gazebo_world_modeling_intro.md

Intro to Gazebo World Modeling

Video Tutorial at https://youtu.be/gpk8mQhhI4s

Add the Open Gazebo Models Database

Use git to get a bunch of open source gazebo models from the Open Source Robotics Foundation (OSRF)

git clone https://github.com/osrf/gazebo_models.git

Add Models path to the bashrc

echo 'export GAZEBO_MODEL_PATH=~/gazebo_ws/gazebo_models:${GAZEBO_MODEL_PATH}' >> ~/.bashrc
source ~/.bashrc

A New Drone Simulation World

make a new file in ~/catkin_ws/src/iq_sim/worlds/ called hills.world

copy the following lines into the world

<?xml version="1.0" ?>
<sdf version="1.6">
  <world name="default">
    <physics type="ode">
      <ode>
        <solver>
          <type>quick</type>
          <iters>100</iters>
          <sor>1.0</sor>
        </solver>
        <constraints>
          <cfm>0.0</cfm>
          <erp>0.9</erp>
          <contact_max_correcting_vel>0.1</contact_max_correcting_vel>
          <contact_surface_layer>0.0</contact_surface_layer>
        </constraints>
      </ode>
      <real_time_update_rate>-1</real_time_update_rate>
      <!-- <max_step_size>0.0020</max_step_size> -->
    </physics>

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

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

    <model name="iris">
      <include>
        <uri>model://iris_with_standoffs_demo</uri>
      </include>






      <!-- add new camera -->
      <link name='camera'>
        <pose>0 -0.01 0.070 .8 0 1.57</pose>
        <inertial>
          <pose>0 0 0 0 0 0</pose>
          <mass>0.1</mass>
          <inertia>
            <ixx>0.001</ixx>
            <ixy>0</ixy>
            <ixz>0</ixz>
            <iyy>0.001</iyy>
            <iyz>0</iyz>
            <izz>0.001</izz>
          </inertia>
        </inertial>
        <visual name='visual'>
          <pose>0 0 0 0 0 0</pose>
          <geometry>
            <cylinder>
              <radius>0.025</radius>
              <length>0.025</length>
            </cylinder>
          </geometry>
           <material>
            <script>
              <uri>file://media/materials/scripts/gazebo.material</uri>
              <name>Gazebo/Grey</name>
            </script>
          </material>
        </visual>

        <sensor name="camera" type="camera">
          <pose>0 0 0 -1.57 -1.57 0</pose>
          <camera>
            <horizontal_fov>1.0472</horizontal_fov>
            <image>
              <width>640</width>
              <height>480</height>
            </image>
            <clip>
              <near>0.05</near>
              <far>1000</far>
            </clip>
          </camera>
          <always_on>1</always_on>
          <update_rate>10</update_rate>
          <visualize>true</visualize>

         <!--  <plugin name="irlock" filename="libArduCopterIRLockPlugin.so">
              <fiducial>irlock_beacon_01</fiducial>
          </plugin> -->
          <plugin name="camera_controller" filename="libgazebo_ros_camera.so">
          <alwaysOn>true</alwaysOn>
          <updateRate>0.0</updateRate>
          <cameraName>webcam</cameraName>
          <imageTopicName>image_raw</imageTopicName>
          <cameraInfoTopicName>camera_info</cameraInfoTopicName>
          <frameName>camera_link</frameName>
          <hackBaseline>0.07</hackBaseline>
          <distortionK1>0.0</distortionK1>
          <distortionK2>0.0</distortionK2>
          <distortionK3>0.0</distortionK3>
          <distortionT1>0.0</distortionT1>
          <distortionT2>0.0</distortionT2>
      </plugin>

        </sensor>

      </link>

      <!-- attach camera -->
      <joint type="revolute" name="base_camera_joint">
        <pose>0 0 0.0 0 0 0</pose>
        <parent>iris::iris_demo::gimbal_small_2d::tilt_link</parent>
        <child>camera</child>
        <axis>
          <limit>
            <lower>0</lower>
            <upper>0</upper>
          </limit>
          <xyz>0 0 1</xyz>
          <use_parent_model_frame>true</use_parent_model_frame>
        </axis>
      </joint>
    </model>

  </world>
</sdf>

The above code is sdf code. it is a formatting language specific to Gazebo. The above lines form the basis to our a good gazebo drone simulation. The physics tag above is tailored to best simulate the drone's flight. The next part of the simulation is the iris which is our drone. The code inside the iris model tag is the code needed for our camera sensor. We will go over sdf coding in future tutorials.

Add a Launch File to Facilitate the ROS Plugins

make a file in ~/catkin_ws/src/iq_sim/launch called hills.launch

then add the following lines

<launch>
  <!-- We resume the logic in empty_world.launch, changing only the name of the world to be launched -->
  <include file="$(find gazebo_ros)/launch/empty_world.launch">
    <arg name="world_name" value="$(find iq_sim)/worlds/hills.world"/>
    <!-- more default parameters can be changed here -->
  </include>
</launch>

save the files ( ctrl + s )

Launch the New World

roslaunch iq_sim hills.launch

Add Other Models

click on the Insert tab in the left column

add the model Winding Valley Heightmap

delete the model Ground Plane

add the model standing person

reposition the models as seen fit

save file and override our file hills.world

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References

http://gazebosim.org/tutorials