[Paparazzi-devel] Paparazzi-devel Digest, Vol 100, Issue 28

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Today's Topics:

   1. Re: AHRS_H from GPS fix (Sergei Krukovski)
   2. Re: AHRS_H from GPS fix (Felix Ruess)
   3. Re: With or without airspeed indicator (eagle     tree pitot)
      (Jorge Pantoja)
   4. Roll and Yaw Control (Jorge Pantoja)


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Message: 1
Date: Fri, 13 Jul 2012 18:36:48 +0100 (BST)
From: Sergei Krukovski <address@hidden>
To: "address@hidden" <address@hidden>
Subject: Re: [Paparazzi-devel] AHRS_H from GPS fix
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

I've done a module, based on WMM2010 modell and it seems to work.

Regards,
Sergey
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Message: 2
Date: Fri, 13 Jul 2012 20:57:15 +0200
From: Felix Ruess <address@hidden>
To: Sergei Krukovski <address@hidden>, address@hidden
Subject: Re: [Paparazzi-devel] AHRS_H from GPS fix
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="utf-8"

Hi Sergey,

that is one of the many things is on the wish-list, but other stuff has
higher priority.
Since you already implemented it, would you mind making a pull request or
post some patches here?

Cheers, Felix

On Fri, Jul 13, 2012 at 7:36 PM, Sergei Krukovski <address@hidden> wrote:

> I've done a module, based on WMM2010 modell and it seems to work.
>
> Regards,
> Sergey
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>
>
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Message: 3
Date: Fri, 13 Jul 2012 17:03:10 -0400
From: Jorge Pantoja <address@hidden>
To: address@hidden
Subject: Re: [Paparazzi-devel] With or without airspeed indicator
        (eagle  tree pitot)
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="iso-8859-1"

Hello H?ctor and Reto,

Thank you very much for your responses. We will go flight testing without
the airspeed sensor and see how the airplane behaves ;).

Best Regards,
Jorge

On Thu, Jul 12, 2012 at 3:36 AM, Hector Garcia de Marina
<address@hidden>wrote:

> Hi Jorge,
>
> airspeed is useful for stability (if you work respecting to the stability
> axes with AoA and AoS angles instead of body frame/navigation frame). If
> you have characterized your plane in a wind tunnel, and you know
> the optimum AoA and Airspeed for ration Lift/Drag (you know CL, CD and so
> on), or for preventing stall, etc, then is useful the airspeed (remember
> that you flying respecting the air axes, and not the ground axes).
>
> As far as I know, paparazzi (so far), does not cover this kind of stuff
> (yet!). The main issue is to obtain a reliable, cheap and small sensors for
> AoA, AoS angles.
>
> H?ctor
>
>
> On Thu, Jul 12, 2012 at 9:30 AM, Reto B?ttner <address@hidden>wrote:
>
>> Hi Jorge
>>
>> I do not recommend an airspeed sensor. To my experience it is not worth
>> the effort, cost and complexity.
>>
>> I experienced problems integrating the eagletree airspeed sensor on my
>> eHawk. Connecting it to paparazzi via i2c and integrating it in the
>> software worked fine as described on the wiki. But the sensor measurement
>> was to inaccurate. I didn't find out why (pitot tube or pressure sensor). I
>> didn't get better flight results than using standard paparazzi GPS control.
>> Therefore I am not using the airspeed sensor anymore. I get perfect flight
>> results in precision and reliabiliy without an airspeed sensor.
>>
>> The chance of saving an UAV thanks to an airspeed sensor when GPS fails
>> is minimal. Your IMU will start to drift whithout GPS calibration and
>> attitude control will fail. You could use IR sensors instead of an IMU as
>> they work perfectly without GPS. Or you could use a sophisticated IMU that
>> doesn't require GPS calibration. Still the airspeed sensor is no real added
>> value. First you can control speed fine using throttle and pitch angle
>> without having an airspeed sensor. Second even if you can control attitude
>> and speed, you are likely to lose your UAV without GPS as you will not find
>> home.
>>
>> For reliability you better consider FPV as fall back. That works no
>> matter which part of the autopilot fails.
>>
>> Even better go for simplicity. To my experience simplicity is the most
>> effective way to reliabilty. Adding more systems and redundancy you
>> introduce more failure modes and interactions. It requires great effort to
>> really enhance reliabilty by adding more systems. It is more effective to
>> invest that effort in robust design (e.g. preventing interference),
>> testing, maintenance, operation procedures and training.
>>
>> Happy landings,
>> Reto
>>
>>
>> 2012/7/12 Jorge Pantoja <address@hidden>
>>
>>> Hi Christophe,
>>>
>>> Thank you for your answer. So, should I connect the pitot to have it in
>>> case of GPS failure? Is there an additional programing that needs to be
>>> done?
>>>
>>> Regards,
>>> Jorge
>>>
>>> On Wed, Jul 11, 2012 at 1:43 PM, Christophe De Wagter <
>>> address@hidden> wrote:
>>>
>>>> Paparazzi CHIMU code uses GPS to get the speed. This is in theory
>>>> more accurate than airspeed. You would only want to feedback airspeed when
>>>> the GPS is failing
>>>>
>>>> -Christophe
>>>>
>>>>
>>>>
>>>> On Wed, Jul 11, 2012 at 6:35 PM, Jorge Pantoja <
>>>> address@hidden> wrote:
>>>>
>>>>> Hi everyone,
>>>>>
>>>>> I am using a Yapa2 + CHIMU + Ublox GPS LEA 5H + 900 MHz Xbees. All the
>>>>> hardware is integrated properly, but I have a question: Would you 
>>>>> recommend
>>>>> integrating the Eagle Tree Airspeed sensor as well?
>>>>>
>>>>> According to the CHIMU manual we need an extra airspeed sensor to
>>>>> correct the measurements given to the autopilot.
>>>>>
>>>>> Best Regards,
>>>>> --
>>>>> *Jorge Pantoja*
>>>>> *Program Manager/Liaison*
>>>>> *Phone:* +593-96160076
>>>>> *e-mail:* address@hidden
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> Paparazzi-devel mailing list
>>>>> address@hidden
>>>>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>>
>>>>>
>>>>
>>>> _______________________________________________
>>>> Paparazzi-devel mailing list
>>>> address@hidden
>>>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>>
>>>>
>>>
>>>
>>> --
>>> *Jorge Pantoja*
>>> *Program Manager/Liaison*
>>> *Phone:* +593-96160076
>>> *e-mail:* address@hidden
>>>
>>>
>>>
>>> _______________________________________________
>>> Paparazzi-devel mailing list
>>> address@hidden
>>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>>
>>>
>>
>> _______________________________________________
>> Paparazzi-devel mailing list
>> address@hidden
>> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>>
>>
>
>
> --
> H?ctor
>
>
>
> _______________________________________________
> Paparazzi-devel mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/paparazzi-devel
>
>


