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
  36                                 // Initialize at ambient pressure
  37     _internal_pressure_inhg = _pressure_node->getDoubleValue();
  38 }
  39
  40 void
  41 VerticalSpeedIndicator::update (double dt)
  42 {
  43                                 // model taken from steam.cxx, with change
  44                                 // from 10000 to 10500 for manual factor
  45     if (_serviceable_node->getBoolValue()) {
  46         double pressure = _pressure_node->getDoubleValue();
  47         _speed_node
  48             ->setDoubleValue((_internal_pressure_inhg - pressure) * 10500);
  49         _internal_pressure_inhg =
  50             fgGetLowPass(_internal_pressure_inhg,
  51                          _pressure_node->getDoubleValue(),
  52                          dt/6.0);
  53     }
  54 }
  55
  56 // end of vertical_speed_indicator.cxx