ROS入门21讲笔记——古月居

一时失言乱红尘 2023-06-27 03:42 4阅读 0赞

**提示：**  
1、 在 **catkin\_ws** 文件下运行`catkin_make`  
2、 在 **catkin\_ws** 文件下运行`source devel/setup.bash`  
3、 在 **catkin\_ws** 文件下运行`rosrun learning_topic pose_subscriber`  
4、 基本上所有操作都是在自己创建的话题文件夹下进行操作  
5、 海归仿真器启动可以在任意文件夹下启动  
**启动流程：**  
1、 `roscore`  
2、 `rosrun turtlesim turtlesim_node` \#打开海归仿真器  
3、 `rosrun turtlesim turtlesim_teleop_key` \#启动键盘控制海归

**CMakeLists.txt文件一般添加**

add_executable(pose_subscriber src/pose_subscriber.cpp)
    target_link_libraries(pose_subscriber ${catkin_LIBRARIES})

## ROS入门21讲笔记——古月居 ##

*  1 C++&Python极简基础
 *   *  1.1 安装编译/解析器
     *  1.2 for循环
     *  1.3 while循环
     *  1.4 面向对象
 *  2. ROS基础
 *   *  2.1 ROS概念
     *  2.2 创建工作空间与功能包
     *  2.3 发布者Publisher的编程实现
     *  2.4 订阅者Subscriber的编程实现
     *  2.5 话题消息的定义与使用
     *  2.6 客户端Client的编程实现
     *  2.7 服务端Server的编程实现
     *  2.8 服务数据的定义与使用
     *  2.9 参数的使用与编程方法
     *  2.10 tf坐标系广播与监听的编程实现
     *  2.11 launch启动文件的使用方法
     *  2.12 常用可视化工具的使用
     *   *  2.12.1 rqt
         *  2.12.2 Rviz
         *  2.12.3 Gazebo

--------------------

番外篇：

*  101、ROS打开bag文件
 *  102、ROS打开pcap文件

# 1 C++&Python极简基础 #

## 1.1 安装编译/解析器 ##

sudo apt-get install g++
    sudo apt-get install python

## 1.2 for循环 ##

*  Python

for a in range(5,10):
    	if a< 10:
    		print 'a = ',a
    		a+=1
    	else:
    		break

--------------------

使用Python解析器运行py程序

python fileName.py

--------------------

*  C++  
    略

--------------------

使用g++编译\*.cpp文件

g++  fileName.cpp  -o  exeFileName

运行编译后的二进制文件

./exeFileName

--------------------

## 1.3 while循环 ##

*  C++  
    略
 *  Python

a = 5
    while a < 10:
    	print 'a = ' , a
    	a += 1

## 1.4 面向对象 ##

*  C++

#include <iostream>
    class A
    {
    	public:
    		int i;
    		void test()
    		{
    			std::cout << i <<std::endl;
    		}
    };
    int main()
    {
    	A a;
    	a.i = 10;
    	a.test();
    	return 0;
    }

*  Python

class A:
    	i = 10
    	def test(self)
    		print self.i
    a = A()
    a.test()

--------------------

> 配置ROS软件源时,更新软件包容易出现下载失败的情况,跟使用的网络有关.  
> 古月大神总结:使用手机热点可以更新成功.

--------------------

# 2. ROS基础 #

## 2.1 ROS概念 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 1]  
查看节点列表:rosnode list  
发布话题消息:rostopic pub -r 10 /话题名  
发布服务请求:rosservice call /服务文件 “变量:val”  
话题记录: rosbag record -a -O fileName  
话题复现: rosbag play fileName

## 2.2 创建工作空间与功能包 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 2]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 3]  
建立install空间:catkin\_make install 输入catkin\_make 出现make -j4 -l4 没有问题

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 4]

## 2.3 发布者Publisher的编程实现 ##

![在这里插入图片描述][20190717161618969.png]

