paparazzi-devel
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Paparazzi-devel] Strange behavior: pitch down when engaging AUTO2,


From: Stephen Dwyer
Subject: Re: [Paparazzi-devel] Strange behavior: pitch down when engaging AUTO2, only after launch.
Date: Sat, 8 Sep 2012 20:51:09 -0600

Hello,

Would anyone be willing to post their logs for these flights
somewhere, and make a note around what time in the log the behaviour
occurs?

Thanks,
-Stephen Dwyer

On Sat, Sep 8, 2012 at 7:22 PM, Romney, Jefferson S <address@hidden> wrote:
> I have had a similar problem that I think is the same cause. I take off in
> Auto2 with a catapult and it holds 15 degrees pitch until it gets to
> altitude. (that means it must not be the AHRS) then as soon as speed control
> kicks in when it moves to the standby block, it dives very violently it
> recovers after losing about 10-30 meters altitude, then flies normally. It
> must be in the airspeed or altitude loops because those are the only ones
> not active on takeoff when it works just fine. I haven't been able to figure
> this one out all year so if anyone can, it would be great.
>
> -Jefferson Romney
> ________________________________
> From: address@hidden
> address@hidden on behalf of
> Gautier Hattenberger address@hidden
> Sent: Saturday, September 08, 2012 3:16 PM
>
> To: address@hidden
> Subject: Re: [Paparazzi-devel] Strange behavior: pitch down when engaging
> AUTO2, only after launch.
>
> Hi,
>
> Maybe you can look at this
> http://lists.gnu.org/archive/html/paparazzi-devel/2012-06/msg00107.html
> It looks very similar.
>
> Gautier
>
> Le 08/09/2012 23:10, Mitchell SLOWER a écrit :
>
> I think you are right Eduardo.
> The attitude estimation when taking off with bungee might be not perfect, we
> should try the int_cmpl_quat_gravity_heuristic written by Felix.
>
> As I said before, I thought it was some I-term winding up, so I tried to
> decrease, even set to zero the two I-terms used in the control loops:
> v_ctl_auto_pitch_igain and v_ctl_auto_airspeed_igain. No improvement.
>
> Improvement happened when I commented out in the config file the auto pitch
> inner loop parameters: V_CTL_AUTO_PITCH_PGAIN et V_CTL_AUTO_PITCH_IGAIN. The
> plane was not diving dangerously anymore, but not getting altitude, just
> gliding on its track.
>
> Regards,
>
>
>
>
>
>
> 2012/9/8 Eduardo lavratti <address@hidden>
>>
>> Felix, the behavior that mitchel say is completely different than the
>> takeoff with bungee.
>>
>> BTW, some week ago i tested the auto takeoff using bungee and this
>> behavior not occur.
>> because of this i think its a integrator problem.
>>
>> i see int the code that some integrator are reset when manual are engaged.
>> I not remember if it is a throttle or climb integrator.
>>
>> ________________________________
>> Date: Sat, 8 Sep 2012 22:47:53 +0200
>> From: address@hidden
>>
>> To: address@hidden
>> Subject: Re: [Paparazzi-devel] Strange behavior: pitch down when engaging
>> AUTO2, only after launch.
>>
>> I'm pretty sure that the AHRS_GRAVITY_UPDATE_NORM_HEURISTIC in 4.0.1 has
>> almost no effect compared to not having it defined.
>> Whereas the improvements in my int_cmpl_quat_gravity_heuristic clearly
>> should help a lot (if the acceleration of the bungee takeoff is indeed the
>> problem).
>> At least in simulation I see a large (temporary) pitch error of up to
>> ~20deg before the improvements (of course depends on duration and
>> acceleration in bungee takeoff) before the improvements.
>>
>> On Sat, Sep 8, 2012 at 10:42 PM, Mitchell SLOWER
>> <address@hidden> wrote:
>>
>> Felix,
>>
>> I did a bungee test in AUTO1 with AHRS_GRAVITY_UPDATE_NORM_HEURISTIC
>> (4.0.1). It worked.
>>
>>
>> 2012/9/8 Felix Ruess <address@hidden>
>>
>> Hi,
>>
>> the pitching down after a bungee takeoff is definitely noticable, however
>> from what you describe I'm not sure if that is the only effect you are
>> seeing.
>>
>> But please note that AHRS_GRAVITY_UPDATE_NORM_HEURISTIC in v4.0 does not
>> really have a big effect.
>> As already mentioned previously in
>> http://lists.gnu.org/archive/html/paparazzi-devel/2012-08/msg00053.html
>> you can test the improved gravity norm heuristic from my
>> int_cmpl_quat_gravity_heuristic branch which is up-to-date with v4.0
>> otherwise.
>>
>> Would be great to get some feedback on this as I can't test this with a
>> real bungee takeoff myself.
>>
>> Cheers, Felix
>>
>>
>> On Sat, Sep 8, 2012 at 10:19 PM, Eduardo lavratti <address@hidden>
>> wrote:
>>
>> I have the same behavior.
>> i am using float_dcm and bungee but i think this is not due bungee.
>>
>> this behavior occur if i engage auto2 when pitching up.
>> If i pitch up, stabilize altitude and engage auto2 this behavior not
>> occur.
>> this seem that some I term are working but i not have time to search the
