ROS文件系统

Posted 2022-04-12 loongembedded

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文章目录

参考链接
1.文件系统结构
2. 工作空间src目录

参考链接

(1) 机器人操作系统入门（二）ROS文件系统：添加链接描述

(2) 详解ROS文件系统：添加链接描述

1.文件系统结构

ROS文件系统指的是ROS源代码的组织形式，其结构大致如下图：

默认包含三个文件夹：

src/: ROS的catkin软件包（C++源代码包）
build/: catkin（CMake）的缓存信息和中间文件
devel/: 生成的目标文件（包括头文件，动态链接库，静态链接库，可执行文件等）、环境变量

在编译过程中，这三者关系如下

build和devel由catkin系统自动生成、管理，我们日常的开发一般不会去涉及，而主要用到的是src文件夹，我们写的ROS程序、网上下载的ROS源代码包都存放在这里。

在编译时，catkin编译系统会递归的查找和编译src/下的每一个源代码包

2. 工作空间src目录

2.1 CMakeLists.txt文件

在工作空间catkin_ws/src目录下执行catkin_init_workspace 初始化工作空间时，生成的CMakeLists.txt为功能包编译配置，此文件的详细解析见添加链接描述

2.2 功能包目录结构

|--- src: 源码

        |-- package：功能包(ROS基本单元)包含多个节点、库与配置文件，包名所有字母小写，只能由字母、数字与下划线组成
            |-- CMakeLists.txt 配置编译规则，比如源文件、依赖项、目标文件
            |-- package.xml 包信息，比如:包名、版本、作者、依赖项...(以前版本是 manifest.xml)
            |-- scripts 存储python文件
            |-- src 存储C++源文件
            |-- include 头文件
            |-- msg 消息通信格式文件
            |-- srv 服务通信格式文件
            |-- action 动作格式文件
            |-- launch 可一次性运行多个节点 
            |-- config 配置信息
        |-- CMakeLists.txt: 编译的基本配置

比如上图的helloworld功能包，比较简单，下面以helloworld功能包来描述一个包的结构

2.2.1 CMakeLists.txt文件

(1) CMakeLists.txt作用
CMakeLists.txt原本是Cmake编译系统的规则文件，而Catkin编译系统基本沿用了CMake的编译风格，只是针对ROS工程添加了一些宏定义。所以在写法上，catkin的CMakeLists.txt与CMake的基本一致。

这个文件直接规定了这个package要依赖哪些package，要编译生成哪些目标，如何编译等等流程。所以CMakeLists.txt非常重要，它指定了由源码到目标文件的规则，catkin编译系统在工作时首先会找到每个package下的CMakeLists.txt，然后按照规则来编译构建。

(2) CMakeLists.txt语法

cmake_minimum_required(VERSION 3.0.2)#所需cmake版本
project(helloworld) #包名称，会被 $PROJECT_NAME 的方式调用

## 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
#设置构建所需要的软件包
find_package(catkin REQUIRED COMPONENTS
  roscpp
 # rospy #我这里如果没有注释掉rospy，编译出错，目前还不知道具体原因，因为我用C++，暂时没用python，先这么处理。
  std_msgs
)

## System dependencies are found with CMake's conventions
#默认添加系统依赖
# 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
# 启动 python 模块支持
# catkin_python_setup()

################################################
## Declare ROS messages, services and actions ##
## 声明 ROS 消息、服务、动作... ##
################################################

## 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
#生成自定义msg文件
# add_message_files(
#   FILES
#   Message1.msg
#   Message2.msg
# )

## Generate services in the 'srv' folder
#生成自定义srv文件
# add_service_files(
#   FILES
#   Service1.srv
#   Service2.srv
# )

## Generate actions in the 'action' folder
#生成自定义action文件
# add_action_files(
#   FILES
#   Action1.action
#   Action2.action
# )

## Generate added messages and services with any dependencies listed here
# 生成消息、服务时的依赖包
# generate_messages(
#   DEPENDENCIES
#   std_msgs
# )

################################################
## Declare ROS dynamic reconfigure parameters ##
## 声明 ROS 动态参数配置 ##
################################################

