src/Environment/ridge_lift.cxx

   1 // simulates ridge lift
   2 //
   3 // Written by Patrice Poly
   4 // Copyright (C) 2009 Patrice Poly - p.polypa@gmail.com
   5 //
   6 //
   7 // Entirely based  on the paper :
   8 // http://carrier.csi.cam.ac.uk/forsterlewis/soaring/sim/fsx/dev/sim_probe/sim_probe_paper.html
   9 // by Ian Forster-Lewis, University of Cambridge, 26th December 2007
  10 //
  11 //
  12 // This program is free software; you can redistribute it and/or
  13 // modify it under the terms of the GNU General Public License as
  14 // published by the Free Software Foundation; either version 2 of the
  15 // License, or (at your option) any later version.
  16 //
  17 // This program is distributed in the hope that it will be useful, but
  18 // WITHOUT ANY WARRANTY; without even the implied warranty of
  19 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 // General Public License for more details.
  21 //
  22 // You should have received a copy of the GNU General Public License
  23 // along with this program; if not, write to the Free Software
  24 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  25 //
  26 //
  27
  28
  29 #ifdef HAVE_CONFIG_H
  30 #  include <config.h>
  31 #endif
  32
  33 #include <Main/fg_props.hxx>
  34 #include <Main/globals.hxx>
  35 #include <Scenery/scenery.hxx>
  36 #include <string>
  37 #include <math.h>
  38
  39 using std::string;
  40
  41 #include "ridge_lift.hxx"
  42
  43 //constructor
  44 FGRidgeLift::FGRidgeLift ()
  45 {
  46         dist_probe_m[0] = 0.0; // in meters
  47         dist_probe_m[1] = 250.0;
  48         dist_probe_m[2] = 750.0;
  49         dist_probe_m[3] = 2000.0;
  50         dist_probe_m[4] = -100.0;
  51
  52         BOUNDARY1_m = 40.0; // in meters
  53         BOUNDARY2_m = 130.0;
  54
  55         PI = 4.0*atan(1.0); // pi
  56         deg2rad = (PI/180.0);
  57         rad2deg = (180.0/PI);
  58         strength = 0.0;
  59         timer = 0.0;
  60         scanned = false;
  61
  62         earth_rad_ft=20899773.07;
  63 }
  64
  65 //destructor
  66 FGRidgeLift::~FGRidgeLift()
  67 {
  68
  69 }
  70
  71 void FGRidgeLift::init(void)
  72 {
  73         _ridge_lift_fps_node =
  74                         fgGetNode("/environment/ridge-lift-fps"
  75                         , true);
  76         _surface_wind_from_deg_node =
  77                         fgGetNode("/environment/config/boundary/entry[0]/wind-from-heading-deg"
  78                         , true);
  79         _surface_wind_speed_node =
  80                         fgGetNode("/environment/config/boundary/entry[0]/wind-speed-kt"
  81                         , true);
  82         _earth_radius_node =
  83                         fgGetNode("/position/sea-level-radius-ft"
  84                         , true);
  85         _user_longitude_node =
  86                         fgGetNode("/position/longitude-deg"
  87                         , true);
  88         _user_latitude_node =
  89                         fgGetNode("/position/latitude-deg"
  90                         , true);
  91         _user_altitude_ft_node =
  92                         fgGetNode("/position/altitude-ft"
  93                         , true);
  94         _user_altitude_agl_ft_node =
  95                         fgGetNode("/position/altitude-agl-ft"
  96                         , true);
  97 }
  98
  99 void FGRidgeLift::bind() {
 100
 101         fgTie("/environment/ridge-lift/probe-elev-m[0]", this,
 102                 &FGRidgeLift::get_probe_elev_m_0); // read-only
 103         fgTie("/environment/ridge-lift/probe-elev-m[1]", this,
 104                 &FGRidgeLift::get_probe_elev_m_1); // read-only
 105         fgTie("/environment/ridge-lift/probe-elev-m[2]", this,
 106                 &FGRidgeLift::get_probe_elev_m_2); // read-only
 107         fgTie("/environment/ridge-lift/probe-elev-m[3]", this,
 108                 &FGRidgeLift::get_probe_elev_m_3); // read-only
 109         fgTie("/environment/ridge-lift/probe-elev-m[4]", this,
 110                 &FGRidgeLift::get_probe_elev_m_4); // read-only
 111
 112         fgTie("/environment/ridge-lift/probe-lat-deg[0]", this,
 113                 &FGRidgeLift::get_probe_lat_0); // read-only
 114         fgTie("/environment/ridge-lift/probe-lat-deg[1]", this,
