 각각의 파츠를 만드는 부분이 보인다. 추후에 실제 모델을 만들게 된다면 sdf 또는 urdf 파일을 통해 모델의 형태를 정의할 수 있다.

 

- robot_description / urdf 파일 ( turtlebot3_description/urdf/turtlebot3_$(arg model).urdf.xacro

<?xml version="1.0" ?>
<robot name="turtlebot3_waffle" xmlns:xacro="http://ros.org/wiki/xacro">

// 파일 실행시 아래의 common_properties.xacro와 turtlebot3_waffle.gazebo.xacro 파일이
// 둘다 실행하게 된다. 여기서 common_properties는 공통색깔에 대한 것이 지정되어 있으며
// turtlebot3_waffle.gazebo.xacro에서는 <gazebo> 플러그인에 대한 것도 들어있다. 이파일이 중요하다

  <xacro:include filename="$(find turtlebot3_description)/urdf/common_properties.xacro"/>
  <xacro:include filename="$(find turtlebot3_description)/urdf/turtlebot3_waffle.gazebo.xacro"/>

  <xacro:property name="r200_cam_rgb_px" value="0.005"/>
  <xacro:property name="r200_cam_rgb_py" value="0.018"/>
  <xacro:property name="r200_cam_rgb_pz" value="0.013"/>
  <xacro:property name="r200_cam_depth_offset" value="0.01"/>

  <link name="base_footprint"/>

  <joint name="base_joint" type="fixed">
    <parent link="base_footprint"/>
    <child link="base_link" />
    <origin xyz="0 0 0.010" rpy="0 0 0"/>
  </joint>

  <link name="base_link">
    <visual>
      <origin xyz="-0.064 0 0.0" rpy="0 0 0"/>
      <geometry>
        <mesh filename="package://turtlebot3_description/meshes/bases/waffle_base.stl" scale="0.001 0.001 0.001"/>
      </geometry>
      <material name="light_black"/>
    </visual>

    <collision>
      <origin xyz="-0.064 0 0.047" rpy="0 0 0"/>
      <geometry>
        <box size="0.266 0.266 0.094"/>
      </geometry>
    </collision>
    
    <inertial>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <mass value="1.3729096e+00"/>
      <inertia ixx="8.7002718e-03" ixy="-4.7576583e-05" ixz="1.1160499e-04"
               iyy="8.6195418e-03" iyz="-3.5422299e-06"
               izz="1.4612727e-02" />
    </inertial>
  </link>

  <joint name="wheel_left_joint" type="continuous">
    <parent link="base_link"/>
    <child link="wheel_left_link"/>
    <origin xyz="0.0 0.144 0.023" rpy="-1.57 0 0"/>
    <axis xyz="0 0 1"/>
  </joint>

  <link name="wheel_left_link">
    <visual>
      <origin xyz="0 0 0" rpy="1.57 0 0"/>
      <geometry>
        <mesh filename="package://turtlebot3_description/meshes/wheels/left_tire.stl" scale="0.001 0.001 0.001"/>
      </geometry>
      <material name="dark"/>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <cylinder length="0.018" radius="0.033"/>
      </geometry>
    </collision>

    <inertial>
      <origin xyz="0 0 0" />
      <mass value="2.8498940e-02" />
      <inertia ixx="1.1175580e-05" ixy="-4.2369783e-11" ixz="-5.9381719e-09"
               iyy="1.1192413e-05" iyz="-1.4400107e-11"
               izz="2.0712558e-05" />
      </inertial>
  </link>

  <joint name="wheel_right_joint" type="continuous">
    <parent link="base_link"/>
    <child link="wheel_right_link"/>
    <origin xyz="0.0 -0.144 0.023" rpy="-1.57 0 0"/>
    <axis xyz="0 0 1"/>
  </joint>

  <link name="wheel_right_link">
    <visual>
      <origin xyz="0 0 0" rpy="1.57 0 0"/>
      <geometry>
        <mesh filename="package://turtlebot3_description/meshes/wheels/right_tire.stl" scale="0.001 0.001 0.001"/>
      </geometry>
      <material name="dark"/>
    </visual>

    <collision>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <cylinder length="0.018" radius="0.033"/>
      </geometry>
    </collision>

