文章目录
前言
环境:
1、ubuntu20.0.4
2、ros
3、vscode
一、工作空间与功能包的创建
1、工作空间的创建
- alt+n新建一个终端用于创建工作空间;
- 代码:
mkdir -p ~/catkin_ws/src#创建文件夹
cd ~/catkin_ws/src#进入目录
catkin_init_workspace#初始化,使其成为ROS的工作空间
- 回到上一级目录编译工作空间:
cd ..
catkin_make
- 错误:
- 分析:
在ubuntu系统中,存在两个python;python2.7和python3.8;又装了一个conda后,出现了第三个版本的python3.9,所以需要改为指定采用下面的命令。
catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3
- 工作空间编译成功:
- 此时文件目录发生变化:
- 输入code打开进行编程:
- 设置环境变量:
source devel/setup.bash
- 检测环境变量:
echo $ROS_PACKAGE_PATH
2、功能包的创建
进入src目录下键入下面命令创建功能包
catkin_create_pkg learning_communication std_msgs rospy roscpp
#格式分别是catkin_create_pkg+功能包名+定义的标准的数据结构+提供的编程接口
- 查看功能包文件夹:
- 编译功能包:
- 回到上一级目录编译功能包:
cd ~/catkin_ws
catkin_make
- 编译成功:
二、话题编程
1.创建发布者
1、初始化ROS节点
2、向ROS Master注册节点信息,包括发布的话题名和话题中的消息类型
3、按照一定频率循环发布消息
- 新建talker.cpp文件:
- 代码:
#include<sstream>
#include"ros/ros.h"
#include"std_msgs/String.h"
int main(int argc,char **argv)
{
setlocale(LC_CTYPE, "zh_CN.utf8");
//ROS节点初始化
ros::init(argc,argv,"talker");
//创建节点句柄
ros::NodeHandle n;
//创建一个Publisher,发布名为chatter的topic,消息类型为std_msgs::String
ros::Publisher chatter_pub=n.advertise<std_msgs::String>("chatter",1000);
//设置循环的频率
ros::Rate loop_rate(10);
int count=0;
while(ros::ok())
{
//初始化std_msgs::String类型的消息
std_msgs::String msg;
std::stringstream ss;
ss<<"你好:混子王江江!"<<count;
msg.data=ss.str();
//发布消息
ROS_INFO("%s",msg.data.c_str());
chatter_pub.publish(msg);
//循环等待回调函数
ros::spinOnce();
//接受循环频率延时
loop_rate.sleep();
++count;
}
return 0;
}
2.创建订阅者
1、初始化ROS节点
2、订阅需要的话题
3、循环等待话题消息,接受到消息后进行回调函数回调函数中完成消息处理
- 新建listener.cpp文件:
- 代码:
#include"ros/ros.h"
#include"std_msgs/String.h"
//接收到订阅的消息,会进入消息的回调函数
void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
//将接收到的消息打印处理
ROS_INFO("I heard:{%s}",msg->data.c_str());
}
int main(int argc,char **argv)
{
setlocale(LC_CTYPE, "zh_CN.utf8");
//初始化ROS节点
ros::init(argc,argv,"listener");
//创建节点句柄
ros::NodeHandle n;
//创建一个Subscriber,订阅名为chatter的topic,注册回调函数chatterCallback
ros::Subscriber sub=n.subscribe("chatter",1000,chatterCallback);
//循环等待回调函数
ros::spin();
return 0;
}
3、修改CMakeLists.txt文件内容
- 在下面位置输入下面的内容:
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${
catkin_LIBRARIES})
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${
catkin_LIBRARIES})
- 键入catkin_make编译:
编译成功!
4、测试
- 打开三个终端测试:
roscore
rosrun learning_communication talker
rosrun learning_communication listener
测试成功!
