ROS+P3DX代码注解 [ 1 ] -- RosAria_client代码注解

首先当拿到源码的时候，应该先从CMakeLists.txt看起来，然后在看对应的源码。

#cmake最小支持的版本cmake_minimum_required(VERSION 2.8.3)#项目的名称project(rosaria_client)#添加一些package的find_package(catkin REQUIRED COMPONENTS  roscpp  rospy  std_msgs  geometry_msgs  rosaria)catkin_package()#包含的子目录include_directories(  ${catkin_INCLUDE_DIRS})## Declare a cpp executable#然后是添加子文件，前面的地方执行文件的名称，后面的是这个cpp的源文件add_executable(go_three_second src/go_three_second.cpp)add_executable(spin_counterclockwise src/spin_counterclockwise.cpp)add_executable(spin_clockwise src/spin_clockwise.cpp)add_executable(teleop src/teleop.cpp)add_executable(print_state src/print_state.cpp)add_executable(interface src/interface.cpp)add_executable(enable_motors src/enable_motors.cpp)#然后就是将每个Cpp文件分别连接库target_link_libraries(go_three_second    ${catkin_LIBRARIES})target_link_libraries(spin_counterclockwise    ${catkin_LIBRARIES})target_link_libraries(spin_clockwise    ${catkin_LIBRARIES})target_link_libraries(teleop    ${catkin_LIBRARIES})target_link_libraries(print_state  ${catkin_LIBRARIES})target_link_libraries(interface  ${catkin_LIBRARIES}  )target_link_libraries(enable_motors  ${catkin_LIBRARIES}  )

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总结：
cmakelists.txt的总体的框架

#cmake最小支持的版本cmake_minimum_required(VERSION 2.8.3)#项目的名称project(rosaria_client)#添加一些package的find_package(catkin REQUIRED COMPONENTS  roscpp)catkin_package()#包含的子目录include_directories(  ${catkin_INCLUDE_DIRS})#然后是添加子文件，前面的地方执行文件的名称，后面的是这个cpp的源文件#add_executable(执行文件的名称 从项目主要目录找到cpp)add_executable(go_three_second src/go_three_second.cpp)#然后就是将每个Cpp文件分别连接库target_link_libraries(go_three_second    ${catkin_LIBRARIES})

enable_motors.cpp：

/*作用：启动电机*/#include <ros/ros.h>int main(int argc, char **argv){//初始化  ros::init(argc, argv, "enable_motors");//实例化一个句柄  ros::NodeHandle nh;//std::system（""）相当于在终端输入后面的指令std::system("rosservice call /RosAria/enable_motors");//对ros进行输入  ROS_INFO_STREAM("Motors are enabled!");  return 0;}

spin_clockwise.cpp:

