[karla]

I think the tail behaves just as can be expected with the different P values.
Agree with Cliff, just keep going lowering P, try half it to P = 0.002 or even more
From the point it doesn't oscillate, bring it up to the point it does, and then cut it down.
For now, I would not worry much about main rotor out of balance at some point while it spools up (maybe later).

question: on that workbench you have, can you tell when it wants to lift off or is it totally strapped down?

[nestor81]

hi thanks for the quick reply
 
The oscillations to which you refer, can be produced by the same test bench, the mechanics of the heli has been reviewed several times.
Previously, without the controller, you have not had these oscillations, I will still check everything again and do more tests with your indications

Thanks a lot

[nestor81]

I think the tail behaves just as can be expected with the different P values.
Agree with Cliff, just keep going lowering P, try half it to P = 0.002 or even more
From the point it doesn't oscillate, bring it up to the point it does, and then cut it down.
For now, I would not worry much about main rotor out of balance at some point while it spools up (maybe later).

question: on that workbench you have, can you tell when it wants to lift off or is it totally strapped down?

Hi Karla, as I said to Cliff, thanks for the quick response
 
Your contributions are helping me a lot, for the moment I am learning a lot about something new for me, I just need to put it into practice 

As for the test bench, the heli is fully attached to it, but the throttle level is more or less at the hover point

As soon as I get a more or less correct P value, I will remove the heli from the test bench and continue the adjustments with real flight, if it seems correct to you.

Thanks a lot

[nestor81]

Here again...

I have a big doubt, I started from P = 0.002 and it has oscillations, but after a few seconds it stabilizes, my question is, I have to go up until the oscillations are constant and maintained as the ZN method says, or search just where oscillations start even after it stabilizes?

[karla]

Thats progress!
Well, the way I do it (just my personal preference) is search the point where the oscillations start.
The reason is that usually if you keep it there oscillations gets worse and worse and then it can be impossible to land a Heli safely without a tail damage or worse.
But I think what you experience now is different, first it oscillates a bit and then stabilises nicely.
That is something else. It usually does that while the rotor is spooling up. Do it several times so you are sure that's the case. Then you start increase the P like 50% and see what happens.

[nestor81]

Hello,

I have finally decided to download my heil from my wonderful test bench !!

I have made two videos, with different parameters of P

This first video, with values of P = 300/325/350



And this second video, with values of P = 350/375/400



I do not know if the time in flight of each of them will be enough for you to see the reactions that the heli has, but the instability produced and the lack of exponential configured to facilitate its handling, make the movements of the heli quite aggressive, and for my level, it becomes difficult to handle it.

[TheOtherCliff]

I would put it back on your yaw test table and get the yaw figured out first.  You can clearly see the tail oscillating.  The tail should lock solid and be responsive and do what is expected before moving on.

Do you know that your head speed is correct?  Too slow head speed makes it mushy although to me the roll and pitch looked acceptable but not perfect at 400.

For someone who can fly without stabilization, I recommend adjusting in this order (at flying head speed) because Rate needs Manual throws to be correct, Axislock adds complexity to a correctly tuned Rate, Atti needs Rate tuned first:
- Manual, Manual, Rate adjusting Yaw only PID on rotating stand (or skittering on smooth ground)
- Manual, Manual, Rate in free hovering flight
- Then Rate, Rate, Rate
- Then Atti, Atti, AxisLock

Is there something that you know of that would make your yaw servo slower?  Do you have enough amps available (in your BEC) to drive the servo at full speed against resistance?  It looks like you are driving your yaw servo at 50Hz.  Is is capable of using a faster signal?  Is the servo mount and linkage good and tight (little slop or springiness)?

You could be using say 30 degrees for Attitude mode max bank angle, but you are using the default of 55 (you were using 85).  If it is still too sensitive for you, reduce these.

Did you use a cloud config (config built into the setup program) or did you start from default settings?  I think you started with defaults (as I hope) because I see that the inner loop PID is set to default in both uav files.  I worry a bit because sometimes the canned settings have unexpected changes in them.  I would start from default (or KarlA) settings.  There are several things in settings that can make the tail oscillate, but I don't see any of them.

Does heli yaw still oscillate if you use Rate on Yaw instead of AxisLock?

[karla]

Thanks again for the videos, much easier to see what's going on, yes they are long enough.

I think it was a good time to put the Heli on the floor and try it out, and also wise to mount the four 'learning legs'.
You seem to handle it well and have enough room to test it.

I also think the roll and pitch is pretty okay as is and it seems to spool up and spool down without any imbalances, so vibrations should not be a problem, that is very good news.

But two thing comes to mind.
When I see it hover the head speed seems too low, try to increase it a bit (you can rise the throttle curve and meanwhile lower the collective curve around the hover point).
The tail oscillations should not be there. Check if there are any bindings or resistance when moving the tail rotor pitch. Unhook the tail rotor pitch rod on the servo side and try move it back and forth - it should be as smooth as cutting butter with a hot knife - really! After you have checked that and have increased head speed I think you can try your lower P values again for starters.

I would keep trying on the floor to understand how these changes will effect the behaviour. The reason I would not put it back to the bench is only because I don't have any experience to see what is going on and what needs to be changed on a bench. I think you are doing okay and can handle it, you seem very careful.
I would also keep the current stabilisation modes for now.