src/Computer/ThermalLocator.hpp

   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 #ifndef THERMALLOCATOR_H
  25 #define THERMALLOCATOR_H
  26
  27 #include "Math/fixed.hpp"
  28 #include "Geo/GeoPoint.hpp"
  29 #include "Geo/SpeedVector.hpp"
  30 #include "Geo/Flat/FlatPoint.hpp"
  31
  32 class TaskProjection;
  33 struct ThermalLocatorInfo;
  34
  35 /**
  36  * Class to estimate the location of the center of a thermal
  37  * when circling.
  38  */
  39 class ThermalLocator {
  40 public:
  41   static constexpr unsigned TLOCATOR_NMIN = 5;
  42   static constexpr unsigned TLOCATOR_NMAX = 60;
  43
  44 private:
  45   /** Class used to hold thermal estimate samples */
  46   struct Point
  47   {
  48     /**
  49      * Calculate drifted, weighted values of point
  50      *
  51      * @param t Current time
  52      * @param location_0 Initial location
  53      * @param wind_drift Wind drift offset
  54      * @param decay decay factor for weighting
  55      */
  56     void Drift(fixed t, const TaskProjection& projection,
  57                const GeoPoint& wind_drift);
  58
  59     /** Actual location of sample */
  60     GeoPoint location;
  61     /** Projected/drifted sample */
  62     FlatPoint loc_drift;
  63     /** Time of sample (s) */
  64     fixed t_0;
  65     /** Scaled updraft value of sample */
  66     fixed w;
  67     /** Lift weighting used for this point */
  68     fixed lift_weight;
  69     /** Recency weighting used for this point */
  70     fixed recency_weight;
  71   };
  72
  73   /** Circular buffer of points */
  74   Point points[TLOCATOR_NMAX];
  75
  76   /** Index of next point to add */
  77   unsigned n_index;
  78   /** Number of points in buffer */
  79   unsigned n_points;
  80
  81 public:
  82   /**
  83    * Update locator estimate.  If not in circling mode, resets the
  84    * object.
  85    *
  86    * @param circling Whether aircraft is in circling mode
  87    * @param time Time of fix (s)
  88    * @param location Location of aircraft
  89    * @param w Net updraft speed (m/s)
  90    * @param wind Wind vector
  91    * @param therm Output thermal estimate data
  92    */
  93   void Process(const bool circling, const fixed time, const GeoPoint &location,
  94                const fixed w, const SpeedVector wind,
  95                ThermalLocatorInfo& therm);
  96
  97   /**
  98    * Reset as if never flown
  99    */
 100   void Reset();
 101
 102 private:
 103   FlatPoint glider_average();
 104
 105   void AddPoint(const fixed t, const GeoPoint &location, const fixed w);
 106   void Update(const fixed t_0, const GeoPoint &location_0,
 107               const SpeedVector wind, ThermalLocatorInfo &therm);
 108
 109   void Drift(const fixed t_0, const TaskProjection& projection,
 110              const GeoPoint& traildrift);
 111 };
 112
 113 #endif