ros中地面站和无人机跨平台数据传递，使用 UDP 进行跨平台传输（python代码）

核心流程： 地面站订阅 ground_data_topic 话题 → 收到 ROS 消息 → 序列化为 UDP 数据包 → 通过 UDP
发送给无人机

1.数据介绍

1.1 自定义数据类型

1_GroundObject.msg 文件的内容应为：

float64 UTC_time  # in ms
int32 VehicleNumber
VEHICLE_OBJ_COOP[] VehicleObjectCOOP

VEHICLE_OBJ_COOP.msg 文件的内容应为：

int32 class  # 0:unknown 1:car 2:pedestrian
int32 ismove
int32 vehicleclass  # 0:HM 1:LM 3:objects
float64 lon  # longitude
float64 lat  # latitude

1.2 文件夹结构

your_ros_workspace/
├── src/
│   ├── your_package/
│   │   ├── msg/
│   │   │   ├── 1_GroundObject.msg
│   │   │   ├── VEHICLE_OBJ_COOP.msg
│   │   ├── src/
│   │   │   ├── ground_udp_publisher.py
│   │   │   ├── ground_udp_subscriber.py
│   │   ├── CMakeLists.txt
│   │   ├── package.xml

1.3 CMakeLists.txt修改

在 CMakeLists.txt 中，需要确保自定义消息的生成和依赖性已经添加。

cmake_minimum_required(VERSION 3.0.2)
project(your_package)

find_package(catkin REQUIRED COMPONENTS
  rospy
  std_msgs
  message_generation
)

add_message_files(
  FILES
  1_GroundObject.msg
  VEHICLE_OBJ_COOP.msg
)

generate_messages(
  DEPENDENCIES
  std_msgs
)

catkin_package(
  CATKIN_DEPENDS message_runtime std_msgs
)

include_directories(
  ${catkin_INCLUDE_DIRS}
)

1.4 package.xml

在 package.xml 中，添加对 message_generation 和 message_runtime 的依赖：

<package format="2">
  <name>your_package</name>
  <version>0.0.0</version>
  <description>UDP communication between vehicle and drone</description>

  <maintainer email="your_email@example.com">Your Name</maintainer>

  <license>BSD</license>

  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>message_generation</build_depend>
  <build_depend>rospy</build_depend>

  <exec_depend>message_runtime</exec_depend>
  <exec_depend>rospy</exec_depend>
</package>

2.UDP 发送代码（ground_udp_publisher.py）

#!/usr/bin/env python
import rospy
import socket
from your_package.msg import 1_GroundObject, VEHICLE_OBJ_COOP

# 创建 UDP socket
udp_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_ip = "无人机的IP地址"  # 目标无人机的IP
udp_port = 12345  # 目标无人机的端口号

def send_udp_message(msg):
    # 将自定义消息序列化并发送
    data = f"{msg.UTC_time},{msg.VehicleNumber}," + ",".join([f"{obj.class},{obj.ismove},{obj.vehicleclass},{obj.lon},{obj.lat}" for obj in msg.VehicleObjectCOOP])
    udp_sock.sendto(data.encode(), (udp_ip, udp_port))

def ros_to_udp():
    rospy.init_node('ground_udp_publisher')
    rospy.Subscriber("ground_data_topic", 1_GroundObject, send_udp_message)  # 订阅 ROS 话题
    rospy.spin()

if __name__ == '__main__':
    try:
        ros_to_udp()
    except rospy.ROSInterruptException:
        pass
    finally:
        udp_sock.close()

2.1代码解释

socket：Python 的网络通信库，提供了 UDP 和 TCP 的接口。

#创建一个 UDP socket。AF_INET 指的是 IPv4 协议，SOCK_DGRAM 指的是 UDP 协议。
socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

“,”.join([…])：遍历 msg.VehicleObjectCOOP 数组中的每个对象，将每个对象的属性（class, ismove, vehicleclass, lon, lat）提取出来，构成一个逗号分隔的字符串。

#将序列化后的字符串 data 编码为字节，并通过 sendto 函数发送到 udp_ip 和 udp_port 指定的无人机地址。
udp_sock.sendto(data.encode(), (udp_ip, udp_port))

#订阅 ROS 话题 ground_data_topic，当收到消息时，调用 send_udp_message 函数。该函数会将收到的 ROS 消息通过 UDP 发送出去。
rospy.Subscriber("ground_data_topic", 1_GroundObject, send_udp_message)

