//
// This file is in the Public Domain and comes with no warranty.
+// TODO:
+// - better spin-up
+
+#include <math.h> // fabs()
+
#include "attitude_indicator.hxx"
#include <Main/fg_props.hxx>
+#include <Main/util.hxx>
AttitudeIndicator::AttitudeIndicator ()
{
// TODO: allow index of pump and AI
// to be configured.
- _serviceable_node =
- fgGetNode("/instrumentation/attitude-indicator/serviceable", true);
_pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
_roll_in_node = fgGetNode("/orientation/roll-deg", true);
_suction_node = fgGetNode("/systems/vacuum[0]/suction-inhg", true);
+ _tumble_flag_node =
+ fgGetNode("/instrumentation/attitude-indicator/config/tumble-flag",
+ true);
+ _caged_node =
+ fgGetNode("/instrumentation/attitude-indicator/caged-flag", true);
+ _tumble_node =
+ fgGetNode("/instrumentation/attitude-indicator/tumble-norm", true);
+ _pitch_int_node =
+ fgGetNode("/instrumentation/attitude-indicator/internal-pitch-deg",
+ true);
+ _roll_int_node =
+ fgGetNode("/instrumentation/attitude-indicator/internal-roll-deg",
+ true);
_pitch_out_node =
fgGetNode("/instrumentation/attitude-indicator/indicated-pitch-deg",
true);
void
AttitudeIndicator::bind ()
{
+ fgTie("/instrumentation/attitude-indicator/serviceable",
+ &_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
+ fgTie("/instrumentation/attitude-indicator/spin",
+ &_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
}
void
AttitudeIndicator::unbind ()
{
+ fgUntie("/instrumentation/attitude-indicator/serviceable");
+ fgUntie("/instrumentation/attitude-indicator/spin");
}
void
AttitudeIndicator::update (double dt)
{
- // First, calculate the bogo-spin from 0 to 1.
- // All numbers are made up.
-
- _spin -= 0.01 * dt; // spin decays every 1% every second.
-
- // spin increases up to 10% every second
- // if suction is available and the gauge
- // is serviceable.
- if (_serviceable_node->getBoolValue()) {
- double suction = _suction_node->getDoubleValue();
- double step = 0.10 * (suction / 5.0) * dt;
- if ((_spin + step) <= (suction / 5.0))
- _spin += step;
+ // If it's caged, it doesn't indicate
+ if (_caged_node->getBoolValue()) {
+ _roll_int_node->setDoubleValue(0.0);
+ _pitch_int_node->setDoubleValue(0.0);
+ return;
}
- // Next, calculate the indicated roll
- // and pitch, introducing errors if
- // the spin is less than 0.8 (80%).
+ // Get the spin from the gyro
+ _gyro.set_power_norm(_suction_node->getDoubleValue()/5.0);
+ _gyro.update(dt);
+ double spin = _gyro.get_spin_norm();
+
+ // Calculate the responsiveness
+ double responsiveness = spin * spin * spin * spin * spin * spin;
+
+ // Get the indicated roll and pitch
double roll = _roll_in_node->getDoubleValue();
double pitch = _pitch_in_node->getDoubleValue();
- if (_spin < 0.8) {
- // TODO
+
+ // Calculate the tumble for the
+ // next pass.
+ if (_tumble_flag_node->getBoolValue()) {
+ double tumble = _tumble_node->getDoubleValue();
+ if (fabs(roll) > 45.0) {
+ double target = (fabs(roll) - 45.0) / 45.0;
+ target *= target; // exponential past +-45 degrees
+ if (roll < 0)
+ target = -target;
+
+ if (fabs(target) > fabs(tumble))
+ tumble = target;
+
+ if (tumble > 1.0)
+ tumble = 1.0;
+ else if (tumble < -1.0)
+ tumble = -1.0;
+ }
+ // Reerect in 5 minutes
+ double step = dt/300.0;
+ if (tumble < -step)
+ tumble += step;
+ else if (tumble > step)
+ tumble -= step;
+
+ roll += tumble * 45;
+ _tumble_node->setDoubleValue(tumble);
+ }
+
+ roll = fgGetLowPass(_roll_int_node->getDoubleValue(), roll,
+ responsiveness);
+ pitch = fgGetLowPass(_pitch_int_node->getDoubleValue(), pitch,
+ responsiveness);
+
+ // Assign the new values
+ _roll_int_node->setDoubleValue(roll);
+ _pitch_int_node->setDoubleValue(pitch);
+
+ // add in a gyro underspin "error" if gyro is spinning too slowly
+ const double spin_thresh = 0.8;
+ const double max_roll_error = 40.0;
+ const double max_pitch_error = 12.0;
+ double roll_error;
+ double pitch_error;
+ if ( spin <= spin_thresh ) {
+ double roll_error_factor = (spin_thresh - spin) / spin_thresh;
+ double pitch_error_factor = (spin_thresh - spin) / spin_thresh;
+ roll_error = roll_error_factor * roll_error_factor * max_roll_error;
+ pitch_error = pitch_error_factor * pitch_error_factor * max_pitch_error;
+ } else {
+ roll_error = 0.0;
+ pitch_error = 0.0;
}
- _roll_out_node->setDoubleValue(roll);
- _pitch_out_node->setDoubleValue(pitch);
+
+ _roll_out_node->setDoubleValue(roll + roll_error);
+ _pitch_out_node->setDoubleValue(pitch + pitch_error);
}
// end of attitude_indicator.cxx