-- 
*Jorge Pantoja*
*Program Manager/Liaison*
*Phone:* +593-96160076
*e-mail:* address@hidden
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Message: 4
Date: Fri, 13 Jul 2012 17:31:08 -0400
From: Jorge Pantoja <address@hidden>
To: address@hidden
Subject: [Paparazzi-devel] Roll and Yaw Control
Message-ID:
        <address@hidden>
Content-Type: text/plain; charset="iso-8859-1"

Hi everyone,

We are using the following hardware configuration:

Yapa2 + CHIMU + Ublox GPS + 900 MHz Xbees

After mounting the autopilot to the airplane and connected everything we
tested the equipment and we noticed that when we "YAWed"  the airplane we
had no response from the Rudder. On the other hand, when we "Pitched and
Rolled" the airplane we could see that there was a response from the
ailerons and elevator. Is this correct? Should or shouldn't we expect a
response from the Rudder?

About Roll control, I noticed that in our airframe file we have 2 servos
controlling our airplane's roll, but our aircraft only has 1 channel moving
the ailerons. Can I leave it this way? Or should I change the airframe file
and erase the channel moving the extra aileron?

Here is the airframe file we are using:

<airframe name="Piquero">


  <servos>
    <servo name="THROTTLE" no="0" min="1000" neutral="1000" max="2000"/>
    <servo name="AILERON_LEFT" no="3" min="1000" neutral="1500"
max="2000"/>
    <servo name="AILERON_RIGHT" no="1" min="2000" neutral="1500"
max="1000"/>
    <servo name="ELEVATOR" no="2" min="2000" neutral="1500" max="1000"/>
    <servo name="RUDDER" no="6" min="1100" neutral="1500" max="1900"/>
  </servos>

  <commands>
    <axis name="THROTTLE" failsafe_value="0"/>
    <axis name="ROLL" failsafe_value="0"/>
    <axis name="PITCH" failsafe_value="0"/>
    <axis name="YAW" failsafe_value="0"/> <!-- both elerons up as butterfly
brake ? -->
  </commands>

