[Pertti]

Does VelocityRoam need also GPSAssist?

My flight mode switch settings:
-Flight mode:        VelocityRoam
-Assisted control:  None
-If Assisted control is "GPSAssist", what different does it make?
I managed to hold my drone in position hold very well, but then next day something happened and it started drifting. Also arming is impossible if Assisted control is "GPSAssist" togerther with  VelocityRoam or PositionHold .

I use internal mag and UBlox GPS. Health boxes are green.

[f5soh]

Does VelocityRoam need also GPSAssist?

No,
GPSAssist make sense only for primary stabilization modes like Attitude.
Why add a GPSAssist tag to a flight mode already using GPS ?

https://librepilot.atlassian.net/wiki/display/LPDOC/Gps+assist

Be sure the Mag alarm still ok while motors are running and drawn current.

[TheOtherCliff]

No, GPS Assist just turns on "GPS PositionHold" if the sticks are centered.  VelocityRoam already does exactly that.

[Pertti]

Ok, GPSAssist is now clear to me, thank's for that.
But when switching to VelocityRoam the drone starts moving and must be immediately switched back to Stabilized. As if REVO had a different board levelling parameter set for roaming and stabilized modes. Board levelling calibration has no effect. Should I change board rotation parameters?

[f5soh]

Board rotation or board leveling should be the same, while flying using a primary stabilized mode or gps modes.

What do you mean with "starts moving" ?
Most common issue is magnetometer disturbed with high motors currents around that causes a wrong heading measurement.
With wrong heading the position error is corrected in a wrong direction and result in a "toilet bowling", a increasing circular trajectory around the expected position.

[TheOtherCliff]

Do your mags stay green even when hovering?

Did you make strange adjustments to mag orientation?  Generally (at least to start with) this should always be multiples of 90 degrees.

Did you wait 15 minutes before first takeoff for GPS to download almanac?

[Pertti]

I have not measured mags when hovering, only in the house. It's winter here...maybe I try when it's warmer.
- GPS fix is ok, more than 7 satellites,it takes usually 10-15 minutes
- "starts moving" means a sudden increase in pitch when switching to VelocityRoam and the following increasing speed. Not enough control to stop the moving.

[TheOtherCliff]

Are you using aux mag only (Mag Usage: AuxOnly) (that works best).

What is your AuxMagSettings.BoardRotation / Attitude->Magnetometer->AuxiliaryMagnetometerOrientation
for OP GPSv9 and DJI/Naza GPS/mag it should be 0,0,0
for PixHawk and APM GPS/mag if should be 0,180,0 (or 180,0,180 which is the same thing)

Are you using INS13 (Attitude->Settings->AttitudeEstimationAlgorithm).

[hwh]

...I use internal mag and UBlox GPS....

Unless you have a large quadcopter like a 450 or larger an internal mag is unlikely to work well.  On smaller quads it's almost impossible to avoid the magnetic field from the power wires.  That's why the external mags were created.

[jtrout19]

@ theothercliff

I had to set my naza gps 0 , 0 , 180 to get all zeros.

[TheOtherCliff]

Sounds like you have it mounted with the arrow pointing backwards.    In that case, the 180 yaw is fine.

It is confusing that the cable comes out the front of this GPS.

[Pertti]

I had several frames, this frame weights 34 grams and the whole drone 410 grams.  The actioncam Sjcam M20 is placed in the front because it makes the onboard mag go crazy. Also the powerwires  are drawn ast far from the fc as possible.
This configuration seems to  work properly.

[TheOtherCliff]

Are you flying in the house with a GPS mode?  I have never tried that because I assume it does not work.  I would try it outdoors to see if that helps.

I see an antenna (FPV) close to the GPS.  Switch that off.  Switch off telemetry.  Leave the camera unpowered.  Try to fly outdoors.  If that works, then you just narrow it down to what causes the problem.

[Pertti]

I have not tried to fly GPS in the house yet. How to switch off telemetry? I will test it but now it is - 10 ºC outdoors.

[TheOtherCliff]

Telemetry is off by default.  If you don't have an OpLink on your GCS, you don't have telemetry.