AvroVulcanB2/Systems/autopilot2.xml

<?xml version="1.0"?>
 




<PropertyList>

  <!-- =============================================================== -->
  <!-- Prediction filters                                              -->
  <!-- =============================================================== -->

  <predict-simple>
     <input>/autopilot/internal/nav1-track-error-deg</input>
     <output>/autopilot/internal/nav1-track-error-lookahead-deg</output>
     <seconds>8.0</seconds>
     <filter-gain>0.0</filter-gain>
  </predict-simple>

  <!-- =============================================================== -->
  <!-- Roll Axis Modes                                                 -->
  <!-- =============================================================== -->

  <!-- Wing leveler --> 
  <pid-controller>
    <name>Wing Leveler (Turn Coordinator based)</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>wing-leveler</value>
    </enable>
    <input>
      <prop>/instrumentation/turn-indicator/indicated-turn-rate</prop>
    </input>
    <reference>
      <value>0.0</value>
    </reference>
    <output>
      <prop>/controls/flight/aileron</prop>
    </output>
    <config>
      <Kp>0.5</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Heading Bug Hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target roll based on diff between current heading -->
  <!-- and heading bug. -->
  <pid-controller>
    <name>Heading Bug Hold (FDM mag heading based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>dg-heading-hold</value>
    </enable>
    <input>
      <prop>/autopilot/internal/fdm-heading-bug-error-deg</prop>
    </input>
    <reference>
      <value>0.0</value>
    </reference>
    <output>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </output>
    <config>
      <Kp>-1.0</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>     <!-- input value weighing factor -->
      <alpha>0.1</alpha>   <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>   <!-- input value weighing factor for -->
                           <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>     <!-- derivator time -->
      <u_min>-30.0</u_min> <!-- minimum output clamp -->
      <u_max>30.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Stage #2 drives the ailerons to achieve the desired roll deg. -->
  <pid-controller>
    <name>Heading Bug Hold (DG based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>dg-heading-hold</value>
    </enable>
    <input>
      <prop>/orientation/roll-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/aileron</prop>
    </output>
    <config>
      <Kp>0.02</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- True Heading hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target roll based on diff between current heading -->
  <!-- and target heading. -->
  <pid-controller>
    <name>True Heading Hold (DG based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>true-heading-hold</value>
    </enable>
    <input>
      <prop>/autopilot/internal/true-heading-error-deg</prop>
    </input>
    <reference>
      <value>0.0</value>
    </reference>
    <output>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </output>
    <config>
      <Kp>-3.5</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>     <!-- input value weighing factor -->
      <alpha>0.1</alpha>   <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>   <!-- input value weighing factor for -->
                           <!-- unfiltered derivative error -->
      <Ti>2.9</Ti>        <!-- integrator time -->
      <Td>0.0000001</Td>     <!-- derivator time -->
      <u_min>-35.0</u_min> <!-- minimum output clamp -->
      <u_max>35.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Stage #2 drives the ailerons to achieve the desired roll deg. -->
  <pid-controller>
    <name>True Heading Hold (DG based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>true-heading-hold</value>
    </enable>
    <input>
      <prop>/orientation/roll-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/aileron</prop>
    </output>
    <config>
      <Kp>0.02</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>5.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-3.0</u_min> <!-- minimum output clamp -->
      <u_max>3.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Nav1 hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target roll based on diff between current heading -->
  <!-- and target heading. -->
  <pid-controller>
    <name>Nav1 Hold Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>nav1-hold</value>
    </enable>
    <input>
      <prop>/autopilot/internal/nav1-track-error-deg</prop>
    </input>
    <reference>
      <value>0.0</value>
    </reference>
    <output>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </output>
    <config>
      <Kp>-1.0</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>     <!-- input value weighing factor -->
      <alpha>0.1</alpha>   <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>   <!-- input value weighing factor for -->
                           <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>
      <u_min>-30.0</u_min> <!-- minimum output clamp -->
      <u_max>30.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Stage #2 drives the ailerons to achieve the desired roll deg. -->
  <pid-controller>
    <name>Nav1 Hold Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>nav1-hold</value>
    </enable>
    <input>
      <prop>/orientation/roll-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/aileron</prop>
    </output>
    <config>
      <Kp>0.02</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>


