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tunernoise

Noise structure of fusion filter

Since R2020b

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Syntax

noiseStruct = tunernoise(filterName)
noiseStruct = tunernoise(filter)

Description

noiseStruct = tunernoise(filterName) returns the measurement noise structure for the filter with name specified by the filterName input.

example

noiseStruct = tunernoise(filter) returns the measurement noise structure for the filter object.

example

Examples

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Open Live Script

Obtain the measurement noise structure of the insfilterAsync object.

noiseStruct = tunernoise('insfilterAsync')
noiseStruct = struct with fields:
    AccelerometerNoise: 1
        GyroscopeNoise: 1
     MagnetometerNoise: 1
      GPSPositionNoise: 1
      GPSVelocityNoise: 1
Open Live Script

Load the recorded sensor data and ground truth data.

load('insfilterAsyncTuneData.mat');

Create timetables for the sensor data and the truth data.

sensorData = timetable(Accelerometer, Gyroscope, ...
    Magnetometer, GPSPosition, GPSVelocity, 'SampleRate', 100);
groundTruth = timetable(Orientation, Position, ...
    'SampleRate', 100);

Create an insfilterAsync filter object that has a few noise properties.

filter = insfilterAsync('State', initialState, ...
    'StateCovariance', initialStateCovariance, ...
    'AccelerometerBiasNoise', 1e-7, ...
    'GyroscopeBiasNoise', 1e-7, ...
    'MagnetometerBiasNoise', 1e-7, ...
    'GeomagneticVectorNoise', 1e-7);

Create a tuner configuration object for the filter. Set the maximum iterations to two. Also, set the tunable parameters as the unspecified properties.

config = tunerconfig('insfilterAsync','MaxIterations',8);
config.TunableParameters = setdiff(config.TunableParameters, ...
    {'GeomagneticVectorNoise', 'AccelerometerBiasNoise', ...
    'GyroscopeBiasNoise', 'MagnetometerBiasNoise'});
config.TunableParameters
ans = 1×10 string
    "AccelerationNoise"    "AccelerometerNoise"    "AngularVelocityNoise"    "GPSPositionNoise"    "GPSVelocityNoise"    "GyroscopeNoise"    "MagnetometerNoise"    "PositionNoise"    "QuaternionNoise"    "VelocityNoise"

Use the tuner noise function to obtain a set of initial sensor noises used in the filter.

measNoise = tunernoise('insfilterAsync')
measNoise = struct with fields:
    AccelerometerNoise: 1
        GyroscopeNoise: 1
     MagnetometerNoise: 1
      GPSPositionNoise: 1
      GPSVelocityNoise: 1

Tune the filter and obtain the tuned parameters.

