编写简单的发布器和订阅器并测试

使用c++和python两种方式

---

首先使用c++

1：创建一个发布器节点

mkdir -p ~/catkin_ws/src/beginner_tutorials/src 先创建一个文件夹，用于存储该代码包的源码

具体代码参考tutorial

1. 初始化 ROS 系统
2. 在 ROS 网络内广播我们将要在 chatter 话题上发布 std_msgs/String 类型的消息
3. 以每秒 10 次的频率在 chatter 上发布消息

2：创建一个接收节点

1. 初始化ROS系统
2. 订阅 chatter 话题
3. 进入自循环，等待消息的到达
4. 当消息到达，调用 chatterCallback() 函数

3：编译

在beginner_tutorials中的cmakelist.txt中添加如下。保持原来上一个例子的改动。添加的msg和srv

include_directories(include ${catkin_INCLUDE_DIRS})

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

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

对可执行文件添加对消息文件的依赖，举例如下，对talker添加依赖

add_dependencies(talker beginner_tutorials_generate_messages_cpp)

这样就可以确保自定义消息的头文件在被使用之前已经被生成。因为 catkin 把所有的 package 并行的编译，所以如果你要使用其他 catkin 工作空间中其他 package 的消息，你同样也需要添加对他们各自生成的消息文件的依赖

 

然后可执行catkin_make, 对应的打印信息如下，可见对应的talker和listener的生成。

root@ben-virtual-machine:~/catkin_ws# catkin_make
Base path: /root/catkin_ws
Source space: /root/catkin_ws/src
Build space: /root/catkin_ws/build
Devel space: /root/catkin_ws/devel
Install space: /root/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/root/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /root/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /root/catkin_ws/devel;/opt/ros/kinetic
-- This workspace overlays: /root/catkin_ws/devel;/opt/ros/kinetic
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /root/catkin_ws/build/test_results
-- Found gmock sources under '/usr/src/gmock': gmock will be built
-- Found gtest sources under '/usr/src/gmock': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.7.14
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing 1 packages in topological order:
-- ~~  - beginner_tutorials
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'beginner_tutorials'
-- ==> add_subdirectory(beginner_tutorials)
-- Using these message generators: gencpp;geneus;genlisp;gennodejs;genpy
-- beginner_tutorials: 1 messages, 1 services
-- Configuring done
-- Generating done
-- Build files have been written to: /root/catkin_ws/build
####
#### Running command: "make -j2 -l2" in "/root/catkin_ws/build"
####
[  0%] Built target std_msgs_generate_messages_cpp
[  0%] Built target _beginner_tutorials_generate_messages_check_deps_Num
[  0%] Built target _beginner_tutorials_generate_messages_check_deps_AddTwoInts
[  0%] Built target std_msgs_generate_messages_eus
[  0%] Built target std_msgs_generate_messages_lisp
[  0%] Built target std_msgs_generate_messages_py
[  0%] Built target std_msgs_generate_messages_nodejs
[ 11%] Built target beginner_tutorials_generate_messages_cpp
[ 29%] Built target beginner_tutorials_generate_messages_eus
[ 41%] Built target beginner_tutorials_generate_messages_lisp
[ 64%] Built target beginner_tutorials_generate_messages_py
[ 76%] Built target beginner_tutorials_generate_messages_nodejs
Scanning dependencies of target listener
Scanning dependencies of target talker
[ 88%] Building CXX object beginner_tutorials/CMakeFiles/listener.dir/src/listener.cpp.o
[ 88%] Building CXX object beginner_tutorials/CMakeFiles/talker.dir/src/talker.cpp.o
[ 94%] Linking CXX executable /root/catkin_ws/devel/lib/beginner_tutorials/talker
[100%] Linking CXX executable /root/catkin_ws/devel/lib/beginner_tutorials/listener
[100%] Built target talker
[100%] Built target listener
[100%] Built target beginner_tutorials_generate_messages

 

测试结果，如果新打开终端，需要执行下面语句，否则找不到packet

cd ~/catkin_ws
source ./devel/setup.bash

启动一个发布器，

rosrun beginner_tutorials talker 

启动一个订阅器

rosrun beginner_tutorials listener

结果如下，右边是发布器，左边是订阅器

 

