1 // gsdi.cxx - Ground Speed Drift Angle Indicator (known as GSDI or GSDA)
2 // Written by Melchior FRANZ, started 2006.
4 // Copyright (C) 2006 Melchior FRANZ - mfranz#aon:at
6 // This program is free software; you can redistribute it and/or
7 // modify it under the terms of the GNU General Public License as
8 // published by the Free Software Foundation; either version 2 of the
9 // License, or (at your option) any later version.
11 // This program is distributed in the hope that it will be useful, but
12 // WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 // General Public License for more details.
16 // You should have received a copy of the GNU General Public License
17 // along with this program; if not, write to the Free Software
18 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
24 #include <simgear/sg_inlines.h>
25 #include <simgear/constants.h>
27 #include <Main/fg_props.hxx>
32 * Failures or inaccuracies are currently not modeled due to lack of data.
33 * The Doppler based GSDI should output unreliable data with increasing
34 * pitch, roll, vertical acceleration and altitude-agl.
38 GSDI::GSDI(SGPropertyNode *node) :
42 for (int i = 0; i < node->nChildren(); ++i) {
43 SGPropertyNode *child = node->getChild(i);
44 string name = child->getName();
47 _name = child->getStringValue();
48 } else if (name == "number") {
49 _num = child->getIntValue();
51 SG_LOG(SG_INSTR, SG_WARN, "Error in gsdi config logic");
53 SG_LOG(SG_INSTR, SG_WARN, "Section = " << _name);
72 branch = "/instrumentation/" + _name;
73 SGPropertyNode *n = fgGetNode(branch.c_str(), _num, true);
74 _serviceableN = n->getNode("serviceable", true);
77 _headingN = fgGetNode("/orientation/heading-deg", true);
78 _ubodyN = fgGetNode("/velocities/uBody-fps", true);
79 _vbodyN = fgGetNode("/velocities/vBody-fps", true);
80 _wind_dirN = fgGetNode("/environment/wind-from-heading-deg", true);
81 _wind_speedN = fgGetNode("/environment/wind-speed-kt", true);
84 _drift_uN = n->getNode("drift-u-kt", true);
85 _drift_vN = n->getNode("drift-v-kt", true);
86 _drift_speedN = n->getNode("drift-speed-kt", true);
87 _drift_angleN = n->getNode("drift-angle-deg", true);
91 void GSDI::update(double /*delta_time_sec*/)
93 if (!_serviceableN->getBoolValue())
96 double wind_speed = _wind_speedN->getDoubleValue();
97 double rel_wind_dir = (_headingN->getDoubleValue() - _wind_dirN->getDoubleValue())
98 * SGD_DEGREES_TO_RADIANS;
99 double wind_u = wind_speed * cos(rel_wind_dir);
100 double wind_v = wind_speed * sin(rel_wind_dir);
102 double u = _ubodyN->getDoubleValue() * SG_FPS_TO_KT - wind_u;
103 double v = _vbodyN->getDoubleValue() * SG_FPS_TO_KT + wind_v;
105 double speed = sqrt(u * u + v * v);
106 double angle = atan2(v, u) * SGD_RADIANS_TO_DEGREES;
108 _drift_uN->setDoubleValue(u);
109 _drift_vN->setDoubleValue(v);
110 _drift_speedN->setDoubleValue(speed);
111 _drift_angleN->setDoubleValue(angle);