From eb6b28f5074654f25fb9118160a70f5a114f6970 Mon Sep 17 00:00:00 2001
From: mfranz <mfranz>
Date: Mon, 23 Oct 2006 21:58:28 +0000
Subject: [PATCH] Vivian MEAZZA: Directional Gyro (DG) compass & electrically
 powered master                reference gyro

---
 src/Instrumentation/Makefile.am              |   2 +
 src/Instrumentation/heading_indicator_dg.cxx | 155 ++++++++++++
 src/Instrumentation/heading_indicator_dg.hxx |  64 +++++
 src/Instrumentation/mrg.cxx                  | 247 +++++++++++++++++++
 src/Instrumentation/mrg.hxx                  |  96 +++++++
 5 files changed, 564 insertions(+)
 create mode 100644 src/Instrumentation/heading_indicator_dg.cxx
 create mode 100644 src/Instrumentation/heading_indicator_dg.hxx
 create mode 100644 src/Instrumentation/mrg.cxx
 create mode 100644 src/Instrumentation/mrg.hxx

diff --git a/src/Instrumentation/Makefile.am b/src/Instrumentation/Makefile.am
index f59e18db7..a99087364 100644
--- a/src/Instrumentation/Makefile.am
+++ b/src/Instrumentation/Makefile.am
@@ -17,10 +17,12 @@ libInstrumentation_a_SOURCES = \
         gyro.cxx gyro.hxx \
         heading_indicator.cxx heading_indicator.hxx \
         heading_indicator_fg.cxx heading_indicator_fg.hxx \
+	heading_indicator_dg.cxx heading_indicator_dg.hxx \
 	kr_87.hxx kr_87.cxx \
 	kt_70.cxx kt_70.hxx \
         mag_compass.cxx mag_compass.hxx \
         marker_beacon.cxx marker_beacon.hxx \
+	mrg.cxx mrg.hxx\
         navradio.cxx navradio.hxx \
         slip_skid_ball.cxx slip_skid_ball.hxx \
 	transponder.cxx transponder.hxx \
diff --git a/src/Instrumentation/heading_indicator_dg.cxx b/src/Instrumentation/heading_indicator_dg.cxx
new file mode 100644
index 000000000..eb8726c89
--- /dev/null
+++ b/src/Instrumentation/heading_indicator_dg.cxx
@@ -0,0 +1,155 @@
+// heading_indicator_dg.cxx - a Directional Gyro (DG) compass.
+// Based on the vacuum driven Heading Indicator Written by David Megginson, 
+// started 2002.
+//
+// Written by Vivian Meazza, started 2005.
+//
+// This file is in the Public Domain and comes with no warranty.
+
+#include <simgear/compiler.h>
+#include STL_IOSTREAM
+#include STL_STRING
+#include <sstream>
+
+#include <Main/fg_props.hxx>
+#include <Main/util.hxx>
+
+#include "heading_indicator_dg.hxx"
+
+
+HeadingIndicatorDG::HeadingIndicatorDG ( SGPropertyNode *node ) :
+    name("heading-indicator-dg"),
+    num(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 == "number" ) {
+            num = child->getIntValue();
+        } else {
+            SG_LOG( SG_INSTR, SG_WARN, "Error in DG heading-indicator config logic" );
+            if ( name.length() ) {
+                SG_LOG( SG_INSTR, SG_WARN, "Section = " << name );
+            }
+        }
+    }
+}
+
+HeadingIndicatorDG::HeadingIndicatorDG ()
+{
+}
+
+HeadingIndicatorDG::~HeadingIndicatorDG ()
+{
+}
+
+void
+HeadingIndicatorDG::init ()
+{
+    string branch;
+    branch = "/instrumentation/" + name;
+
+    _heading_in_node = fgGetNode("/orientation/heading-deg", true);
+    SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
+    _offset_node = node->getChild("offset-deg", 0, true);
+    _serviceable_node = node->getChild("serviceable", 0, true);
+    _error_node = node->getChild("heading-bug-error-deg", 0, true);
+    _nav1_error_node = node->getChild("nav1-course-error-deg", 0, true);
+    _heading_out_node = node->getChild("indicated-heading-deg", 0, true);
+    _last_heading_deg = (_heading_in_node->getDoubleValue() +
+                         _offset_node->getDoubleValue());
+    _electrical_node = fgGetNode("/systems/electrical/outputs/DG", true);
+}
+
+void
+HeadingIndicatorDG::bind ()
+{
+    std::ostringstream temp;
+    string branch;
+    temp << num;
+    branch = "/instrumentation/" + name + "[" + temp.str() + "]";
+
+    fgTie((branch + "/serviceable").c_str(),
+          &_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
+    fgTie((branch + "/spin").c_str(),
