fly/flightgear
1
0
Fork 0
Code Activity

YASim: add variables for solver parameters

Browse source
This commit is contained in:
Henning Stahlke 2018-02-03 01:38:24 +01:00
parent 12bf5cdfa6
commit c985c19735
4 changed files with 75 additions and 43 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

83
src/FDM/YASim/Airplane.cpp
View file

@ -22,18 +22,6 @@ static const char* DEF_PROP_ELEVATOR_TRIM = "/controls/flight/elevator-trim";
// gadgets
inline float abs(float f) { return f<0 ? -f : f; }
// Solver threshold. How close to the solution are we trying
// to get? Trying too hard can result in oscillations about
// the correct solution, which is bad. Stick this in as a
// compile time constant for now, and consider making it
// settable per-model.
const float STHRESH = 1;
// How slowly do we change values in the solver. Too slow, and
// the solution converges very slowly. Too fast, and it can
// oscillate.
const float SOLVE_TWEAK = 0.3226;
Airplane::Airplane()
{
_approachConfig.isApproach = true;
@ -522,7 +510,7 @@ void Airplane::compileContactPoints()
}
}
void Airplane::compile()
void Airplane::compile(bool verbose)
{
RigidBody* body = _model.getBody();
int firstMass = body->numMasses();
@ -650,12 +638,12 @@ void Airplane::compile()
solveGear();
calculateCGHardLimits();
if(_wing && _tail) solveAirplane();
if(_wing && _tail) solveAirplane(verbose);
else
{
// The rotor(s) mass:
compileRotorgear();
solveHelicopter();
solveHelicopter(verbose);
}
// Do this after solveGear, because it creates "gear" objects that
@ -810,7 +798,7 @@ void Airplane::runConfig(Config &cfg)
/// Used only in solveAirplane() and solveHelicopter(), not at runtime
void Airplane::applyDragFactor(float factor)
{
float applied = Math::pow(factor, SOLVE_TWEAK);
float applied = Math::pow(factor, _solverDelta);
_dragFactor *= applied;
if(_wing)
_wing->multiplyDragCoefficient(applied);
@ -856,7 +844,7 @@ void Airplane::applyDragFactor(float factor)
/// change lift coefficient cz in surfaces
void Airplane::applyLiftRatio(float factor)
{
float applied = Math::pow(factor, SOLVE_TWEAK);
float applied = Math::pow(factor, _solverDelta);
_liftRatio *= applied;
if(_wing)
_wing->multiplyLiftRatio(applied);
@ -895,7 +883,7 @@ float Airplane::_getLift(Config &cfg)
return cfg.weight * tmp[2];
}
void Airplane::solveAirplane()
void Airplane::solveAirplane(bool verbose)
{
static const float ARCMIN = 0.0002909f;
@ -913,14 +901,18 @@ void Airplane::solveAirplane()
_tailIncidence = new ControlSetting;
_tailIncidenceCopy = new ControlSetting;
}
if (verbose) {
fprintf(stdout,"i\tdAoa\tdTail\tcl0\tcp1\n");
}
while(1) {
if(_solutionIterations++ > SOLVER_MAX_ITERATIONS) {
if(_solutionIterations++ > _solverMaxIterations) {
_failureMsg = "Solution failed to converge!";
return;
}
// Run an iteration at cruise, and extract the needed numbers:
runConfig(_cruiseConfig);
_model.getThrust(tmp);
float thrust = tmp[0] + _cruiseConfig.weight * Math::sin(_cruiseConfig.glideAngle) * 9.81;
@ -985,8 +977,8 @@ void Airplane::solveAirplane()
applyLiftRatio(liftFactor);
// DON'T do the following until the above are sane
if(normFactor(dragFactor) > STHRESH*1.0001
|| normFactor(liftFactor) > STHRESH*1.0001)
if(normFactor(dragFactor) > _solverThreshold*1.0001
|| normFactor(liftFactor) > _solverThreshold*1.0001)
{
continue;
}
@ -994,24 +986,31 @@ void Airplane::solveAirplane()
// OK, now we can adjust the minor variables:
float aoaDelta = -clift0 * (ARCMIN/(clift1-clift0));
float tailDelta = -cpitch0 * (ARCMIN/(cpitch1-cpitch0));
_cruiseConfig.aoa += SOLVE_TWEAK*aoaDelta;
_tailIncidence->val += SOLVE_TWEAK*tailDelta;
if (verbose) {
fprintf(stdout,"%4d\t%f\t%f\t%f\t%f\n", _solutionIterations, aoaDelta, tailDelta, clift0, cpitch1);
}
_cruiseConfig.aoa += _solverDelta*aoaDelta;
_tailIncidence->val += _solverDelta*tailDelta;
_cruiseConfig.aoa = Math::clamp(_cruiseConfig.aoa, -0.175f, 0.175f);
_tailIncidence->val = Math::clamp(_tailIncidence->val, -0.175f, 0.175f);
if(abs(xforce/_cruiseConfig.weight) < STHRESH*0.0001 &&
abs(alift/_approachConfig.weight) < STHRESH*0.0001 &&
abs(aoaDelta) < STHRESH*.000017 &&
abs(tailDelta) < STHRESH*.000017)
if(abs(xforce/_cruiseConfig.weight) < _solverThreshold*0.0001 &&
abs(alift/_approachConfig.weight) < _solverThreshold*0.0001 &&
abs(aoaDelta) < _solverThreshold*.000017 &&
abs(tailDelta) < _solverThreshold*.000017)
{
float elevDelta = -apitch0 * (ELEVDIDDLE/(apitch1-apitch0));
if (verbose) {
fprintf(stdout,"%4d dElev %f, ap0 %f,ap1 %f \n", _solutionIterations, elevDelta, apitch0, apitch1);
}
// If this finaly value is OK, then we're all done
if(abs(elevDelta) < STHRESH*0.0001)
if(abs(elevDelta) < _solverThreshold*0.0001)
break;
// Otherwise, adjust and do the next iteration
_approachElevator->val += SOLVE_TWEAK * elevDelta;
_approachElevator->val += _solverDelta * elevDelta;
if(abs(_approachElevator->val) > 1) {
_failureMsg = "Insufficient elevator to trim for approach.";
break;
@ -1040,7 +1039,7 @@ void Airplane::solveAirplane()
}
}
void Airplane::solveHelicopter()
void Airplane::solveHelicopter(bool verbose)
{
_solutionIterations = 0;
_failureMsg = 0;
@ -1048,16 +1047,16 @@ void Airplane::solveHelicopter()
{
Rotorgear* rg = getRotorgear();
applyDragFactor(Math::pow(rg->getYasimDragFactor()/1000,
1/SOLVE_TWEAK));
1/_solverDelta));
applyLiftRatio(Math::pow(rg->getYasimLiftFactor(),
1/SOLVE_TWEAK));
1/_solverDelta));
}
else
//huh, no wing and no rotor? (_rotorgear is constructed,
//if a rotor is defined
{
applyDragFactor(Math::pow(15.7/1000, 1/SOLVE_TWEAK));
applyLiftRatio(Math::pow(104, 1/SOLVE_TWEAK));
applyDragFactor(Math::pow(15.7/1000, 1/_solverDelta));
applyLiftRatio(Math::pow(104, 1/_solverDelta));
}
_cruiseConfig.state.setupState(0,0,0);
_model.setState(&_cruiseConfig.state);
@ -1126,4 +1125,20 @@ float Airplane::getMaxThrust()
return sum[0];
}
float Airplane::getTailIncidence() const
{
if (_tailIncidence != nullptr) {
return _tailIncidence->val;
}
else return 0;
}
float Airplane::getApproachElevator() const
{
if (_approachElevator != nullptr) {
return _approachElevator->val;
}
else return 0;
}
}; // namespace yasim