>> cause.
>>
>> i have to make this test.
>> takeoff in manual then engage auto2.
>> this will reset the integrator.
>>
>> regards
>>
>>
>> ________________________________
>> Date: Sat, 8 Sep 2012 21:57:52 +0200
>> From: address@hidden
>> To: address@hidden
>> Subject: Re: [Paparazzi-devel] Strange behavior: pitch down when engaging
>> AUTO2, only after launch.
>>
>>
>> Marc, Christophe: initially, I thought it could be an AHRS related
>> problem, but I'm think it's something else.
>> (I'm using int_cmpl_quat and the  AHRS_GRAVITY_UPDATE_NORM_HEURISTIC
>> flag).
>>
>> I think it's not related to AHRS because:
>> - I had a look at the estimator (theta), and pitch seems to be correct.
>> - If I lauch with the capatult, fly some time in manual, and engage AUTO2,
>> diving also happens.
>> - When I disable the airspeed from the airframe config file, everything
>> seems to work (I say "seems" because I did only one try that was
>> successful).
>>
>> Regards,
>> Mitchell
>>
>>
>> 2012/9/8 Christophe De Wagter <address@hidden>
>>
>> We have implemented the acceleration feedback in
>>
>>
>> https://github.com/tudelft/paparazzi/blob/tudelft4.0/sw/airborne/subsystems/ahrs/ahrs_float_dcm.c
>>
>> It has flown several times, including catapult launches but with the
>> complexity of all aspects involved (e.g. gps latency etc.) that is not a
>> guarantee. If you would be so kind to help test it it would be highly
>> appreciated.
>>
>> copy the file to your repo, add USE_AHRS_GPS_ACCELERATIONS to your
>> airframe (should pop a message during compile)
>>
>> -Christophe
>>
>>
>>
>> On Sat, Sep 8, 2012 at 8:58 PM, Marc Schwarzbach <address@hidden>
>> wrote:
>>
>> Hi Mitchell,
>>
>> your problem seems to be an AHRS calculation thing related with the high
>> acceleration at bungee take-off.
>> See the conversation one month ago: Subject: Re: [Paparazzi-devel]
>> int_cmpl_quat and bungee takeoff
>>
>> As a short note, I had a similar, but very light behaviour when hand
>> throwing my Easystar also with Lisa/M. It does a little pitch down before
>> starting to climb after the throw...
>>
>> Probably we should look into the ACC signals for fixed wing..
>>
>> Cheers
>>
>> Marc
>>
>>
>>
>> -------- Original-Nachricht --------
>> > Datum: Sat, 8 Sep 2012 20:37:18 +0200
>> > Von: Mitchell SLOWER <address@hidden>
>> > An: address@hidden
>> > Betreff: [Paparazzi-devel] Strange behavior: pitch down when engaging
>> > AUTO2,  only after launch.
>>
>>
>> > Dear all,
>> >
>> > I encounter a really strange behavior on a fixedwing.
>> > I had a look at the logs, made a lot of flights in order to find out
>> > what's
>> > wrong, but I really don't understand what's happening.
>> > So here is the situation:
>> >
>> > First, the setup:
>> > Lisa/M 2.0, PPZ Version: 4.0.1. I'm using an airspeed sensor,
>> > I'm launching the plane with a bungee, in manual mode.
>> > Before launch, current clock is set to circle over home, 150m AGL.
>> >
>> > What's happening:
>> > After launch, when I change to AUTO2 , the plane does not pitch up with
>> > motor on as expected in order to reach the desired altitude, but pitches
>> > down, gaining airspeed and loosing altitude (I checked that airspeed is
>> > near or over desired airspeed when I switch mode).
>> >
>> > As things get dangerous, I switch to MANUAL, get some altitude, engage
>> > AUTO2, and the same behavior occurs.
>> > Then, after a few tries like this, everything works ! And it works
>> > really
>> > fine, as I have a very good airspeed control and climb rate.
>> > After that, I can switch from MANUAL to AUTO2, and the plane behaves
>> > normally (get some altitude at the right airspeed and climbrate).
>> >
>> > I did a lot of tests (I initially thought of a I-term winding up), all
>> > were
>> > unsuccessful.
>> > The only clue I found: this problem might be related to the airspeed
>> > specific control loops, because when I disable the airspeed sensor from
>> > the
>> > airframe config file the plane seems to behave correctly (no pitch down
>> > when engaging auto2).
>> >
>> > Did anyone encounter the same behavior ?
>> > Do you have any idea about what could be happening ?
>> >
>> > Of course, I can provide further details, setup and logs.
>> >
>> > Regards,
>> > Mitchell
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>>
>> _______________________________________________ Paparazzi-devel mailing
>> list address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>>
>> _______________________________________________ Paparazzi-devel mailing
>> list address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>
>
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>
>
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>



reply via email to

[Prev in Thread] Current Thread [Next in Thread]