Writing ROS programs

Writing ROS programs

参考：

A Gentle Introduction to ROS

Jason M. O’Kane

Creating a workspace and a package

Creating a workspace:

$ mkdir workspaceName

Creating a package:

$ catkin_create_pkg agitr

A simple program

(1) Writing source file,

named hello.cpp, belongs in your package folder, right next to package.xml and CMake-Lists.txt.

(2) Compiling the Hello program.

Declaring dependencies. To list dependencies, edit the CMakeLists.txt in your package directory.

$ find_package(catkin REQUIRED COMPONENTS roscpp)

list dependencies in the package manifest (package.xml), using the build-

_depend and run_depend elements:

Steps:

$ source /opt/ros/hydro/setup.bash

$ mkdir -p ~/ros_workspace/src

$ cd src

~/ros_workspace/src$ catkin_create_pkg agitr

~/ros_workspace/src/ros_package$ mkdir src

当package中的.cpp文件很多时，建一个src放源代码文件会有帮助，.cpp文件不多时也可以建。

Declaring dependencies

In CMakeLists.txt:

Dependencies on other catkin packages can be added in a COMPONENTS section on this line:

find_package(catkin REQUIRED COMPONENTS package-names)

比如：

find_package(catkin REQUIRED COMPONENTS
cv_bridge
dynamic_reconfigure
image_transport
image_geometry
kobuki_msgs
nodelet
pcl_ros
roscpp
std_msgs
turtlebot_msgs
visualization_msgs
tf
pcl_conversions
)

In manifest.xml：

list dependencies in the package manifest (package.xml)

We should also list dependencies in the package manifest (package.xml), using the build_depend and run_depend elements:

<build_depend>package-name</build_depend>
<run_depend>package-name</run_depend>

In our example, the hello program needs roscpp both at build time and at run time, so the

manifest should contain:

<build_depend>roscpp</build_depend>
<run_depend>roscpp</run_depend>

Declaring an executable

In CMakeLists.txt:

add two lines to CMakeLists.txt declaring

the executable we would like to create. The general form is

add_executable(executable-name source-files)
target_link_libraries(executable-name ${catkin_LIBRARIES})

例子：

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

Building the workspace

Once your CMakeLists.txt is set up, you can build your workspace—including

compiling all of the executables in all of its packages—using this command:

In workspace directory:

catkin_make