1 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
3 Module: FGPropagate.cpp
6 Purpose: Integrate the EOM to determine instantaneous position
9 ------------- Copyright (C) 1999 Jon S. Berndt (jsb@hal-pc.org) -------------
11 This program is free software; you can redistribute it and/or modify it under
12 the terms of the GNU General Public License as published by the Free Software
13 Foundation; either version 2 of the License, or (at your option) any later
16 This program is distributed in the hope that it will be useful, but WITHOUT
17 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
18 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
21 You should have received a copy of the GNU General Public License along with
22 this program; if not, write to the Free Software Foundation, Inc., 59 Temple
23 Place - Suite 330, Boston, MA 02111-1307, USA.
25 Further information about the GNU General Public License can also be found on
26 the world wide web at http://www.gnu.org.
28 FUNCTIONAL DESCRIPTION
29 --------------------------------------------------------------------------------
30 This class encapsulates the integration of rates and accelerations to get the
31 current position of the aircraft.
34 --------------------------------------------------------------------------------
37 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
38 COMMENTS, REFERENCES, and NOTES
39 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
40 [1] Cooke, Zyda, Pratt, and McGhee, "NPSNET: Flight Simulation Dynamic Modeling
41 Using Quaternions", Presence, Vol. 1, No. 4, pp. 404-420 Naval Postgraduate
43 [2] D. M. Henderson, "Euler Angles, Quaternions, and Transformation Matrices",
45 [3] Richard E. McFarland, "A Standard Kinematic Model for Flight Simulation at
46 NASA-Ames", NASA CR-2497, January 1975
47 [4] Barnes W. McCormick, "Aerodynamics, Aeronautics, and Flight Mechanics",
48 Wiley & Sons, 1979 ISBN 0-471-03032-5
49 [5] Bernard Etkin, "Dynamics of Flight, Stability and Control", Wiley & Sons,
50 1982 ISBN 0-471-08936-2
52 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
57 # include <simgear/compiler.h>
58 # ifdef SG_HAVE_STD_INCLUDES
66 # if defined(sgi) && !defined(__GNUC__)
68 # if (_COMPILER_VERSION < 740)
79 #include "FGPropagate.h"
81 #include <FGFDMExec.h>
82 #include "FGAircraft.h"
83 #include "FGMassBalance.h"
84 #include "FGInertial.h"
85 #include <input_output/FGPropertyManager.h>
89 static const char *IdSrc = "$Id$";
90 static const char *IdHdr = ID_PROPAGATE;
92 /*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
94 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/
96 FGPropagate::FGPropagate(FGFDMExec* fdmex) : FGModel(fdmex)
104 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
106 FGPropagate::~FGPropagate(void)
112 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
114 bool FGPropagate::InitModel(void)
116 FGModel::InitModel();
118 SeaLevelRadius = Inertial->RefRadius(); // For initialization ONLY
119 RunwayRadius = SeaLevelRadius;
121 VState.vLocation.SetRadius( SeaLevelRadius + 4.0 );
126 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
128 void FGPropagate::SetInitialState(const FGInitialCondition *FGIC)
130 SeaLevelRadius = FGIC->GetSeaLevelRadiusFtIC();
131 RunwayRadius = SeaLevelRadius;
133 // Set the position lat/lon/radius
134 VState.vLocation = FGLocation( FGIC->GetLongitudeRadIC(),
135 FGIC->GetLatitudeRadIC(),
136 FGIC->GetAltitudeFtIC() + FGIC->GetSeaLevelRadiusFtIC() );
138 // Set the Orientation from the euler angles
139 VState.vQtrn = FGQuaternion( FGIC->GetPhiRadIC(),
140 FGIC->GetThetaRadIC(),
141 FGIC->GetPsiRadIC() );
143 // Set the velocities in the instantaneus body frame
144 VState.vUVW = FGColumnVector3( FGIC->GetUBodyFpsIC(),
145 FGIC->GetVBodyFpsIC(),
146 FGIC->GetWBodyFpsIC() );
148 // Set the angular velocities in the instantaneus body frame.
