ROS1学习第二弹
本文纯属记录学习过程,所学教程来自B站古月居ROS入门21讲
ROS1学习第一弹
二、关于代码
1.必有内容:
// ROS节点初始化ros::init(argc, argv, "parameter_config");// 创建节点句柄ros::NodeHandle node;
- 文件结构:/catkin_ws/src 中
src
├── CMakeLists.txt -> /opt/ros/noetic/share/catkin/cmake/toplevel.cmake
├── learning_parameter
│ ├── CMakeLists.txt
│ ├── include
│ │ └── learning_parameter
│ ├── package.xml
│ └── src
│ └── parameter_config.cpp
├── learning_service
│ ├── CMakeLists.txt
│ ├── include
│ │ └── learning_service
│ ├── package.xml
│ ├── src
│ │ ├── person_client.cpp
│ │ ├── person_server.cpp
│ │ ├── turtle_command_server.cpp
│ │ └── turtle_spawn.cpp
│ └── srv
│ └── Person.srv
└── learning_topic
├── CMakeLists.txt
├── include
│ └── learning_topic
├── msg
│ └── Person.msg
├── package.xml
└── src
├── person_publisher.cpp
├── person_subscriber.cpp
├── pose_subscriber.cpp
└── velocity_publisher.cpp
其中比如 └── learning_topic就是一个功能包,靠catkin_create_pkg生成,语法是catkin_create_pkg my_cpp_pkg roscpp std_msgs
3.Topic :Publisher 与 Subscriber
在功能包下面建立msg文件夹,里面.msg文件定义消息类型,整个包编译一边就能在/devel/include/下面看见具体实现定义消息类型的文件
publisher:
#include<ros/ros.h>
#include"learning_topic/Person.h"int main(int argc,char **argv)
{ros::init(argc, argv, "person_publisher");ros::NodeHandle n;// 创建Publisher对象(话题名、队列长度)ros::Publisher person_info_pub=n.advertise<learning_topic::Person>("/person_info",10);// 设置循环频率ros::Rate loop_rate(1);int count=0;while(ros::ok()){learning_topic::Person person_msg; // 创建消息对象person_msg.name="Tom";person_msg.age=18;person_msg.sex=learning_topic::Person::male;person_info_pub.publish(person_msg); // 发布消息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(); // 控制循环频率}return 0;
}
subscriber:
#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;// learning_topic::Person是自定义的消息类型// person_info_sub是订阅者对象// "/person_info"是话题名称 与publisher发布的名称一致// 10是队列长度,表示订阅者的消息队列长度// 当消息队列满时,旧消息会被丢弃// personInfoCallback是回调函数,当有新消息到来时会调用此函数处理消息// 该函数的参数是一个指向ConstPtr的指针,ConstPtr是指向常量的智能指针// 这样可以避免复制消息,提高效率// 订阅者会在后台自动处理消息队列// 当有新消息到来时,回调函数会被调用// 回调函数可以访问消息内容,并进行相应的处理ros::Subscriber person_info_sub=n.subscribe("/person_info",10,personInfoCallback);//ros::spin();return 0;
}
4.Service:Client 与 Server
在功能包下面建立srv文件夹,里面.srv文件定义消息类型,整个包编译一边就能在/devel/include/下面看见具体实现定义消息类型的文件
client:
#include<ros/ros.h>
#include<learning_service/Person.h>int main(int argc,char ** argv)
{ros::init(argc,argv,"person_client");ros::NodeHandle node;// 等待服务可用(类似中断)ros::service::waitForService("/show_person");// 创建服务客户端ros::ServiceClient person_client=node.serviceClient<learning_service::Person>("/show_person");learning_service::Person srv;srv.request.name="Tom";srv.request.age=20;srv.request.sex=learning_service::Person::Request::male;ROS_INFO("Call service to show person[name:%s, age:%d, sex:%d]",srv.request.name.c_str(), srv.request.age,srv.request.sex);person_client.call(srv); // 调用服务ROS_INFO("Showperson result: %s", srv.response.result.c_str());return 0;
}
server:
#include<ros/ros.h>
#include"learning_service/Person.h"bool personCallback(learning_service::Person::Request &req, // 引用传递,接绑定到客户端发送的请求对象learning_service::Person::Response &res) {ROS_INFO("Person: Name: %s, Age: %d, sex:%d", req.name.c_str(), req.age,req.sex);res.result="OK";return true;
}int main(int argc,char **argv)
{ros::init(argc,argv,"person_server");ros::NodeHandle n;// 创建服务ros::ServiceServer person_service=n.advertiseService("/show_person",personCallback); ROS_INFO("Person service is ready.");ros::spin();return 0;
}
5.rosparam的使用:
rosparam is a command-line tool for getting, setting, and deleting parameters from the ROS Parameter Server.
Commands:
rosparam set set parameter
rosparam get get parameter
rosparam load load parameters from file
rosparam dump dump parameters to file
rosparam delete delete parameter
rosparam list list parameter names