python 版本

首先创建目录
$ mkdir scripts
$ cd scripts

将这一行打开，支持python

然后编译，发现下面的错误，没有找到setup.py文件，记录下面的log

root@ben-virtual-machine:~/catkin_ws# catkin_make
Base path: /root/catkin_ws
Source space: /root/catkin_ws/src
Build space: /root/catkin_ws/build
Devel space: /root/catkin_ws/devel
Install space: /root/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/root/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /root/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /root/catkin_ws/devel;/opt/ros/kinetic
-- This workspace overlays: /root/catkin_ws/devel;/opt/ros/kinetic
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /root/catkin_ws/build/test_results
-- Found gmock sources under '/usr/src/gmock': gmock will be built
-- Found gtest sources under '/usr/src/gmock': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.7.14
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing 1 packages in topological order:
-- ~~  - beginner_tutorials
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'beginner_tutorials'
-- ==> add_subdirectory(beginner_tutorials)
-- Using these message generators: gencpp;geneus;genlisp;gennodejs;genpy
CMake Error at /opt/ros/kinetic/share/catkin/cmake/catkin_python_setup.cmake:31 (message):
  catkin_python_setup() called without 'setup.py' in project folder '
  /root/catkin_ws/src/beginner_tutorials'
Call Stack (most recent call first):
  beginner_tutorials/CMakeLists.txt:24 (catkin_python_setup)

-- Configuring incomplete, errors occurred!
See also "/root/catkin_ws/build/CMakeFiles/CMakeOutput.log".
See also "/root/catkin_ws/build/CMakeFiles/CMakeError.log".
Makefile:738: recipe for target 'cmake_check_build_system' failed
make: *** [cmake_check_build_system] Error 1
Invoking "make cmake_check_build_system" failed

在beginner tutorials的软件包的根目录创建setup.py文件，文件内容如下

from distutils.core import setup
 
setup(
    version='0.0.0',
    scripts=['scripts/talker.py','scripts/listener.py'],
    packages=['beginner_tutorials'],
    package_dir={'': 'scripts'}
)

再次执行编译, 注意，复制的setup.py格式有可能不对，最好自己输入，下面是记录的结果

root@ben-virtual-machine:~/catkin_ws# catkin_make
Base path: /root/catkin_ws
Source space: /root/catkin_ws/src
Build space: /root/catkin_ws/build
Devel space: /root/catkin_ws/devel
Install space: /root/catkin_ws/install
####
#### Running command: "make cmake_check_build_system" in "/root/catkin_ws/build"
####
-- Using CATKIN_DEVEL_PREFIX: /root/catkin_ws/devel
-- Using CMAKE_PREFIX_PATH: /root/catkin_ws/devel;/opt/ros/kinetic
-- This workspace overlays: /root/catkin_ws/devel;/opt/ros/kinetic
-- Using PYTHON_EXECUTABLE: /usr/bin/python
-- Using Debian Python package layout
-- Using empy: /usr/bin/empy
-- Using CATKIN_ENABLE_TESTING: ON
-- Call enable_testing()
-- Using CATKIN_TEST_RESULTS_DIR: /root/catkin_ws/build/test_results
-- Found gmock sources under '/usr/src/gmock': gmock will be built
-- Found gtest sources under '/usr/src/gmock': gtests will be built
-- Using Python nosetests: /usr/bin/nosetests-2.7
-- catkin 0.7.14
-- BUILD_SHARED_LIBS is on
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- ~~  traversing 1 packages in topological order:
-- ~~  - beginner_tutorials
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-- +++ processing catkin package: 'beginner_tutorials'
-- ==> add_subdirectory(beginner_tutorials)
-- Using these message generators: gencpp;geneus;genlisp;gennodejs;genpy
-- beginner_tutorials: 1 messages, 1 services
-- Configuring done
-- Generating done
-- Build files have been written to: /root/catkin_ws/build
####
#### Running command: "make -j2 -l2" in "/root/catkin_ws/build"
####
[  0%] Built target std_msgs_generate_messages_cpp
[  0%] Built target _beginner_tutorials_generate_messages_check_deps_Num
[  0%] Built target _beginner_tutorials_generate_messages_check_deps_AddTwoInts
[  0%] Built target std_msgs_generate_messages_eus
[  0%] Built target std_msgs_generate_messages_py
[  0%] Built target std_msgs_generate_messages_lisp
[  0%] Built target std_msgs_generate_messages_nodejs
[ 11%] Built target beginner_tutorials_generate_messages_cpp
[ 29%] Built target beginner_tutorials_generate_messages_eus
[ 52%] Built target beginner_tutorials_generate_messages_py
[ 64%] Built target beginner_tutorials_generate_messages_lisp
[ 76%] Built target listener
[ 88%] Built target beginner_tutorials_generate_messages_nodejs
[100%] Built target talker
[100%] Built target beginner_tutorials_generate_messages

测试，结果和c++一样，生成的两个文件在devel/bin下面

rosrun beginner_tutorials talker.py

rosrun beginner_tutorials listener.py