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------ROS学习记录-----古月居ROS21讲----1-14讲
1.roscore
2.rosrun turtlesim turtlesim_node
3.rosrun turtlesim turtle_teleop_key
4.rqt_graph
5.rosnode list
6.rosnode info /turtlesim
7.rostopic pub /turtle1/cmd_vel TAB键
8.rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twist "linear: x: 8.0 y: 2.0 z: 0.0 angular: x: 0.0 y: 0.0 z: 0.0"
9.rosmsg show geometry_msgs/Twist
10.rosservice list
11.rosservice call /spawn "x:1.0 y:1.0 theta: 10.0 name: ''"
12. rosbag record -a -o cmd_record(默认保存在Home)
13.rosbag play cmd_record_2020-08-21-10-36-45.bag （先1再2）
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1.创建工作空间
$ mkdir -p ~/catkin_ws/src
$ cd ~/catkin_ws/src
$ src下：catkin_init_workspace src文件夹中会出现cmakelists文件，表示已经成为一个ROS包文件
2.编译工作空间
$ cd ~/catkin_ws/
$ catkin_make或者catkin_make install(出现install文件夹-开发后文件)，devel文件夹存放开发过程中产生的文件，库。build文件夹中是存放编译过程中的中间文件。
3.设置环境变量
$ source devel/setup.bash
4.检查环境变量
$ echo $ROS_PACKAGE_PATH
5.创建功能包：
$ cd ~/catkin_ws/src
$ catkin_create_pkg test_pkg std_msgs rospy roscpp
6.编译功能包：
$ cd ~/catkin_ws
$ catkin_make
$ source ~/catkin_ws/devel/setup.bash
!!!同一个工作空间下，不允许存在同名功能包！不同工作空间下，允许存在同名功能包。
package.xml: 存放功能包基本信息及依赖信息
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发布者publisher的编程实现：（我们发布，turtlesim接收）
1.创建功能包：
$ cd catkin_ws/src
$ catkin_create_pkg learning_topic std_msgs roscpp rospy geometry_msgs turtlesim
2.编写代码
$ cd learning_topic/src
$ touch velocity_publisher.cpp
$ sudo gedit velocity_publisher.cpp
如下代码：
/*
*该例程将发布turtle1/cmd_vel话题，消息类型geometry_msgs::Twist
*/
#include<ros/ros.h>
#include<geometry_msgs/Twist.h>
int main(int argc,char **argv)
{
//ROS节点初始化
ros::init(argc,argv,"velocity_publisher");//节点名字：velocity_publisher
//创建节点句柄
ros::Nodehandle n;
//创建一个publisher，发布名为turtle1/cmd_vel的topic，消息类型为geometry_msgs：：Twist，队列长度为10
ros::Publisher turtle_vel_pub =n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel",10);//<>里面是消息类型,()里是往哪个话题发布消息
//设置循环的频率
ros::Rate loop_rate(10);
int count = 0;
while(ros::ok())
{
//初始化geometry_msgs::Twist类型的消息
geometry_msgs::Twist vel_msg;
vel_msg.linear.x = 0.5;
vel_msg.angular.z = 0.2;
//发布消息
turtle_vel_pub.publish(vel_msg);
ROS_INFO("Publish turtle velocity command[%0.2f m/s,%0.2f rad/s]",vel_msg.linear.x,vel_msg.angular.z);
//按照循环频率延时
loop_rate.sleep();
}
return 0;
}
-------------------------------
总结：如何实现一个发布者
1.初始化ROS节点
2.向ROS Master注册节点信息，包括发布的话题名和话题中的消息类型
3.创建消息数据
4.按照一定频率循环发布消息
------------------------------
修改CMakelists文件
1.$ cd catkin_ws/src/learning_topic
2.$ gedit CMakeLists.txt
3.
