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flightgear/src/FDM/JSBSim/FGTrim.cpp
2000-10-02 23:07:30 +00:00

504 lines
18 KiB
C++

/*******************************************************************************
Header: FGTrim.cpp
Author: Tony Peden
Date started: 9/8/99
--------- 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
--------------------------------------------------------------------------------
9/8/99 TP Created
FUNCTIONAL DESCRIPTION
--------------------------------------------------------------------------------
This class takes the given set of IC's and finds the angle of attack, elevator,
and throttle setting required to fly steady level. This is currently for in-air
conditions only. It is implemented using an iterative, one-axis-at-a-time
scheme. */
// !!!!!!! BEWARE ALL YE WHO ENTER HERE !!!!!!!
/*******************************************************************************
INCLUDES
*******************************************************************************/
#include <stdlib.h>
#include "FGFDMExec.h"
#include "FGAtmosphere.h"
#include "FGInitialCondition.h"
#include "FGTrim.h"
#include "FGAircraft.h"
/*******************************************************************************/
FGTrim::FGTrim(FGFDMExec *FDMExec,FGInitialCondition *FGIC, TrimMode tt ) {
N=Nsub=0;
max_iterations=60;
max_sub_iterations=100;
Tolerance=1E-3;
A_Tolerance = Tolerance / 10;
Debug=0;
fdmex=FDMExec;
fgic=FGIC;
total_its=0;
trimudot=true;
gamma_fallback=true;
axis_count=0;
mode=tt;
xlo=xhi=alo=ahi;
switch(mode) {
case tFull:
cout << " Full 6-DOF Trim" << endl;
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tWdot,tAlpha,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tUdot,tThrottle,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tQdot,tPitchTrim,A_Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tVdot,tPhi,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tPdot,tAileron,A_Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tRdot,tRudder,A_Tolerance));
break;
case tLongitudinal:
cout << " Longitudinal Trim" << endl;
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tWdot,tAlpha,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tUdot,tThrottle,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tQdot,tPitchTrim,A_Tolerance));
break;
case tGround:
cout << " Ground Trim" << endl;
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tWdot,tAltAGL,Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tQdot,tTheta,A_Tolerance));
TrimAxes.push_back(new FGTrimAxis(fdmex,fgic,tPdot,tPhi,A_Tolerance));
break;
}
//cout << "NumAxes: " << TrimAxes.size() << endl;
NumAxes=TrimAxes.size();
sub_iterations=new float[NumAxes];
successful=new float[NumAxes];
solution=new bool[NumAxes];
current_axis=0;
}
/******************************************************************************/
FGTrim::~FGTrim(void) {
for(current_axis=0; current_axis<NumAxes; current_axis++) {
delete TrimAxes[current_axis];
}
delete[] sub_iterations;
delete[] successful;
delete[] solution;
}
/******************************************************************************/
void FGTrim::TrimStats() {
char out[80];
int run_sum=0;
cout << endl << " Trim Statistics: " << endl;
cout << " Total Iterations: " << total_its << endl;
if(total_its > 0) {
cout << " Sub-iterations:" << endl;
for(current_axis=0; current_axis<NumAxes; current_axis++) {
run_sum+=TrimAxes[current_axis]->GetRunCount();
sprintf(out," %5s: %3.0f average: %5.2f successful: %3.0f stability: %5.2f\n",
TrimAxes[current_axis]->GetAccelName().c_str(),
sub_iterations[current_axis],
sub_iterations[current_axis]/float(total_its),
successful[current_axis],
TrimAxes[current_axis]->GetAvgStability() );
cout << out;
}
cout << " Run Count: " << run_sum << endl;
}
}
/******************************************************************************/
void FGTrim::Report(void) {
cout << " Trim Results: " << endl;