149 VState.vPQR = FGColumnVector3( FGIC->GetPRadpsIC(),
151 FGIC->GetRRadpsIC() );
153 // Compute some derived values.
154 vVel = VState.vQtrn.GetTInv()*VState.vUVW;
156 // Finally, make sure that the quaternion stays normalized.
157 VState.vQtrn.Normalize();
159 // Recompute the RunwayRadius level.
160 RecomputeRunwayRadius();
163 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
165 Purpose: Called on a schedule to perform EOM integration
166 Notes: [JB] Run in standalone mode, SeaLevelRadius will be reference radius.
167 In FGFS, SeaLevelRadius is stuffed from FGJSBSim in JSBSim.cxx each pass.
169 At the top of this Run() function, see several "shortcuts" (or, aliases) being
170 set up for use later, rather than using the longer class->function() notation.
172 Here, propagation of state is done using a simple explicit Euler scheme (see the
173 bottom of the function). This propagation is done using the current state values
174 and current derivatives. Based on these values we compute an approximation to the
175 state values for (now + dt).
179 bool FGPropagate::Run(void)
181 if (FGModel::Run()) return true; // Fast return if we have nothing to do ...
182 if (FDMExec->Holding()) return false;
184 RecomputeRunwayRadius();
186 double dt = State->Getdt()*rate; // The 'stepsize'
187 const FGColumnVector3 omega( 0.0, 0.0, Inertial->omega() ); // earth rotation
188 const FGColumnVector3& vForces = Aircraft->GetForces(); // current forces
189 const FGColumnVector3& vMoments = Aircraft->GetMoments(); // current moments
191 double mass = MassBalance->GetMass(); // mass
192 const FGMatrix33& J = MassBalance->GetJ(); // inertia matrix
193 const FGMatrix33& Jinv = MassBalance->GetJinv(); // inertia matrix inverse
194 double r = GetRadius(); // radius
195 if (r == 0.0) {cerr << "radius = 0 !" << endl; r = 1e-16;} // radius check
197 FGColumnVector3 gAccel( 0.0, 0.0, Inertial->GetGAccel(r) );
199 // The rotation matrices:
200 const FGMatrix33& Tl2b = GetTl2b(); // local to body frame
201 const FGMatrix33& Tb2l = GetTb2l(); // body to local frame
202 const FGMatrix33& Tec2l = VState.vLocation.GetTec2l(); // earth centered to local frame
203 const FGMatrix33& Tl2ec = VState.vLocation.GetTl2ec(); // local to earth centered frame
205 // Inertial angular velocity measured in the body frame.
206 const FGColumnVector3 pqri = VState.vPQR + Tl2b*(Tec2l*omega);
208 // Compute vehicle velocity wrt EC frame, expressed in Local horizontal frame.
209 vVel = Tb2l * VState.vUVW;
211 // First compute the time derivatives of the vehicle state values:
213 // Compute body frame rotational accelerations based on the current body moments
214 vPQRdot = Jinv*(vMoments - pqri*(J*pqri));
216 // Compute body frame accelerations based on the current body forces
217 vUVWdot = VState.vUVW*VState.vPQR + vForces/mass;
219 // Coriolis acceleration.
220 FGColumnVector3 ecVel = Tl2ec*vVel;
221 FGColumnVector3 ace = 2.0*omega*ecVel;
222 vUVWdot -= Tl2b*(Tec2l*ace);
224 if (!GroundReactions->GetWOW()) {
225 // Centrifugal acceleration.
226 FGColumnVector3 aeec = omega*(omega*VState.vLocation);
227 vUVWdot -= Tl2b*(Tec2l*aeec);
231 vUVWdot += Tl2b*gAccel;
233 // Compute vehicle velocity wrt EC frame, expressed in EC frame
234 FGColumnVector3 vLocationDot = Tl2ec * vVel;
236 FGColumnVector3 omegaLocal( rInv*vVel(eEast),
238 -rInv*vVel(eEast)*VState.vLocation.GetTanLatitude() );
240 // Compute quaternion orientation derivative on current body rates
241 FGQuaternion vQtrndot = VState.vQtrn.GetQDot( VState.vPQR - Tl2b*omegaLocal );
243 // Propagate velocities
244 VState.vPQR += dt*vPQRdot;
245 VState.vUVW += dt*vUVWdot;
247 // Propagate positions
248 VState.vQtrn += dt*vQtrndot;
249 VState.vLocation += dt*vLocationDot;
254 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
256 void FGPropagate::RecomputeRunwayRadius(void)
258 // Get the runway radius.
