Chapter2：ROS基础

${\rm ROS1}$ 的基础及应用，基于古月的课，各位可以去看，基于 ${\rm hawkbot}$ 机器人进行实际操作。
${\rm ROS}$ 版本： ${\rm ROS1}$ 的 ${\rm Melodic}$ ；实际机器人： ${\rm Hawkbot}$ ；

1.创建工作空间

工作空间

工作空间 $({\rm workspace})$ 是一个存放工程开发相关文件的文件夹。
- ${\rm src}$ ：代码空间 $({\rm Source\ Space})$ ；
- ${\rm build}$ ：编译空间 $({\rm Build\ Space})$ ；
- ${\rm devel}$ ：开发空间 $({\rm Development\ Space})$ ；
- ${\rm install}$ ：安装空间 $({\rm Install\ Space})$ ；
工作空间目录树结构示例：
```
tree -L 2 catkin_ws/
===============================================================================
catkin_ws/
├── build
│   ├── atomic_configure
│   ├── catkin
│   ├── catkin_generated
│   ├── CATKIN_IGNORE
│   ├── catkin_make.cache
│   ├── CMakeCache.txt
│   ├── CMakeFiles
│   ├── cmake_install.cmake
│   ├── CTestConfiguration.ini
│   ├── CTestCustom.cmake
│   ├── CTestTestfile.cmake
│   ├── gtest
│   ├── hawkbot
│   ├── hawkbot_applications
│   ├── line_follower_turtlebot
│   ├── Makefile
│   ├── orb_slam_2_ros
│   └── test_results
├── devel
│   ├── cmake.lock
│   ├── env.sh
│   ├── include
│   ├── lib
│   ├── local_setup.bash
│   ├── local_setup.sh
│   ├── local_setup.zsh
│   ├── setup.bash
│   ├── setup.sh
│   ├── _setup_util.py
│   ├── setup.zsh
│   └── share
└── src
    ├── CMakeLists.txt -> /opt/ros/melodic/share/catkin/cmake/toplevel.cmake
    ├── hawkbot
    ├── hawkbot_applications
    └── orb_slam_2_ros
===============================================================================
```

创建工作空间

# 1.创建工作空间
mkdir -p ~/willard_ws/src
cd ~/willard_ws/src
catkin_init_workspace

# 2.编译工作空间
cd ~/willard_ws/
catkin_make

# 3.设置环境变量
source devel/setup.sh
vim ~/.bashrc
source ~/.bashrc

# 4.检查环境变量
echo $ROS_PACKAGE_PATH

# 由于原来存在一个工作空间，因此使用echo命令输出如下：
# /home/hawkbot/willard_ws/src:/home/hawkbot/catkin_ws/src:/opt/ros/melodic/share

创建功能包

# 语法：catkin_create_pkg <pkg_name> [depend1] [depend2]..
# 1.创建功能包
cd ~/willard_ws/src
catkin_create_pkg learning_communication std_msgs rospy roscpp

# 2.编译功能包
cd ~/willard_ws
catkin_make
source ~/willard_ws/devel/setup.bash

# 注意：同一个工作空间下，不允许存在同名功能包，不同工作空间下，允许存在同名功能包；

工作空间覆盖机制
- 工作空间的路径依次在 ${\rm ROS\_PACKAGE\_PATH}$ 环境变量中记录；
- 新设置的路径在 ${\rm ROS\_PACKAGE\_PATH}$ 中自动放在最前端；
- 运行时， ${\rm ROS}$ 优先查找最前端的工作空间中是否存在指定的功能包；
- 如果不存在，就顺序向后查找其他工作空间；
```
# 查看关于ros的所有环境变量
env | grep ros

# 实践中的结果
ROS_PACKAGE_PATH=/home/hawkbot/willard_ws/src:/home/hawkbot/catkin_ws/src:/opt/ros/melodic/share

# 可见ROS_PACKAGE_PATH存在三个工作空间的环境变量
# 执行顺序依次为：willard_ws、catkin_ws
```

2.ROS通信编程

2.1 话题通信编程

创建发布者；
创建订阅者；
添加编译选项；
运行可执行程序；

2.1.1 发布者编程实现

初始化 ${\rm ROS}$ 节点；
向 ${\rm ROS\ Master}$ 注册节点信息，包括：发布的话题名和话题中的消息类型；
按照一定频率循环发布消息；

编程实现：

// talker.cpp文件

/**
 *  该例程将发布chatter话题，消息类型为String
*/

#include <sstream>
#include "ros/ros.h"
#include "std_msgs/String.h"

int main(int argc, char  **argv)
{
    // 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 << "Hello.Welcome to FUXI.Technology." << 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();

        // 按照循环频率延时
        loop_rate.sleep();
        ++count;
    }

    return 0;
    
}

2.1.2 订阅者编程实现

初始化 ${\rm ROS}$ 节点；
订阅需要的话题；
循环等待话题消息，接收到消息后进入回调函数；
在回调函数中完成消息处理；

编程实现：

// listener.cpp文件

/**
 *  该例程将订阅chatter话题，消息类型为String
*/

#include "ros/ros.h"
#include  "std_msgs/String.h"

// 接收到订阅的消息后，进入消息回调函数
void chatterCallback(const std_msgs::String::ConstPtr& msg)
{
    // 打印接收到的消息
    ROS_INFO("I heard: [%s]", msg->data.c_str());
}

int main(int argc, char **argv)
{
    // 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;
}

2.1.3 编译代码

设置需要编译的代码和生成的可执行文件；
设置链接库；
设置依赖；

具体实现在 ${\rm learning_communication/CMakeLists.txt}$ 文件：

cmake_minimum_required(VERSION 2.8.3)
project(learning_communication)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
)

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )

## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )

## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here
# generate_messages(
#   DEPENDENCIES
#   std_msgs
# )

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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_communication
#  CATKIN_DEPENDS roscpp rospy std_msgs
#  DEPENDS system_lib
)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_communication.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_communication_node.cpp)

# 新增加的链接库和依赖
# ---------------------------------------------------
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
# ---------------------------------------------------

## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_communication.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

