[ROS 2]027: 토픽, 서비스, 액션 인터페이스

https://cafe.naver.com/openrt/24629

1. ROS 2 인터페이스 (interface) 신규 작성

ROS 2 기초 프로그래밍 예제에서 앞으로 사용할 토픽(Topic), 서비스(Service), 액션(Action) 관련 ROS 2 인터페이스를 만들어 보자.

msg 인터페이스 1개, srv 인터페이스 1개, action 인터페이스 1개를 포함시켜 msg_srv_action_interface_example 이라는 이름의 패키지를 만들 것이다.

2. 인터페이스 패키지 만들기

$ cd ~/ros2_ws/src
$ ros2 pkg create --build-type ament_cmake msg_srv_action_interface_example
$ cd msg_srv_action_interface_example
$ mkdir msg srv action

2.1 ArithmeticArgument.msg 작성
-저장 위치: msg_srv_action_interface_example/msg

$ cd ~/ros2_ws/src/msg_srv_action_interface_example/msg
$ gedit ArithmeticArgument.msg

-파일 내용

# Messages
builtin_interfaces/Time stamp
float32 argument_a
float32 argument_b

2.2 ArithmeticOperator.srv 생성
-저장 위치: msg_srv_action_interface_example/srv

$ cd ~/ros2_ws/src/msg_srv_action_interface_example/srv
$ gedit ArithmeticOperator.srv

-파일 내용

# Constants
int8 PLUS = 1
int8 MINUS = 2
int8 MULTIPLY = 3
int8 DIVISION = 4

# Request
int8 arithmetic_operator
---
# Response
float32 arithmetic_result

2.3 ArithmeticChecker.action 생성
-저장 위치: msg_srv_action_interface_example/action

$ cd ~/ros2_ws/src/msg_srv_action_interface_example/action
$ gedit ArithmeticChecker.action

-파일 내용

# Goal
float32 goal_sum
---
# Result
string[] all_formula
float32 total_sum
---
# Feedback
string[] formula

3. 패키지 설정 파일 (package.xml)

원래 파일 내용

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>msg_srv_action_interface_example</name>
  <version>0.0.0</version>
  <description>TODO: Package description</description>
  <maintainer email="hcw@todo.todo">hcw</maintainer>
  <license>TODO: License declaration</license>

  <buildtool_depend>ament_cmake</buildtool_depend>

  <test_depend>ament_lint_auto</test_depend>
  <test_depend>ament_lint_common</test_depend>

  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>

수정

<?xml version="1.0"?>
<?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org/2001/XMLSchema"?>
<package format="3">
  <name>msg_srv_action_interface_example</name>
  <version>0.2.0</version>
  <description>
    ROS 2 example for message, service and action interface
  </description>
  <maintainer email="hcw@todo.todo">hcw</maintainer>
  <license>Apache 2.0</license>
  
  <author email="hcw@todo.todo">hcw</author>
  <author email="routiful@gmail.com">Darby Lim</author>
  
  <buildtool_depend>ament_cmake</buildtool_depend>
  <buildtool_depend>rosidl_default_generators</buildtool_depend>
  
  <exec_depend>builtin_interfaces</exec_depend>
  <exec_depend>rosidl_default_runtime</exec_depend>
  
  <member_of_group>rosidl_interface_packages</member_of_group>
  
  <export>
    <build_type>ament_cmake</build_type>
  </export>
</package>

4. 빌드 설정 파일(CMakeLists.txt)

원래 파일 내용

cmake_minimum_required(VERSION 3.5)
project(msg_srv_action_interface_example)

# Default to C99
if(NOT CMAKE_C_STANDARD)
  set(CMAKE_C_STANDARD 99)
endif()

# Default to C++14
if(NOT CMAKE_CXX_STANDARD)
  set(CMAKE_CXX_STANDARD 14)
endif()

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  add_compile_options(-Wall -Wextra -Wpedantic)
endif()

# find dependencies
find_package(ament_cmake REQUIRED)
# uncomment the following section in order to fill in
# further dependencies manually.
# find_package(<dependency> REQUIRED)

if(BUILD_TESTING)
  find_package(ament_lint_auto REQUIRED)
  # the following line skips the linter which checks for copyrights
  # uncomment the line when a copyright and license is not present in all source files
  #set(ament_cmake_copyright_FOUND TRUE)
  # the following line skips cpplint (only works in a git repo)
  # uncomment the line when this package is not in a git repo
  #set(ament_cmake_cpplint_FOUND TRUE)
  ament_lint_auto_find_test_dependencies()
endif()

ament_package()

수정

# Set minimum required version of cmake, project name and compile options
cmake_minimum_required(VERSION 3.5)
project(msg_srv_action_interface_example)

if(NOT CMAKE_CXX_STANDARD)
  set(CMAKE_CXX_STANDARD 14)
endif()

if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wpedantic")
endif()

# Find and load build settings from external packages
find_package(ament_cmake REQUIRED)
find_package(builtin_interfaces REQUIRED)
find_package(rosidl_default_generators REQUIRED)

# Declare ROS messages, services and actions
set(msg_files
  "msg/ArithmeticArgument.msg"
)

set(srv_files
  "srv/ArithmeticOperator.srv"
)

set(action_files
  "action/ArithmeticChecker.action"
)

rosidl_generate_interfaces(${PROJECT_NAME}
  ${msg_files}
  ${srv_files}
  ${action_files}
  DEPENDENCIES builtin_interfaces
)

# Macro for ament package
ament_export_dependencies(rosidl_default_runtime)
ament_package()

5. 빌드하기

$ cd ~/ros2_ws
$ colcon build --symlink-install --packages-select msg_srv_action_interface_example