+          &_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
+}
+
+void
+HeadingIndicatorDG::unbind ()
+{
+    std::ostringstream temp;
+    string branch;
+    temp << num;
+    branch = "/instrumentation/" + name + "[" + temp.str() + "]";
+
+    fgUntie((branch + "/serviceable").c_str());
+    fgUntie((branch + "/spin").c_str());
+}
+
+void
+HeadingIndicatorDG::update (double dt)
+{
+                                // Get the spin from the gyro
+    _gyro.set_power_norm(_electrical_node->getDoubleValue());
+
+    _gyro.update(dt);
+    double spin = _gyro.get_spin_norm();
+
+                                // No time-based precession	for a flux gate compass
+                                // No magvar
+    double offset = 0;
+
+                                // 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);
+
+                                 // calculate the difference between the indicacted heading
+                                 // and the selected heading for use with an autopilot
+    static SGPropertyNode *bnode
+        = fgGetNode( "/autopilot/settings/heading-bug-deg", false );
+    if ( bnode ) {
+        double diff = bnode->getDoubleValue() - heading;
+        if ( diff < -180.0 ) { diff += 360.0; }
+        if ( diff > 180.0 ) { diff -= 360.0; }
+        _error_node->setDoubleValue( diff );
+    }
+                                 // calculate the difference between the indicated heading
+                                 // and the selected nav1 radial for use with an autopilot
+    SGPropertyNode *nnode
+        = fgGetNode( "/instrumentation/nav/radials/selected-deg", false );
+    if ( nnode ) {
+        double diff = nnode->getDoubleValue() - heading;
+        if ( diff < -180.0 ) { diff += 360.0; }
+        if ( diff > 180.0 ) { diff -= 360.0; }
+        _nav1_error_node->setDoubleValue( diff );
+    }
+}
+
+// end of heading_indicator_fg.cxx
diff --git a/src/Instrumentation/heading_indicator_dg.hxx b/src/Instrumentation/heading_indicator_dg.hxx
new file mode 100644
index 000000000..89c22f3b9
--- /dev/null
+++ b/src/Instrumentation/heading_indicator_dg.hxx
@@ -0,0 +1,64 @@
+// heading_indicator.hxx - a vacuum-powered heading indicator.
+// Written by David Megginson, started 2002.
+//
+// This file is in the Public Domain and comes with no warranty.
+
+
+#ifndef __INSTRUMENTS_HEADING_INDICATOR_ELEC_HXX
+#define __INSTRUMENTS_HEADING_INDICATOR_ELEC_HXX 1
+
+
+#include <simgear/props/props.hxx>
+#include <simgear/structure/subsystem_mgr.hxx>
+
+#include "gyro.hxx"
+
+
+/**
+ * Model an electrically-powered heading indicator.
+ *
+ * Input properties:
+ *
+ * /instrumentation/"name"/serviceable
+ * /instrumentation/"name"/spin
+ * /instrumentation/"name"/offset-deg
+ * /orientation/heading-deg
+ * /systems/electrical/outputs/DG
+ *
+ * Output properties:
+ *
+ * /instrumentation/"name"/indicated-heading-deg
+ */
+class HeadingIndicatorDG : public SGSubsystem
+{
+
+public:
+
+    HeadingIndicatorDG ( SGPropertyNode *node );
+    HeadingIndicatorDG ();
+    virtual ~HeadingIndicatorDG ();
+
+    virtual void init ();
+    virtual void bind ();
+    virtual void unbind ();
+    virtual void update (double dt);
+
+private:
+
+    Gyro _gyro;
+    double _last_heading_deg;
+
+    string name;
+    int num;
+    //string vacuum_system;
+
+    SGPropertyNode_ptr _offset_node;
+    SGPropertyNode_ptr _heading_in_node;
+    SGPropertyNode_ptr _serviceable_node;
+    SGPropertyNode_ptr _heading_out_node;
+    SGPropertyNode_ptr _electrical_node;
+    SGPropertyNode_ptr _error_node;
+    SGPropertyNode_ptr _nav1_error_node;
+};
+
+#endif // __INSTRUMENTS_HEADING_INDICATOR_ELEC_HXX
diff --git a/src/Instrumentation/mrg.cxx b/src/Instrumentation/mrg.cxx
new file mode 100644
index 000000000..918160ae5
--- /dev/null
+++ b/src/Instrumentation/mrg.cxx
@@ -0,0 +1,247 @@
+// MRG.cxx - an electrcally powered master reference gyro.