add_executable(velocity_publisher src/velocity_publisher.cpp)
target_link_libraries(velocity_publisher ${catkin_LIBRARIES})
----------编译--------
1.$ cd catkin_ws
2.$ catkin_make
3.$ source devel/setup.bash
(或者直接在终端 $ sudo gedit ~/.bashrc 最下面增加一行：source ~/catkin_ws/devel/setup.bash)
(4 5 6需要在3个不同的终端运行)
4.$ roscore
5.$ rosrun turtlesim turtlesim_node
6.$ rosrun learning_topic velocity_publisher
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订阅者的编程实现(turtlesim发布，我们接收)
1.$ cd catkin_ws/src/learning_topic/src
2.$ touch pose_subscriber.cpp
3.代码：
/*
*该例程将订阅/turtle1/pose话题，消息类型turtlesim::Pose
*/
#include<ros/ros.h>
#include"turtlesim/Pose.h"
//接收到订阅的消息后，会进入消息回调函数
void poseCallback(const turtlesim::Pose::ConstPtr& msg)
{
//将接收到的消息打印出来
ROS_INFO("Turtle pose: x:%0.6f,y:%0.6f",msg->x,msg->y);
}
int main(int argc,char **argv)
{
//初始化ROS节点
ros::init(argc,argv,"pose_subscriber");
//创建句柄节点
ros::NodeHandle n;
//创建一个subscriber，订阅名为turtle1//pose的topic，注册回调函数poseCallback
ros::Subscriber pose_sub = n.subscribe("turtle1//pose",10,poseCallback);
//循环等待回调函数
ros::spin();
return 0;
}
-----------------
总结 如何实现一个订阅者
1.初始化ROS节点
2.订阅需要的话题
3.循环等待话题消息，接收到消息后进入回调函数
4.在回调函数中完成消息处理
----------修改CMakeLists文件
增加：
add_executable(pose_subscriber src/pose_subscriber.cpp)
target_link_libraries(pose_subscriber ${catkin_LIBRARIES})
---------------编译
1.$ cd catkin_ws
2.$ catkin_make
3.$ source devel/setup.bash
4.$ roscore
5.$ rosrun turtlesim turtlesim_node
6.$ rosrun learning_topic velocity_publisher
7.$ rosrun learning_topic pose_subscriber
(看到终端实时输出小海龟的位置信息，是接收到上面publisher发布的做圆周运动的信息)
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话题消息的订阅与使用 自定义
----定义msg文件
1.$ cd catkin_ws/src/learning_topic
2.$ mkdir msg
3.$ cd msg
4.$ touch Person.msg
里面内容：
string name
uint8 sex
uint8 age
uint8 unknown = 0
uint8 male = 1
uint8 female = 2
完成数据接口的定义
--------在package.xml中添加功能包依赖
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>
---------在CMakelists中添加编译选项
add_message_files(FILES Person.msg)
generate_messages(DEPENDENCIES std_msgs)----依赖std_msgs,像uint8都是std_msgs里面的
然后找到catkin_packages(...)这句话，变成这样：
catkin_packages（CATKIN_DEPENDS geometry_msgs roscpp rospy std_msgs turtlesim message_runtime）
然后找到find_package(...)这句话，括号前加message_generation
-----------编译
1.$ cd catkin_ws
2.$ catkin_make
-----------------
1.$ cd catkin_ws/src/learning_topic/src
2.$ touch persion_publisher.cpp
3.$ gedit persion_publisher.cpp
代码内容：
/**
* 该例程将发布/person_info话题，自定义消息类型learning_topic::Person
*/
#include <ros/ros.h>
//！！！！！关键！！！！！
#include "learning_topic/Person.h"
int main(int argc, char **argv)
{
// ROS节点初始化
ros::init(argc, argv, "person_publisher");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个Publisher，发布名为/person_info的topic，消息类型为learning_topic::Person，队列长度10
//！！！！！关键！！！！！
ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);
// 设置循环的频率
ros::Rate loop_rate(1);
int count = 0;
while (ros::ok())
{
// 初始化learning_topic::Person类型的消息
learning_topic::Person person_msg;
person_msg.name = "Tom";
person_msg.age = 18;
person_msg.sex = learning_topic::Person::male;
// 发布消息
person_info_pub.publish(person_msg);
ROS_INFO("Publish Person Info: name:%s age:%d sex:%d",
person_msg.name.c_str(), person_msg.age, person_msg.sex);
// 按照循环频率延时
loop_rate.sleep();
}
return 0;
}
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4.$ touch persion_subscriber.cpp
5.$ gedit persion_subscriber.cpp
代码为：
/**
* 该例程将订阅/person_info话题，自定义消息类型learning_topic::Person
*/
#include <ros/ros.h>
//！！！！！关键！！！！！
#include "learning_topic/Person.h"
// 接收到订阅的消息后，会进入消息回调函数
void personInfoCallback(const learning_topic::Person::ConstPtr& msg)
{
// 将接收到的消息打印出来
ROS_INFO("Subcribe Person Info: name:%s age:%d sex:%d",
msg->name.c_str(), msg->age, msg->sex);
}
int main(int argc, char **argv)
{
// 初始化ROS节点
ros::init(argc, argv, "person_subscriber");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个Subscriber，订阅名为/person_info的topic，注册回调函数personInfoCallback
//！！！！！关键！！！！！
ros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);
