Package com.irurueta.navigation.inertial.calibration.accelerometer

Class PROSACRobustKnownFrameAccelerometerCalibrator

java.lang.Object

com.irurueta.navigation.inertial.calibration.accelerometer.RobustKnownFrameAccelerometerCalibrator

com.irurueta.navigation.inertial.calibration.accelerometer.PROSACRobustKnownFrameAccelerometerCalibrator

All Implemented Interfaces:

AccelerometerCalibrator, AccelerometerNonLinearCalibrator, OrderedStandardDeviationFrameBodyKinematicsAccelerometerCalibrator, QualityScoredAccelerometerCalibrator, UnknownBiasAccelerometerCalibrator, UnknownBiasNonLinearAccelerometerCalibrator, AccelerometerBiasUncertaintySource, AccelerometerCalibrationSource

public class PROSACRobustKnownFrameAccelerometerCalibrator
extends RobustKnownFrameAccelerometerCalibrator

Robustly estimates accelerometer biases, cross couplings and scaling factors using a PROSAC algorithm to discard outliers.

To use this calibrator at least 4 measurements at different known frames must be provided. In other words, accelerometer samples must be obtained at 4 different positions, orientations and velocities (although typically velocities are always zero).

Measured specific force is assumed to follow the model shown below:

     fmeas = ba + (I + Ma) * ftrue + w
 

Where: - fmeas is the measured specific force. This is a 3x1 vector. - ba is accelerometer bias. Ideally, on a perfect accelerometer, this should be a 3x1 zero vector. - I is the 3x3 identity matrix. - Ma is the 3x3 matrix containing cross-couplings and scaling factors. Ideally, on a perfect accelerometer, this should be a 3x3 zero matrix. - ftrue is ground-truth specific force. - w is measurement noise.

Nested Class Summary

Nested classes/interfaces inherited from class com.irurueta.navigation.inertial.calibration.accelerometer.RobustKnownFrameAccelerometerCalibrator

RobustKnownFrameAccelerometerCalibrator.PreliminaryResult

Field Summary

Fields

Modifier and Type	Field	Description
private boolean	computeAndKeepInliers	Indicates whether inliers must be computed and kept.
private boolean	computeAndKeepResiduals	Indicates whether residuals must be computed and kept.
static final boolean	DEFAULT_COMPUTE_AND_KEEP_INLIERS	Indicates that by default inliers will only be computed but not kept.
static final boolean	DEFAULT_COMPUTE_AND_KEEP_RESIDUALS	Indicates that by default residuals will only be computed but not kept.
static final double	DEFAULT_THRESHOLD	Constant defining default threshold to determine whether samples are inliers or not.
static final double	MIN_THRESHOLD	Minimum value that can be set as threshold.
private double[]	qualityScores	Quality scores corresponding to each provided sample.
private double	threshold	Threshold to determine whether samples are inliers or not when testing possible solutions.

Fields inherited from class com.irurueta.navigation.inertial.calibration.accelerometer.RobustKnownFrameAccelerometerCalibrator

confidence, DEFAULT_CONFIDENCE, DEFAULT_KEEP_COVARIANCE, DEFAULT_MAX_ITERATIONS, DEFAULT_PROGRESS_DELTA, DEFAULT_REFINE_PRELIMINARY_SOLUTIONS, DEFAULT_REFINE_RESULT, DEFAULT_ROBUST_METHOD, DEFAULT_USE_COMMON_Z_AXIS, DEFAULT_USE_LINEAR_CALIBRATOR, inliersData, listener, MAX_CONFIDENCE, MAX_PROGRESS_DELTA, maxIterations, measurements, MIN_CONFIDENCE, MIN_ITERATIONS, MIN_PROGRESS_DELTA, MINIMUM_MEASUREMENTS, preliminarySubsetSize, progressDelta, refineResult, running

