/******************************************************************************* 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 #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 0) { cout << " Sub-iterations:" << endl; for(current_axis=0; current_axisGetRunCount(); 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_axisAxisReport(); } /******************************************************************************/ 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_axisGetAccelName() //<< " " << 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 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_axisInTolerance()) { 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.