ros 開發要點（初級實作topic，service，message，launch）

ROS,機器人作業系統，花了一天時間實作了幾個小功能：topic的訂閱預釋出，service的建立與請求，message的使用，launch的建立一次啟動多個節點。下面是主要幾個需要注意的地方，實作文檔主要參考官方wiki：http://wiki.ros.org/cn/ROS/Tutorials 。 

1, 環境

new ros workspace must execute "souce devel/setup.sh" to add $ROS_PACKAGE_PATH 

eg : /home/osboxes/catkin_ws/src:/opt/ros/kinetic/share

or ros filesystem level cannot find package in this new workspace !

2, 編譯

compile package hello_world:

[email protected]:~/catkin_ws$ rosed hello_world CMakeLists.txt 

add (just for talker node):

include_directories(include ${catkin_INCLUDE_DIRS})

add_executable(talker src/talker.cpp)

target_link_libraries(talker ${catkin_LIBRARIES})

add_dependencies(talker hello_world_generate_messages_cpp)

3,建立一個launch

creat a launch !!!

osboxe[email protected]:~/catkin_ws$ roslaunch hello_world hellolaunch.launch

<launch>

    <node pkg="hello_world" type="talker" name="talker">

    </node>

    <node pkg="hello_world" type="listener" name="listener">

    </node>

</launch>

4,在節點中建立一個service

creat a service in a node !!!

[email protected]:~/catkin_ws$ rossrv package hello_world 

hello_world/hello_srv

[email protected]:~/catkin_ws$ rossrv show hello_world/hello_srv 

int32 A

int32 B

int32 C

---

int32 sum

//code start

bool add(hello_world::hello_srv::Request &req,hello_world::hello_srv::Response &res)

{

  res.sum = req.A +req.B + req.C ;

  ROS_INFO("sending back response:[%ld]",(int)res.sum);

  return true ;

}

ros::ServiceServer service = n.advertiseService("add_3_ints",add);

code end

[email protected]:~/catkin_ws$ rosservice list

/add_3_ints

[email protected]:~/catkin_ws$ rosservice type /add_3_ints 

hello_world/hello_srv

[email protected]:~/catkin_ws$ rosservice call /add_3_ints 1 1 1

sum: 3

5.在建立一個message

create a msg in a node !!!

[email protected]:~/catkin_ws$ rosmsg show hello_world/hello 

int32 A

int32 B

int32 C

code start talker.cpp

ros::Publisher chatter_pub = n.advertise<hello_world::hello>("chatter", 1000);

code end

code start  lisener.cpp

void chatterCallback(const hello_world::hello::ConstPtr& msg)

{

  ROS_INFO("I heard: [%d] [%d] [%d]", msg->A, msg->B, msg->C);

}

ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);

code end

6，節點中建立一個話題和訂閱這個話題

///code start

ros::Publisher chatter_pub = n.advertise<hello_world::hello>("chatter", 1000);

ros::Subscriber sub = n.subscribe("chatter", 1000, chatterCallback);

///code end

7，調試

rosrun rqt_graph rqt_graph 

rosrun rqt_console rqt_console