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flightgear/src/Autopilot/xmlauto.cxx
mfranz 80467ed6d0 Harald JOHNSEN: initialize elapsedTime
2007-07-09 17:15:11 +00:00

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// xmlauto.cxx - a more flexible, generic way to build autopilots
//
// Written by Curtis Olson, started January 2004.
//
// Copyright (C) 2004 Curtis L. Olson - http://www.flightgear.org/~curt
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
//
// $Id$
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <simgear/structure/exception.hxx>
#include <simgear/misc/sg_path.hxx>
#include <simgear/sg_inlines.h>
#include <Main/fg_props.hxx>
#include <Main/globals.hxx>
#include <Main/util.hxx>
#include "xmlauto.hxx"
FGPIDController::FGPIDController( SGPropertyNode *node ):
debug( false ),
y_n( 0.0 ),
r_n( 0.0 ),
y_scale( 1.0 ),
r_scale( 1.0 ),
y_offset( 0.0 ),
r_offset( 0.0 ),
Kp( 0.0 ),
alpha( 0.1 ),
beta( 1.0 ),
gamma( 0.0 ),
Ti( 0.0 ),
Td( 0.0 ),
u_min( 0.0 ),
u_max( 0.0 ),
ep_n_1( 0.0 ),
edf_n_1( 0.0 ),
edf_n_2( 0.0 ),
u_n_1( 0.0 ),
desiredTs( 0.0 ),
elapsedTime( 0.0 )
{
int i;
for ( i = 0; i < node->nChildren(); ++i ) {
SGPropertyNode *child = node->getChild(i);
string cname = child->getName();
string cval = child->getStringValue();
if ( cname == "name" ) {
name = cval;
} else if ( cname == "debug" ) {
debug = child->getBoolValue();
} else if ( cname == "enable" ) {
// cout << "parsing enable" << endl;
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
// cout << "prop = " << prop->getStringValue() << endl;
enable_prop = fgGetNode( prop->getStringValue(), true );
} else {
// cout << "no prop child" << endl;
}
SGPropertyNode *val = child->getChild( "value" );
if ( val != NULL ) {
enable_value = val->getStringValue();
}
SGPropertyNode *pass = child->getChild( "honor-passive" );
if ( pass != NULL ) {
honor_passive = pass->getBoolValue();
}
} else if ( cname == "input" ) {
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
input_prop = fgGetNode( prop->getStringValue(), true );
}
prop = child->getChild( "scale" );
if ( prop != NULL ) {
y_scale = prop->getDoubleValue();
}
prop = child->getChild( "offset" );
if ( prop != NULL ) {
y_offset = prop->getDoubleValue();
}
} else if ( cname == "reference" ) {
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
r_n_prop = fgGetNode( prop->getStringValue(), true );
} else {
prop = child->getChild( "value" );
if ( prop != NULL ) {
r_n_value = prop->getDoubleValue();
}
}
prop = child->getChild( "scale" );
if ( prop != NULL ) {
r_scale = prop->getDoubleValue();
}
prop = child->getChild( "offset" );
if ( prop != NULL ) {
r_offset = prop->getDoubleValue();
}
} else if ( cname == "output" ) {
int i = 0;
SGPropertyNode *prop;
while ( (prop = child->getChild("prop", i)) != NULL ) {
SGPropertyNode *tmp = fgGetNode( prop->getStringValue(), true );
output_list.push_back( tmp );
i++;
}
} else if ( cname == "config" ) {
SGPropertyNode *prop;
prop = child->getChild( "Ts" );
if ( prop != NULL ) {
desiredTs = prop->getDoubleValue();
}
prop = child->getChild( "Kp" );
if ( prop != NULL ) {
Kp = prop->getDoubleValue();
}
prop = child->getChild( "beta" );
if ( prop != NULL ) {
beta = prop->getDoubleValue();
}
prop = child->getChild( "alpha" );
if ( prop != NULL ) {
alpha = prop->getDoubleValue();