  <rc_commands>
    <set command="THROTTLE" value="@THROTTLE"/>
    <set command="ROLL" value="@ROLL"/>
    <set command="PITCH" value="@PITCH"/>
    <set command="YAW" value="@YAW"/>
  </rc_commands>

  <section name="SERVO_MIXER_GAINS">
    <define name="AILERON_RATE_UP" value="0.50f"/>
    <define name="AILERON_RATE_DOWN" value="0.25f"/>

    <define name="AILERON_RATE_UP_BRAKE" value="0.5f"/>
    <define name="AILERON_RATE_DOWN_BRAKE" value="0.9f"/>

    <define name="PITCH_GAIN" value="0.9f"/>

    <define name="YAW_THRUST" value="0.0f"/>
    <define name="BRAKE_AILEVON" value="-0.68f"/>
    <define name="BRAKE_PITCH" value="0.0f"/>
    <define name="MAX_BRAKE_RATE" value="150"/>

    <define name="LIMIT(X,XL,XH)" value="( ((X)>(XH)) ? (XH) : ( ((X)>(XL))
? (X) : (XL) ) )"/>
  </section>

  <command_laws>
    <!-- Differential Aileron Depending on Brake Value -->
    <set servo="AILERON_LEFT" value="@ROLL"/>
    <set servo="AILERON_RIGHT" value="@ROLL"/>

    <!-- Differential Thurst -->
    <set servo="THROTTLE" value="@THROTTLE"/>

    <!-- Pitch with Brake-Trim Function -->
    <set servo="ELEVATOR" value="@PITCH"/>
    <set servo="RUDDER" value="@YAW"/>
  </command_laws>

  <section name="INS" prefix="INS_">
    <define name="ROLL_NEUTRAL_DEFAULT" value="0" unit="deg"/>
    <define name="PITCH_NEUTRAL_DEFAULT" value="0" unit="deg"/>
  </section>

  <section name="AUTO1" prefix="AUTO1_">
    <define name="MAX_ROLL" value="0.7"/>
    <define name="MAX_PITCH" value="0.7"/>
  </section>

  <section name="BAT">
    <define name="MilliAmpereOfAdc(adc)" value="((adc) - 505) * 124.0f"/>

    <define name="LOW_BAT_LEVEL" value="10.5" unit="V"/>
    <define name="CRITIC_BAT_LEVEL" value="10" unit="V"/>
    <define name="CATASTROPHIC_BAT_LEVEL" value="9.1" unit="V"/>
  </section>

  <section name="MISC">
    <define name="NOMINAL_AIRSPEED" value="13." unit="m/s"/>
    <define name="CARROT" value="5." unit="s"/>
    <define name="CONTROL_RATE" value="60" unit="Hz"/>
    <define name="XBEE_INIT" value="&quot;ATPL2\rATRN5\rATTT80\r&quot;"/>
<!-- <define name="NO_XBEE_API_INIT" value="TRUE"/> -->
    <define name="ALT_KALMAN_ENABLED" value="TRUE"/>
    <define name="DEFAULT_CIRCLE_RADIUS" value="80."/>

    <define name="GLIDE_AIRSPEED" value="10"/>
    <define name="GLIDE_VSPEED" value="3."/>
    <define name="GLIDE_PITCH" value="45" unit="deg"/>
  </section>

  <section name="VERTICAL CONTROL" prefix="V_CTL_">
    <define name="POWER_CTL_BAT_NOMINAL" value="11.1" unit="volt"/>
    <!-- outer loop proportional gain -->
    <define name="ALTITUDE_PGAIN" value="-0.03"/>
<!-- -0.03"/> -->
    <!-- outer loop saturation -->
    <define name="ALTITUDE_MAX_CLIMB" value="2."/>

    <!-- auto throttle inner loop -->
    <define name="AUTO_THROTTLE_NOMINAL_CRUISE_THROTTLE" value="0.32"/>
    <define name="AUTO_THROTTLE_MIN_CRUISE_THROTTLE" value="0.25"/>
    <define name="AUTO_THROTTLE_MAX_CRUISE_THROTTLE" value="0.65"/>
    <define name="AUTO_THROTTLE_LOITER_TRIM" value="1500"/>
    <define name="AUTO_THROTTLE_DASH_TRIM" value="-4000"/>
    <define name="AUTO_THROTTLE_CLIMB_THROTTLE_INCREMENT" value="0.15"
unit="%/(m/s)"/>
    <define name="AUTO_THROTTLE_PGAIN" value="-0.01"/>
    <define name="AUTO_THROTTLE_IGAIN" value="0.1"/>
    <define name="AUTO_THROTTLE_PITCH_OF_VZ_PGAIN" value="0.05"/>

