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flightgear/src/FDM/JSBSim/FGInitialCondition.cpp

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/*******************************************************************************
Header: FGInitialCondition.cpp
Author: Tony Peden
Date started: 7/1/99
------------- Copyright (C) 1999 Anthony K. Peden (apeden@earthlink.net) -------------
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA.
Further information about the GNU General Public License can also be found on
the world wide web at http://www.gnu.org.
HISTORY
--------------------------------------------------------------------------------
7/1/99 TP Created
FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
The purpose of this class is to take a set of initial conditions and provide
a kinematically consistent set of body axis velocity components, euler
angles, and altitude. This class does not attempt to trim the model i.e.
the sim will most likely start in a very dynamic state (unless, of course,
you have chosen your IC's wisely) even after setting it up with this class.
********************************************************************************
INCLUDES
*******************************************************************************/
#include "FGInitialCondition.h"
#include "FGFDMExec.h"
#include "FGState.h"
#include "FGAtmosphere.h"
#include "FGFCS.h"
#include "FGAircraft.h"
#include "FGTranslation.h"
#include "FGRotation.h"
#include "FGPosition.h"
#include "FGAuxiliary.h"
#include "FGOutput.h"
#include "FGConfigFile.h"
static const char *IdSrc = "$Id$";
static const char *IdHdr = ID_INITIALCONDITION;
//******************************************************************************
FGInitialCondition::FGInitialCondition(FGFDMExec *FDMExec)
{
vt=vc=ve=vg=0;
mach=0;
alpha=beta=gamma=0;
theta=phi=psi=0;
altitude=hdot=0;
latitude=longitude=0;
u=v=w=0;
uw=vw=ww=0;
vnorth=veast=vdown=0;
wnorth=weast=wdown=0;
whead=wcross=0;
wdir=wmag=0;
lastSpeedSet=setvt;
lastWindSet=setwned;
sea_level_radius = FDMExec->GetInertial()->RefRadius();
radius_to_vehicle = FDMExec->GetInertial()->RefRadius();
terrain_altitude = 0;
salpha=sbeta=stheta=sphi=spsi=sgamma=0;
calpha=cbeta=ctheta=cphi=cpsi=cgamma=1;
if(FDMExec != NULL ) {
fdmex=FDMExec;
fdmex->GetPosition()->Seth(altitude);
fdmex->GetAtmosphere()->Run();
} else {
cout << "FGInitialCondition: This class requires a pointer to a valid FGFDMExec object" << endl;
}
if (debug_lvl & 2) cout << "Instantiated: FGInitialCondition" << endl;
}
//******************************************************************************
FGInitialCondition::~FGInitialCondition()
{
if (debug_lvl & 2) cout << "Destroyed: FGInitialCondition" << endl;
}
//******************************************************************************
void FGInitialCondition::SetVcalibratedKtsIC(double tt) {
if(getMachFromVcas(&mach,tt*ktstofps)) {
//cout << "Mach: " << mach << endl;
lastSpeedSet=setvc;
vc=tt*ktstofps;
vt=mach*fdmex->GetAtmosphere()->GetSoundSpeed();
ve=vt*sqrt(fdmex->GetAtmosphere()->GetDensityRatio());
//cout << "Vt: " << vt*fpstokts << " Vc: " << vc*fpstokts << endl;
}
else {
cout << "Failed to get Mach number for given Vc and altitude, Vc unchanged." << endl;
cout << "Please mail the set of initial conditions used to apeden@earthlink.net" << endl;
}
}
//******************************************************************************
void FGInitialCondition::SetVequivalentKtsIC(double tt) {
ve=tt*ktstofps;
lastSpeedSet=setve;
vt=ve*1/sqrt(fdmex->GetAtmosphere()->GetDensityRatio());
mach=vt/fdmex->GetAtmosphere()->GetSoundSpeed();
vc=calcVcas(mach);
}
//******************************************************************************
void FGInitialCondition::SetVgroundFpsIC(double tt) {
double ua,va,wa;
double vxz;
vg=tt;
lastSpeedSet=setvg;
vnorth = vg*cos(psi); veast = vg*sin(psi); vdown = 0;
calcUVWfromNED();