}
prop = child->getChild( "gamma" );
if ( prop != NULL ) {
gamma = prop->getDoubleValue();
}
prop = child->getChild( "Ti" );
if ( prop != NULL ) {
Ti = prop->getDoubleValue();
}
prop = child->getChild( "Td" );
if ( prop != NULL ) {
Td = prop->getDoubleValue();
}
prop = child->getChild( "u_min" );
if ( prop != NULL ) {
u_min = prop->getDoubleValue();
}
prop = child->getChild( "u_max" );
if ( prop != NULL ) {
u_max = prop->getDoubleValue();
}
} else {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Error in autopilot config logic" );
if ( name.length() ) {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Section = " << name );
}
}
}
}
/*
* Roy Vegard Ovesen:
*
* Ok! Here is the PID controller algorithm that I would like to see
* implemented:
*
* delta_u_n = Kp * [ (ep_n - ep_n-1) + ((Ts/Ti)*e_n)
* + (Td/Ts)*(edf_n - 2*edf_n-1 + edf_n-2) ]
*
* u_n = u_n-1 + delta_u_n
*
* where:
*
* delta_u : The incremental output
* Kp : Proportional gain
* ep : Proportional error with reference weighing
* ep = beta * r - y
* where:
* beta : Weighing factor
* r : Reference (setpoint)
* y : Process value, measured
* e : Error
* e = r - y
* Ts : Sampling interval
* Ti : Integrator time
* Td : Derivator time
* edf : Derivate error with reference weighing and filtering
* edf_n = edf_n-1 / ((Ts/Tf) + 1) + ed_n * (Ts/Tf) / ((Ts/Tf) + 1)
* where:
* Tf : Filter time
* Tf = alpha * Td , where alpha usually is set to 0.1
* ed : Unfiltered derivate error with reference weighing
* ed = gamma * r - y
* where:
* gamma : Weighing factor
*
* u : absolute output
*
* Index n means the n'th value.
*
*
* Inputs:
* enabled ,
* y_n , r_n , beta=1 , gamma=0 , alpha=0.1 ,
* Kp , Ti , Td , Ts (is the sampling time available?)
* u_min , u_max
*
* Output:
* u_n
*/
void FGPIDController::update( double dt ) {
double ep_n; // proportional error with reference weighing
double e_n; // error
double ed_n; // derivative error
double edf_n; // derivative error filter
double Tf; // filter time
double delta_u_n = 0.0; // incremental output
double u_n = 0.0; // absolute output
double Ts; // sampling interval (sec)
elapsedTime += dt;
if ( elapsedTime <= desiredTs ) {
// do nothing if time step is not positive (i.e. no time has
// elapsed)
return;
}
Ts = elapsedTime;
elapsedTime = 0.0;
if (enable_prop != NULL && enable_prop->getStringValue() == enable_value) {
if ( !enabled ) {
// first time being enabled, seed u_n with current
// property tree value
u_n = output_list[0]->getDoubleValue();
// and clip
if ( u_n < u_min ) { u_n = u_min; }
if ( u_n > u_max ) { u_n = u_max; }
u_n_1 = u_n;
}
enabled = true;
} else {
enabled = false;
}
if ( enabled && Ts > 0.0) {
if ( debug ) cout << "Updating " << name
<< " Ts " << Ts << endl;
double y_n = 0.0;
if ( input_prop != NULL ) {
y_n = input_prop->getDoubleValue() * y_scale + y_offset;
}
double r_n = 0.0;
if ( r_n_prop != NULL ) {
r_n = r_n_prop->getDoubleValue() * r_scale + r_offset;
} else {
r_n = r_n_value;
}
if ( debug ) cout << " input = " << y_n << " ref = " << r_n << endl;
// Calculates proportional error:
ep_n = beta * r_n - y_n;
if ( debug ) cout << " ep_n = " << ep_n;
if ( debug ) cout << " ep_n_1 = " << ep_n_1;
// Calculates error:
e_n = r_n - y_n;
if ( debug ) cout << " e_n = " << e_n;
// Calculates derivate error:
