로봇을 불렀으면, cmd_vel 토픽으로 움직이고 싶다. 찾다보니 gazebo가 제공하는 plugin로 움직일 수 있음을 알았다. 플러그인 설정으로 어느 토픽을 읽어서 모델을 움직일지 결정한다.
https://classic.gazebosim.org/tutorials?tut=ros_gzplugins
gcamp_gazebo 샘플 프로그램을 참조 했다. gazebo로 로봇을 움직이려면 필요한 몇 개 파일을 만들어야 한다.
now0930@amd2004:~/ros_test/workspace/src/wander_bot$ tree
.
├── CMakeLists.txt
├── gazebo_world.launch
├── launch
│ ├── hello.launch
│ ├── my_world.launch
│ └── robot_description.launch
├── log.txt
├── package.xml
├── src
│ └── red_green_light.py
├── urdf
│ ├── robot.gazebo
│ ├── robot.xacro
│ └── test.urdf
└── worlds
├── my_world
└── my_world2
4 directories, 13 files
roslaunch로 launch에 있는 my_world.launch에서 시작한다.
oot@amd2004:/home/ros_test/workspace/src/wander_bot# cat launch/my_world.launch
<?xml version="1.0" encoding="UTF-8"?>
<launch>
<!-- Robot pose -->
<arg name="x" default="0"/>
<arg name="y" default="0"/>
<arg name="z" default="0"/>
<arg name="roll" default="0"/>
<arg name="pitch" default="0"/>
<arg name="yaw" default="0"/>
<arg name="model_name" default="agv_number1"/>
<!-- 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 wander_bot)/worlds/my_world2"/>
<arg name="use_sim_time" value="true"/>
<!-- more default parameters can be changed here -->
</include>
<arg name="package_name" default="wander_bot" />
<arg name="path" value="(find $(arg package_name))" />
<arg name="dollar" value="$" />
<include file="$(arg dollar)$(arg path)/launch/robot_description.launch"/>
<!-- Spawn My Robot -->
<!--
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -param robot_description -model $(arg model_name)
-x $(arg x) -y $(arg y) -z $(arg z)
-R $(arg roll) -P $(arg pitch) -Y $(arg yaw)"/>
-->
<node name="urdf_spawner" pkg="gazebo_ros" type="spawn_model" respawn="false" output="screen"
args="-urdf -param robot_description -model $(arg model_name)
-x $(arg x) -y $(arg y) -z $(arg z)
-R $(arg roll) -P $(arg pitch) -Y $(arg yaw)"/>
<node name="test_node" pkg="wander_bot" type="red_green_light.py"
args="/cmd_vel">
</node>
</launch>
<include file="$(arg dollar)$(arg path)/launch/robot_description.launch"/>
launch가 robot description을 실행하는데, command로 robot.xacro로 세부 설정을 한다. command가 아닌 다른 방식으로는 모델이 움직이지 않는다. robot description 내부에는 robot_description, joint_state_publisher, robot_state_publisher 3개를 설정한다.
now0930@amd2004:~/ros_test/workspace/src/wander_bot$ cat launch/robot_description.launch
<?xml version="1.0"?>
<launch>
<!-- send urdf to param server -->
<!-- xacro -->
<param name="robot_description" command="$(find xacro)/xacro --inorder '$(find wander_bot)/urdf/robot.xacro'" />
<!-- urdf or raw xml file -->
<!-- <param name="robot_description" command="cat $(find museumGuide)/urdf_model/peoplebot.xml" /> -->
<!-- Send fake joint values-->
<node name="joint_state_publisher" pkg="joint_state_publisher" type="joint_state_publisher">
<param name="use_gui" value="False"/>
</node>
<!-- Send robot states to tf -->
<node name="robot_state_publisher" pkg="robot_state_publisher" type="robot_state_publisher" respawn="false" output="screen"/>
</launch>
robot.xacro를 보면
now0930@amd2004:~/ros_test/workspace/src/wander_bot$ cat urdf/robot.xacro
<?xml version="1.0" ?>
<robot name="mobile_robot" xmlns:xacro="http://www.ros.org/wiki/xacro">
<material name="blue">
<color rgba = "0 0 0.8 1"/>
</material>
<material name="gray">
<color rgba = "1 1 1 1"/>
</material>
<material name="blueviolet">
<color rgba = "0.54 0.16 0.88 1"/>
</material>
<link name = "base_footprint"/>
<xacro:include filename="$(find wander_bot)/urdf/robot.gazebo" />
<link name="base_link">
<visual>
