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