ed_n = gamma * r_n - y_n;
if ( debug ) cout << " ed_n = " << ed_n;
if ( Td > 0.0 ) {
// Calculates filter time:
Tf = alpha * Td;
if ( debug ) cout << " Tf = " << Tf;
// Filters the derivate error:
edf_n = edf_n_1 / (Ts/Tf + 1)
+ ed_n * (Ts/Tf) / (Ts/Tf + 1);
if ( debug ) cout << " edf_n = " << edf_n;
} else {
edf_n = ed_n;
}
// Calculates the incremental output:
if ( Ti > 0.0 ) {
delta_u_n = Kp * ( (ep_n - ep_n_1)
+ ((Ts/Ti) * e_n)
+ ((Td/Ts) * (edf_n - 2*edf_n_1 + edf_n_2)) );
}
if ( debug ) {
cout << " delta_u_n = " << delta_u_n << endl;
cout << "P:" << Kp * (ep_n - ep_n_1)
<< " I:" << Kp * ((Ts/Ti) * e_n)
<< " D:" << Kp * ((Td/Ts) * (edf_n - 2*edf_n_1 + edf_n_2))
<< endl;
}
// Integrator anti-windup logic:
if ( delta_u_n > (u_max - u_n_1) ) {
delta_u_n = u_max - u_n_1;
if ( debug ) cout << " max saturation " << endl;
} else if ( delta_u_n < (u_min - u_n_1) ) {
delta_u_n = u_min - u_n_1;
if ( debug ) cout << " min saturation " << endl;
}
// Calculates absolute output:
u_n = u_n_1 + delta_u_n;
if ( debug ) cout << " output = " << u_n << endl;
// Updates indexed values;
u_n_1 = u_n;
ep_n_1 = ep_n;
edf_n_2 = edf_n_1;
edf_n_1 = edf_n;
// passive_ignore == true means that we go through all the
// motions, but drive the outputs. This is analogous to
// running the autopilot with the "servos" off. This is
// helpful for things like flight directors which position
// their vbars from the autopilot computations.
if ( passive_mode->getBoolValue() && honor_passive ) {
// skip output step
} else {
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( u_n );
}
}
} else if ( !enabled ) {
ep_n = 0.0;
edf_n = 0.0;
// Updates indexed values;
u_n_1 = u_n;
ep_n_1 = ep_n;
edf_n_2 = edf_n_1;
edf_n_1 = edf_n;
}
}
FGPISimpleController::FGPISimpleController( SGPropertyNode *node ):
proportional( false ),
Kp( 0.0 ),
offset_prop( NULL ),
offset_value( 0.0 ),
integral( false ),
Ki( 0.0 ),
int_sum( 0.0 ),
clamp( false ),
debug( false ),
y_n( 0.0 ),
r_n( 0.0 ),
y_scale( 1.0 ),
r_scale ( 1.0 ),
u_min( 0.0 ),
u_max( 0.0 )
{
int i;
for ( i = 0; i < node->nChildren(); ++i ) {
SGPropertyNode *child = node->getChild(i);
string cname = child->getName();
string cval = child->getStringValue();
if ( cname == "name" ) {
name = cval;
} else if ( cname == "debug" ) {
debug = child->getBoolValue();
} else if ( cname == "enable" ) {
// cout << "parsing enable" << endl;
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
// cout << "prop = " << prop->getStringValue() << endl;
enable_prop = fgGetNode( prop->getStringValue(), true );
} else {
// cout << "no prop child" << endl;
}
SGPropertyNode *val = child->getChild( "value" );
if ( val != NULL ) {
enable_value = val->getStringValue();
}
} else if ( cname == "input" ) {
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
input_prop = fgGetNode( prop->getStringValue(), true );
}
prop = child->getChild( "scale" );
if ( prop != NULL ) {
y_scale = prop->getDoubleValue();
}
} else if ( cname == "reference" ) {
SGPropertyNode *prop = child->getChild( "prop" );
if ( prop != NULL ) {
r_n_prop = fgGetNode( prop->getStringValue(), true );
} else {
prop = child->getChild( "value" );
if ( prop != NULL ) {
r_n_value = prop->getDoubleValue();
}
}
prop = child->getChild( "scale" );
if ( prop != NULL ) {
r_scale = prop->getDoubleValue();
}