--------------------

*  C++

/**
     * 该例程将发布turtle1/cmd_vel话题，消息类型geometry_msgs::Twist
     */
    #include <ros/ros.h>
    #include <geometry_msgs/Twist.h>
    int main(int argc, char **argv)
    {
    	// ROS节点初始化
    	ros::init(argc, argv, "velocity_publisher");
    	// 创建节点句柄
    	ros::NodeHandle n;
    	// 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10
    	ros::Publisher turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10);
    	// 设置循环的频率
    	ros::Rate loop_rate(10);
    	int count = 0;
    	while (ros::ok())
    	{
    	    // 初始化geometry_msgs::Twist类型的消息
    		geometry_msgs::Twist vel_msg;
    		vel_msg.linear.x = 0.5;
    		vel_msg.angular.z = 0.2;
    	    // 发布消息
    		turtle_vel_pub.publish(vel_msg);
    		ROS_INFO("Publsh turtle velocity command[%0.2f m/s, %0.2f rad/s]", 
    				vel_msg.linear.x, vel_msg.angular.z);
    	    // 按照循环频率延时
    	    loop_rate.sleep();
    	}
    	return 0;
    }

![在这里插入图片描述][20190717162023634.png]  
![在这里插入图片描述][20190717162037884.png]

*  Python

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将发布turtle1/cmd_vel话题，消息类型geometry_msgs::Twist
    import rospy
    from geometry_msgs.msg import Twist
    def velocity_publisher():
    	# ROS节点初始化
        rospy.init_node('velocity_publisher', anonymous=True)
    	# 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10
        turtle_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
    	#设置循环的频率
        rate = rospy.Rate(10) 
        while not rospy.is_shutdown():
    		# 初始化geometry_msgs::Twist类型的消息
            vel_msg = Twist()
            vel_msg.linear.x = 0.5
            vel_msg.angular.z = 0.2
    		# 发布消息
            turtle_vel_pub.publish(vel_msg)
        	rospy.loginfo("Publsh turtle velocity command[%0.2f m/s, %0.2f rad/s]", 
    				vel_msg.linear.x, vel_msg.angular.z)
    		# 按照循环频率延时
            rate.sleep()
    if __name__ == '__main__':
        try:
            velocity_publisher()
        except rospy.ROSInterruptException:
            pass

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 5]

## 2.4 订阅者Subscriber的编程实现 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 6]

--------------------

*  C++

/**
     * 该例程将订阅/turtle1/pose话题，消息类型turtlesim::Pose
     */
    #include <ros/ros.h>
    #include "turtlesim/Pose.h"
    // 接收到订阅的消息后，会进入消息回调函数
    void poseCallback(const turtlesim::Pose::ConstPtr& msg)
    {
        // 将接收到的消息打印出来
        ROS_INFO("Turtle pose: x:%0.6f, y:%0.6f", msg->x, msg->y);
    }
    int main(int argc, char **argv)
    {
        // 初始化ROS节点
        ros::init(argc, argv, "pose_subscriber");
        // 创建节点句柄
        ros::NodeHandle n;
        // 创建一个Subscriber，订阅名为/turtle1/pose的topic，注册回调函数poseCallback
        ros::Subscriber pose_sub = n.subscribe("/turtle1/pose", 10, poseCallback);
        // 循环等待回调函数
        ros::spin();
        return 0;
    }

![在这里插入图片描述][2019071716300154.png]  
![在这里插入图片描述][20190717163020198.png]

*  Python

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将订阅/turtle1/pose话题，消息类型turtlesim::Pose
    import rospy
    from turtlesim.msg import Pose
    def poseCallback(msg):
        rospy.loginfo("Turtle pose: x:%0.6f, y:%0.6f", msg.x, msg.y)
    def pose_subscriber():
    	# ROS节点初始化
        rospy.init_node('pose_subscriber', anonymous=True)
    	# 创建一个Subscriber，订阅名为/turtle1/pose的topic，注册回调函数poseCallback
        rospy.Subscriber("/turtle1/pose", Pose, poseCallback)
    	# 循环等待回调函数
        rospy.spin()
    if __name__ == '__main__':
        pose_subscriber()

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 7]

## 2.5 话题消息的定义与使用 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 8]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 9]

