Re: [Paparazzi-devel] rotorcraft / throttle sensitivity / rate mode

[Oswald Berthold]

hey,

thx for all the feedback so far. briefly commenting inline ..

Felix Ruess writes:

> Hi again,
>
> Regarding motors spinning up when disarming via zero throttle full yaw:
> We could probably add something that doesn't pass through the yaw command
> if you have zero throttle in the read_rc functions...
> Added an issue/feature request for that:
> https://github.com/paparazzi/paparazzi/issues/736

cool.

> Regarding yaw behavior, are you talking about rate or attitude mode?

ATT

> In attitude mode, the yaw stick "simply" changes the yaw setpoint with a
> maximum rate of STABILIZATION_ATTITUDE_SP_MAX_R at full yaw stick.
> This yaw setpoint is then passed to the attitude reference model (roughly
> meaning it will "smooth" your attitude setpoint and calculate reference
> rates and accelerations to reach that attitude setpoint). The main
> parameter to adjust the "speed" of the yaw reference
> is STABILIZATION_ATTITUDE_REF_OMEGA_R.

> You can also look at increasing STABILIZATION_ATTITUDE_REF_MAX_R so that
> this limit doesn't really come into effect.
> We could probably remove the REF_MAX_x parameters as in most cases they
> should not really be used (meaning it should be set such that they actually
> don't limit it).
> Already discussed here: https://github.com/paparazzi/paparazzi/pull/663

i briefly varied these settings this morning and it seems to go into the
right direction. so in short, you do a bit more work than simply rate
controlling yaw in ATT? (i'll need to do more experimenting, try RATE
etc.).

cheers, opt

>
>
> Cheers, Felix
>
>
> On Sun, Jun 1, 2014 at 12:44 PM, Felix Ruess <address@hidden> wrote:
>
>> Hi Oswald,
>>
>> I'm not familiar with your ESCs, but if they expect a fixed 1000-2000us it
>> should work just fine.
>> Just set it accordingly in your servos section.
>>
>> The most annoying ones are the ones that do some sort of
>> "auto-calibration" on startup, where you have to give full throttle first
>> and than take this value as their internal maximum...
>>
>> Cheers, Felix
>>
>>
>> On Sun, Jun 1, 2014 at 12:46 AM, Oswald Berthold <
>> address@hidden> wrote:
>>
>>>
>>> hi felix,
>>>
>>> thanks for the nudge.
>>>
>>> turns out the multistars don't do calibration [1], so i swapped them for
>>> some other ESCs, now throttle is fine.
>>>
>>> spent some time playing with the attitude params. horizontal is fine but
>>> yaw behaviour irritates me.
>>>  - very weak response build-up to yaw stick and equally slow decay of
>>>    yaw response (still yawing on when stick is back to zero).
>>>  - thrust is diminished strongly during yaw
>>>  - during disarm (full yaw, throttle neutral) motors spin up and frame
>>>    tends to jump
>>>
>>> i couldn't find any setting for PSI_[PID]GAIN where this would really go
>>> away.
>>>
>>> i'm on git master and using essentially
>>> examples/quadrotor_lisa_m_2_pwm_spektrum.xml
>>>
>>> bst, oswald
>>>
>>>
>>> [1] they seem to have worked quite well with a multiwii type system (for
>>> which the tx travel is adjusted to precisely 1000-2000us).
>>>
>>>
>>> Felix Ruess writes:
>>>
>>> > Hi Oswald,
>>> >
>>> > this very much sounds like you either need to calibrate your ESCs and/or
>>> > set up the min,neutral,max properly in your servo section.
>>> > The neutral value should be the pulse length in us at which your ESCs
>>> turn
>>> > the motors on, but at an acceptable idle speed. Min is off in that case
>>> and
>>> > max is well, max...
>>> >
>>> > This has nothing to do with the gains or anything like that at this
>>> > point... first you need to make sure that if you send the "neutral"
>>> value
>>> > all motors will rotate at idle speed and reach their maximum speed at
>>> max
>>> > and not before.
>>> >
>>> > I never use rate mode, but the ahrs (attitude estimation) should run as
>>> > normal... and works as expected here...
>>> > Can you provide some more details?
>>> >
>>> > Cheers, Felix
>>> >
>>> >
>>> > On Tue, May 27, 2014 at 10:45 AM, Oswald Berthold <
>>> > address@hidden> wrote:
>>> >
>>> >>
>>> >> dear list,
>>> >>
>>> >> i am very glad finally having a real paparazzi system for work and
>>> >> play. as you're already suspecting, i have some questions.
>>> >>
>>> >> system:
>>> >>  - quadrotor, X configuration
>>> >>  - lisa/m v2
>>> >>  - orange rx satellite
>>> >>  - turnigy multistar 20A ESCs
>>> >>  - git 82d414d8 .. (20140520)
>>> >>
>>> >> throttle issue:
>>> >>  1. arming starts the motors but i have to keep them alive by giving
>>> >>    some more throttle, otherwise some of them starve. igains are zero
>>> >>    for the attitude controller. i cannot raise "neutral" because of the
>>> >>    next subissue
>>> >>  2. i have been able to make a first flight with my provisional PID
>>> >>    settings and throttle seems oversensitive. quad takes off with maybe
>>> >>    20% of stick and it was quite a challenge to hover manually.
>>> >>
>>> >> rate mode issue:
>>> >>  - when i alternatively configure rate mode for switch 1 manual, the
>>> PFD
>>> >>    doesn't work. is attitude estimation disabled in rate mode? also, in
>>> >>    messages i see that the phi/theta/psi ests are not updated.
>>> >>
>>> >> regards and thanks for any feedback,
>>> >> opt