Re: [Paparazzi-devel] Strange throttle behavior

[Eduardo lavratti]

Some news Simon ?

> Date: Tue, 20 Dec 2011 13:33:19 +0100
> From: address@hidden
> To: address@hidden
> Subject: Re: [Paparazzi-devel] Strange throttle behavior
>
> If you mean the bound_commands_step that was added by Piotr in May,
> but unless SUPERVISION_MAX_NEGATIVE_MOTOR_STEP or
> SUPERVISION_MAX_POSITIVE_MOTOR_STEP is explicitly defined in the
> airframe file that is not used...
>
> On Tue, Dec 20, 2011 at 1:20 PM, antoine drouin <address@hidden> wrote:
> > I just looked at the file and noticed that someone added a sort of low
> > pass filter in there. It would probably be nicer to handle the
> > dynamics of the commands in the stabilization layer.
> >
> > On Tue, Dec 20, 2011 at 1:14 PM, antoine drouin <address@hidden> wrote:
> >> take a look at
> >>  paparazzi/sw/airborne/firmwares/rotorcraft/actuators/supervision.c
> >> This was my first attempt at handling actuators saturation issues. You
> >> are correct that the attitude stabilization is given priority over
> >> vertical guidance. It's based on the assumption that the angular
> >> dynamic is faster than the vertical one.
> >>
> >> Poine
> >>
> >> On Tue, Dec 20, 2011 at 1:06 PM, Simon Wilks <address@hidden> wrote:
> >>> Hi Felix,
> >>>
> >>> On Tue, Dec 20, 2011 at 2:09 AM, Felix Ruess <address@hidden> wrote:
> >>>>
> >>>> Hi Simon,
> >>>>
> >>>> yes, when it's armed the motors will idle at low rpms with zero
> >>>> throttle on the RC.
> >>>> From your config it looks like you were testing in attitude_direct
> >>>> mode?
> >>>
> >>> Correct.
> >>>
> >>>>
> >>>> In that case the guidance_v p gain does not play any roll at
> >>>> all, since throttle is directly controlled via RC.
> >>>
> >>>
> >>> I see. I will give it a try seeing Eduardo seems to think it helps. It will
> >>> at least not hurt if it isn't used.
> >>>>
> >>>>
> >>>> I haven't heard or experienced your problem with throttle lag
> >>>> before... maybe it's a problem with 8 motors and i2c? That is a shot
> >>>> in the dark, but you could test with increasing the i2c queue to more
> >>>> than 10 (that's just what others reported on the mailing list for 8
> >>>> motors).
> >>>>
> >>>>
> >>>> When you hold the quadcopter with zero throttle and tilt it a bit it
> >>>> should immediately try to compensate for that.... sluggish response to
> >>>> that might indicated an i2c queue problem...
> >>>
> >>>
> >>> When I tip the copter in any direction it seems to respond correctly and
> >>> very quickly. I will probably give the i2c queue adjustment a try as well.
> >>>>
> >>>>
> >>>> With respect to switching off attitude control at zero RC throttle
> >>>> input: I didn't quite get why you'd want to switch that off and IMHO
> >>>> opinion that is not such a good idea (at least I can't think of a
> >>>> reason right now).
> >>>> E.g. when you want the copter to fall really quickly and you take the
> >>>> throttle to zero, you really don't want stabilization completely
> >>>> switched off.
> >>>
> >>>
> >>> OK, I agree that it probably isn't a good idea then :) Didn't think of that.
> >>>
> >>> The throttle issue only happens when the copter is in flight and I have
> >>> never noticed something like this when throttling up (and then down) while
> >>> remaining on the ground. I wonder if this is an effect of it overdoing the
> >>> attitude control as it should be sinking and it just puts too much power
> >>> into the stabilization attempts, at least for an octocopter?
> >>>
> >>> Thanks,
> >>>
> >>> Simon
> >>>
> >>>>
> >>>> If one wanted to do that at all, one could think about using something
> >>>> like the autopilot_in_flight state to check if the copter is not in
> >>>> flight AND the rc throttle at zero to switch it off... but that would
> >>>> need some modifications for takeoff.
> >>>>
> >>>> Cheers, Felix
> >>>>
> >>>> On Mon, Dec 19, 2011 at 7:42 PM, Simon Wilks <address@hidden> wrote:
> >>>> > On Mon, Dec 19, 2011 at 6:23 PM, Eduardo lavratti
> >>>> > <address@hidden>
> >>>> > wrote:
> >>>> >>
> >>>> >> As i tell you ... i have the same behavior when i using a HIGH valeu on
> >>>> >> guidance_V P parameter.
> >>>> >
> >>>> > OK, got it.
> >>>> >
> >>>> >
> >>>> >>
> >>>> >>
> >>>> >> This is the first think that i will modify in PPZ software.
> >>>> >> When the throttle is around 0 the ATTITUDE control stop control the
> >>>> >> motors.
> >>>> >
> >>>> > That would be great. This is pretty nasty (and extremely surprising)
> >>>> > behavior.
> >>>> >
> >>>> > Thanks
> >>>> >
> >>>> > Simon
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> ________________________________
> >>>> >> Date: Mon, 19 Dec 2011 09:56:34 +0100
> >>>> >> From: address@hidden
> >>>> >> To: address@hidden
> >>>> >> Subject: Re: [Paparazzi-devel] Strange throttle behavior
> >>>> >>
> >>>> >>
> >>>> >> I just replayed the logs and the GCS shows the throttle input going to
> >>>> >> 0%