ua = u + uw; va = v + vw; wa = w + ww;
vt = sqrt( ua*ua + va*va + wa*wa );
alpha = beta = 0;
vxz = sqrt( u*u + w*w );
if( w != 0 ) alpha = atan2( w, u );
if( vxz != 0 ) beta = atan2( v, vxz );
mach=vt/fdmex->GetAtmosphere()->GetSoundSpeed();
vc=calcVcas(mach);
ve=vt*sqrt(fdmex->GetAtmosphere()->GetDensityRatio());
}
//******************************************************************************
void FGInitialCondition::SetVtrueFpsIC(double tt) {
vt=tt;
lastSpeedSet=setvt;
mach=vt/fdmex->GetAtmosphere()->GetSoundSpeed();
vc=calcVcas(mach);
ve=vt*sqrt(fdmex->GetAtmosphere()->GetDensityRatio());
}
//******************************************************************************
void FGInitialCondition::SetMachIC(double tt) {
mach=tt;
lastSpeedSet=setmach;
vt=mach*fdmex->GetAtmosphere()->GetSoundSpeed();
vc=calcVcas(mach);
ve=vt*sqrt(fdmex->GetAtmosphere()->GetDensityRatio());
//cout << "Vt: " << vt*fpstokts << " Vc: " << vc*fpstokts << endl;
}
//******************************************************************************
void FGInitialCondition::SetClimbRateFpmIC(double tt) {
SetClimbRateFpsIC(tt/60.0);
}
//******************************************************************************
void FGInitialCondition::SetClimbRateFpsIC(double tt) {
if(vt > 0.1) {
hdot=tt;
gamma=asin(hdot/vt);
sgamma=sin(gamma); cgamma=cos(gamma);
}
}
//******************************************************************************
void FGInitialCondition::SetFlightPathAngleRadIC(double tt) {
gamma=tt;
sgamma=sin(gamma); cgamma=cos(gamma);
getTheta();
hdot=vt*sgamma;
}
//******************************************************************************
void FGInitialCondition::SetAlphaRadIC(double tt) {
alpha=tt;
salpha=sin(alpha); calpha=cos(alpha);
getTheta();
}
//******************************************************************************
void FGInitialCondition::SetPitchAngleRadIC(double tt) {
theta=tt;
stheta=sin(theta); ctheta=cos(theta);
getAlpha();
}
//******************************************************************************
void FGInitialCondition::SetBetaRadIC(double tt) {
beta=tt;
sbeta=sin(beta); cbeta=cos(beta);
getTheta();
}
//******************************************************************************
void FGInitialCondition::SetRollAngleRadIC(double tt) {
phi=tt;
sphi=sin(phi); cphi=cos(phi);
getTheta();
}
//******************************************************************************
void FGInitialCondition::SetTrueHeadingRadIC(double tt) {
psi=tt;
spsi=sin(psi); cpsi=cos(psi);
calcWindUVW();
}
//******************************************************************************
void FGInitialCondition::SetUBodyFpsIC(double tt) {
u=tt;
vt=sqrt(u*u + v*v + w*w);
lastSpeedSet=setuvw;
}
//******************************************************************************
void FGInitialCondition::SetVBodyFpsIC(double tt) {
v=tt;
vt=sqrt(u*u + v*v + w*w);
lastSpeedSet=setuvw;
}
//******************************************************************************
void FGInitialCondition::SetWBodyFpsIC(double tt) {
w=tt;
vt=sqrt( u*u + v*v + w*w );
lastSpeedSet=setuvw;
}
//******************************************************************************
double FGInitialCondition::GetUBodyFpsIC(void) {
if(lastSpeedSet == setvg )
return u;
else
return vt*calpha*cbeta - uw;
}
//******************************************************************************
double FGInitialCondition::GetVBodyFpsIC(void) {
if( lastSpeedSet == setvg )
return v;
else {
return vt*sbeta - vw;
}
}
//******************************************************************************
double FGInitialCondition::GetWBodyFpsIC(void) {
if( lastSpeedSet == setvg )
return w;
else
return vt*salpha*cbeta -ww;
}
//******************************************************************************
void FGInitialCondition::SetWindNEDFpsIC(double wN, double wE, double wD ) {
wnorth = wN; weast = wE; wdown = wD;
