Re: [Paparazzi-devel] AP_MODE_FAILSAFE

[Gautier Hattenberger]

Hi,

On 02/11/2011 21:41, Felix Ruess wrote:
> Eric,
>
> > In my understand, the failsafe mode began active when we lost GPS or lost
> > Radio, in NAV-MODE
> read carefully, its when GPS _and_ radio is lost in nav that you go
> into the failsafe mode.
>
> This makes sort of sense, because if you still have RC you can still
> control the multicopter, if you don't have RC either.... well, you are
> screwed and want to go into the failsafe mode (i.e. set attitude to
> zero and slowly descend).
>
>
> Gautier,
> correct me if I'm wrong, but currently nothing is done if you just
> loose GPS in nav mode, right?
Correct
> Maybe we should go into some sort of (other) emergency mode in such a case?
For now, I was using the flight plan's exceptions to have this behavior, 
mainly during IMAV competition. Having this feature hard coded is 
possible but should be optional I think.
> > Also the horizontal control loops in hover and nav mode are slightly
> > different, so if you tune in hover, your flight in nav may not be as good.
> > So if your goal is to flight in nav mode, trim it in this mode. If you want
> > to fly manually and hover from time to time, trim using hover mode.
> This is very true, but not very nice...
> Assuming for now that you don't use the horizontal reference
> (GUIDANCE_H_USE_REF not defined and is hence zero) and you are within
> HOLD_DISTANCE, I would expect the same behavior from nav (with "stay"
> on a waypoint) as with AP_MODE_HOVER_*
Not a bad idea of course ;)
> What is the reason we have different scaling between these two modes??
> This doesn't really make sense to me.
> Any reason not to "fix" this and either change it in function
> guidance_h_hover_run (guidance_h.c 243) or guidance_h_nav_run
> (guidance_h.c 333)?
The first reason is that when I add the navigation to rotorcrafts, I 
didn't want to break the existing loops while testing some new ideas. 
The nav_err is one of them, but it is not that efficient in the end and 
I could never spend enough time on it.
Also I didn't like to have the scaling done some times on the gains, 
some times on the error, so I did it all on the errors, with a scaling 
as close as possible but not exactly the same (I don't remember all the 
reasons).
> What I also just noticed in guidance_h_nav_run:
> Shouldn't we reset guidance_h_nav_err to zero if we are within
> HOLD_DISTANCE? Otherwise we will continually use an old tracking
> nav_err if we get closer than HOLD_DISTANCE to the waypoint.
My mistake. As I said, this part is not finished, and I'm not using it 
myself for now

Gautier

> Cheers, Felix
>
> On Wed, Nov 2, 2011 at 5:53 PM, Eric BAHIER<address@hidden>  wrote:
> > hi,
> >
> > I will move to NAV, and I'll define only one stand-by point.... In this case
> > th AP_MODE_Failsafe will be applicable, and efficient..
> > Thanks,
> >
> > Eric
> >
> > Le 02/11/2011 17:45, Gautier Hattenberger a écrit :
> >
> > Hi,
> >
> > There is no "almost" nav mode. Being in nav mode means that you are using
> > the flight plans instructions to fly. If you really want to only hover while
> > being in this mode, you can just make a flight plan that waits for the gps
> > and then saty at a given waypoint.
> > Also the horizontal control loops in hover and nav mode are slightly
> > different, so if you tune in hover, your flight in nav may not be as good.
> > So if your goal is to flight in nav mode, trim it in this mode. If you want
> > to fly manually and hover from time to time, trim using hover mode.
> >
> > Gautier
> >
> > On 02/11/2011 16:53, Eric BAHIER wrote:
> >
> > hi felix,
> >
> > In my understand, the failsafe mode began active when we lost GPS or lost
> > Radio, in NAV-MODE
> >
> > I read it on
> > :"http://paparazzi.enac.fr/wiki/Rotorcraft_Configuration#Autopilot_modes";,
> > your link :
> > AP_MODE_FAILSAFE
> >
> > This is a failsafe mode that gets triggered if:
> >
> > RC signal is lost (and you are not in KILL or NAV mode)
> > GPS and RC is lost in NAV mode
> >
> > I can accept,  AP_MODE_HOVER_DIRECT and AP_MODE_HOVER_Z_HOLD are not realy
> > in NAV mode, but "almost nav mode".
> >
> > For my test I want first to have AP_MODE_HOVER_Z_HOLD full opperational up
> > to  ????xx km/h wind, and move to NAV when the stationair(GPS) fly is done.
> > how to, to triggered the AP_MODE_FAILSAFE , for my understand, this setup is
> > indépendant from manual/auto1/auto2....I missuterstand?
> >
> >
> > regards,
> >
> > Eric
> >
> >
> >
> > The autopilot will level the rotorcraft out (setpoints to zero pitch and
> > roll angles) and descend at 0.5m/s downwards.
> >
> > Le 02/11/2011 14:29, Eric BAHIER a écrit :
> >
> > Hi,
> >
> > I woulds like to use  "AP_MODE_FAILSAFE ".
> >
> > Currently I use :
> >
> > <section name="MODE">
> >    <define name="MANUAL" value="AP_MODE_ATTITUDE_DIRECT" />
> >    <define name="AUTO1" value="AP_MODE_HOVER_DIRECT" />
> >    <define name="AUTO2" value="AP_MODE_HOVER_Z_HOLD" />
> > </section>
> >
> > I would like to have "AP_MODE_FAILSAFE" active in HOVERs mode,   is it
> > possible?
> >
> > I probably lost the GPS some time in HOVER.... and the quad go away...where
> > it can....  If is stay and land it could be nice for debuging.
> >
> >
> > Where, how to... I will proced to use "AP_MODE_FAILSAFE"....
> >
> > Thanks,
> >
> > eric
> >
> >
> >
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> >
> >
> >
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> >
> > Eric BAHIER
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> >
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> >
> > Eric BAHIER
> > 15 chemin neuf
> > 34 980 Montferrier sur LEZ
> > France
> >
> > Tel : 33 4 67 59 92 53
> > Fax : 33 9 59 15 92 53
> > ************************************
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