--------------------

*  C++

/**
     * 该例程将发布/person_info话题，自定义消息类型learning_topic::Person
     */
    #include <ros/ros.h>
    #include "learning_topic/Person.h"
    int main(int argc, char **argv)
    {
        // ROS节点初始化
        ros::init(argc, argv, "person_publisher");
        // 创建节点句柄
        ros::NodeHandle n;
        // 创建一个Publisher，发布名为/person_info的topic，消息类型为learning_topic::Person，队列长度10
        ros::Publisher person_info_pub = n.advertise<learning_topic::Person>("/person_info", 10);
        // 设置循环的频率
        ros::Rate loop_rate(1);
        int count = 0;
        while (ros::ok())
        {
            // 初始化learning_topic::Person类型的消息
        	learning_topic::Person person_msg;
    		person_msg.name = "Tom";
    		person_msg.age  = 18;
    		person_msg.sex  = learning_topic::Person::male;
            // 发布消息
    		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);
            // 按照循环频率延时
            loop_rate.sleep();
        }
        return 0;
    }

/**
     * 该例程将订阅/person_info话题，自定义消息类型learning_topic::Person
     */
    #include <ros/ros.h>
    #include "learning_topic/Person.h"
    // 接收到订阅的消息后，会进入消息回调函数
    void personInfoCallback(const learning_topic::Person::ConstPtr& msg)
    {
        // 将接收到的消息打印出来
        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)
    {
        // 初始化ROS节点
        ros::init(argc, argv, "person_subscriber");
        // 创建节点句柄
        ros::NodeHandle n;
        // 创建一个Subscriber，订阅名为/person_info的topic，注册回调函数personInfoCallback
        ros::Subscriber person_info_sub = n.subscribe("/person_info", 10, personInfoCallback);
        // 循环等待回调函数
        ros::spin();
        return 0;
    }

![在这里插入图片描述][20190717164232766.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 10]

*  Python

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将发布/person_info话题，自定义消息类型learning_topic::Person
    import rospy
    from learning_topic.msg import Person
    def velocity_publisher():
    	# ROS节点初始化
        rospy.init_node('person_publisher', anonymous=True)
    	# 创建一个Publisher，发布名为/person_info的topic，消息类型为learning_topic::Person，队列长度10
        person_info_pub = rospy.Publisher('/person_info', Person, queue_size=10)
    	#设置循环的频率
        rate = rospy.Rate(10) 
        while not rospy.is_shutdown():
    		# 初始化learning_topic::Person类型的消息
        	person_msg = Person()
        	person_msg.name = "Tom";
        	person_msg.age  = 18;
        	person_msg.sex  = Person.male;
    		# 发布消息
            person_info_pub.publish(person_msg)
        	rospy.loginfo("Publsh person message[%s, %d, %d]", 
    				person_msg.name, person_msg.age, person_msg.sex)
    		# 按照循环频率延时
            rate.sleep()
    if __name__ == '__main__':
        try:
            velocity_publisher()
        except rospy.ROSInterruptException:
            pass

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将订阅/person_info话题，自定义消息类型learning_topic::Person
    import rospy
    from learning_topic.msg import Person
    def personInfoCallback(msg):
        rospy.loginfo("Subcribe Person Info: name:%s  age:%d  sex:%d", 
    			 msg.name, msg.age, msg.sex)
    def person_subscriber():
    	# ROS节点初始化
        rospy.init_node('person_subscriber', anonymous=True)
    	# 创建一个Subscriber，订阅名为/person_info的topic，注册回调函数personInfoCallback
        rospy.Subscriber("/person_info", Person, personInfoCallback)
    	# 循环等待回调函数
        rospy.spin()
    if __name__ == '__main__':
        person_subscriber()

## 2.6 客户端Client的编程实现 ##

![在这里插入图片描述][20190717213836487.png]

