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 #include <simgear/math/interpolater.hxx>
   7
   8 #include "vertical_speed_indicator.hxx"
   9 #include <Main/fg_props.hxx>
  10 #include <Main/util.hxx>
  11
  12 using std::string;
  13
  14 VerticalSpeedIndicator::VerticalSpeedIndicator ( SGPropertyNode *node )
  15     : _internal_pressure_inhg(29.92),
  16       _name(node->getStringValue("name", "vertical-speed-indicator")),
  17       _num(node->getIntValue("number", 0)),
  18       _static_pressure(node->getStringValue("static-pressure", "/systems/static/pressure-inhg"))
  19 {
  20 }
  21
  22 VerticalSpeedIndicator::~VerticalSpeedIndicator ()
  23 {
  24 }
  25
  26 void
  27 VerticalSpeedIndicator::init ()
  28 {
  29     string branch;
  30     branch = "/instrumentation/" + _name;
  31
  32     SGPropertyNode *node = fgGetNode(branch.c_str(), _num, true );
  33     _serviceable_node = node->getChild("serviceable", 0, true);
  34     _pressure_node = fgGetNode(_static_pressure.c_str(), true);
  35     _speed_node = node->getChild("indicated-speed-fpm", 0, true);
  36     _speed_up_node = fgGetNode("/sim/speed-up", true);
  37
  38                                 // Initialize at ambient pressure
  39     _internal_pressure_inhg = _pressure_node->getDoubleValue();
  40 }
  41
  42 void
  43 VerticalSpeedIndicator::update (double dt)
  44 {
  45                                 // model taken from steam.cxx, with change
  46                                 // from 10000 to 10500 for manual factor
  47     if (_serviceable_node->getBoolValue()) {
  48         double pressure = _pressure_node->getDoubleValue();
  49         double speed_up = _speed_up_node->getDoubleValue();
  50         if( speed_up > 1 )
  51             dt *= speed_up;
  52         _speed_node
  53             ->setDoubleValue((_internal_pressure_inhg - pressure) * 10500);
  54         _internal_pressure_inhg =
  55             fgGetLowPass(_internal_pressure_inhg,
  56                          _pressure_node->getDoubleValue(),
  57                          dt/6.0);
  58     }
  59 }
  60
  61 // end of vertical_speed_indicator.cxx