Instant Fly-off at arming time ... with MTF-01 Lidar/OpFlow in Angle/AltHold/PosHold & Surface mode

[cramredan1]

I built an iNAV 8.0 Quad with no GPS, fitted with an MFT-01 Lidar/Opflow and Magnetometer, and followed by the line a youtube video explaining the full configuration process :https://www.youtube.com/watch?v=bEKm-PGRnks

Flying modes of my drone are set the following way through an RC switch on my Radio :

• RC/Radio button at position 0 : ANGLE
• RC/Radio button at position 1 : ANGLE + ALTHOLD
• RC/Radio button at position 2 : ANGLE + ALTHOLD + POSHOLD + HEADINGHOLD + SURFACE

• Arming & Flying at Switch Position 1 is perfect and maneuverable (1 meter)
• Switching RC/Radio switch to position 2 puts the flight (more or less) on a stable altitude (1 meter)
• But… Switching to Position 3 triggers a fly-off at highest speed (happily to the ceiling) in less time than I have to Disarm. Crash course !

I checked, rechecked and re-rechecked all parameters, calibration, orientation, and I don’t have a clue of what’s happening.

These are my settings...

and the CLI diff just in case...
INAV_8.0.0_cli_MARC_CRAFT_20250218_202704.txt

Would you have any suggestion that would help identifying the problem ??

[sensei-hacker]

Your modes for position 3 don't make any sense.
Do you want the sticks to control the angle?
Or the position? Or the heading?

Those are three different things.

You're asking the aircraft "please stay level and drift around with the wind, while not moving, and ... What? It can't do two or three different, contradictory, things at once.

That said, a sudden increase in altitude is often caused by the foam falling off the baro, or excessive vibration. Check that the foam is still there and in the right place. Also check that all screws are snug and nothing can flop around.

[cramredan1]

@sensei I don't understand the rationale behind it. These modes are all cumulative and here by design.

If I understand correctly :

. ANGLE ; is the flight mode dedicated to quads
. POSHOLD : prevents the drone from drifting left/right/front/back at no stick input
. ALTHOLD : prevents the quad getting up/down at no stick input
. HEADINGHOLD ; locks the quad on its given orientation North/South/West/East
. SURFACE : adjusts height to terrain level

These modes are also precisely the ones recommended by the manufacturer of the device (MicoAir MTF-01) - Link YouTube video

On the mechanical side, I double-checked and everything is setup and nicely assembled.

I think the problem resides somewhere else. Apparently, the manufacturer suggests using INAV 6.1 or 7.1.2 to people complaining of upfront Fly-offs. Maybe it is not anymore compatible with the INAV 8.0 version I'm usingf. I'll do some tests tonight and provide a feedback to the community asap.

Thanks anyway for your help.

[anti-vaxxer]

RC/Radio button at position 2 : ANGLE + ALTHOLD + POSHOLD + HEADINGHOLD + SURFACE

I don't have such setup, but can you try to use only POSHOLD + SURFACE and tell how it goes.

Here it says that POSHOLD already includes ALTHOLD and HEADING HOLD https://github.com/iNavFlight/inav/wiki/Navigation-modes#nav-poshold---position-hold

[cramredan1]

@anti-vaxxer Thanks for suggesting. I'll try in the next few hours and keep you posted of my results.

[sensei-hacker]

ANGLE ; is the flight mode dedicated to quads

Angle is not specific to quads.
Angle means your sticks control the angle of the craft.
Sticks centered = craft is level. Stick to the left - craft leans to the left.

POSHOLD : prevents the drone from drifting left/right/front/back at no stick input

Position mode means your sticks control the position of the craft. Pushing forward makes the craft go forward. Centering the sticks makes the craft stay in the same place. Moving the left stick forward makes it go up, stick backwards makes it go down.

Note these first two are incompatible.
On a planet that has air, the craft can either move to go to the commanded position, or the commanded angle. Not both. Same if the craft operates in water, sodium hexafluoride, or any other fluid.

ALTHOLD : prevents the quad getting up/down at no stick input

Means your left stick controls the altitude. Note your left stick is already being used by position mode, so again get rid of this

HEADINGHOLD ; locks the quad on its given orientation North/South/West/East

Right stick controls heading. Same as above - position mode is already using all four stick axis.

SURFACE : adjusts height to terrain level

Yes, THIS one modifies either althold or position mode.

You're probably wanting position mode with the surface modifier. That uses up all four stick axis, so you can't also have other modes that do something different with sticks.

Don't forget to check for what could be vibrating, though,.in order to fix the "skyrocketing" issue.

[cramredan1]

Thanks both of you Sensei & Anti-vaxxer for these suggestions and precisions. It definitely makes sense to me.
Just tried another maiden flight tonight:

• [POSHOLD + SURFACE] modes as suggested by Sensei had the quad tilting dangeroulsy forward at takeoff

• [ANGLE + POSHOLD + SURFACE] shown the quad taking-off very smoothly, stable in X/Y, but with height oscillations lead to an out of control fly-out, punching the ceiling once again !

Enoug is enough. downgrading to version 7.1.2 just for a try, in order to be sure it works in that version with MicroAir recommended MTF-01 settings. Will keep you posted.