## 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 ##
## catkin 特定配置##
###################################
## 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
#生成当前package的cmake配置，供依赖本包的其他软件包调用
catkin_package(
#  INCLUDE_DIRS include
#  LIBRARIES helloworld
#  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
# 指定头文件路径，当前功能包的头文件路径位于其他文件路径之前
include_directories(
# include
  $catkin_INCLUDE_DIRS
)

## Declare a C++ library
# 声明 C++ 库
# add_library($PROJECT_NAME
#   src/$PROJECT_NAME/helloworld.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
#添加库的cmake目标以来；定义目标文件依赖于的其他目标文件，确保其他目标已被构建
# 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
# 声明 C++ 可执行文件，这里是hw
 add_executable(hw src/helloworld.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"
#重命名c++可执行文件
# set_target_properties($PROJECT_NAME_node PROPERTIES OUTPUT_NAME node PREFIX "")

## Add cmake target dependencies of the executable
## same as for the library above
#添加可执行文件的 cmake 目标依赖
# add_dependencies($PROJECT_NAME_node $$PROJECT_NAME_EXPORTED_TARGETS $catkin_EXPORTED_TARGETS)

## Specify libraries to link a library or executable
 target against
 #指定库、可执行文件的链接库，这里是为可执行文件hw指定链接的库，$catkin_LIBRARIES 是ROS的基本库：catkin库。把生成的可执行文件和catkin库链接到一起。
 target_link_libraries(hw
   $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
#设置用于安装的可执行脚本
# catkin_install_python(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
# 安装目标文件到本地系统
# 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_helloworld.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 package.xml文件

package.xml也是一个catkin的package必备文件，它是这个软件包的描述文件
(1) package.xml作用
pacakge.xml包含了package的名称、版本号、内容描述、维护人员、软件许可、编译构建工具、编译依赖、运行依赖等信息。实际上rospack find、rosdep等命令之所以能快速定位和分析出package的依赖项信息，就是直接读取了每一个pacakge中的package.xml文件。它为用户提供了快速了解一个pacakge的渠道。

(2) package.xml语法
pacakge.xml遵循xml标签文本的写法，由于版本更迭原因，现在有两种格式并存（format1与format2），不过区别不大，我们现在用的是format2格式的。

<?xml version="1.0"?>
<!-- 格式: 以前是 1，推荐使用格式 2 -->
<package format="2">
<!-- 包名 -->
  <name>helloworld</name>
  <!-- 版本号 -->
  <version>0.0.0</version>
  <!-- 功能包的描述信息 -->
  <description>The helloworld package</description>

  <!-- One maintainer tag required, multiple allowed, one person per tag -->
  <!-- Example:  -->
   <!-- 维护人员信息，可以多个，每个人一个tag -->
  <!-- <maintainer email="jane.doe@example.com">Jane Doe</maintainer> -->
  <maintainer email="kandi@todo.todo">kandi</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 -->
  <!-- 许可证信息，ROS核心组件默认 BSD -->
  <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/helloworld</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: -->
  <!-- 测试用例依赖项 -->
  <!--   <test_depend>gtest</test_depend> -->
  <!-- Use doc_depend for packages you need only for building documentation: -->
  <!-- 文档依赖项 -->
  <!--   <doc_depend>doxygen</doc_depend> -->
  <!-- 依赖的编译构建工具，这是必须的，通常为catkin -->
  <buildtool_depend>catkin</buildtool_depend>
  <!-- 编译的依赖项，如roscpp功能包 -->
  <build_depend>roscpp</build_depend>
  <build_depend>rospy</build_depend>
  <build_depend>std_msgs</build_depend>
  <!-- 导出的依赖项 -->
  <build_export_depend>roscpp</build_export_depend>
  <build_export_depend>rospy</build_export_depend>
  <build_export_depend>std_msgs</build_export_depend>
  <!-- 运行时的依赖项 -->
  <exec_depend>roscpp</exec_depend>
  <exec_depend>rospy</exec_depend>
  <exec_depend>std_msgs</exec_depend>


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

  </export>
</package>

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