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flightgear/src/Instrumentation/heading_indicator.cxx
ehofman f614545fc5 Roy Vegard Ovesen:
Instrumentation and systems are now configureable from xml files. The two
generic configurations generic-systems.xml and generic-instrumentation.xml
configures the systems and instrumentation as it was hardcoded. You can
override the generic configurations in a similar way as you override the
autopilot configuration.
2004-10-16 12:37:39 +00:00

129 lines
3.8 KiB
C++

// heading_indicator.cxx - a vacuum-powered heading indicator.
// Written by David Megginson, started 2002.
//
// This file is in the Public Domain and comes with no warranty.
#include "heading_indicator.hxx"
#include <Main/fg_props.hxx>
#include <Main/util.hxx>
HeadingIndicator::HeadingIndicator ( SGPropertyNode *node )
:
name("heading-indicator"),
num(0),
vacuum_system("/systems/vacuum")
{
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 == "number" ) {
num = child->getIntValue();
} else if ( cname == "vacuum-system" ) {
vacuum_system = cval;
} else {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Error in heading-indicator config logic" );
if ( name.length() ) {
SG_LOG( SG_AUTOPILOT, SG_WARN, "Section = " << name );
}
}
}
}
HeadingIndicator::HeadingIndicator ()
{
}
HeadingIndicator::~HeadingIndicator ()
{
}
void
HeadingIndicator::init ()
{
string branch;
branch = "/instrumentation/" + name;
vacuum_system += "/suction-inhg";
SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
_offset_node = node->getChild("offset-deg", 0, true);
_heading_in_node = fgGetNode("/orientation/heading-deg", true);
_suction_node = fgGetNode(vacuum_system.c_str(), true);
_heading_out_node = node->getChild("indicated-heading-deg", 0, true);
_last_heading_deg = (_heading_in_node->getDoubleValue() +
_offset_node->getDoubleValue());
//_serviceable_node->setBoolValue(true);
}
void
HeadingIndicator::bind ()
{
string branch;
branch = "/instrumentation/" + name + "/serviceable";
fgTie(branch.c_str(),
&_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
branch = "/instrumentation/" + name + "/spin";
fgTie(branch.c_str(),
&_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
}
void
HeadingIndicator::unbind ()
{
string branch;
branch = "/instrumentation/" + name + "/serviceable";
fgUntie(branch.c_str());
branch = "/instrumentation/" + name + "/spin";
fgUntie(branch.c_str());
}
void
HeadingIndicator::update (double dt)
{
// Get the spin from the gyro
_gyro.set_power_norm(_suction_node->getDoubleValue()/5.0);
_gyro.update(dt);
double spin = _gyro.get_spin_norm();
// Next, calculate time-based precession
double offset = _offset_node->getDoubleValue();
offset -= dt * (0.25 / 60.0); // 360deg/day
while (offset < -360)
offset += 360;
while (offset > 360)
offset -= 360;
_offset_node->setDoubleValue(offset);
// TODO: movement-induced error
// Next, calculate the indicated heading,
// introducing errors.
double factor = 0.01 / (spin * spin * spin * spin * spin * spin);
double heading = _heading_in_node->getDoubleValue();
// Now, we have to get the current
// heading and the last heading into
// the same range.
while ((heading - _last_heading_deg) > 180)
_last_heading_deg += 360;
while ((heading - _last_heading_deg) < -180)
_last_heading_deg -= 360;
heading = fgGetLowPass(_last_heading_deg, heading, dt/factor);
_last_heading_deg = heading;
heading += offset;
while (heading < 0)
heading += 360;
while (heading > 360)
heading -= 360;
_heading_out_node->setDoubleValue(heading);
}
// end of heading_indicator.cxx