ros topic 测试实例

1、打开 launch 文件，启动仿真环境

• 执行这个 launch 文件前就别执行 turtlebot_bringup minimal.launch 那个了，不然会冲突

roscore
roslaunch robot_sim_demo robot_spawn.launch # 执行

itx@turtlebot:~$ roslaunch robot_sim_demo robot_spawn.launch 
... logging to /home/itx/.ros/log/649056f4-0fe8-11e9-a894-74de2b44b71c/roslaunch-turtlebot-24669.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://10.180.179.209:45301/

SUMMARY
========

PARAMETERS
 * /cmd_vel_mux/yaml_cfg_file: /home/itx/tutoria...
 * /robot_description: 
 * /rosdistro: kinetic
 * /rosversion: 1.12.14
 * /use_sim_time: True
 * /xbot/joint_state_controller/publish_rate: 50
 * /xbot/joint_state_controller/type: joint_state_contr...
 * /xbot/pitch_platform_position_controller/joint: yaw_to_pitch_plat...
 * /xbot/pitch_platform_position_controller/pid/d: 10.0
 * /xbot/pitch_platform_position_controller/pid/i: 0.01
 * /xbot/pitch_platform_position_controller/pid/p: 100.0
 * /xbot/pitch_platform_position_controller/type: effort_controller...
 * /xbot/robot_state_publisher/publish_frequency: 20.0
 * /xbot/yaw_platform_position_controller/joint: base_to_yaw_platform
 * /xbot/yaw_platform_position_controller/pid/d: 10.0
 * /xbot/yaw_platform_position_controller/pid/i: 0.01
 * /xbot/yaw_platform_position_controller/pid/p: 100.0
 * /xbot/yaw_platform_position_controller/type: effort_controller...

NODES # 划分了 nodes 属于不同的 node 归属
  /xbot/
    robot_state_publisher (robot_state_publisher/robot_state_publisher)
    spawner (controller_manager/spawner)
  /
    cmd_vel_mux (nodelet/nodelet)
    gazebo (gazebo_ros/gzserver)
    gazebo_gui (gazebo_ros/gzclient)
    mobile_base_nodelet_manager (nodelet/nodelet)
    urdf_spawner (gazebo_ros/spawn_model)

ROS_MASTER_URI=http://localhost:11311

# nodes 启动的 process 7个
process[gazebo-1]: started with pid [24689]
process[gazebo_gui-2]: started with pid [24694]
process[urdf_spawner-3]: started with pid [24699]
process[xbot/spawner-4]: started with pid [24700]
process[xbot/robot_state_publisher-5]: started with pid [24701]
process[mobile_base_nodelet_manager-6]: started with pid [24703]
process[cmd_vel_mux-7]: started with pid [24718]

2、查看所有的 Topic

• 注意这里的 camera 是仿真的
• turtlebot_bringup minimal.launch 里指定了 3D sensor，提供了相机传递 image 的 topic

itx@turtlebot:~$ rostopic list
/camera/depth/camera_info
/camera/depth/image_raw  # 深度图
/camera/depth/points
/camera/parameter_descriptions
/camera/parameter_updates
/camera/rgb/camera_info
/camera/rgb/image_raw  # rgb图
/camera/rgb/image_raw/compressed
/camera/rgb/image_raw/compressed/parameter_descriptions
/camera/rgb/image_raw/compressed/parameter_updates
/camera/rgb/image_raw/compressedDepth
/camera/rgb/image_raw/compressedDepth/parameter_descriptions
/camera/rgb/image_raw/compressedDepth/parameter_updates
/camera/rgb/image_raw/theora
/camera/rgb/image_raw/theora/parameter_descriptions
/camera/rgb/image_raw/theora/parameter_updates
/clock
/cmd_vel
/cmd_vel_mux/active # 多路速度控制器，选择多个信号中的一个作为输入转发到单行设备
/cmd_vel_mux/input/avoid
/cmd_vel_mux/input/navi
/cmd_vel_mux/input/safety_controller
/cmd_vel_mux/input/switch
/cmd_vel_mux/input/teleop
/cmd_vel_mux/parameter_descriptions
/cmd_vel_mux/parameter_updates
/gazebo/link_states
/gazebo/model_states
/gazebo/parameter_descriptions
/gazebo/parameter_updates
/gazebo/set_link_state
/gazebo/set_model_state
/gazebo_gui/parameter_descriptions
/gazebo_gui/parameter_updates
/imu
/joint_states
/mobile_base_nodelet_manager/bond
/odom
/rosout
/rosout_agg
/scan
/tf  # transform 坐标系转换
/tf_static
/xbot/joint_states
/xbot/pitch_platform_position_controller/command
/xbot/pitch_platform_position_controller/pid/parameter_descriptions
/xbot/pitch_platform_position_controller/pid/parameter_updates
/xbot/pitch_platform_position_controller/state
/xbot/yaw_platform_position_controller/command
/xbot/yaw_platform_position_controller/pid/parameter_descriptions
/xbot/yaw_platform_position_controller/pid/parameter_updates
/xbot/yaw_platform_position_controller/state

3、显示 /camera/rgb/image_raw 这个 topic 的属性信息

topic 里包含了以下 3 种信息

• 信息类型
• 发布者
• 订阅者

itx@turtlebot:~$ rostopic info /camera/rgb/image_raw
Type: sensor_msgs/Image  # 类型

Publishers: # 发布者
 * /gazebo (http://10.180.179.209:41085/) # 这是 1个node

Subscribers: None  # 接收者

由此可知，此时并没有订阅者。

4、用 image_view 作为订阅者接收消息

rosrun image_view image_view image:=/camera/rgb/image_raw # image:= 这里 image 在下面 nodelet_plugins.xml 定义了
[ INFO] [1546616959.571473531, 7864.310000000]: Using transport "raw"

$ rosrun [--prefix cmd] [--debug] pkg_name node_name [ARGS]  # rosrun 语法结构

查看一下 image_view 这个 package

itx@turtlebot:~$ roscd image_view/
itx@turtlebot:/opt/ros/kinetic/share/image_view$ ls
cmake  nodelet_plugins.xml  package.xml

itx@turtlebot:/opt/ros/kinetic/share/image_view$ cat nodelet_plugins.xml 

  
  
    Nodelet to view a sensor_msgs/Image topic
  
  
  
    Nodelet to view a stereo_msgs/DisparityImage topic
  

可以看到新增了两个 node

itx@turtlebot:~$ rosnode list
/cmd_vel_mux
/gazebo
/gazebo_gui
/image_view_1546616674359947887  # image_view
/image_view_1546616958807306805  # image_view
/mobile_base_nodelet_manager
/rosout
/turtlebot_teleop_keyboard
/xbot/robot_state_publisher
/xbot/spawner

再次查看 topic info

itx@turtlebot:~$ rostopic info /camera/rgb/image_raw
Type: sensor_msgs/Image

Publishers: 
 * /gazebo (http://10.180.179.209:41085/)

Subscribers: 
 * /image_view_1546616958807306805 (http://10.180.179.209:43049/)

此时已经有 Subscribers 了。