for(current_axis=0; current_axis<NumAxes; current_axis++)
TrimAxes[current_axis]->AxisReport();
}
/******************************************************************************/
void FGTrim::ReportState(void) {
char out[80], flap[10], gear[10];
cout << endl << " JSBSim State" << endl;
sprintf(out," Weight: %7.0f lbs. CG: %5.1f, %5.1f, %5.1f inches\n",
fdmex->GetAircraft()->GetWeight(),
fdmex->GetAircraft()->GetXYZcg()(1),
fdmex->GetAircraft()->GetXYZcg()(2),
fdmex->GetAircraft()->GetXYZcg()(3) );
cout << out;
if( fdmex->GetFCS()->GetDfPos() <= 0.01)
sprintf(flap,"Up");
else
sprintf(flap,"%2.0f",fdmex->GetFCS()->GetDfPos());
if(fdmex->GetAircraft()->GetGearUp() == true)
sprintf(gear,"Up");
else
sprintf(gear,"Down");
sprintf(out, " Flaps: %3s Gear: %4s\n",flap,gear);
cout << out;
sprintf(out, " Speed: %4.0f KCAS Mach: %5.2f Altitude: %7.0f ft.\n",
fdmex->GetAuxiliary()->GetVcalibratedKTS(),
fdmex->GetState()->GetParameter(FG_MACH),
fdmex->GetPosition()->Geth() );
cout << out;
sprintf(out, " Angle of Attack: %6.2f deg Pitch Angle: %6.2f deg\n",
fdmex->GetState()->GetParameter(FG_ALPHA)*RADTODEG,
fdmex->GetRotation()->Gettht()*RADTODEG );
cout << out;
sprintf(out, " Flight Path Angle: %6.2f deg Climb Rate: %5.0f ft/min\n",
fdmex->GetPosition()->GetGamma()*RADTODEG,
fdmex->GetPosition()->Gethdot()*60 );
cout << out;
sprintf(out, " Normal Load Factor: %4.2f g's Pitch Rate: %5.2f deg/s\n",
fdmex->GetAircraft()->GetNlf(),
fdmex->GetState()->GetParameter(FG_PITCHRATE)*RADTODEG );
cout << out;
sprintf(out, " Heading: %3.0f deg true Sideslip: %5.2f deg\n",
fdmex->GetRotation()->Getpsi()*RADTODEG,
fdmex->GetState()->GetParameter(FG_BETA)*RADTODEG );
cout << out;
sprintf(out, " Bank Angle: %3.0f deg\n",
fdmex->GetRotation()->Getphi()*RADTODEG );
cout << out;
sprintf(out, " Elevator: %5.2f deg Left Aileron: %5.2f deg Rudder: %5.2f deg\n",
fdmex->GetState()->GetParameter(FG_ELEVATOR_POS)*RADTODEG,
fdmex->GetState()->GetParameter(FG_AILERON_POS)*RADTODEG,
fdmex->GetState()->GetParameter(FG_RUDDER_POS)*RADTODEG );
cout << out;
sprintf(out, " Throttle: %5.2f%c\n",
fdmex->GetFCS()->GetThrottlePos(0),'%' );
cout << out;
}
/******************************************************************************/
bool FGTrim::DoTrim(void) {
trim_failed=false;
for(int i=0;i < fdmex->GetAircraft()->GetNumGearUnits();i++){
fdmex->GetAircraft()->GetGearUnit(i)->SetReport(false);
}
fdmex->GetOutput()->Disable();
//clear the sub iterations counts & zero out the controls
for(current_axis=0;current_axis<NumAxes;current_axis++) {
//cout << current_axis << " " << TrimAxes[current_axis]->GetAccelName()
//<< " " << TrimAxes[current_axis]->GetControlName()<< endl;
xlo=TrimAxes[current_axis]->GetControlMin();
xhi=TrimAxes[current_axis]->GetControlMax();
TrimAxes[current_axis]->SetControl((xlo+xhi)/2);
TrimAxes[current_axis]->Run();
//TrimAxes[current_axis]->AxisReport();
sub_iterations[current_axis]=0;
successful[current_axis]=0;
solution[current_axis]=false;
}
do {
axis_count=0;
for(current_axis=0;current_axis<NumAxes;current_axis++) {
Nsub=0;
if(!solution[current_axis]) {
if(checkLimits()) {
solution[current_axis]=true;
solve();
}
} else if(findInterval()) {
solve();
} else {
solution[current_axis]=false;
}
sub_iterations[current_axis]+=Nsub;
}
for(current_axis=0;current_axis<NumAxes;current_axis++) {
//these checks need to be done after all the axes have run
if(Debug > 0) TrimAxes[current_axis]->AxisReport();
if(TrimAxes[current_axis]->InTolerance()) {
axis_count++;
successful[current_axis]++;
}
}
if((axis_count == NumAxes-1) && (NumAxes > 1)) {
//cout << NumAxes-1 << " out of " << NumAxes << "!" << endl;
//At this point we can check the input limits of the failed axis
//and declare the trim failed if there is no sign change. If there
//is, keep going until success or max iteration count
//Oh, well: two out of three ain't bad
for(current_axis=0;current_axis<NumAxes;current_axis++) {