259 FGLocation contactloc;
261 FGGroundCallback* gcb = FDMExec->GetGroundCallback();
262 double t = State->Getsim_time();
263 gcb->GetAGLevel(t, VState.vLocation, contactloc, dv, dv);
264 RunwayRadius = contactloc.GetRadius();
267 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
269 void FGPropagate::Seth(double tt)
271 VState.vLocation.SetRadius( tt + SeaLevelRadius );
274 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
276 double FGPropagate::GetRunwayRadius(void) const
281 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
283 double FGPropagate::GetDistanceAGL(void) const
285 return VState.vLocation.GetRadius() - RunwayRadius;
288 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
290 void FGPropagate::SetDistanceAGL(double tt)
292 VState.vLocation.SetRadius( tt + RunwayRadius );
295 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
297 void FGPropagate::bind(void)
299 typedef double (FGPropagate::*PMF)(int) const;
300 PropertyManager->Tie("velocities/h-dot-fps", this, &FGPropagate::Gethdot);
302 PropertyManager->Tie("velocities/v-north-fps", this, eNorth, (PMF)&FGPropagate::GetVel);
303 PropertyManager->Tie("velocities/v-east-fps", this, eEast, (PMF)&FGPropagate::GetVel);
304 PropertyManager->Tie("velocities/v-down-fps", this, eDown, (PMF)&FGPropagate::GetVel);
306 PropertyManager->Tie("velocities/u-fps", this, eU, (PMF)&FGPropagate::GetUVW);
307 PropertyManager->Tie("velocities/v-fps", this, eV, (PMF)&FGPropagate::GetUVW);
308 PropertyManager->Tie("velocities/w-fps", this, eW, (PMF)&FGPropagate::GetUVW);
310 PropertyManager->Tie("velocities/p-rad_sec", this, eP, (PMF)&FGPropagate::GetPQR);
311 PropertyManager->Tie("velocities/q-rad_sec", this, eQ, (PMF)&FGPropagate::GetPQR);
312 PropertyManager->Tie("velocities/r-rad_sec", this, eR, (PMF)&FGPropagate::GetPQR);
314 PropertyManager->Tie("accelerations/pdot-rad_sec", this, eP, (PMF)&FGPropagate::GetPQRdot);
315 PropertyManager->Tie("accelerations/qdot-rad_sec", this, eQ, (PMF)&FGPropagate::GetPQRdot);
316 PropertyManager->Tie("accelerations/rdot-rad_sec", this, eR, (PMF)&FGPropagate::GetPQRdot);
318 PropertyManager->Tie("accelerations/udot-fps", this, eU, (PMF)&FGPropagate::GetUVWdot);
319 PropertyManager->Tie("accelerations/vdot-fps", this, eV, (PMF)&FGPropagate::GetUVWdot);
320 PropertyManager->Tie("accelerations/wdot-fps", this, eW, (PMF)&FGPropagate::GetUVWdot);
322 PropertyManager->Tie("position/h-sl-ft", this, &FGPropagate::Geth, &FGPropagate::Seth, true);
323 PropertyManager->Tie("position/lat-gc-rad", this, &FGPropagate::GetLatitude, &FGPropagate::SetLatitude);
324 PropertyManager->Tie("position/long-gc-rad", this, &FGPropagate::GetLongitude, &FGPropagate::SetLongitude);
325 PropertyManager->Tie("position/h-agl-ft", this, &FGPropagate::GetDistanceAGL, &FGPropagate::SetDistanceAGL);
326 PropertyManager->Tie("position/radius-to-vehicle-ft", this, &FGPropagate::GetRadius);
328 PropertyManager->Tie("metrics/runway-radius", this, &FGPropagate::GetRunwayRadius);
330 PropertyManager->Tie("attitude/phi-rad", this, (int)ePhi, (PMF)&FGPropagate::GetEuler);
331 PropertyManager->Tie("attitude/theta-rad", this, (int)eTht, (PMF)&FGPropagate::GetEuler);
332 PropertyManager->Tie("attitude/psi-rad", this, (int)ePsi, (PMF)&FGPropagate::GetEuler);
334 PropertyManager->Tie("attitude/roll-rad", this, (int)ePhi, (PMF)&FGPropagate::GetEuler);