+// Written by Vivian Meazza based on wrok by David Megginson, started 2006.
+//
+// This file is in the Public Domain and comes with no warranty.
+
+// TODO:
+// - better spin-up
+
+#include <simgear/compiler.h>
+
+#include STL_IOSTREAM
+#include STL_STRING
+#include <sstream>
+#include <math.h>	// fabs()
+
+#include <Main/fg_props.hxx>
+#include <Main/util.hxx>
+
+#include "mrg.hxx"
+
+
+MasterReferenceGyro::MasterReferenceGyro ( SGPropertyNode *node ) :
+	name("master-reference-gyro"),
+	num(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 == "number" ) {
+			num = (int) child->getDoubleValue();
+		} else {
+			SG_LOG( SG_INSTR, SG_WARN, "Error in mrg config logic" );
+			if ( name.length() ) {
+				SG_LOG( SG_INSTR, SG_WARN, "Section = " << name );
+			}
+		}
+	}
+}
+
+MasterReferenceGyro::MasterReferenceGyro ()
+{
+}
+
+MasterReferenceGyro::~MasterReferenceGyro ()
+{
+}
+
+void
+MasterReferenceGyro::init ()
+{
+	_last_hdg = 0;
+	_last_roll = 0;
+	_last_pitch = 0;
+	_indicated_hdg = 0;
+	_indicated_roll = 0;
+	_indicated_pitch = 0;
+	_indicated_hdg_rate = 0;
+	_indicated_roll_rate = 0;
+	_indicated_pitch_rate = 0;
+	
+	string branch;
+	branch = "/instrumentation/" + name;
+
+	_pitch_in_node = fgGetNode("/orientation/pitch-deg", true);
+	_roll_in_node = fgGetNode("/orientation/roll-deg", true);
+	_hdg_in_node = fgGetNode("/orientation/heading-deg", true);
+	_pitch_rate_node = fgGetNode("/orientation/pitch-rate-degps", true);
+	_roll_rate_node = fgGetNode("/orientation/roll-rate-degps", true);
+	_yaw_rate_node = fgGetNode("/orientation/yaw-rate-degps", true);
+	_g_in_node =   fgGetNode("/accelerations/pilot-g-damped", true);
+	_electrical_node = fgGetNode("/systems/electrical/outputs/MRG", true);
+	
+	SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
+	_off_node = node->getChild("off-flag", 0, true);
+	_pitch_out_node = node->getChild("indicated-pitch-deg", 0, true);
+	_roll_out_node = node->getChild("indicated-roll-deg", 0, true);
+	_hdg_out_node = node->getChild("indicated-hdg-deg", 0, true);
+	_pitch_rate_out_node = node->getChild("indicated-pitch-rate-degps", 0, true);
+	_roll_rate_out_node = node->getChild("indicated-roll-rate-degps", 0, true);
+	_hdg_rate_out_node = node->getChild("indicated-hdg-rate-degps", 0, true);
+	_responsiveness_node = node->getChild("responsiveness", 0, true);
+	_error_out_node = node->getChild("heading-error-deg", 0, true);
+
+	_electrical_node->setDoubleValue(0);
+	_responsiveness_node->setDoubleValue(0.75);
+	_off_node->setBoolValue(false);
+}
+
+void
+MasterReferenceGyro::bind ()
+{
+	std::ostringstream temp;
+	string branch;
+	temp << num;
+	branch = "/instrumentation/" + name + "[" + temp.str() + "]";
+
+	fgTie((branch + "/serviceable").c_str(),
+		&_gyro, &Gyro::is_serviceable, &Gyro::set_serviceable);
+	fgTie((branch + "/spin").c_str(),
+		&_gyro, &Gyro::get_spin_norm, &Gyro::set_spin_norm);
+}
+
+void
+MasterReferenceGyro::unbind ()
+{
+	std::ostringstream temp;
+	string branch;
+	temp << num;
+	branch = "/instrumentation/" + name + "[" + temp.str() + "]";
+
+	fgUntie((branch + "/serviceable").c_str());
+	fgUntie((branch + "/spin").c_str());
+}
+
+void
+MasterReferenceGyro::update (double dt)
+{
+	double indicated_roll = 0;
+	double indicated_pitch = 0;
+	double indicated_hdg = 0;
+	double indicated_roll_rate = 0;
+	double indicated_pitch_rate = 0;
+	double indicated_hdg_rate = 0;
+
+	// Get the spin from the gyro
+	_gyro.set_power_norm( _electrical_node->getDoubleValue()/24 );
+	_gyro.update(dt);
+	double spin = _gyro.get_spin_norm();
+	
+	// set the "off-flag"
+	if ( _electrical_node->getDoubleValue() == 0 ) {
+		_off_node->setBoolValue(true);
+	} else if ( spin == 1 ) {
+		_off_node->setBoolValue(false);
+	} else {
+		_off_node->setBoolValue(true);
+	}
+
+	// Get the input values
+	double roll = _roll_in_node->getDoubleValue();
+	double pitch = _pitch_in_node->getDoubleValue();
+	double hdg = _hdg_in_node->getDoubleValue();
+	double roll_rate = _yaw_rate_node->getDoubleValue();
+	double pitch_rate = _yaw_rate_node->getDoubleValue();
+	double yaw_rate = _yaw_rate_node->getDoubleValue();
+
+	//modulate the input by the spin rate
+	double responsiveness = spin * spin * spin * spin * spin * spin;
+	roll = fgGetLowPass( _last_roll, roll, responsiveness );
+	pitch = fgGetLowPass( _last_pitch , pitch, responsiveness );
+	hdg = fgGetLowPass( _last_hdg , hdg, responsiveness );
+
+	//but we need to filter the hdg and yaw_rate as well - yuk!