/*作用：让车旋转45度后停下来（将角速度和线速度都变成0）*/#include<ros/ros.h>#include<geometry_msgs/Twist.h>int main(int argc, char **argv){//初始化  ros::init(argc, argv, "Spin_Clockwise");//实例化句柄  ros::NodeHandle nh;/*补充:发布消息，在RosAria/cmd_vel这个话题上面发布消息，这里的1000就是一个尺度，意义不大（对与初学者而言）发布的消息的数据类型是是genmetry_msgs/Twist我们可以通过什么指令来查看发布的消息的数据类型输入rostopic type 话题名称（例如：/RosAria/cmd_vel）就会返回geometry_msgs/Twist,当然我们一般对cmd_vel的数据类型，都是吧他定义成geometry_msgs/Twist这个数据类型接着，我们可以输入 rosmsg show geometry_msgs/Twist来显示显示出来是三个浮点形，因此在后面是有三数字的，并且有2组是因为一个是线速度，一个角速度同时，我们也可一在终端发布简单的命令，例如：rostopic pub [话题] [数据类型] [参数例如：--'[2 0 0]' '[0 0 0]']*///在句柄nh上发布话题  ros::Publisher pub = nh.advertise<geometry_msgs::Twist>("RosAria/cmd_vel", 1000);//实例化一个geometry_msgs命名空间下的Twist对象，这个对象的名字就叫做msg  geometry_msgs::Twist msg;//设定参数，最开始的速度，运动的时间持续时间，角速度 PI   double BASE_SPEED = 0.2, MOVE_TIME = 3.0, CLOCK_SPEED = 0.5, PI = 3.14159;//判断旋转的  int count = 0;//实例化ros命名空间下的Rate对象，对这个对象的进行初始化，将速度赋值进去  ros::Rate rate(CLOCK_SPEED);  // Make the robot stop (robot perhaps has a speed already) //为了防止意外，让车的初速度设置为0,这里的原始是根据现实出msg 的数据类型  msg.linear.x = 0;  msg.linear.y = 0;  msg.linear.z = 0;  msg.angular.x = 0;  msg.angular.y = 0;  msg.angular.z = 0;  pub.publish(msg);/*ros::ok()这个函数用于当你按下ctrl+c的时候就会返回false，因此经常用于while,或者其他判断语句当中或者当MOVE_TIME/CLOCK_SPEED +1 这个数值不大于0的时候，首先这里是想要旋转6次，然后count的自己+1就，后面这个部分是一个定值，就是说7.那么就让count循环了6次。*/  while(ros::ok() && count<MOVE_TIME/CLOCK_SPEED + 1)  {      // Spin PI/4 /*修改msg.angular.z的数值，根据那个结构，然后发布这个消息，这里的move_time/clock_speed 就是让那他每秒转pi/4的6分一。那么旋转6秒这个旋转的框架还是和厉害的。*/      if (count == 0 || count == 1)        {           msg.angular.z = -1 * PI/ int(MOVE_TIME/CLOCK_SPEED) / 4;           pub.publish(msg);        }      //向屏幕端输出下面的信息      ROS_INFO_STREAM("The robot is now spinning clockwise!");      //然后这里进行自加1      count++;     //调用ros命名空间下的spionOnce()函数，如果这个程序当中有订阅者，那么这条语句就必须存在，为什么在这里写，因为咋这里旋转啊      ros::spinOnce();      //休眠一下，默认是每个1HZ,也就是说1秒刷新一次。也就是说，程序到时候刷新几秒      rate.sleep();  }    // Stop the spin停止旋转，并且将原来的线速度都变成0，并且将速度为0这个消息在发布到msg当中，这里为什么要用一个for语句循环两侧，我就不知道了  for(int i = 0; i < 2; i++)  {      msg.angular.x = 0;      msg.angular.y = 0;      msg.angular.z = 0;      pub.publish(msg);  }  //输出辅助信息    ROS_INFO_STREAM("The robot finished spinning 45 degrees!");   // Guard, make sure the robot stops保证这个时候的线速度也是0,并且进行过发布   rate.sleep();   msg.linear.x = 0;   msg.linear.y = 0;   msg.linear.z = 0;   pub.publish(msg);}

teleop.cpp:

