// altimeter.cxx - an altimeter tied to the static port.
// Written by David Megginson, started 2002.
+// Modified by John Denker in 2007 to use a two layer atmosphere
+// model in src/Environment/atmosphere.?xx
//
// This file is in the Public Domain and comes with no warranty.
+// Example invocation, in the instrumentation.xml file:
+// <altimeter>
+// <name>encoder</name>
+// <number>0</number>
+// <static-pressure>/systems/static/pressure-inhg</static-pressure>
+// <quantum>10</quantum>
+// <tau>0</tau>
+// </altimeter>
+// Note non-default name, quantum, and tau values.
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
#include <simgear/math/interpolater.hxx>
+#include <simgear/math/SGMath.hxx>
-#include "altimeter.hxx"
#include <Main/fg_props.hxx>
#include <Main/util.hxx>
+#include <Environment/atmosphere.hxx>
+#include "altimeter.hxx"
-// A higher number means more responsive
-#define RESPONSIVENESS 10.0
-
-
-// Altitude based on pressure difference from sea level.
-// pressure difference inHG, altitude ft
-static double altitude_data[][2] = {
- { -8.41, -8858.27 },
- { 0.00, 0.00 },
- { 3.05, 2952.76 },
- { 5.86, 5905.51 },
- { 8.41, 8858.27 },
- { 10.74, 11811.02 },
- { 12.87, 14763.78 },
- { 14.78, 17716.54 },
- { 16.55, 20669.29 },
- { 18.13, 23622.05 },
- { 19.62, 26574.80 },
- { 20.82, 29527.56 },
- { 21.96, 32480.31 },
- { 23.01, 35433.07 },
- { 23.91, 38385.83 },
- { 24.71, 41338.58 },
- { 25.40, 44291.34 },
- { 26.00, 47244.09 },
- { 26.51, 50196.85 },
- { 26.96, 53149.61 },
- { 27.35, 56102.36 },
- { 27.68, 59055.12 },
- { 27.98, 62007.87 },
- { 29.62, 100000.00 }, // just to fill it in
- { -1, -1 }
-};
-
-
-Altimeter::Altimeter ( SGPropertyNode *node )
- : _altitude_table(new SGInterpTable),
- name("altimeter"),
- num(0),
- static_port("/systems/static")
-{
- int i;
- for (i = 0; altitude_data[i][0] != -1; i++)
- _altitude_table->addEntry(altitude_data[i][0], altitude_data[i][1]);
-
- 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 == "static-port" ) {
- static_port = cval;
- } else {
- SG_LOG( SG_INSTR, SG_WARN, "Error in altimeter config logic" );
- if ( name.length() ) {
- SG_LOG( SG_INSTR, SG_WARN, "Section = " << name );
- }
- }
- }
-}
-
-Altimeter::Altimeter ()
- : _altitude_table(new SGInterpTable)
-{
-
- for (int i = 0; altitude_data[i][0] != -1; i++)
- _altitude_table->addEntry(altitude_data[i][0], altitude_data[i][1]);
-}
+Altimeter::Altimeter ( SGPropertyNode *node, double quantum )
+ : _name(node->getStringValue("name", "altimeter")),
+ _num(node->getIntValue("number", 0)),
+ _static_pressure(node->getStringValue("static-pressure", "/systems/static/pressure-inhg")),
+ _tau(node->getDoubleValue("tau", 0.1)),
+ _quantum(node->getDoubleValue("quantum", quantum))
+{}
Altimeter::~Altimeter ()
-{
- delete _altitude_table;
-}
+{}
void
Altimeter::init ()
{
string branch;
- branch = "/instrumentation/" + name;
- static_port += "/pressure-inhg";
-
- SGPropertyNode *node = fgGetNode(branch.c_str(), num, true );
-
- _serviceable_node = node->getChild("serviceable", 0, true);
- _setting_node = node->getChild("setting-inhg", 0, true);
- _pressure_node = fgGetNode(static_port.c_str(), true);
- _altitude_node = node->getChild("indicated-altitude-ft", 0, true);
-
- _serviceable_node->setBoolValue(true);
- _setting_node->setDoubleValue(29.92);
+ branch = "/instrumentation/" + _name;
+
+ SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
+ raw_PA = 0.0;
+ _kollsman = 0.0;
+ _pressure_node = fgGetNode(_static_pressure.c_str(), true);
+ _serviceable_node = node->getChild("serviceable", 0, true);
+ _setting_node = node->getChild("setting-inhg", 0, true);
+ _press_alt_node = node->getChild("pressure-alt-ft", 0, true);
+ _mode_c_node = node->getChild("mode-c-alt-ft", 0, true);
+ _altitude_node = node->getChild("indicated-altitude-ft", 0, true);
+
+ if (_setting_node->getDoubleValue() == 0)
+ _setting_node->setDoubleValue(29.921260);
}
void
Altimeter::update (double dt)
{
if (_serviceable_node->getBoolValue()) {
+ double trat = _tau > 0 ? dt/_tau : 100;
double pressure = _pressure_node->getDoubleValue();
double setting = _setting_node->getDoubleValue();
-
- // Move towards the current setting
- double last_altitude = _altitude_node->getDoubleValue();
- double current_altitude =
- _altitude_table->interpolate(setting - pressure);
- _altitude_node->setDoubleValue(fgGetLowPass(last_altitude,
- current_altitude,
- dt * RESPONSIVENESS));
+ double press_alt = _press_alt_node->getDoubleValue();
+ // The mechanism settles slowly toward new pressure altitude:
+ raw_PA = fgGetLowPass(raw_PA, _altimeter.press_alt_ft(pressure), trat);
+ _mode_c_node->setDoubleValue(100 * SGMiscd::round(raw_PA/100));
+ _kollsman = fgGetLowPass(_kollsman, _altimeter.kollsman_ft(setting), trat);
+ if (_quantum)
+ press_alt = _quantum * SGMiscd::round(raw_PA/_quantum);
+ else
+ press_alt = raw_PA;
+ _press_alt_node->setDoubleValue(press_alt);
+ _altitude_node->setDoubleValue(press_alt - _kollsman);
}
}
projects / flightgear.git / blobdiff