平台：华硕 Thinker Edge R 瑞芯微 RK3399Pro
固件版本：Tinker_Edge_R-Debian-Stretch-V1.0.4-20200615

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记录自【古月居】古月·ROS入门21讲 | 一学就会的ROS机器人入门教程 —— 古月居GYH P19 19.launch启动文件的使用方法

Launch文件：通过XML文件实现多节点的配置和启动（可自动启动ROS Master）

Launch文件语法

$<launch>$

launch文件中的根元素采用$<$launch$>$标签定义

$<node>$

<node pkg="package-name" type="executable-name" name="node-name" />

pkg：节点所在的功能包名称
type：节点的可执行文件名称
name：节点运行时的名称
output, respawn, required, ns, args

参数设置

$<param>/<rosparam>$

设置ROS系统运行中的参数，存储在参数服务器中。

<param name="output_frame" value="odom" />

name：参数名
value：参数值
加载参数文件中的多个参数：

<rosparam file="params.yaml" command="load" ns= "params" />

$<arg>$

launch文件内部的局部变量，仅限于launch文件使用

<arg name="arg-name" default="arg-value" />

name：参数名
value：参数值
调用：

<param name="foo" value="$(arg arg-name)" />
<node name="node" pkg="package" type="type" args="$(arg arg-name)" />

$<remap>$

重映射ROS计算图资源的命名。

<remap from="/turtlebot/cmd_vel" to="/cmd_vel" />

from：原命名
to：映射之后的命名

$<include>$

包含其他launch文件，类似C语言中的头文件包含。

<include file="$(dirname)/other.launch" />

file：包含的其他launch文件路径

更多标签可参见：http://wiki.ros.org/roslaunch/XML

实验

创建功能包

cd ~/catkin_workspace/src
catkin_create_pkg learning_launch

cd learning_launch
mkdir launch

例子

simple.launch

nano ~/catkin_workspace/src/learning_launch/launch/simple.launch

<launch><node pkg="learning_topic" type="person_subscriber" name="talker" output="screen" /><node pkg="learning_topic" type="person_publisher" name="listener" output="screen" /> 
</launch>

编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roslaunch learning_launch simple.launch

turtlesim_parameter_config.launch

nano ~/catkin_workspace/src/learning_launch/launch/turtlesim_parameter_config.launch

<launch><param name="/turtle_number"   value="2"/><node pkg="turtlesim" type="turtlesim_node" name="turtlesim_node"><param name="turtle_name1"   value="Tom"/><param name="turtle_name2"   value="Jerry"/><rosparam file="$(find learning_launch)/config/param.yaml" command="load"/></node><node pkg="turtlesim" type="turtle_teleop_key" name="turtle_teleop_key" output="screen"/></launch>

mkdir ~/catkin_workspace/src/learning_launch/config
nano ~/catkin_workspace/src/learning_launch/config/param.yaml

A: 123
B: "hello"group:C: 456D: "hello"

编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roslaunch learning_launch turtlesim_parameter_config.launch

start_tf_demo_c++.launch

nano ~/catkin_workspace/src/learning_launch/launch/start_tf_demo_c++.launch

 <launch><!-- Turtlesim Node--><node pkg="turtlesim" type="turtlesim_node" name="sim"/><node pkg="turtlesim" type="turtle_teleop_key" name="teleop" output="screen"/><node pkg="learning_tf" type="turtle_tf_broadcaster" args="/turtle1" name="turtle1_tf_broadcaster" /><node pkg="learning_tf" type="turtle_tf_broadcaster" args="/turtle2" name="turtle2_tf_broadcaster" /><node pkg="learning_tf" type="turtle_tf_listener" name="listener" /></launch>

编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roslaunch learning_launch start_tf_demo_c++.launch

start_tf_demo_py.launch

nano ~/catkin_workspace/src/learning_launch/launch/start_tf_demo_py.launch

<launch><!-- Turtlesim Node--><node pkg="turtlesim" type="turtlesim_node" name="sim"/><node pkg="turtlesim" type="turtle_teleop_key" name="teleop" output="screen"/><node name="turtle1_tf_broadcaster" pkg="learning_tf" type="turtle_tf_broadcaster.py"><param name="turtle" type="string" value="turtle1" /></node><node name="turtle2_tf_broadcaster" pkg="learning_tf" type="turtle_tf_broadcaster.py"><param name="turtle" type="string" value="turtle2" /> </node><node pkg="learning_tf" type="turtle_tf_listener.py" name="listener" /></launch>

编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roslaunch learning_launch start_tf_demo_py.launch

turtlesim_remap.launch

nano ~/catkin_workspace/src/learning_launch/launch/turtlesim_remap.launch

<launch><include file="$(find learning_launch)/launch/simple.launch" /><node pkg="turtlesim" type="turtlesim_node" name="turtlesim_node"><remap from="/turtle1/cmd_vel" to="/cmd_vel"/></node></launch>

编译并运行

cd ~/catkin_workspace
catkin_make# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
roslaunch learning_launch turtlesim_remap.launch

# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph

rostopic list

rostopic pub /cmd_vel geometry_msgs/Twist "linear:x: 1.0y: 0.0z: 0.0
angular:x: 0.0y: 0.0z: 0.0"

# 新建一个终端
source ~/catkin_workspace/devel/setup.bash
rqt_graph