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flightgear/src/FDM/LaRCsimIC.cxx
2001-03-26 18:22:31 +00:00

388 lines
9.4 KiB
C++

/*******************************************************************************
Header: LaRCsimIC.cxx
Author: Tony Peden
Date started: 10/9/99
------------- 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.
*/
#include <simgear/compiler.h>
#include <math.h>
#include STL_IOSTREAM
#include "FDM/LaRCsimIC.hxx"
#include <FDM/LaRCsim/ls_cockpit.h>
#include <FDM/LaRCsim/ls_generic.h>
#include <FDM/LaRCsim/ls_interface.h>
#include <FDM/LaRCsim/atmos_62.h>
#include <FDM/LaRCsim/ls_constants.h>
#include <FDM/LaRCsim/ls_geodesy.h>
#if !defined(SG_HAVE_NATIVE_SGI_COMPILERS)
SG_USING_STD(cout);
SG_USING_STD(endl);
#endif
LaRCsimIC::LaRCsimIC(void) {
vt=vtg=vw=vc=ve=0;
mach=0;
alpha=beta=gamma=0;
theta=phi=psi=0;
altitude=runway_altitude=hdot=alt_agl=0;
latitude_gd=latitude_gc=longitude=0;
u=v=w=0;
vnorth=veast=vdown=0;
vnorthwind=veastwind=vdownwind=0;
lastSpeedSet=lssetvt;
lastAltSet=lssetasl;
get_atmosphere();
ls_geod_to_geoc( latitude_gd,altitude,&sea_level_radius,&latitude_gc);
}
LaRCsimIC::~LaRCsimIC(void) {}
void LaRCsimIC::get_atmosphere(void) {
Altitude=altitude; //set LaRCsim variable
ls_atmos(Altitude, &density_ratio, &soundspeed, &T, &p);
rho=density_ratio*SEA_LEVEL_DENSITY;
}
void LaRCsimIC::SetVcalibratedKtsIC( SCALAR tt) {
vc=tt*KTS_TO_FPS;
lastSpeedSet=lssetvc;
vt=sqrt(1/density_ratio*vc*vc);
}
void LaRCsimIC::SetVtrueFpsIC( SCALAR tt) {
vt=tt;
lastSpeedSet=lssetvt;
}
void LaRCsimIC::SetMachIC( SCALAR tt) {
mach=tt;
vt=mach*soundspeed;
lastSpeedSet=lssetmach;
}
void LaRCsimIC::SetVequivalentKtsIC(SCALAR tt) {
ve=tt*KTS_TO_FPS;
lastSpeedSet=lssetve;
vt=sqrt(SEA_LEVEL_DENSITY/rho)*ve;
}
void LaRCsimIC::SetClimbRateFpmIC( SCALAR tt) {
SetClimbRateFpsIC(tt/60.0);
}
void LaRCsimIC::SetClimbRateFpsIC( SCALAR tt) {
vtg=vt+vw;
cout << "vtg: " << vtg << endl;
if(vtg > 0.1) {
hdot = tt - vdownwind;
gamma=asin(hdot/vtg);
getTheta();
vdown=-1*hdot;
cout << "hdot: " << hdot << endl;
cout << "gamma: " << gamma*SGD_RADIANS_TO_DEGREES << endl;
cout << "vdown: " << vdown << endl;
}
}
void LaRCsimIC::SetFlightPathAngleRadIC( SCALAR tt) {
gamma=tt;
getTheta();
vtg=vt+vw;
hdot=vtg*sin(tt);
cout << "hdot: " << hdot << endl;
vdown=-1*hdot;
}
void LaRCsimIC::SetPitchAngleRadIC(SCALAR tt) {
if(alt_agl < (DEFAULT_AGL_ALT + 0.1) || vt < 10 )
theta=DEFAULT_PITCH_ON_GROUND;
else
theta=tt;
getAlpha();
}
void LaRCsimIC::SetUVWFpsIC(SCALAR vu, SCALAR vv, SCALAR vw) {
u=vu; v=vv; w=vw;
vt=sqrt(u*u+v*v+w*w);
lastSpeedSet=lssetuvw;
}
void LaRCsimIC::SetVNEDAirmassFpsIC(SCALAR north, SCALAR east, SCALAR down ) {
vnorthwind=north; veastwind=east; vdownwind=down;
vw=sqrt(vnorthwind*vnorthwind + veastwind*veastwind + vdownwind*vdownwind);
vtg=vt+vw;
SetClimbRateFpsIC(-1*(vdown+vdownwind));
}
void LaRCsimIC::SetAltitudeFtIC( SCALAR tt) {
if(tt > (runway_altitude + DEFAULT_AGL_ALT)) {
altitude=tt;
} else {
altitude=runway_altitude + DEFAULT_AGL_ALT;
alt_agl=DEFAULT_AGL_ALT;
theta=DEFAULT_PITCH_ON_GROUND;
}
lastAltSet=lssetasl;
get_atmosphere();
//lets try to make sure the user gets what they intended
switch(lastSpeedSet) {
case lssetned:
calcVtfromNED();
break;
case lssetuvw:
case lssetvt:
SetVtrueFpsIC(vt);
break;
case lssetvc:
SetVcalibratedKtsIC(vc*V_TO_KNOTS);
break;
case lssetve:
SetVequivalentKtsIC(ve*V_TO_KNOTS);
break;
case lssetmach:
SetMachIC(mach);
