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

[Felix Ruess]

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

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

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

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
>>
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