/*功能：实现箭头控制，以及ctrl+c表示暂停*/#include <ros/ros.h>#include <geometry_msgs/Twist.h>#include <signal.h>#include <termios.h>#include <stdio.h>/*箭头和16进制的对应关系*/#define KEYCODE_R 0x43 //右#define KEYCODE_L 0x44 //左#define KEYCODE_U 0x41 //上#define KEYCODE_D 0x42 //下#define KEYCODE_Q 0x71 //停止#define KEYCODE_SPACE 0x20 //空格/*TeleopRosAria的功能*/class TeleopRosAria{  public:    TeleopRosAria();//函数功能：函数发布消息，并且给句柄赋值    void keyLoop();  private:    ros::NodeHandle nh_;//    double linear_, angular_, l_scale_, a_scale_;    ros::Publisher twist_pub_;};TeleopRosAria::TeleopRosAria():  linear_(0),  angular_(0),  l_scale_(2.0),  a_scale_(2.0){//这个param给scale_angular附上初始值  nh_.param("scale_angular", a_scale_, a_scale_);  nh_.param("scale_linear", l_scale_, l_scale_);//发布一个话题，并且设置队列的长度是1  twist_pub_ = nh_.advertise<geometry_msgs::Twist>("RosAria/cmd_vel", 1);}//这是帧率int kfd = 0;//定义结构体struct termios cooked, raw;/*补充：这个函数包含在 termios.h头文件中tcsetarr(int fd, int optional_action,const struct)函数用于设置终端参数另外const * 在使用的时候，就是& 一一对应就好参数列表： fd 是帧率 optional_action用于控制修改起作用的时间 strcut保存要修改的参数option_action:TCSANOW：不等待数据传输完毕就立即改变属性*//*暂停函数，全局函数*/void quit(int sig){  tcsetattr(kfd, TCSANOW, &cooked);  ros::shutdown();//如果按下ctrl+c立即退出  exit(0);}//函数主线程的入口int main(int argc, char** argv){  ros::init(argc, argv, "teleop_RosAria");  TeleopRosAria teleop_RosAria;/*补充：signal()函数在头文件 signal.h中，signal(参数1,参数2)参数1:我们要进行处理的信信号参数2:我们要处理的方式SIGINT是由于interrupt Key产生quit是一个全局函数*///设置某一个信号对应的动作，这里设置的应该是强制结束的动作。  signal(SIGINT,quit);//调用keyloop函数  teleop_RosAria.keyLoop();  return(0);}//功能：键盘控制void TeleopRosAria::keyLoop(){  char c;  bool dirty=false;  // get the console in raw mode 得到控制的初始模型/*补充：tcgetattr函数在termios.h头文件中，用于获取终端的相关参数 kdf是一个全局变量memcpy函数在string.h文件中，用于从src指定的位置拷贝N个字节到目标dest所指的内存地址的起始的位置memcpy(src,dest,n) raw是一个结构体，表示：结构体的c_flag表示本地模式标志说明：ICANON说明是启动标准模式ECHO应该受到一个ERASE控制符的时候删除前一个显示符号，我觉着这个地方是为了箭头做准备的保护机制。*/  tcgetattr(kfd, &cooked);  memcpy(&raw, &cooked, sizeof(struct termios));  raw.c_lflag &=~ (ICANON | ECHO);  // Setting a new line, then end of file 在文件后面设置一个新的线程/*c_cc[VEOF]默认的控制符号 D，在标准模式下，使用read()返回0 ,标志一个文件结束c_cc[VEOL]在行尾加上一个换行符号（"\n"）标志一个行的结束，重新开始一行*/  raw.c_cc[VEOL] = 1;  raw.c_cc[VEOF] = 2;  tcsetattr(kfd, TCSANOW, &raw);//输出辅助信息  puts("Reading from keyboard");  puts("---------------------------");  puts("Use arrow keys to move the robot.");  puts("Press the space bar to stop the robot.");  puts("Press q to stop the program");//死循环  for(;;)  {    // get the next event from the keyboard 从键盘得到下一个事件    if(read(kfd, &c, 1) < 0)      {      perror("read():");//将上一个函数发生错误的原因输出到设备参数中      exit(-1);      }//线速度的角度速度为0    linear_=angular_=0;//信息在程序中运行不直接显示到终端上    ROS_DEBUG("value: 0x%02X\n", c);//箭头控制    switch(c)      {        case KEYCODE_L:          ROS_DEBUG("LEFT");          angular_ = 0.1;          linear_ = 0;          dirty = true;          break;        case KEYCODE_R:          ROS_DEBUG("RIGHT");          angular_ = -0.1;          linear_ = 0;          dirty = true;          break;        case KEYCODE_U:          ROS_DEBUG("UP");          linear_ = 0.1;          angular_ = 0;          dirty = true;          break;        case KEYCODE_D:          ROS_DEBUG("DOWN");          linear_ = -0.1;          angular_ = 0;          dirty = true;          break;        case KEYCODE_SPACE:          ROS_DEBUG("STOP");          linear_ = 0;          angular_ = 0;          dirty = true;          break;      case KEYCODE_Q:        ROS_DEBUG("QUIT");        ROS_INFO_STREAM("You quit the teleop successfully");        return;        break;    }    //实例化对象    geometry_msgs::Twist twist;    //这个里面angular里面肯定是有继承关系的    twist.angular.z = a_scale_*angular_;    twist.linear.x = l_scale_*linear_;    //    if(dirty ==true)    {    /*    只是发布一次消息    */      twist_pub_.publish(twist);      dirty=false;    }  }  //return 相当与break吧  return;}

