src/Instrumentation/attitude_indicator.cxx

   1 // attitude_indicator.cxx - a vacuum-powered attitude indicator.
   2 // Written by David Megginson, started 2002.
   3 //
   4 // This file is in the Public Domain and comes with no warranty.
   5
   6 #include "attitude_indicator.hxx"
   7 #include <Main/fg_props.hxx>
   8
   9
  10 AttitudeIndicator::AttitudeIndicator ()
  11 {
  12 }
  13
  14 AttitudeIndicator::~AttitudeIndicator ()
  15 {
  16 }
  17
  18 void
  19 AttitudeIndicator::init ()
  20 {
  21                                 // TODO: allow index of pump and AI
  22                                 // to be configured.
  23     _serviceable_node =
  24         fgGetNode("/instrumentation/attitude-indicator/serviceable", true);
  25     _pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
  26     _roll_in_node = fgGetNode("/orientation/roll-deg", true);
  27     _suction_node = fgGetNode("/systems/vacuum[0]/suction-inhg", true);
  28     _pitch_out_node =
  29         fgGetNode("/instrumentation/attitude-indicator/indicated-pitch-deg",
  30                   true);
  31     _roll_out_node =
  32         fgGetNode("/instrumentation/attitude-indicator/indicated-roll-deg",
  33                   true);
  34 }
  35
  36 void
  37 AttitudeIndicator::bind ()
  38 {
  39 }
  40
  41 void
  42 AttitudeIndicator::unbind ()
  43 {
  44 }
  45
  46 void
  47 AttitudeIndicator::update (double dt)
  48 {
  49                                 // First, calculate the bogo-spin from 0 to 1.
  50                                 // All numbers are made up.
  51
  52     _spin -= 0.005 * dt;         // spin decays every 0.5% every second.
  53
  54                                 // spin increases up to 25% every second
  55                                 // if suction is available and the gauge
  56                                 // is serviceable.
  57     if (_serviceable_node->getBoolValue()) {
  58         double suction = _suction_node->getDoubleValue();
  59         double step = 0.25 * (suction / 5.0) * dt;
  60         if ((_spin + step) <= (suction / 5.0))
  61             _spin += step;
  62     }
  63     if (_spin > 1.0)
  64         _spin = 1.0;
  65     else if (_spin < 0.0)
  66         _spin = 0.0;
  67
  68                                 // Next, calculate the indicated roll
  69                                 // and pitch, introducing errors.
  70     double factor = 1.0 - ((1.0 - _spin) * (1.0 - _spin));
  71     double roll = _roll_in_node->getDoubleValue();
  72     double pitch = _pitch_in_node->getDoubleValue();
  73     roll = 35 + (factor * (roll - 35));
  74     pitch = 15 + (factor * (pitch - 15));
  75
  76     _roll_out_node->setDoubleValue(roll);
  77     _pitch_out_node->setDoubleValue(pitch);
  78 }
  79
  80 // end of attitude_indicator.cxx