前言

usb_cam功能包簡(jiǎn)介

為了豐富機(jī)器人與外界的交互方式，已經(jīng)增加了與機(jī)器人的語(yǔ)音交互方式，不僅使機(jī)器人能夠說(shuō)話發(fā)聲，還能聽(tīng)懂我們說(shuō)的話，但是如果只有語(yǔ)音交互的話機(jī)器人就是一個(gè)盲人，無(wú)法看到這個(gè)色彩斑斕的大千世界，因此我們就需要為機(jī)器人增加視覺(jué)識(shí)別功能。

現(xiàn)在市面上最常見(jiàn)的還是USB攝像頭，物美價(jià)廉，要想使USB攝像頭在ROS下正常工作，我們就需要一個(gè)軟件包來(lái)支持，現(xiàn)在ROS下最常用的usb攝像頭軟件包就是usb_cam了，簡(jiǎn)單理解該軟件包就是V4L(Video for Linux)USB攝像頭驅(qū)動(dòng)在ROS在的一個(gè)移植版本。

截止到目前為止該軟件包在indigo和jade版本上還處于維護(hù)狀態(tài)，對(duì)于kinetic版本及其以上還未有維護(hù)，當(dāng)然雖然沒(méi)有維護(hù)但是在kinetic版本上也可以工作。

usb_cam 功能包下載與編譯

系統(tǒng)環(huán)境：ubuntu20.04
ROS版本：noetic

usb_cam功能包可以通過(guò)github下載

git clone https://github.com/bosch-ros-pkg/usb_cam.git usb_ca

下載完成后提示：

正克隆到 ‘usb_cam’…
remote: Enumerating objects: 2232, done.
remote: Counting objects: 100% (2232/2232), done.
remote: Compressing objects: 100% (1015/1015), done.
remote: Total 2232 (delta 1033), reused 2082 (delta 988), pack-reused 0
接收對(duì)象中: 100% (2232/2232), 843.71 KiB | 306.00 KiB/s, 完成.

處理 delta 中: 100% (1033/1033), 完成.

拷貝到自己的ROS工作空間進(jìn)行編譯

catkin_make

編譯報(bào)錯(cuò)：

— Checking for module ‘libv4l2’
— No package ‘libv4l2’ found
CMake Error at /usr/share/cmake-3.16/Modules/FindPkgConfig.cmake:463 (message):
A required package was not found
Call Stack (most recent call first):
/usr/share/cmake-3.16/Modules/FindPkgConfig.cmake:643 (_pkg_check_modules_internal)
usb_cam/CMakeLists.txt:10 (pkg_check_modules)

原因就是在usb_cam功能包的CMakeLists.txt的第10行是：

pkg_check_modules(video4linux libv4l2 REQUIRED)

系統(tǒng)中沒(méi)有找到這個(gè)包，所以報(bào)錯(cuò)了。

sudo apt-get install libv4l2-dev

出現(xiàn)無(wú)法定位軟件包，則需要更換鏡像源

我換了源也不行，可能換源沒(méi)有成功

sudo apt-get install libv4l-dev

成功了

獲取:1http://mirrors.aliyun.com/ubuntufocal/main amd64 libv4l2rds0 amd64 1.18.0-2build1 [15.8 kB]
獲取:2http://mirrors.aliyun.com/ubuntufocal/main amd64 libv4l-dev amd64 1.18.0-2build1 [108 kB]
已下載 124 kB，耗時(shí) 1秒 (221 kB/s)
正在選中未選擇的軟件包 libv4l2rds0:amd64。
(正在讀取數(shù)據(jù)庫(kù) … 系統(tǒng)當(dāng)前共安裝有 361571 個(gè)文件和目錄。)
準(zhǔn)備解壓 …/libv4l2rds0_1.18.0-2build1_amd64.deb …
正在解壓 libv4l2rds0:amd64 (1.18.0-2build1) …
正在選中未選擇的軟件包 libv4l-dev:amd64。
準(zhǔn)備解壓 …/libv4l-dev_1.18.0-2build1_amd64.deb …
正在解壓 libv4l-dev:amd64 (1.18.0-2build1) …
正在設(shè)置 libv4l2rds0:amd64 (1.18.0-2build1) …
正在設(shè)置 libv4l-dev:amd64 (1.18.0-2build1) …
正在處理用于 libc-bin (2.31-0ubuntu9.9) 的觸發(fā)器 …

再次編譯

catkin_make

順利成功

攝像頭選擇

攝像頭要選擇：

?usb 接口

?支持免驅(qū)協(xié)議:USB Video Class (UVC)

