# Unified USB Camera Launch Implementation Plan > **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking. **Goal:** Make both USB camera launch files use one 1280x720 native-MJPEG YAML configuration, with WebSocket as their only behavioral difference. **Architecture:** The base launch owns all camera behavior and loads a single ROS parameter YAML. The WebSocket launch includes the base launch unchanged and adds only the WebSocket include. A minimal CMake file installs both `launch/` and `config/`, replacing reliance on stale install-space symlinks. **Tech Stack:** ROS 2 Humble launch, ROS 2 parameter YAML, ament_cmake, Python `ast`/`unittest`, D-Robotics `hobot_usb_cam` and `websocket` packages. --- ## File Structure - Create `src/car_usb_cam/config/usb_camera.yaml`: sole camera runtime configuration. - Keep `src/car_usb_cam/config/usb_camera_calibration.yaml`: calibration data only. - Modify `src/car_usb_cam/launch/hobot_usb_cam.launch.py`: load YAML and start one camera plus shared-memory environment. - Modify `src/car_usb_cam/launch/hobot_usb_cam_websocket.launch.py`: include the base launch and add WebSocket only. - Create `src/car_usb_cam/CMakeLists.txt`: install launch/config directories and register tests. - Create `src/car_usb_cam/test/test_unified_launch_config.py`: structural regression check. - Append `D:/Programme/agent/projects/yiliao/log.md`: timestamped implementation and verification record. ### Task 1: Add a failing structural regression test **Files:** - Create: `src/car_usb_cam/test/test_unified_launch_config.py` - [ ] **Step 1: Write the failing test** ```python import ast import pathlib import unittest import yaml PACKAGE_ROOT = pathlib.Path(__file__).resolve().parents[1] BASE_LAUNCH = PACKAGE_ROOT / "launch" / "hobot_usb_cam.launch.py" WEB_LAUNCH = PACKAGE_ROOT / "launch" / "hobot_usb_cam_websocket.launch.py" CAMERA_CONFIG = PACKAGE_ROOT / "config" / "usb_camera.yaml" def string_constants(path): tree = ast.parse(path.read_text(encoding="utf-8")) return { node.value for node in ast.walk(tree) if isinstance(node, ast.Constant) and isinstance(node.value, str) } def call_names(path): tree = ast.parse(path.read_text(encoding="utf-8")) names = [] for node in ast.walk(tree): if not isinstance(node, ast.Call): continue if isinstance(node.func, ast.Name): names.append(node.func.id) elif isinstance(node.func, ast.Attribute): names.append(node.func.attr) return names class UnifiedLaunchConfigTest(unittest.TestCase): def test_yaml_defines_final_native_mjpeg_configuration(self): document = yaml.safe_load(CAMERA_CONFIG.read_text(encoding="utf-8")) params = document["hobot_usb_cam"]["ros__parameters"] self.assertEqual(params["video_device"], "/dev/video0") self.assertEqual(params["image_width"], 1280) self.assertEqual(params["image_height"], 720) self.assertEqual(params["framerate"], 30) self.assertEqual(params["pixel_format"], "mjpeg") self.assertEqual(params["io_method"], "mmap") self.assertFalse(params["zero_copy"]) def test_base_launch_owns_the_only_camera_node(self): constants = string_constants(BASE_LAUNCH) self.assertIn("usb_camera.yaml", constants) self.assertEqual(call_names(BASE_LAUNCH).count("Node"), 1) self.assertIn("hobot_usb_cam", constants) def test_web_launch_only_adds_websocket(self): constants = string_constants(WEB_LAUNCH) self.assertIn("hobot_usb_cam.launch.py", constants) self.assertIn("websocket.launch.py", constants) self.assertEqual(call_names(WEB_LAUNCH).count("Node"), 0) for forbidden in ( "hobot_codec", "/image_mjpeg", "yuyv2rgb", "usb_image_width", "usb_image_height", "usb_pixel_format", ): self.assertNotIn(forbidden, constants) if __name__ == "__main__": unittest.main() ``` - [ ] **Step 2: Run it and verify RED** Run: ```bash cd /home/sunrise/yiliao_ws python3 -m unittest src/car_usb_cam/test/test_unified_launch_config.py -v ``` Expected: errors because `config/usb_camera.yaml` does not exist, plus failure because the current WebSocket launch contains codec and camera override literals. ### Task 2: Create the shared runtime YAML and install rules **Files:** - Create: `src/car_usb_cam/config/usb_camera.yaml` - Create: `src/car_usb_cam/CMakeLists.txt` - [ ] **Step 1: Add the shared camera parameter YAML** ```yaml hobot_usb_cam: ros__parameters: camera_calibration_file_path: /home/sunrise/yiliao_ws/src/car_usb_cam/config/usb_camera_calibration.yaml frame_id: default_usb_cam framerate: 30 image_height: 720 image_width: 1280 io_method: mmap pixel_format: mjpeg video_device: /dev/video0 zero_copy: false ``` - [ ] **Step 2: Add reproducible package installation and test registration** ```cmake cmake_minimum_required(VERSION 3.8) project(car_usb_cam) find_package(ament_cmake REQUIRED) install( DIRECTORY config launch DESTINATION share/${PROJECT_NAME} ) if(BUILD_TESTING) find_package(ament_cmake_pytest REQUIRED) ament_add_pytest_test( test_unified_launch_config test/test_unified_launch_config.py ) endif() ament_package() ``` - [ ] **Step 3: Run the test and confirm the remaining failure is the old launch structure** Run the same unittest command. Expected: YAML test passes; WebSocket structure test still fails because the old file contains `hobot_codec` and camera overrides. ### Task 