PX4 Vision fly indoor (GPS deny)

Hi, my university bought a Px4 Vision v1.5, and would like to use it for indoor experiments. My question is: is it possible to use only the optical flow (PMW3901), for navigation without gps?
I set the EKF2_AID_MASK parameter to use only the optical flow,
and I activated the SENS_EN_PMW3901, adjusting the position parameters.
But if I try to take off in position mode, the LED starts flashing red and the drone refuses to arm, without giving an error on qgroundcontrol or mavlink inspector.
Do you have any suggestions?
thank you very much, have a nice day

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My question is: is it possible to use only the optical flow (PMW3901), for navigation without GPS?

No, because optical flow measures velocity and therefore if you integrate your velocity to estimate position, you inherently include a drift in the integration process.

What optical flow can do is stabilize your vehicle in GPS denied environments. However, since the position estimates will drift over time, navigating based on optical flow is not really possible.

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I am facing the exactly same question. (My setup is using PMW3901 hex hereflow)

Thanks for opening this discussion and @Jaeyoung-Lim 's response.
I would like to further ask that when EKF2_AID_MASK was set to 2, which flight mode will it function.
I’m curious if i can run the offboard visual source and opticalflow at the same time.

hello, first of all thanks for support.
Yesterday I did some tests and I noticed a bug in the firmware 1.13.3, checking the mavlink inspector, the OPTICAL_FLOW_RAD topic is not generated, this probably was the cause of the “position mode” problems. At the beginning we thought of a hardware problem but in the end it was solved by downgrading to version 1.13.2, we have checked also the 1.13.1 and both working well.
Now I will open a report on github to try to fix the problem.
Sorry if I’ve go offtopic a little bit.
Ascertained that with only optical flow I can’t fly indoors, Do you know of any system that does not require external hardware (e.g. MOCAP) to be able to use the px4 vision indoors?

i’m using
Hardware: PX4_FMU_V6C (V6C01)
Software Version: v1.13.3

do you mean this topic?

yes that topic, at the moment, my colleague has the drone, next week I will try to redo the installation from scratch, I don’t know what could be the problem.

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