创建订阅者代码（C++） * 该例程将订阅/turtle1/pose话题，消息类型turtlesim::Pose*/ #include #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 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; pose_subscriber.cpp ## 如何实现一个订阅者

tf坐标系广播与监听的编程实现 主讲人：古月 ## • 创建功能包 $ cd ~/catkin_ws/src $ catkin_create_pkg learning_tf roscpp rospy tf turtlesim 主目录 include  ros.h=""> #include #include <turtlesim pose.h=""> std::string turtle_name; void poseCallback(const turtlesim::PoseConstPtr& msg) ## // 创建tf的广播器 static tf::TransformBroadcaster subscribe(turtle_name + "/pose", 10, &poseCallback); ## // 循环等待回调函数 ros::spin(); ## 如何实现一个tf广播器 - 定义TF广播器（TransformBroadcaster） • 创建坐标变换值； - 发布坐标变换（sendTransform）turtlesim> ## • 创建tf监听器代码（C++）

rosrun turtlesim turtlesim_node $ rosrun turtlesim turtle_teleop_key  小海龟仿真器界面 hcx@hcx-vpc:~$ rosrun turtlesim turtlesim_node Starting turtlesim with node name /turtlesim [ INFO] [1561200736.954437402]: Spawning turtle [turtle1] at x=[5.544445], y=[5.544445], theta=[0.000000] 启动海龟仿真器节点 hcx@hcx-vpc:~$ rosrun turtlesim turtle_teleop_key [1562832989.611259134]: Subscribing to /rosout_agg [ INFO] [1562832989.614049029]: Subscribing to /turtle1/pose ^Chcx@hcx-vpc:~$ ^c hcx@hcx-vpc:~$ rosbag play cmd_record.bag [ INFO] [1562833040.748840302]: Opening

创建功能包 $ cd ~/catkin_ws/src $ catkin_create_pkg learning_topic roscpp rospy std_msgs geometry_msgs turtlesim CMakeLists.txt  编译并运行发布者 $ cd ~/catkin_ws $ catkin_make $ source devel/setup.bash $ roscore $ rosrun turtlesim turtlesim_node $ rosrun learning_topic velocity_publisher |hcX@hcX-VPC:~/catkin\_ws$ rosrun learning\_topic

std_msgs geometry_msgs turtlesim  ## • 创建客户端代码（C++） #include #include <turtlesim spawn.h=""> int main(int main(int argc, char** argv) // 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service ## // 初始化turtlesim::spawn的请求数据 turtlesim:: spawn sv; srv.request.x = 2.0; srv.request.y = 2.0; srv.request.name = "turtle2"; ## 如何实现一个客户端 turtle_spawn.cpp • 初始化ROS节点； • 创建一个Client实例； - 等待Server处理之后的应答结果。 • 发布服务请求数据;turtlesim> ## - 配置客户端代码编译规则 ## Declare a C++ executable ## With catkin_make all packages are built

machine> ## • Launch文件语法 ## launch simple.launch /launch> turtlesim_parameter_config.launch ## Launch示例

rosrun turtlesim turtlesim_node $ rosrun turtlesim turtle_teleop_key  小海龟仿真器界面 hcx@hcx-vpc:~$ rosrun turtlesim turtlesim_node Starting turtlesim with node name /turtlesim [ INFO] [1561200736.954437402]: Spawning turtle [turtle1] at x=[5.544445], y=[5.544445], theta=[0.000000] 启动海龟仿真器节点 hcx@hcx-vpc:~$ rosrun turtlesim turtle_teleop_key

${catkin_LIBRARYES}) CMakeLists.txt ## • 编译并运行发布者 $ catkin_make $ source devel/setup.bash $ rosrun turtlesim turtlesim_node $ rosrun learning_parameter_parameter_config hcx@hcx-vpc:~$ rosrun learning_parameter_parameter_config

编译并运行服务器 $ cd ~/catkin_ws $ catkin_make $ source devel/setup.bash $ roscore $ rosrun turtlesim turtlesim_node $ rosrun learning_service turtle_command_server $ rosservice call /turtle_command "{}"

apt-get install ros-melodic-turtle-tf $ roslaunch turtle_tf turtle_tf_demo.launch $ rosrun turtlesim turtle_teleop_key $ rosrun tf view_frames view_frames Result world Broadcaster: /turtle1_tf_broadcaster