335 PropertyManager->Tie("attitude/pitch-rad", this, (int)eTht, (PMF)&FGPropagate::GetEuler);
336 PropertyManager->Tie("attitude/heading-true-rad", this, (int)ePsi, (PMF)&FGPropagate::GetEuler);
339 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
341 void FGPropagate::unbind(void)
343 PropertyManager->Untie("velocities/v-north-fps");
344 PropertyManager->Untie("velocities/v-east-fps");
345 PropertyManager->Untie("velocities/v-down-fps");
346 PropertyManager->Untie("velocities/h-dot-fps");
347 PropertyManager->Untie("velocities/u-fps");
348 PropertyManager->Untie("velocities/v-fps");
349 PropertyManager->Untie("velocities/w-fps");
350 PropertyManager->Untie("velocities/p-rad_sec");
351 PropertyManager->Untie("velocities/q-rad_sec");
352 PropertyManager->Untie("velocities/r-rad_sec");
353 PropertyManager->Untie("accelerations/udot-fps");
354 PropertyManager->Untie("accelerations/vdot-fps");
355 PropertyManager->Untie("accelerations/wdot-fps");
356 PropertyManager->Untie("accelerations/pdot-rad_sec");
357 PropertyManager->Untie("accelerations/qdot-rad_sec");
358 PropertyManager->Untie("accelerations/rdot-rad_sec");
359 PropertyManager->Untie("position/h-sl-ft");
360 PropertyManager->Untie("position/lat-gc-rad");
361 PropertyManager->Untie("position/long-gc-rad");
362 PropertyManager->Untie("position/h-agl-ft");
363 PropertyManager->Untie("position/radius-to-vehicle-ft");
364 PropertyManager->Untie("metrics/runway-radius");
365 PropertyManager->Untie("attitude/phi-rad");
366 PropertyManager->Untie("attitude/theta-rad");
367 PropertyManager->Untie("attitude/psi-rad");
368 PropertyManager->Untie("attitude/roll-rad");
369 PropertyManager->Untie("attitude/pitch-rad");
370 PropertyManager->Untie("attitude/heading-true-rad");
373 //%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
374 // The bitmasked value choices are as follows:
375 // unset: In this case (the default) JSBSim would only print
376 // out the normally expected messages, essentially echoing
377 // the config files as they are read. If the environment
378 // variable is not set, debug_lvl is set to 1 internally
379 // 0: This requests JSBSim not to output any messages
381 // 1: This value explicity requests the normal JSBSim
383 // 2: This value asks for a message to be printed out when
384 // a class is instantiated
385 // 4: When this value is set, a message is displayed when a
386 // FGModel object executes its Run() method
387 // 8: When this value is set, various runtime state variables
388 // are printed out periodically
389 // 16: When set various parameters are sanity checked and
390 // a message is printed out when they go out of bounds
392 void FGPropagate::Debug(int from)
394 if (debug_lvl <= 0) return;
396 if (debug_lvl & 1) { // Standard console startup message output
397 if (from == 0) { // Constructor
401 if (debug_lvl & 2 ) { // Instantiation/Destruction notification
402 if (from == 0) cout << "Instantiated: FGPropagate" << endl;
403 if (from == 1) cout << "Destroyed: FGPropagate" << endl;
405 if (debug_lvl & 4 ) { // Run() method entry print for FGModel-derived objects
407 if (debug_lvl & 8 ) { // Runtime state variables
409 if (debug_lvl & 16) { // Sanity checking
411 if (debug_lvl & 64) {
412 if (from == 0) { // Constructor
413 cout << IdSrc << endl;
414 cout << IdHdr << endl;