ROS節點通訊（三）action
阿新 • • 發佈：2021-07-10
官方wiki：http://wiki.ros.org/actionlib
目錄1、說明
ROS中的action也是節點通訊的一種方式，其和service-client的不同點在於，service-client是一問一答模式，而action則多了一個反饋機制，即服務端不間斷給客戶端反饋
api參考：https://docs.ros.org/en/api/actionlib/html/classactionlib_1_1SimpleActionClient.html
2、程式碼示例
跳過建立工作區和功能包步驟
2.1、定義資料結構
action定義的資料結構分成三個部分，中間用 --- 隔開，按照順序如下：
2.1.1、goal
為了使action完成任務，引入一個目標概念，由客戶端傳送到服務端
2.1.4、result
結果由服務端傳送給客戶端，在完成 goal 之後，傳送的任務結果
2.1.3、feedback
反饋為服務端傳送到客戶端，高度客戶端，當前任務的進展
TestData.action
#請求的資料，一般由客戶端傳送給服務端 uint32 id --- #請求結果，一般由服務端傳送給客戶端 uint32 total --- #反饋的訊息內容，一般由服務端不間斷髮送到客戶端 float32 percent
.action 檔案預設儲存在 action 目錄下
對於該檔案，會生成7個訊息型別，以便客戶端和服務端通訊，這些型別由 genaction.py 生成：
- TestDataAction.msg
- TestDataActionGoal.msg
- TestDataActionResult.msg
- TestDataActionFeedback.msg
- TestDataGoal.msg
- TestDataResult.msg
- TestDataFeedback.msg
2.2、服務端
#include <ros/ros.h> #include <test_action/TestDataAction.h> #include <actionlib/server/simple_action_server.h> typedef actionlib::SimpleActionServer<test_action::TestDataAction> Server; void execute(const test_action::TestDataGoalConstPtr& goal, Server* server) { ros::Rate rate(1); test_action::TestDataFeedback feedback; ROS_INFO("Dishwasher %d is working.", goal->id); for(int index = 1; index <= 10; index++) { feedback.percent = index * 10; server->publishFeedback(feedback); rate.sleep(); } ROS_INFO("Dishwasher %d finish working.", goal->id); server->setSucceeded(); } int main(int argc, char** argv) { ros::init(argc, argv, "test_action_service"); ros::NodeHandle handle; //構建一個action服務，第二個引數是服務的名稱，客戶端需要根據這個唯一的名稱進行連線 //最後一個引數表示是否構建完成之後就開始執行，一般應該設定為false，並在構建完成之後使用start()方法開始 Server server(handle, "do_action", boost::bind(&execute, _1, &server), false); server.start(); ros::spin(); return 0; }
2.3、客戶端
#include <ros/ros.h>
#include <test_action/TestDataAction.h>
#include <actionlib/client/simple_action_client.h>
typedef actionlib::SimpleActionClient<test_action::TestDataAction> Client;
//完成呼叫回撥
void doneCb(const actionlib::SimpleClientGoalState& state,
const test_action::TestDataResultConstPtr& result)
{
ROS_INFO("The dishes are now clean");
ros::shutdown();
}
void activeCb()
{
ROS_INFO("goal just went active");
}
//反饋
void feedbackCb(const test_action::TestDataFeedbackConstPtr& feedback)
{
ROS_INFO("percent: %f", feedback->percent);
}
int main(int args, char** argv)
{
ros::init(args, argv, "test_action_client");
Client client("do_action", true);
ROS_INFO("waiting for action server to start");
client.waitForServer();
ROS_INFO("action server started, sending goal");
test_action::TestDataGoal goal;
goal.id = 9;//填入goal
//客戶端傳送目標，後三個是各個階段的回撥，分別在完成時、通訊剛啟用時和反饋過程中
client.sendGoal(goal, &doneCb, &activeCb, &feedbackCb);
ros::spin();
return 0;
}
2.4、構建配置
CMakeLists.txt需要新增以下包依賴
find_package(catkin REQUIRED genmsg actionlib_msgs actionlib)
add_action_files(DIRECTORY action FILES DoDishes.action)
generate_messages(DEPENDENCIES actionlib_msgs)
其中，genmsg 和 actionlib_msgs 是構建 .action 檔案的時候需要的依賴，actionlib 是編譯的時候需要的依賴
packages.xml 配置
<buildtool_depend>catkin</buildtool_depend>
<buildtool_depend>genmsg</buildtool_depend>
<build_export_depend>actionlib_msgs</build_export_depend>
<build_depend>actionlib</build_depend>
<build_depend>actionlib_msgs</build_depend>
<exec_depend>actionlib</exec_depend>
<exec_depend>actionlib_msgs</exec_depend>
2.5、結果
服務端：
[ INFO] [1621921903.942496821]: Dishwasher 9 is working.
[ INFO] [1621921913.942535907]: Dishwasher 9 finish working.
客戶端：
[ INFO] [1621921903.728245862]: waiting for action server to start
[ INFO] [1621921903.941538934]: action server started, sending goal
[ INFO] [1621921903.942692392]: goal just went active
[ INFO] [1621921903.943088999]: percent: 10.000000
[ INFO] [1621921904.942911217]: percent: 20.000000
[ INFO] [1621921905.942921653]: percent: 30.000000
[ INFO] [1621921906.942895095]: percent: 40.000000
[ INFO] [1621921907.942843906]: percent: 50.000000
[ INFO] [1621921908.942901935]: percent: 60.000000
[ INFO] [1621921909.942896131]: percent: 70.000000
[ INFO] [1621921910.942844776]: percent: 80.000000
[ INFO] [1621921911.942889215]: percent: 90.000000
[ INFO] [1621921912.942941318]: percent: 100.000000
[ INFO] [1621921913.943146759]: The dishes are now clean