# 1.编写发布者talker.cpp
# 2.编写订阅者listener.cpp
# 3.在CMakeLists.txt文件中设置链接库和依赖；
# 4.切换到工作空间进行编译；
cd ~/Willard_ws/
catkin_make
# 5.运行可执行文件，注：没有.cpp后缀；
roscore
rosrun learning_communication talker
rosrun learning_communication listener

# 注意：代码文件放在功能包learning_communication/src下；
# 设置链接库和依赖是在learning_communication/CMakeLists.txt；

实现效果如下：

2.1.4 自定义话题消息

# 1.在learning_communication目录下新建msg目录
mkdir msg

# 2.定义msg文件；
# Person.msg
string name
uint8 sex
uint8 age

uint8 unknown = 0
uint8 male = 1
uint8 female = 2

# 3.在package.xml中添加功能包依赖
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>

# 4.在CMakeLists.txt添加编译选项
find_package(... message_generation)
catkin_package(CATKIN_DEPENDS roscpp rospy std_msgs message_runtime)
add_message_files(FILES Person.msg)
generate_messages(DEPENDENCIES std_msgs)

# 5.编译
cd ~/willard_ws/
catkin_make

# 6.编译成功后，查看Person.msg信息
rosmsg show Person

# Person.msg
string name
uint8 sex
uint8 age

uint8 unknown = 0
uint8 male = 1
uint8 female = 2

<!-- packages.xml -->

<?xml version="1.0"?>
<package format="2">
  <name>learning_communication</name>
  <version>0.0.0</version>
  <description>The learning_communication package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="hawkbot@todo.todo">hawkbot</maintainer>


  <!-- One license tag required, multiple allowed, one license per tag -->
  <!-- Commonly used license strings: -->
  <!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
  <license>TODO</license>


  <!-- Url tags are optional, but multiple are allowed, one per tag -->
  <!-- Optional attribute type can be: website, bugtracker, or repository -->
  <!-- Example: -->
  <!-- <url type="website">http://wiki.ros.org/learning_communication</url> -->


  <!-- Author tags are optional, multiple are allowed, one per tag -->
  <!-- Authors do not have to be maintainers, but could be -->
  <!-- Example: -->
  <!-- <author email="jane.doe@example.com">Jane Doe</author> -->


  <!-- The *depend tags are used to specify dependencies -->
  <!-- Dependencies can be catkin packages or system dependencies -->
  <!-- Examples: -->
  <!-- Use depend as a shortcut for packages that are both build and exec dependencies -->
  <!--   <depend>roscpp</depend> -->
  <!--   Note that this is equivalent to the following: -->
  <!--   <build_depend>roscpp</build_depend> -->
  <!--   <exec_depend>roscpp</exec_depend> -->
  <!-- Use build_depend for packages you need at compile time: -->
  <!--   <build_depend>message_generation</build_depend> -->
  <!-- Use build_export_depend for packages you need in order to build against this package: -->
  <!--   <build_export_depend>message_generation</build_export_depend> -->
  <!-- Use buildtool_depend for build tool packages: -->
  <!--   <buildtool_depend>catkin</buildtool_depend> -->
  <!-- Use exec_depend for packages you need at runtime: -->
  <!--   <exec_depend>message_runtime</exec_depend> -->
  <!-- Use test_depend for packages you need only for testing: -->
  <!--   <test_depend>gtest</test_depend> -->
  <!-- Use doc_depend for packages you need only for building documentation: -->
  <!--   <doc_depend>doxygen</doc_depend> -->
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>

  <!-- 新增的依赖 -->
  <build_depend>message_generation</build_depend>
  <exec_depend>message_runtime</exec_depend>


  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->

  </export>
</package>

# CMakeLists.txt文件

cmake_minimum_required(VERSION 2.8.3)
project(learning_communication)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages

# =============================================
# 新增message_generation
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
)
# =============================================

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder

# =============================================
# 新增内容的位置
add_message_files(
    FILES
    Person.msg
#   Message1.msg
#   Message2.msg
)
# =============================================

## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )

## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here

# =============================================
# 新增内容的位置
generate_messages(
    DEPENDENCIES
    std_msgs
)
# =============================================

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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

# =============================================
# 需要新增内容的位置
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES learning_communication
   CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
#  DEPENDS system_lib
)
# =============================================

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_communication.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_communication_node.cpp)

# 新增加的链接库和依赖
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)


## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_communication.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

2.2 服务通信编程

创建服务器；
创建客户端；
添加编译选项；
运行可执行文件；

2.2.1 自定义服务请求与应答

# 1.定义srv文件，放置在learning_communication/srv目录下
roscd learning_communication/
mkdir srv
cd srv

# 2.定义Add.srv文件
gedit Add.srv

# 3.在package.xml中添加功能包依赖
<build_depend>message_generation</build_depend>
<exec_depend>message_runtime</exec_depend>

# 4.在CMakeLists.txt添加编译选项
find_package(... message_generation)
catkin_package(CATKIN_DEPENDS roscpp rospy std_msgs message_runtime)
add_service_files(FILES Add.srv)

# 5.编译
cd ~/willard_ws/
catkin_make

# 注：自定义服务过程和自定义消息过程类似；

# Add.srv文件
int64 a
int64 b
int64 c
---
int64 sum

<!-- packages.xml文件 -->

<?xml version="1.0"?>
<package format="2">
  <name>learning_communication</name>
  <version>0.0.0</version>
  <description>The learning_communication package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="hawkbot@todo.todo">hawkbot</maintainer>


  <!-- One license tag required, multiple allowed, one license per tag -->
  <!-- Commonly used license strings: -->
  <!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
  <license>TODO</license>


  <!-- Url tags are optional, but multiple are allowed, one per tag -->
  <!-- Optional attribute type can be: website, bugtracker, or repository -->
  <!-- Example: -->
  <!-- <url type="website">http://wiki.ros.org/learning_communication</url> -->


  <!-- Author tags are optional, multiple are allowed, one per tag -->
  <!-- Authors do not have to be maintainers, but could be -->
  <!-- Example: -->
  <!-- <author email="jane.doe@example.com">Jane Doe</author> -->


