src/Instrumentation/vertical_speed_indicator.cxx

   1 // vertical_speed_indicator.cxx - a regular VSI.
   2 // Written by David Megginson, started 2002.
   3 //
   4 // This file is in the Public Domain and comes with no warranty.
   5
   6 #ifdef HAVE_CONFIG_H
   7 #  include "config.h"
   8 #endif
   9
  10 #include <simgear/math/interpolater.hxx>
  11
  12 #include "vertical_speed_indicator.hxx"
  13 #include <Main/fg_props.hxx>
  14 #include <Main/util.hxx>
  15
  16 using std::string;
  17
  18 VerticalSpeedIndicator::VerticalSpeedIndicator ( SGPropertyNode *node )
  19     : _internal_pressure_inhg(29.92),
  20       _name(node->getStringValue("name", "vertical-speed-indicator")),
  21       _num(node->getIntValue("number", 0)),
  22       _static_pressure(node->getStringValue("static-pressure", "/systems/static/pressure-inhg"))
  23 {
  24 }
  25
  26 VerticalSpeedIndicator::~VerticalSpeedIndicator ()
  27 {
  28 }
  29
  30 void
  31 VerticalSpeedIndicator::init ()
  32 {
  33     string branch;
  34     branch = "/instrumentation/" + _name;
  35
  36     SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
  37     _serviceable_node = node->getChild("serviceable", 0, true);
  38     _pressure_node = fgGetNode(_static_pressure.c_str(), true);
  39     _speed_node = node->getChild("indicated-speed-fpm", 0, true);
  40     _speed_up_node = fgGetNode("/sim/speed-up", true);
  41
  42                                 // Initialize at ambient pressure
  43     _internal_pressure_inhg = _pressure_node->getDoubleValue();
  44 }
  45
  46 void
  47 VerticalSpeedIndicator::update (double dt)
  48 {
  49                                 // model taken from steam.cxx, with change
  50                                 // from 10000 to 10500 for manual factor
  51     if (_serviceable_node->getBoolValue()) {
  52         double pressure = _pressure_node->getDoubleValue();
  53         double speed_up = _speed_up_node->getDoubleValue();
  54         if( speed_up > 1 )
  55             dt *= speed_up;
  56         _speed_node
  57             ->setDoubleValue((_internal_pressure_inhg - pressure) * 10500);
  58         _internal_pressure_inhg =
  59             fgGetLowPass(_internal_pressure_inhg,
  60                          _pressure_node->getDoubleValue(),
  61                          dt/6.0);
  62     }
  63 }
  64
  65 // end of vertical_speed_indicator.cxx