本文通过两种方式编译,一种是直接使用CMake,另一种是catkin_make
两种方式任选一种
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Publisher
vim talker.cpp #include "ros/ros.h" #include "std_msgs/String.h" #include <sstream> /** * This tutorial demonstrates simple sending of messages over the ROS system. */ int main(int argc, char **argv) { /** * The ros::init() function needs to see argc and argv so that it can perform * any ROS arguments and name remapping that were provided at the command line. * For programmatic remappings you can use a different version of init() which takes * remappings directly, but for most command-line programs, passing argc and argv is * the easiest way to do it. The third argument to init() is the name of the node. * * You must call one of the versions of ros::init() before using any other * part of the ROS system. */ ros::init(argc, argv, "talker"); /** * NodeHandle is the main access point to communications with the ROS system. * The first NodeHandle constructed will fully initialize this node, and the last * NodeHandle destructed will close down the node. */ ros::NodeHandle n; /** * The advertise() function is how you tell ROS that you want to * publish on a given topic name. This invokes a call to the ROS * master node, which keeps a registry of who is publishing and who * is subscribing. After this advertise() call is made, the master * node will notify anyone who is trying to subscribe to this topic name, * and they will in turn negotiate a peer-to-peer connection with this * node. advertise() returns a Publisher object which allows you to * publish messages on that topic through a call to publish(). Once * all copies of the returned Publisher object are destroyed, the topic * will be automatically unadvertised. * * The second parameter to advertise() is the size of the message queue * used for publishing messages. If messages are published more quickly * than we can send them, the number here specifies how many messages to * buffer up before throwing some away. */ ros::Publisher chatter_pub = n.advertise<std_msgs::String>("chatter", 1000); ros::Rate loop_rate(10); /** * A count of how many messages we have sent. This is used to create * a unique string for each message. */ int count = 0; while (ros::ok()) { /** * This is a message object. You stuff it with data, and then publish it. */ std_msgs::String msg; std::stringstream ss; ss << "hello world " << count; msg.data = ss.str(); ROS_INFO("%s", msg.data.c_str()); /** * The publish() function is how you send messages. The parameter * is the message object. The type of this object must agree with the type * given as a template parameter to the advertise<>() call, as was done * in the constructor above. */ chatter_pub.publish(msg); ros::spinOnce(); loop_rate.sleep(); ++count; } return 0; }Subscriber
vim listener.cpp #include "ros/ros.h" #include "std_msgs/String.h" /** * This tutorial demonstrates simple receipt of messages over the ROS system. */ void chatterCallback(const std_msgs::String::ConstPtr& msg) { ROS_INFO("I heard: [%s]", msg->data.c_str()); } int main(int argc, char **argv) { /** * The ros::init() function needs to see argc and argv so that it can perform * any ROS arguments and name remapping that were provided at the command line. * For programmatic remappings you can use a different version of init() which takes * remappings directly, but for most command-line programs, passing argc and argv is * the easiest way to do it. The third argument to init() is the name of the node. * * You must call one of the versions of ros::init() before using any other * part of the ROS system. */ ros::init(argc, argv, "listener"); /** * NodeHandle is the main access point to communications with the ROS system. * The first NodeHandle constructed will fully initialize this node, and the last * NodeHandle destructed will close down the node. */ ros::NodeHandle n; /** * The subscribe() call is how you tell ROS that you want to receive messages * on a given topic. This invokes a call to the ROS * master node, which keeps a registry of who is publishing and who * is subscribing. Messages are passed to a callback function, here * called chatterCallback. subscribe() returns a Subscriber object that you * must hold on to until you want to unsubscribe. When all copies of the Subscriber * object go out of scope, this callback will automatically be unsubscribed from * this topic. * * The second parameter to the subscribe() function is the size of the message * queue. If messages are arriving faster than they are being processed, this * is the number of messages that will be buffered up before beginning to throw * away the oldest ones. */ ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback); /** * ros::spin() will enter a loop, pumping callbacks. With this version, all * callbacks will be called from within this thread (the main one). ros::spin() * will exit when Ctrl-C is pressed, or the node is shutdown by the master. */ ros::spin(); return 0; } 编写CMake代码 vim CMakeLists.txt cmake_minimum_required(VERSION 2.8.3) project(myproject) # Build the talker and listener. Each one uses the following ROS packages, # which we need to find_package() individually: # roscpp (the client library) # std_msgs (contains the std_msgs/String message type) find_package(roscpp REQUIRED) find_package(std_msgs REQUIRED) # We've found them; now use their variables in the usual way to configure # the compile and link steps. # Note: we skip calling link_directories() because ROS packages follow the # recommended CMake practice of returning absolute paths to libraries include_directories(${roscpp_INCLUDE_DIRS}) include_directories(${std_msgs_INCLUDE_DIRS}) add_executable(talker talker.cpp) target_link_libraries(talker ${roscpp_LIBRARIES} ${std_msgs_LIBRARIES}) add_executable(listener listener.cpp) target_link_libraries(listener ${roscpp_LIBRARIES} ${std_msgs_LIBRARIES}) # (optional) Install the executables. install(TARGETS talker listener DESTINATION bin) 编译 mkdir -p build cd build cmake .. make 运行 // 新开窗口 roscore ./build/talker ./build/listener通过CMake方式编译,到此完成,生成两个二进制可执行文件
创建完成以后,在目录my_node_demo下多出两个文件(package.xml ,CMakeLists.txt)和两个文件夹(src, include)。
其中的package.xml便是之前提到的ROS包配置文件，描述关于包的信息。CMakeLists.txt是用来配置编译过程。
#include <ros/ros.h>表示包含ROS头文件
#include "std_msgs/String.h"表示包含标准消息类型中的String
在最后加上下面两行代码:
add_executable(publisher_demo src/publisher.cpp) target_link_libraries(publisher_demo ${catkin_LIBRARIES})订阅topic
// rostopic echo topic rostopic echo talker_demo在最后加上下面两行代码:
add_executable(publisher_demo src/publisher.cpp) add_executable(subscriber_demo src/subscriber.cpp) target_link_libraries(publisher_demo ${catkin_LIBRARIES}) target_link_libraries(subscriber_demo ${catkin_LIBRARIES})新开一个terminal
source /opt/ros/kinetic/setup.bash source ~/catkin_ws/devel/setup.bash 运行subscriber // rosrun 包名 节点名 rosrun my_node_demo subscriber_demo