Constructor Summary

Constructors

Constructor	Description
PROSACRobustKnownFrameAccelerometerCalibrator()	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(boolean commonAxisUsed)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(boolean commonAxisUsed, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, boolean commonAxisUsed)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, boolean commonAxisUsed, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyKinematics> measurements)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyKinematics> measurements, boolean commonAxisUsed)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyKinematics> measurements, boolean commonAxisUsed, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyKinematics> measurements, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements, boolean commonAxisUsed)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements, boolean commonAxisUsed, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.
PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements, RobustKnownFrameAccelerometerCalibratorListener listener)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	calibrate()	Estimates accelerometer calibration parameters containing bias, scale factors and cross-coupling errors.
com.irurueta.numerical.robust.RobustEstimatorMethod	getMethod()	Returns method being used for robust estimation.
double[]	getQualityScores()	Returns quality scores corresponding to each provided sample.
double	getThreshold()	Gets threshold to determine whether samples are inliers or not when testing possible solutions.
private void	internalSetQualityScores(double[] qualityScores)	Sets quality scores corresponding to each provided sample.
boolean	isComputeAndKeepInliersEnabled()	Indicates whether inliers must be computed and kept.
boolean	isComputeAndKeepResiduals()	Indicates whether residuals must be computed and kept.
boolean	isQualityScoresRequired()	Indicates whether this calibrator requires quality scores for each measurement or not.
boolean	isReady()	Indicates whether calibrator is ready to find a solution.
void	setComputeAndKeepInliersEnabled(boolean computeAndKeepInliers)	Specifies whether inliers must be computed and kept.
void	setComputeAndKeepResidualsEnabled(boolean computeAndKeepResiduals)	Specifies whether residuals must be computed and kept.
void	setQualityScores(double[] qualityScores)	Sets quality scores corresponding to each provided sample.
void	setThreshold(double threshold)	Sets threshold to determine whether samples are inliers or not when testing possible solutions.

Methods inherited from class com.irurueta.navigation.inertial.calibration.accelerometer.RobustKnownFrameAccelerometerCalibrator

attemptRefine, computeError, computePreliminarySolutions, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, create, getConfidence, getEstimatedBiasAsTriad, getEstimatedBiasAsTriad, getEstimatedBiases, getEstimatedBiases, getEstimatedBiasesAsMatrix, getEstimatedBiasesAsMatrix, getEstimatedBiasFx, getEstimatedBiasFxAsAcceleration, getEstimatedBiasFxAsAcceleration, getEstimatedBiasFxStandardDeviation, getEstimatedBiasFxStandardDeviationAsAcceleration, getEstimatedBiasFxStandardDeviationAsAcceleration, getEstimatedBiasFxVariance, getEstimatedBiasFy, getEstimatedBiasFyAsAcceleration, getEstimatedBiasFyAsAcceleration, getEstimatedBiasFyStandardDeviation, getEstimatedBiasFyStandardDeviationAsAcceleration, getEstimatedBiasFyStandardDeviationAsAcceleration, getEstimatedBiasFyVariance, getEstimatedBiasFz, getEstimatedBiasFzAsAcceleration, getEstimatedBiasFzAsAcceleration, getEstimatedBiasFzStandardDeviation, getEstimatedBiasFzStandardDeviationAsAcceleration, getEstimatedBiasFzStandardDeviationAsAcceleration, getEstimatedBiasFzVariance, getEstimatedBiasStandardDeviation, getEstimatedBiasStandardDeviation, getEstimatedBiasStandardDeviationAverage, getEstimatedBiasStandardDeviationAverageAsAcceleration, getEstimatedBiasStandardDeviationAverageAsAcceleration, getEstimatedBiasStandardDeviationNorm, getEstimatedBiasStandardDeviationNormAsAcceleration, getEstimatedBiasStandardDeviationNormAsAcceleration, getEstimatedChiSq, getEstimatedCovariance, getEstimatedMa, getEstimatedMse, getEstimatedMxy, getEstimatedMxz, getEstimatedMyx, getEstimatedMyz, getEstimatedMzx, getEstimatedMzy, getEstimatedSx, getEstimatedSy, getEstimatedSz, getInitialBias, getInitialBias, getInitialBiasAsMatrix, getInitialBiasAsMatrix, getInitialBiasAsTriad, getInitialBiasAsTriad, getInitialBiasX, getInitialBiasXAsAcceleration, getInitialBiasXAsAcceleration, getInitialBiasY, getInitialBiasYAsAcceleration, getInitialBiasYAsAcceleration, getInitialBiasZ, getInitialBiasZAsAcceleration, getInitialBiasZAsAcceleration, getInitialMa, getInitialMa, getInitialMxy, getInitialMxz, getInitialMyx, getInitialMyz, getInitialMzx, getInitialMzy, getInitialSx, getInitialSy, getInitialSz, getInliersData, getListener, getMaxIterations, getMeasurements, getMeasurementType, getMinimumRequiredMeasurements, getPreliminarySubsetSize, getProgressDelta, isCommonAxisUsed, isCovarianceKept, isLinearCalibratorUsed, isOrderedMeasurementsRequired, isPreliminarySolutionRefined, isResultRefined, isRunning, setCommonAxisUsed, setConfidence, setCovarianceKept, setInitialBias, setInitialBias, setInitialBias, setInitialBias, setInitialBias, setInitialBiasX, setInitialBiasX, setInitialBiasY, setInitialBiasY, setInitialBiasZ, setInitialBiasZ, setInitialCrossCouplingErrors, setInitialMa, setInitialMxy, setInitialMxz, setInitialMyx, setInitialMyz, setInitialMzx, setInitialMzy, setInitialScalingFactors, setInitialScalingFactorsAndCrossCouplingErrors, setInitialSx, setInitialSy, setInitialSz, setLinearCalibratorUsed, setListener, setMaxIterations, setMeasurements, setPreliminarySolutionRefined, setPreliminarySubsetSize, setProgressDelta, setResultRefined