lastWindSet = setwned;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
// positive from left
void FGInitialCondition::SetHeadWindKtsIC(double head){
whead=head*ktstofps;
lastWindSet=setwhc;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
void FGInitialCondition::SetCrossWindKtsIC(double cross){
wcross=cross*ktstofps;
lastWindSet=setwhc;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
void FGInitialCondition::SetWindDownKtsIC(double wD) {
wdown=wD;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
void FGInitialCondition::SetWindMagKtsIC(double mag) {
wmag=mag*ktstofps;
lastWindSet=setwmd;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
void FGInitialCondition::SetWindDirDegIC(double dir) {
wdir=dir*degtorad;
lastWindSet=setwmd;
calcWindUVW();
if(lastSpeedSet == setvg)
SetVgroundFpsIC(vg);
}
//******************************************************************************
void FGInitialCondition::calcWindUVW(void) {
switch(lastWindSet) {
case setwmd:
wnorth=wmag*cos(wdir);
weast=wmag*sin(wdir);
break;
case setwhc:
wnorth=whead*cos(psi) + wcross*cos(psi+M_PI/2);
weast=whead*sin(psi) + wcross*sin(psi+M_PI/2);
break;
}
uw=wnorth*ctheta*cpsi +
weast*ctheta*spsi -
wdown*stheta;
vw=wnorth*( sphi*stheta*cpsi - cphi*spsi ) +
weast*( sphi*stheta*spsi + cphi*cpsi ) +
wdown*sphi*ctheta;
ww=wnorth*(cphi*stheta*cpsi + sphi*spsi) +
weast*(cphi*stheta*spsi - sphi*cpsi) +
wdown*cphi*ctheta;
/* cout << "FGInitialCondition::calcWindUVW: wnorth, weast, wdown "
<< wnorth << ", " << weast << ", " << wdown << endl;
cout << "FGInitialCondition::calcWindUVW: theta, phi, psi "
<< theta << ", " << phi << ", " << psi << endl;
cout << "FGInitialCondition::calcWindUVW: uw, vw, ww "
<< uw << ", " << vw << ", " << ww << endl; */
}
//******************************************************************************
void FGInitialCondition::SetAltitudeFtIC(double tt) {
altitude=tt;
fdmex->GetPosition()->Seth(altitude);
fdmex->GetAtmosphere()->Run();
//lets try to make sure the user gets what they intended
switch(lastSpeedSet) {
case setned:
case setuvw:
case setvt:
SetVtrueKtsIC(vt*fpstokts);
break;
case setvc:
SetVcalibratedKtsIC(vc*fpstokts);
break;
case setve:
SetVequivalentKtsIC(ve*fpstokts);
break;
case setmach:
SetMachIC(mach);
break;
case setvg:
SetVgroundFpsIC(vg);
break;
}
}
//******************************************************************************
void FGInitialCondition::SetAltitudeAGLFtIC(double tt) {
fdmex->GetPosition()->SetDistanceAGL(tt);
altitude=fdmex->GetPosition()->Geth();
SetAltitudeFtIC(altitude);
}
//******************************************************************************
void FGInitialCondition::SetSeaLevelRadiusFtIC(double tt) {
sea_level_radius = tt;
}
//******************************************************************************
void FGInitialCondition::SetTerrainAltitudeFtIC(double tt) {
terrain_altitude=tt;
}
//******************************************************************************
void FGInitialCondition::calcUVWfromNED(void) {
u=vnorth*ctheta*cpsi +
veast*ctheta*spsi -
vdown*stheta;
v=vnorth*( sphi*stheta*cpsi - cphi*spsi ) +
veast*( sphi*stheta*spsi + cphi*cpsi ) +
vdown*sphi*ctheta;
w=vnorth*( cphi*stheta*cpsi + sphi*spsi ) +
veast*( cphi*stheta*spsi - sphi*cpsi ) +
vdown*cphi*ctheta;
}
//******************************************************************************
void FGInitialCondition::SetVnorthFpsIC(double tt) {
vnorth=tt;
calcUVWfromNED();
vt=sqrt(u*u + v*v + w*w);
lastSpeedSet=setned;
}
//******************************************************************************
void FGInitialCondition::SetVeastFpsIC(double tt) {
veast=tt;
calcUVWfromNED();
vt=sqrt(u*u + v*v + w*w);
lastSpeedSet=setned;
}
//******************************************************************************
void FGInitialCondition::SetVdownFpsIC(double tt) {
vdown=tt;
calcUVWfromNED();
