使用機(jī)器人操作系統(tǒng)ROS 2和仿真軟件Gazebo 9命令遙控可視化教程（二）

上一篇，已經(jīng)在Gazebo 9中放入了一個(gè)支持ROS 2的仿真機(jī)器人，具體參考：

使用機(jī)器人操作系統(tǒng)ROS 2和仿真軟件Gazebo 9搭建機(jī)器人教程（一）

本篇，通過此案例學(xué)習(xí)并熟練掌握ROS2的如下內(nèi)容：

ROS2常用命令回顧

遙控機(jī)器人在環(huán)境中運(yùn)動(dòng)

rqt和rviz2

攝像頭圖像顯示和激光數(shù)據(jù)可視化

ROS2入門介紹參考：https://zhuanlan.zhihu.com/p/96940278

$ ros2 launch mobot world.launch.py

具體流程參考下圖，配置不同會(huì)有路徑和目錄的差異：

節(jié)點(diǎn)

$ ros2 node

usage: ros2 node [-h]

Call `ros2 node -h` for more detailed usage. ...

Various node related sub-commands

optional arguments:

-h, --help ? ? ? ? ? ?show this help message and exit

Commands:

info ?Output information about a node

list ?Output a list of available nodes

Call `ros2 node -h` for more detailed usage.

使用其中l(wèi)ist：

$ ros2 node list

/launch_ros

/gazebo

/mobot/camera_controller

/mobot/gazebo_ros_head_hokuyo_controller

/mobot/skid_steer_drive_controller

第一個(gè)為ros接口，第二個(gè)為gazebo，第三到五個(gè)，為Gazebo插件的控制器對(duì)應(yīng)攝像頭、激光測(cè)距和運(yùn)動(dòng)驅(qū)動(dòng)。

如果需要查看更具體的節(jié)點(diǎn)信息，如camera：

$ ros2 node info /mobot/camera_controller

/mobot/camera_controller

Subscribers:

/clock: rosgraph_msgs/msg/Clock

/mobot/parameter_events: rcl_interfaces/msg/ParameterEvent

Publishers:

/mobot/camera/image: sensor_msgs/msg/Image

/mobot/camera/image/camera_info: sensor_msgs/msg/CameraInfo

/mobot/parameter_events: rcl_interfaces/msg/ParameterEvent

/mobot/rosout: rcl_interfaces/msg/Log

Services:

/mobot/camera_controller/describe_parameters: rcl_interfaces/srv/DescribeParameters

/mobot/camera_controller/get_parameter_types: rcl_interfaces/srv/GetParameterTypes

/mobot/camera_controller/get_parameters: rcl_interfaces/srv/GetParameters

/mobot/camera_controller/list_parameters: rcl_interfaces/srv/ListParameters

/mobot/camera_controller/set_parameters: rcl_interfaces/srv/SetParameters

/mobot/camera_controller/set_parameters_atomically: rcl_interfaces/srv/SetParametersAtomically

/mobot/set_camera_info: sensor_msgs/srv/SetCameraInfo

此處需要注意，Dashing和Eloquent信息有一些的差異哦！

如果使用是Eloquent，如下：

$ ros2 node info /mobot/camera_controller

/mobot/camera_controller

Subscribers:

/clock: rosgraph_msgs/msg/Clock

/mobot/parameter_events: rcl_interfaces/msg/ParameterEvent

Publishers:

/mobot/camera/image: sensor_msgs/msg/Image

/mobot/camera/image/camera_info: sensor_msgs/msg/CameraInfo

/mobot/parameter_events: rcl_interfaces/msg/ParameterEvent

/mobot/rosout: rcl_interfaces/msg/Log

Service Servers:

/mobot/camera_controller/describe_parameters: rcl_interfaces/srv/DescribeParameters

/mobot/camera_controller/get_parameter_types: rcl_interfaces/srv/GetParameterTypes

/mobot/camera_controller/get_parameters: rcl_interfaces/srv/GetParameters

/mobot/camera_controller/list_parameters: rcl_interfaces/srv/ListParameters

/mobot/camera_controller/set_parameters: rcl_interfaces/srv/SetParameters

/mobot/camera_controller/set_parameters_atomically: rcl_interfaces/srv/SetParametersAtomically

/mobot/set_camera_info: sensor_msgs/srv/SetCameraInfo

Service Clients:

Action Servers:

Action Clients:

如上所見，該節(jié)點(diǎn)正在發(fā)布、訂閱和由該節(jié)點(diǎn)提供的服務(wù)以及該節(jié)點(diǎn)充當(dāng)客戶端的服務(wù)的所有主題都會(huì)列出。

主題

$ ros2 topic

usage: ros2 topic [-h] [--include-hidden-topics]

Call `ros2 topic -h` for more detailed usage. ...