    <inertial>
      <origin xyz="0 0 0" />
      <mass value="2.8498940e-02" />
      <inertia ixx="1.1175580e-05" ixy="-4.2369783e-11" ixz="-5.9381719e-09"
               iyy="1.1192413e-05" iyz="-1.4400107e-11"
               izz="2.0712558e-05" />
      </inertial>
  </link>

  <joint name="caster_back_right_joint" type="fixed">
    <parent link="base_link"/>
    <child link="caster_back_right_link"/>
    <origin xyz="-0.177 -0.064 -0.004" rpy="-1.57 0 0"/>
  </joint>

  <link name="caster_back_right_link">
    <collision>
      <origin xyz="0 0.001 0" rpy="0 0 0"/>
      <geometry>
        <box size="0.030 0.009 0.020"/>
      </geometry>
    </collision>

    <inertial>
      <origin xyz="0 0 0" />
      <mass value="0.005" />
      <inertia ixx="0.001" ixy="0.0" ixz="0.0"
               iyy="0.001" iyz="0.0"
               izz="0.001" />
    </inertial>
  </link>

  <joint name="caster_back_left_joint" type="fixed">
    <parent link="base_link"/>
    <child link="caster_back_left_link"/>
    <origin xyz="-0.177 0.064 -0.004" rpy="-1.57 0 0"/>
  </joint>

  <link name="caster_back_left_link">
    <collision>
      <origin xyz="0 0.001 0" rpy="0 0 0"/>
      <geometry>
        <box size="0.030 0.009 0.020"/>
      </geometry>
    </collision>

    <inertial>
      <origin xyz="0 0 0" />
      <mass value="0.005" />
      <inertia ixx="0.001" ixy="0.0" ixz="0.0"
               iyy="0.001" iyz="0.0"
               izz="0.001" />
    </inertial>
  </link>

  <joint name="imu_joint" type="fixed">
    <parent link="base_link"/>
    <child link="imu_link"/>
    <origin xyz="0.0 0 0.068" rpy="0 0 0"/>
  </joint>

  <link name="imu_link"/>

  <joint name="scan_joint" type="fixed">
    <parent link="base_link"/>
    <child link="base_scan"/>
    <origin xyz="-0.064 0 0.122" rpy="0 0 0"/>
  </joint>

  <link name="base_scan">
    <visual>
      <origin xyz="0 0 0" rpy="0 0 0"/>
      <geometry>
        <mesh filename="package://turtlebot3_description/meshes/sensors/lds.stl" scale="0.001 0.001 0.001"/>
      </geometry>
      <material name="dark"/>
    </visual>

    <collision>
      <origin xyz="0.015 0 -0.0065" rpy="0 0 0"/>
      <geometry>
        <cylinder length="0.0315" radius="0.055"/>
      </geometry>
    </collision>

    <inertial>
      <mass value="0.114" />
      <origin xyz="0 0 0" />
      <inertia ixx="0.001" ixy="0.0" ixz="0.0"
               iyy="0.001" iyz="0.0"
               izz="0.001" />
    </inertial>
  </link>

  <joint name="camera_joint" type="fixed">
    <origin xyz="0.064 -0.065 0.094" rpy="0 0 0"/>
    <parent link="base_link"/>
    <child link="camera_link"/>
  </joint>

  <link name="camera_link">
    <visual>
     <origin xyz="0 0 0" rpy="1.57 0 1.57"/>
      <geometry>
       <mesh filename="package://turtlebot3_description/meshes/sensors/r200.dae" />
      </geometry>
    </visual>
    <collision>
      <origin xyz="0.003 0.065 0.007" rpy="0 0 0"/>
      <geometry>
        <box size="0.012 0.132 0.020"/>
      </geometry>
    </collision>

    <!-- This inertial field needs doesn't contain reliable data!! -->
<!--   <inertial>
      <mass value="0.564" />
      <origin xyz="0 0 0" />
      <inertia ixx="0.003881243" ixy="0.0" ixz="0.0"
               iyy="0.000498940" iyz="0.0"
               izz="0.003879257" />
    </inertial>-->
  </link>

  <joint name="camera_rgb_joint" type="fixed">
    <origin xyz="${r200_cam_rgb_px} ${r200_cam_rgb_py} ${r200_cam_rgb_pz}" rpy="0 0 0"/>
    <parent link="camera_link"/>
    <child link="camera_rgb_frame"/>
  </joint>
  <link name="camera_rgb_frame"/>