} else if ( cname == "output" ) {
int i = 0;
SGPropertyNode *prop;
while ( (prop = child->getChild("prop", i)) != NULL ) {
SGPropertyNode *tmp = fgGetNode( prop->getStringValue(), true );
output_list.push_back( tmp );
i++;
}
} else if ( cname == "config" ) {
SGPropertyNode *prop;
prop = child->getChild( "Kp" );
if ( prop != NULL ) {
Kp = prop->getDoubleValue();
proportional = true;
}
prop = child->getChild( "Ki" );
if ( prop != NULL ) {
Ki = prop->getDoubleValue();
integral = true;
}
prop = child->getChild( "u_min" );
if ( prop != NULL ) {
u_min = prop->getDoubleValue();
clamp = true;
}
prop = child->getChild( "u_max" );
if ( prop != NULL ) {
u_max = prop->getDoubleValue();
clamp = true;
}
} else {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Error in autopilot config logic" );
if ( name.length() ) {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Section = " << name );
}
}
}
}
void FGPISimpleController::update( double dt ) {
if (enable_prop != NULL && enable_prop->getStringValue() == enable_value) {
if ( !enabled ) {
// we have just been enabled, zero out int_sum
int_sum = 0.0;
}
enabled = true;
} else {
enabled = false;
}
if ( enabled ) {
if ( debug ) cout << "Updating " << name << endl;
double input = 0.0;
if ( input_prop != NULL ) {
input = input_prop->getDoubleValue() * y_scale;
}
double r_n = 0.0;
if ( r_n_prop != NULL ) {
r_n = r_n_prop->getDoubleValue() * r_scale;
} else {
r_n = r_n_value;
}
double error = r_n - input;
if ( debug ) cout << "input = " << input
<< " reference = " << r_n
<< " error = " << error
<< endl;
double prop_comp = 0.0;
double offset = 0.0;
if ( offset_prop != NULL ) {
offset = offset_prop->getDoubleValue();
if ( debug ) cout << "offset = " << offset << endl;
} else {
offset = offset_value;
}
if ( proportional ) {
prop_comp = error * Kp + offset;
}
if ( integral ) {
int_sum += error * Ki * dt;
} else {
int_sum = 0.0;
}
if ( debug ) cout << "prop_comp = " << prop_comp
<< " int_sum = " << int_sum << endl;
double output = prop_comp + int_sum;
if ( clamp ) {
if ( output < u_min ) {
output = u_min;
}
if ( output > u_max ) {
output = u_max;
}
}
if ( debug ) cout << "output = " << output << endl;
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output );
}
}
}
FGPredictor::FGPredictor ( SGPropertyNode *node ):
last_value ( 999999999.9 ),
average ( 0.0 ),
seconds( 0.0 ),
filter_gain( 0.0 ),
debug( false ),
ivalue( 0.0 )
{
int i;
for ( i = 0; i < node->nChildren(); ++i ) {
SGPropertyNode *child = node->getChild(i);
string cname = child->getName();
string cval = child->getStringValue();
if ( cname == "name" ) {
name = cval;
} else if ( cname == "debug" ) {
debug = child->getBoolValue();
} else if ( cname == "input" ) {
input_prop = fgGetNode( child->getStringValue(), true );
} else if ( cname == "seconds" ) {
seconds = child->getDoubleValue();
} else if ( cname == "filter-gain" ) {
filter_gain = child->getDoubleValue();
} else if ( cname == "output" ) {
SGPropertyNode *tmp = fgGetNode( child->getStringValue(), true );
output_list.push_back( tmp );
}
}
}
void FGPredictor::update( double dt ) {
/*
Simple moving average filter converts input value to predicted value "seconds".
Smoothing as described by Curt Olson:
gain would be valid in the range of 0 - 1.0
1.0 would mean no filtering.
0.0 would mean no input.