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_THRESHOLD

public static final double DEFAULT_THRESHOLD

Constant defining default threshold to determine whether samples are inliers or not.

See Also:

• Constant Field Values

MIN_THRESHOLD

public static final double MIN_THRESHOLD

Minimum value that can be set as threshold. Threshold must be strictly greater than 0.0.

See Also:

• Constant Field Values

DEFAULT_COMPUTE_AND_KEEP_INLIERS

public static final boolean DEFAULT_COMPUTE_AND_KEEP_INLIERS

Indicates that by default inliers will only be computed but not kept.

See Also:

• Constant Field Values

DEFAULT_COMPUTE_AND_KEEP_RESIDUALS

public static final boolean DEFAULT_COMPUTE_AND_KEEP_RESIDUALS

Indicates that by default residuals will only be computed but not kept.

See Also:

• Constant Field Values

threshold

private double threshold

Threshold to determine whether samples are inliers or not when testing possible solutions. The threshold refers to the amount of error on distance between estimated position and distances provided for each sample.

computeAndKeepInliers

private boolean computeAndKeepInliers

Indicates whether inliers must be computed and kept.

computeAndKeepResiduals

private boolean computeAndKeepResiduals

Indicates whether residuals must be computed and kept.

qualityScores

private double[] qualityScores

Quality scores corresponding to each provided sample. The larger the score value the better the quality of the sample.

Constructor Details

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator()

Constructor.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

listener - listener to be notified of events such as when estimation starts, ends or its progress significantly changes.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements)

Constructor.

Parameters:

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

listener - listener to handle events raised by this calibrator.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(boolean commonAxisUsed)

Constructor.

Parameters:

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(boolean commonAxisUsed,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

listener - listener to handle events raised by this calibrator.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements,
 boolean commonAxisUsed)

Constructor.

Parameters:

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(List<StandardDeviationFrameBodyKinematics> measurements,
 boolean commonAxisUsed,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

listener - listener to handle events raised by this calibrator.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

listener - listener to be notified of events such as when estimation starts, ends or its progress significantly changes.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyKinematics> measurements)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyKinematics> measurements,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 boolean commonAxisUsed)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 boolean commonAxisUsed,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyKinematics> measurements,
 boolean commonAxisUsed)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

PROSACRobustKnownFrameAccelerometerCalibrator

public PROSACRobustKnownFrameAccelerometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyKinematics> measurements,
 boolean commonAxisUsed,
 RobustKnownFrameAccelerometerCalibratorListener listener)

Constructor.

Parameters:

qualityScores - quality scores corresponding to each provided measurement. The larger the score value the better the quality of the sample.

measurements - list of body kinematics measurements with standard deviations taken at different frames (positions, orientations and velocities).

commonAxisUsed - indicates whether z-axis is assumed to be common for accelerometer and gyroscope.

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.

Method Details

getThreshold

public double getThreshold()

Gets threshold to determine whether samples are inliers or not when testing possible solutions. The threshold refers to the amount of error on norm between measured specific forces and the ones generated with estimated calibration parameters provided for each sample.