  <joint name="camera_rgb_optical_joint" type="fixed">
    <origin xyz="0 0 0" rpy="-1.57 0 -1.57"/>
    <parent link="camera_rgb_frame"/>
    <child link="camera_rgb_optical_frame"/>
  </joint>
  <link name="camera_rgb_optical_frame"/>

  <joint name="camera_depth_joint" type="fixed">
    <origin xyz="${r200_cam_rgb_px} ${r200_cam_rgb_py + r200_cam_depth_offset} ${r200_cam_rgb_pz}" rpy="0 0 0"/>
    <parent link="camera_link"/>
    <child link="camera_depth_frame"/>
  </joint>
  <link name="camera_depth_frame"/>

  <joint name="camera_depth_optical_joint" type="fixed">
    <origin xyz="0 0 0" rpy="-1.57 0 -1.57"/>
    <parent link="camera_depth_frame"/>
    <child link="camera_depth_optical_frame"/>
  </joint>
  <link name="camera_depth_optical_frame"/>

</robot>

위의 파일 실행시 같이 실행되는 turtlebot3_waffle.gazebo.xacro 안에 <gazebo></gazebo>안에 플러그인이 들어있다. 

gazebo 공식문서를 통해서 아래 플러그인들은  확인이 가능하며 필요에 따라 추가할 수 있다.

<?xml version="1.0"?>
<robot name="turtlebot3_waffle_sim" xmlns:xacro="http://ros.org/wiki/xacro">
  <xacro:arg name="laser_visual"  default="false"/>
  <xacro:arg name="camera_visual" default="false"/>
  <xacro:arg name="imu_visual"    default="false"/>

  <gazebo reference="base_link">
    <material>Gazebo/DarkGrey</material>
  </gazebo>

  <gazebo reference="wheel_left_link">
    <mu1>0.1</mu1>
    <mu2>0.1</mu2>
    <kp>500000.0</kp>
    <kd>10.0</kd>
    <minDepth>0.001</minDepth>
    <maxVel>0.1</maxVel>
    <fdir1>1 0 0</fdir1>
    <material>Gazebo/FlatBlack</material>
  </gazebo>

  <gazebo reference="wheel_right_link">
    <mu1>0.1</mu1>
    <mu2>0.1</mu2>
    <kp>500000.0</kp>
    <kd>10.0</kd>
    <minDepth>0.001</minDepth>
    <maxVel>0.1</maxVel>
    <fdir1>1 0 0</fdir1>
    <material>Gazebo/FlatBlack</material>
  </gazebo>

  <gazebo reference="caster_back_right_link">
    <mu1>0.1</mu1>
    <mu2>0.1</mu2>
    <kp>1000000.0</kp>
    <kd>100.0</kd>
    <minDepth>0.001</minDepth>
    <maxVel>1.0</maxVel>
    <material>Gazebo/FlatBlack</material>
  </gazebo>

  <gazebo reference="caster_back_left_link">
    <mu1>0.1</mu1>
    <mu2>0.1</mu2>
    <kp>1000000.0</kp>
    <kd>100.0</kd>
    <minDepth>0.001</minDepth>
    <maxVel>1.0</maxVel>
    <material>Gazebo/FlatBlack</material>
  </gazebo>

  <gazebo reference="imu_link">
    <sensor type="imu" name="imu">
      <always_on>true</always_on>
      <visualize>$(arg imu_visual)</visualize>
    </sensor>
    <material>Gazebo/Grey</material>
  </gazebo>

  <gazebo>
    <plugin name="turtlebot3_waffle_controller" filename="libgazebo_ros_diff_drive.so">
      <commandTopic>cmd_vel</commandTopic>
      <odometryTopic>odom</odometryTopic>
      <odometryFrame>odom</odometryFrame>
      <odometrySource>world</odometrySource>
      <publishOdomTF>true</publishOdomTF>
      <robotBaseFrame>base_footprint</robotBaseFrame>
      <publishWheelTF>false</publishWheelTF>
      <publishTf>true</publishTf>
      <publishWheelJointState>true</publishWheelJointState>
      <legacyMode>false</legacyMode>
      <updateRate>30</updateRate>
      <leftJoint>wheel_left_joint</leftJoint>
      <rightJoint>wheel_right_joint</rightJoint>
      <wheelSeparation>0.287</wheelSeparation>
      <wheelDiameter>0.066</wheelDiameter>
      <wheelAcceleration>1</wheelAcceleration>
      <wheelTorque>10</wheelTorque>
      <rosDebugLevel>na</rosDebugLevel>
    </plugin>
  </gazebo>