Various topic related sub-commands

optional arguments:

-h, --help ? ? ? ? ? ?show this help message and exit

--include-hidden-topics

Consider hidden topics as well

Commands:

bw ? ? Display bandwidth used by topic

delay ?Display delay of topic from timestamp in header

echo ? Output messages from a topic

find ? Output a list of available topics of a given type

hz ? ? Print the average publishing rate to screen

info ? Print information about a topic

list ? Output a list of available topics

pub ? ?Publish a message to a topic

type ? Print a topic's type

Call `ros2 topic -h` for more detailed usage.

例如list：

$ ros2 topic list

/clock

/mobot/camera/image

/mobot/camera/image/camera_info

/mobot/cmd_vel

/mobot/odom

/mobot/parameter_events

/mobot/rosout

/mobot/scan

/parameter_events

/rosout

/tf

來看看圖像數(shù)據(jù)和激光數(shù)據(jù)需要的帶寬吧？

$ ros2 topic bw /mobot/camera/image

Subscribed to [/mobot/camera/image]

average: 27.89MB/s

mean: 1.92MB/s min: 1.92MB/s max: 1.92MB/s window: 12

average: 28.39MB/s

mean: 1.92MB/s min: 1.92MB/s max: 1.92MB/s window: 27

average: 25.82MB/s

mean: 1.92MB/s min: 1.92MB/s max: 1.92MB/s window: 38

average: 26.60MB/s

mean: 1.92MB/s min: 1.92MB/s max: 1.92MB/s window: 53

ros2 topic bw /mobot/scan

Subscribed to [/mobot/scan]

average: 169.85KB/s

mean: 5.83KB/s min: 5.83KB/s max: 5.83KB/s window: 29

average: 163.58KB/s

mean: 5.83KB/s min: 5.83KB/s max: 5.83KB/s window: 56

average: 163.45KB/s

mean: 5.83KB/s min: 5.83KB/s max: 5.83KB/s window: 84

average: 164.86KB/s

mean: 5.83KB/s min: 5.83KB/s max: 5.83KB/s window: 100

再比如：

$ ros2 topic info /mobot/cmd_vel

Type: geometry_msgs/msg/Twist

Publisher count: 0

Subscriber count: 1

如果發(fā)布消息告知機(jī)器人運(yùn)動(dòng)呢？

/mobot/skid_steer_drive_controller訂閱/mobot/cmd_vel

目前，沒有消息發(fā)布，使用teleop_twist_keyboard。

服務(wù)

此部分教程不涉及，后續(xù)補(bǔ)充^_^

基礎(chǔ)知識(shí)參考：https://blog.csdn.net/zhangrelay/article/details/103493612

參數(shù)

默認(rèn)節(jié)點(diǎn)通過修改參數(shù)可提高通用性！

Dashing：

sudo apt install ros-dashing-teleop-twist-keyboard

Eloquent：

sudo apt install ros-eloquent-teleop-twist-keyboard

命令：

$ ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r __ns:=/mobot

This node takes keypresses from the keyboard and publishes them

as Twist messages. It works best with a US keyboard layout.

---------------------------

Moving around:

u ? ?i ? ?o

j ? ?k ? ?l

m ? ?, ? ?.

For Holonomic mode (strafing), hold down the shift key:

---------------------------

U ? ?I ? ?O

J ? ?K ? ?L

M ? ?< ? ?>

t : up (+z)

b : down (-z)

anything else : stop

q/z : increase/decrease max speeds by 10%

w/x : increase/decrease only linear speed by 10%

e/c : increase/decrease only angular speed by 10%

CTRL-C to quit

currently:?? ?speed 0.5?? ?turn 1.0

這部分和工具同步給出示例。

使用鍵盤可以控制機(jī)器人在環(huán)境中運(yùn)動(dòng)，觀察rqt和rviz2的變化。

遙控靠近白色球體，轉(zhuǎn)到工具章節(jié)。

行動(dòng)

此部分教程不涉及，后續(xù)補(bǔ)充^_^

基礎(chǔ)知識(shí)參考：https://blog.csdn.net/zhangrelay/article/details/103496999

啟動(dòng)

此部分教程不涉及，后續(xù)補(bǔ)充^_^

基礎(chǔ)知識(shí)參考：https://blog.csdn.net/ZhangRelay/article/details/103498784

工具

rqt和rviz2。

節(jié)點(diǎn)圖

攝像頭圖像（Gazebo時(shí)間2:31:57）

激光數(shù)據(jù)可視化（Gazebo時(shí)間2:31:57）

攝像頭圖像（Gazebo時(shí)間2:46:31）

激光數(shù)據(jù)可視化（Gazebo時(shí)間2:46:31）

接下來，將會(huì)繼續(xù)介紹使用C++節(jié)點(diǎn)編寫程序處理激光和圖像信息，自主驅(qū)動(dòng)mobot。

機(jī)器人

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