ros2_不同ROS_DOMAIN_ID环境变量之间通信

1.需求

两台linux ros2系统设备, 配置了不同环境变量ROS_DOMAIN_ID,
期望在不同的ROS_DOMAIN_ID 之间, 进行话题通信.

2.解决方案调研

方案1: 第3方库 接受/转发消息

MQTT通信:
设备1或设备2: 安装MOTT broker
设备1: MQTT订阅消息
设备2: MQTT发布消息
设备1: 接受消息, 直接处理 或 转发为ros2 topic
socket tcp/udp 通信:
同mqtt, 自定义tcp/udp服务, 接受/转发消息

方案2: 确认 ros2 官网是否有相关解决方案

参考: https://wenku.csdn.net/doc/5e604uicy3
domain_bridge 跨ROS_DOMAIN_ID 发布消息
官网
github

方案确认:

参考官网实例, 使用domain_bridge, 能简单快速实现需求.
故使用 方案2: domain_bridge

3.domain_bridge 说明

ros2 domain bridge github 链接

domain_bridge 安装

sudo apt install ros-$ROS_DISTRO-domain-bridge

domain_bridge配置文件
example_bridge_config.yaml
: https://github.com/ros2/domain_bridge/blob/main/examples/example_bridge_config.yaml

name: my_bridge
from_domain: 1  # 源 domain
to_domain: 2    # 目的 domain
topics:
  topic: # 话题名
    type: std_msgs/msg/String # 消息类型

4.domain_bridge 使用示例

1.话题发布publish

1_topic_public.py

import rclpy
from rclpy.node import Node
from std_msgs.msg import String

class MinimalPublisher(Node):
    def __init__(self):
        super().__init__('minimal_publisher')
        self.publisher_ = self.create_publisher(String, 'topic', 10)
        timer_period = 0.5  # seconds
        self.timer = self.create_timer(timer_period, self.timer_callback)
        self.i = 0

    def timer_callback(self):
        msg = String()
        msg.data = 'Hello World: %d' % self.i
        self.publisher_.publish(msg)
        self.get_logger().info('Publishing: "%s"' % msg.data)
        self.i += 1

def main(args=None):
    rclpy.init(args=args)
    minimal_publisher = MinimalPublisher()
    rclpy.spin(minimal_publisher)
    minimal_publisher.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

2.订阅端subscribe

2_topic_subscriber.py

import rclpy
from rclpy.node import Node
from std_msgs.msg import String

class MinimalSubscriber(Node):
    def __init__(self):
        super().__init__('minimal_subscriber')
        self.subscription = self.create_subscription(String,'topic',self.listener_callback,10)
        self.subscription  # prevent unused variable warning

    def listener_callback(self, msg):
        self.get_logger().info('I heard: "%s"' % msg.data)

def main(args=None):
    rclpy.init(args=args)
    minimal_subscriber = MinimalSubscriber()
    rclpy.spin(minimal_subscriber)
    minimal_subscriber.destroy_node()
    rclpy.shutdown()

if __name__ == '__main__':
    main()

3.测试命令

终端设置不同的ROS_DOMAIN_ID环境变量, 进行通行

终端1:

export ROS_DOMAIN_ID=1
python3 1_topic_public.py

终端2:

export ROS_DOMAIN_ID=2
python3 2_topic_subscriber.py

此时 终端2 无法订阅到话题

终端3:

1.创建配置: example_bridge_config.yaml

# Name of the domain bridge, used for node naming and logging
name: my_bridge
from_domain: 1
to_domain: 2
topics:
  topic:
    type: std_msgs/msg/String

2.运行 domain_bridge
ros2 run domain_bridge domain_bridge example_bridge_config.yaml

此时会看到 终端2 能够订阅到话题

5.总结

1. 一开始向 抖音豆包, 腾讯元宝 需求解决方案, 给的全是错误答案, 根本不可行
2. 外网搜索, 匹配到关键字 domain_bridge , 才知道ros2 官方有跨ROS_DOMAIN_ID 通信解决方法

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