+	responsiveness = 0.1 / (spin * spin * spin * spin * spin * spin);
+	yaw_rate = fgGetLowPass( _last_yaw_rate , yaw_rate, responsiveness );
+
+	// store the new values
+	_last_roll = roll;
+	_last_pitch = pitch;
+	_last_hdg = hdg;
+	_last_roll_rate = roll_rate;
+	_last_pitch_rate = pitch_rate;
+	_last_yaw_rate = yaw_rate;
+
+	//the gyro only erects inside limits
+	if ( abs ( yaw_rate ) <= 5
+			&& (_g_in_node->getDoubleValue() <= 1.5
+			|| _g_in_node->getDoubleValue() >= -0.5) ) {
+		indicated_roll = _last_roll;
+		indicated_pitch = _last_pitch;
+		indicated_hdg = _last_hdg;
+		indicated_roll_rate = _last_roll_rate;
+		indicated_pitch_rate = _last_pitch_rate;
+		indicated_hdg_rate = _last_yaw_rate;
+	} else {
+		indicated_roll_rate = 0;
+		indicated_pitch_rate = 0;
+		indicated_hdg_rate = 0;
+	}
+
+	// calculate the difference between the indicated heading
+	// and the selected heading for use with an autopilot
+	static SGPropertyNode *bnode
+		= fgGetNode( "autopilot/settings/target-heading-deg", false );
+
+	if ( bnode ) {
+		double diff = bnode->getDoubleValue() - indicated_hdg;
+		if ( diff < -180.0 ) { diff += 360.0; }
+		if ( diff > 180.0 ) { diff -= 360.0; }
+		_error_out_node->setDoubleValue( diff );
+	}
+	//cout << "autopilot input " << bnode->getDoubleValue() << "output " << _error_out_node->getDoubleValue()<<endl ;
+	//smooth the output
+	double factor = _responsiveness_node->getDoubleValue() * dt;
+
+	indicated_roll = fgGetLowPass( _indicated_roll, indicated_roll, factor );
+	indicated_pitch = fgGetLowPass( _indicated_pitch , indicated_pitch, factor );
+	indicated_hdg = fgGetLowPass( _indicated_hdg , indicated_hdg, factor );
+
+	indicated_roll_rate = fgGetLowPass( _indicated_roll_rate, indicated_roll_rate, factor );
+	indicated_pitch_rate = fgGetLowPass( _indicated_pitch_rate , indicated_pitch_rate, factor );
+	indicated_hdg_rate = fgGetLowPass( _indicated_hdg_rate , indicated_hdg_rate, factor );
+
+	// store the new values
+	_indicated_roll = indicated_roll;
+	_indicated_pitch = indicated_pitch;
+	_indicated_hdg = indicated_hdg;
+
+	_indicated_roll_rate = indicated_roll_rate;
+	_indicated_pitch_rate = indicated_pitch_rate;
+	_indicated_hdg_rate = indicated_hdg_rate;
+
+	// add in a gyro underspin "error" if gyro is spinning too slowly
+	const double spin_thresh = 0.8;
+	const double max_roll_error = 40.0;
+	const double max_pitch_error = 12.0;
+	const double max_hdg_error = 140.0;
+	double roll_error;
+	double pitch_error;
+	double hdg_error;
+
+	if ( spin <= spin_thresh ) {
+		double roll_error_factor	= ( spin_thresh - spin ) / spin_thresh;
+		double pitch_error_factor	= ( spin_thresh - spin ) / spin_thresh;
+		double hdg_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;
+		hdg_error	= hdg_error_factor * hdg_error_factor * max_hdg_error;
+	} else {
+		roll_error = 0.0;
+		pitch_error = 0.0;
+		hdg_error = 0.0;
+	}
+
+	_roll_out_node->setDoubleValue( _indicated_roll + roll_error );
+	_pitch_out_node->setDoubleValue( _indicated_pitch + pitch_error );
+	_hdg_out_node->setDoubleValue( _indicated_hdg + hdg_error );
+	_pitch_rate_out_node ->setDoubleValue( _indicated_pitch_rate );
+	_roll_rate_out_node ->setDoubleValue( _indicated_roll_rate );
+	_hdg_rate_out_node ->setDoubleValue( _indicated_hdg_rate );
+}
+
+// end of mrg.cxx
diff --git a/src/Instrumentation/mrg.hxx b/src/Instrumentation/mrg.hxx
new file mode 100644
index 000000000..b10f653ce
--- /dev/null
+++ b/src/Instrumentation/mrg.hxx
@@ -0,0 +1,96 @@
+// attitude_indicator.hxx - a vacuum-powered attitude indicator.