break;
}
}
void LaRCsimIC::SetAltitudeAGLFtIC( SCALAR tt) {
alt_agl=tt;
lastAltSet=lssetagl;
altitude=runway_altitude + alt_agl;
}
void LaRCsimIC::SetRunwayAltitudeFtIC( SCALAR tt) {
runway_altitude=tt;
if(lastAltSet == lssetagl)
altitude = runway_altitude + alt_agl;
}
void LaRCsimIC::calcVtfromNED(void) {
//take the earth's rotation out of veast first
//float veastner = veast- OMEGA_EARTH*sea_level_radius*cos( latitude_gd );
float veastner=veast;
u = (vnorth - vnorthwind)*cos(theta)*cos(psi) +
(veastner - veastwind)*cos(theta)*sin(psi) -
(vdown - vdownwind)*sin(theta);
v = (vnorth - vnorthwind)*(sin(phi)*sin(theta)*cos(psi) - cos(phi)*sin(psi)) +
(veastner - veastwind)*(sin(phi)*sin(theta)*sin(psi) + cos(phi)*cos(psi)) +
(vdown - vdownwind)*sin(phi)*cos(theta);
w = (vnorth - vnorthwind)*(cos(phi)*sin(theta)*cos(psi) + sin(phi)*sin(psi)) +
(veastner - veastwind)*(cos(phi)*sin(theta)*sin(psi) - sin(phi)*cos(psi)) +
(vdown - vdownwind)*cos(phi)*cos(theta);
vt = sqrt(u*u + v*v + w*w);
}
void LaRCsimIC::calcNEDfromVt(void) {
float veastner;
//get the body components of vt
u = GetUBodyFpsIC();
v = GetVBodyFpsIC();
w = GetWBodyFpsIC();
//transform them to local axes and add on the wind components
vnorth = u*cos(theta)*cos(psi) +
v*(sin(phi)*sin(theta)*cos(psi) - cos(phi)*sin(psi)) +
w*(cos(phi)*sin(theta)*cos(psi) + sin(phi)*sin(psi)) +
vnorthwind;
//need to account for the earth's rotation here
veastner = u*cos(theta)*sin(psi) +
v*(sin(phi)*sin(theta)*sin(psi) + cos(phi)*cos(psi)) +
w*(cos(phi)*sin(theta)*sin(psi) - sin(phi)*cos(psi)) +
veastwind;
veast = veastner;
//veast = veastner + OMEGA_EARTH*sea_level_radius*cos( latitude_gd );
vdown = u*sin(theta) +
v*sin(phi)*cos(theta) +
w*cos(phi)*cos(theta) +
vdownwind;
}
void LaRCsimIC::SetVNEDFpsIC( SCALAR north, SCALAR east, SCALAR down) {
vnorth=north;
veast=east;
vdown=down;
SetClimbRateFpsIC(-1*vdown);
lastSpeedSet=lssetned;
calcVtfromNED();
}
void LaRCsimIC::SetLatitudeGDRadIC(SCALAR tt) {
latitude_gd=tt;
ls_geod_to_geoc(latitude_gd,altitude,&sea_level_radius, &latitude_gc);
}
bool LaRCsimIC::getAlpha(void) {
bool result=false;
float guess=theta-gamma;
xlo=xhi=0;
xmin=-89;
xmax=89;
sfunc=&LaRCsimIC::GammaEqOfAlpha;
if(findInterval(0,guess)){
if(solve(&alpha,0)){
result=true;
}
}
return result;
}
bool LaRCsimIC::getTheta(void) {
bool result=false;
float guess=alpha+gamma;
xlo=xhi=0;
xmin=-89;xmax=89;
sfunc=&LaRCsimIC::GammaEqOfTheta;
if(findInterval(0,guess)){
if(solve(&theta,0)){
result=true;
}
}
return result;
}
SCALAR LaRCsimIC::GammaEqOfTheta( SCALAR theta_arg) {
SCALAR a,b,c;
a=cos(alpha)*cos(beta)*sin(theta_arg);
b=sin(beta)*sin(phi);
c=sin(alpha)*cos(beta)*cos(phi);
return sin(gamma)-a+(b+c)*cos(theta_arg);
}
SCALAR LaRCsimIC::GammaEqOfAlpha( SCALAR alpha_arg) {
float a,b,c;
a=cos(alpha_arg)*cos(beta)*sin(theta);
b=sin(beta)*sin(phi);
c=sin(alpha_arg)*cos(beta)*cos(phi);
return sin(gamma)-a+(b+c)*cos(theta);
}
bool LaRCsimIC::findInterval( SCALAR x,SCALAR guess) {
//void find_interval(inter_params &ip,eqfunc f,float y,float constant, int &flag){
int i=0;
bool found=false;
float flo,fhi,fguess;
float 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 LaRCsimIC::solve( SCALAR *y,SCALAR x) {
float x1,x2,x3,f1,f2,f3,d,d0;
float eps=1E-5;
float const relax =0.9;
int i;
bool success=false;
//initializations
d=1;
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*V_TO_KNOTS << " Mach: " << x2 << endl;
return success;
}