18
src/FDM/YASim/Airplane.hpp
View file

@ -92,7 +92,7 @@ public:
float getFuelDensity(int tank) const { return ((Tank*)_tanks.get(tank))->density; }
float getTankCapacity(int tank) const { return ((Tank*)_tanks.get(tank))->cap; }
void compile(); // generate point masses & such, then solve
void compile(bool verbose = false); // generate point masses & such, then solve
void initEngines();
void stabilizeThrust();
@ -101,8 +101,8 @@ public:
float getDragCoefficient() const { return _dragFactor; }
float getLiftRatio() const { return _liftRatio; }
float getCruiseAoA() const { return _cruiseConfig.aoa; }
float getTailIncidence() const { return _tailIncidence->val; }
float getApproachElevator() const { return _approachElevator->val; }
float getTailIncidence()const;
float getApproachElevator() const;
const char* getFailureMsg() const { return _failureMsg; }
// next two are used only in yasim CLI tool
@ -130,6 +130,9 @@ public:
float getMaxThrust();
float getThrust2WeightEmpty() { return getMaxThrust()/(_emptyWeight * KG2N); };
float getThrust2WeightMTOW() { return getMaxThrust()/(_mtow*KG2N); };
void setSolverTweak(float f) { _solverDelta = f; };
void setSolverThreshold(float threshold) { _solverThreshold = threshold; };
void setSolverMaxIterations(int i) { _solverMaxIterations = i; };
private:
struct Tank {
@ -191,8 +194,8 @@ private:
void solveGear();
float _getPitch(Config &cfg);
float _getLift(Config &cfg);
void solveAirplane();
void solveHelicopter();
void solveAirplane(bool verbose = false);
void solveHelicopter(bool verbose = false);
float compileWing(Wing* w);
void compileRotorgear();
float compileFuselage(Fuselage* f);
@ -215,6 +218,11 @@ private:
/// set property name controling tail trim (incidence)
void setHstabTrimControl(const char* propName);
float _solverDelta {0.3226};
// How close to the solution are we trying get?
// Trying too hard can result in oscillations (no convergence).
float _solverThreshold {1};
int _solverMaxIterations {4000};
Model _model;
ControlMap _controlMap;

1
src/FDM/YASim/yasim-common.hpp
View file

@ -8,7 +8,6 @@
common file for YASim wide constants and static helper functions
*/
namespace yasim {
static const int SOLVER_MAX_ITERATIONS = 4000;
static const float YASIM_PI = 3.14159265358979323846f;
static const float PI2 = YASIM_PI*2;
static const float RAD2DEG = 180/YASIM_PI;

16
src/FDM/YASim/yasim-test.cpp
View file

@ -262,11 +262,21 @@ int main(int argc, char** argv)
catch (const sg_exception &e) {
printf("XML parse error: %s (%s)\n", e.getFormattedMessage().c_str(), e.getOrigin());
}
// ... and run
a->compile();
if(a->getFailureMsg())
bool verbose {false};
if (argc > 2 && strcmp(argv[2], "-v") == 0) {
verbose=true;
}
if ((argc == 4) && (strcmp(argv[2], "--tweak") == 0)) {
float tweak = std::atof(argv[3]);
a->setSolverTweak(tweak);
a->setSolverMaxIterations(2000);
verbose=true;
}
a->compile(verbose);
if(a->getFailureMsg()) {
printf("SOLUTION FAILURE: %s\n", a->getFailureMsg());
}
if(!a->getFailureMsg() && argc > 2 ) {
bool test = (strcmp(argv[2], "-test") == 0);
if((strcmp(argv[2], "-g") == 0) || test)