3.UDP 接受代码（ground_udp_subscriber.py）

#!/usr/bin/env python
import rospy
import socket
from your_package.msg import 1_GroundObject, VEHICLE_OBJ_COOP

# 创建 UDP socket
udp_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_ip = "0.0.0.0"  # 本地IP
udp_port = 12345  # 本地监听端口
udp_sock.bind((udp_ip, udp_port))

def udp_to_ros():
    rospy.init_node('ground_udp_subscriber')
    pub = rospy.Publisher('ground_data_topic', 1_GroundObject, queue_size=10)
    
    while not rospy.is_shutdown():
        data, addr = udp_sock.recvfrom(1024)
        decoded_data = data.decode().split(',')
        obj = 1_GroundObject()
        obj.UTC_time = float(decoded_data[0])
        obj.VehicleNumber = int(decoded_data[1])
        for i in range(2, len(decoded_data), 5):
            vehicle_obj = VEHICLE_OBJ_COOP()
            vehicle_obj.class = int(decoded_data[i])
            vehicle_obj.ismove = int(decoded_data[i+1])
            vehicle_obj.vehicleclass = int(decoded_data[i+2])
            vehicle_obj.lon = float(decoded_data[i+3])
            vehicle_obj.lat = float(decoded_data[i+4])
            obj.VehicleObjectCOOP.append(vehicle_obj)
        
        pub.publish(obj)

if __name__ == '__main__':
    try:
        udp_to_ros()
    except rospy.ROSInterruptException:
        pass
    finally:
        udp_sock.close()

4.编译和运行

cd ~/your_ros_workspace
catkin_make

编译成功后，使用以下命令使环境变量生效：

source devel/setup.bash

4.2 启动 ROS 节点（启动无人车和无人机的 UDP 发布和订阅节点。）

在无人机端启动发布节点

rosrun your_package ground_udp_publisher.py

在无人车启动接受节点

rosrun your_package ground_udp_subscriber.py

这样，无人车上的 ROS 信息将通过 UDP 协议发送到无人机，无人机再将这些信息发布为 ROS 话题，进行进一步的处理。

5.数据生成与udp格式发布（合为一个节点的示例）

algorithm_and_udp_node.py

#!/usr/bin/env python
import rospy
import socket
from your_package.msg import 1_GroundObject, VEHICLE_OBJ_COOP

# 创建 UDP socket
udp_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp_ip = "无人机的IP地址"  # 目标无人机的IP
udp_port = 12345  # 目标无人机的端口号

def send_udp_message(msg):
    # 将自定义消息序列化并发送
    data = f"{msg.UTC_time},{msg.VehicleNumber}," + ",".join([f"{obj.class},{obj.ismove},{obj.vehicleclass},{obj.lon},{obj.lat}" for obj in msg.VehicleObjectCOOP])
    udp_sock.sendto(data.encode(), (udp_ip, udp_port))

def algorithm_publish():
    pub = rospy.Publisher('ground_data_topic', 1_GroundObject, queue_size=10)
    rospy.Subscriber("ground_data_topic", 1_GroundObject, send_udp_message)  # 订阅并发送数据
    rospy.init_node('algorithm_and_udp_node')

    rate = rospy.Rate(10)  # 10Hz 发布频率
    while not rospy.is_shutdown():
        # 构建消息
        ground_msg = 1_GroundObject()
        ground_msg.UTC_time = rospy.Time.now().to_sec() * 1000  # 毫秒
        ground_msg.VehicleNumber = 5  # 示例车辆数量
        
        vehicle_obj = VEHICLE_OBJ_COOP()
        vehicle_obj.class = 1  # 车辆
        vehicle_obj.ismove = 1  # 移动状态
        vehicle_obj.vehicleclass = 0  # HM 类别
        vehicle_obj.lon = 120.123456  # 示例经度
        vehicle_obj.lat = 30.123456   # 示例纬度
        
        # 添加到数组中
        ground_msg.VehicleObjectCOOP.append(vehicle_obj)

        # 发布消息
        pub.publish(ground_msg)
        rate.sleep()

if __name__ == '__main__':
    try:
        algorithm_publish()
    except rospy.ROSInterruptException:
        pass
    finally:
        udp_sock.close()

运行：
rosrun your_package algorithm_and_udp_node.py