  <!-- The *depend tags are used to specify dependencies -->
  <!-- Dependencies can be catkin packages or system dependencies -->
  <!-- Examples: -->
  <!-- Use depend as a shortcut for packages that are both build and exec dependencies -->
  <!--   <depend>roscpp</depend> -->
  <!--   Note that this is equivalent to the following: -->
  <!--   <build_depend>roscpp</build_depend> -->
  <!--   <exec_depend>roscpp</exec_depend> -->
  <!-- Use build_depend for packages you need at compile time: -->
  <!--   <build_depend>message_generation</build_depend> -->
  <!-- Use build_export_depend for packages you need in order to build against this package: -->
  <!--   <build_export_depend>message_generation</build_export_depend> -->
  <!-- Use buildtool_depend for build tool packages: -->
  <!--   <buildtool_depend>catkin</buildtool_depend> -->
  <!-- Use exec_depend for packages you need at runtime: -->
  <!--   <exec_depend>message_runtime</exec_depend> -->
  <!-- Use test_depend for packages you need only for testing: -->
  <!--   <test_depend>gtest</test_depend> -->
  <!-- Use doc_depend for packages you need only for building documentation: -->
  <!--   <doc_depend>doxygen</doc_depend> -->
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>

  <!-- 新增的依赖 -->
  <build_depend>message_generation</build_depend>
  <exec_depend>message_runtime</exec_depend>


  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->

  </export>
</package>

# CMakeLists.txt文件
cmake_minimum_required(VERSION 2.8.3)
project(learning_communication)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages

# =============================================
# 新增message_generation
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
)
# =============================================

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder

# =============================================
# 新增内容的位置
add_message_files(
    FILES
    Person.msg
#   Message1.msg
#   Message2.msg
)
# =============================================

## Generate services in the 'srv' folder

# =============================================
# 新增内容的位置
add_service_files(
    FILES
    Add.srv
#   Service1.srv
#   Service2.srv
)
# =============================================

## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here

# =============================================
# 新增内容的位置
generate_messages(
    DEPENDENCIES
    std_msgs
)
# =============================================

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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

# =============================================
# 需要新增内容的位置
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES learning_communication
   CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
#  DEPENDS system_lib
)
# =============================================

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_communication.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_communication_node.cpp)

# 新增加的链接库和依赖
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)


## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_communication.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

2.2.2 服务器编程实现

初始化 ${\rm ROS}$ 节点；
创建 ${\rm Server}$ 实例；
循环等待服务请求，进入回调函数；
在回调函数中完成服务功能的处理，并反馈应答数据；

服务器编程实现：

/**
 * Add Server
 */

#include "ros/ros.h"
#include "learning_communication/Add.h"

// service回调函数，输入参数req，输出参数res
bool add(learning_communication::Add::Request &req,
         learning_communication::Add::Response &res)
{
    // 将输入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 + req.c;
    ROS_INFO("request: x=%ld, y=%ld,z=%ld", (long int)req.a, (long int)req.b, (long int)req.c);
    ROS_INFO("sending back response: [%ld]", (long int)res.sum);

    return true;
}

int main(int argc, char **argv)
{
    // ROS节点初始化
    ros::init(argc, argv, "add_server");

    // 创建节点句柄
    ros::NodeHandle n;

    // 创建一个名为add_three_ints的server，注册回调函数add()
    ros::ServiceServer service = n.advertiseService("add_three_ints", add);

    // 循环等待回调函数
    ROS_INFO("Ready to add three ints.");
    ros::spin();

    return 0;
}

2.2.3 客户端编程实现

初始化 ${\rm ROS}$ 节点；
创建一个 ${\rm Client}$ 实例；
发布服务请求数据；
等待 ${\rm Server}$ 处理后的应答结果；

客户端编程实现：

/**
 *  Add client
 */

#include <cstdlib>
#include "ros/ros.h"
#include "learning_communication/Add.h"

int main(int argc, char **argv)
{
    // ROS节点初始化
    ros::init(argc, argv, "add_client");

    // 从终端命令行获取三个加数
    if (argc != 4)
    {
        ROS_INFO("usage: add_client X Y Z");
        return 1;
    }

    // 创建节点句柄
    ros::NodeHandle n;

    // 创建一个client，请求add service，service消息类型是learning_communication::Add;
    ros::ServiceClient client = n.serviceClient<learning_communication::Add>("add_three_ints");     // 注意和server注册的服务名一致

    // 创建learning_communication::Add类型的service消息
    learning_communication::Add srv;
    srv.request.a = atoll(argv[1]);
    srv.request.b = atoll(argv[2]);
    srv.request.c = atoll(argv[3]);

    // 发布service请求，等待加法运算的应答结果
    if (client.call(srv))
    {
        ROS_INFO("Sum: %ld", (long int)srv.response.sum);
    }
    else
    {
        ROS_ERROR("Failed to call service add_three_ints");
        return 1;
    }

    return 0;
}

2.2.4 编译代码

设置需要编译的代码和生成的可执行文件；
设置链接库；
设置依赖；

具体实现：

# CMakeLists.txt对应位置添加如下内容
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)

服务建立过程：

# 1.定义服务的请求与应答文件；
# 2.编写服务器端代码；
# 3.编写客户端代码；
# 4.设置需要编译的代码和生成的可执行文件，设置链接库，设置依赖；
# 5.工作空间下编译；
cd ~/willard_ws/
catkin_make

# 6.运行可执行文件
roscore		# 启动master
rosrun learning_communication server
rosrun learning_commnuication client 1 2 3

实现效果图：

2.3 动作通信编程

2.3.1 动作通信机制基础

动作 $({\rm action})$ 的定义
- 一种问答通信机制；
- 带有连续反馈；
- 可以在任务过程中止运行；
- 基于 ${\rm ROS}$ 的消息机制实现；
- 动作 $({\rm action})$ 通信机制：
${\rm Action}$ 接口定义
- ${\rm goal}$ ：发布任务目标；
- ${\rm cancel}$ ：请求取消任务；
- ${\rm status}$ ：通知客户端当前的状态；
- ${\rm feedback}$ ：周期反馈任务运行的监控数据；
- ${\rm result}$ ：向客户端发送任务的执行结果，只发布一次；
- 示意图如下：

