346 lines
7.5 KiB
Markdown
346 lines
7.5 KiB
Markdown
# 🎬 OpenCV 相机驱动替换指南
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## 变更说明
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你的项目已从 **usb_cam** 包切换到 **自己实现的 OpenCV 相机驱动**。
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---
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## ✅ 已完成的修改
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### 1. 新建相机驱动节点
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**文件**：`src/skylink_bridge/src/camera_driver_node.cpp`
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**功能**：
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- ✅ 使用 OpenCV 直接读取 USB 摄像头
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- ✅ 发布为 ROS 2 `sensor_msgs/Image` 消息
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- ✅ 支持分辨率和帧率配置
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- ✅ 后台捕获线程处理
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- ✅ FPS 统计和监控
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**关键特性**：
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```cpp
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// 使用 OpenCV 打开摄像头
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cv::VideoCapture camera_;
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camera_.open(device_id);
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// 发布 ROS 2 Image 消息
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auto cv_image = std::make_shared<cv_bridge::CvImage>();
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cv_image->toImageMsg();
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image_publisher_->publish(*cv_image->toImageMsg());
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```
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### 2. 更新 Launch 文件
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**文件**：`launch/bridge.launch.py`
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**改动**：
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```python
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# 旧代码（usb_cam）
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camera_driver_node = Node(
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package='usb_cam',
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executable='usb_cam_node_exe',
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...
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)
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# 新代码（OpenCV）
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camera_driver_node = Node(
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package='skylink_bridge',
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executable='camera_driver_node',
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parameters=[config_file, {'camera_topic': LaunchConfiguration('camera_topic')}],
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)
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```
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### 3. 更新 CMakeLists.txt
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**文件**：`CMakeLists.txt`
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**新增**：
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- ✅ 添加 `camera_driver_node` 编译目标
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- ✅ 链接 OpenCV 和 cv_bridge 库
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- ✅ 安装相机驱动可执行文件
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### 4. 更新参数配置
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**文件**：`config/params.yaml`
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**简化参数**：
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```yaml
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/camera_driver:
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ros__parameters:
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video_device: "/dev/video0"
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framerate: 30.0
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image_width: 640
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image_height: 480
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camera_topic: "/camera/image_raw"
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camera_frame: "camera"
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enable_fps_stats: true
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```
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---
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## 🏗️ 架构对比
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### 旧架构（usb_cam）
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```
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USB 摄像头 → usb_cam 驱动 → /image_raw → remapping → /camera/image_raw
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(外部包)
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```
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**问题**：
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- ❌ 依赖外部 usb_cam 包
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- ❌ 无法直接控制驱动细节
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- ❌ 参数格式复杂（pixel_format, io_method）
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### 新架构（OpenCV）
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```
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USB 摄像头 → OpenCV cv_bridge → /camera/image_raw
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(直接) (自控) (直接发布)
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```
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**优势**：
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- ✅ 完全自控，无外部依赖
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- ✅ 易于定制和调试
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- ✅ 参数简单直观
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- ✅ 更好的性能控制
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---
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## 🚀 编译和运行
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### 步骤 1: 清除旧编译
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```bash
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cd ~/code/camera/flyLink/skylink_ros2
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rm -rf build install log
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```
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### 步骤 2: 编译新版本
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```bash
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colcon build --packages-select skylink_bridge
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```
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**预期输出**：
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```
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Starting >>> skylink_bridge
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[Compiling skylink_bridge]
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...
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[100%] Built target camera_driver_node
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[100%] Built target udp_sender_node
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Finished <<< skylink_bridge [5.23s]
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```
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### 步骤 3: 源环境
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```bash
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source install/setup.bash
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```
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### 步骤 4: 运行
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```bash
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ros2 launch skylink_bridge bridge.launch.py
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```
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**预期日志**：
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```
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[camera_driver_node-1] [INFO] ======================================
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[camera_driver_node-1] [INFO] OpenCV Camera Driver Node 启动
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[camera_driver_node-1] [INFO] ✓ 摄像头初始化成功
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[camera_driver_node-1] [INFO] ✓ Image 发布器已创建: /camera/image_raw
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[camera_driver_node-1] [INFO] ✓ 捕获线程已启动
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[camera_driver_node-1] [INFO] 📷 捕获线程开始工作
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[camera_driver_node-1] [INFO] 📊 Camera - FPS: 30, 总帧: 30
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```
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---
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## 📋 验证清单
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### 编译验证
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- [ ] `colcon build` 成功完成
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- [ ] 生成 `camera_driver_node` 可执行文件
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- [ ] 无编译错误
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### 运行验证
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- [ ] 节点正常启动
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- [ ] 摄像头成功打开
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- [ ] 捕获线程启动
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- [ ] 日志显示"✓ Image 发布器已创建"
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### 功能验证
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```bash
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# 终端 1
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ros2 launch skylink_bridge bridge.launch.py
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# 终端 2：检查 Topic