*  C++

/**
     * 该例程将请求/spawn服务，服务数据类型turtlesim::Spawn
     */
    #include <ros/ros.h>
    #include <turtlesim/Spawn.h>
    int main(int argc, char** argv)
    {
        // 初始化ROS节点
    	ros::init(argc, argv, "turtle_spawn");
        // 创建节点句柄
    	ros::NodeHandle node;
        // 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
    	ros::service::waitForService("/spawn");//阻塞型函数
    	ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("/spawn");
        // 初始化turtlesim::Spawn的请求数据
    	turtlesim::Spawn srv;
    	srv.request.x = 2.0;
    	srv.request.y = 2.0;
    	srv.request.name = "turtle2";
        // 请求服务调用
    	ROS_INFO("Call service to spwan turtle[x:%0.6f, y:%0.6f, name:%s]", 
    			 srv.request.x, srv.request.y, srv.request.name.c_str());
    	add_turtle.call(srv); //阻塞型函数
    	// 显示服务调用结果
    	ROS_INFO("Spwan turtle successfully [name:%s]", srv.response.name.c_str());
    	return 0;
    };

![在这里插入图片描述][20190717214224409.png]  
![在这里插入图片描述][20190717214235913.png]

*  Python

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将请求/spawn服务，服务数据类型turtlesim::Spawn
    import sys
    import rospy
    from turtlesim.srv import Spawn
    def turtle_spawn():
    	# ROS节点初始化
        rospy.init_node('turtle_spawn')
    	# 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
        rospy.wait_for_service('/spawn')
        try:
            add_turtle = rospy.ServiceProxy('/spawn', Spawn)
    		# 请求服务调用，输入请求数据
            response = add_turtle(2.0, 2.0, 0.0, "turtle2")
            return response.name
        except rospy.ServiceException, e:
            print "Service call failed: %s"%e
    if __name__ == "__main__":
    	#服务调用并显示调用结果
        print "Spwan turtle successfully [name:%s]" %(turtle_spawn())

## 2.7 服务端Server的编程实现 ##

![在这里插入图片描述][2019071721491282.png]

*  C++

/**
     * 该例程将执行/turtle_command服务，服务数据类型std_srvs/Trigger
     */
    #include <ros/ros.h>
    #include <geometry_msgs/Twist.h>
    #include <std_srvs/Trigger.h>
    ros::Publisher turtle_vel_pub;
    bool pubCommand = false;
    // service回调函数，输入参数req，输出参数res
    bool commandCallback(std_srvs::Trigger::Request  &req,
             			std_srvs::Trigger::Response &res)
    {
    	pubCommand = !pubCommand;
        // 显示请求数据
        ROS_INFO("Publish turtle velocity command [%s]", pubCommand==true?"Yes":"No");
    	// 设置反馈数据
    	res.success = true;
    	res.message = "Change turtle command state!"
        return true;
    }
    int main(int argc, char **argv)
    {
        // ROS节点初始化
        ros::init(argc, argv, "turtle_command_server");
        // 创建节点句柄
        ros::NodeHandle n;
        // 创建一个名为/turtle_command的server，注册回调函数commandCallback
        ros::ServiceServer command_service = n.advertiseService("/turtle_command", commandCallback);
    	// 创建一个Publisher，发布名为/turtle1/cmd_vel的topic，消息类型为geometry_msgs::Twist，队列长度10
    	turtle_vel_pub = n.advertise<geometry_msgs::Twist>("/turtle1/cmd_vel", 10);
        // 循环等待回调函数
        ROS_INFO("Ready to receive turtle command.");
    	// 设置循环的频率
    	ros::Rate loop_rate(10);
    	while(ros::ok())
    	{
    		// 查看一次回调函数队列
        	ros::spinOnce();
    		// 如果标志为true，则发布速度指令
    		if(pubCommand)
    		{
    			geometry_msgs::Twist vel_msg;
    			vel_msg.linear.x = 0.5;
    			vel_msg.angular.z = 0.2;
    			turtle_vel_pub.publish(vel_msg);
    		}
    		//按照循环频率延时
    	    loop_rate.sleep();
    	}
        return 0;
    }

![在这里插入图片描述][20190717215318860.png]  
![在这里插入图片描述][20190717215332181.png]