vt=sqrt(u*u + v*v + w*w);
SetClimbRateFpsIC(-1*vdown);
lastSpeedSet=setned;
}
//******************************************************************************
bool FGInitialCondition::getMachFromVcas(double *Mach,double vcas) {
bool result=false;
double guess=1.5;
xlo=xhi=0;
xmin=0;xmax=50;
sfunc=&FGInitialCondition::calcVcas;
if(findInterval(vcas,guess)) {
if(solve(&mach,vcas))
result=true;
}
return result;
}
//******************************************************************************
bool FGInitialCondition::getAlpha(void) {
bool result=false;
double guess=theta-gamma;
xlo=xhi=0;
xmin=fdmex->GetAircraft()->GetAlphaCLMin();
xmax=fdmex->GetAircraft()->GetAlphaCLMax();
sfunc=&FGInitialCondition::GammaEqOfAlpha;
if(findInterval(0,guess)){
if(solve(&alpha,0)){
result=true;
salpha=sin(alpha);
calpha=cos(alpha);
}
}
calcWindUVW();
return result;
}
//******************************************************************************
bool FGInitialCondition::getTheta(void) {
bool result=false;
double guess=alpha+gamma;
xlo=xhi=0;
xmin=-89;xmax=89;
sfunc=&FGInitialCondition::GammaEqOfTheta;
if(findInterval(0,guess)){
if(solve(&theta,0)){
result=true;
stheta=sin(theta);
ctheta=cos(theta);
}
}
calcWindUVW();
return result;
}
//******************************************************************************
double FGInitialCondition::GammaEqOfTheta(double Theta) {
double a,b,c;
double sTheta,cTheta;
//theta=Theta; stheta=sin(theta); ctheta=cos(theta);
sTheta=sin(Theta); cTheta=cos(Theta);
calcWindUVW();
a=wdown + vt*calpha*cbeta + uw;
b=vt*sphi*sbeta + vw*sphi;
c=vt*cphi*salpha*cbeta + ww*cphi;
return vt*sgamma - ( a*sTheta - (b+c)*cTheta);
}
//******************************************************************************
double FGInitialCondition::GammaEqOfAlpha(double Alpha) {
double a,b,c;
double sAlpha,cAlpha;
sAlpha=sin(Alpha); cAlpha=cos(Alpha);
a=wdown + vt*cAlpha*cbeta + uw;
b=vt*sphi*sbeta + vw*sphi;
c=vt*cphi*sAlpha*cbeta + ww*cphi;
return vt*sgamma - ( a*stheta - (b+c)*ctheta );
}
//******************************************************************************
double FGInitialCondition::calcVcas(double Mach) {
double p=fdmex->GetAtmosphere()->GetPressure();
double psl=fdmex->GetAtmosphere()->GetPressureSL();
double rhosl=fdmex->GetAtmosphere()->GetDensitySL();
double pt,A,B,D,vcas;
if(Mach < 0) Mach=0;
if(Mach < 1) //calculate total pressure assuming isentropic flow
pt=p*pow((1 + 0.2*Mach*Mach),3.5);
else {
// shock in front of pitot tube, we'll assume its normal and use
// the Rayleigh Pitot Tube Formula, i.e. the ratio of total
// pressure behind the shock to the static pressure in front
//the normal shock assumption should not be a bad one -- most supersonic
//aircraft place the pitot probe out front so that it is the forward
//most point on the aircraft. The real shock would, of course, take
//on something like the shape of a rounded-off cone but, here again,
//the assumption should be good since the opening of the pitot probe
//is very small and, therefore, the effects of the shock curvature
//should be small as well. AFAIK, this approach is fairly well accepted
//within the aerospace community
B = 5.76*Mach*Mach/(5.6*Mach*Mach - 0.8);
// The denominator above is zero for Mach ~ 0.38, for which
// we'll never be here, so we're safe
D = (2.8*Mach*Mach-0.4)*0.4167;
pt = p*pow(B,3.5)*D;
}
A = pow(((pt-p)/psl+1),0.28571);
vcas = sqrt(7*psl/rhosl*(A-1));
//cout << "calcVcas: vcas= " << vcas*fpstokts << " mach= " << Mach << " pressure: " << pt << endl;
return vcas;
}
//******************************************************************************
bool FGInitialCondition::findInterval(double x,double guess) {
//void find_interval(inter_params &ip,eqfunc f,double y,double constant, int &flag){
int i=0;
bool found=false;
double flo,fhi,fguess;
double lo,hi,step;
step=0.1;
fguess=(this->*sfunc)(guess)-x;
lo=hi=guess;
do {
step=2*step;
lo-=step;
