Re: [Orekit Users] My EventDetector class can't correct detecting event?

[beowulf zhang <beowulf.zhang@gmail.com>]

I finded that the integrator called the class CombinedEventsManager
and EventState of the common-math, not those in the orekit5. why?

2011/5/31, beowulf zhang <beowulf.zhang@gmail.com>:
> I find recursive in debug, stack is:
>
> ClassicalRungeKuttaIntegrator(RungeKuttaIntegrator).integrate(FirstOrderDifferentialEquations,
> double, double[], double, double[]) line: 172
> NumericalPropagator.propagate(AbsoluteDate) line: 419	
> NumericalPropagator.getPVCoordinates(AbsoluteDate, Frame) line: 462	
> LocalOrbitalFrame.updateFrame(AbsoluteDate) line: 81	
> EME2000Frame(Frame).getTransformTo(Frame, AbsoluteDate) line: 201	
> EquinoctialOrbit(Orbit).getPVCoordinates(Frame) line: 240	
> SpacecraftState.getPVCoordinates(Frame) line: 361	
> CWAxisYDetector.g(SpacecraftState) line: 37	
> AdaptedEventDetector.g(double, double[]) line: 74	
> EventState.reinitializeBegin(double, double[]) line: 152	
> CombinedEventsManager.evaluateStep(StepInterpolator) line: 142	
> ClassicalRungeKuttaIntegrator(RungeKuttaIntegrator).integrate(FirstOrderDifferentialEquations,
> double, double[], double, double[]) line: 172
> NumericalPropagator.propagate(AbsoluteDate) line: 419	
> SlaveMode.main(String[]) line: 138	
>
> Maybe this is a debug!
>
> 2011/5/31, beowulf zhang <beowulf.zhang@gmail.com>:
>> locOrbFrm object is referenced to another object.
>>
>> My main function code is:
>>
>>             // configure Orekit
>>             Autoconfiguration.configureOrekit();
>>
>>             // Initial orbit parameters
>>             double a = 7396159; // semi major axis in meters
>>             double e = 0.001; // eccentricity
>>             double i = Math.toRadians(7); // inclination
>>             double omega = Math.toRadians(180); // perigee argument
>>             double raan = Math.toRadians(261); // right ascension of
>> ascending node
>>             double lM = 0; // mean anomaly
>>
>>             // Inertial frame
>>             Frame inertialFrame = FramesFactory.getEME2000();
>>
>>             // Initial date in UTC time scale
>>             TimeScale utc = TimeScalesFactory.getUTC();
>>             AbsoluteDate initialDate = new AbsoluteDate(2004, 01, 01,
>> 23, 30, 00.000, utc);
>>
>>             // gravitation coefficient
>>             double mu =  3.986004415e+14;
>>
>>
>> //////////////////////////////////////////////////////////////////////////////////
>>             // Orbit construction as Keplerian
>>             Orbit initialOrbit = new KeplerianOrbit(a, e, i, omega, raan,
>> lM,
>>
>> KeplerianOrbit.MEAN_ANOMALY,
>>                                                     inertialFrame,
>> initialDate, mu);
>>
>>             // Simple extrapolation with Keplerian motion
>>             //KeplerianPropagator kepler = new
>> KeplerianPropagator(initialOrbit);
>>             double stepSize = 9;  // the step is ten seconds
>>             FirstOrderIntegrator integrator = new
>> ClassicalRungeKuttaIntegrator(stepSize);
>>             NumericalPropagator prop = new
>> NumericalPropagator(integrator);
>>             SpacecraftState initialState = new
>> SpacecraftState(initialOrbit);
>>             prop.setInitialState(initialState);
>>
>>             // Set the propagator to slave mode (could be omitted as
>> it is the default mode)
>>             prop.setSlaveMode();
>>
>>             // 生成目标当地轨道系
>>             LocalOrbitalFrame lof = new
>> LocalOrbitalFrame(inertialFrame, LOFType.QSW, prop, "LOF");
>>
>>
>> //////////////////////////////////////////////////////////////////////////////////
>>             // 根据相对状态构造追踪星
>>             PVCoordinates relSt = new PVCoordinates(new
>> Vector3D(0.0,0.0,0.0),
>>             										new Vector3D(0.0,1.0,0.0));
>>             PVCoordinates initPV = lof.getTransformTo(inertialFrame,
>>             										  initialDate).transformPVCoordinates(relSt);
>>
>>             // Simple extrapolation with Keplerian motion
>>             //KeplerianPropagator kepler = new
>> KeplerianPropagator(initialOrbit);
>>             FirstOrderIntegrator integratorS = new
>> ClassicalRungeKuttaIntegrator(stepSize);
>>             NumericalPropagator propS = new
>> NumericalPropagator(integratorS);
>>             SpacecraftState initialStateS = new SpacecraftState(new
>> CartesianOrbit(initPV,
>>             		inertialFrame, initialDate, mu));