0.5 would mean (1 part past value + 1 part current value) / 2
0.1 would mean (9 parts past value + 1 part current value) / 10
0.25 would mean (3 parts past value + 1 part current value) / 4
*/
if ( input_prop != NULL ) {
ivalue = input_prop->getDoubleValue();
// no sense if there isn't an input :-)
enabled = true;
} else {
enabled = false;
}
if ( enabled ) {
// first time initialize average
if (last_value >= 999999999.0) {
last_value = ivalue;
}
if ( dt > 0.0 ) {
double current = (ivalue - last_value)/dt; // calculate current error change (per second)
if ( dt < 1.0 ) {
average = (1.0 - dt) * average + current * dt;
} else {
average = current;
}
// calculate output with filter gain adjustment
double output = ivalue + (1.0 - filter_gain) * (average * seconds) + filter_gain * (current * seconds);
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output );
}
}
last_value = ivalue;
}
}
FGDigitalFilter::FGDigitalFilter(SGPropertyNode *node)
{
samples = 1;
int i;
for ( i = 0; i < node->nChildren(); ++i ) {
SGPropertyNode *child = node->getChild(i);
string cname = child->getName();
string cval = child->getStringValue();
if ( cname == "name" ) {
name = cval;
} else if ( cname == "debug" ) {
debug = child->getBoolValue();
} else if ( cname == "type" ) {
if ( cval == "exponential" ) {
filterType = exponential;
} else if (cval == "double-exponential") {
filterType = doubleExponential;
} else if (cval == "moving-average") {
filterType = movingAverage;
} else if (cval == "noise-spike") {
filterType = noiseSpike;
}
} else if ( cname == "input" ) {
input_prop = fgGetNode( child->getStringValue(), true );
} else if ( cname == "filter-time" ) {
Tf = child->getDoubleValue();
} else if ( cname == "samples" ) {
samples = child->getIntValue();
} else if ( cname == "max-rate-of-change" ) {
rateOfChange = child->getDoubleValue();
} else if ( cname == "output" ) {
SGPropertyNode *tmp = fgGetNode( child->getStringValue(), true );
output_list.push_back( tmp );
}
}
output.resize(2, 0.0);
input.resize(samples + 1, 0.0);
}
void FGDigitalFilter::update(double dt)
{
if ( input_prop != NULL ) {
input.push_front(input_prop->getDoubleValue());
input.resize(samples + 1, 0.0);
// no sense if there isn't an input :-)
enabled = true;
} else {
enabled = false;
}
if ( enabled && dt > 0.0 ) {
/*
* Exponential filter
*
* Output[n] = alpha*Input[n] + (1-alpha)*Output[n-1]
*
*/
if (filterType == exponential)
{
double alpha = 1 / ((Tf/dt) + 1);
output.push_front(alpha * input[0] +
(1 - alpha) * output[0]);
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output[0] );
}
output.resize(1);
}
else if (filterType == doubleExponential)
{
double alpha = 1 / ((Tf/dt) + 1);
output.push_front(alpha * alpha * input[0] +
2 * (1 - alpha) * output[0] -
(1 - alpha) * (1 - alpha) * output[1]);
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output[0] );
}
output.resize(2);
}
else if (filterType == movingAverage)
{
output.push_front(output[0] +
(input[0] - input.back()) / samples);
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output[0] );
}
output.resize(1);
}
else if (filterType == noiseSpike)
{
double maxChange = rateOfChange * dt;
if ((output[0] - input[0]) > maxChange)
{
output.push_front(output[0] - maxChange);
}
else if ((output[0] - input[0]) < -maxChange)
{
output.push_front(output[0] + maxChange);
}
else if (fabs(input[0] - output[0]) <= maxChange)
{
output.push_front(input[0]);
}
unsigned int i;
for ( i = 0; i < output_list.size(); ++i ) {