2.3.2 自定义动作消息

# 1.定义action文件；
# DoDishes.action
------------------------------
# 定义目标信息
uint32 dishwasher_id
---
# 定义结果信息
uint32 total_dishes_cleaned
---
# 定义周期反馈的消息
float32 percent_complete
------------------------------

# 2.在package.xml中添加功能包依赖；
<build_depend>actionlib</build_depend>
<build_depend>actionlib_msgs</build_depend>
<exec_depend>actionlib</exec_depend>
<exec_depend>actionlib_msgs</exec_depend>

# 3.在CMakeLists.txt添加编译选项
# 注意：在原来的文件中加入一些依赖即可，不用另起一行重新加入这些信息；
# 直接找到find_package(...actionlib_msgs actionlib)
find_package(catkin REQUIRED actionlib_msgs actionlib)
add_action_files(DIRECTORY action FILES DoDishes.action)
generate_messages(DEPENDENCIES actionlib_msgs)

# 1.创建action目录
roscd learning_communication/
mkdir action

# 2.定义.action文件
cd action
touch DoDishes.action
gedit DoDishes.action

# 3.在package.xml中添加功能包依赖
gedit package.xml

# 4.在CMakeLists.txt文件添加编译选项
gedit CMakeLists.txt

# 5.编译
cd ~/willard_ws/
catkin_make

# DoDishes.action文件
# 注意.action文件的定义格式

# 定义目标信息
uint32 dishwasher_id
---
# 定义结果信息
uint32 total_dishes_cleaned
---
# 定义周期反馈消息
float32 percent_complete

<!-- package.xml文件 -->

<?xml version="1.0"?>
<package format="2">
  <name>learning_communication</name>
  <version>0.0.0</version>
  <description>The learning_communication package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="hawkbot@todo.todo">hawkbot</maintainer>


  <!-- One license tag required, multiple allowed, one license per tag -->
  <!-- Commonly used license strings: -->
  <!--   BSD, MIT, Boost Software License, GPLv2, GPLv3, LGPLv2.1, LGPLv3 -->
  <license>TODO</license>


  <!-- Url tags are optional, but multiple are allowed, one per tag -->
  <!-- Optional attribute type can be: website, bugtracker, or repository -->
  <!-- Example: -->
  <!-- <url type="website">http://wiki.ros.org/learning_communication</url> -->


  <!-- Author tags are optional, multiple are allowed, one per tag -->
  <!-- Authors do not have to be maintainers, but could be -->
  <!-- Example: -->
  <!-- <author email="jane.doe@example.com">Jane Doe</author> -->


  <!-- The *depend tags are used to specify dependencies -->
  <!-- Dependencies can be catkin packages or system dependencies -->
  <!-- Examples: -->
  <!-- Use depend as a shortcut for packages that are both build and exec dependencies -->
  <!--   <depend>roscpp</depend> -->
  <!--   Note that this is equivalent to the following: -->
  <!--   <build_depend>roscpp</build_depend> -->
  <!--   <exec_depend>roscpp</exec_depend> -->
  <!-- Use build_depend for packages you need at compile time: -->
  <!--   <build_depend>message_generation</build_depend> -->
  <!-- Use build_export_depend for packages you need in order to build against this package: -->
  <!--   <build_export_depend>message_generation</build_export_depend> -->
  <!-- Use buildtool_depend for build tool packages: -->
  <!--   <buildtool_depend>catkin</buildtool_depend> -->
  <!-- Use exec_depend for packages you need at runtime: -->
  <!--   <exec_depend>message_runtime</exec_depend> -->
  <!-- Use test_depend for packages you need only for testing: -->
  <!--   <test_depend>gtest</test_depend> -->
  <!-- Use doc_depend for packages you need only for building documentation: -->
  <!--   <doc_depend>doxygen</doc_depend> -->
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>

  <!-- 新增的依赖 -->
  <build_depend>message_generation</build_depend>
  <exec_depend>message_runtime</exec_depend>

  <!-- action新增的依赖 -->
  <build_depend>actionlib</build_depend>
  <build_depend>actionlib_msgs</build_depend>
  <exec_depend>actionlib</exec_depend>
  <exec_depend>actionlib_msgs</exec_depend>


  <!-- The export tag contains other, unspecified, tags -->
  <export>
    <!-- Other tools can request additional information be placed here -->

  </export>
</package>

# CMakeLists.txt文件

cmake_minimum_required(VERSION 2.8.3)
project(learning_communication)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages

# =============================================
# 新增message_generation
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
  # ==action新增依赖==
  actionlib_msgs
  actionlib
  # ==================
)
# =============================================

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder

# =============================================
# 新增内容的位置
add_message_files(
    FILES
    Person.msg
#   Message1.msg
#   Message2.msg
)
# =============================================

## Generate services in the 'srv' folder

# =============================================
# 新增内容的位置
add_service_files(
    FILES
    Add.srv
#   Service1.srv
#   Service2.srv
)
# =============================================

## Generate actions in the 'action' folder

# =======================================================
# action新增内容的位置
add_action_files(
    FILES
    DoDishes.action
#   Action1.action
#   Action2.action
)
# =======================================================

## Generate added messages and services with any dependencies listed here

# =============================================
# 新增内容的位置
generate_messages(
    DEPENDENCIES
    std_msgs
    actionlib_msgs
)
# =============================================

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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

# =============================================
# 需要新增内容的位置
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES learning_communication
   CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
#  DEPENDS system_lib
)
# =============================================

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_communication.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_communication_node.cpp)

# 新增加的链接库和依赖
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)

# ==================================================
# 服务新增加的依赖
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)
# ==================================================


## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_communication.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

2.3.3 动作服务器编程实现

初始化 ${\rm ROS}$ 节点；
创建动作服务器实例；
启动服务器，等待动作请求；
在回调函数中完成动作功能的处理，并反馈进度信息；
动作完成，发送结束信息；

