目录
一、基础知识
二、工作空间与功能包
三、发布者的编程实现
四、订阅者的编程实现
// 功能包名 功能包中的某一个节点 $rosrun turtlesim turtlesim_node
// 1秒钟10次(频率) 话题名 消息数据类型 $rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twist "消息结构具体数据" ros里速度单位为m/s,角速度单位rad/s
//终端可以作为客户端去请求某个服务 $rosservice list //发布服务请求 $rosservice call/spawn "服务内容"
$rosnode list //查看所有话题节点,注:/rosout这个ros默认的话题 $rosnode info /turtlesim //查看某个节点的具体信息,如发布的哪些话题,订阅了哪些话题。
//话题记录 $rosbag record -a -O cmd_record //话题复现 $rosbag play cmd_record.bag
工作空间:
1.创建工作空间
$mkdir -p ~/catkin_ws/src $cd ~/catkin/src $catkin_init_workspace
2.编译工作空间
$cd ~/catkin_ws/ $catkin_make //在生成install安装空间 $catkin_make install
3.设置环境变量
$source devel/setup.bash
4.检查环境变量
$echo $ROS_PACKAGE_PATH
功能包:
注意:功能包是放置源码的最小单元,不能直接将源码放置src中。
1.创建功能包
$cd ~/catkin_ws/src $catkin_create_pkg test_pkg std_msgs rospy roscpp
2.编译功能包
$cd ~/catkin_ws $catkin_make $source ~/catkin_ws/devel/setup.bash
1、创建功能包
$cd ~/catkin_ws/src $catkin_create_pkg learning_topic rosscpp rospy std_msgs geometry_msgs turtlesim
2、创建发布者
将编写好的发布者的源码放置在~/catkin_ws/src/learning_topic/src
velocity_publisher.cpp
#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"); // 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10 ros::Publisher turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10); // 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("Publsh 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; }
编写编译规则
CMakeLists.txt ######### ##build## ######### add_executable(velocity_publisher src/velocity_publisher.cpp) target_link_libraries(velocity_publisher ${catkin_LIBRARIES})
编译并运行发布者
$cd ~/catkin_ws $catkin_make //执行程序前一定要设置环境变量 $source devel/setup.bash $roscore $rosrun turtlesim turtlesim_node $rosrun learning_topic velocity_publisher
1、实现订阅者
pose_subscriber.cpp
/** * 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"); // 创建节点句柄 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; }
编写编译规则
CMakeLists.txt ######### ##build## ######### add_executable(pose_subscriber src/pose_subscriber.cpp) target_link_libraries(pose_subscriber ${catkin_LIBRARIES})
编译并运行发布者
$cd ~/catkin_ws $catkin_make //执行程序前一定要设置环境变量 $source devel/setup.bash $roscore $rosrun turtlesim turtlesim_node $rosrun learning_topic pose_subscriber