30代エンジニアの備忘録

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

my_interfaces/
├── msg/
│   └── RobotStatus.msg
├── srv/
│   └── SetSpeed.srv
├── action/
│   └── MoveTo.action
├── CMakeLists.txt
└── package.xml

# msg/RobotStatus.msg
string  robot_id        # ロボットの識別子
float32 battery_level   # バッテリー残量（%）
bool    is_moving       # 移動中か否か
int32   error_code      # エラーコード（0=正常）

# srv/SetSpeed.srv
float32 linear_speed   # 直進速度 [m/s]
float32 angular_speed  # 旋回速度 [rad/s]
---
bool    success        # 成功/失敗
string  message        # ステータスメッセージ

# action/MoveTo.action
# ─── Goal（目標指示） ───
float32 target_x
float32 target_y
float32 tolerance     # 到達判定の許容誤差 [m]
---
# ─── Result（最終結果） ───
bool    success
float32 elapsed_time  # 所要時間 [s]
---
# ─── Feedback（途中経過） ───
float32 current_x
float32 current_y
float32 remaining_distance

cmake_minimum_required(VERSION 3.8)
project(my_interfaces)

find_package(ament_cmake REQUIRED)
find_package(rosidl_default_generators REQUIRED)

rosidl_generate_interfaces(${PROJECT_NAME}
  "msg/RobotStatus.msg"
  "srv/SetSpeed.srv"
  "action/MoveTo.action"
)

ament_package()

<?xml version="1.0"?>
<package format="3">
  <name>my_interfaces</name>
  <version>0.0.1</version>
  <description>Custom ROS2 interfaces</description>
  <maintainer email="[email protected]">Your Name</maintainer>
  <license>Apache-2.0</license>

  <buildtool_depend>ament_cmake</buildtool_depend>
  <buildtool_depend>rosidl_default_generators</buildtool_depend>
  <exec_depend>rosidl_default_runtime</exec_depend>
  <member_of_group>rosidl_interface_packages</member_of_group>
</package>

cd ~/ros2_ws
colcon build --packages-select my_interfaces
source install/setup.bash

# インターフェース一覧
ros2 interface list | grep my_interfaces
# my_interfaces/msg/RobotStatus
# my_interfaces/srv/SetSpeed
# my_interfaces/action/MoveTo

# 詳細確認
ros2 interface show my_interfaces/msg/RobotStatus

# デフォルト値を確認
ros2 interface proto my_interfaces/msg/RobotStatus
# robot_id: ''
# battery_level: 0.0
# is_moving: false
# error_code: 0

<depend>my_interfaces</depend>

# status_publisher.py
import rclpy
from rclpy.node import Node
from my_interfaces.msg import RobotStatus  # カスタムメッセージをインポート


class StatusPublisher(Node):

    def __init__(self):
        super().__init__('status_publisher')
        self.pub = self.create_publisher(RobotStatus, 'robot_status', 10)
        self.timer = self.create_timer(1.0, self.publish_status)

    def publish_status(self):
        msg = RobotStatus()
        msg.robot_id = 'robot_001'
        msg.battery_level = 85.5
        msg.is_moving = True
        msg.error_code = 0
        self.pub.publish(msg)
        self.get_logger().info(f'Battery: {msg.battery_level:.1f}%')


def main(args=None):
    rclpy.init(args=args)
    rclpy.spin(StatusPublisher())
    rclpy.shutdown()

# speed_service.py
import rclpy
from rclpy.node import Node
from my_interfaces.srv import SetSpeed  # カスタムサービスをインポート


class SpeedServer(Node):

    def __init__(self):
        super().__init__('speed_server')
        self.srv = self.create_service(
            SetSpeed, 'set_speed', self.callback)

    def callback(self, request, response):
        if abs(request.linear_speed) > 1.0:
            response.success = False
            response.message = 'linear_speed must be <= 1.0 m/s'
            return response
        self.get_logger().info(
            f'Speed set: linear={request.linear_speed} angular={request.angular_speed}')
        response.success = True
        response.message = 'OK'
        return response


def main(args=None):
    rclpy.init(args=args)
    rclpy.spin(SpeedServer())
    rclpy.shutdown()

# インターフェースパッケージ一覧
ros2 interface packages

# よく使うパッケージと型
# std_msgs      → String, Float32, Int32, Bool, Header
# geometry_msgs → Twist, Pose, Point, Quaternion, Vector3
# sensor_msgs   → Image, LaserScan, Imu, JointState
# nav_msgs      → Odometry, Path, OccupancyGrid

# 詳細確認
ros2 interface show geometry_msgs/msg/Twist