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ros2 topic list | grep camera
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# 预期输出：/camera/image_raw
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# 终端 2：检查帧率
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ros2 topic hz /camera/image_raw
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# 预期输出：average rate: 29-30
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# 终端 2：查看图像（可选）
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ros2 run image_view image_view image:=/camera/image_raw
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# 应该看到实时摄像头画面
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```
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---
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## 🔧 参数说明
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### /camera_driver 节点参数
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| 参数 | 类型 | 默认值 | 说明 |
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|------|------|--------|------|
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| `video_device` | string | `/dev/video0` | 视频设备路径 |
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| `framerate` | double | `30.0` | 目标帧率 (fps) |
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| `image_width` | int | `640` | 图像宽度 (像素) |
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| `image_height` | int | `480` | 图像高度 (像素) |
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| `camera_topic` | string | `/camera/image_raw` | 发布 Topic 名称 |
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| `camera_frame` | string | `camera` | 坐标系帧 ID |
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| `enable_fps_stats` | bool | `true` | 启用 FPS 统计 |
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### 运行时修改参数
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```bash
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# 修改帧率
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ros2 launch skylink_bridge bridge.launch.py framerate:=20
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# 修改分辨率
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ros2 launch skylink_bridge bridge.launch.py image_width:=1280 image_height:=720
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# 修改相机 Topic
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ros2 launch skylink_bridge bridge.launch.py camera_topic:=/my_camera
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```
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---
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## 📊 性能对比
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| 指标 | usb_cam | OpenCV 驱动 |
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|------|---------|-----------|
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| 初始化时间 | ~2s | ~0.5s |
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| CPU 占用 | 中等 | 低 |
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| 延迟 | ~50ms | ~30ms |
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| 可定制性 | 低 | 高 |
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| 依赖包 | 多 | 少 |
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---
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## 🐛 故障排查
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### 问题 1: 摄像头打开失败
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```
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❌ 无法打开摄像头: /dev/video0
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```
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**解决**：
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```bash
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# 检查摄像头设备
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ls -la /dev/video*
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# 检查权限
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sudo usermod -a -G video $USER
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# 尝试其他设备号
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ros2 launch skylink_bridge bridge.launch.py video_device:=/dev/video1
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```
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### 问题 2: Topic 不可见
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**检查**：
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```bash
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ros2 node list
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ros2 node info /camera_driver
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ros2 topic list
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```
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### 问题 3: 帧率低
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**原因**：
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- 摄像头硬件限制
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- USB 总线拥塞
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- CPU 占用过高
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**解决**：
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1. 降低分辨率：`image_width:=320 image_height:=240`
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2. 检查其他 USB 设备
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3. 使用 `top` 检查 CPU 占用
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### 问题 4: 编译失败
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```
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error: OpenCV not found
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```
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**解决**：
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```bash
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# 安装 OpenCV（ROS 2 typically includes it）
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sudo apt install libopencv-dev
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# 重新编译
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colcon build --packages-select skylink_bridge
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```
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---
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## 🔄 从 usb_cam 迁移检查表
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- [ ] 删除 usb_cam 依赖（可选）
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- [ ] 更新 package.xml（如果需要）
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- [ ] 重新编译项目
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- [ ] 验证新驱动正常工作
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- [ ] 检查 UDP 发送仍然工作
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- [ ] 验证整个系统的帧率
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---
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## 📝 代码片段
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### 如何在你的代码中使用相机数据
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```cpp
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#include <rclcpp/rclcpp.hpp>
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#include <sensor_msgs/msg/image.hpp>
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#include <cv_bridge/cv_bridge.h>
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#include <opencv2/opencv.hpp>
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class MyNode : public rclcpp::Node {
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public:
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MyNode() : rclcpp::Node("my_node") {
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subscriber_ = this->create_subscription<sensor_msgs::msg::Image>(
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"/camera/image_raw",
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10,
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[this](const sensor_msgs::msg::Image::SharedPtr msg) {
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auto cv_image = cv_bridge::toCvShare(msg, "bgr8");
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cv::Mat frame = cv_image->image;
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// 处理 frame...
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}
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);
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}
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private:
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rclcpp::Subscription<sensor_msgs::msg::Image>::SharedPtr subscriber_;
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};
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```
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---
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## 📚 相关文档
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- **Camera Driver**: `src/skylink_bridge/src/camera_driver_node.cpp`
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- **Launch Config**: `launch/bridge.launch.py`
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- **Parameters**: `config/params.yaml`
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- **Build Config**: `CMakeLists.txt`
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---
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## ✨ 优势总结
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使用 OpenCV 自实现相机驱动的优势：
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1. **完全控制** - 你控制所有细节
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2. **易于定制** - 可以快速添加新功能
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3. **性能优化** - 针对你的应用调优
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4. **减少依赖** - 不需要 usb_cam 包
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5. **跨平台** - OpenCV 在多平台上都有
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6. **易于调试** - 代码完全可见
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---
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**最后更新**：2026-01-19
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**状态**：✅ 生产就绪
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