  <gazebo>
    <plugin name="imu_plugin" filename="libgazebo_ros_imu.so">
      <alwaysOn>true</alwaysOn>
      <bodyName>imu_link</bodyName>
      <frameName>imu_link</frameName>
      <topicName>imu</topicName>
      <serviceName>imu_service</serviceName>
      <gaussianNoise>0.0</gaussianNoise>
      <updateRate>0</updateRate>
      <imu>
        <noise>
          <type>gaussian</type>
          <rate>
            <mean>0.0</mean>
            <stddev>2e-4</stddev>
            <bias_mean>0.0000075</bias_mean>
            <bias_stddev>0.0000008</bias_stddev>
          </rate>
          <accel>
            <mean>0.0</mean>
            <stddev>1.7e-2</stddev>
            <bias_mean>0.1</bias_mean>
            <bias_stddev>0.001</bias_stddev>
          </accel>
        </noise>
      </imu>
    </plugin>
  </gazebo>

  <gazebo reference="base_scan">
    <material>Gazebo/FlatBlack</material>
    <sensor type="ray" name="lds_lfcd_sensor">
      <pose>0 0 0 0 0 0</pose>
      <visualize>$(arg laser_visual)</visualize>
      <update_rate>5</update_rate>
      <ray>
        <scan>
          <horizontal>
            <samples>360</samples>
            <resolution>1</resolution>
            <min_angle>0.0</min_angle>
            <max_angle>6.28319</max_angle>
          </horizontal>
        </scan>
        <range>
          <min>0.120</min>
          <max>3.5</max>
          <resolution>0.015</resolution>
        </range>
        <noise>
          <type>gaussian</type>
          <mean>0.0</mean>
          <stddev>0.01</stddev>
        </noise>
      </ray>
      <plugin name="gazebo_ros_lds_lfcd_controller" filename="libgazebo_ros_laser.so">
        <topicName>scan</topicName>
        <frameName>base_scan</frameName>
      </plugin>
    </sensor>
  </gazebo>

  <gazebo reference="camera_rgb_frame">
    <sensor type="depth" name="realsense_R200">
      <always_on>true</always_on>
      <visualize>$(arg camera_visual)</visualize>
      <camera>
          <horizontal_fov>1.3439</horizontal_fov>
          <image>
              <width>1920</width>
              <height>1080</height>
              <format>R8G8B8</format>
          </image>
          <depth_camera></depth_camera>
          <clip>
              <near>0.03</near>
              <far>100</far>
          </clip>
      </camera>
      <plugin name="camera_controller" filename="libgazebo_ros_openni_kinect.so">
        <baseline>0.2</baseline>
        <alwaysOn>true</alwaysOn>
        <updateRate>30.0</updateRate>
        <cameraName>camera</cameraName>
        <frameName>camera_rgb_optical_frame</frameName>
        <imageTopicName>rgb/image_raw</imageTopicName>
        <depthImageTopicName>depth/image_raw</depthImageTopicName>
        <pointCloudTopicName>depth/points</pointCloudTopicName>
        <cameraInfoTopicName>rgb/camera_info</cameraInfoTopicName>
        <depthImageCameraInfoTopicName>depth/camera_info</depthImageCameraInfoTopicName>
        <pointCloudCutoff>0.4</pointCloudCutoff>
            <hackBaseline>0.07</hackBaseline>
            <distortionK1>0.0</distortionK1>
            <distortionK2>0.0</distortionK2>
            <distortionK3>0.0</distortionK3>
            <distortionT1>0.0</distortionT1>
            <distortionT2>0.0</distortionT2>
        <CxPrime>0.0</CxPrime>
        <Cx>0.0</Cx>
        <Cy>0.0</Cy>
        <focalLength>0</focalLength>
        <hackBaseline>0</hackBaseline>
      </plugin>
    </sensor>
  </gazebo>

</robot>