三、服务编程
1、定义服务请求与应答的方式
- List item
- 创建srv目录及AddTwoInts.srv文件:
- AddTwoInts.srv文件内容:
int64 a
int64 b
---
int64 sum
- 在package.xml中添加功能包依赖:
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>
- 修改CMakeLists.txt文件内容:
message_generation
CATKIN DEPENDS roscpp rospy std msgs message runtime
add_service_files(
FILES AddTowInts.srv
# Service1.srv
# Service2.srv
)
2、创建服务端
1、初始化ROS节点
2、创建Serve实例
3、循环等待服务请求,进入回调函数
4、在回调函数中完成服务功能的处理,并反馈应答数据
- server.cpp文件:
#include<ros/ros.h>
#include"learning_communication/AddTwoInts.h"
//service回调函数,输入参数req,输出参数res
bool add(learning_communication::AddTwoInts::Request &req,learning_communication::AddTwoInts::Response &res)
{
//将输入的参数中的请求数据相加,结果放到应答变量中
res.sum=req.a+req.b;
ROS_INFO("request: x=%1d,y=%1d",(long int)req.a,(long int)req.b);
ROS_INFO("sending back response:[%1d]",(long int)res.sum);
return true;
}
int main(int argc,char **argv)
{
//ROS节点初始化
ros::init(argc,argv,"add_two_ints_server");
//创建节点句柄
ros::NodeHandle n;
//创建一个名为add_two_ints的server,注册回调函数add()
ros::ServiceServer service=n.advertiseService("add_two_ints",add);
//循环等待回调函数
ROS_INFO("Ready to add two ints.");
ros::spin();
return 0;
}
3、创建客户端
1、初始化ROS节点
2、创建一个Client实例
3、发布服务请求数据
4、等待Serve处理之后的应答结果
- client.cpp文件:
#include<cstdlib>
#include<ros/ros.h>
#include"learning_communication/AddTwoInts.h"
int main(int argc,char **argv)
{
//ROS节点初始化
ros::init(argc,argv,"add_two_ints_client");
//从终端命令行获取两个加数
if(argc!=3)
{
ROS_INFO("usage:add_two_ints_client X Y");
return 1;
}
//创建节点句柄
ros::NodeHandle n;
//创建一个client,请求add_two_ints_service
//service消息类型是learning_communication::AddTwoInts
ros::ServiceClient client=n.serviceClient<learning_communication::AddTwoInts>("add_two_ints");
//创建learning_communication::AddTwoInts类型的service消息
learning_communication::AddTwoInts srv;
srv.request.a=atoll(argv[1]);
srv.request.b=atoll(argv[2]);
//发布service请求,等待加法运算的应答请求
if(client.call(srv))
{
ROS_INFO("sum: %1d",(long int)srv.response.sum);
}
else
{
ROS_INFO("Failed to call service add_two_ints");
return 1;
}
return 0;
}
- 设置CMakeLists.txt文件:
- 代码:
add_executable(server src/server.cpp)
target_link_libraries(server ${
catkin_LIBRARIES})
add_dependencies(server ${
PROJECT_NAME}_gencpp)
add_executable(client src/client.cpp)
target_link_libraries(client ${
catkin_LIBRARIES})
add_dependencies(client ${
PROJECT_NAME}_gencpp)
- 编译通过:
4、测试
- 开三个终端进行测试:
roscore
rosrun learning_communication server
rosrun learning_communication client 整数1 整数2
- 效果:
四、动作编程
- 任务:
客户端发送一个运动坐标,模拟机器人运动到目标位置的过程。包括服务端和客户端的代码实现,要求带有实时位置反馈。
1、新建action文件夹和TurtleMove.action文件
- 代码:
# Define the goal
float64 turtle_target_x # Specify Turtle's target position
float64 turtle_target_y
float64 turtle_target_theta
---
# Define the result
float64 turtle_final_x
float64 turtle_final_y
float64 turtle_final_theta
---
# Define a feedback message
float64 present_turtle_x
float64 present_turtle_y
float64 present_turtle_theta
2、 新建turtleMove.cpp服务文件:
- 代码:
/*
此程序通过通过动作编程实现由client发布一个目标位置
然后控制Turtle运动到目标位置的过程
*/
#include <ros/ros.h>
#include <actionlib/server/simple_action_server.h>
#include "learning_communication/TurtleMoveAction.h"
#include <turtlesim/Pose.h>
#include <turtlesim/Spawn.h>
#include <geometry_msgs/Twist.h>
typedef actionlib::SimpleActionServer<learning_communication::TurtleMoveAction> Server;
struct Myturtle
{
float x;
float y;
float theta;
}turtle_original_pose,turtle_target_pose;
ros::Publisher turtle_vel;
void posecallback(const turtlesim::PoseConstPtr& msg)
{
ROS_INFO("Turtle1_position:(%f,%f,%f)",msg->x,msg->y,msg->theta);
turtle_original_pose.x=msg->x;
turtle_original_pose.y=msg->y;
turtle_original_pose.theta=msg->theta;
}
// 收到action的goal后调用该回调函数
void execute(const learning_communication::TurtleMoveGoalConstPtr& goal, Server* as)
{
learning_communication::TurtleMoveFeedback feedback;
ROS_INFO("TurtleMove is working.");
turtle_target_pose.x=goal->turtle_target_x;
turtle_target_pose.y=goal->turtle_target_y;
turtle_target_pose.theta=goal->turtle_target_theta;
