93 lines
2.8 KiB
C++
93 lines
2.8 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 "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 ()
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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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_offset_node =
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fgGetNode("/instrumentation/heading-indicator/offset-deg", true);
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_heading_in_node = fgGetNode("/orientation/heading-deg", true);
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_suction_node = fgGetNode("/systems/vacuum[0]/suction-inhg", true);
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_heading_out_node =
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fgGetNode("/instrumentation/heading-indicator/indicated-heading-deg",
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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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fgTie("/instrumentation/heading-indicator/serviceable",
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&_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
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fgTie("/instrumentation/heading-indicator/spin",
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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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fgUntie("/instrumentation/heading-indicator/serviceable");
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fgUntie("/instrumentation/heading-indicator/spin");
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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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while (offset < -360)
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offset += 360;
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while (offset > 360)
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offset -= 360;
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_offset_node->setDoubleValue(offset);
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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 = 0.01 / (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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while (heading < 0)
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heading += 360;
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while (heading > 360)
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heading -= 360;
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_heading_out_node->setDoubleValue(heading);
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}
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// end of heading_indicator.cxx
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