ROS 파라미터

• 기존 서비스에 변수 입력값을 추가로 줄 수 있는 것을 ROS에서 파라미터(parameter)라고 함
• 이번 실습에서는 두개의 숫자를 계산하는 서비스 서버와 클라이언트를 만들고,
• 파라미터로 사칙연산 연산자를 정해주는 실습을 수행함

package.xml

CMakeLists.txt

//service_server_param

#include "ros/ros.h" // ROS Default Header File

#include "ros_param/SrvTutorial.h"// action Library Header File

#define PLUS 1 // Addition

#define MINUS 2 // Subtraction

#define MULTIPLICATION 3 // Multiplication

#define DIVISION 4 // Division

#define SQUARE 5

int g_operator = PLUS;

// The process below is performed if there is a service request

// The service request is declared as 'req', and the service response is declared as 'res'

bool calculation(ros_param::SrvTutorial::Request &req,

ros_param::SrvTutorial::Response &res)

{

// The operator will be selected according to the parameter value and calculate 'a' and 'b',

// which were received upon the service request.

// The result is stored as the Response value.

switch(g_operator)

{

case PLUS:

res.result = req.a + req.b; break;

case MINUS:

res.result = req.a - req.b; break;

case MULTIPLICATION:

res.result = req.a * req.b; break;

case DIVISION:

if(req.b == 0)

{

res.result = 0; break;

}

else

{

res.result = req.a / req.b; break;

}

case SQUARE:

res.result = req.a;

for (int i = 0; i < req.b - 1; i++)

{

res.result *= req.a;

}

break;

default:

res.result = req.a + req.b; break;

}

// Displays the values of 'a' and 'b' used in the service request, and the 'result' value

// corresponding to the service response.

ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (long int)req.b);

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

return true;

}

int main(int argc, char **argv) // Node Main Function

{

ros::init(argc, argv, "service_server_param"); // Initializes Node Name

ros::NodeHandle nh; // Node handle declaration

nh.setParam("calculation_method", PLUS); // Reset Parameter Settings

// Declare service server 'service_server_param' using the 'SrvTutorial' service file

// in the 'ros_param' package. The service name is 'ros_param_srv' and

// it is set to execute a 'calculation' function when a service is requested.

ros::ServiceServer ros_tutorials_service_server = nh.advertiseService("ros_param_srv", calculation);

ROS_INFO("ready srv server!");

ros::Rate r(10); // 10 hz

while (ros::ok())

{

nh.getParam("calculation_method", g_operator); // Select the operator according to the value received from the parameter.

ros::spinOnce(); // Callback function process routine

r.sleep(); // Sleep for routine iteration

}

return 0;

}

//service_client_param

#include "ros/ros.h" // ROS Default Header File

#include "ros_param/SrvTutorial.h"// SrvTutorial Service File Header (Automatically created after build)

#include <cstdlib> // Library for using the "atoll" function

int main(int argc, char **argv) // Node Main Function

{

ros::init(argc, argv, "service_client"); // Initializes Node Name

if (argc != 3) // Input value error handling

{

ROS_INFO("cmd : rosrun ros_param service_client_param arg0 arg1");

ROS_INFO("arg0: double number, arg1: double number");

return 1;

}

ros::NodeHandle nh; // Node handle declaration for communication with ROS system

// Declares service client 'service_client_param'

// using the 'SrvTutorial' service file in the 'ros_param' package.

// The service name is 'ros_param_srv'

ros::ServiceClient ros_param_client = nh.serviceClient<ros_param::SrvTutorial>("ros_param_srv");

// Declares the 'srv' service that uses the 'SrvTutorial' service file

ros_param::SrvTutorial srv;

// Parameters entered when the node is executed as a service request value are stored at 'a' and 'b'

srv.request.a = atoll(argv[1]);

srv.request.b = atoll(argv[2]);

// Request the service. If the request is accepted, display the response value

if (ros_param_client.call(srv))

{

ROS_INFO("send srv, srv.Request.a and b: %ld, %ld", (long int)srv.request.a, (long int)srv.request.b);

ROS_INFO("receive srv, srv.Response.result: %ld", (long int)srv.response.result);

}

else

{

ROS_ERROR("Failed to call service ros_param_srv");

return 1;

}

return 0;

}

ros_param 폴더 안에 srv 폴더 생성 후 SrvTutorial.srv nano에디터로 생성

int64 a

int64 b

---

int64 result