1 // gps.cxx - distance-measuring equipment.
2 // Written by David Megginson, started 2003.
4 // This file is in the Public Domain and comes with no warranty.
6 #include <simgear/compiler.h>
12 #include <Aircraft/aircraft.hxx>
13 #include <FDM/flight.hxx>
14 #include <Controls/controls.hxx>
15 #include <Scenery/scenery.hxx>
17 #include <simgear/constants.h>
18 #include <simgear/sg_inlines.h>
19 #include <simgear/debug/logstream.hxx>
20 #include <simgear/math/sg_geodesy.hxx>
21 #include <simgear/misc/sg_path.hxx>
22 #include <simgear/route/route.hxx>
24 #include <Airports/simple.hxx>
26 #include <Main/fg_init.hxx>
27 #include <Main/globals.hxx>
28 #include <Main/fg_props.hxx>
29 #include <Main/util.hxx>
30 #include <Navaids/fixlist.hxx>
31 #include <Navaids/navlist.hxx>
40 _last_longitude_deg(0),
41 _last_latitude_deg(0),
54 _longitude_node = fgGetNode("/position/longitude-deg", true);
55 _latitude_node = fgGetNode("/position/latitude-deg", true);
56 _altitude_node = fgGetNode("/position/altitude-ft", true);
57 _magvar_node = fgGetNode("/environment/magnetic-variation-deg", true);
58 _serviceable_node = fgGetNode("/instrumentation/gps/serviceable", true);
59 _electrical_node = fgGetNode("/systems/electrical/outputs/gps", true);
61 fgGetNode("/instrumentation/gps/wp-longitude-deg", true);
63 fgGetNode("/instrumentation/gps/wp-latitude-deg", true);
65 fgGetNode("/instrumentation/gps/wp-ID", true);
67 fgGetNode("/instrumentation/gps/wp-name", true);
69 fgGetNode("/instrumentation/gps/course-deg", true);
70 _get_nearest_airport_node =
71 fgGetNode("/instrumentation/gps/get-nearest-airport", true);
73 fgGetNode("/instrumentation/gps/waypoint-type", true);
75 _raim_node = fgGetNode("/instrumentation/gps/raim", true);
76 _indicated_longitude_node =
77 fgGetNode("/instrumentation/gps/longitude-deg", true);
78 _indicated_latitude_node =
79 fgGetNode("/instrumentation/gps/latitude-deg", true);
80 _indicated_altitude_node =
81 fgGetNode("/instrumentation/gps/altitude-ft", true);
83 fgGetNode("/instrumentation/gps/track-true-deg", true);
84 _magnetic_track_node =
85 fgGetNode("/instrumentation/gps/track-magnetic-deg", true);
87 fgGetNode("/instrumentation/gps/ground-speed-kt", true);
89 fgGetNode("/instrumentation/gps/wp-distance-nm", true);
91 fgGetNode("/instrumentation/gps/TTW",true);
93 fgGetNode("/instrumentation/gps/wp-bearing-deg", true);
94 _wp_actual_radial_node =
95 fgGetNode("/instrumentation/gps/radials/actual-deg", true);
96 _wp_course_deviation_node =
97 fgGetNode("/instrumentation/gps/course-deviation-deg", true);
98 _wp_course_error_nm_node =
99 fgGetNode("/instrumentation/gps/course-error-nm", true);
101 fgGetNode("/instrumentation/gps/to-flag", true);
103 fgGetNode("/instrumentation/gps/odometer", true);
104 _trip_odometer_node =
105 fgGetNode("/instrumentation/gps/trip-odometer", true);
109 GPS::update (double delta_time_sec)
111 // If it's off, don't bother.
