ROS话题的定义和使用
自定义话题消息
自定义话题消息主要包括以下步骤:
- 定义msg文件
- 在package.xml中添加功能中依赖
- 在CMakeList.txt中添加编译规则
- 编译生成语言相关文件
- 编写.msg文件
进入要定义.msg文件的功能包文件夹,创建新的文件夹名为msg
$ cd ~/catkin_ws/src/learning_topic
$ mkdir msg
$ cd msg
$ touch Person.msg
打开msg文件编辑
string name
uint8 age
uint8 sex
uint8 unknown = 0 //宏定义
uint8 male = 1 //宏定义
uint8 female = 2 //宏定义
- 添加依赖
打开功能包文件夹内的package.xml文件,添加如下语句
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>
- 首先在find_package中添加 message_generation
2. 编译目标
首先在CMakeList.txt 锁定到以下位置
## Generate added messages and services with any dependencies listed here
# generate_messages(
# DEPENDENCIES
# geometry_msgs# std_msgs
# )
<-------就是这儿!!!!!
################################################
## Declare ROS dynamic reconfigure parameters ##
################################################
添加
add_message_files(FILES Person.msg)
generate_message(DEPENDENCIES std_msgs)
add_message_files(FILES Person.msg) 是用来把Person.msg 作为定义的接口针对它进行编译
generate_message(DEPENDENCIES std_msgs) 编译上面的.msg文件的时候要依赖哪些ros已有的库和包,像上面的string和uint8 都是在std_msgs中定义的。
- 运行依赖
首先在CMakeList.txt 锁定到以下位置
###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
# INCLUDE_DIRS include
# LIBRARIES learning_topic
# CATKIN_DEPENDS geometry_msgs roscpp rospy std_msgs turtlesim <--就是这儿!!!!!
# DEPENDS system_lib
)
删去当前行的#号,然后添加msg的运行依赖库message_runtime
###################################
## catkin specific configuration ##
###################################
## The catkin_package macro generates cmake config files for your package
## Declare things to be passed to dependent projects
## INCLUDE_DIRS: uncomment this if your package contains header files
## LIBRARIES: libraries you create in this project that dependent projects also need
## CATKIN_DEPENDS: catkin_packages dependent projects also need
## DEPENDS: system dependencies of this project that dependent projects also need
catkin_package(
# INCLUDE_DIRS include
# LIBRARIES learning_topic
CATKIN_DEPENDS geometry_msgs roscpp rospy std_msgs turtlesim message_runtime
# DEPENDS system_lib
)
到目前为止,已经完成了msg定义的准备工作,接下来就是编译
$ catkin_make
成功后的指令反馈为
编译成功之后生成的代码文件如下
workspace_name/devel/include/package_name/???.h
???.h 文件就是???.msg编译得到的cpp头文件。
调用自定义的话题消息
接下来定义两个文件,分别注册两个节点,由第二个节点订阅第一个节点的话题消息
- 注册发布者节点
程序来自古月居ROS21讲
#include <ros/ros.h>
#include "learning_topic/Person.h"
int main(int argc, char **argv)
{
ros::init(argc, argv, "person_publisher");
ros::NodeHandle n;
ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);
ros::Rate loop_rate(1);
int count = 0;
while (ros::ok())
{
learning_topic::Person person_msg;
person_msg.name = "Tom";
person_msg.age = 18;
person_msg.sex = learning_topic::Person::male;
person_info_pub.publish(person_msg);
ROS_INFO("Publish Person Info: name:%s age:%d sex:%d",
person_msg.name.c_str(), person_msg.age, person_msg.sex);
loop_rate.sleep();
}
return 0;
}
- 注册订阅者节点
程序来自古月居ROS21讲
#include <ros/ros.h>
#include "learning_topic/Person.h"
void personInfoCallback(const learning_topic::Person::ConstPtr& msg)
{
ROS_INFO("Subcribe Person Info: name:%s age:%d sex:%d",
msg->name.c_str(), msg->age, msg->sex);
}
int main(int argc, char **argv)
{
ros::init(argc, argv, "person_subscriber");
ros::NodeHandle n;
ros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);
ros::spin();
return 0;
}
- 修改CMakeList.txt编译规则
add_executable(person_publisher src/person_publisher.cpp)
target_link_libraries(person_publisher ${catkin_LIBRARIES})
add_dependencies(person_publisher ${PROJECT_NAME}_generate_messages_cpp)
add_executable(person_subscriber src/person_subscriber.cpp)
target_link_libraries(person_subscriber ${catkin_LIBRARIES})
add_dependencies(person_subscriber ${PROJECT_NAME}_generate_messages_cpp)
这里增加了一行add_dependencies,这是因为有些代码是动态生成的,所以需要我们的可执行文件和动态生成的一些程序建立依赖关系
-
编译
回到工作空间根目录执行编译指令
-
设置环境变量
-
检查环境变量
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