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Re: [Paparazzi-devel] Strange Servo Deflection Problem

From: Andre Devitt
Subject: Re: [Paparazzi-devel] Strange Servo Deflection Problem
Date: Mon, 30 Jan 2012 13:50:19 -0500

Can you try running the autopilot (prop off) on the plane and looking
at the following values.

First, in the GCS go to the settings tab and find the TELE_FBW_MODE
radio button. It will probably be o  0, change it to 1 and then open
up the Messages window. (In paparazzi center, tools->messages)

Next, in the GCS verify that you are in manual mode. (bottom left of
the GCS, should say
 Manual, Auto1 or Auto2, or Home).

Now open the messages window and look at the Commands window. This is
an array of values range [-9600 to 9600]. The order should be
throttle, roll, pitch, yaw. Verify with your tx sticks changes these
values in the proper direction and go to (at least close to) full
travel. That is, full pitch should read +9600 in the third element of
array, full negative pitch should read about -9600  in that same

Once you've verified that all commands are correct, you can check the
actuators message. These are the pulse widths being sent to the servos
(approx 1000-2000ms for all your servos from looking at airframe,
tends to be the standard). Verify that these actuator values are
changing as you would expect them to and see if they hit any limits
when going to positive pitch.

These steps should help you isolate whether your problem is in the
intermediate commands paparazzi generates or the commands sent to

Another thing to check is the RC values (actually should probably
check this first). After setting the TELETRY_FBW_MODE to 1 as I said
at the top of the post you should  see a message called "RC". This
message has the RC values coming from the TX to paparazzi. Take a look
at them and make sure they make sense in terms of sign and magnitude
in the same way as the commands section.


On Sat, Jan 28, 2012 at 3:12 PM, Helge Walle <address@hidden> wrote:
> Hi,
> It seems you have the opposite order on ch1 and ch2 compared to my Futaba
> 10CG in 7ch mode. could that be the problem?
> This is my radio file:
> <!DOCTYPE radio SYSTEM "radio.dtd">
> <radio name="T10CG7" data_min="900" data_max="2100" sync_min="5000"
> sync_max="15000" pulse_type="POSITIVE">
>   <channel ctl="right_stick_horiz" function="ROLL" min="1936" neutral="1525"
> max="1110" average="0"/>
>   <channel ctl="right_stick_vert" function="PITCH" min="1107" neutral="1520"
> max="1933" average="0"/>
>   <channel ctl="left_stick_vert" function="THROTTLE" min="1107"
> neutral="1107" max="1933" average="0"/>
>   <channel ctl="left_stick_horiz" function="YAW" min="1929" neutral="1516"
> max="1104" average="0"/>
>   <channel ctl="switch_G" function="CALIB" min="963" neutral="963"
> max="2069" average="10"/>
>   <channel ctl="VRA" function="GAIN1" min="964" neutral="1489" max="2070"
> average="0"/>
>   <channel ctl="switch_C" function="MODE" min="2072" neutral="1511"
> max="967" average="10"/>
> </radio>
> Helge.
> 2012/1/28 Chris Wozny <address@hidden>
>> Andre,
>> That is correct, I'm building against paparazzi dev branch. I believe
>> the radio channels are correct because the sticks all correspond to
>> what I want them to do. Left stick vertical is throttle while
>> horizontal is rudder, right stick vertical is pitch while horizontal
>> is roll (the only thing that is off is that pitch down only moves the
>> control surfaces down about 5% of the control surface movement when
>> pitching up.) The only thing I don't know about is any of the
>> switches, they don't seem to correspond to anything I've set in the
>> T7cap configuration since currently switch B controls the APs mode.
>> You are right about the autopilot section looking funky, our aircraft
>> is a VTOL fixed wing so for AUTO1 we'd like to fly it with a certain
>> altitude or just hover at a certain attitude. We haven't actually been
>> able to test those AP modes since we're still trying to get it to fly
>> in manual. Any thoughts or comments on the servo deflection, or
>> anything else for that matter would be appreciated!
>> Best,
>> Chris
>> --
>> University of Arizona MAV
>> On Fri, Jan 27, 2012 at 8:10 PM, Andre Devitt <address@hidden>
>> wrote:
>> > Have you looked at the commands message in the messages window?
>> >
>> > Maybe radio channels are configured incorrectly. I think throttle is
>> > clipped
>> > to positive only, and if throttle radio channel was being interpreted as
>> > pitch might see that behavior.
>> >
>> > Some sections of your airframe file are also only relevant for
>> > rotorcraft
>> > firmware, not sure what you used as template. The AP mode section stuck
>> > out.
>> >
>> > This airftame file is building against current github paparazzi-devel
>> > head,
>> > correct?
>> >
>> > On Jan 27, 2012 7:48 PM, "Chris Wozny" <address@hidden> wrote:
>> >>
>> >> All,
>> >>
>> >> For some reason I have good range on my deflection for my servos when
>> >> I roll. When I pitch up, the deflection is also good and just how I
>> >> want it. However, when I pitch down, my servos barely move from
>> >> neutral. Has anyone run into this situation before? It's got to be
>> >> some sort of pitch gain somewhere, but I'm flying in MANUAL. I've
>> >> linked copies of my airframe and my radio file here:
>> >>
>> >>
>> >>
>> >>
>> >> Best,
>> >> Chris
>> >> --
>> >> University of Arizona MAV
>> >>
>> >> _______________________________________________
>> >> Paparazzi-devel mailing list
>> >> address@hidden
>> >>
>> --
>> Chris Wozny
>> ASUA Safe Ride
>> Administrative Director
>> Email: address@hidden
>> Office: 520-621-7233
>> Cell: 617-921-5679
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
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