112 if (!_serviceable_node->getBoolValue() ||
113 !_electrical_node->getBoolValue()) {
115 _last_longitude_deg = 0;
116 _last_latitude_deg = 0;
117 _last_altitude_m = 0;
119 _raim_node->setDoubleValue(false);
120 _indicated_longitude_node->setDoubleValue(0);
121 _indicated_latitude_node->setDoubleValue(0);
122 _indicated_altitude_node->setDoubleValue(0);
123 _true_track_node->setDoubleValue(0);
124 _magnetic_track_node->setDoubleValue(0);
125 _speed_node->setDoubleValue(0);
126 _wp_distance_node->setDoubleValue(0);
127 _wp_bearing_node->setDoubleValue(0);
128 _wp_actual_radial_node->setDoubleValue(0);
129 _wp_longitude_node->setDoubleValue(0);
130 _wp_latitude_node->setDoubleValue(0);
131 _wp_course_node->setDoubleValue(0);
132 _odometer_node->setDoubleValue(0);
133 _trip_odometer_node->setDoubleValue(0);
137 // Get the aircraft position
138 double longitude_deg = _longitude_node->getDoubleValue();
139 double latitude_deg = _latitude_node->getDoubleValue();
140 double altitude_m = _altitude_node->getDoubleValue() * SG_FEET_TO_METER;
141 double magvar_deg = _magvar_node->getDoubleValue();
145 _raim_node->setBoolValue(true);
146 _indicated_longitude_node->setDoubleValue(longitude_deg);
147 _indicated_latitude_node->setDoubleValue(latitude_deg);
148 _indicated_altitude_node->setDoubleValue(altitude_m * SG_METER_TO_FEET);
151 double track1_deg, track2_deg, distance_m, odometer;
152 geo_inverse_wgs_84(altitude_m,
153 _last_latitude_deg, _last_longitude_deg,
154 latitude_deg, longitude_deg,
155 &track1_deg, &track2_deg, &distance_m);
156 speed_kt = ((distance_m * SG_METER_TO_NM) *
157 ((1 / delta_time_sec) * 3600.0));
158 _true_track_node->setDoubleValue(track1_deg);
159 _magnetic_track_node->setDoubleValue(track1_deg - magvar_deg);
160 speed_kt = fgGetLowPass(_last_speed_kts, speed_kt, delta_time_sec/20.0);
161 _last_speed_kts = speed_kt;
162 _speed_node->setDoubleValue(speed_kt);
164 odometer = _odometer_node->getDoubleValue();
165 _odometer_node->setDoubleValue(odometer + distance_m * SG_METER_TO_NM);
166 odometer = _trip_odometer_node->getDoubleValue();
167 _trip_odometer_node->setDoubleValue(odometer + distance_m * SG_METER_TO_NM);
169 // Get waypoint position
170 double wp_longitude_deg = _wp_longitude_node->getDoubleValue();
171 double wp_latitude_deg = _wp_latitude_node->getDoubleValue();
172 double wp_course_deg =
173 _wp_course_node->getDoubleValue();
174 double wp_distance, wp_bearing_deg, wp_actual_radial_deg,
175 wp_course_deviation_deg, wp_course_error_m, wp_TTW;
176 string wp_ID = _wp_ID_node->getStringValue();
178 // If the get-nearest-airport-node is true.
179 // Get the nearest airport, and set it as waypoint.
180 if (_get_nearest_airport_node->getBoolValue()) {
182 cout << "Airport found" << endl;
183 a = globals->get_airports()->search(longitude_deg, latitude_deg, false);
184 _wp_ID_node->setStringValue(a.id.c_str());
185 wp_longitude_deg = a.longitude;
186 wp_latitude_deg = a.latitude;
187 _wp_name_node->setStringValue(a.name.c_str());
188 _get_nearest_airport_node->setBoolValue(false);
189 _last_wp_ID = wp_ID = a.id.c_str();
192 // If the waypoint ID has changed, try to find the new ID
193 // in the airport-, fix-, nav-database.
194 if ( !(_last_wp_ID == wp_ID) ) {
195 string waypont_type =
196 _waypoint_type_node->getStringValue();
197 if (waypont_type == "airport") {
199 a = globals->get_airports()->search( wp_ID );
200 if ( a.id == wp_ID ) {
201 cout << "Airport found" << endl;
202 wp_longitude_deg = a.longitude;
203 wp_latitude_deg = a.latitude;
204 _wp_name_node->setStringValue(a.name.c_str());
207 else if (waypont_type == "nav") {
209 if ( (n = current_navlist->findByIdent(wp_ID.c_str(),
211 latitude_deg)) != NULL) {
212 cout << "Nav found" << endl;
213 wp_longitude_deg = n->get_lon();
214 wp_latitude_deg = n->get_lat();
215 _wp_name_node->setStringValue(n->get_name().c_str());
218 else if (waypont_type == "fix") {
220 if ( current_fixlist->query(wp_ID, &f) ) {
221 cout << "Fix found" << endl;
222 wp_longitude_deg = f.get_lon();
223 wp_latitude_deg = f.get_lat();
224 _wp_name_node->setStringValue(wp_ID.c_str());
230 // Find the bearing and distance to the waypoint.