动作服务器编程实现：

#include <ros/ros.h>
#include <actionlib/server/simple_action_server.h>
#include "learning_communication/DoDishesAction.h"

typedef actionlib::SimpleActionServer<learning_communication::DoDishesAction> Server;

// 收到action的goal后调用该回调函数
void execute(const learning_communication::DoDishesGoalConstPtr& goal, Server* as)
{
    ros::Rate r(1);
    learning_communication::DoDishesFeedback feedback;

    ROS_INFO("Dishwasher %d is working.", goal->dishwasher_id);

    // 假设洗盘子的进度，并且按照1hz的频率发布进度feedback
    for(int i=1; i<=10; i++)
    {
        feedback.percent_complete = i * 10;
        as->publishFeedback(feedback);
        r.sleep();
    }

    // 当action完成后，向客户端返回结果
    ROS_INFO("Dishwasher %d finish working.", goal->dishwasher_id);
    as->setSucceeded();
}

int main(int argc, char** argv)
{
    ros::init(argc, argv, "do_dishes_server");
    ros::NodeHandle n;

    // 定义一个服务器
    Server server(n, "do_dishes", boost::bind(&execute, _1, &server), false);
    
    // 服务器开始运行
    server.start();

    ros::spin();

    return 0;
}

2.3.4 动作客户端编程实现

初始化 ${\rm ROS}$ 节点；
创建动作客户端实例；
连接动作服务端；
发动动作目标；
根据不同类型的服务端反馈处理回调函数；

动作客户端编程实现：

#include <actionlib/client/simple_action_client.h>
#include "learning_communication/DoDishesAction.h"

typedef actionlib::SimpleActionClient<learning_communication::DoDishesAction> Client;

// 当action完成后会调用该回调函数一次
void doneCb(const actionlib::SimpleClientGoalState& state,
        const learning_communication::DoDishesResultConstPtr& result)
{
    ROS_INFO("Yay! The dishes are now clean");
    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::DoDishesFeedbackConstPtr& feedback)
{
    ROS_INFO(" percent_complete : %f ", feedback->percent_complete);
}

int main(int argc, char** argv)
{
    ros::init(argc, argv, "do_dishes_client");

    // 定义一个客户端
    Client client("do_dishes", 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::DoDishesGoal goal;
    goal.dishwasher_id = 1;

    // 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;
}

2.3.5 编译代码

# CMakeLists.txt文件
# 1.设置需要编译的代码和生成的可执行文件
# 2.设置链接库；
# 3.设置依赖；
add_executable(DoDishes_client src/DoDishes_client.cpp)
target_link_libraries(DoDishes_client ${catkin_LIBRARIES})
add_dependencies(DoDishes_client ${${PROJECT_NAME}_EXPORTED_TARGETS})

add_executable(DoDishes_server src/DoDishes_server.cpp)
target_link_libraries(DoDishes_server ${catkin_LIBRARIES})
add_dependencies(DoDishes_server ${${PROJECT_NAME}_EXPORTED_TARGETS})

# 4.编译工作空间；
cd ~/willard_ws/
catkin_make

# 5.运行
roscore
rosrun learning_communication DoDishes_client
rosrun learning_communication DoDishes_server

# CMakeLists.txt文件内容

cmake_minimum_required(VERSION 2.8.3)
project(learning_communication)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages

# =============================================
# 新增message_generation
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
  # ==action新增依赖==
  actionlib_msgs
  actionlib
  # ==================
)
# =============================================

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder

# =============================================
# 新增内容的位置
add_message_files(
    FILES
    Person.msg
#   Message1.msg
#   Message2.msg
)
# =============================================

## Generate services in the 'srv' folder

# =============================================
# 新增内容的位置
add_service_files(
    FILES
    Add.srv
#   Service1.srv
#   Service2.srv
)
# =============================================

## Generate actions in the 'action' folder

# =======================================================
# action新增内容的位置
add_action_files(
    FILES
    DoDishes.action
#   Action1.action
#   Action2.action
)
# =======================================================

## Generate added messages and services with any dependencies listed here

# =============================================
# 新增内容的位置
generate_messages(
    DEPENDENCIES
    std_msgs
    actionlib_msgs
)
# =============================================


################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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

# =============================================
# 需要新增内容的位置
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES learning_communication
   CATKIN_DEPENDS roscpp rospy std_msgs message_runtime
#  DEPENDS system_lib
)
# =============================================

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_communication.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_communication_node.cpp)

# 新增加的链接库和依赖
add_executable(talker src/talker.cpp)
target_link_libraries(talker ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)
add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
# add_dependencies(talker ${PROJECT_NAME}_generate_messages_cpp)

# ==================================================
# 服务新增加的依赖
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)
# ==================================================

# ======================================================================
# action新增加的依赖
add_executable(DoDishes_client src/DoDishes_client.cpp)
target_link_libraries(DoDishes_client ${catkin_LIBRARIES})
add_dependencies(DoDishes_client ${${PROJECT_NAME}_EXPORTED_TARGETS})

add_executable(DoDishes_server src/DoDishes_server.cpp)
target_link_libraries(DoDishes_server ${catkin_LIBRARIES})
add_dependencies(DoDishes_server ${${PROJECT_NAME}_EXPORTED_TARGETS})
# ======================================================================

## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_communication.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

3.分布式通信

# 实现分布式多机通信
# 1.远程登录设置
sudo apt-get install openssh-server		# 安装ssh服务
systemctl start ssh		# 开启ssh服务
sudo ps -e | grep ssh	# 查看ssh是否开启
ping IP地址			  # 测试网络连通性 	
sudo ssh 用户名@IP地址		# 远程登录
ifconfig				# 查看ip地址

# 2.设置IP地址
# 在本地端和远程端分别设置对方的IP地址

# 本地端
sudo vim /etc/hosts
===========================================================
127.0.0.1	localhost
127.0.1.1	ros

# 增加对方的IP地址和名字
192.168.66.103 ubuntu

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
===========================================================

# 远程端
===========================================================
127.0.0.1	localhost
127.0.1.1	ubuntu

# 增加对方的IP地址和名字
192.168.66.102 ros

# The following lines are desirable for IPv6 capable hosts
::1     ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
===========================================================