<origin xyz="0 0 0" rpy = "0 0 0"/>
<geometry>
<box size = "0.3 0.24 0.1" rpy = "0 0 0" />
</geometry>
<material name = "gray"/>
</visual>
<collision>
<origin xyz="0 0 0.03" rpy = "0 0 0"/>
<geometry>
<box size = "0.3 0.25 0.1" />
</geometry>
</collision>
<inertial>
<mass value = "1.0" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0" />
</inertial>
</link>
<joint name = "base_footprint_fixed" type = "fixed">
<origin xyz = "0 0 0.03" rpy = "0 0 0"/>
<parent link = "base_footprint"/>
<child link = "base_link"/>
</joint>
<link name = "left_wheel">
<visual>
<origin xyz = "0 0 0" rpy = "1.570796 0 0" />
<geometry>
<cylinder length = "0.05" radius = "0.08" />
</geometry>
<material name ="blue"/>
</visual>
<collision>
<origin xyz = "0 0 0" rpy = "1.570796 0 0" />
<geometry>
<cylinder length = "0.05" radius = "0.08" />
</geometry>
</collision>
<inertial>
<mass value = "1.0" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0" />
</inertial>
</link>
<link name = "right_wheel">
<visual>
<origin xyz = "0 0 0" rpy = "1.570796 0 0" />
<geometry>
<cylinder length = "0.05" radius = "0.08" />
</geometry>
<material name ="blue"/>
</visual>
<collision>
<origin xyz = "0 0 0" rpy = "1.570796 0 0" />
<geometry>
<cylinder length = "0.05" radius = "0.08" />
</geometry>
</collision>
<inertial>
<mass value = "1.0" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="1.0" iyz="0.0" izz="1.0" />
</inertial>
</link>
<joint name = "left_wheel_joint" type = "continuous">
<origin xyz = "0.1 0.15 0" rpy = "0 0 0"/>
<parent link = "base_link"/>
<child link = "left_wheel"/>
<axis xyz = "0 1 0"/>
</joint>
<joint name = "right_wheel_joint" type = "continuous">
<origin xyz = "0.1 -0.15 0" rpy = "0 0 0"/>
<parent link = "base_link"/>
<child link = "right_wheel"/>
<axis xyz = "0 1 0" />
</joint>
<link name="scanner_link">
<visual>
<origin xyz="0 0 0" rpy = "0 0 0"/>
<geometry>
<cylinder length="0.05" radius="0.035"/>
</geometry>
<material name = "blueviolet"/>
</visual>
<collision>
<origin xyz="0 0 0" rpy = "0 0 0"/>
<geometry>
<cylinder length="0.05" radius="0.035"/>
</geometry>
</collision>
<inertial>
<mass value = "1.0" />
<inertia ixx="1.0" ixy="0.0" ixz="0.0" iyy="10.0" iyz="0.0" izz="1.0" />
</inertial>
</link>
<joint name = "head_scanner" type = "fixed">
<origin xyz = "0.15 0 0" rpy = "0 1.5708 0"/>
<parent link = "base_link"/>
<child link = "scanner_link"/>
</joint>
<ros>
<namespace>/</namespace>
<argument>/cmd_vel:=cmd_vel</argument>
</ros>
</robot>
여기에 gazebo 파일을 설정해야 한다.
now0930@amd2004:~/ros_test/workspace/src/wander_bot/urdf$ cat robot.gazebo
<?xml version="1.0"?>
<robot>
<gazebo>
<plugin name="differential_drive_controller" filename="libgazebo_ros_diff_drive.so">
<legacyMode>false</legacyMode>
<updateRate>10</updateRate>
<alwaysOn>true</alwaysOn>
<leftJoint>left_wheel_joint</leftJoint>
<rightJoint>right_wheel_joint</rightJoint>
<torque>10</torque>
<robotBaseFrame>base_footprint</robotBaseFrame>
<wheelSeparation>0.4</wheelSeparation>
<wheelDiameter>0.2</wheelDiameter>
<publishWheelTF>false</publishWheelTF>
<publishTf>1</publishTf>
<commandTopic>cmd_vel</commandTopic>
<odometryTopic>odom</odometryTopic>
<odometryFrame>odom</odometryFrame>
<publishWheelJointState>false</publishWheelJointState>
<rosDebugLevel>na</rosDebugLevel>
<wheelAcceleration>0</wheelAcceleration>
<wheelTorque>5</wheelTorque>
<odometrySource>world</odometrySource>
<publishOdomTF>true</publishOdomTF>
</plugin>
</gazebo>
</robot>
모두 설정하고 roslaunch를 하면, 관성 모멘트가 잘못 되었는지 이상하게 움직인다.
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