//these checks need to be done after all the axes have run
if(!TrimAxes[current_axis]->InTolerance()) {
if(!checkLimits()) {
// special case this for now -- if other cases arise proper
// support can be added to FGTrimAxis
if( (gamma_fallback) &&
(TrimAxes[current_axis]->GetAccelType() == tUdot) &&
(TrimAxes[current_axis]->GetControlType() == tThrottle)) {
cout << " Can't trim udot with throttle, trying flight"
<< " path angle. (" << N << ")" << endl;
if(TrimAxes[current_axis]->GetAccel() > 0)
TrimAxes[current_axis]->SetControlToMin();
else
TrimAxes[current_axis]->SetControlToMax();
TrimAxes[current_axis]->Run();
delete TrimAxes[current_axis];
TrimAxes[current_axis]=new FGTrimAxis(fdmex,fgic,tUdot,
tGamma,Tolerance);
} else {
cout << " Sorry, " << TrimAxes[current_axis]->GetAccelName()
<< " doesn't appear to be trimmable" << endl;
//total_its=k;
trim_failed=true; //force the trim to fail
} //gamma_fallback
}
} //solution check
} //for loop
} //all-but-one check
N++;
if(N > max_iterations)
trim_failed=true;
} while((axis_count < NumAxes) && (!trim_failed));
if((!trim_failed) && (axis_count >= NumAxes)) {
total_its=N;
cout << endl << " Trim successful" << endl;
} else {
total_its=N;
cout << endl << " Trim failed" << endl;
}
for(int i=0;i < fdmex->GetAircraft()->GetNumGearUnits();i++){
fdmex->GetAircraft()->GetGearUnit(i)->SetReport(true);
}
fdmex->GetOutput()->Enable();
return !trim_failed;
}
/******************************************************************************/
bool FGTrim::solve(void) {
float x1,x2,x3,f1,f2,f3,d,d0;
const float relax =0.9;
float eps=TrimAxes[current_axis]->GetSolverEps();
x1=x2=x3=0;
d=1;
bool success=false;
//initializations
if( solutionDomain != 0) {
/* if(ahi > alo) { */
x1=xlo;f1=alo;
x3=xhi;f3=ahi;
/* } else {
x1=xhi;f1=ahi;
x3=xlo;f3=alo;
} */
d0=fabs(x3-x1);
//iterations
//max_sub_iterations=TrimAxes[current_axis]->GetIterationLimit();
while (!TrimAxes[current_axis]->InTolerance() && (fabs(d) > eps)
&& (Nsub < max_sub_iterations)) {
Nsub++;
d=(x3-x1)/d0;
x2=x1-d*d0*f1/(f3-f1);
TrimAxes[current_axis]->SetControl(x2);
TrimAxes[current_axis]->Run();
f2=TrimAxes[current_axis]->GetAccel();
if(Debug > 1) {
cout << "FGTrim::solve Nsub,x1,x2,x3: " << Nsub << ", " << x1
<< ", " << x2 << ", " << x3 << endl;
cout << " " << f1 << ", " << f2 << ", " << f3 << endl;
}
if(f1*f2 <= 0.0) {
x3=x2;
f3=f2;
f1=relax*f1;
//cout << "Solution is between x1 and x2" << endl;
}
else if(f2*f3 <= 0.0) {
x1=x2;
f1=f2;
f3=relax*f3;
//cout << "Solution is between x2 and x3" << endl;
}
//cout << i << endl;
}//end while
if(Nsub < max_sub_iterations) success=true;
}
return success;
}
/******************************************************************************/
/*
produces an interval (xlo..xhi) on one side or the other of the current
control value in which a solution exists. This domain is, hopefully,
smaller than xmin..0 or 0..xmax and the solver will require fewer iterations
to find the solution. This is, hopefully, more efficient than having the
solver start from scratch every time. Maybe it isn't though...
This tries to take advantage of the idea that the changes from iteration to
iteration will be small after the first one or two top-level iterations.
assumes that changing the control will a produce significant change in the
accel i.e. checkLimits() has already been called.
if a solution is found above the current control, the function returns true
and xlo is set to the current control, xhi to the interval max it found, and
solutionDomain is set to 1.
if the solution lies below the current control, then the function returns
true and xlo is set to the interval min it found and xmax to the current
control. if no solution is found, then the function returns false.
in all cases, alo=accel(xlo) and ahi=accel(xhi) after the function exits.
no assumptions about the state of the sim after this function has run
can be made.