*  Python

> 注意，ros在Python中没有spinonce方法，可通过多线程来实现

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将执行/turtle_command服务，服务数据类型std_srvs/Trigger
    import rospy
    import thread,time
    from geometry_msgs.msg import Twist
    from std_srvs.srv import Trigger, TriggerResponse
    pubCommand = False;
    turtle_vel_pub = rospy.Publisher('/turtle1/cmd_vel', Twist, queue_size=10)
    def command_thread():	
    	while True:
    		if pubCommand:
    			vel_msg = Twist()
    			vel_msg.linear.x = 0.5
    			vel_msg.angular.z = 0.2
    			turtle_vel_pub.publish(vel_msg)			
    		time.sleep(0.1)
    def commandCallback(req):
    	global pubCommand
    	pubCommand = bool(1-pubCommand)
    	# 显示请求数据
    	rospy.loginfo("Publish turtle velocity command![%d]", pubCommand)
    	# 反馈数据
    	return TriggerResponse(1, "Change turtle command state!")
    def turtle_command_server():
    	# ROS节点初始化
        rospy.init_node('turtle_command_server')
    	# 创建一个名为/turtle_command的server，注册回调函数commandCallback
        s = rospy.Service('/turtle_command', Trigger, commandCallback)
    	# 循环等待回调函数
        print "Ready to receive turtle command."
        thread.start_new_thread(command_thread, ())
        rospy.spin()
    if __name__ == "__main__":
        turtle_command_server()

## 2.8 服务数据的定义与使用 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 11]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 12]

*  C+

//客户端

/**
     * 该例程将请求/show_person服务，服务数据类型learning_service::Person
     */
    
    #include <ros/ros.h>
    #include "learning_service/Person.h"
    int main(int argc, char** argv)
    {
        // 初始化ROS节点
    	ros::init(argc, argv, "person_client");
        // 创建节点句柄
    	ros::NodeHandle node;
        // 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
    	ros::service::waitForService("/show_person");
    	ros::ServiceClient person_client = node.serviceClient<learning_service::Person>("/show_person");
        // 初始化learning_service::Person的请求数据
    	learning_service::Person srv; //注意要跟srv的文件名相同
    	srv.request.name = "Tom";
    	srv.request.age  = 20;
    	srv.request.sex  = learning_service::Person::Request::male;
        // 请求服务调用
    	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);
    	// 显示服务调用结果
    	ROS_INFO("Show person result : %s", srv.response.result.c_str());
    	return 0;
    };
    
    
    
    //服务端
    /**
    / * 该例程将执行/show_person服务，服务数据类型learning_service::Person
     */
    #include <ros/ros.h>
    #include "learning_service/Person.h"
    
    // service回调函数，输入参数req，输出参数res
    bool personCallback(learning_service::Person::Request  &req,
             			learning_service::Person::Response &res)
    {
        // 显示请求数据
        ROS_INFO("Person: name:%s  age:%d  sex:%d", req.name.c_str(), req.age, req.sex);
    	// 设置反馈数据
    	res.result = "OK";
        return true;
    }
    int main(int argc, char **argv)
    {
        // ROS节点初始化
        ros::init(argc, argv, "person_server");
        // 创建节点句柄
        ros::NodeHandle n;
        // 创建一个名为/show_person的server，注册回调函数personCallback
        ros::ServiceServer person_service = n.advertiseService("/show_person", personCallback);
        // 循环等待回调函数
        ROS_INFO("Ready to show person informtion.");
        ros::spin();
        return 0;
    }

*  Python

客户端

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将请求/show_person服务，服务数据类型learning_service::Person
    import sys
    import rospy
    from learning_service.srv import Person, PersonRequest
    def person_client():
    	# ROS节点初始化
        rospy.init_node('person_client')
    	# 发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
        rospy.wait_for_service('/show_person')
        try:
            person_client = rospy.ServiceProxy('/show_person', Person)
    		# 请求服务调用，输入请求数据
            response = person_client("Tom", 20, PersonRequest.male)
            return response.result
        except rospy.ServiceException, e:
            print "Service call failed: %s"%e
    if __name__ == "__main__":
    	#服务调用并显示调用结果
        print "Show person result : %s" %(person_client())

