Re: [Paparazzi-devel] Roll PGain Help, servos always twitching

[Reto Büttner]

Hi Eddie,

I once had twitching aileron servos at about 1Hz. They twiched only in
AUTO1 and AUTO2, not in manual flight. It was because I modified my
airframe.xml to use the ailerons as airbrakes. I went back to a
standard airframe.xml not having the airbrake function. Then the
twiching was gone.

Good luck flying!

Reto

2010/8/18 Edixon Giraldo <address@hidden>:
> I will take on the air today.  Wish me luck!  Yes indeed, I am having a hard
> time grasping the concept.  I am very new with this system since I have only
> been working on it for a month.  I have learned a lot though, but, I know
> there is still a lot to be learned.  The good thing is that everytime I ask
> a question here, I get guided to the right place to look and that makes
> me figure out things on my own too.  Last night I spent hours playing
> with the different values and commands in the airframe.xml files and
> clarified a lot of things.  That is how I run into the twitching servos and
> just wondered if that is what it causes the oscillations in mid air.  The
> twitch apparently is always there no matter how low the gain is, but,
> like you mentioned I will check that in the air.
>
> Thanks.
>
> Eddie.
>
>> Date: Wed, 18 Aug 2010 08:24:03 +0300
>> From: address@hidden
>> To: address@hidden
>> Subject: Re: [Paparazzi-devel] Roll PGain Help, servos always twitching
>>
>> Eddie,
>>
>> You aren't fully understanding the difference between manual and auto1.
>> Manual you are commanding servo positions. But in Auto1 you are
>> commanding roll/pitch angles. So if you tell the autopilot to try to
>> reach 25 degree roll, and nothing changes, the control laws will
>> probably cause the control surface to twitch trying to get more
>> authority, but trying to not overshoot. This all comes back to what
>> everybody has said, auto1 should be tuned in the air, at a comfortable
>> safety altitude so that you can recover should something go wrong. And
>> on that note, it would probably be best to have a flight buddy to help
>> do tuning. One to fly, and one to monitor GCS.
>>
>> Buzz
>>
>> On 08/18/2010 07:17 AM, Edixon Giraldo wrote:
>> > Hi, I am working on adjusting the roll gain for my aircraft. I have not
>> > flown it yet, but, on the ground I did an rc control test in Auto1 to check
>> > surfaces for correct movement and travel. I have noticed that when 
>> > inputting
>> > roll commands from the radio the servos always twitch. I imagine this is
>> > what causes the oscillations in mid air. I then reduced the gain several
>> > times until I got to 1000 and the servos still were twitching, but, there
>> > was very little travel of the ailevons. What variable am I supposed to
>> > adjust at this point?
>> >
>> > Thanks.
>> >
>> > Eddie.
>> >
>> > Sent from my iPhone
>> > _______________________________________________
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>> > http://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>> >
>>
>>
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