src/Computer/Wind/Computer.cpp

   1 /*
   2 Copyright_License {
   3
   4   XCSoar Glide Computer - http://www.xcsoar.org/
   5   Copyright (C) 2000-2013 The XCSoar Project
   6   A detailed list of copyright holders can be found in the file "AUTHORS".
   7
   8   This program is free software; you can redistribute it and/or
   9   modify it under the terms of the GNU General Public License
  10   as published by the Free Software Foundation; either version 2
  11   of the License, or (at your option) any later version.
  12
  13   This program is distributed in the hope that it will be useful,
  14   but WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16   GNU General Public License for more details.
  17
  18   You should have received a copy of the GNU General Public License
  19   along with this program; if not, write to the Free Software
  20   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21 }
  22 */
  23
  24 #include "Computer.hpp"
  25 #include "Settings.hpp"
  26 #include "NMEA/MoreData.hpp"
  27 #include "NMEA/Derived.hpp"
  28
  29 void
  30 WindComputer::Reset()
  31 {
  32   last_circling = false;
  33
  34   circling_wind.Reset();
  35   wind_ekf.Reset();
  36   wind_store.reset();
  37 }
  38
  39 gcc_pure
  40 static fixed
  41 GetVTakeoffFallback(const GlidePolar &glide_polar)
  42 {
  43   return glide_polar.IsValid()
  44     ? glide_polar.GetVTakeoff()
  45     /* if there's no valid polar, assume 10 m/s (36 km/h); that's an
  46        arbitrary value, but better than nothing */
  47     : fixed(10);
  48 }
  49
  50 void
  51 WindComputer::Compute(const WindSettings &settings,
  52                       const GlidePolar &glide_polar,
  53                       const MoreData &basic, DerivedInfo &calculated)
  54 {
  55   if (settings.CirclingWindEnabled() &&
  56       calculated.circling != last_circling)
  57     circling_wind.NewFlightMode(calculated);
  58
  59   last_circling = calculated.circling;
  60
  61   if (!calculated.flight.flying)
  62     return;
  63
  64   if (settings.CirclingWindEnabled() &&
  65       calculated.turn_mode == CirclingMode::CLIMB) {
  66     CirclingWind::Result result = circling_wind.NewSample(basic);
  67     if (result.IsValid())
  68       wind_store.SlotMeasurement(basic, result.wind, result.quality);
  69   }
  70
  71   if (settings.ZigZagWindEnabled() &&
  72       basic.airspeed_available && basic.airspeed_real &&
  73       basic.true_airspeed > GetVTakeoffFallback(glide_polar)) {
  74     WindEKFGlue::Result result = wind_ekf.Update(basic, calculated);
  75     if (result.quality > 0) {
  76       Vector v_wind = Vector(result.wind);
  77       wind_store.SlotMeasurement(basic, v_wind, result.quality);
  78     }
  79   }
  80
  81   if (settings.IsAutoWindEnabled())
  82     wind_store.SlotAltitude(basic, calculated);
  83 }
  84
  85 void
  86 WindComputer::ComputeHeadWind(const NMEAInfo &basic, DerivedInfo &info)
  87 {
  88   if (info.wind_available) {
  89     // If any wind information available
  90     // .. calculate headwind from given wind information
  91
  92     info.head_wind =
  93       (info.wind.bearing - basic.attitude.heading).fastcosine()
  94       * info.wind.norm;
  95     info.head_wind_available.Update(basic.clock);
  96   } else {
  97     // No information available that let us calculate the head wind
  98     info.head_wind_available.Clear();
  99   }
 100 }
 101
 102 void
 103 WindComputer::Select(const WindSettings &settings,
 104                      const NMEAInfo &basic, DerivedInfo &calculated)
 105 {
 106   if (basic.external_wind_available && settings.use_external_wind) {
 107     // external wind available
 108     calculated.wind = basic.external_wind;
 109     calculated.wind_available = basic.external_wind_available;
 110     calculated.wind_source = DerivedInfo::WindSource::EXTERNAL;
 111
 112   } else if (settings.manual_wind_available && !settings.IsAutoWindEnabled()) {
 113     // manual wind only if available and desired
 114     calculated.wind = settings.manual_wind;
 115     calculated.wind_available = settings.manual_wind_available;
 116     calculated.wind_source = DerivedInfo::WindSource::MANUAL;
 117
 118   } else if (calculated.estimated_wind_available.Modified(settings.manual_wind_available)
 119              && settings.IsAutoWindEnabled()) {
 120     // auto wind when available and newer than manual wind
 121     calculated.wind = calculated.estimated_wind;
 122     calculated.wind_available = calculated.estimated_wind_available;
 123     calculated.wind_source = DerivedInfo::WindSource::AUTO;
 124
 125   } else if (settings.manual_wind_available
 126              && settings.IsAutoWindEnabled()) {
 127     // manual wind overrides auto wind if available
 128     calculated.wind = settings.manual_wind;
 129     calculated.wind_available = settings.manual_wind_available;
 130     calculated.wind_source = DerivedInfo::WindSource::MANUAL;
 131
 132   } else {
 133     // no wind available
 134     calculated.wind_available.Clear();
 135     calculated.wind_source = DerivedInfo::WindSource::NONE;
 136   }
 137 }