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Re: [Paparazzi-devel] Strange Servo Deflection Problem

From: Chris Wozny
Subject: Re: [Paparazzi-devel] Strange Servo Deflection Problem
Date: Mon, 30 Jan 2012 12:24:43 -0700

Helge and Andre,

The issue came from switching channels 1 and 2. For some reason I was
getting roll/pitch on my left stick and throttle/rudder on my right
stick so I changed channels 1 and 2 in the T7cap.xml file. I remember
reading somewhere before that channel 1 is only non-negative real
values, but I didn't think twice about it since I was getting a tiny
amount of deflection. I believe this small amount of control surface
deflection came from some residual noise in the system when the
control stick was fully pitched down. Switching channels 1 and 2
should resolve my issue then I must change the order of my servos
since left stick and right stick were originally reversed.

Thanks for all of your help!
University of Arizona MAV

On Mon, Jan 30, 2012 at 11:50 AM, Andre Devitt <address@hidden> wrote:
> 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
> element.
> 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
> servos.
> 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.
> Andre.
> 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

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