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Re: [Paparazzi-devel] AUTO2 Standby throttle management

From: Joseph Muhlhausen
Subject: Re: [Paparazzi-devel] AUTO2 Standby throttle management
Date: Tue, 13 Aug 2013 16:00:37 +0200

I have followed Reto's advice and things improved quite a bit. Thanks again!


However, It is still far from perfect, the plane, while flying standby, drops 15m and tries to catch up then drops again. It looks like something is wrong with my pitch loop but it doesn't seem to be the gain. Attached is the flight log and a screenshot of what I think is the issue.

Inline image 1

And here my current gains.
(Umarim v2, fixedwing)

<!-- ************************* GAINS ************************* -->

  <section name="VERTICAL CONTROL" prefix="V_CTL_">
    <define name="POWER_CTL_BAT_NOMINAL" value="14.8" unit="volt"/>
    <!-- outer loop proportional gain -->
    <define name="ALTITUDE_PGAIN"        value="0.051"/> <!-- climb speed in m/s e.g. 10 m too low x 0.1 alt gain = climb_command at 1 m/s-->
    <!-- outer loop saturation -->
    <define name="ALTITUDE_MAX_CLIMB"    value="5."/> <!-- maximum climb speed in m/s -->

    <!-- auto throttle inner loop -->
    <define name="AUTO_THROTTLE_NOMINAL_CRUISE_THROTTLE"  value="0.45"/>
    <define name="AUTO_THROTTLE_MIN_CRUISE_THROTTLE"      value="0.25"/>
    <define name="AUTO_THROTTLE_MAX_CRUISE_THROTTLE"      value="0.70"/>
    <define name="AUTO_THROTTLE_LOITER_TRIM"              value="1500"/>
    <define name="AUTO_THROTTLE_DASH_TRIM"                value="-2500"/>
    <define name="AUTO_THROTTLE_CLIMB_THROTTLE_INCREMENT" value="0.15" unit="%/(m/s)"/>
    <define name="AUTO_THROTTLE_PGAIN"                    value="0.006"/>
    <define name="AUTO_THROTTLE_IGAIN"                    value="0.016"/>
    <define name="AUTO_THROTTLE_PITCH_OF_VZ_PGAIN"        value="0.09"/>
    <define name="THROTTLE_SLEW_LIMITER" value="2" unit="s"/>

 <section name="HORIZONTAL CONTROL" prefix="H_CTL_">
    <define name="COURSE_PGAIN" value="1.219"/>
    <define name="COURSE_DGAIN" value="0.219"/>
    <define name="ROLL_MAX_SETPOINT"  value="RadOfDeg(60)" />
    <define name="PITCH_MAX_SETPOINT" value="RadOfDeg(40)"/>
    <define name="PITCH_MIN_SETPOINT" value="RadOfDeg(-40)"/>
    <define name="PITCH_PGAIN" value="6000"/>
    <define name="PITCH_DGAIN" value="1.5"/>
    <define name="ELEVATOR_OF_ROLL" value="1250"/>
    <define name="ROLL_ATTITUDE_GAIN" value="7500"/>
    <define name="ROLL_RATE_GAIN"     value="1500"/>

  <section name="AGGRESSIVE" prefix="AGR_">
    <define name="BLEND_START" value="30"/><!-- Altitude Error to Initiate Aggressive Climb CANNOT BE ZERO!!-->
    <define name="BLEND_END" value="15"/><!-- Altitude Error to Blend Aggressive to Regular Climb Modes  CANNOT BE ZERO!!-->
    <define name="CLIMB_THROTTLE" value="0.80"/><!-- Gaz for Aggressive Climb -->
    <define name="CLIMB_PITCH" value="0.4"/><!-- 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"/>

On Thu, Jul 25, 2013 at 11:29 PM, <address@hidden> wrote:

Date: Thu, 25 Jul 2013 19:38:39 +0200
From: Joseph Muhlhausen <address@hidden>
To: address@hidden
Subject: Re: [Paparazzi-devel] AUTO2 Standby throttle management
Content-Type: text/plain; charset="iso-8859-1"

Thanks a lot Reto,

I will try to tweak the gains and see if it solves the issue.


 Thu, 25 Jul 2013 13:19:35 Reto B?ttner
> Hi Joseph
> That might be a problem in altitude control, probably just a tuning issue.
> Altitude is controlled both by pitch and throttle. In your case pitch
> control seems not be sensitive enough and throttle control too aggressive.
> Try enhancing the pitch gains and reducing the throttle gains. Maybe
> vertical control is generally to weak and you fly permanently in the
> aggressive flightmodes, try enhancing altitude_pgain. Additionally you
> might give more margin (blend_start and blend_end) in the aggressive
> section, especially until the vertical controller is well tuned. For more
> detailed analysis a log would be needed.
> Regards and good luck
> Reto
> 2013/7/25 Joseph Muhlhausen <address@hidden>
> > Hi all,
> >
> > I did an AUTO2 Standby test yesterday and the plane accelerates to full
> > throttle for half the circle and repeats the pattern indefinitly
> >
> > here is the video
> >
> >
> > I'm using 4.2 with the ctl_basic.xml control. I couldn't get a log of the
> > flight as my ground wasn't properly connected to the antenna.
> >
> > Any idea where that might come from? I'm not using an airspeed sensor but
> > I have one at my disposal if needed, I just want to keep things simple.
> >
> > Best,
> >
> > Joseph
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