Package com.irurueta.navigation.inertial.calibration.magnetometer

Class PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

java.lang.Object

com.irurueta.navigation.inertial.calibration.magnetometer.RobustKnownHardIronAndFrameMagnetometerCalibrator

com.irurueta.navigation.inertial.calibration.magnetometer.PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

All Implemented Interfaces:

KnownHardIronMagnetometerCalibrator, MagnetometerCalibrator, MagnetometerNonLinearCalibrator, OrderedStandardDeviationFrameBodyMagneticFluxDensityMagnetometerCalibrator, QualityScoredMagnetometerCalibrator

public class PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator
extends RobustKnownHardIronAndFrameMagnetometerCalibrator

Robustly estimates magnetometer soft-iron cross couplings and scaling factors using PROMedS algorithm.

To use this calibrator at least 4 measurements at different known frames must be provided. In other words, magnetometer samples must be obtained at 4 different positions or orientations. Notice that frame velocities are ignored by this calibrator.

Measured magnetic flux density is assumed to follow the model shown below:

     mBmeas = bm + (I + Mm) * mBtrue + w
 

Where: - mBmeas is the measured magnetic flux density. This is a 3x1 vector. - bm is magnetometer hard-iron bias. Ideally, on a perfect magnetometer, this should be a 3x1 zero vector. - I is the 3x3 identity matrix. - Mm is the 3x3 soft-iron matrix containing cross-couplings and scaling factors. Ideally, on a perfect magnetometer, this should be a 3x3 zero matrix. - mBtrue is ground-truth magnetic flux density. This is a 3x1 vector. - w is measurement noise. This is a 3x1 vector.

Field Summary

Fields

Modifier and Type	Field	Description
static final double	DEFAULT_STOP_THRESHOLD	Default value to be used for stop threshold.
static final double	MIN_STOP_THRESHOLD	Minimum allowed stop threshold value.
private double[]	qualityScores	Quality scores corresponding to each provided sample.
private double	stopThreshold	Threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough.

Fields inherited from class com.irurueta.navigation.inertial.calibration.magnetometer.RobustKnownHardIronAndFrameMagnetometerCalibrator

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
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator()	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(boolean commonAxisUsed)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(boolean commonAxisUsed, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, boolean commonAxisUsed)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, boolean commonAxisUsed, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyMagneticFluxDensity> measurements)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, boolean commonAxisUsed)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, boolean commonAxisUsed, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores, List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, boolean commonAxisUsed)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, boolean commonAxisUsed, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.
PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements, RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)	Constructor.

Method Summary

Modifier and Type	Method	Description
void	calibrate()	Estimates magnetometer calibration parameters containing soft-iron 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	getStopThreshold()	Returns threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough.
private void	internalSetQualityScores(double[] qualityScores)	Sets quality scores corresponding to each provided sample.
boolean	isQualityScoresRequired()	Indicates whether this calibrator requires quality scores for each measurement or not.
boolean	isReady()	Indicates whether solver is ready to find a solution.
void	setQualityScores(double[] qualityScores)	Sets quality scores corresponding to each provided sample.
void	setStopThreshold(double stopThreshold)	Sets threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough.

Methods inherited from class com.irurueta.navigation.inertial.calibration.magnetometer.RobustKnownHardIronAndFrameMagnetometerCalibrator

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, getConfidence, getEstimatedChiSq, getEstimatedCovariance, getEstimatedMm, getEstimatedMse, getEstimatedMxy, getEstimatedMxz, getEstimatedMyx, getEstimatedMyz, getEstimatedMzx, getEstimatedMzy, getEstimatedSx, getEstimatedSy, getEstimatedSz, getHardIron, getHardIron, getHardIronAsTriad, getHardIronAsTriad, getHardIronMatrix, getHardIronMatrix, getHardIronX, getHardIronXAsMagneticFluxDensity, getHardIronXAsMagneticFluxDensity, getHardIronY, getHardIronYAsMagneticFluxDensity, getHardIronYAsMagneticFluxDensity, getHardIronZ, getHardIronZAsMagneticFluxDensity, getHardIronZAsMagneticFluxDensity, getInitialMm, getInitialMm, getInitialMxy, getInitialMxz, getInitialMyx, getInitialMyz, getInitialMzx, getInitialMzy, getInitialSx, getInitialSy, getInitialSz, getInliersData, getListener, getMagneticModel, getMaxIterations, getMeasurements, getMeasurementType, getMinimumRequiredMeasurements, getPreliminarySubsetSize, getProgressDelta, isCommonAxisUsed, isCovarianceKept, isLinearCalibratorUsed, isOrderedMeasurementsRequired, isPreliminarySolutionRefined, isResultRefined, isRunning, setCommonAxisUsed, setConfidence, setCovarianceKept, setHardIron, setHardIron, setHardIron, setHardIronCoordinates, setHardIronCoordinates, setHardIronX, setHardIronX, setHardIronY, setHardIronY, setHardIronZ, setHardIronZ, setInitialCrossCouplingErrors, setInitialMm, setInitialMxy, setInitialMxz, setInitialMyx, setInitialMyz, setInitialMzx, setInitialMzy, setInitialScalingFactors, setInitialScalingFactorsAndCrossCouplingErrors, setInitialSx, setInitialSy, setInitialSz, setLinearCalibratorUsed, setListener, setMagneticModel, setMaxIterations, setMeasurements, setPreliminarySolutionRefined, setPreliminarySubsetSize, setProgressDelta, setResultRefined, setupWmmEstimator

Methods inherited from class java.lang.Object

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

Field Details

DEFAULT_STOP_THRESHOLD

public static final double DEFAULT_STOP_THRESHOLD

Default value to be used for stop threshold. Stop threshold can be used to avoid keeping the algorithm unnecessarily iterating in case that best estimated threshold using median of residuals is not small enough. Once a solution is found that generates a threshold below this value, the algorithm will stop. The stop threshold can be used to prevent the LMedS algorithm iterating too many times in cases where samples have a very similar accuracy. For instance, in cases where proportion of outliers is very small (close to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would iterate for a long time trying to find the best solution when indeed there is no need to do that if a reasonable threshold has already been reached. Because of this behaviour the stop threshold can be set to a value much lower than the one typically used in RANSAC, and yet the algorithm could still produce even smaller thresholds in estimated results.

