3689567378?profile=originalMy first official foray into 3.1 has not gone well, and so far, Gravity - and his mistress, the hard frozen ground - are winning 2:Nil.

Both bird were flying fine on 3.0.1. There have been no physical changes. The Disco even flew ok on 3.1, pre-autotune, although I still can't seem to find the source of the vibes.

The Disco started autotune no problem, and you could physically see roll getting tighter and tighter. Pitched started, and that looked good too. I was getting excited. Right up the moment it totally flipped out of control, Belly bounced off the tarmac, and proceeded to freak out some more and self-destructing. Logs are attached, and apart from less than satisfactory vibes, no idea why it freaked out. All physical connections were tight even after the crash, and there were no loose screws or bolts. The new 3.1 engine readings look weird btw...something in there, maybe?2014-01-12%2008-25.log2014-01-12%2008-25.log.gpx


So I moved onto the quad, which was even more bizzare. It tried to do a fly away the moment I flicked autotune. So I flicked out, but it now went into failsafe RTL. Broke RTL into loiter, and it freaked out again. Realising this was not a route to safe flight, I went back to stabilise, and discovered I had lost all yaw control. Then I made a mistake - instead of just putting it straight down in stablise, I flicked manual RTL, and boom - all motors stop. Stabilise again, but I was too late. Wish I had the logs for that one, but I think the logs are corrupted - it fails at the same point very shortly after starting the download. As mentioned - It was running sweet in 3.0.1...Compassmot: 0%, Vibes well within +/-5, etc. Only thing changed was the upgrade to 3.1.

2 freakouts in Autotuine on 2 aircraft in the same morning session. Both were flying well previously. Methinks I'll stick to the manual PID method, until my confidence is restored...

Amazingly, both are now phyisically repaired already. Disco ready to fly, and I'm doing a ground up, factory-fresh install on the Quad. The fog has come though, so visibility down to 20m. I had a lot of flight activity planned, but it ended up being a frustrating - and short - weekend's flying :-(

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  • MR60

    Oups that hurts, two crashes the same day. Fortunately no expensive damages.

    I did autotune succesfully on my trainer quad with the Quadro ESC (not SimonK thus).

    I was going to autotune my X8 with SimonK ESCs but now I will not do it anymore, scary.

    In general, I wonder if new features in Arducopter software, like autotune which are not mandatory, shouldn't be held back longer before publication to allow a few selected beta testers to cover all obvious configuration test cases, certainly a SimonK ESCs config which almost everybody uses now in their multicopters.

    Just a thought for a better Arducopter reliability brand/image control.

  • I've done autotune on a disco with a Zippy Compact 4500 battery. It is indeed tail heavy and needs a strong counterweight on the front if you are not using a gopro like me. Usually I can get a good hover and alt hold for AT but it does need some trimming before hand. I've thought about moving the battery under the frame and adding leg extensions but I like the sleekness of the frame as it is. The other option is to get some smaller batteries, maybe 3700 or 3300. Although the Zippy Compact 4500 is a tad bit lighter than the TBS 4500. 

  • Developer

    Hi Euan,

    Well, they have put the CG in the right spot so you are good there. It is almost definitely the wind. I always make a point of turning the axis that is tuning 90 degrees to the wind. That way it is easier to see if airspeed is building up.

    I have no idea how the Multistars will go but I see no reason to think they wouldn't be fine.

    Good luck and let us know how you go!

  • I used AT on TBS Disco Pro without any problem. I use the TBS ESC (AFAIK, SimonK software)

    It is now on rails.

  • @Euan i did the autotune succesfully with the dji 30A opto ESC's

    @Calle let us know your experience!!

    after i change to the afro 30a ESC when ever i turn on autotune my discovery just drops like a rock, i am currently rebuilding after lat crash, waiting for some spares.

  • Im about to do an autotune with my TBS disco as soon as I have reinstalled my APM(in a box with status lights etc). Its a couple of days ahead because of work though. Im running SimonK 20a blue mystery escs that have 50h flight time ie. proven to work. At least with a KK2.

    The problem with the Opto ESCs are under where the motor cables are attached. There are clusters of resistors there that are badly soldered. If they are resoldered it will work. I do not have any info on how the SimonK affects the autotune.. Me and my friends are staying away from the Optos from RCTimer for ahwile.

  • Has anyone else done an autotune on a TBS disco yet, btw?

  • He Leonard,

    Wow - now that's an explanation I can believe! These are 30A rated, but if Calle is correct, they might not be best suited for a 3.1 deployment anyway.

    I might go back to some conventional ESC's then - I have some 30A 4S OPTO Multistars lying around I can use. Would these be ok? They are factory fresh and still in the wrapper.

    Where was this in the logs, btw?

    Re: The asymetrical pitch responses - yes, that matches what I saw - it definitely ptiched backwards more than forwards - I just assumed it was normal, or a wind issue (I tested facing directly into the slight wind).

    The CoG recommendations are on page 20 of the official manual: You can get the CoG right, by pushing the APM right forward. With a 4S 4500 in, there is around 3/4 of an inch of the batter tray still visible. You must fly with a GoPro2...there are numerous forume posts of guys with GP3's having to go with lighter packs to get the CoG forward again.


  • WARNING! We have had several failures with the Opto ESC from RCTimer! Many of them are soldered badly causing the ESC to get out of sync and glitch the motor. We have them on 4 Y6 and 2 quads and had one Y6 go down and one quad. I will start with replacing this ESC if you are using this. You can confirm this by testing each and every ESC separate. Press with a plastic stick on the components starting from the motor side. If it glitches it is bad.. This could actually be the problem for many of you that have crashed your multirotors. Just my 2 cents!

  • Developer

    Hi Euan,

    I am very sorry to see you damaged two copters!

    It looks like you worked out that the first was an electrical problem and nothing to do with Autotune. Autotune may have caused those wires to move around more than normal prompting the crash though.

    The second crash I can confirm that this is a known fault that is caused by Autotune, but not a bug in Autotune. 

    To explain this failure I will quickly describe how Autotune does it's tests. First it sits in Stabilise mode waiting for the airframe to level. Once it has been level for quarter of a second it begins a test. Here Autotune switches STabilise off on the axis it is testing and directly requests a rate or a position on that axis, depending on the test it is doing. As soon as the test is over, or the pilot moves the sticks, Autotune switches back to Stabilise. So except for a very brief moment during each test, Autotune is identical to Stabilise.

    This failure is characterised by the copter losing control immediately after the switch back to stabilise. The loss of control always resembles an ESC failure. In your case it is the front left ESC.

    We suspect that the repeated aggressive pulses of Autotune cause a motor to loose sync or the ESC to get hot. We believe this is more prevalent in Simon K ESC's  because they don't have the filtering on the inputs and therefore get higher current pulses than a non-Simon K ESC. For this reason I think copters using Simon K ESC's should over spec their maximum current.

    The link to one of my posts referring to Autotune as an optional feature to get the most out of a given frame was posted in reply to a user who didn't like my earlier post, thinking autotune was too fussy, my post stated "Things that can make autotune fail include, overly flexible motor arms, overly soft apm vibration mounts, soft mounted camera gimbal, incorrect CG." As you can see, all pretty basic stuff.

    Something I did see in your autotune of the Disco. It had an incredibly asymmetrical response to pitch! The pitch tune should have been over MUCH quicker. It pitches up much faster than down and Autotune couldn't work out which one to believe. You said that you had the CG right on the recommended value. Could you post me the link to the document showing were the CG is for that frame?

    Again, I am very sorry for the crash.

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