一、話題(Topic)通訊簡介
二、話題案例
2.1、新建功能包
cd ~/ros_ws/src ros2 pkg create pkg_topic --build-type ament_python --dependencies rclpy --node-name publisher_demo
2.2、發佈者實現
# 導入rclpy import rclpy from rclpy.node import Node # 導入String字符串消息 from std_msgs.msg import String class Topic_Publisher(Node): def __init__(self, name): super().__init__(name) # 創建發佈者,使用create_publisher函數 # 傳入參數分別是:話題數據類型、話題名稱、消息隊列長度 self.pub = self.create_publisher(String, "/topic_demo", 1) # 中斷函數執行的間隔時間,中斷處理函數 self.timer = self.create_timer(1, self.pub_msg) # 定義處理函數 def pub_msg(self): msg = String() msg.data = "Hello, I send a message" self.pub.publish(msg) #發佈話題數據 def main(): rclpy.init() publisher_demo = Topic_Publisher("publisher_node") rclpy.spin(publisher_demo) publisher_demo.destroy_node() rclpy.shutdown()
2.3、訂閱方實現
# 導入相關的庫 import rclpy from rclpy.node import Node from std_msgs.msg import String class Topic_Subscriber(Node): def __init__(self, name): super().__init__(name) # 創建訂閱者使用的是create_subscription # 參數分別是:話題數據類型、話題名稱、回調函數名稱,隊列長度 self.sub = self.create_subscription(String, "/topic_demo", self.sub_callback, 1) # 回調函數 def sub_callback(self, msg): print("recv:" + msg.data) def main(): rclpy.init() subscriber_demo = Topic_Subscriber("subscriber_node") rclpy.spin(subscriber_demo) subscriber_demo.destroy_node() rclpy.shutdown()
2.4、編輯配置文件、編譯工作空間
編譯工作空間
cd ~/ros_ws colcon build --packages-select pkg_topic source install/setup.bash
2.5、運行程序
# 啓動發佈者節點 ros2 run pkg_topic publisher_demo # 啓動訂閱者節點 ros2 run pkg_topic subscriber_demo
運行發佈者節點
運行訂閱者節點