ROS2 - tutorials

1. 环境 
 点击(此处)折叠或打开

	
	

		
		
source /opt/ros/<distro>/setup.bash ## 最好加入到 .bashrc

printenv | grep -i ROS
应该出现
ROS_VERSION=2
ROS_PYTHON_VERSION=3
ROS_DISTRO=foxy

	


当环境中有多个ROS2在跑时, 需要区别 通过 ROS_DOMAIN_ID [0-232].

	
	

	

		
		
echo "export ROS_DOMAIN_ID=" >> ~/.bashrc

	



 
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学习 turtlesim 和 rqt 工具.
sudo apt install ~nros--rqt*
然后可执行 rqt
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ROS2 graph 是 ROS 2 的网络体系.
remapping 机制允许你重新指派节点的默认属性, 包括node_name, topic_name, 
service_name 等等
 
例如 ros2 run turtlesim turtlesim_node --ros-args --remap __node:=my_turtle 
即把名称有默认的 turtle1/2/3 改成 my_turtle



ros2 topic hz / list -t / echo / info 
 
ros2 interface show geometry_msgs/msg/Twist #查看消息类型的定义
ros2 topic pub   ''
 
单次 ros2 topic pub --once /turtle1/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 2.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 1.8}}"
1Hz ros2 topic pub --rate 1 /turtle1/cmd_vel geometry_msgs/msg/Twist "{linear: {x: 2.0, y: 0.0, z: 0.0}, angular: {x: 0.0, y: 0.0, z: 1.8}}"




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ros2 service list / type  / list -t / find 
 
ros2 interface show std_srvs/srv/Empty.srv # 查看 srv 的内容.
ros2 service call   
例如 ros2 service call /spawn turtlesim/srv/Spawn "{x: 2, y: 2, theta: 0.2, name: ''}"





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ros2 param list | get   
  | set    
            | dump  被存储在 node_name.yaml 文件. 
运行时加载参数文件
 
ros2 run   --ros-args --params-file 
竟然没了 load 指令, 惊讶.
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ros2 node info /teleop_turtle  会列出发布的话题,订阅的话题, services, action servers 和 action clients.
ros2 action list -t
ros2 action info action_name # 列出action的服务端 和 客户端.
 
ros2 interface show turtlesim/action/RotateAbsolute.action
ros2 action send_goal     values应该是yaml的格式.
例如
ros2 action send_goal /turtle1/rotate_absolute turtlesim/action/RotateAbsolute "{theta: 1.57}"-----------------------------------------------------------------------------



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rqt_console 是个GUI工具. 在此你可看到日志信息,可过滤检索手机等等

ros2 run rqt_console rqt_console
日志级别: Fatal / Error / Warn / Info 默认 / Debug
设置默认日志级别.


 
ros2 run turtlesim turtlesim_node --ros-args --log-level WARN

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建立launch 文件.
1. touch launch目录/turtlesim_mimic_launch.py
内容

	
	

	

		
		
from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        Node(
            package='turtlesim',
            namespace='turtlesim1',
            executable='turtlesim_node',
            name='sim'
        ),
        Node(
            package='turtlesim',
            namespace='turtlesim2',
            executable='turtlesim_node',
            name='sim'
        ),
        Node(
            package='turtlesim',
            executable='mimic',
            name='mimic',
            remappings=[ //相当于让 turtlesim2 模拟 turtlesim 1 的动作.
                ('/input/pose', '/turtlesim1/turtle1/pose'), 相当于订阅/turtlesim1/turtle1/pose
                ('/output/cmd_vel', '/turtlesim2/turtle1/cmd_vel'), 发布到/turtlesim2/turtle1/cmd_vel
            ]
        )
    ])

	



 
ros2 launch  
ros2 launch turtlesim_mimic_launch.py 如果launch文件在当前目录下的情况


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sudo apt-get install ros--ros2bag ros--rosbag2*
ros2 bag record  产生一个 rosbag2-时间点 的文件.
ros2 bag record -o 录音名称 /topic1 /topic2
ros2 bag info 
ros2 bag play 
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