# 测试网络连通性
# 本地端
ping ubuntu

# 远程端
ping ros

# 3.从机端设置ROS_MASTER_URI
# 此处从机为hawkbot端的PC
sudo vim ~/.bashrc

==============================================
# 在~/.bashrc文件中添加内容
export ROBOT_IP=192.168.66.102	# 主机IP
export ROS_MASTER_URI=http://$ROBOT_IP:11311
==============================================

# 4.测试实例
# 4.1 启动master(主机：ros)
roscore

# 4.2 启动海龟(主机：ros)
rosrun turtlesim turtlesim_node

# 4.3 发布控制命令(从机：hawkbot)
rostopic pub -r 10 /turtle1/cmd_vel geometry_msgs/Twist "linear:
	x:2.0
	y:0.0
	z:0.0
angular:
	x:0.0
	y:0.0
	z:2.0
"

4.ROS的常用组件

4.1 Launch文件

${\rm Launch}$ 文件：通过 ${\rm XML}$ 文件实现多节点的配置和启动( ${\rm Launch}$ 可自动启动 ${\rm ROS\ Master}$ )；

# 1.<launch>标签
<launch>：launch文件的根元素采用<launch>标签定义；

# 2.<node>标签
<node>：启动节点
<node pkg="package-name" type="executable-name" name="node-name"/>
参数说明：
pkg：节点所在功能包名称；
type：节点可执行文件名称；
name：节点运行时的名称；
其他参数：output、respawn、required、ns、args；

# 3.<param>标签
<param>：设置ROS系统运行中的参数，存储在参数服务器中；
<param name="output_frame" value="odom"/>
参数说明：
name：参数名；
value：参数值；

# 4.<rosparam>标签
<rosparam>：加载参数文件中的多个参数；
<rosparam file="params.yaml" command="load" ns="params"/>

# 5.<arg>标签
<arg>：launch文件内部的局部变量，仅限于launch文件使用；
<arg name="arg-name" default="arg-value"/>
参数说明：
name：参数名；
value：参数值；
调用：
<param name="foo" value="$(arg arg-name)"/>
<node name="node" pkg="package" type="type" args="$(arg arg-name)"/>

# 6.<remap>标签
<remap>：重映射ROS计算图资源的命名；
<remap from="/turtlebot/cmd_vel"to="/cmd_vel"/>
参数说明：
from：原来的名字；
to：映射后的名字；

# 7.<include>标签
<include>：包含其他launch文件；
<include file="$(dirname)/other.launch"/>
参数说明：
file：包含的其他launch文件路径；

<!-- launch文件实例，gmapping_slam.launch实例 -->

<launch>
    <node pkg="gmapping" type="slam_gmapping" name="slam_gmapping" output="screen">
        <param name="transform_publish_period" value="0.1"/>
        <param name="base_frame" value="/base_footprint"/>
        <param name="odom_frame" value="/odom"/>
        <param name="map_frame" value="/map"/>
        <param name="map_update_interval" value="2.0"/>
        <param name="maxUrange" value="8"/>
        <param name="sigma" value="0.05"/>
        <param name="kernelSize" value="1"/>
        <param name="lstep" value="0.05"/>
        <param name="astep" value="0.05"/>
        <param name="iterations" value="5"/>
        <param name="lsigma" value="0.075"/>
        <param name="ogain" value="3.0"/>
        <param name="lskip" value="0"/>
        <param name="minimumScore" value="50"/>
        <param name="srr" value="0.1"/>
        <param name="srt" value="0.2"/>
        <param name="str" value="0.1"/>
        <param name="stt" value="0.2"/>
        <param name="linearUpdate" value="1.0"/>
        <param name="angularUpdate" value="0.2"/>
        <param name="temporalUpdate" value="0.5"/>
        <param name="resampleThreshold" value="0.5"/>
        <param name="particles" value="100"/>
        <param name="xmin" value="-10.0"/>
        <param name="ymin" value="-10.0"/>
        <param name="xmax" value="10.0"/>
        <param name="ymax" value="10.0"/>
        <param name="delta" value="0.03"/>
        <param name="llsamplerange" value="0.01"/>
        <param name="llsamplestep" value="0.01"/>
        <param name="lasamplerange" value="0.005"/>
        <param name="lasamplestep" value="0.005"/>
    </node>

    <node pkg="rviz" type="rviz" name="rviz1" required="true" args="-d $(find hawkbot)/rviz/slam.rviz"/>
</launch>

4.2 TF坐标变换

4.2.1 TF坐标变换例程

sudo apt-get install ros-melodic-turtle-tf	# 注意ros版本
roslaunch turtle_tf turtle_tf_demo.launch
rosrun turtlesim turtle_teleop_key
rosrun tf view_frames		# 生成tf关系图
rosrun tf tf_echo turtle1 turtle2	# 查看具体tf关系

海龟例程坐标变换公式：
${\rm T}_{turtle1\_turtle2}={\rm T}_{turtle1\_world}*{\rm T}_{world\_turtle2}$

4.2.2 TF广播器和TF监听器编程实现

${\rm TF}$ 坐标变换实现步骤

# 1.建立learning_tf功能包
cd ~/willard_ws/src/
catkin_create_pkg learning_tf std_msgs rospy roscpp

# 2.编译功能包
cd ~/willard_ws
catkin_make
source ~/willard_ws/devel/setup.bash

# 3.创建tf广播器.cpp
touch turtle_tf_broadcaster.cpp

# 4.创建tf监听器.cpp
touch turtle_tf_listener.cpp

# 5.编译代码(CMakeLists.txt)
# 设置需要编译的代码和生成的可执行文件；
# 设置链接库；
# ==================================================================
add_executable(turtle_tf_broadcaster src/turtle_tf_broadcaster.cpp)
target_link_libraries(turtle_tf_broadcaster ${catkin_LIBRARIES})

add_executable(turtle_tf_listener src/turtle_tf_listener.cpp)
target_link_libraries(turtle_tf_listener ${catkin_LIBRARIES})
# ==================================================================
# ======================================
# 其他需要修改
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
  tf
)
# ======================================

