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.
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@hiddenTo: 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
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
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