*/
bool FGTrim::findInterval(void) {
bool found=false;
float step;
float current_control=TrimAxes[current_axis]->GetControl();
float current_accel=TrimAxes[current_axis]->GetAccel();;
float xmin=TrimAxes[current_axis]->GetControlMin();
float xmax=TrimAxes[current_axis]->GetControlMax();
float lastxlo,lastxhi,lastalo,lastahi;
step=0.025*fabs(xmax);
xlo=xhi=current_control;
alo=ahi=current_accel;
lastxlo=xlo;lastxhi=xhi;
lastalo=alo;lastahi=ahi;
do {
Nsub++;
step*=2;
xlo-=step;
if(xlo < xmin) xlo=xmin;
xhi+=step;
if(xhi > xmax) xhi=xmax;
TrimAxes[current_axis]->SetControl(xlo);
TrimAxes[current_axis]->Run();
alo=TrimAxes[current_axis]->GetAccel();
TrimAxes[current_axis]->SetControl(xhi);
TrimAxes[current_axis]->Run();
ahi=TrimAxes[current_axis]->GetAccel();
if(fabs(ahi-alo) <= TrimAxes[current_axis]->GetTolerance()) continue;
if(alo*ahi <=0) { //found interval with root
found=true;
if(alo*current_accel <= 0) { //narrow interval down a bit
solutionDomain=-1;
xhi=lastxlo;
ahi=lastalo;
//xhi=current_control;
//ahi=current_accel;
} else {
solutionDomain=1;
xlo=lastxhi;
alo=lastahi;
//xlo=current_control;
//alo=current_accel;
}
}
lastxlo=xlo;lastxhi=xhi;
lastalo=alo;lastahi=ahi;
if( !found && xlo==xmin && xhi==xmax ) continue;
if(Debug > 1)
cout << "FGTrim::findInterval: Nsub=" << Nsub << " Lo= " << xlo
<< " Hi= " << xhi << " alo*ahi: " << alo*ahi << endl;
} while(!found && (Nsub <= max_sub_iterations) );
return found;
}
/******************************************************************************/
//checks to see which side of the current control value the solution is on
//and sets solutionDomain accordingly:
// 1 if solution is between the current and max
// -1 if solution is between the min and current
// 0 if there is no solution
//
//if changing the control produces no significant change in the accel then
//solutionDomain is set to zero and the function returns false
//if a solution is found, then xlo and xhi are set so that they bracket
//the solution, alo is set to accel(xlo), and ahi is set to accel(xhi)
//if there is no change or no solution then xlo=xmin, alo=accel(xmin) and
//xhi=xmax and ahi=accel(xmax)
//in all cases the sim is left such that the control=xmax and accel=ahi
bool FGTrim::checkLimits(void) {
bool solutionExists;
float current_control=TrimAxes[current_axis]->GetControl();
float current_accel=TrimAxes[current_axis]->GetAccel();
xlo=TrimAxes[current_axis]->GetControlMin();
xhi=TrimAxes[current_axis]->GetControlMax();
TrimAxes[current_axis]->SetControl(xlo);
TrimAxes[current_axis]->Run();
alo=TrimAxes[current_axis]->GetAccel();
TrimAxes[current_axis]->SetControl(xhi);
TrimAxes[current_axis]->Run();
ahi=TrimAxes[current_axis]->GetAccel();
if(Debug > 1)
cout << "checkLimits() xlo,xhi,alo,ahi: " << xlo << ", " << xhi << ", "
<< alo << ", " << ahi << endl;
solutionDomain=0;
solutionExists=false;
if(fabs(ahi-alo) > TrimAxes[current_axis]->GetTolerance()) {
if(alo*current_accel < 0) {
solutionExists=true;
solutionDomain=-1;
xhi=current_control;
ahi=current_accel;
} else if(current_accel*ahi < 0){
solutionExists=true;
solutionDomain=1;
xlo=current_control;
alo=current_accel;
}
}
TrimAxes[current_axis]->SetControl(current_control);
TrimAxes[current_axis]->Run();
return solutionExists;
}
//YOU WERE WARNED, BUT YOU DID IT ANYWAY.