Arduplane stabilized mode PID controller

I’m trying to figure out how can I influence stabilized mode parameters. We all know according to the manual we can mess with PID’s for FBWA, Cruise etc. modes, but what influence Stabilized mode exactly ? Copter got a separate stabilize P section, and acc modes normally work that way (Betaflight, Inav - they all got P or P and D values for stabilized modes).
On Arduplane it looks like there is a limited amount of correction the autopilot can deliver. If you need more than “a bit” for stabilization, the plane won’t stabilize. Is it configurable ? And how can I mess with the way the stabilized mode works ? (I mean the aggresivnes of stabilization).
Thanks !

I’m not clear what direction you’re going. Do you want more active stabilization or less?

In stabilized mode you’re basically in manual as long as there is a stick input. The plane will only correct when there is no control input. If you want more stabilization, but less than FBWA, maybe consider acro mode. There are settings for that, but it won’t self level (just like acro on a quad).

With a tuned PID controller and In a mode like FBWA or B the only limit to correction would be the aerodynamics and physical limits of the plane.

I raised the question because in some cases stabilized is not correcting enough. It won’t go back from sharp climb or dive. Even when the trims are not right - stabilized can’t handle it (I know that’s not the point of stabilized). I was asking if there is an equivalent of P gain for Stabilized. It looks like the autopilot doesn’t even use full servo throws to get the plane back to level.

Fair enough. Are you looking for an AS3X style panic button? Maybe test out engaging FBWA from an unusual attitude (and with lots of altitude). I’ve done it with a couple of my wings and it recovered faster than I could.

Stabilized mode doesn’t get a lot of love around here it seems. Most don’t use it. Personally I use manual mode if I want to do the fun stuff, then one of the FBW modes for just zooming around.

I do maiden flights of quite big UAVs and prototypes for a company I work with. Stabilized is a great way to check some stuff - it’s usually safer than manual, especially on windy conditions, stabilized works like a charm. I use it for first few minutes of flight, than switch to manual and deal with the trims, then I go for all other systems. The thing is - stabilized is all you need for those first, most dangerous seconds of flight - I trust it because it uses only acc, still providing me with great stabilization on windy conditions. Bu sometimes it doesn’t work good enough - especially on heavier, larger wings. And that is probably because it needs tuning - but there is no tuning procedure for stabilized in the manual and I have no clue what parameters are assigned to stabilized (there must be some, but that’s the question - are those parameters hidden or linked to other known parameters ?)

That sounds interesting. I’d always assumed that stabilized uses the normal PID loop, but I have nothing to base that on. You have me questioning that now. Like you say, it may be because the plane needs tuning. How different are your final PIDs from default? Are you testing the same (or similar) airframe type? If so, and the PIDs from your previous builds all follow a similar trend, maybe you could bias the tuning on your maiden flight towards your final PIDs. At least the P value anyway.

When spring arrives and I can get back to more flying you may have inspired me to tinker with stabilized mode a bit more. If nothing than to just figure it out a little better.

I usually test similar airframes, but they often don’t behave similar. Sometimes they fly completely differently due to many small factors. And this is the main problem - sometimes Stabilized mode works perfectly eve without a trim, and sometimes it barely works. Hence my question about way to tune it.

That is exactly what I was thinking - but since I don’t know if standard PID’s influence stabilize mode at all, I had to find some knowledge about it first. On other software (beta, silverware, inav, emuflight) the Stabilize behavior is controlled by separate PID loop.

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