231 SGWayPoint wp(wp_longitude_deg, wp_latitude_deg, altitude_m);
232 wp.CourseAndDistance(longitude_deg, latitude_deg, altitude_m,
233 &wp_bearing_deg, &wp_distance);
234 _wp_longitude_node->setDoubleValue(wp_longitude_deg);
235 _wp_latitude_node->setDoubleValue(wp_latitude_deg);
236 _wp_distance_node->setDoubleValue(wp_distance * SG_METER_TO_NM);
237 _wp_bearing_node->setDoubleValue(wp_bearing_deg);
239 // Estimate time to waypoint.
240 // The estimation does not take track into consideration,
241 // so if you are going away from the waypoint the TTW will
242 // increase. Makes most sense when travelling directly towards
244 if (speed_kt > 0.0 && wp_distance > 0.0) {
245 wp_TTW = (wp_distance * SG_METER_TO_NM) / (speed_kt / 3600);
250 unsigned int wp_TTW_seconds = (int) (wp_TTW + 0.5);
251 if (wp_TTW_seconds < 356400) { // That's 99 hours
252 unsigned int wp_TTW_minutes = 0;
253 unsigned int wp_TTW_hours = 0;
255 while (wp_TTW_seconds >= 3600) {
256 wp_TTW_seconds -= 3600;
259 while (wp_TTW_seconds >= 60) {
260 wp_TTW_seconds -= 60;
263 sprintf(wp_TTW_str, "%02d:%02d:%02d",
264 wp_TTW_hours, wp_TTW_minutes, wp_TTW_seconds);
265 _wp_ttw_node->setStringValue(wp_TTW_str);
268 _wp_ttw_node->setStringValue("--:--:--");
271 // We are on the radial 180 degrees from the bearing to the waypoint.
272 wp_actual_radial_deg = wp_bearing - 180.0;
273 while (wp_actual_radial_deg < 0.0) {
274 wp_actual_radial_deg += 360.0; }
275 while (wp_actual_radial_deg >= 360.0) {
276 wp_actual_radial_deg -= 360.0; }
277 _wp_actual_radial_node->setDoubleValue(wp_actual_radial_deg);
279 // We want to be on the radial 180 degrees from the desired course.
280 wp_course_deg -= 180.0;
281 while (wp_course_deg < 0.0) {
282 wp_course_deg += 360.0; }
283 while (wp_course_deg >= 360.0) {
284 wp_course_deg -= 360.0;
288 // Course deviation is the diffenrence between the bearing
290 wp_course_deviation_deg = wp_bearing_deg -
292 while (wp_course_deviation_deg < -180.0) {
293 wp_course_deviation_deg += 360.0; }
294 while (wp_course_deviation_deg > 180.0) {
295 wp_course_deviation_deg -= 360.0; }
297 // If the course deviation is less than 90 degrees to either side,
298 // our desired course is towards the waypoint.
299 // It does not matter if we are actually moving towards or from the waypoint.
300 if (fabs(wp_course_deviation_deg) < 90.0) {
301 _wp_to_flag_node->setBoolValue(true); }
302 // If it's more than 90 degrees the desired course is from the waypoint.
303 else if (fabs(wp_course_deviation_deg) > 90.0) {
304 _wp_to_flag_node->setBoolValue(false);
305 // When the course is away from the waypoint,
306 // it makes sense to change the sign of the deviation.
307 wp_course_deviation_deg *= -1.0;
308 while (wp_course_deviation_deg < -90.0)
309 wp_course_deviation_deg += 180.0;
310 while (wp_course_deviation_deg > 90.0)
311 wp_course_deviation_deg -= 180.0; }
313 _wp_course_deviation_node->setDoubleValue(wp_course_deviation_deg);
315 // Cross track error.
316 wp_course_error_m = sin(wp_course_deviation_deg * SG_PI / 180.0)
318 _wp_course_error_nm_node->setDoubleValue(wp_course_error_m
322 _true_track_node->setDoubleValue(0.0);
323 _magnetic_track_node->setDoubleValue(0.0);
324 _speed_node->setDoubleValue(0.0);
328 _last_longitude_deg = longitude_deg;
329 _last_latitude_deg = latitude_deg;
330 _last_altitude_m = altitude_m;