 115                 &FGRidgeLift::get_probe_lat_1); // read-only
 116         fgTie("/environment/ridge-lift/probe-lat-deg[2]", this,
 117                 &FGRidgeLift::get_probe_lat_2); // read-only
 118         fgTie("/environment/ridge-lift/probe-lat-deg[3]", this,
 119                 &FGRidgeLift::get_probe_lat_3); // read-only
 120         fgTie("/environment/ridge-lift/probe-lat-deg[4]", this,
 121                 &FGRidgeLift::get_probe_lat_4); // read-only
 122
 123         fgTie("/environment/ridge-lift/probe-lon-deg[0]", this,
 124                 &FGRidgeLift::get_probe_lon_0); // read-only
 125         fgTie("/environment/ridge-lift/probe-lon-deg[1]", this,
 126                 &FGRidgeLift::get_probe_lon_1); // read-only
 127         fgTie("/environment/ridge-lift/probe-lon-deg[2]", this,
 128                 &FGRidgeLift::get_probe_lon_2); // read-only
 129         fgTie("/environment/ridge-lift/probe-lon-deg[3]", this,
 130                 &FGRidgeLift::get_probe_lon_3); // read-only
 131         fgTie("/environment/ridge-lift/probe-lon-deg[4]", this,
 132                 &FGRidgeLift::get_probe_lon_4); // read-only
 133
 134         fgTie("/environment/ridge-lift/slope[0]", this,
 135                 &FGRidgeLift::get_slope_0); // read-only
 136         fgTie("/environment/ridge-lift/slope[1]", this,
 137                 &FGRidgeLift::get_slope_1); // read-only
 138         fgTie("/environment/ridge-lift/slope[2]", this,
 139                 &FGRidgeLift::get_slope_2); // read-only
 140         fgTie("/environment/ridge-lift/slope[3]", this,
 141                 &FGRidgeLift::get_slope_3); // read-only
 142
 143 }
 144
 145 void FGRidgeLift::unbind() {
 146
 147         fgUntie("/environment/ridge-lift/probe-elev-m[0]");
 148         fgUntie("/environment/ridge-lift/probe-elev-m[1]");
 149         fgUntie("/environment/ridge-lift/probe-elev-m[2]");
 150         fgUntie("/environment/ridge-lift/probe-elev-m[3]");
 151         fgUntie("/environment/ridge-lift/probe-elev-m[4]");
 152
 153         fgUntie("/environment/ridge-lift/probe-lat-deg[0]");
 154         fgUntie("/environment/ridge-lift/probe-lat-deg[1]");
 155         fgUntie("/environment/ridge-lift/probe-lat-deg[2]");
 156         fgUntie("/environment/ridge-lift/probe-lat-deg[3]");
 157         fgUntie("/environment/ridge-lift/probe-lat-deg[4]");
 158
 159         fgUntie("/environment/ridge-lift/probe-lon-deg[0]");
 160         fgUntie("/environment/ridge-lift/probe-lon-deg[1]");
 161         fgUntie("/environment/ridge-lift/probe-lon-deg[2]");
 162         fgUntie("/environment/ridge-lift/probe-lon-deg[3]");
 163         fgUntie("/environment/ridge-lift/probe-lon-deg[4]");
 164
 165         fgUntie("/environment/ridge-lift/slope[0]");
 166         fgUntie("/environment/ridge-lift/slope[1]");
 167         fgUntie("/environment/ridge-lift/slope[2]");
 168         fgUntie("/environment/ridge-lift/slope[3]");
 169
 170 }
 171
 172 void FGRidgeLift::update(double dt) {
 173         Run(dt);
 174 }
 175
 176 double FGRidgeLift::sign(double x) {
 177     if (x == 0.0)
 178         return x;
 179     else
 180         return x/fabs(x);
 181 }
 182
 183 void FGRidgeLift::Run(double dt) {
 184
 185         // copy values
 186
 187         user_latitude_deg  = _user_latitude_node->getDoubleValue();
 188         user_longitude_deg = _user_longitude_node->getDoubleValue();
 189         //user_altitude_ft  = _user_altitude_ft_node->getDoubleValue();
 190
 191         if ( ( _earth_radius_node->getDoubleValue() ) > 1.0 ) {
 192         earth_rad_ft =_earth_radius_node->getDoubleValue(); }
 193         else {  earth_rad_ft=20899773.07; }
 194
 195         //earth_rad_m = earth_rad_ft * 0.3048 ;
 196         earth_rad_m = earth_rad_ft * SG_FEET_TO_METER ;
 197
 198         //get the windspeed at ground level
 199
 200         double ground_wind_from_deg = _surface_wind_from_deg_node->getDoubleValue();
 201         double ground_wind_speed_kts  = _surface_wind_speed_node->getDoubleValue();
 202         //double ground_wind_speed_mps = ground_wind_speed_kts / SG_METER_TO_FEET;
 203         double ground_wind_speed_mps = ground_wind_speed_kts / 3.2808399;
 204
 205         double ground_wind_from_rad = (user_longitude_deg < 0.0)  ?