服务端
    #!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将执行/show_person服务，服务数据类型learning_service::Person
    import rospy
    from learning_service.srv import Person, PersonResponse
    
    def personCallback(req):
    	# 显示请求数据
        rospy.loginfo("Person: name:%s  age:%d  sex:%d", req.name, req.age, req.sex)
    
    	# 反馈数据
        return PersonResponse("OK")
    
    def person_server():
    	# ROS节点初始化
        rospy.init_node('person_server')
    
    	# 创建一个名为/show_person的server，注册回调函数personCallback
        s = rospy.Service('/show_person', Person, personCallback)
    
    	# 循环等待回调函数
        print "Ready to show person informtion."
        rospy.spin()
    
    if __name__ == "__main__":
        person_server()

## 2.9 参数的使用与编程方法 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 13]  
![在这里插入图片描述][20190717224217125.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 14]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 15]  
![在这里插入图片描述][2019071722514847.png]

*  C++

/**
     * 该例程设置/读取海龟例程中的参数
     */
    #include <string>
    #include <ros/ros.h>
    #include <std_srvs/Empty.h>
    int main(int argc, char **argv)
    {
    	int red, green, blue;
        // ROS节点初始化
        ros::init(argc, argv, "parameter_config");
        // 创建节点句柄
        ros::NodeHandle node;
        // 读取背景颜色参数
    	ros::param::get("/background_r", red);
    	ros::param::get("/background_g", green);
    	ros::param::get("/background_b", blue);
    	ROS_INFO("Get Backgroud Color[%d, %d, %d]", red, green, blue);
    	// 设置背景颜色参数
    	ros::param::set("/background_r", 255);
    	ros::param::set("/background_g", 255);
    	ros::param::set("/background_b", 255);
    	ROS_INFO("Set Backgroud Color[255, 255, 255]");
        // 读取背景颜色参数
    	ros::param::get("/background_r", red);
    	ros::param::get("/background_g", green);
    	ros::param::get("/background_b", blue);
    	ROS_INFO("Re-get Backgroud Color[%d, %d, %d]", red, green, blue);
    	// 调用服务，刷新背景颜色
    	ros::service::waitForService("/clear");
    	ros::ServiceClient clear_background = node.serviceClient<std_srvs::Empty>("/clear");
    	std_srvs::Empty srv;
    	clear_background.call(srv);
    	sleep(1);
        return 0;
    }

![在这里插入图片描述][20190717225410526.png]  
![在这里插入图片描述][20190717225418402.png]

*  Python

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程设置/读取海龟例程中的参数
    import sys
    import rospy
    from std_srvs.srv import Empty
    def parameter_config():
    	# ROS节点初始化
        rospy.init_node('parameter_config', anonymous=True)
    	# 读取背景颜色参数
        red   = rospy.get_param('/background_r')
        green = rospy.get_param('/background_g')
        blue  = rospy.get_param('/background_b')
        rospy.loginfo("Get Backgroud Color[%d, %d, %d]", red, green, blue)
    	# 设置背景颜色参数
        rospy.set_param("/background_r", 255);
        rospy.set_param("/background_g", 255);
        rospy.set_param("/background_b", 255);
        rospy.loginfo("Set Backgroud Color[255, 255, 255]");
    	# 读取背景颜色参数
        red   = rospy.get_param('/background_r')
        green = rospy.get_param('/background_g')
        blue  = rospy.get_param('/background_b')
        rospy.loginfo("Get Backgroud Color[%d, %d, %d]", red, green, blue)
    	#发现/spawn服务后，创建一个服务客户端，连接名为/spawn的service
        rospy.wait_for_service('/clear')
        try:
            clear_background = rospy.ServiceProxy('/clear', Empty)
    		# 请求服务调用，输入请求数据
            response = clear_background()
            return response
        except rospy.ServiceException, e:
            print "Service call failed: %s"%e
    if __name__ == "__main__":
        parameter_config()

