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 // TODO:
   7 // - tumble
   8 // - better spin-up
   9
  10 #include "attitude_indicator.hxx"
  11 #include <Main/fg_props.hxx>
  12
  13
  14 AttitudeIndicator::AttitudeIndicator ()
  15 {
  16 }
  17
  18 AttitudeIndicator::~AttitudeIndicator ()
  19 {
  20 }
  21
  22 void
  23 AttitudeIndicator::init ()
  24 {
  25                                 // TODO: allow index of pump and AI
  26                                 // to be configured.
  27     _pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
  28     _roll_in_node = fgGetNode("/orientation/roll-deg", true);
  29     _suction_node = fgGetNode("/systems/vacuum[0]/suction-inhg", true);
  30     _pitch_out_node =
  31         fgGetNode("/instrumentation/attitude-indicator/indicated-pitch-deg",
  32                   true);
  33     _roll_out_node =
  34         fgGetNode("/instrumentation/attitude-indicator/indicated-roll-deg",
  35                   true);
  36 }
  37
  38 void
  39 AttitudeIndicator::bind ()
  40 {
  41     fgTie("/instrumentation/attitude-indicator/serviceable",
  42           &_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
  43     fgTie("/instrumentation/attitude-indicator/spin",
  44           &_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
  45 }
  46
  47 void
  48 AttitudeIndicator::unbind ()
  49 {
  50     fgUntie("/instrumentation/attitude-indicator/serviceable");
  51     fgUntie("/instrumentation/attitude-indicator/spin");
  52 }
  53
  54 void
  55 AttitudeIndicator::update (double dt)
  56 {
  57                                 // Get the spin from the gyro
  58     _gyro.set_power_norm(_suction_node->getDoubleValue()/5.0);
  59     _gyro.update(dt);
  60     double spin = _gyro.get_spin_norm();
  61
  62                                 // Next, calculate the indicated roll
  63                                 // and pitch, introducing errors.
  64     double factor = 1.0 - ((1.0 - spin) * (1.0 - spin) * (1.0 - spin));
  65     double roll = _roll_in_node->getDoubleValue();
  66     double pitch = _pitch_in_node->getDoubleValue();
  67     roll = 35 + (factor * (roll - 35));
  68     pitch = 15 + (factor * (pitch - 15));
  69
  70     _roll_out_node->setDoubleValue(roll);
  71     _pitch_out_node->setDoubleValue(pitch);
  72 }
  73
  74 // end of attitude_indicator.cxx