output_list[i]->setDoubleValue( output[0] );
}
output.resize(1);
}
if (debug)
{
cout << "input:" << input[0]
<< "\toutput:" << output[0] << endl;
}
}
}
FGXMLAutopilot::FGXMLAutopilot() {
}
FGXMLAutopilot::~FGXMLAutopilot() {
}
void FGXMLAutopilot::init() {
config_props = fgGetNode( "/autopilot/new-config", true );
SGPropertyNode *path_n = fgGetNode("/sim/systems/autopilot/path");
if ( path_n ) {
SGPath config( globals->get_fg_root() );
config.append( path_n->getStringValue() );
SG_LOG( SG_ALL, SG_INFO, "Reading autopilot configuration from "
<< config.str() );
try {
readProperties( config.str(), config_props );
if ( ! build() ) {
SG_LOG( SG_ALL, SG_ALERT,
"Detected an internal inconsistency in the autopilot");
SG_LOG( SG_ALL, SG_ALERT,
" configuration. See earlier errors for" );
SG_LOG( SG_ALL, SG_ALERT,
" details.");
exit(-1);
}
} catch (const sg_exception& exc) {
SG_LOG( SG_ALL, SG_ALERT, "Failed to load autopilot configuration: "
<< config.str() );
}
} else {
SG_LOG( SG_ALL, SG_WARN,
"No autopilot configuration specified for this model!");
}
}
void FGXMLAutopilot::reinit() {
components.clear();
init();
build();
}
void FGXMLAutopilot::bind() {
}
void FGXMLAutopilot::unbind() {
}
bool FGXMLAutopilot::build() {
SGPropertyNode *node;
int i;
int count = config_props->nChildren();
for ( i = 0; i < count; ++i ) {
node = config_props->getChild(i);
string name = node->getName();
// cout << name << endl;
if ( name == "pid-controller" ) {
FGXMLAutoComponent *c = new FGPIDController( node );
components.push_back( c );
} else if ( name == "pi-simple-controller" ) {
FGXMLAutoComponent *c = new FGPISimpleController( node );
components.push_back( c );
} else if ( name == "predict-simple" ) {
FGXMLAutoComponent *c = new FGPredictor( node );
components.push_back( c );
} else if ( name == "filter" ) {
FGXMLAutoComponent *c = new FGDigitalFilter( node );
components.push_back( c );
} else {
SG_LOG( SG_ALL, SG_ALERT, "Unknown top level section: "
<< name );
return false;
}
}
return true;
}
/*
* Update helper values
*/
static void update_helper( double dt ) {
// Estimate speed in 5,10 seconds
static SGPropertyNode *vel = fgGetNode( "/velocities/airspeed-kt", true );
static SGPropertyNode *lookahead5
= fgGetNode( "/autopilot/internal/lookahead-5-sec-airspeed-kt", true );
static SGPropertyNode *lookahead10
= fgGetNode( "/autopilot/internal/lookahead-10-sec-airspeed-kt", true );
static double average = 0.0; // average/filtered prediction
static double v_last = 0.0; // last velocity
double v = vel->getDoubleValue();
double a = 0.0;
if ( dt > 0.0 ) {
a = (v - v_last) / dt;
if ( dt < 1.0 ) {
average = (1.0 - dt) * average + dt * a;
} else {
average = a;
}
lookahead5->setDoubleValue( v + average * 5.0 );
lookahead10->setDoubleValue( v + average * 10.0 );
v_last = v;
}
// Calculate heading bug error normalized to +/- 180.0 (based on
// DG indicated heading)
static SGPropertyNode *bug
= fgGetNode( "/autopilot/settings/heading-bug-deg", true );
static SGPropertyNode *ind_hdg
= fgGetNode( "/instrumentation/heading-indicator/indicated-heading-deg",
true );
static SGPropertyNode *ind_bug_error
= fgGetNode( "/autopilot/internal/heading-bug-error-deg", true );
double diff = bug->getDoubleValue() - ind_hdg->getDoubleValue();
if ( diff < -180.0 ) { diff += 360.0; }
if ( diff > 180.0 ) { diff -= 360.0; }
ind_bug_error->setDoubleValue( diff );
// Calculate heading bug error normalized to +/- 180.0 (based on
// actual/nodrift magnetic-heading, i.e. a DG slaved to magnetic
// compass.)
