Collision Prevention



  • Hi. I'm using a Voxl flight deck with the System Image 3.2.0 / voxl-suite 0.3.4. I want to test collision prevention on this, however I see that this image doesn't support collision prevention.
    Is there any update on this? What are my options? Since I want to enable this feature on my drone for further development.


  • Dev Team

    System image 3.3.0 / Voxl-suite 0.4.6 supports collision prevention using stereo cameras (voxl-dfs-server) and the en_voa flag in /etc/modalai/voxl-vision-px4.conf



  • @Alex-Gardner Thanks for the reply. I updated the image to 3.3.0. I've also set the en_voa flag to true in the configuration file. However when I do the "voxl-vision-px4 -s" to print the obstacle date, I get nothing.
    On checking the services running by voxl-inspect-services, I see that the voxl-dfs -server is enabled but not running. Is there anything else that I need to do?
    Also, I'm able to see the stereo camera output in the rqt image viewer.



  • @Alex-Gardner Also, just to let you know, we have the stereo camera replaced, so we have attempted the stereo calibration once. And we pushed the files to VOXL.
    When I do on - voxl-dfs-server I get this
    voxl-dfs-server

    skip_n_frames: 5
    n_disparity_levels: 48

    Failed to open calibration file: /data/modalai/opencv_stereo_intrinsics.yml

    But the calibaration method that we performed pushes left.yaml and right.yaml files. Is there anything wrong that I'm doing?



  • Update - we were able to push the opencv_intrinsics.yml. But when I do voxl-inspect-services, it still shows dfs server enabled, but not running.



  • Update - we are able to get the obstacle data printed on the terminal. But this only comes when we run the voxl-dfs-server in one terminal and then run voxl-vision-px4 -s in other terminal.
    Do we have to always run voxl-dfs-server in one window for this?


  • Dev Team

    voxl-dfs-server and voxl-vision-px4 should run in the background just fine if they're marked as enabled in voxl-inspect-services. If you boot the voxl and see that dfs server is enabled but not running, then can you paste the output of journalctl -u voxl-dfs-server so we can see why it's aborting



  • @Alex-Gardner its now perfectly running on boot up. Thanks for the help.



  • @Alex-Gardner I want to check the stereo disparity. However, when I do the voxl streamer -c dfs-server, the stream is getting stuck on the the VLC media player. How do I see the disparity output?


  • Dev Team

    The config option is dfs-disparity not dfs-server



  • @Alex-Gardner Different guy, but I followed the same steps as above and am also just getting a black screen on the VLC player for

    voxl-streamer -c dfs-disparity
    

    Everything else seems to be working fine when I run voxl-inspect-services (you can see my status here https://forum.modalai.com/topic/409/obstacle_detection-messages-not-appearing/3).

    I would like to have collision avoidance integrated onto my drone for a time sensitive project, but the documentation for voxl-dfs-server is not yet present and I am out of resources to turn to.


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