ros中自定义数据类型传送msg，并且发布和订阅该消息（python代码）

msg

1 .定义
2.订阅自定义信息的代码
3.订阅自定义信息的代码
4.文件夹结构
5.文件夹创建，编译和运行的步骤
- 5.1 创建ROS工作空间
- 5.2 编译
- 5.3 CMakeLists.txt文件修改
- 5.4 package.xml修改
- 5.5 修改后再次编译
6.运行发布者和订阅者
- 6.1 启动核心
- 6.2 一个终端运行发布者节点
- 6.3 一个终端运行订阅者节点

1 .定义

假设我在无人车，无人机，地面基站之间要传送一系列目标的信息，现在要自定义传输的目标的ros格式，就需要msg文件。

GroundObject.msg文件内容为：

float64 UTC_time		# in msint32 VehicleNumber                    
VEHICLE_OBJ_COOP[] VehicleObjectCOOP

VEHICLE_OBJ_COOP.msg文件内容是：

int32 class      # 0:unknow 1:car 2:ped
int32 ismove
int32 vehicleclass  # 0:HM 1:LM 3:objects
float64 lon    	
float64 lat

VEHICLE_OBJ_COOP[] 表示一个包含车辆信息的数组，其中每个元素使用的是另一个自定义消息类型VehicleObjectCOOP，在VEHICLE_OBJ_COOP.msg文件中定义。

2.订阅自定义信息的代码

#!/usr/bin/env pythonimport rospy
from your_package.msg import GroundObject, VEHICLE_OBJ_COOP  # Import the custom messagesdef publisher():# 初始化发布节点rospy.init_node('ground_station_publisher', anonymous=True)# 创建发布者，发布到 'ground_object_topic' 话题，消息类型为 GroundObjectpub = rospy.Publisher('ground_object_topic', GroundObject, queue_size=10)rate = rospy.Rate(1)  # 设置发布频率为 1Hzwhile not rospy.is_shutdown():# 创建 GroundObject 消息ground_msg = GroundObject()ground_msg.UTC_time = rospy.get_time()  # 使用 ROS 时间作为 UTC 时间ground_msg.VehicleNumber = 2  # 假设有两辆车# 创建第一个 VEHICLE_OBJ_COOP 对象vehicle1 = VEHICLE_OBJ_COOP()vehicle1.class = 1  # 车辆vehicle1.ismove = 1  # 正在移动vehicle1.vehicleclass = 0  # 类别为 HMvehicle1.lon = 120.1vehicle1.lat = 30.1# 创建第二个 VEHICLE_OBJ_COOP 对象vehicle2 = VEHICLE_OBJ_COOP()vehicle2.class = 2  # 行人vehicle2.ismove = 0  # 不移动vehicle2.vehicleclass = 3  # 类别为 objectsvehicle2.lon = 121.2vehicle2.lat = 31.2# 将车辆对象放入 GroundObject 消息中的数组ground_msg.VehicleObjectCOOP = [vehicle1, vehicle2]# 发布消息pub.publish(ground_msg)rospy.loginfo("Published GroundObject message: %s", ground_msg)rate.sleep()if __name__ == '__main__':try:publisher()except rospy.ROSInterruptException:pass

3.订阅自定义信息的代码

#!/usr/bin/env pythonimport rospy
from your_package.msg import GroundObject, VEHICLE_OBJ_COOP  # Import the custom messagesdef callback(data):rospy.loginfo("Received GroundObject message at UTC_time: %f", data.UTC_time)rospy.loginfo("Vehicle count: %d", data.VehicleNumber)for idx, vehicle in enumerate(data.VehicleObjectCOOP):rospy.loginfo("Vehicle %d -> Class: %d, IsMoving: %d, VehicleClass: %d, Lon: %f, Lat: %f",idx, vehicle.class, vehicle.ismove, vehicle.vehicleclass, vehicle.lon, vehicle.lat)def listener():# 初始化订阅节点rospy.init_node('ground_station_subscriber', anonymous=True)# 创建订阅者，订阅 'ground_object_topic' 话题，消息类型为 GroundObjectrospy.Subscriber('ground_object_topic', GroundObject, callback)rospy.spin()  # 保持节点持续运行if __name__ == '__main__':listener()

4.文件夹结构

your_catkin_ws/                 # ROS工作空间
├── src/
│   ├── your_package/           # 你的ROS包
│   │   ├── CMakeLists.txt      # ROS包的CMake配置文件
│   │   ├── package.xml         # ROS包的XML配置文件
│   │   ├── msg/                # 消息定义文件夹
│   │   │   ├── GroundObject.msg
│   │   │   ├── VEHICLE_OBJ_COOP.msg
│   │   ├── src/            # Python脚本存放目录
│   │   │   ├── publisher_node.py  # 发布者节点脚本
│   │   │   ├── subscriber_node.py  # 订阅者节点脚本

from your_package.msg import GroundObject, VEHICLE_OBJ_COOP
所以从your_package的msg文件夹里，引用GroundObject, VEHICLE_OBJ_COOP两个msg文件

5.文件夹创建，编译和运行的步骤

5.1 创建ROS工作空间

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/src
catkin_create_pkg your_package std_msgs rospy roscpp #创建了一个包

#这一步后会在your_package中生成下面几个文件

~/catkin_ws/
├── src/
│   ├── your_package/
│   │   ├── CMakeLists.txt
│   │   ├── package.xml
│   │   ├── src

5.2 编译

cd ~/catkin_ws
catkin_make

这一步以后文件架构变为如下：也就是多了build和devel

~/catkin_ws/
├── src/
│   ├── your_package/
│   │   ├── CMakeLists.txt
│   │   ├── package.xml
│   │   ├── launch 
│   │   ├── src/
│   │   │   └──  publisher_node.py
│   │   │   └──  subscriber_node.py
└── build
└── devel

5.3 CMakeLists.txt文件修改

cmake_minimum_required(VERSION 3.0.2)
project(your_package)## 找到catkin依赖
find_package(catkin REQUIRED COMPONENTSrospystd_msgsmessage_generation  # 添加这一行用于生成消息
)## 添加消息文件
add_message_files(FILESGroundObject.msg     # 添加你的消息文件VEHICLE_OBJ_COOP.msg
)## 生成消息
generate_messages(DEPENDENCIESstd_msgs  # 如果你的消息依赖于标准消息类型
)## 声明catkin包
catkin_package(CATKIN_DEPENDS message_runtime std_msgs
)include_directories(${catkin_INCLUDE_DIRS}
)

5.4 package.xml修改

package.xml 也需要包括生成自定义消息的配置。确保文件中包含了 message_generation 和 message_runtime 依赖：

<package format="2"><name>your_package</name><version>0.0.0</version><description>The your_package package</description><maintainer email="user@domain.com">Your Name</maintainer><license>BSD</license><buildtool_depend>catkin</buildtool_depend><build_depend>message_generation</build_depend><exec_depend>message_runtime</exec_depend><build_depend>rospy</build_depend><exec_depend>rospy</exec_depend><build_depend>std_msgs</build_depend><exec_depend>std_msgs</exec_depend></package>