>>             propS.setInitialState(initialStateS);
>>
>>             // Set the propagator to slave mode (could be omitted as
>> it is the default mode)
>>             propS.setSlaveMode();
>>             propS.addEventDetector(new CWAxisYDetector(initialOrbit,
>> lof, initialDate));
>>
>>
>> //////////////////////////////////////////////////////////////////////////////////
>>             // Overall duration in seconds for extrapolation
>>             double duration = initialOrbit.getKeplerianPeriod() * 2.0;
>>
>>             PrintWriter relFile = null;
>>             try {
>> 				relFile = new PrintWriter("relst.txt");
>> 			} catch (FileNotFoundException e1) {
>> 				e1.printStackTrace();
>> 			}
>>
>>             // Stop date
>>             final AbsoluteDate finalDate =  new
>> AbsoluteDate(initialDate, duration, utc);
>>
>>             // Extrapolation loop
>>             boolean first = true;
>>             AbsoluteDate extrapDate = initialDate;
>>             while (extrapDate.compareTo(finalDate) <= 0)  {
>>
>>                 SpacecraftState targ = prop.propagate(extrapDate);
>>                 SpacecraftState inter = propS.propagate(extrapDate);
>>                 PVCoordinates relst = inter.getPVCoordinates(lof);
>>                 double tm = extrapDate.durationFrom(initialDate);
>>                 relFile.printf("%f %f %f %f\n",
>>                 		tm, relst.getPosition().getX(),
>> relst.getPosition().getY(), relst.getPosition().getZ());
>>
>>                 extrapDate = new AbsoluteDate(extrapDate, stepSize, utc);
>>             }
>>
>>             relFile.close();
>>             System.out.println("The End");
>>
>>
>> 2011/5/31, MAISONOBE Luc <luc.maisonobe@c-s.fr>:
>>> beowulf zhang <beowulf.zhang@gmail.com> a écrit :
>>>
>>>> I write a class CWAxisYDetector derived from AbstractDetector, the code
>>>> is:
>>>>
>>>> public class CWAxisYDetector extends AbstractDetector {
>>>>
>>>> 	private LocalOrbitalFrame locOrbFrm;
>>>>
>>>> 	private AbsoluteDate initDate;
>>>>
>>>> 	protected CWAxisYDetector(Orbit targOrb, LocalOrbitalFrame lof,
>>>> AbsoluteDate iDate) {
>>>> 		super(targOrb.getKeplerianPeriod() / 3, 1.0e-13 *
>>>> targOrb.getKeplerianPeriod());
>>>> 		this.locOrbFrm = lof;
>>>> 		this.initDate = iDate;
>>>> 	}
>>>>
>>>> 	public int eventOccurred(SpacecraftState s, boolean increasing)
>>>> 			throws OrekitException {
>>>> 		System.out.println(s.getDate().durationFrom(initDate));
>>>> 		return CONTINUE;
>>>> 	}
>>>>
>>>> 	public double g(SpacecraftState s) throws OrekitException {
>>>> 		return s.getPVCoordinates(locOrbFrm).getPosition().getX();
>>>> 	}
>>>
>>> If the local orbital frame here is linked to the same spacecraft whose
>>> orbit is propagated, then
>>> s.getPVCoordinates(locOrbFrm).getPosition().getX() should always be 0
>>> (as well as Y and Z since the spacecraft defines the origin of this
>>> frame).
>>> So the function is essentially an observation of numerical errors in
>>> interpolation polynomials, it is not a function that clearly crosses
>>> the zero axis at one precise time.
>>>
>>> Are you sure about the frame ? Shouldn't it be related to another
>>> spacecraft (for relative motion observation for example) ?
>>>
>>> Luc
>>>
>>>>
>>>> }
>>>>
>>>> but this class can't correct detecting event, and in some integrate
>>>> step getinig error information:
>>>>
>>>> Exception in thread "main"
>>>> org.apache.commons.math.MathRuntimeException$4: function values at
>>>> endpoints do not have different signs.  Endpoints: [0.539, 0.539],
>>>> Values: [0, 0]
>>>> 	at
>>>> org.apache.commons.math.MathRuntimeException.createIllegalArgumentException(MathRuntimeException.java:305)
>>>> 	at
>>>> org.apache.commons.math.analysis.solvers.BrentSolver.solve(BrentSolver.java:219)
>>>> 	at
>>>> org.apache.commons.math.ode.events.EventState.evaluateStep(EventState.java:229)
>>>> 	at
>>>> org.apache.commons.math.ode.events.CombinedEventsManager.evaluateStep(CombinedEventsManager.java:152)
>>>> 	at
>>>> org.apache.commons.math.ode.nonstiff.RungeKuttaIntegrator.integrate(RungeKuttaIntegrator.java:172)
>>>> 	at
>>>> org.orekit.propagation.numerical.NumericalPropagator.propagate(NumericalPropagator.java:419)
>>>> 	at fr.cs.examples.propagation.SlaveMode.main(SlaveMode.java:136)
>>>>
>>>> why?
>>>>
>>>>
>>>
>>>
>>>
>>> ----------------------------------------------------------------
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>>>
>>>
>>>
>>
>