hi+=step;
if(lo < xmin) lo=xmin;
if(hi > xmax) hi=xmax;
i++;
flo=(this->*sfunc)(lo)-x;
fhi=(this->*sfunc)(hi)-x;
if(flo*fhi <=0) { //found interval with root
found=true;
if(flo*fguess <= 0) { //narrow interval down a bit
hi=lo+step; //to pass solver interval that is as
//small as possible
}
else if(fhi*fguess <= 0) {
lo=hi-step;
}
}
//cout << "findInterval: i=" << i << " Lo= " << lo << " Hi= " << hi << endl;
}
while((found == 0) && (i <= 100));
xlo=lo;
xhi=hi;
return found;
}
//******************************************************************************
bool FGInitialCondition::solve(double *y,double x)
{
double x1,x2,x3,f1,f2,f3,d,d0;
double eps=1E-5;
double const relax =0.9;
int i;
bool success=false;
//initializations
d=1;
x2 = 0;
x1=xlo;x3=xhi;
f1=(this->*sfunc)(x1)-x;
f3=(this->*sfunc)(x3)-x;
d0=fabs(x3-x1);
//iterations
i=0;
while ((fabs(d) > eps) && (i < 100)) {
d=(x3-x1)/d0;
x2 = x1-d*d0*f1/(f3-f1);
f2=(this->*sfunc)(x2)-x;
//cout << "solve x1,x2,x3: " << x1 << "," << x2 << "," << x3 << endl;
//cout << " " << f1 << "," << f2 << "," << f3 << endl;
if(fabs(f2) <= 0.001) {
x1=x3=x2;
} else if(f1*f2 <= 0.0) {
x3=x2;
f3=f2;
f1=relax*f1;
} else if(f2*f3 <= 0) {
x1=x2;
f1=f2;
f3=relax*f3;
}
//cout << i << endl;
i++;
}//end while
if(i < 100) {
success=true;
*y=x2;
}
//cout << "Success= " << success << " Vcas: " << vcas*fpstokts << " Mach: " << x2 << endl;
return success;
}
//******************************************************************************
double FGInitialCondition::GetWindDirDegIC(void) {
if(weast != 0.0)
return atan2(weast,wnorth)*radtodeg;
else if(wnorth > 0)
return 0.0;
else
return 180.0;
}
//******************************************************************************
bool FGInitialCondition::Load(string acpath, string acname, string rstfile)
{
string resetDef;
string token="";
double temp;
# ifndef macintosh
resetDef = acpath + "/" + acname + "/" + rstfile + ".xml";
# else
resetDef = acpath + ";" + acname + ";" + rstfile + ".xml";
# endif
FGConfigFile resetfile(resetDef);
if (!resetfile.IsOpen()) return false;
resetfile.GetNextConfigLine();
token = resetfile.GetValue();
if (token != string("initialize")) {
cerr << "The reset file " << resetDef
<< " does not appear to be a reset file" << endl;
return false;
}
resetfile.GetNextConfigLine();
resetfile >> token;
while (token != string("/initialize") && token != string("EOF")) {
if (token == "UBODY" ) { resetfile >> temp; SetUBodyFpsIC(temp); }
if (token == "VBODY" ) { resetfile >> temp; SetVBodyFpsIC(temp); }
if (token == "WBODY" ) { resetfile >> temp; SetWBodyFpsIC(temp); }
if (token == "LATITUDE" ) { resetfile >> temp; SetLatitudeDegIC(temp); }
if (token == "LONGITUDE" ) { resetfile >> temp; SetLongitudeDegIC(temp); }
if (token == "PHI" ) { resetfile >> temp; SetRollAngleDegIC(temp); }
if (token == "THETA" ) { resetfile >> temp; SetPitchAngleDegIC(temp); }
if (token == "PSI" ) { resetfile >> temp; SetTrueHeadingDegIC(temp); }
if (token == "ALPHA" ) { resetfile >> temp; SetAlphaDegIC(temp); }
if (token == "BETA" ) { resetfile >> temp; SetBetaDegIC(temp); }
if (token == "GAMMA" ) { resetfile >> temp; SetFlightPathAngleDegIC(temp); }
if (token == "ROC" ) { resetfile >> temp; SetClimbRateFpmIC(temp); }
if (token == "ALTITUDE" ) { resetfile >> temp; SetAltitudeFtIC(temp); }
if (token == "WINDDIR" ) { resetfile >> temp; SetWindDirDegIC(temp); }
if (token == "VWIND" ) { resetfile >> temp; SetWindMagKtsIC(temp); }
if (token == "HWIND" ) { resetfile >> temp; SetHeadWindKtsIC(temp); }
if (token == "XWIND" ) { resetfile >> temp; SetCrossWindKtsIC(temp); }
if (token == "VC" ) { resetfile >> temp; SetVcalibratedKtsIC(temp); }
if (token == "MACH" ) { resetfile >> temp; SetMachIC(temp); }
if (token == "VGROUND" ) { resetfile >> temp; SetVgroundKtsIC(temp); }
resetfile >> token;
}
fdmex->RunIC(this);
return true;
}
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