This is a discussion re the ArduCopter-3.1 AutoTune feature. A place for people to report successes and failures, ask questions and get answers.
The AutoTune wiki page is here.
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That was strange. Sorry, I would like to be able to just tell you the answer but I can't yet. I have more questions:
-Was the frame identical other than changing the flat battery for a fully charged battery of the same brand and type?
-Is your CG in the correct location and how did you decide what that location is?
-Was there anything at all that changed between flights?
- Can anything move on the frame?
As for the loiter and Stabilize thing. The next release will include some input shaping that will let you make the copter feel very gentle during Stabilized flight but retain the high Stab_P and the precise handling in Loiter.
Leo, I made a video of the second flip and also a picture, the yellow battery is dead weight as I did autotune without gimbal+camera, the compass is in that blue case, here is the video: https://www.youtube.com/watch?v=dy5g-AzIHkg My frame is a disco and set in V config, the loiter with 9.25 as autotune set is very good but fly in stabilize is very agressive, could you beside the problem give me any hint how I could achieve better loiter(not sluggish) as I get with stab at 9.25P?
Were the batteries identical?
Yes.
Autotune has worked awsome for me on two quad frames
Hi Tim,
Most frames are fine, it tends to be camera gimbals with weight hanging off the frame that really does it. However, we also think that the flexible plastic arms on very powerful quads can mess things up, but this may be caused by a couple of problems. If it is one of the other problems we have in mind, the next autotune will fix it.
You won't have a problem with any 3dr frame for autotune. They are all very stiff! The only way you will make a 3dr frame have problems with autotune is to hang a gimbal of it. This is assuming you are using the Y6B motor configuration on the 3dr Y6.
I have a problem in tuning my hex-copter - it's a bit of a beast at 2kg (4.4lb) but quite overpowered - it hovers at 40% throttle or so and it "feels" very sensitive - it reacts immediately to any push on the sticks. I tried to tune it manually and I went with the P from 0.15 to 0.04 and came back to 0.12 as, weirdly enough, toward both extremes it felt more unstable. Today I tried autotune and it tried about the same as I did: reduced the gain from 0.15 to 0.1 (in about 6-7 steps) when it crashed (as I mentioned before, it gets less and less stable for a lower gain). It didn't get a chance to adjust anything else before it crashed.
I am completely stumped on what to do next: both common sense and autotune says that lower gain should result in a more stable frame, but it's not. BTW, the frame is super rigid (talon carbon fiber frame from HK), so that's not an issue.
If you have any idea guys, please let me know what to do - the instability is especially evident (close to crash stage) when the copter is descending.
I'm wondering if the number of loops per second is not sufficiently high for a relatively powerful frame? The same setup works perfect on a quacopter with about the same setup (different, higher kv, but lower upper power motors) but quite underpowered.
Hi Mihai,
Autotune shouldn't cause your copter to crash as it only adjusts the pid gains for a fraction of a second then returns them to what you had before. Can you post a log of your autotune flight so I can see what is happening?
A log of autotune also lets me see what sort of fight response the copter is showing.
Can you also post a couple of photoes of the frame in the configuration it is in when you are trying to tune it.
Hi Leonard,
thank you very much for your willingness to help and to look in other people's logs. I'm attaching the log with the crash - there are three phases in the log: in the first phase autotune is bringing p from 0.15 to about 0.12, then in the mean time it drifted toward the edge of the field, so I brought it back manually, then let autotune to resume, which it did and when p got to 0.10 it crashed (spectacular rolls at the end, followed by GPS loss).
Today I gave manual tune a try and THANK YOU FOR THE ADVICE!!!! Indeed, my problem was not P but rather a D way too small: the default of 0.004 was 3-4 times lower than needed. So while I started with P=0.15 and D=0.004 I ended with P=0.25 and D=0.0140. I didn't touch I (0.08) - I don't think I should. At the end I went outside in 12mph - 15mph winds and I asked for LOITER and it worked GREAT! Despite gusty winds, it held in 2-3 meters without giving me any emotions :-).
To be honest, it seemed that there is actually quite a large range (at least a factor of 2) of P and D values that result in quite a stable system - I'm not sure if there is any other manual option to further refine them, or if I should give autotune another chance from this super-stable position. Advice kindly requested.
Happy Camper,
Mihai
2014-03-11 13-09.log
Hi Mihai,
Sorry mate, you sent the wrong log. There is no autotune here. Can you attach the autotune log?
A quick question, what esc's are you using?
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