로봇을 불렀으면, cmd_vel 토픽으로 움직이고 싶다. 찾다보니 gazebo가 제공하는 plugin로 움직일 수 있음을 알았다. 플러그인 설정으로 어느 토픽을 읽어서 모델을 움직일지 결정한다.
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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