[jobybett]

Hi,

so for the last few days I have been trying to dial in my hover, but I seem to be making it worse not better... I've read tones of threads here and the wiki plus several videos on pid tuning and setup, but I can't seem to get it right, attached are my the settings that I just flew with, I seem to have made it even worse this time not better.

In the video I'm completely off stick after about the first 5 seconds, with just the slightest left/right roll every now again to keep it in shot.






I've checked the baro, and its good, scope shows no more than about 1m of change.
ESC's should be calibrated fine, not had problems with that.
I believe that the motors + props should be more than powerful enough, in thrust mode I can rocket into the sky way too fast to this end I tried adjusting the velocity prop lower.
I've also tried adjusting the filters (sensor tuning on the Expert page).

I guess the first question is just how steady a hover should you be able to achieve, maybe I'm being unrealistic?
Second, should I do a full reset of the settings and try again or continue from where I am, stock setting were slightly better than this video, but not what I was expecting.

[NicholasDavid]

No something is not right. The pulsing or surging isn't good. It looks plenty powerful. Smooth sounding minus the surging. I'm not sure what's causing it. My guess it's in the tuning. My only advice would be turn I and D down and start over with P from the beginning. I've never used txpid or easy tune on Libre pilot. I'm sure that's what somebody else is going to recommend. But at least it flys. But it should be smooth and not surging like that.

What defaults did you start with. Try the 400 or 500 defaults and adjust up or down depending on how it handles. I'm less expirenced with these larger copters. Especially with sensors and such. It could easily be something to do with that not setup correctly. Sorry I wish I could be more help.

[Mateusz]

In the UAV file you use

Code: [Select]

            <field values="Basic (Complementary)" name="FusionAlgorithm"/>

which means that only Accelerometer + Gyro is used for stabilization, and additionally baro for altitude hold/vario. Magnetometer and GPS are not used except for showing information.
I would say it's a good start, before enabling INS fusion algorithm.

I would also recommend tuning PIDs, as it seems the quad is overshooting with correction for altitude. I had similar problem and got advice to play with VtolPathFollowerSettings->VerticalPIDs. These are different PIDs than one stabilizing the copter.

All Altitude related PIDs can be tuned with TxPID module, while EasyTune is only for stabilization PIDs.

Does reducing or increasing P gain help ? I would first start increasing and then decreasing. I am not an expert but if your aircraft does not oscillate vertically in Manual thrust mode, then your stabilization PIDs should be fine. I think you should look at vertical PIDs which is a feedback look keeping altitude with baro.

Also you might want to change throttle curve, flattening it a bit in the middle, so you don't have such a sharp response when sticks are centred.

[onecooler]

I have exactly the same behavior of alt vario! Did not have time to dig into yet. However alt hold behaves more solid. If you fix this issue - please let me know.

[jobybett]

Thanks guys, I started with the DJI F450 settings as its a good clone of that frame, but I spec'ed the motors and esc's myself so knew it would not be spot on.

I'll take a look at the VtolPathFollowerSettings->VerticalPIDs I did have a flatter throttle curve at first but after reading that in AltVario it does not really use it, and injects a deadband around center did not bother changing it again after my last reset.

[TheOtherCliff]

The foam over your baro chip is too thick.  This oscillation is common and is usually caused by the wrong foam type (MUST be open cell) or too compressed or just plain too much of it.

The foam stops air turbulence from the props from affecting the reading.  It does it by effectively making a very tiny hole for the air pressure changes to get through.  If that hole is too small (foam too dense), the new air pressure won't register for a while and it e.g. keep climbing, thinking the quad too low.  By the time it starts to register, the quad is too high.  Oscillation.  That is exactly what happens if you use too high a PID for your slow ESC, except you get roll/pitch oscillation.

[jobybett]

Thanks, I'll try that, I had been playing a bit more but it has not made much difference, that would explain it, It came in a case with the foam already attached so I figured it was ok.

If I have it in a case should I use foam as well?

[TheOtherCliff]

A case can help reduce the need for foam; a dome even more so, but you need foam to keep light out too, especially if it is a transparent case like the blue ones that come with clone Revos.

I fly a 500 quad with a dome, a small baro cover, and no foam, but I have tested it and know it works well.