3: Refactor the launch files **Files:** - Modify: `src/car_usb_cam/launch/hobot_usb_cam.launch.py` - Modify: `src/car_usb_cam/launch/hobot_usb_cam_websocket.launch.py` - [ ] **Step 1: Replace the base launch with the YAML-backed camera definition** ```python import os from ament_index_python.packages import get_package_share_directory from launch import LaunchDescription from launch.actions import DeclareLaunchArgument, IncludeLaunchDescription from launch.launch_description_sources import PythonLaunchDescriptionSource from launch.substitutions import LaunchConfiguration from launch_ros.actions import Node def generate_launch_description(): package_share = get_package_share_directory("car_usb_cam") camera_config = os.path.join(package_share, "config", "usb_camera.yaml") return LaunchDescription([ DeclareLaunchArgument( "camera_config", default_value=camera_config, description="ROS parameter file for the USB camera", ), IncludeLaunchDescription( PythonLaunchDescriptionSource( os.path.join( get_package_share_directory("hobot_shm"), "launch", "hobot_shm.launch.py", ) ) ), Node( package="hobot_usb_cam", executable="hobot_usb_cam", name="hobot_usb_cam", parameters=[LaunchConfiguration("camera_config")], arguments=["--ros-args", "--log-level", "warn"], ), ]) ``` - [ ] **Step 2: Replace the WebSocket launch with a base include plus WebSocket include** ```python import os from ament_index_python.packages import get_package_share_directory from launch import LaunchDescription from launch.actions import IncludeLaunchDescription from launch.launch_description_sources import PythonLaunchDescriptionSource def generate_launch_description(): camera_launch = IncludeLaunchDescription( PythonLaunchDescriptionSource( os.path.join( get_package_share_directory("car_usb_cam"), "launch", "hobot_usb_cam.launch.py", ) ) ) websocket_launch = IncludeLaunchDescription( PythonLaunchDescriptionSource( os.path.join( get_package_share_directory("websocket"), "launch", "websocket.launch.py", ) ), launch_arguments={ "websocket_image_topic": "/image", "websocket_image_type": "mjpeg", "websocket_only_show_image": "True", "websocket_output_fps": "30", }.items(), ) return LaunchDescription([camera_launch, websocket_launch]) ``` - [ ] **Step 3: Run the structural test and verify GREEN** Run: ```bash python3 -m unittest src/car_usb_cam/test/test_unified_launch_config.py -v ``` Expected: all three tests pass. - [ ] **Step 4: Build the package and run package tests** Run: ```bash colcon build --symlink-install --packages-select car_usb_cam colcon test --packages-select car_usb_cam --event-handlers console_direct+ colcon test-result --verbose ``` Expected: build succeeds and `test_unified_launch_config` passes with zero failures. - [ ] **Step 5: Commit implementation** ```bash git add src/car_usb_cam/CMakeLists.txt \ src/car_usb_cam/config/usb_camera.yaml \ src/car_usb_cam/launch/hobot_usb_cam.launch.py \ src/car_usb_cam/launch/hobot_usb_cam_websocket.launch.py \ src/car_usb_cam/test/test_unified_launch_config.py git commit -m "refactor: unify usb camera launch configuration" ``` ### Task 4: Sequential runtime verification **Files:** - Append: `D:/Programme/agent/projects/yiliao/log.md` - [ ] **Step 1: Stop current camera, codec, generic USB camera, and WebSocket processes** Use targeted `pkill -TERM -f` patterns and verify `/dev/video0` is not held with `fuser -v /dev/video0`. - [ ] **Step 2: Start the base launch and verify camera-only behavior** Run `ros2 launch car_usb_cam hobot_usb_cam.launch.py`, then verify: - one `/hobot_usb_cam` node; - `/image` type is `sensor_msgs/msg/CompressedImage`; - decoded image dimensions are 1280x720; - `ros2 topic hz /image` is approximately 30 FPS; - no `/websocket` node and no listener on port 8080. - [ ] **Step 3: Stop the base launch and start the WebSocket launch** Run `ros2 launch car_usb_cam hobot_usb_cam_websocket.launch.py`, then verify the same camera node parameters, image type, dimensions, and FPS. Confirm exactly one `/websocket` node and one listener on port 8080. - [ ] **Step 4: Compare both captured camera parameter sets** Capture `ros2 param dump /hobot_usb_cam` for both runs, normalize volatile output, and use `diff -u`. Expected: no differences. - [ ] **Step 5: Leave the WebSocket launch running and verify `.164` routing** Confirm the webpage receives a 1280x720 frame and `ip route get from 192.168.10.164` returns `dev wlx200db0c3fca5 table 164`. - [ ] **Step 6: Append the dated implementation and verification results to `log.md`** Record changed files, test outputs, both launch measurements, parameter diff result, final process state, and the `.164` route result. --- ## Self-Review - Spec coverage: shared YAML, base include architecture, removal of codec, native MJPEG flow, sequential runtime validation, and single WebSocket difference are all mapped to Tasks 1-4. - Scope: all changes are confined to `car_usb_cam`, its test/install metadata, and the requested local operation log. - Type consistency: both launch variants publish `/image` as `sensor_msgs/msg/CompressedImage`; WebSocket consumes `/image` as `mjpeg`. - Operational constraint: validation explicitly handles exclusive ownership of `/dev/video0`.