geometry_msgs::Twist vel_msgs;
float break_flag;
while(1)
{
ros::Rate r(10);
vel_msgs.angular.z = 4.0 * (atan2(turtle_target_pose.y-turtle_original_pose.y,
turtle_target_pose.x-turtle_original_pose.x)-turtle_original_pose.theta);
vel_msgs.linear.x = 0.5 * sqrt(pow(turtle_target_pose.x-turtle_original_pose.x, 2) +
pow(turtle_target_pose.y-turtle_original_pose.y, 2));
break_flag=sqrt(pow(turtle_target_pose.x-turtle_original_pose.x, 2) +
pow(turtle_target_pose.y-turtle_original_pose.y, 2));
turtle_vel.publish(vel_msgs);
feedback.present_turtle_x=turtle_original_pose.x;
feedback.present_turtle_y=turtle_original_pose.y;
feedback.present_turtle_theta=turtle_original_pose.theta;
as->publishFeedback(feedback);
ROS_INFO("break_flag=%f",break_flag);
if(break_flag<0.1) break;
r.sleep();
}
// 当action完成后,向客户端返回结果
ROS_INFO("TurtleMove is finished.");
as->setSucceeded();
}
int main(int argc, char** argv)
{
ros::init(argc, argv, "TurtleMove");
ros::NodeHandle n,turtle_node;
ros::Subscriber sub = turtle_node.subscribe("turtle1/pose",10,&posecallback); //订阅小乌龟的位置信息
turtle_vel = turtle_node.advertise<geometry_msgs::Twist>("turtle1/cmd_vel",10);//发布控制小乌龟运动的速度
// 定义一个服务器
Server server(n, "TurtleMove", boost::bind(&execute, _1, &server), false);
// 服务器开始运行
server.start();
ROS_INFO("server has started.");
ros::spin();
return 0;
}
3、新建turtleMoveClient.cpp文件,用于发布位置:
- 代码:
#include <actionlib/client/simple_action_client.h>
#include "learning_communication/TurtleMoveAction.h"
#include <turtlesim/Pose.h>
#include <turtlesim/Spawn.h>
#include <geometry_msgs/Twist.h>
typedef actionlib::SimpleActionClient<learning_communication::TurtleMoveAction> Client;
struct Myturtle
{
float x;
float y;
float theta;
}turtle_present_pose;
// 当action完成后会调用该回调函数一次
void doneCb(const actionlib::SimpleClientGoalState& state,
const learning_communication::TurtleMoveResultConstPtr& result)
{
ROS_INFO("Yay! The TurtleMove is finished!");
ros::shutdown();
}
// 当action激活后会调用该回调函数一次
void activeCb()
{
ROS_INFO("Goal just went active");
}
// 收到feedback后调用该回调函数
void feedbackCb(const learning_communication::TurtleMoveFeedbackConstPtr& feedback)
{
ROS_INFO(" present_pose : %f %f %f", feedback->present_turtle_x,
feedback->present_turtle_y,feedback->present_turtle_theta);
}
int main(int argc, char** argv)
{
ros::init(argc, argv, "TurtleMove_client");
// 定义一个客户端
Client client("TurtleMove", true);
// 等待服务器端
ROS_INFO("Waiting for action server to start.");
client.waitForServer();
ROS_INFO("Action server started, sending goal.");
// 创建一个action的goal
learning_communication::TurtleMoveGoal goal;
goal.turtle_target_x = 1;
goal.turtle_target_y = 1;
goal.turtle_target_theta = 0;
// 发送action的goal给服务器端,并且设置回调函数
client.sendGoal(goal, &doneCb, &activeCb, &feedbackCb);
ros::spin();
return 0;
}
4、修改CMakeList.txt文件
find_package(catkin REQUIRED COMPONENTS
roscpp
rospy
std_msgs
message_generation
actionlib_msgs
actionlib
)
add_action_files(
FILES TurtleMove.action
)
generate_messages(
DEPENDENCIES
std_msgs
actionlib_msgs
)
add_executable(turtleMoveClient src/turtleMoveClient.cpp)
target_link_libraries(turtleMoveClient ${
catkin_LIBRARIES})
add_dependencies(turtleMoveClient ${
PROJECT_NAME}_gencpp)
add_executable(turtleMove src/turtleMove.cpp)
target_link_libraries(turtleMove ${
catkin_LIBRARIES})
add_dependencies(turtleMove ${
PROJECT_NAME}_gencpp)
- 修改package.xml文件:
<build_depend>message_generation</build_depend>
<build_depend>actionlib</build_depend>
<build_depend>actionlib_msgs</build_depend>
<exec_depend>message_runtime</exec_depend>
<exec_depend>actionlib</exec_depend>
<exec_depend>actionlib_msgs</exec_depend>
- 编译成功:
5、测试
依次打开四个终端运行:
roscore
rosrun turtlesim turtlesim_node
rosrun learning_communication turtleMove
rosrun learning_communication turtleMoveClient
五、总结
这里学习了三种通信方式,话题、服务、动作等三种方式,我觉得难度在一级级的增加。通过这次作业,对三种通信方式的具体实现步骤有了更加清晰的了解,尤其对Cmaketext的文件的理解更深入。不足的是这次的分布式通信没有完成,总是出现各种各样的问题、ping不通或者是控制不了,云服务和其他电脑都试过了都不行,等下次看能不能实现在发表博客。