print_state.cpp：

/*功能：输出先锋机器人状态的信息*/#include <ros/ros.h>#include <std_msgs/Float32.h>#include <std_msgs/Float64.h>#include <std_msgs/Int8.h>#include <std_msgs/Bool.h>#include <nav_msgs/Odometry.h>#include <rosaria/BumperState.h>#include <iomanip> // for std :: setprecision and std :: fixedint battery_msg_count = 0, bumper_msg_count = 0;//初始化保险杠的距离和电池的状态/*补充：setprecision 控制输出流显示的浮点数的有效数字的个数（会有四舍五入） 需要加入头文件iomanip.hstd::fix表示用一般的方式输出浮点数*//* checks pose messages and outputs them to user 输出当前位置的和角度，用浮点数输出*/void poseMessageReceived(const nav_msgs::Odometry& msg) {    std::cout << std::setprecision(2) << std::fixed << /* output the pose information using standard output */      "Current position=(" << msg.pose.pose.position.x << ", " << msg.pose.pose.position.y << ") " <<       "Current direction=" << std::setprecision(2) << std::fixed << msg.pose.pose.orientation.w<<"\r";      std::flush(std::cout);}/* output the state of the bumpers using rosaria 使出保险杠的状态*/void bumperStateMessageReceived(const rosaria::BumperState &msg)//这个地方是一个形参{    int front_size, rear_size; //定义前面的距离和后面的剧烈       if (bumper_msg_count == 0)    {//      ROS_INFO_STREAM("The front bumpers are "<<msg.front_bumpers<<std::endl<<"The rear bumpers are "<<msg.rear_bumpers);        front_size = sizeof(msg.front_bumpers) / sizeof(bool);        rear_size = sizeof(msg.rear_bumpers) / sizeof(bool);        ROS_INFO_STREAM("The front bumpers state are('1' means good): ");//输出辅助信息      std::cout << "    ";        for (int i=0;i<front_size;i++)      if (msg.front_bumpers[i])            std::cout<<'1';      else        std::cout<<'0';//换行        std::cout<<std::endl;        ROS_INFO_STREAM("The rear bumpers state are('1' means good): ");      std::cout << "    ";        for (int i=0;i<rear_size;i++)      if (msg.rear_bumpers[i])        std::cout<<'1';      else        std::cout<<'0';        std::cout<<std::endl;        bumper_msg_count++;    }}/* check the status of the battery charge 检查电池的状态 分别对应msg的类型，然后输出就可以啦*/void batteryStateOfChargeMessageReceived(const std_msgs::Float32 msg){    // Right now this feature is not included in the pioneer-3 robot        ROS_INFO_STREAM("The battery state of charge is "<<msg);}/* check + output the voltage of the battery using standard output 检查电压的状态 */void batteryVoltageMessageReceived(const std_msgs::Float64 msg){      if (battery_msg_count == 0)    {      battery_msg_count++;      ROS_INFO_STREAM("The battery voltage is "<< msg);    }}void batteryChargeStateMessageReceived(const std_msgs::Int8 msg){    // Right now this feature is not included in the pioneer-3 robot    ROS_INFO_STREAM("The battery charge state message received is "<< msg);}/* check the state of the motor and output using standard output 检查发动机的状态*/void motorsStateMessageReceived(const std_msgs::Bool msg){    if (msg.data)        ROS_INFO_STREAM("The motor is good");    else        ROS_INFO_STREAM("The motor is bad");}/* call all of the functions implemented above and provide user with robot state info */int main(int argc, char **argv){    // Initialize the ROS system and become a node.初始化    ros::init(argc, argv, "print_aria_state"); ros::NodeHandle nh;    // Create a subscriber object .    //就爱嗯这个订阅各自的话题    ros::Subscriber pose, bumper_state, battery_state_of_charge, battery_voltage, battery_charge_state, motors_state;    pose = nh.subscribe("RosAria/pose", 1000, &poseMessageReceived) ; //supply pose    bumper_state = nh.subscribe("RosAria/bumper_state", 1000, &bumperStateMessageReceived) ; //inform bumper state    battery_state_of_charge = nh.subscribe("RosAria/bumper_state_of_charge", 1000, &batteryStateOfChargeMessageReceived) ; //inform state of charge    battery_voltage = nh.subscribe("RosAria/battery_voltage", 1000, &batteryVoltageMessageReceived) ; //inform battery voltage level    battery_charge_state = nh.subscribe("RosAria/battery_charge_state", 1000, &batteryChargeStateMessageReceived) ; //inform charge state    motors_state = nh.subscribe("RosAria/motors_state", 1000, &motorsStateMessageReceived) ; //inform motor state    // Let ROS take over.悬停     ros::spin(); }

RosAria_client.launch文件

<launch>    <node pkg = "rosaria" type = "RosAria" name = "RosAria">        <param name="port" value="/dev/ttyUSB0" type="string"/>    </node>    <node pkg="rosaria_client" type="interface" name="RosAria_interface" output="screen"/></launch>

在launch文件中添加节点和节点名称，以及对一些参数的修改