org.orekit.ssa.collision.shorttermencounter.probability.twod

Class Alfriend1999Max

java.lang.Object

org.orekit.ssa.collision.shorttermencounter.probability.twod.AbstractShortTermEncounter2DPOCMethod

org.orekit.ssa.collision.shorttermencounter.probability.twod.AbstractAlfriend1999

org.orekit.ssa.collision.shorttermencounter.probability.twod.Alfriend1999Max

All Implemented Interfaces:

ShortTermEncounter2DPOCMethod

public class Alfriend1999Max
extends AbstractAlfriend1999

Compute the probability of collision assuming the worst case described in : "Kyle Alfriend, Maruthi Akella, Joseph Frisbee, James Foster, Deok-Jin Lee, and Matthew Wilkins. Probability of ProbabilityOfCollision Error Analysis. Space Debris, 1(1):21–35, 1999.".

It assumes:

• Short encounter leading to a linear relative motion.
• Spherical collision object.
• Uncorrelated positional covariance.
• Gaussian distribution of the position uncertainties.
• Deterministic velocity i.e. no velocity uncertainties.
• Both objects are in circular orbits (eq 14).
• Probability density function is constant over the collision circle (eq 18).
• Covariance multiplied by a coefficient KSquared = MahalanobisDistanceSquared / 2 (eq 19-20).

By assuming a constant probability density function over the collision circle this method will, most of the time, give much higher probability of collision than other regular methods. That is why it is qualified as a maximum probability of collision computing method.

Since:

12.0

Author:

Vincent Cucchietti

See Also:

Mahalanobis distance.

Field Summary

Fields inherited from class org.orekit.ssa.collision.shorttermencounter.probability.twod.AbstractShortTermEncounter2DPOCMethod

DEFAULT_TCA_DIFFERENCE_TOLERANCE

Fields inherited from interface org.orekit.ssa.collision.shorttermencounter.probability.twod.ShortTermEncounter2DPOCMethod

DEFAULT_ZERO_THRESHOLD

Constructor Summary

Constructors

Constructor and Description
Alfriend1999Max() Empty constructor.

Method Summary

Modifier and Type	Method and Description
double	computeValue(double radius, double squaredMahalanobisDistance, double covarianceMatrixDeterminant) Compute the value of the probability of collision.
<T extends org.hipparchus.CalculusFieldElement<T>> T	computeValue(T radius, T squaredMahalanobisDistance, T covarianceMatrixDeterminant) Compute the value of the probability of collision.
ShortTermEncounter2DPOCMethodType	getType() Get type of the method.
boolean	isAMaximumProbabilityOfCollisionMethod() Get flag that defines if the method is a maximum probability of collision computing method.

Methods inherited from class org.orekit.ssa.collision.shorttermencounter.probability.twod.AbstractAlfriend1999

compute, compute

Methods inherited from class org.orekit.ssa.collision.shorttermencounter.probability.twod.AbstractShortTermEncounter2DPOCMethod

compute, compute, compute, compute, compute, compute, getName, getObjectOrbitFromCdm, getObjectStateCovarianceFromCdm

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.orekit.ssa.collision.shorttermencounter.probability.twod.ShortTermEncounter2DPOCMethod

compute, compute, compute, compute, compute, compute, compute, compute, compute

Constructor Detail

Alfriend1999Max

public Alfriend1999Max()

Empty constructor.

Method Detail

computeValue

public double computeValue(double radius,
                           double squaredMahalanobisDistance,
                           double covarianceMatrixDeterminant)

Compute the value of the probability of collision.

Parameters:

radius - sum of primary and secondary collision object equivalent sphere radii (m)

squaredMahalanobisDistance - squared Mahalanobis distance

covarianceMatrixDeterminant - covariance matrix determinant

Returns:

value of the probability of collision

computeValue

public <T extends org.hipparchus.CalculusFieldElement<T>> T computeValue(T radius,
                                                                         T squaredMahalanobisDistance,
                                                                         T covarianceMatrixDeterminant)

Compute the value of the probability of collision.

Type Parameters:

T - type of the field elements

Parameters:

radius - sum of primary and secondary collision object equivalent sphere radii (m)

squaredMahalanobisDistance - squared Mahalanobis distance

covarianceMatrixDeterminant - covariance matrix determinant

Returns:

value of the probability of collision

isAMaximumProbabilityOfCollisionMethod

public boolean isAMaximumProbabilityOfCollisionMethod()

Get flag that defines if the method is a maximum probability of collision computing method.

Specified by:

isAMaximumProbabilityOfCollisionMethod in interface ShortTermEncounter2DPOCMethod

Overrides:

isAMaximumProbabilityOfCollisionMethod in class AbstractShortTermEncounter2DPOCMethod

Returns:

flag that defines if the method is a maximum probability of collision computing method

getType

public ShortTermEncounter2DPOCMethodType getType()

Get type of the method.

Returns:

type of the method