<?xml version="1.0"?>

<!-- Lockheed 1049 autopilot :

     Autothrottle and true heading hold are test modes (speed-up).

     Autothrottle simulates slower human behaviour (virtual copilot).


     Known problems:
     - roll on heading hold near max speed (260 kt) : might be the FDM (?).
     Solved by a rudder trim, which unlocks the roll.
-->

<!-- Each component is evaluated in the order specified.  You can make up -->
<!-- property names to pass the result of one component on to a subsequent -->
<!-- component. -->


<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                                                 -->
  <!-- =============================================================== -->

  <!-- .............................................. -->
  <!-- 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>-20.0</u_min> <!-- minimum output clamp -->
      <u_max>20.0</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>0.1</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>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>

  <!-- Stage #3 drives the rudder to unlock roll. -->
  <pid-controller>
    <name>Heading Bug Hold (DG based) Stage 3</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/rudder</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>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-0.0025</u_min> <!-- minimum output clamp -->
      <u_max>0.0025</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>-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>-20.0</u_min> <!-- minimum output clamp -->
      <u_max>20.0</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>0.1</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>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>

  <!-- Stage #3 drives the rudder to unlock roll. -->
  <pid-controller>
    <name>True Heading Hold (DG based) Stage 3</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/rudder</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>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>-0.0025</u_min> <!-- minimum output clamp -->
      <u_max>0.0025</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>-0.05</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>

  <!-- ........................................... -->
  <!-- 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>/instrumentation/altimeter/indicated-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>0.1</Kp>          <!-- proportional gain -->
      <Ki>0.0</Ki>          <!-- integral gain -->
      <u_min>-15.00</u_min> <!-- minimum output clamp -->
      <u_max>20.00</u_max>  <!-- maximum output clamp -->
    </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>-0.01</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</name>
    <debug>false</debug>
    <enable>
      <prop>/autopilot/locks/speed</prop>
      <value>speed-with-throttle</value>
    </enable>
    <input>
      <prop>/instrumentation/airspeed-indicator/indicated-speed-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>10.0</Ti>       <!-- integrator time -->
      <Td>0.00001</Td>    <!-- derivator time -->
      <u_min>0.0</u_min>  <!-- minimum output clamp -->
      <u_max>1.0</u_max>  <!-- maximum output clamp -->
    </config>
  </pid-controller>

</PropertyList>