// 循环等待回调函数
ros::spin();
return 0;
}
--------------------------------------------
CMakelists文件增加：
add_executable(person_publisher src/person_publisher.cpp)
target_link_libraries(person_publisher ${catkin_LIBRARIES})
add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)
add_executable(person_subscriber src/person_subscriber.cpp)
target_link_libraries(person_subscriber ${catkin_LIBRARIES})
add_dependencies(person_subscriber ${PROJECT_NAME}_generate_messages_cpp)
-------------编译
$ cd catkin_ws
$ catkin_make
$ rosocre
$ rosrun learning_topic person_publisher
$ rosrun learning_topic person_subscriber
可以看到发布者和订阅者之间的数据传输没有问题。
思考：传输过程中 把roscore（也就是ros-master）关掉会影响传输吗？ 不会 相当于婚姻介绍所，介绍结束就完事了。
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客户端Client的编程实现
创建功能包
1.$ cd ~/.catkin_ws/src
2.$ catkin_create_pkg learning_service roscpp rospy std_msgs geometry_msgs turtlesim
3.$ cd learning_service/src
4.$ touch turtle_spawn.cpp
5.$ gedit turtle_spawn.cpp
代码内容复制：
/**
* 该例程将请求/spawn服务，服务数据类型turtlesim::Spawn
*/
#include <ros/ros.h>
#include <turtlesim/Spawn.h>
int main(int argc, char** argv)
{
// 初始化ROS节点
ros::init(argc, argv, "turtle_spawn");
// 创建节点句柄
ros::NodeHandle node;
// 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
ros::service::waitForService("/spawn");
ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("/spawn");
// 初始化turtlesim::Spawn的请求数据
turtlesim::Spawn srv;
srv.request.x = 2.0;
srv.request.y = 2.0;
srv.request.name = "turtle2";
// 请求服务调用
ROS_INFO("Call service to spwan turtle[x:%0.6f, y:%0.6f, name:%s]",
srv.request.x, srv.request.y, srv.request.name.c_str());
add_turtle.call(srv);
// 显示服务调用结果
ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str());
return 0;
};
--------配置CMakelists文件
add_executable(turtle_spawn src/turtle_spawn.cpp)
target_link_libraries(turtle_spawn ${catkin_LIBRARIES})
-----------编译
$ cd catkin_ws
$ catkin_make
-----------运行
$ roscore
$ rosrun turtlesim turtlesim_node
$ rosrun learning_serrvice turtle_spawn
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服务端server的编程实现
1.$ cd catkin_ws/src/learning_service/src
2.$ touch turtle_command_server.cpp
3.$ gedit turtle_command_server.cpp
代码内容为：
/**
* 该例程将执行/turtle_command服务，服务数据类型std_srvs/Trigger
*/
#include <ros/ros.h>
#include <geometry_msgs/Twist.h>
#include <std_srvs/Trigger.h>
ros::Publisher turtle_vel_pub;
bool pubCommand = false;
// service回调函数，输入参数req，输出参数res
bool commandCallback(std_srvs::Trigger::Request &req,
std_srvs::Trigger::Response &res)
{
pubCommand = !pubCommand;
// 显示请求数据
ROS_INFO("Publish turtle velocity command [%s]", pubCommand==true?"Yes":"No");
// 设置反馈数据
res.success = true;
res.message = "Change turtle command state!";
return true;
}
int main(int argc, char **argv)
{
// ROS节点初始化
ros::init(argc, argv, "turtle_command_server");
// 创建节点句柄
ros::NodeHandle n;
// 创建一个名为/turtle_command的server，注册回调函数commandCallback
ros::ServiceServer command_service = n.advertiseService("/turtle_command", commandCallback);
// 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10
turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10);
// 循环等待回调函数
ROS_INFO("Ready to receive turtle command.");
// 设置循环的频率
ros::Rate loop_rate(10);
while(ros::ok())
{
// 查看一次回调函数队列
ros::spinOnce();
// 如果标志为true，则发布速度指令
if(pubCommand)
{
geometry_msgs::Twist vel_msg;
vel_msg.linear.x = 0.5;
vel_msg.angular.z = 0.2;
turtle_vel_pub.publish(vel_msg);
}
//按照循环频率延时
loop_rate.sleep();
}
return 0;
}
--------------------------
修改CMakelists文件 增加代码：
add_executable(turtle_command_server src/turtle_command_server.cpp);
target_link_libraries(turtle_command_server ${catkin_LIBRARIES});
--------------编译---
1. $ cd ~/catkin_ws
2. $ catkin_make
3. $ source devel/setup.bash
4. $ roscore
5. $ rosrun turtlesim turtlesim_node
6. $ rosrun learning_service turtle_command_server
7. $ rosservice call /turtle_command "{}"
可以看到小乌龟在圆周运动，再次运行7命令发现小海龟停止运动，相当于客户端是一个开关。
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未完，待续...
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