  <!-- Second Stage #2 drives the rudder. -->
  <pid-controller>
    <name>Nav1 Hold Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>nav1-hold</value>
    </enable>
    <input>
      <prop>/orientation/roll-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/rudder</prop>
    </output>
    <config>
      <Kp>0.005</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.000000001</Td>    <!-- derivator time -->
      <u_min>-0.25</u_min> <!-- minimum output clamp -->
      <u_max>0.25</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  
    <!-- Tacan hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target roll based on diff between current heading -->
  <!-- and target heading. -->
  <pid-controller>
    <name>Tacan Hold (DG based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>tacan-hold</value>
    </enable>
     <input>
      <prop>/autopilot/internal/fdm-heading-bug-error-deg</prop>
    </input>
    <reference>
      <value>0.0</value>
    </reference>
    <output>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </output>
    <config>
      <Kp>-1.0</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>     <!-- input value weighing factor -->
      <alpha>0.1</alpha>   <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>   <!-- input value weighing factor for -->
                           <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>     <!-- derivator time -->
      <u_min>-30.0</u_min> <!-- minimum output clamp -->
      <u_max>30.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Stage #2 drives the ailerons to achieve the desired roll deg. -->
  <pid-controller>
    <name>Tacan Hold (DG based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/heading</prop>
      <value>tacan-hold</value>
    </enable>
    <input>
      <prop>/orientation/roll-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-roll-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/aileron</prop>
    </output>
    <config>
      <Kp>0.05</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>5.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-3.0</u_min> <!-- minimum output clamp -->
      <u_max>3.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>


 <!-- =============================================================== -->
 <!-- Pitch Axis Modes                                                -->
 <!-- =============================================================== -->

  <!-- Simple pitch hold --> 
 <pid-controller>
    <name>Pitch hold</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>pitch-hold</value>
    </enable>
    <input>
      <prop>/orientation/pitch-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-pitch-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.005</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>1.0</Ti>        <!-- integrator time 1.0 -->
      <Td>0.00001</Td>    <!-- derivator time  0.00001 -->
      <u_min>-0.4</u_min> <!-- minimum output clamp -->
      <u_max>0.4</u_max>  <!-- maximum output clamp -->
    </config>
   </pid-controller>

 <!-- Simple angle of attack hold --> 
 <pid-controller>
    <name>AOA hold</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>aoa-hold</value>
    </enable>
    <input>
      <prop>/orientation/alpha-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-aoa-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.005</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>0.5</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-0.4</u_min> <!-- minimum output clamp -->
      <u_max>0.4</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Altitude hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target rate of climb based on diff between current alt -->
  <!-- and target altitude. -->
  <pi-simple-controller>
    <name>Altitude Hold (Altimeter based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>altitude-hold</value>
    </enable>
    <input>
      <prop>/position/altitude-ft</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-altitude-ft</prop>
    </reference>
    <output>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </output>
    <config>
      <Kp>0.25</Kp>          <!-- proportional gain -->
      <Ki>0.0</Ki>          <!-- integral gain -->
      <u_min>-33.33</u_min> <!-- minimum output clamp -16.67-->
      <u_max>33.33</u_max>   <!-- maximum output clamp 33.33-->
    </config>
  </pi-simple-controller>

  <!-- Stage #2 drives the elevator-trim to achieve the desired climb rate. -->
  <pid-controller>
    <name>Altitude Hold (Altimeter based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>altitude-hold</value>
    </enable>
    <input>
      <prop>/velocities/vertical-speed-fps</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
	    <Kp>-0.0025</Kp>      <!-- proportional gain -0.01 -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time  10.0 -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-0.5</u_min> <!-- minimum output clamp -->
      <u_max>0.5</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- AGL hold.  2 stage cascade controller. -->

  <!-- Stage #1 sets target rate of climb based on diff between current agl -->
  <!-- and target agl. -->
  <pid-controller>
    <name>AGL Hold (Altimeter based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>agl-hold</value>
    </enable>
    <input>
      <prop>/position/altitude-agl-ft</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-agl-ft</prop>
    </reference>
    <output>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </output>
    <config>
      <Kp>1.0</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>25.0</Ti>    <!-- integrator time -->
      <Td>0.00000001</Td>    <!-- derivator time -->
      <u_min>-45.33</u_min> <!-- minimum output clamp -->
      <u_max>45.33</u_max> <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Stage #2 drives the elevator-trim to achieve the desired climb rate. -->
  <pid-controller>
    <name>Altitude Hold (Altimeter based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>agl-hold</value>
    </enable>
    <input>
      <prop>/velocities/vertical-speed-fps</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.0025</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