+// Written by David Megginson, started 2002.
+//
+// This file is in the Public Domain and comes with no warranty.
+
+
+#ifndef __INSTRUMENTS_MRG_HXX
+#define __INSTRUMENTS_MRG_HXX 1
+
+
+#include <simgear/props/props.hxx>
+#include <simgear/structure/subsystem_mgr.hxx>
+
+#include "gyro.hxx"
+
+
+/**
+ * Model a vacuum-powered attitude indicator.
+ *
+ * Input properties:
+ *
+ * /instrumentation/"name"/config/tumble-flag
+ * /instrumentation/"name"/serviceable
+ * /instrumentation/"name"/caged-flag
+ * /instrumentation/"name"/tumble-norm
+ * /orientation/pitch-deg
+ * /orientation/roll-deg
+ * "vacuum-system"/suction-inhg
+ *
+ * Output properties:
+ *
+ * /instrumentation/"name"/indicated-pitch-deg
+ * /instrumentation/"name"/indicated-roll-deg
+ * /instrumentation/"name"/tumble-norm
+ */
+
+class MasterReferenceGyro : public SGSubsystem
+{
+
+public:
+
+    MasterReferenceGyro ( SGPropertyNode *node );
+    MasterReferenceGyro ();
+    virtual ~MasterReferenceGyro ();
+
+    virtual void init ();
+    virtual void bind ();
+    virtual void unbind ();
+    virtual void update (double dt);
+
+private:
+
+    string name;
+    int num;
+
+    double _last_roll;
+    double _last_pitch;
+    double _last_hdg;
+    double _indicated_roll;
+    double _indicated_pitch;
+    double _indicated_hdg;
+    double _indicated_pitch_rate;
+    double _indicated_roll_rate;
+    double _indicated_hdg_rate;
+    double _last_roll_rate;
+    double _last_pitch_rate;
+    double _last_yaw_rate;
+
+    Gyro _gyro;
+
+    SGPropertyNode_ptr _tumble_flag_node;
+    SGPropertyNode_ptr _caged_node;
+    SGPropertyNode_ptr _off_node;
+    SGPropertyNode_ptr _tumble_node;
+    SGPropertyNode_ptr _pitch_in_node;
+    SGPropertyNode_ptr _roll_in_node;
+    SGPropertyNode_ptr _hdg_in_node;
+    SGPropertyNode_ptr _g_in_node;
+    SGPropertyNode_ptr _electrical_node;
+    SGPropertyNode_ptr _pitch_int_node;
+    SGPropertyNode_ptr _roll_int_node;
+    SGPropertyNode_ptr _hdg_int_node;
+    SGPropertyNode_ptr _pitch_out_node;
+    SGPropertyNode_ptr _roll_out_node;
+    SGPropertyNode_ptr _hdg_out_node;
+    SGPropertyNode_ptr _pitch_rate_out_node;
+    SGPropertyNode_ptr _roll_rate_out_node;
+    SGPropertyNode_ptr _hdg_rate_out_node;
+    SGPropertyNode_ptr _error_out_node;
+    SGPropertyNode_ptr _yaw_rate_node;
+    SGPropertyNode_ptr _roll_rate_node;
+    SGPropertyNode_ptr _pitch_rate_node;
+    SGPropertyNode_ptr _responsiveness_node;
+};
+
+#endif // __INSTRUMENTS_MRG_HXX
-- 
2.39.5