See Also:

• Constant Field Values

MIN_STOP_THRESHOLD

public static final double MIN_STOP_THRESHOLD

Minimum allowed stop threshold value.

See Also:

• Constant Field Values

stopThreshold

private double stopThreshold

Threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough. Once a solution is found that generates a threshold below this value, the algorithm will stop. The stop threshold can be used to prevent the LMedS algorithm iterating too many times in cases where samples have a very similar accuracy. For instance, in cases where proportion of outliers is very small (close to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would iterate for a long time trying to find the best solution when indeed there is no need to do that if a reasonable threshold has already been reached. Because of this behaviour the stop threshold can be set to a value much lower than the one typically used in RANSAC, and yet the algorithm could still produce even smaller thresholds in estimated results.

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

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator()

Constructor.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)

Constructor.

Parameters:

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

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements)

Constructor.

Parameters:

measurements - list of body magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)

Constructor.

Parameters:

measurements - list of body magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

listener - listener to handle events raised by this calibrator.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(boolean commonAxisUsed)

Constructor.

Parameters:

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

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(boolean commonAxisUsed,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)

Constructor.

Parameters:

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

listener - listener to handle events raised by this calibrator.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements,
 boolean commonAxisUsed)

Constructor.

Parameters:

measurements - list of body magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

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

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(List<StandardDeviationFrameBodyMagneticFluxDensity> measurements,
 boolean commonAxisUsed,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener listener)

Constructor.

Parameters:

measurements - list of body magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

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

listener - listener to handle events raised by this calibrator.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(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 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener 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 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyMagneticFluxDensity> 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 magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyMagneticFluxDensity> measurements,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener 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 magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(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 the accelerometer, gyroscope and magnetometer.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 boolean commonAxisUsed,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener 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 the accelerometer, gyroscope and magnetometer.

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyMagneticFluxDensity> 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 magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

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

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator

public PROMedSRobustKnownHardIronAndFrameMagnetometerCalibrator(double[] qualityScores,
 List<StandardDeviationFrameBodyMagneticFluxDensity> measurements,
 boolean commonAxisUsed,
 RobustKnownHardIronAndFrameMagnetometerCalibratorListener 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 magnetic flux density measurements with standard deviations taken at different frames (positions and orientations).

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

listener - listener to handle events raised by this calibrator.

Throws:

IllegalArgumentException - if provided quality scores length is smaller than 3 samples.

Method Details

getStopThreshold

public double getStopThreshold()

Returns threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough. Once a solution is found that generates a threshold below this value, the algorithm will stop. The stop threshold can be used to prevent the LMedS algorithm to iterate too many times in cases where samples have a very similar accuracy. For instance, in cases where proportion of outliers is very small (close to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would iterate for a long time trying to find the best solution when indeed there is no need to do that if a reasonable threshold has already been reached. Because of this behaviour the stop threshold can be set to a value much lower than the one typically used in RANSAC, and yet the algorithm could still produce even smaller thresholds in estimated results.

Returns:

stop threshold to stop the algorithm prematurely when a certain accuracy has been reached.

setStopThreshold

public void setStopThreshold(double stopThreshold)
                      throws com.irurueta.navigation.LockedException

Sets threshold to be used to keep the algorithm iterating in case that best estimated threshold using median of residuals is not small enough. Once a solution is found that generates a threshold below this value, the algorithm will stop. The stop threshold can be used to prevent the LMedS algorithm to iterate too many times in cases where samples have a very similar accuracy. For instance, in cases where proportion of outliers is very small (close to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would iterate for a long time trying to find the best solution when indeed there is no need to do that if a reasonable threshold has already been reached. Because of this behaviour the stop threshold can be set to a value much lower than the one typically used in RANSAC, and yet the algorithm could still produce even smaller thresholds in estimated results.

Parameters:

stopThreshold - stop threshold to stop the algorithm prematurely when a certain accuracy has been reached.

Throws:

IllegalArgumentException - if provided value is zero or negative.

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 QualityScoredMagnetometerCalibrator

Overrides:

getQualityScores in class RobustKnownHardIronAndFrameMagnetometerCalibrator

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 QualityScoredMagnetometerCalibrator

Overrides:

setQualityScores in class RobustKnownHardIronAndFrameMagnetometerCalibrator

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 solver is ready to find a solution.

Specified by:

isReady in interface MagnetometerCalibrator

Overrides:

isReady in class RobustKnownHardIronAndFrameMagnetometerCalibrator

Returns:

true if solver is ready, false otherwise.

calibrate

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

Estimates magnetometer calibration parameters containing soft-iron 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 RobustKnownHardIronAndFrameMagnetometerCalibrator

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 3 samples.