Is Optical Flow enabled?

ArduRover Rover 4.1
1

Hi Everyone,

From the release notes, it appears that optical flow is actually enabled for Rover finally. Is this the case? And if so, where is the parameter? I’m not seeing it

Thanks

2

Not that I’m aware of.

3

I don’t have much to report, so I’ll simply resurrect this topic and hope it’s still relevant for the OP.

Optical flow for Rover is now available in 4.4-dev. I tried it out today with a Hereflow module and can report that it does work. My flow quality numbers fell consistently in the 200-range (of 255 possible), which I take to mean that the sensor is reporting good data.

My flow sensor is only 35cm off the ground, which is quite low - certainly below the 1-2m recommended in the PR, but I can’t find a better place to put it where it will remain protected from impact/potential damage and retain an unobstructed field of view.

I was able to run an auto mission with optical flow as the only EKF_SRCx_VELXY, and it performed only slightly worse than with RTK GPS, so it seems to be working reasonably well. I tried fusing it with GPS, which had a slight positive effect overall.

However, it did not really improve my ability to achieve straight-line navigation between waypoints with the new S-Curve-enabled nav controller. It’s my impression that very responsive vehicles do well with the new nav controller, where slightly sluggish ones can only ever get about as good as they might have under NAVL1 control, and that’s after a significant amount of tuning guesswork.

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4

Dear Yuri_Rage,
Thank you very much for your contribution. Can I ask you a few questions in terms of using optical flow in autonomous mission with weak or non-available GPS signal environment:

  1. Because, at the moment, I dont have the physical Hereflow to test, is there any way for me to test the effect of optical flow in simulation ? (as I tried to manage the EK3_SRC_xx params in simulation assuming we have optical flow source available, but it doesnt work. The boat automatically switch into hold mode and stop during the mission)
  2. To run an auto mission with external source (not GPS module), I can find 2 popular options which are Optical flow (hereflow) and realsense camera T265. while the Realsense cam takes a lot of work to integrate with Ardupilot, can I ask you what are the exceptinal features of realsense cam in compare with hereflow? I am looking forward to your advice before deciding which kind of hardware I should purchase.
    Thank you very much for your support.
5

I have no other optical flow experience other than that which I posted above, so I can’t make any direct comparisons between variants.

There may be a way to simulate optical flow, but I am not familiar with the setup.

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