# 编译代码
cd ~/willard_ws/
catkin_make
soure devel/setup.bash

# 6.建立.launch文件，放置learning_tf/launch/下
# 启动.launch文件
roslaunch learning_tf start_demo_with_listener.launch

${\rm TF}$ 广播器编程实现
- 定义 ${\rm TF}$ 广播器 $({\rm TransformBroadcaster})$ ；
- 创建坐标变换值；
- 发布坐标变换 $({\rm sendTransform})$ ；
- 编程实现：
```
// turtle_tf_broadcaster.cpp文件
#include <ros/ros.h>
#include <tf/transform_broadcaster.h>
#include <turtlesim/Pose.h>

std::string turtle_name;

void poseCallback(const turtlesim::PoseConstPtr& msg)
{
    // tf广播器
    static tf::TransformBroadcaster br;

    // 根据乌龟当前的位姿，设置相对于世界坐标系的坐标变换
    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);

    // 发布坐标变换
    br.sendTransform(tf::StampedTransform(transform, ros::Time::now(), "world", turtle_name));
}

int main(int argc, char** argv)
{
    // 初始化节点
    ros::init(argc, argv, "my_tf_broadcaster");
    if (argc != 2)
    {
        ROS_ERROR("need turtle name as argument"); 
        return -1;
    };
    turtle_name = argv[1];

    // 订阅乌龟的pose信息
    ros::NodeHandle node;
    ros::Subscriber sub = node.subscribe(turtle_name+"/pose", 10, &poseCallback);

    ros::spin();

    return 0;
};
```
${\rm TF}$ 监听器编程实现
- 定义 ${\rm TF}$ 监听器 $({\rm TransformListener})$ ;
- 查找坐标变换 $({\rm waitForTransform、lookupTransform})$ ；
- 编程实现：
```
// turtle_tf_listener.cpp文件
#include <ros/ros.h>
#include <tf/transform_listener.h>
#include <geometry_msgs/Twist.h>
#include <turtlesim/Spawn.h>

int main(int argc, char** argv)
{
    // 初始化节点
    ros::init(argc, argv, "my_tf_listener");

    ros::NodeHandle node;

    // 通过服务调用，产生第二只乌龟turtle2
    ros::service::waitForService("spawn");
    ros::ServiceClient add_turtle =
    node.serviceClient<turtlesim::Spawn>("spawn");
    turtlesim::Spawn srv;
    add_turtle.call(srv);

    // 定义turtle2的速度控制发布器
    ros::Publisher turtle_vel =
    node.advertise<geometry_msgs::Twist>("turtle2/cmd_vel", 10);

    // tf监听器
    tf::TransformListener listener;

    ros::Rate rate(10.0);
    while (node.ok())
    {
        tf::StampedTransform transform;
        try
        {
            // 查找turtle2与turtle1的坐标变换
            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和turtle2之间的坐标变换，计算turtle2需要运动的线速度和角速度
        // 并发布速度控制指令，使turtle2向turtle1移动
        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;
};
```

编译文件 $({\rm CMakeLists.txt})$ ；

cmake_minimum_required(VERSION 2.8.3)
project(learning_tf)

## Compile as C++11, supported in ROS Kinetic and newer
# add_compile_options(-std=c++11)

## Find catkin macros and libraries
## if COMPONENTS list like find_package(catkin REQUIRED COMPONENTS xyz)
## is used, also find other catkin packages

# ===============================================
# tf修改部分
find_package(catkin REQUIRED COMPONENTS
  roscpp
  rospy
  std_msgs
  message_generation
  tf
)
# ===============================================

## System dependencies are found with CMake's conventions
# find_package(Boost REQUIRED COMPONENTS system)


## Uncomment this if the package has a setup.py. This macro ensures
## modules and global scripts declared therein get installed
## See http://ros.org/doc/api/catkin/html/user_guide/setup_dot_py.html
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
################################################

## To declare and build messages, services or actions from within this
## package, follow these steps:
## * Let MSG_DEP_SET be the set of packages whose message types you use in
##   your messages/services/actions (e.g. std_msgs, actionlib_msgs, ...).
## * In the file package.xml:
##   * add a build_depend tag for "message_generation"
##   * add a build_depend and a exec_depend tag for each package in MSG_DEP_SET
##   * If MSG_DEP_SET isn't empty the following dependency has been pulled in
##     but can be declared for certainty nonetheless:
##     * add a exec_depend tag for "message_runtime"
## * In this file (CMakeLists.txt):
##   * add "message_generation" and every package in MSG_DEP_SET to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * add "message_runtime" and every package in MSG_DEP_SET to
##     catkin_package(CATKIN_DEPENDS ...)
##   * uncomment the add_*_files sections below as needed
##     and list every .msg/.srv/.action file to be processed
##   * uncomment the generate_messages entry below
##   * add every package in MSG_DEP_SET to generate_messages(DEPENDENCIES ...)

## Generate messages in the 'msg' folder
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )

## Generate services in the 'srv' folder
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )

## Generate actions in the 'action' folder
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here
# generate_messages(
#   DEPENDENCIES
#   std_msgs
# )

################################################
## Declare ROS dynamic reconfigure parameters ##
################################################

## To declare and build dynamic reconfigure parameters within this
## package, follow these steps:
## * In the file package.xml:
##   * add a build_depend and a exec_depend tag for "dynamic_reconfigure"
## * In this file (CMakeLists.txt):
##   * add "dynamic_reconfigure" to
##     find_package(catkin REQUIRED COMPONENTS ...)
##   * uncomment the "generate_dynamic_reconfigure_options" section below
##     and list every .cfg file to be processed

## Generate dynamic reconfigure parameters in the 'cfg' folder
# generate_dynamic_reconfigure_options(
#   cfg/DynReconf1.cfg
#   cfg/DynReconf2.cfg
# )

###################################
## 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_tf
#  CATKIN_DEPENDS roscpp rospy std_msgs
#  DEPENDS system_lib
)

###########
## Build ##
###########

## Specify additional locations of header files
## Your package locations should be listed before other locations
include_directories(
# include
  ${catkin_INCLUDE_DIRS}
)