## 2.10 tf坐标系广播与监听的编程实现 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 16]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 17]

*  C++  
    广播器的编写

/**
     * 该例程产生tf数据，并计算、发布turtle2的速度指令
     */
    #include <ros/ros.h>
    #include <tf/transform_broadcaster.h>
    #include <turtlesim/Pose.h>
    std::string turtle_name;
    void poseCallback(const turtlesim::PoseConstPtr& msg)
    {
    	// 创建tf的广播器
    	static tf::TransformBroadcaster br;
    	// 初始化tf数据
    	tf::Transform transform;
    	transform.setOrigin( tf::Vector3(msg->x, msg->y, 0.0) );
    	tf::Quaternion q;
    	q.setRPY(0, 0, msg->theta);
    	transform.setRotation(q);
    	// 广播world与海龟坐标系之间的tf数据
    	br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), "world", turtle_name));
    }

int main(int argc, char** argv)
    {
        // 初始化ROS节点
    	ros::init(argc, argv, "my_tf_broadcaster");
    	// 输入参数作为海龟的名字
    	if (argc != 2)
    	{
    		ROS_ERROR("need turtle name as argument"); 
    		return -1;
    	}
    	turtle_name = argv[1];
    	// 订阅海龟的位姿话题
    	ros::NodeHandle node;
    	ros::Subscriber sub = node.subscribe(turtle_name+"/pose", 10, &poseCallback);
        // 循环等待回调函数
    	ros::spin();
    	return 0;
    };

监听器的编写

/**
     * 该例程监听tf数据，并计算、发布turtle2的速度指令
     */
    #include <ros/ros.h>
    #include <tf/transform_listener.h>
    #include <geometry_msgs/Twist.h>
    #include <turtlesim/Spawn.h>
    int main(int argc, char** argv)
    {
    	// 初始化ROS节点
    	ros::init(argc, argv, "my_tf_listener");
        // 创建节点句柄
    	ros::NodeHandle node;
    	// 请求产生turtle2
    	ros::service::waitForService("/spawn");
    	ros::ServiceClient add_turtle = node.serviceClient<turtlesim::Spawn>("/spawn");
    	turtlesim::Spawn srv;
    	add_turtle.call(srv);
    	// 创建发布turtle2速度控制指令的发布者
    	ros::Publisher turtle_vel = node.advertise<geometry_msgs::Twist>("/turtle2/cmd_vel", 10);
    	// 创建tf的监听器
    	tf::TransformListener listener;
    	ros::Rate rate(10.0);
    	while (node.ok())
    	{
    		// 获取turtle1与turtle2坐标系之间的tf数据
    		tf::StampedTransform transform;
    		try
    		{
    			//查询是否有这两个坐标系，查询当前时间，如果超过3s则报错
    			listener.waitForTransform("/turtle2", "/turtle1", ros::Time(0), ros::Duration(3.0));
    			listener.lookupTransform("/turtle2", "/turtle1", ros::Time(0), transform);
    		}
    		catch (tf::TransformException &ex) 
    		{
    			ROS_ERROR("%s",ex.what());
    			ros::Duration(1.0).sleep();
    			continue;
    		}
    		// 根据turtle1与turtle2坐标系之间的位置关系，发布turtle2的速度控制指令
    		geometry_msgs::Twist vel_msg;
    		vel_msg.angular.z = 4.0 * atan2(transform.getOrigin().y(),
    				                        transform.getOrigin().x());
    		vel_msg.linear.x = 0.5 * sqrt(pow(transform.getOrigin().x(), 2) +
    				                      pow(transform.getOrigin().y(), 2));
    		turtle_vel.publish(vel_msg);
    		rate.sleep();
    	}
    	return 0;
    };

![在这里插入图片描述][2019071723204493.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 18]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 19]