    <define name="THROTTLE_SLEW_LIMITER" value="2" unit="s"/>
  </section>

  <section name="HORIZONTAL CONTROL" prefix="H_CTL_">
    <define name="COURSE_PGAIN" value="-1.20000004768"/>
    <define name="COURSE_DGAIN" value="0.3"/>
    <define name="COURSE_PRE_BANK_CORRECTION" value="0.2"/>

    <define name="ROLL_MAX_SETPOINT" value="0.9" unit="radians"/>
    <define name="PITCH_MAX_SETPOINT" value="0.5" unit="radians"/>
    <define name="PITCH_MIN_SETPOINT" value="-0.5" unit="radians"/>

    <define name="PITCH_PGAIN" value="-12000."/>
    <define name="PITCH_DGAIN" value="0"/>

    <define name="ELEVATOR_OF_ROLL" value="1000."/>

    <define name="ROLL_ATTITUDE_GAIN" value="-11500"/>
    <define name="ROLL_RATE_GAIN" value="-600."/>
  </section>

  <section name="AGGRESSIVE" prefix="AGR_">
    <define name="BLEND_START" value="20"/><!-- Altitude Error to Initiate
Aggressive Climb CANNOT BE ZERO!!-->
    <define name="BLEND_END" value="10"/><!-- Altitude Error to Blend
Aggressive to Regular Climb Modes CANNOT BE ZERO!!-->
    <define name="CLIMB_THROTTLE" value="1.00"/><!-- Gaz for Aggressive
Climb -->
    <define name="CLIMB_PITCH" value="0.3"/><!-- Pitch for Aggressive Climb
-->
    <define name="DESCENT_THROTTLE" value="0.1"/><!-- Gaz for Aggressive
Decent -->
    <define name="DESCENT_PITCH" value="-0.25"/><!-- Pitch for Aggressive
Decent -->
    <define name="CLIMB_NAV_RATIO" value="0.8"/><!-- Percent Navigation for
Altitude Error Equal to Start Altitude -->
    <define name="DESCENT_NAV_RATIO" value="1.0"/>
  </section>

  <section name="FAILSAFE" prefix="FAILSAFE_">
    <define name="DEFAULT_THROTTLE" value="0.35" unit="%"/>
    <define name="DEFAULT_ROLL" value="0.17" unit="rad"/>
    <define name="DEFAULT_PITCH" value="0.08" unit="rad"/>

    <define name="HOME_RADIUS" value="DEFAULT_CIRCLE_RADIUS" unit="m"/>
    <define name="KILL_MODE_DISTANCE" value="(MAX_DIST_FROM_HOME*1.5)"/>
    <define name="DELAY_WITHOUT_GPS" value="3" unit="s"/>
  </section>

  <section name="DIGITAL_CAMERA" prefix="DC_">
    <define name="AUTOSHOOT_QUARTERSEC_PERIOD" value="6"
unit="quarter_second"/>
    <define name="AUTOSHOOT_METER_GRID" value="50" unit="meter"/>
  </section>



  <modules>
    <load name="ins_chimu_spi.xml" >
<!-- <define name="CHIMU_BIG_ENDIAN" /> -->
</load>

  </modules>


  <firmware name="fixedwing">
    <target name="ap" board="tiny_2.11">
<!-- tiny_2.11"> -->
      <define name="STRONG_WIND"/>
      <define name="WIND_INFO"/>
      <define name="WIND_INFO_RET"/>
      <define name="LOITER_TRIM"/>
      <define name="ALT_KALMAN"/>
      <define name="TELEMETRY_MODE_FBW" value="1"/>
<!-- <define name="NB_CHANNELS" value="5" /> -->
    </target>
    <target name="sim" board="pc"/>


    <subsystem name="radio_control" type="ppm"/>

    <subsystem name="gps" type="ublox" />

    <!-- Communication -->
    <subsystem name="telemetry" type="transparent">
      <configure name="MODEM_BAUD" value="B57600"/>
   </subsystem>

    <!-- Actuators -->
    <subsystem name="control"/>
    <!-- Sensors -->
    <subsystem name="navigation"/>
<!-- <subsystem name="gps" type="ublox"/> -->

    <subsystem name="spi_slave_hs"/>

  </firmware>

</airframe>

I hope you can help us.

Best Regards,

-- 
*Jorge Pantoja*
*Program Manager/Liaison*
*Phone:* +593-96160076
*e-mail:* address@hidden
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