?支持的操作系統(tǒng)：Linux with UVC （above linux-2.6）

連接攝像頭

首先先通過(guò) 下面指令看下本地是否有攝像頭，有幾個(gè)

ls /dev/video*

所以再連接攝像頭后，會(huì)掛載到 /dev/video4下面

修改usb_cam功能包下面的config文件夾下的 usb_cam.yml文件中的

video_device: /dev/video0

改為

video_device: /dev/video4

啟動(dòng)功能包

roslaunch usb_cam test_img_view.launch

實(shí)際場(chǎng)景：

采集到的攝像頭圖像：

查看下當(dāng)前topic

rostopic list

/image_view/output
/image_view/parameter_descriptions
/image_view/parameter_updates
/rosout
/rosout_agg
/usb_cam/camera_info
/usb_cam/image_raw
/usb_cam/image_raw/compressed
/usb_cam/image_raw/compressed/parameter_descriptions
/usb_cam/image_raw/compressed/parameter_updates
/usb_cam/image_raw/compressedDepth
/usb_cam/image_raw/compressedDepth/parameter_descriptions
/usb_cam/image_raw/compressedDepth/parameter_updates
/usb_cam/image_raw/theora
/usb_cam/image_raw/theora/parameter_descriptions
/usb_cam/image_raw/theora/parameter_updates

輸出頻率為30hz

rostopic hz /usb_cam/image_raw/theora
subscribed to [/usb_cam/image_raw/theora]
average rate: 32.730
min: 0.000s max: 0.041s std dev: 0.01037s window: 33
average rate: 31.137
min: 0.000s max: 0.047s std dev: 0.00844s window: 62
average rate: 30.616
min: 0.000s max: 0.047s std dev: 0.00748s window: 92

可配置參數(shù)

start_service_name: "start_capture" # Defines name suffix for std_srvs::Empty service which restarts suspended streaming
stop_service_name: "stop_capture"  # Defines name suffix for std_srvs::Empty service which suspends camera polling timer


# 改成自己設(shè)備的掛載位置
video_device: /dev/video4      # Device driver's entrypoint
# 根據(jù)自己攝像頭選擇
io_method: mmap           # I/O method
                  # - read - for devices supporting virtual filesystem or block I/O
                  # - mmap - for devices with direct libusb memory mapping
                  # - userptr - for userspace devices supporting userspace pointer exchange
# 圖像編碼格式                
pixel_format: yuyv         # Pixel format for Video4linux device (also selects decoder mode)
                    # https://wiki.videolan.org/YUV#YUV_40_.28I420.2FJ420.2FYV12.29
                    # - yuyv - YUV420
                    # - yuv - synonym for yuyv
                    # - uyvy - UVY240
                    # - yuvmono10 - Monochrome 10-bit pseudo-YUV
                    # - rgb24 - Linear 8-bit RGB
                    # - bgr24 - OpenCV-compatible 8-bit BGR
                    # - grey - Grayscale 8-bit monochrome
                    # - yu12 - YU-reversed YUV420
                    # - mjpeg - FFMPEG decoder, MotionJPEG, for compatible hardware
                    # - h264 - FFMPEG decoder, H.264, for compatible hardware
color_format: yuv422p        # On-chip color representation mode for the input frame encoded by hardware
                    # - yuv422p - YUV422 - default, compatible with most MJPEG hardware encoders
                    # - yuv420p - YUV420 - mandatory for H.264 and H.265 hardware encoders
create_suspended: false       # Instructs the node whether to start streaming immediately after launch
                  # or to wait until the start service will be triggered
full_ffmpeg_log: false       # Allows to suppress warning messages generated by libavcodec, cleans log
camera_name: head_camera      # ROS internal name for the camera, used to generate camera_info message
# 發(fā)布topic中的frame_id
camera_frame_id: head_camera    # Frame ID used to generate coordinate transformations
# 發(fā)布的話題名稱(chēng)
camera_transport_suffix: image_raw # Suffix used by image_transport to generate topic names
camera_info_url: ""         # URI for camera calibration data (likely a YML file obtained from camera_calibration)
# 根據(jù)相機(jī)的參數(shù)設(shè)置圖像的寬、高
image_width: 640          # Frame dimensions, should be supported by camera hardware
image_height: 480
# 發(fā)布頻率
framerate: 30            # Camera polling frequency, Hz (integer)


# Auxiliary camera parameters provided by libv4l2.
  # Names for these parameters are generated automatically according to the intrinsic control names exported by the
  # camera driver. The node queries camera's kernel controller module to determine the parameters that can be set up
  # via ROS. For these parameters the corresponding ROS parameters with identical names are generated under this
  # namespace.
  # See also the comprehensive node output describing parameter names and feasible values for them to be set up here.
  # It is also possible to have a list of the available control names using v4l2-ctl application from v4l2-util package:
  # v4l2-ctl --device=/dev/video -L
intrinsic_controls:         
  focus_auto: true
  exposure_auto_priority: true
  exposure_auto: 3
  white_balance_temperature_auto: true
  power_line_frequency: 1
  ignore: [
    brightness,
    contrast,
    saturation,
    gain,
    sharpness,
    backlight_compensation,
    white_balance_temperature,
    exposure_absolute,
    pan_absolute,
    tilt_absolute,
    focus_absolute,
    zoom_absolute
  ]                # Use this list to enumerate the control names that should be delisted from the camera setup
                  # NOTE: the ROS parameters for the V4L controls supported but listed here would be STILL
                  # generated, but the values WILL NOT BE USED to set up the camera. To affect these controls
                  # once you want to do that, their names should me REMOVED from this list!