--------------------

*  Python

广播器的编写

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将请求/show_person服务，服务数据类型learning_service::Person
    import roslib
    roslib.load_manifest('learning_tf')
    import rospy
    import tf
    import turtlesim.msg
    def handle_turtle_pose(msg, turtlename):
        br = tf.TransformBroadcaster()
        br.sendTransform((msg.x, msg.y, 0),
                         tf.transformations.quaternion_from_euler(0, 0, msg.theta),
                         rospy.Time.now(),
                         turtlename,
                         "world")
    if __name__ == '__main__':
        rospy.init_node('turtle_tf_broadcaster')
        turtlename = rospy.get_param('~turtle')
        rospy.Subscriber('/%s/pose' % turtlename,
                         turtlesim.msg.Pose,
                         handle_turtle_pose,
                         turtlename)
        rospy.spin()

监听器的编写

#!/usr/bin/env python
    # -*- coding: utf-8 -*-
    # 该例程将请求/show_person服务，服务数据类型learning_service::Person
    import roslib
    roslib.load_manifest('learning_tf')
    import rospy
    import math
    import tf
    import geometry_msgs.msg
    import turtlesim.srv
    if __name__ == '__main__':
        rospy.init_node('turtle_tf_listener')
        listener = tf.TransformListener()
        rospy.wait_for_service('spawn')
        spawner = rospy.ServiceProxy('spawn', turtlesim.srv.Spawn)
        spawner(4, 2, 0, 'turtle2')
        turtle_vel = rospy.Publisher('turtle2/cmd_vel', geometry_msgs.msg.Twist,queue_size=1)
        rate = rospy.Rate(10.0)
        while not rospy.is_shutdown():
            try:
                (trans,rot) = listener.lookupTransform('/turtle2', '/turtle1', rospy.Time(0))
            except (tf.LookupException, tf.ConnectivityException, tf.ExtrapolationException):
                continue
            angular = 4 * math.atan2(trans[1], trans[0])
            linear = 0.5 * math.sqrt(trans[0] ** 2 + trans[1] ** 2)
            cmd = geometry_msgs.msg.Twist()
            cmd.linear.x = linear
            cmd.angular.z = angular
            turtle_vel.publish(cmd)
            rate.sleep()

## 2.11 launch启动文件的使用方法 ##

**Launch文件** ：通过XML文件实现多节点的配置和启动（可自动启动ROS Master）  
Launch文件语法：  
![在这里插入图片描述][20190717233024365.png]  
![在这里插入图片描述][20190717233045298.png]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 20]

--------------------

参数设置  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 21]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 22]

--------------------

重映射  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 23]

> 注意，映射完后原资源就不复存在了

--------------------

嵌套  
![在这里插入图片描述][20190717233524574.png]

--------------------

其他：[https://wiki.ros.org/roslaunch/XML][https_wiki.ros.org_roslaunch_XML]

例1：

例2：

例3：

例4：

例5：

## 2.12 常用可视化工具的使用 ##

### 2.12.1 rqt ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 24]

> rqt 是一个比较综合的工具，集成了rqt\_ploat 等一系列的工具，可用于机器人的上位机调试软件

### 2.12.2 Rviz ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 25]

roscore
    rosrun rviz rviz

### 2.12.3 Gazebo ###

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 26]

roslaunch gazebo_ros

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 27]

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 28]

--------------------

番外篇续：

###  ###

## 101.ros打开bag文件 ##

rosbag play path to xxx.bag

例如：

rosbag play ~/Downloads/velodyne.bag

`bag`数据保存命令，请参见：[传送门][Link 1]

###  ###

## 102.ros打开pcap文件 ##

roslaunch velodyne_pointcloud VLP16_points.launch pcap:="path to xxx.pcap"

例如：

roslaunch velodyne_pointcloud VLP16_points.launch pcap:="$HOME/Downloads/velodyne.pcap"

--------------------

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20190717155512600.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/2019071715571784.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzQ1NTU4MQ==,size_16,color_FFFFFF,t_70
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[20190717233524574.png]: https://img-blog.csdnimg.cn/20190717233524574.png
[https_wiki.ros.org_roslaunch_XML]: https://wiki.ros.org/roslaunch/XML
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[Link 1]: https://blog.csdn.net/lovelycrayon/article/details/101209316