Hey Leonard, yeah don't waste too much time on it if you don't think it'll help, but hopefully there's something useful in there. This is the dataflash log from that last flight.
I'm looking forward to getting the last 10% of the handling perfected!
You could try to soften Alt hold by reducing rate P from 6 to 3 and Accel P from 0.6 to 0.4. Hopefully you still have an acceptable Alt_Hold but it might relax your descents a little.
Let us know how you go!!
I installed 3.1.RC7, I resetting the EEPROM and with the default values I run Autotune, everything ok about 4 minutes with no wind, but with the parameters of autotune I like oscillations in the post, I declined STAB P 5.25 autotune value STAB P 4, but the fluctuations are the same lower intensity, I wanted to change the code as I had advised you:
"go to config.h on line 786 You Should see this:
# define STABILIZE_RATE_LIMIT 18000
Change it to this:
# Define STABILIZE_RATE_LIMIT 9000"
but I have not found the line to be replaced, I was obliged what should I change?
Hi Fabio, where did you get the code that you are looking at? I have Trunk open right now, and I found that line in config.h. So you must be using an older version of the code from before this was added?
Thanks Leonard I'll have a play around with those parameters.
I understand that the descent wobble is actually a unfortunate characteristic of the dynamic response of a quadcopter. I havnt done extensive research - but i believe that when descending, there is a pressure region below the copter that oscillates back and forth under the 4 (or 6 or 8 etc) props. It has to do with the fact that the props are descending into their own turbulent prop wash.
the good news is that the arducopter code should be able to deal with this...at a low enough rate of descent. is descending at max rate (1.5 m/s) a requirement of your filming? does the copter behave at lower descent rates?
im sure some predictive control could handle higher descent rates, but until we get a real cpu on board, that kind of advanced control is prolly outside the operating characteristics of arducopter
I just completed my AutoTune on my Y6 and the tail motors pulse a bit and the roll is very sensitive. I have attached the logs and here is the details.
APM 2.6 with ext Mag and GPS
Top CF 10x4.5
Bottom CF 11x4.7
Any guidance on removing the pulsing and lowering the sensitivity on roll would be appreciated.
Houston, we have a problem ...
Oops ... (: Well, I played with autotune on my dedicated "kamikaze" quad and ... it didn't go well. That's ok, that's what that copter is for and I learn more from it than my working others, except that .... I can't figure out what went wrong on this one.
Flown this copter many times on rc5 without issues (alt hold, loiter, rtl, etc ..). After the first two AT induced 15-20 deg rolls, the third one appears to have led to a roll of 90degree+, from which I was unable to recover. Have looked at the logs, can't find an explanation. The only thing I can conclude is maybe excessive vibration? (yet the quad hovers at less than .1g vibration). I can't also rule out mechanical failure of course but should add that motors are fine after the crash, props were broken but not loose, etc ...
GPS, baro, etc ... data seems fine.
Will continues delving into logs but I must be missing something obvious ?
Well, I'm not sure if it's 100% relevant to this, but I tried to auto-tune my hexcopter today and it crashed miserably before I even started: I took off in stabilize, but a few seconds later one of the motors went full throttle and the hexcopter just flipped and went down. No major harm done. The main problem is I don't know what happened. The only thing wrong in the log is apparently a software crash judging by the nonsense in the last log message. The log doesn't show a high motor toward the end, so it was probably not instability - just a crash. Is the latest version (3.1 rc7) known to have bugs? If anyone is inclined to look through the log, please let me known if anything looks amiss.
Well, some prop replacements and it flies again, I feel confident that mechanical or electrical failure was not involved. Alt hold and loiter solid (but not perfect, that’s what auto-tune is for …). I did a bit of (ultimately destructive) testing by flying in stabilize, twitching roll to see how far I could get away with. Wanted to reproduce the problem and I sure did … Turned out after looking at tlogs and dataflash that a fast 25 degrees roll and roll back was ok, but I hit the deck at 30-35 degree . Of course in manual I can’t really judge how fast I was rolling back … And if it is out of tune to start with, there’s no knowing how much is too much … Turns out the copter landed perfectly upside down, no damage. Flew happily after …
Question for Leonard or devs … Isn’t AT inducing 15 degrees max? If so, I don’t understand why the copter flipped on the first try. I saw that roll in was flat on the original failed try, I was not touching the sticks, yet is that expected? About the auto-tune process: does it start with stock or existing P and sets D and I to 0, to then increase P, check for response, then deal with D then I? Wondering if a lower P to start with, in my case, would prevent excessive roll … Also, what is the scoop with transmitter trim, does AT take this into consideration? (I have some on the roll axis … ).
For what it’s worth: “Kamikaze” copter that failed AT is reasonably well-built, though, despite it’s name. 25mm CF arms, 10” center plates. A tad under 2.5kg/5pounds as flown (I typically use it with extra small Go-pro gimbal) , 660mm motor to motor. A tad over powered as flown, throttle hover in mid 400. Flew with stock PIDs.
I really want to make it work … Auto-tune kicks ass and rocks! (Even if I didn’t get it to work so far on that one … ) Separates and clearly makes APM superior to the one size fits all (won’t work imho) closed source WKM (I fly that too) ...
What are the required conditions for Autotune. I've been trying to find a day with little wind over the last 2 or 3 weeks, but can't seem to get anything good when I can get out and tune.
This link shows the wind conditions in my area. Average is around 16km/h, but goes as low as 3 or 4, but as high as about 30km/h http://wind.willyweather.com.au/wa/peel/westfield.html
Obviously I need it to be as calm as possible, but I can't go and tune at 11pm or 2 in the morning, or even 11am cos im at work.
Damn work, always interrupting my hobby time.