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Function Introduction

The hobot_usb_cam collects image data from a USB camera and publishes it as ROS standard image messages or zero-copy (hbmem) image messages for other modules that need to use the image data to subscribe to.

Bill of Materials

Number	Name	Manufacturer	Reference Link
1	USB Camera	Multiple Manufacturers	Self-selection
2	RDK X3	Multiple Manufacturers	Click Here

Instructions for Use

Hardware Assembly

Connect the USB camera to the USB slot on the RDK.

Install the Package

After starting the RDK, connect to the RDK via terminal or VNC, copy and run the following command on the RDK system to install the relevant nodes.

tros foxy:

sudo apt update
sudo apt install -y tros-hobot-usb-cam

tros humble:

sudo apt update
sudo apt install -y tros-humble-hobot-usb-cam

Publish Images using USB Camera

Run the following command in the terminal of the RDK system to start the connected camera:

tros foxy:

# Configure the tros.b environment:
source /opt/tros/setup.bash
# Launch with specified USB camera device name /dev/video8
ros2 launch hobot_usb_cam hobot_usb_cam.launch.py usb_video_device:=/dev/video8

tros humble:

# Configure the tros.b humble environment:
source /opt/tros/humble/setup.bash
# Launch with specified USB camera device name /dev/video8
ros2 launch hobot_usb_cam hobot_usb_cam.launch.py usb_video_device:=/dev/video8

hobot_usb_cam.launch.py configures default output of MJPEG format images with a resolution of 640x480, and publishes to the topic named /image.

To use other resolutions, you can specify them in the launch command, for example, to publish 1920x1080 resolution MJPEG format images: ros2 launch hobot_usb_cam hobot_usb_cam.launch.py usb_video_device:=/dev/video8 usb_image_width:=1920 usb_image_height:=1080.

If the following information is output, it indicates that the node has been successfully launched:

[INFO] [launch]: All log files can be found below /root/.ros/log/2023-07-18-18-30-54-961749-ubuntu-16326
[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [hobot_usb_cam-1]: process started with pid [16328]
[hobot_usb_cam-1] If you need calibration msg, please make sure the calibration file path is correct and the calibration file exists!
[hobot_usb_cam-1] [WARN] [1689676255.349211776] [hobot_usb_cam]: get camera calibration parameters failed
[hobot_usb_cam-1] [WARN] [1689676255.349432974] [hobot_usb_cam]: Start to open device /dev/video8.
[hobot_usb_cam-1] [WARN] [1689676255.596271213] [hobot_usb_cam]: Open & Init device /dev/video8 success.

View Effect

Here we use the web interface to visualize the image. Open a new terminal for publishing the web service.

In a new terminal, start the following commands:

tros foxy:

source /opt/tros/local_setup.bash
# Start websocket
ros2 launch websocket websocket.launch.py websocket_image_topic:=/image websocket_only_show_image:=true

tros humble:

source /opt/tros/humble/local_setup.bash
# Start websocket
ros2 launch websocket websocket.launch.py websocket_image_topic:=/image websocket_only_show_image:=true

Open a web browser on the same network computer, visit the IP address (type http://IP:8000 in the browser, where IP is the Horizon RDK IP address), then click on Web Display on the top left to see the real-time image output from the USB camera:

API Description

Topics

Published Topics

Name	Message Type	Description
/camera_info	sensor_msgs/msg/CameraInfo	Camera intrinsics topic published based on the camera calibration file set
/image_raw	sensor_msgs/msg/Image	Periodically published image topic in JPEG format
/hbmem_image	hbm_img_msgs/msg/HbmMsg1080P	Image topic based on shared memory, in JPEG format

Parameters

Parameter Name	Description	Type	Supported Configurations	Required	Default Value
frame_id	Message identifier	string	Set the frame_id as needed	No	"default_usb_cam"
framerate	Frame rate	int	Choose as per sensor support	No	30
image_height	Image height resolution	int	Choose as per sensor support	No	640
image_width	Image width resolution	int	Choose as per sensor support	No	480
io_method	IO method for obtaining images from USB camera	string	mmap/read/userptr	No	"mmap"
pixel_format	Image encoding format for publishing	string	"mjpeg,mjpeg2rgb,rgb8,yuyv,yuyv2rgb,uyvy,uyvy2rgb,m4202rgb,mono8,mono16,y102mono8"	No	"mjpeg"
video_device	Device driver name	string	Device name usually as /dev/videox	No	"/dev/video0"
zero_copy	Image transmission mode, enabling shared_mem will use zero-copy mechanism for transmission	bool	True/False	No	"True"
camera_calibration_file_path	Path to store the camera calibration file	string	Configure according to the actual camera calibration file path	No	"/opt/tros/${TROS_DISTRO}/lib/hobot_usb_cam/config/usb_camera_calibration.yaml"

FAQs

1. How to set the video_device parameter?

   After connecting the USB camera to RDK, a new device number will appear, such as /dev/video8. Use this device number as the video_device parameter.Additionally, this Node supports automatic adaptation of device numbers. If set incorrectly, it will automatically adapt at runtime.

2. Will the absence of a camera calibration file affect camera functionality?

   It will not affect.

   If there is no camera calibration file, the camera intrinsic parameters cannot be published, but it will not affect the image acquisition and publishing functions.

3. Is the setting of pixel_format correct?

   [hobot_usb_cam-1] [WARN] [1705548544.174669672] [hobot_usb_cam]: This devices supported formats:
   [hobot_usb_cam-1] [WARN] [1705548544.174844917] [hobot_usb_cam]:        Motion-JPEG: 640 x 480 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.174903166] [hobot_usb_cam]:        Motion-JPEG: 1920 x 1080 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.174950581] [hobot_usb_cam]:        Motion-JPEG: 320 x 240 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.174996788] [hobot_usb_cam]:        Motion-JPEG: 800 x 600 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175043412] [hobot_usb_cam]:        Motion-JPEG: 1280 x 720 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175089161] [hobot_usb_cam]:        Motion-JPEG: 1024 x 576 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175135035] [hobot_usb_cam]:        YUYV 4:2:2: 640 x 480 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175180325] [hobot_usb_cam]:        YUYV 4:2:2: 1920 x 1080 (5 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175226449] [hobot_usb_cam]:        YUYV 4:2:2: 320 x 240 (30 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175272365] [hobot_usb_cam]:        YUYV 4:2:2: 800 x 600 (20 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175318697] [hobot_usb_cam]:        YUYV 4:2:2: 1280 x 720 (10 Hz)
   [hobot_usb_cam-1] [WARN] [1705548544.175365195] [hobot_usb_cam]:        YUYV 4:2:2: 1024 x 576 (15 Hz)
   

   a. Query the supported image formats of the usb camera, as shown in the above log, which displays support for MJPEG and YUYV; b. Modify the configuration of pixel_format, but it must be a format supported by the usb camera, otherwise hobot_usb_cam will exit.