Ubuntu 16.04
ros kinetic
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
来源官方文档: 传送门,点我点我
mkdir -p pubsub
cd pubsub
Publisher
vim talker.cpp
#include "ros/ros.h"
#include "std_msgs/String.h"
#include
/**
* 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;
}
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)
mkdir -p build
cd build
cmake ..
make
// 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
mkdir -p ~/catkin_ws/src # 创建工作区
cd ~/catkin_ws/src # 进入工作区
# catkin_create_pkg package_name(包名称) dependencies(依赖)
catkin_create_pkg my_node_demo roscpp std_msgs #新建一个ROS包, 包名:my_node_demo
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。
vim ~/catkin_ws/src/my_node_demo/src/publisher.cpp
#include
#include "std_msgs/String.h"
int main(int argc, char **argv) {
/*
void ros::init(
int &argc,
char **argv,
const std::string &name,
uint32_t options=0
)
argc:参数个数,一般由int main(int argc, char ** argv) 提供
argv:指向字符串数组(即参数文本)的指针,一般由int main(int argc, char ** argv) 提供
name:节点的名字,必须是基础的名字(基础的含义是不能包括命名空间)
options:可空,默认options=0
*/
ros::init(argc, argv, "publisher_demo"); // 初始化节点名
/*
NodeHandle类:
advertise():
Publisher ros::NodeHandle::advertise(
const std::string & topic,
uint32_t queue_size,
bool latch = false
)
ros::NodeHandle handle;
ros::Publisher pub = handle.advertise("my_topic", 1);
topic: 话题
queue_size: 队列大小
latch: 可空,默认为false; 如果为true,当有一个新的订阅者时,会向新的订阅者发送最后一条广播(在其订阅之前的最后一条)
*/
ros::NodeHandle handle;
ros::Publisher my_publisher_object = handle.advertise<std_msgs::String>("talker_demo",1);
std_msgs::String publish_msg; // 创建一个发布器将要使用的消息变量
/*
该消息定义在: /opt/ros/kinetic/share/std_msgs
在ROS中发布的消息都应该提前定义,以便订阅者接收到消息后该如何解读
Float64消息的定义如下,其中包含一个数据字段data:
float64 data
*/
publish_msg.data = "9";
while (ros::ok()){
// publish_msg.data = publish_msg.data + 0.001; //每循环一次+0.01
my_publisher_object.publish(publish_msg); // 发布消息到对应的话题
}
}
#include
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
vim ~/catkin_ws/src/my_node_demo/CMakeLists.txt
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})
cd ~/catkin_ws/
catkin_make
source /opt/ros/kinetic/setup.bash
source ~/catkin_ws/devel/setup.bash
roscore
// rosrun 包名 节点名
rosrun my_node_demo publisher_demo
订阅topic
// rostopic echo topic
rostopic echo talker_demo
vim ~/catkin_ws/src/my_node_demo/src/subscriber.cpp
#include "ros/ros.h"
#include "std_msgs/String.h"
// 接收到订阅的消息后,会进入消息回调函数
void chatter_callback(const std_msgs::String::ConstPtr& msg)
{
// 将接收到的消息打印出来
ROS_INFO("I heard: [%s]", msg->data.c_str());
}
int main(int argc, char **argv)
{
// 初始化ROS节点
ros::init(argc, argv, "listener_demo");
// 创建节点句柄
ros::NodeHandle handle;
// 创建一个Subscriber,订阅名为chatter的topic,注册回调函数chatterCallback
ros::Subscriber sub = handle.subscribe(
"talker_demo",
1000,
chatter_callback
);
// 循环等待回调函数
ros::spin();
return 0;
}
vim ~/catkin_ws/src/my_node_demo/CMakeLists.txt
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})
cd ~/catkin_ws/
catkin_make
新开一个terminal
source /opt/ros/kinetic/setup.bash
source ~/catkin_ws/devel/setup.bash
// rosrun 包名 节点名
rosrun my_node_demo subscriber_demo