116 lines
3.6 KiB
C++
116 lines
3.6 KiB
C++
// heading_indicator.cxx - a vacuum-powered heading indicator.
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// Written by David Megginson, started 2002.
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//
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// This file is in the Public Domain and comes with no warranty.
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#include <simgear/compiler.h>
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#include <simgear/sg_inlines.h>
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#include <iostream>
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#include <string>
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#include <sstream>
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#include "heading_indicator.hxx"
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#include <Main/fg_props.hxx>
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#include <Main/util.hxx>
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HeadingIndicator::HeadingIndicator ( SGPropertyNode *node )
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:
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_name(node->getStringValue("name", "heading-indicator")),
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_num(node->getIntValue("number", 0)),
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_suction(node->getStringValue("suction", "/systems/vacuum/suction-inhg"))
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{
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}
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HeadingIndicator::~HeadingIndicator ()
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{
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}
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void
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HeadingIndicator::init ()
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{
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string branch;
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branch = "/instrumentation/" + _name;
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SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
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_offset_node = node->getChild("offset-deg", 0, true);
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_heading_in_node = fgGetNode("/orientation/heading-deg", true);
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_suction_node = fgGetNode(_suction.c_str(), true);
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_heading_out_node = node->getChild("indicated-heading-deg", 0, true);
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_heading_bug_error_node = node->getChild("heading-bug-error-deg", 0, true);
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_heading_bug_node = node->getChild("heading-bug-deg", 0, true);
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_last_heading_deg = (_heading_in_node->getDoubleValue() +
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_offset_node->getDoubleValue());
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}
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void
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HeadingIndicator::bind ()
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{
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std::ostringstream temp;
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string branch;
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temp << _num;
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branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
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fgTie((branch + "/serviceable").c_str(),
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&_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
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fgTie((branch + "/spin").c_str(),
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&_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
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}
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void
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HeadingIndicator::unbind ()
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{
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std::ostringstream temp;
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string branch;
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temp << _num;
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branch = "/instrumentation/" + _name + "[" + temp.str() + "]";
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fgUntie((branch + "/serviceable").c_str());
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fgUntie((branch + "/spin").c_str());
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}
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void
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HeadingIndicator::update (double dt)
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{
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// Get the spin from the gyro
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_gyro.set_power_norm(_suction_node->getDoubleValue()/5.0);
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_gyro.update(dt);
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double spin = _gyro.get_spin_norm();
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// Next, calculate time-based precession
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double offset = _offset_node->getDoubleValue();
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offset -= dt * (0.25 / 60.0); // 360deg/day
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SG_NORMALIZE_RANGE(offset, -360.0, 360.0);
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// TODO: movement-induced error
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// Next, calculate the indicated heading,
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// introducing errors.
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double factor = 100 * (spin * spin * spin * spin * spin * spin);
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double heading = _heading_in_node->getDoubleValue();
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// Now, we have to get the current
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// heading and the last heading into
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// the same range.
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while ((heading - _last_heading_deg) > 180)
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_last_heading_deg += 360;
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while ((heading - _last_heading_deg) < -180)
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_last_heading_deg -= 360;
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heading = fgGetLowPass(_last_heading_deg, heading, dt * factor);
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_last_heading_deg = heading;
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heading += offset;
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SG_NORMALIZE_RANGE(heading, 0.0, 360.0);
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_heading_out_node->setDoubleValue(heading);
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// Calculate heading bug error normalized to +/- 180.0
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double heading_bug = _heading_bug_node->getDoubleValue();
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double diff = heading_bug - heading;
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SG_NORMALIZE_RANGE(diff, -180.0, 180.0);
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_heading_bug_error_node->setDoubleValue( diff );
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}
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// end of heading_indicator.cxx
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