> >>>> >> after about 3 secs but the octocopter was clearly still flying for
> >>>> >> another
> >>>> >> 3-4 secs after this I till I hit the kill switch.
> >>>> >>
> >>>> >> On Sun, Dec 18, 2011 at 10:13 PM, Simon Wilks <address@hidden>
> >>>> >> wrote:
> >>>> >>
> >>>> >> On Sun, Dec 18, 2011 at 10:06 PM, Hector Garcia de Marina
> >>>> >> <address@hidden> wrote:
> >>>> >>
> >>>> >> Yeah,
> >>>> >>
> >>>> >> regarding the safety, I agree with Eduardo, next time DO NOT run next
> >>>> >> to
> >>>> >> the copter if you have lost its control until it completely
> >>>> >> is switched off.
> >>>> >>
> >>>> >>
> >>>> >> Yes you are right. I should keep clear till it has settled.
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> Cheers
> >>>> >>
> >>>> >>
> >>>> >> On Sun, Dec 18, 2011 at 9:31 PM, Eduardo lavratti
> >>>> >> <address@hidden>
> >>>> >> wrote:
> >>>> >>
> >>>> >> Hey man ... take care with your tests !
> >>>> >> This props and motors are very POWER and DANGEROUS !
> >>>> >> Take a look at this pictures
> >>>> >> http://brquad.blogspot.com/2011/04/little-acident-with-my-big-hexa.html
> >>>> >> This accident occurred when i make some tests with my big hexa whit
> >>>> >> same
> >>>> >> motors and props.
> >>>> >> Never make this tests with children arround.
> >>>> >> Well, for the JUMP problem reduce the "guidance_V / hover_KP" and make
> >>>> >> a
> >>>> >> test.
> >>>> >>
> >>>> >> Make the same for wooble. Reduce the P & D GAIN parameter for Theta and
> >>>> >> Phi . You see this values in STABILIZATION_ATTITUDE section.
> >>>> >> Reduce P for 300 and make a test.
> >>>> >>
> >>>> >> Stay sure that your props are very well balanced or your lisa board
> >>>> >> have a
> >>>> >> good vibration isolation.
> >>>> >>
> >>>> >> When i make my first fly using lisa/m i have similar attitude on me
> >>>> >> small
> >>>> >> octo (5"props) and on my quad (8" props)
> >>>> >> after i balance the props and make a good vibration isolation all
> >>>> >> problems
> >>>> >> are solved.
> >>>> >>
> >>>> >> Regards and sorry for my poor english.
> >>>> >>
> >>>> >> Eduardo Lavratti
> >>>> >> Brasilian UAV developer.
> >>>> >>
> >>>> >>
> >>>> >> ________________________________
> >>>> >> Date: Sun, 18 Dec 2011 20:38:21 +0100
> >>>> >> From: address@hidden
> >>>> >> To: address@hidden
> >>>> >> Subject: [Paparazzi-devel] Strange throttle behavior
> >>>> >>
> >>>> >>
> >>>> >> Hi
> >>>> >>
> >>>> >> I have been noticing what seemed like a lag in throttle control though
> >>>> >> I
> >>>> >> wasn't 100% sure till my first test flight today (octocopter, lisa/l,
> >>>> >> spektrum satellite receiver). While on the ground I don't seem to
> >>>> >> notice
> >>>> >> this effect but when holding it above my head or lifting off strange
> >>>> >> things
> >>>> >> start to happen.
> >>>> >>
> >>>> >> When holding it above my head changing the throttle on the sender seems
> >>>> >> to
> >>>> >> take a second or two till it happens on the copter. I have also noticed
> >>>> >> what
> >>>> >> seems to be a general increase in throttle all of sudden, not just to
> >>>> >> correct attitude but like a it wants to pull up and away.
> >>>> >>
> >>>> >> When I tried the first flight today I got a bit of a shock when I
> >>>> >> wanted
> >>>> >> to just lift off a bit then set down only to discover it did not want
> >>>> >> to
> >>>> >> respond to the fact that I had returned the throttle back to zero and
> >>>> >> skipped off across the garden. In the end I had to flick the kill
> >>>> >> switch.
> >>>> >> Pretty funny after the event. I have a video if you want a laugh here.
> >>>> >>
> >>>> >> You will see the props rotating at minimum speed (zero throttle on the
> >>>> >> sender) after arming. I assume this is correct? One of the props isn't
> >>>> >> rotating properly and I suspect it might have a problem and need
> >>>> >> swapping
> >>>> >> with a spare (it has a bit more resistance to the hand when rotating
> >>>> >> than
> >>>> >> the others) but I thought it might be OK to try a small hover anyway.
> >>>> >>
> >>>> >> Any ideas what causes this kind of throttle behavior? Pitch and roll
> >>>> >> seem
> >>>> >> pretty responsive. Here is the aircraft config.
> >>>> >>
> >>>> >> Thanks
> >>>> >>
> >>>> >> Simon
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> _______________________________________________ Paparazzi-devel mailing
> >>>> >> list address@hidden
> >>>> >> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
> >>>> >>
> >>>> >> _______________________________________________
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> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> --
> >>>> >> Héctor
> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >> _______________________________________________
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> >>>> >>
> >>>> >>
> >>>> >>
> >>>> >>
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> >>>> >
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