 206                 PI*( ground_wind_from_deg/180.0) +PI : PI*( ground_wind_from_deg/180.0);
 207
 208         // Placing the probes
 209
 210         for (int i = 0; i <= 4; i++)
 211         {
 212                         probe_lat_rad[i] = asin(sin(deg2rad*user_latitude_deg)*cos(dist_probe_m[i]/earth_rad_m)
 213                                 +cos(deg2rad*user_latitude_deg)*sin(dist_probe_m[i]/earth_rad_m)*cos(ground_wind_from_rad));
 214                 if (probe_lat_rad[i] == 0.0) {
 215                         probe_lon_rad[i] = (deg2rad*user_latitude_deg);      // probe on a pole
 216                 }
 217                 else {
 218                         probe_lon_rad[i] = fmod((deg2rad*user_longitude_deg+asin(sin(ground_wind_from_rad)
 219                                                 *sin(dist_probe_m[i]/earth_rad_m)/cos(probe_lon_rad[i]))+PI)
 220                                         ,(2.0*PI))-PI;
 221                 }
 222                 probe_lat_deg[i]= rad2deg*probe_lat_rad[i];
 223                 probe_lon_deg[i]= rad2deg*probe_lon_rad[i];
 224         }
 225
 226         // ground elevations
 227         // every second
 228
 229         timer += dt;
 230         if (timer >= 1.0 ) {
 231                 scanned = true;
 232                 for (int i = 0; i <= 4; i++)
 233                 {
 234                         if (globals->get_scenery()->get_elevation_m(SGGeod::fromGeodM(
 235                             SGGeod::fromRad(probe_lon_rad[i],probe_lat_rad[i]), 20000), alt, 0))
 236                         {
 237                                 probe_elev_m[i] =  alt;
 238                         }
 239                 }
 240                 timer = 0.0;
 241
 242         }
 243
 244         // slopes
 245
 246         double adj_slope[5];
 247
 248         slope[0] = (probe_elev_m[0] - probe_elev_m[1]) / dist_probe_m[1];
 249         slope[1] = (probe_elev_m[1] - probe_elev_m[2]) / dist_probe_m[2];
 250         slope[2] = (probe_elev_m[2] - probe_elev_m[3]) / dist_probe_m[3];
 251         slope[3] = (probe_elev_m[4] - probe_elev_m[0]) / -dist_probe_m[4];
 252
 253         for (int i = 0; i <= 4; i++)
 254         {
 255                 adj_slope[i] = sin(atan(5.0 * pow ( (abs(slope[i])),1.7) ) ) *sign(slope[i]);
 256         }
 257
 258         //adjustment
 259
 260         adj_slope[0] = 0.2 * adj_slope[0];
 261         adj_slope[1] = 0.2 * adj_slope[1];
 262         if ( adj_slope [2] < 0.0 )
 263         {
 264                 adj_slope[2] = 0.5 * adj_slope[2];
 265         }
 266         else
 267         {
 268                 adj_slope[2] = 0.0 ;
 269         }
 270
 271         if ( ( adj_slope [0] >= 0.0 ) && ( adj_slope [3] < 0.0 ) )
 272         {
 273                 adj_slope[3] = 0.0;
 274         }
 275         else
 276         {
 277                 adj_slope[3] = 0.2 * adj_slope[3];
 278         }
 279
 280         double lift_factor = adj_slope[0]+adj_slope[1]+adj_slope[2]+adj_slope[3];
 281
 282         //user altitude above ground
 283
 284         user_altitude_agl_ft = _user_altitude_agl_ft_node->getDoubleValue();
 285         user_altitude_agl_m = ( user_altitude_agl_ft / SG_METER_TO_FEET );
 286
 287         //boundaries
 288         double agl_factor;
 289
 290         if ( user_altitude_agl_m < BOUNDARY1_m )
 291         {
 292                 agl_factor = 0.5+0.5*user_altitude_agl_m /BOUNDARY1_m ;
 293         }
 294         else if ( user_altitude_agl_m < BOUNDARY2_m )
 295         {
 296                 agl_factor = 1.0;
 297         }
 298         else
 299         {
 300                 agl_factor =  exp(-(2 + 2 * probe_elev_m[0] / 4000) *
 301                                 (user_altitude_agl_m - BOUNDARY2_m) / max(probe_elev_m[0],200.0));
 302         }
 303
 304         double lift_mps = lift_factor* ground_wind_speed_mps * agl_factor;
 305
 306         //the updraft, finally, in ft per second
 307         strength = lift_mps * SG_METER_TO_FEET ;
 308
 309         _ridge_lift_fps_node->setDoubleValue( strength );
 310
 311 }
 312
 313
 314
 315
 316
 317