ROS话题通信

容易出错的地方

链接catkin的库

target_link_libraries(main ${catkin_LIBRARIES})

使用自定义头文件，前面加包名

#include "package_name/xxx.h"

CMakeLists.txt

如果有自定义类，需要包含头文件和链接库

// 头文件位置
include_libraries(include)

// 添加库文件
add_libraries(Student STATIC src/Student.cpp)

// 链接
target_link_libraries(main Student)

std_msgs的数据类型

#include <std_msgs/Float64.h>
float64 data

#include <std_msgs/Float64MultiArray.h>
float64[] data  // 这种可变数组就相当于vector

代码示例

发布者 talker

int main(int argc, char** argv)
{
    ros::init(argc, argv, "talker");    // 节点名
    ros::NodeHandle n;                  // 句柄
    ros::Publisher pub = n.advertise<std_msgs::Float64>("chatting", 10);
    // 往chatting话题上发消息，数据类型是std_msgs::Float64
    std_msgs::Float64 input;
    input.data = 0.0;
    ros::Rate loop_rate(1);     // 1s发一次
    while(ros::ok())
    {
        input.data += 0.1;
        pub.publish(input);
        loop_rate.sleep();
    }
}

不同数据类型std_msgs::Float64MultiArray

int main(int argc, char** argv)
{
    ros::init(argc, argv, "talker");
    ros::NodeHandle n;
    ros::Publisher pub = n.advertise<std_msgs::Float64MultiArray>("chatting", 10);
    ros::Rate loop_rate(1);
    double arr[3] = {14, 15, 16};
    std::vector<double> vi(arr, arr+3);     // float64就是double
    std_msgs::Float64MultiArray input_float;
    input_float.data = vi;
    while(ros::ok())
    {
        for (auto& i : input_float.data)
            std::cout << i << " ";
        std::cout << std::endl;
        pub.publish(input_float);
        loop_rate.sleep();
    }
}

订阅者 listener

void chatting_cb(const std_msgs::Float64::ConstPtr& message)
{
    ROS_INFO("I receive the number: %f", message->data);
}
int main(int argc, char** argv)
{
    ros::init(argc, argv, "listener");
    ros::NodeHandle n;
    ros::Subscribe sub = n.subscribe("chatting", 1, chatting_cb);
    ros::spin();    // 阻塞
}

CMakeLists.txt

cmake_minimum_required(VERSION 3.0.2)
project(learning_communication)

find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
)

catkin_package()

include_directories(
  include
  ${catkin_INCLUDE_DIRS}
)

add_executable(talker src/talker.cpp)

target_link_libraries(talker ${catkin_LIBRARIES})

Python

发布者

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import rospy
from std_msgs.msg import String
from test_msgs.msg import Position


def talker():
    rospy.init_node('py_talker', anonymous=True)
    Pos_pub = rospy.Publisher('/test/Position', Position, queue_size=10)
    rate = rospy.Rate(10)
    pos = Position()
    pos.x = 10
    pos.y = 20
    while not rospy.is_shutdown():
        pos.x += 1
        pos.y += 2
        rospy.loginfo(pos)
        Pos_pub.publish(pos)
        rate.sleep()


if __name__ == '__main__':
    try:
        talker()
    except rospy.ROSInterruptException:pass

订阅者

#! /usr/bin/env python
# -*- coding: utf-8 -*-

import rospy
from test_msgs.msg import Position

def callback(msg):
    rospy.loginfo('Receive: %f, %f', msg.x, msg.y)

def listener():
    rospy.init_node('py_listener', anonymous=True)
    rospy.Subscriber('/test/Position', Position, callback)
    rospy.spin()

if __name__ == '__main__':
    try:
        listener()
    except rospy.ROSInitException:pass