Returns:

threshold to determine whether samples are inliers or not.

setThreshold

public void setThreshold(double threshold)
                  throws com.irurueta.navigation.LockedException

Sets threshold to determine whether samples are inliers or not when testing possible solutions. The threshold refers to the amount of error on norm between measured specific forces and the ones generated with estimated calibration parameters provided for each sample.

Parameters:

threshold - threshold to determine whether samples are inliers or not.

Throws:

IllegalArgumentException - if provided value is equal or less than zero.

com.irurueta.navigation.LockedException - if calibrator is currently running.

getQualityScores

public double[] getQualityScores()

Returns quality scores corresponding to each provided sample. The larger the score value the better the quality of the sample.

Specified by:

getQualityScores in interface QualityScoredAccelerometerCalibrator

Overrides:

getQualityScores in class RobustKnownFrameAccelerometerCalibrator

Returns:

quality scores corresponding to each sample.

setQualityScores

public void setQualityScores(double[] qualityScores)
                      throws com.irurueta.navigation.LockedException

Sets quality scores corresponding to each provided sample. The larger the score value the better the quality of the sample.

Specified by:

setQualityScores in interface QualityScoredAccelerometerCalibrator

Overrides:

setQualityScores in class RobustKnownFrameAccelerometerCalibrator

Parameters:

qualityScores - quality scores corresponding to each sample.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than minimum required samples.

com.irurueta.navigation.LockedException - if calibrator is currently running.

isReady

public boolean isReady()

Indicates whether calibrator is ready to find a solution.

Specified by:

isReady in interface AccelerometerCalibrator

Overrides:

isReady in class RobustKnownFrameAccelerometerCalibrator

Returns:

true if calibrator is ready, false otherwise.

isComputeAndKeepInliersEnabled

public boolean isComputeAndKeepInliersEnabled()

Indicates whether inliers must be computed and kept.

Returns:

true if inliers must be computed and kept, false if inliers only need to be computed but not kept.

setComputeAndKeepInliersEnabled

public void setComputeAndKeepInliersEnabled(boolean computeAndKeepInliers)
                                     throws com.irurueta.navigation.LockedException

Specifies whether inliers must be computed and kept.

Parameters:

computeAndKeepInliers - true if inliers must be computed and kept, false if inliers only need to be computed but not kept.

Throws:

com.irurueta.navigation.LockedException - if calibrator is currently running.

isComputeAndKeepResiduals

public boolean isComputeAndKeepResiduals()

Indicates whether residuals must be computed and kept.

Returns:

true if residuals must be computed and kept, false if residuals only need to be computed but not kept.

setComputeAndKeepResidualsEnabled

public void setComputeAndKeepResidualsEnabled(boolean computeAndKeepResiduals)
                                       throws com.irurueta.navigation.LockedException

Specifies whether residuals must be computed and kept.

Parameters:

computeAndKeepResiduals - true if residuals must be computed and kept, false if residuals only need to be computed but not kept.

Throws:

com.irurueta.navigation.LockedException - if calibrator is currently running.

calibrate

public void calibrate()
               throws com.irurueta.navigation.LockedException,
com.irurueta.navigation.NotReadyException,
CalibrationException

Estimates accelerometer calibration parameters containing bias, scale factors and cross-coupling errors.

Throws:

com.irurueta.navigation.LockedException - if calibrator is currently running.

com.irurueta.navigation.NotReadyException - if calibrator is not ready.

CalibrationException - if estimation fails for numerical reasons.

getMethod

public com.irurueta.numerical.robust.RobustEstimatorMethod getMethod()

Returns method being used for robust estimation.

Specified by:

getMethod in class RobustKnownFrameAccelerometerCalibrator

Returns:

method being used for robust estimation.

isQualityScoresRequired

public boolean isQualityScoresRequired()

Indicates whether this calibrator requires quality scores for each measurement or not.

Returns:

true if quality scores are required, false otherwise.

internalSetQualityScores

private void internalSetQualityScores(double[] qualityScores)

Sets quality scores corresponding to each provided sample. This method is used internally and does not check whether instance is locked or not.

Parameters:

qualityScores - quality scores to be set.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 4 samples.