attitude_indicator_electric.cxx

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// attitude_indicator_electric.hxx - an electrically-powered attitude indicator.
// Written by David Megginson, started 2002.
// Ported to Electric by Benedikt Wolf 2023
// Enhanced by Benedikt Hallinger, 2023
//
// This file is in the Public Domain and comes with no warranty.
 
 
#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif
 
#include <simgear/compiler.h>
 
#include <iostream>
#include <string>
#include <sstream>
 
#include <cmath>    // fabs()
 
#include "attitude_indicator_electric.hxx"
#include <Main/fg_props.hxx>
#include <Main/util.hxx>
 
using std::string;
 
AttitudeIndicatorElectric::AttitudeIndicatorElectric ( SGPropertyNode *node )
:
spin_thresh(0.8),
max_roll_error(40.0),
max_pitch_error(12.0)
{
    SGPropertyNode* gyro_cfg = node->getChild("gyro", 0, true);
    _gyro_spin_up = gyro_cfg->getDoubleValue("spin-up-sec", 4.0);
    _gyro_spin_down = gyro_cfg->getDoubleValue("spin-down-sec", 180.0);
 
    readConfig(node, "attitude-indicator-electric");
}
 
AttitudeIndicatorElectric::~AttitudeIndicatorElectric ()
{
}
 
void
AttitudeIndicatorElectric::init ()
{
        string branch = nodePath();
 
        SGPropertyNode *node    = fgGetNode(branch, true );
        SGPropertyNode *n;
 
        _pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
        _roll_in_node = fgGetNode("/orientation/roll-deg", true);
        SGPropertyNode *cnode = node->getChild("config", 0, true);
        _tumble_flag_node = cnode->getChild("tumble-flag", 0, true);
        _caged_node = node->getChild("caged-flag", 0, true);
        _tumble_node = node->getChild("tumble-norm", 0, true);
        if( ( n = cnode->getChild("spin-thresh", 0, false ) ) != NULL )
                spin_thresh = n->getDoubleValue();
        if( ( n = cnode->getChild("max-roll-error-deg", 0, false ) ) != NULL )
                max_roll_error = n->getDoubleValue();
        if( ( n = cnode->getChild("max-pitch-error-deg", 0, false ) ) != NULL )
                max_pitch_error = n->getDoubleValue();
        _pitch_int_node = node->getChild("internal-pitch-deg", 0, true);
        _roll_int_node = node->getChild("internal-roll-deg", 0, true);
        _pitch_out_node = node->getChild("indicated-pitch-deg", 0, true);
        _roll_out_node = node->getChild("indicated-roll-deg", 0, true);
        _off_node         = node->getChild("off-flag", 0, true);
        _spin_node = node->getChild("spin", 0, true);
 
    SGPropertyNode* gyro_node = node->getChild("gyro", 0, true);
    _gyro_spin_up_node = gyro_node->getChild("spin-up-sec", 0, true);
    _gyro_spin_down_node = gyro_node->getChild("spin-down-sec", 0, true);
    if (!_gyro_spin_up_node->hasValue())
        _gyro_spin_up_node->setDoubleValue(_gyro_spin_up);
    if (!_gyro_spin_down_node->hasValue())
        _gyro_spin_down_node->setDoubleValue(_gyro_spin_down);
 
    initServicePowerProperties(node);
 
        reinit();
}
 
void
AttitudeIndicatorElectric::reinit ()
{
        _roll_int_node->setDoubleValue(0.0);
        _pitch_int_node->setDoubleValue(0.0);
        _gyro.reinit();
}
 
void
AttitudeIndicatorElectric::update (double dt)
{
        // 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;
        }
 
        // Get the spin from the gyro
        _gyro.set_power_norm(isServiceableAndPowered());
    _gyro.set_spin_up(_gyro_spin_up_node->getDoubleValue());
    _gyro.set_spin_down(_gyro_spin_down_node->getDoubleValue());
    _gyro.set_spin_norm(_spin_node->getDoubleValue());
    _gyro.update(dt);
        double spin = _gyro.get_spin_norm();
        _spin_node->setDoubleValue( spin );
        
        _off_node->setBoolValue( !( isServiceableAndPowered() && spin >= 0.25 ) );
 
        // 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();
 
        // 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
        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 + roll_error);
        _pitch_out_node->setDoubleValue(pitch + pitch_error);
}
 
// end of attitude_indicator_electric.cxx