## Declare a C++ library
# add_library(${PROJECT_NAME}
#   src/${PROJECT_NAME}/learning_tf.cpp
# )

## Add cmake target dependencies of the library
## as an example, code may need to be generated before libraries
## either from message generation or dynamic reconfigure
# add_dependencies(${PROJECT_NAME} ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Declare a C++ executable
## With catkin_make all packages are built within a single CMake context
## The recommended prefix ensures that target names across packages don't collide
# add_executable(${PROJECT_NAME}_node src/learning_tf_node.cpp)

## Rename C++ executable without prefix
## The above recommended prefix causes long target names, the following renames the
## target back to the shorter version for ease of user use
## e.g. "rosrun someones_pkg node" instead of "rosrun someones_pkg someones_pkg_node"
# set_target_properties(${PROJECT_NAME}_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
# add_dependencies(${PROJECT_NAME}_node ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})

## Specify libraries to link a library or executable target against
# target_link_libraries(${PROJECT_NAME}_node
#   ${catkin_LIBRARIES}
# )

# ======================================================================
# tf新增内容
add_executable(turtle_tf_broadcaster src/turtle_tf_broadcaster.cpp)
target_link_libraries(turtle_tf_broadcaster ${catkin_LIBRARIES})

add_executable(turtle_tf_listener src/turtle_tf_listener.cpp)
target_link_libraries(turtle_tf_listener ${catkin_LIBRARIES})
# ======================================================================

#############
## Install ##
#############

# all install targets should use catkin DESTINATION variables
# See http://ros.org/doc/api/catkin/html/adv_user_guide/variables.html

## Mark executable scripts (Python etc.) for installation
## in contrast to setup.py, you can choose the destination
# install(PROGRAMS
#   scripts/my_python_script
#   DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark executables for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_executables.html
# install(TARGETS ${PROJECT_NAME}_node
#   RUNTIME DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
# )

## Mark libraries for installation
## See http://docs.ros.org/melodic/api/catkin/html/howto/format1/building_libraries.html
# install(TARGETS ${PROJECT_NAME}
#   ARCHIVE DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   LIBRARY DESTINATION ${CATKIN_PACKAGE_LIB_DESTINATION}
#   RUNTIME DESTINATION ${CATKIN_GLOBAL_BIN_DESTINATION}
# )

## Mark cpp header files for installation
# install(DIRECTORY include/${PROJECT_NAME}/
#   DESTINATION ${CATKIN_PACKAGE_INCLUDE_DESTINATION}
#   FILES_MATCHING PATTERN "*.h"
#   PATTERN ".svn" EXCLUDE
# )

## Mark other files for installation (e.g. launch and bag files, etc.)
# install(FILES
#   # myfile1
#   # myfile2
#   DESTINATION ${CATKIN_PACKAGE_SHARE_DESTINATION}
# )

#############
## Testing ##
#############

## Add gtest based cpp test target and link libraries
# catkin_add_gtest(${PROJECT_NAME}-test test/test_learning_tf.cpp)
# if(TARGET ${PROJECT_NAME}-test)
#   target_link_libraries(${PROJECT_NAME}-test ${PROJECT_NAME})
# endif()

## Add folders to be run by python nosetests
# catkin_add_nosetests(test)

${\rm Launch}$ 文件启动

<!-- start_demo_with_listener.launch文件 -->
<launch>
    <!-- 海龟仿真器 -->
    <node pkg="turtlesim" type="turtlesim_node" name="sim"/>

    <!-- 键盘控制 -->
    <node pkg="turtlesim" type="turtle_teleop_key" name="teleop" output="screen"/>

    <!-- 两只海龟的tf广播 -->
    <node pkg="learning_tf" type="turtle_tf_broadcaster"
          args="/turtle1" name="turtle1_tf_broadcaster" />
    <node pkg="learning_tf" type="turtle_tf_broadcaster"
          args="/turtle2" name="turtle2_tf_broadcaster" />

    <!-- 监听tf广播，并且控制turtle2移动 -->
    <node pkg="learning_tf" type="turtle_tf_listener"
          name="listener" />

 </launch>

4.3 Rviz可视化平台简介

${\rm rviz}$ 中，可以使用可扩展标记语言 ${\rm XML}$ 对机器人、周围物体等任何实物进行尺寸、质量、位置、材质、关节等属性的描述，且在界面中呈现出来；
${\rm rviz}$ 可以通过图形化的方式，实时显示机器人传感器的信息、机器人的运动状态、周围环境的变化等信息；
${\rm rviz}$ 可通过机器人模型参数、机器人发布的传感信息等数据，为用户进行所有可监测信息的图形化显示；用户和开发者可以在 ${\rm rviz}$ 控制界面下，通过按钮、滑动条、数值等方式，控制机器人的行为；
${\rm rviz}$ 界面介绍：

4.4 Gazebo物理仿真环境简介

${\rm Gazebo}$ 简介
- ${\rm Gazebo}$ 是一款功能强大的三维物理仿真平台；
- 具备强大的物理引擎；
- 高质量的图形渲染；
- 方便的编程与图形接口；
- 开源免费；
${\rm Gazebo}$ 典型应用场景
- 测试机器人算法；
- 机器人的设计；
- 现实情境下的回溯测试；
${\rm Gazebo}$ 主要插件
- ${\rm gazebo\_ros}$ ：主要用于 ${\rm gazebo}$ 接口和封装、 ${\rm gazebo}$ 服务端和客户端的启动、 ${\rm URDF}$ 模型生成等；
- ${\rm gazebo\_msgs}$ ： ${\rm gazebo}$ 的 ${\rm Msg}$ 和 ${\rm Srv}$ 数据结构；
- ${\rm gazebo\_plugins}$ ：用于 ${\rm gazebo}$ 的通用传感器插件；
- ${\rm gazebo\_ros\_api\_plugin}、{\rm gazebo\_ros\_path\_plugin}$ ：实现接口封装；
使用 ${\rm Gazebo}$ 仿真步骤
1. 创建仿真环境；
2. 配置机器人模型；
3. 开始仿真；