  <!-- Glideslope hold. -->

  <!-- Stage #2 drives the elevator-trim to achieve the desired climb rate. -->
  <pid-controller>
    <name>Glideslop Hold</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>gs1-hold</value>
    </enable>
    <input>
      <prop>/velocities/vertical-speed-fps</prop>
    </input>
    <reference>
      <prop>/instrumentation/nav[0]/gs-rate-of-climb</prop>
    </reference>
     <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.005</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>


  <!-- vertical speed hold -->
  <pid-controller>
    <name>Vertical Speed Hold</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>vertical-speed-hold</value>
    </enable>
    <input>
      <prop>/velocities/vertical-speed-fps</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/vertical-speed-fpm</prop>
      <scale>0.01667</scale>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.0025</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>


 <!-- =============================================================== -->
 <!-- Velocity Modes                                                  -->
 <!-- =============================================================== -->

 <!-- Auto throttle --> 
 <pid-controller>
    <name>Auto Throttle (5 sec lookahead)</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/speed</prop>
      <value>speed-with-throttle</value>
    </enable>
    <input>
      <prop>/autopilot/internal/lookahead-5-sec-airspeed-kt</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-speed-kt</prop>
    </reference>
    <output>
      <prop>/controls/engines/engine[0]/throttle</prop>
      <prop>/controls/engines/engine[1]/throttle</prop>
      <prop>/controls/engines/engine[2]/throttle</prop>
      <prop>/controls/engines/engine[3]/throttle</prop>
    </output>
    <config>
      <Kp>0.1</Kp>        <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>5.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>0.0</u_min>  <!-- minimum output clamp -->
      <u_max>1.00</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

 <!-- Hold speed by varying pitch (Two stage cascading controller) --> 
 <pid-controller>
    <name>Speed hold (vary pitch) Stage #1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/speed</prop>
      <value>speed-with-pitch</value>
    </enable>
    <input>
      <prop>/autopilot/internal/lookahead-5-sec-airspeed-kt</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-speed-kt</prop>
    </reference>
    <output>
      <prop>/autopilot/settings/target-pitch-deg</prop>
    </output>
    <config>
      <Kp>-1.0</Kp>       <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>1.0</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-15.0</u_min><!-- minimum output clamp -->
      <u_max>15.0</u_max> <!-- maximum output clamp -->
    </config>
  </pid-controller>

 <pid-controller>
    <name>Speed hold (vary pitch) Stage #2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/speed</prop>
      <value>speed-with-pitch</value>
    </enable>
    <input>
      <prop>/orientation/pitch-deg</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-pitch-deg</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
      <Kp>-0.05</Kp>      <!-- proportional gain -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>1.0</Ti>        <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1.0</u_min> <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

    <!-- Terrain follow.  2 stage cascade controller. -->

  <!-- Stage #1 sets target rate of climb based on diff between current alt -->
  <!-- and target altitude. -->
  <pi-simple-controller>
    <name>Altitude Hold (Altimeter based) Stage 1</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>terrain-follow</value>
    </enable>
    <input>
      <prop>/position/altitude-ft</prop>
    </input>
    <reference>
      <prop>/autopilot/settings/target-follow-altitude-ft</prop>
    </reference>
    <output>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </output>
    <config>
      <Kp>0.25</Kp>          <!-- proportional gain -->
      <Ki>0.0</Ki>          <!-- integral gain -->
      <u_min>-120.00</u_min> <!-- minimum output clamp -16.67-->
      <u_max>300.00</u_max>   <!-- maximum output clamp 33.33-->
    </config>
  </pi-simple-controller>

  <!-- Stage #2 drives the elevator-trim to achieve the desired climb rate. -->
  <pid-controller>
    <name>Altitude Hold (Altimeter based) Stage 2</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/altitude</prop>
      <value>terrain-follow</value>
    </enable>
    <input>
      <prop>/velocities/vertical-speed-fps</prop>
    </input>
    <reference>
      <prop>/autopilot/internal/target-climb-rate-fps</prop>
    </reference>
    <output>
      <prop>/controls/flight/elevator-trim</prop>
    </output>
    <config>
	    <Kp>-0.0025</Kp>      <!-- proportional gain -0.01 -->
      <beta>1.0</beta>    <!-- input value weighing factor -->
      <alpha>0.1</alpha>  <!-- low pass filter weighing factor -->
      <gamma>0.0</gamma>  <!-- input value weighing factor for -->
                          <!-- unfiltered derivative error -->
      <Ti>10.0</Ti>       <!-- integrator time  10.0 -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-1</u_min> <!-- minimum output clamp -->
      <u_max>1</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>


</PropertyList>