static SGPropertyNode *mag_hdg
= fgGetNode( "/orientation/heading-magnetic-deg", true );
static SGPropertyNode *fdm_bug_error
= fgGetNode( "/autopilot/internal/fdm-heading-bug-error-deg", true );
diff = bug->getDoubleValue() - mag_hdg->getDoubleValue();
if ( diff < -180.0 ) { diff += 360.0; }
if ( diff > 180.0 ) { diff -= 360.0; }
fdm_bug_error->setDoubleValue( diff );
// Calculate true heading error normalized to +/- 180.0
static SGPropertyNode *target_true
= fgGetNode( "/autopilot/settings/true-heading-deg", true );
static SGPropertyNode *true_hdg
= fgGetNode( "/orientation/heading-deg", true );
static SGPropertyNode *true_track
= fgGetNode( "/instrumentation/gps/indicated-track-true-deg", true );
static SGPropertyNode *true_error
= fgGetNode( "/autopilot/internal/true-heading-error-deg", true );
diff = target_true->getDoubleValue() - true_hdg->getDoubleValue();
if ( diff < -180.0 ) { diff += 360.0; }
if ( diff > 180.0 ) { diff -= 360.0; }
true_error->setDoubleValue( diff );
// Calculate nav1 target heading error normalized to +/- 180.0
static SGPropertyNode *target_nav1
= fgGetNode( "/instrumentation/nav[0]/radials/target-auto-hdg-deg", true );
static SGPropertyNode *true_nav1
= fgGetNode( "/autopilot/internal/nav1-heading-error-deg", true );
static SGPropertyNode *true_track_nav1
= fgGetNode( "/autopilot/internal/nav1-track-error-deg", true );
diff = target_nav1->getDoubleValue() - true_hdg->getDoubleValue();
if ( diff < -180.0 ) { diff += 360.0; }
if ( diff > 180.0 ) { diff -= 360.0; }
true_nav1->setDoubleValue( diff );
diff = target_nav1->getDoubleValue() - true_track->getDoubleValue();
if ( diff < -180.0 ) { diff += 360.0; }
if ( diff > 180.0 ) { diff -= 360.0; }
true_track_nav1->setDoubleValue( diff );
// Calculate nav1 selected course error normalized to +/- 180.0
// (based on DG indicated heading)
static SGPropertyNode *nav1_course_error
= fgGetNode( "/autopilot/internal/nav1-course-error", true );
static SGPropertyNode *nav1_selected_course
= fgGetNode( "/instrumentation/nav[0]/radials/selected-deg", true );
diff = nav1_selected_course->getDoubleValue() - ind_hdg->getDoubleValue();
// if ( diff < -180.0 ) { diff += 360.0; }
// if ( diff > 180.0 ) { diff -= 360.0; }
SG_NORMALIZE_RANGE( diff, -180.0, 180.0 );
nav1_course_error->setDoubleValue( diff );
// Calculate vertical speed in fpm
static SGPropertyNode *vs_fps
= fgGetNode( "/velocities/vertical-speed-fps", true );
static SGPropertyNode *vs_fpm
= fgGetNode( "/autopilot/internal/vert-speed-fpm", true );
vs_fpm->setDoubleValue( vs_fps->getDoubleValue() * 60.0 );
// Calculate static port pressure rate in [inhg/s].
// Used to determine vertical speed.
static SGPropertyNode *static_pressure
= fgGetNode( "/systems/static[0]/pressure-inhg", true );
static SGPropertyNode *pressure_rate
= fgGetNode( "/autopilot/internal/pressure-rate", true );
static double last_static_pressure = 0.0;
if ( dt > 0.0 ) {
double current_static_pressure = static_pressure->getDoubleValue();
double current_pressure_rate =
( current_static_pressure - last_static_pressure ) / dt;
pressure_rate->setDoubleValue(current_pressure_rate);
last_static_pressure = current_static_pressure;
}
}
/*
* Update the list of autopilot components
*/
void FGXMLAutopilot::update( double dt ) {
update_helper( dt );
unsigned int i;
for ( i = 0; i < components.size(); ++i ) {
components[i]->update( dt );
}
}
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