在ROS 2(Robot Operating System 2)中,節點之間的通信主要通過話題(Topics)、服務(Services)和動作(Actions)來實現。下面是一個簡單的C++ ROS 2節點通信示例,包括一個發布者(Publisher)和一個訂閱者(Subscriber)。
首先,確保你已經安裝了ROS 2和相應的開發工具。
創建一個新的ROS 2工作空間和包:
mkdir -p ~/ros2_ws/src
cd ~/ros2_ws/src
colcon build --symlink-install
source install/setup.bash
package.xml
文件中添加以下內容,以創建一個名為my_package
的包,其中包含一個發布者(Publisher)和一個訂閱者(Subscriber):<package name="my_package" version="0.0.0">
<description>My ROS 2 package with publisher and subscriber</description>
<license>Apache License 2.0</license>
<authors>
<author email="user@example.com">Your Name</author>
</authors>
<build_type>ament_cmake</build_type>
<dependencies>
<dependency>rclcpp</dependency>
<dependency>std_msgs</dependency>
</dependencies>
</package>
創建一個名為my_package/src
的文件夾,并在其中創建兩個C++源文件:publisher.cpp
和subscriber.cpp
。
在publisher.cpp
文件中,編寫一個發布者節點,用于發布名為my_topic
的話題:
#include <iostream>
#include <memory>
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
class Publisher : public rclcpp::Node {
public:
Publisher() : Node("publisher") {
publisher_ = this->create_publisher<std_msgs::msg::String>("my_topic", 10);
timer_ = this->create_wall_timer(1000ms, std::bind(&Publisher::publish_message, this));
}
private:
void publish_message() {
auto message = std_msgs::msg::String();
message.data = "Hello, ROS 2!";
publisher_->publish(message);
RCLCPP_INFO(this->get_logger(), "Published: '%s'", message.data.c_str());
}
std::shared_ptr<rclcpp::Publisher<std_msgs::msg::String>> publisher_;
std::shared_ptr<rclcpp::TimerBase> timer_;
};
int main(int argc, char *argv[]) {
rclcpp::init(argc, argv);
rclcpp::spin(std::make_shared<Publisher>());
rclcpp::shutdown();
return 0;
}
subscriber.cpp
文件中,編寫一個訂閱者節點,用于訂閱名為my_topic
的話題:#include <iostream>
#include <memory>
#include "rclcpp/rclcpp.hpp"
#include "std_msgs/msg/string.hpp"
class Subscriber : public rclcpp::Node {
public:
Subscriber() : Node("subscriber") {
subscription_ = this->create_subscription<std_msgs::msg::String>("my_topic", 10, std::bind(&Subscriber::callback, this, std::placeholders::_1));
}
private:
void callback(const std_msgs::msg::String::SharedPtr msg) {
RCLCPP_INFO(this->get_logger(), "Received: '%s'", msg->data.c_str());
}
std::shared_ptr<rclcpp::Subscription<std_msgs::msg::String>> subscription_;
};
int main(int argc, char *argv[]) {
rclcpp::init(argc, argv);
rclcpp::spin(std::make_shared<Subscriber>());
rclcpp::shutdown();
return 0;
}
my_package
文件夾中創建一個名為CMakeLists.txt
的文件,用于編譯源文件:cmake_minimum_required(VERSION 3.5)
project(my_package)
find_package(ament_cmake REQUIRED)
find_package(rclcpp REQUIRED)
find_package(std_msgs REQUIRED)
add_executable(publisher src/publisher.cpp)
add_executable(subscriber src/subscriber.cpp)
ament_target_dependencies(publisher rclcpp std_msgs)
ament_target_dependencies(subscriber rclcpp std_msgs)
install(TARGETS publisher subscriber LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION})
cd ~/ros2_ws
colcon build --symlink-install
source install/setup.bash
ros2 run my_package publisher
ros2 run my_package subscriber
現在,你應該能看到發布者在每隔1秒發布一條消息,而訂閱者則接收并打印這些消息。這就是一個簡單的C++ ROS 2節點通信示例。你可以根據需要擴展此示例,以實現更復雜的消息傳遞和處理邏輯。