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Re: [Paparazzi-devel] Throttle dies in auto2

From: Pascal
Subject: Re: [Paparazzi-devel] Throttle dies in auto2
Date: Fri, 01 Sep 2006 23:22:06 +0200
User-agent: Debian Thunderbird 1.0.2 (X11/20050602)


I'm not sure to agree: nav_desired_gaz is used only in auto_pitch (CLIMB_PITCH_MODE) and fixed throttle mode (VERTICAL_MODE_AUTO_GAZ). The value of nav_desired_gaz is set in the same time than the mode (in the generated flight_plan.h file). So I don't see why it would help to set this variable somewhere else.
Could you provide the flight plan which is wrong ?


Roman Krashanitsa wrote:

I found the problem. It seems that nav_desired_gaz should be specified at least once 
taking into account logics of the flight plan. For example, if gaz is specified only once 
in the init block, the program may skip it due to (launch && z>ALT) already 
true and this variable will be left at 0, like in my case when it is being launched in 

As a solution for silly people like me, we could modify nav.c:359 from
uint16_t nav_desired_gaz;
uint16_t nav_desired_gaz=TRIM_UPPRZ((FAILSAFE_DEFAULT_GAZ)*MAX_PPRZ);

Or add
To nav_init(void)

Best regards,

-----Original Message-----
From: address@hidden [mailto:address@hidden
rg] On Behalf Of Pascal
Sent: Wednesday, August 30, 2006 2:56 PM
To: address@hidden
Subject: Re: [Paparazzi-devel] Throttle dies in auto2

Hi Roman, Hi Anton,

the default is "no slew" (pid.c:131, CLIMB_MAX_DIFF_GAZ=1).

What is expected (from what I reread in the code):
- MANUAL: no control on the throttle, you get what you set on the stick - AUTO1, AUTO2: slew is active: you cannot immediately go from throttle=0 to throttle=100%. The variation in time is limited by CLIMB_MAX_DIFF_GAZ

Before the switch
 - desired_gaz is set (main_ap.c:258)
 - pid_slew() is run (main_ap.c:462)
so the controller follows (with a delay) your manual throttle command (of course this desired_gaz value is unused by the fbw process in this mode) After the switch: desired_gaz smoothly evolves from the current value to the one computed by the controller (AUTO2) or set by the stick (AUTO1)

So I can't explain the problem you observe ... And I can't reproduce it with the simulator :-(

About the CLIMB_MODE_PITCH: desired_gaz is set to nav_desired_gaz which is set by the navigation task, i.e. the flight plan.

So we will have to boot a plane to figure out the problem. I think we almost never flew in MANUAL since the slew control was implemented ...

Last remark: do we really want the slew in AUTO1 ?


address@hidden wrote:

Ive seen this before.  What climb mode are you using?  If you arent
then Im pretty sure that part functions. However There is
a throttle
built in, Pascal would have to tell you whether its default
on or not,
as I
dont have code infront of me.


Quoting Roman Krashanitsa <address@hidden>:

Guys, I have this weird behavior while flying in manual/auto1 and then switching to auto2. First the throttle dies to 0, then slowly goes up to the required value. Im I doing something wrong?

I suspect that this is related to the initial value of nav_desired_gaz variable in nav.c when
All other cases use controlled_gaz.

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