tunedParams = tune(filter,measNoise,sensorData,groundTruth,config);
    Iteration    Parameter               Metric
    _________    _________               ______
    1            AccelerationNoise       2.1345
    1            AccelerometerNoise      2.1264
    1            AngularVelocityNoise    1.9659
    1            GPSPositionNoise        1.9341
    1            GPSVelocityNoise        1.8420
    1            GyroscopeNoise          1.7589
    1            MagnetometerNoise       1.7362
    1            PositionNoise           1.7362
    1            QuaternionNoise         1.7218
    1            VelocityNoise           1.7218
    2            AccelerationNoise       1.7190
    2            AccelerometerNoise      1.7170
    2            AngularVelocityNoise    1.6045
    2            GPSPositionNoise        1.5948
    2            GPSVelocityNoise        1.5323
    2            GyroscopeNoise          1.4803
    2            MagnetometerNoise       1.4703
    2            PositionNoise           1.4703
    2            QuaternionNoise         1.4632
    2            VelocityNoise           1.4632
    3            AccelerationNoise       1.4596
    3            AccelerometerNoise      1.4548
    3            AngularVelocityNoise    1.3923
    3            GPSPositionNoise        1.3810
    3            GPSVelocityNoise        1.3322
    3            GyroscopeNoise          1.2998
    3            MagnetometerNoise       1.2976
    3            PositionNoise           1.2976
    3            QuaternionNoise         1.2943
    3            VelocityNoise           1.2943
    4            AccelerationNoise       1.2906
    4            AccelerometerNoise      1.2836
    4            AngularVelocityNoise    1.2491
    4            GPSPositionNoise        1.2258
    4            GPSVelocityNoise        1.1880
    4            GyroscopeNoise          1.1701
    4            MagnetometerNoise       1.1698
    4            PositionNoise           1.1698
    4            QuaternionNoise         1.1688
    4            VelocityNoise           1.1688
    5            AccelerationNoise       1.1650
    5            AccelerometerNoise      1.1569
    5            AngularVelocityNoise    1.1454
    5            GPSPositionNoise        1.1100
    5            GPSVelocityNoise        1.0778
    5            GyroscopeNoise          1.0709
    5            MagnetometerNoise       1.0675
    5            PositionNoise           1.0675
    5            QuaternionNoise         1.0669
    5            VelocityNoise           1.0669
    6            AccelerationNoise       1.0634
    6            AccelerometerNoise      1.0549
    6            AngularVelocityNoise    1.0549
    6            GPSPositionNoise        1.0180
    6            GPSVelocityNoise        0.9866
    6            GyroscopeNoise          0.9810
    6            MagnetometerNoise       0.9775
    6            PositionNoise           0.9775
    6            QuaternionNoise         0.9768
    6            VelocityNoise           0.9768
    7            AccelerationNoise       0.9735
    7            AccelerometerNoise      0.9652
    7            AngularVelocityNoise    0.9652
    7            GPSPositionNoise        0.9283
    7            GPSVelocityNoise        0.8997
    7            GyroscopeNoise          0.8947
    7            MagnetometerNoise       0.8920
    7            PositionNoise           0.8920
    7            QuaternionNoise         0.8912
    7            VelocityNoise           0.8912
    8            AccelerationNoise       0.8885
    8            AccelerometerNoise      0.8811
    8            AngularVelocityNoise    0.8807
    8            GPSPositionNoise        0.8479
    8            GPSVelocityNoise        0.8238
    8            GyroscopeNoise          0.8165
    8            MagnetometerNoise       0.8165
    8            PositionNoise           0.8165
    8            QuaternionNoise         0.8159
    8            VelocityNoise           0.8159

Fuse the sensor data using the tuned filter.

dt = seconds(diff(groundTruth.Time));
N = size(sensorData,1);
qEst = quaternion.zeros(N,1);
posEst = zeros(N,3);
% Iterate the filter for prediction and correction using sensor data.
for ii=1:N
    if ii ~= 1
        predict(filter, dt(ii-1));
    end
    if all(~isnan(Accelerometer(ii,:)))
        fuseaccel(filter,Accelerometer(ii,:), ...
            tunedParams.AccelerometerNoise);
    end
    if all(~isnan(Gyroscope(ii,:)))
        fusegyro(filter, Gyroscope(ii,:), ...
            tunedParams.GyroscopeNoise);
    end
    if all(~isnan(Magnetometer(ii,1)))
        fusemag(filter, Magnetometer(ii,:), ...
            tunedParams.MagnetometerNoise);
    end
    if all(~isnan(GPSPosition(ii,1)))
        fusegps(filter, GPSPosition(ii,:), ...
            tunedParams.GPSPositionNoise, GPSVelocity(ii,:), ...
            tunedParams.GPSVelocityNoise);
    end
    [posEst(ii,:), qEst(ii,:)] = pose(filter);
end

Compute the RMS errors. 

orientationError = rad2deg(dist(qEst, Orientation));
rmsorientationError = sqrt(mean(orientationError.^2))
rmsorientationError = 2.7801

positionError = sqrt(sum((posEst - Position).^2, 2));
rmspositionError = sqrt(mean( positionError.^2))
rmspositionError = 0.5966

Visualize the results.

figure();
t = (0:N-1)./ groundTruth.Properties.SampleRate;
subplot(2,1,1)
plot(t, positionError, 'b');
title("Tuned insfilterAsync" + newline + "Euclidean Distance Position Error")
xlabel('Time (s)');
ylabel('Position Error (meters)')
subplot(2,1,2)
plot(t, orientationError, 'b');
title("Orientation Error")
xlabel('Time (s)');
ylabel('Orientation Error (degrees)');

Input Arguments

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Name of fusion filter, specified as specified as one of these:

  • 'ahrs10filter'

  • 'insfilterAsync'

  • 'insfilterMARG'

  • 'insfitlerErrorState'

  • 'insfilterNonholonomic'

Fusion filter, specified as one of these fusion filter objects:

.

Output Arguments

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Structure of measurement noise, returned as a structure. The exact fields of structure depend on the filter object.

For example, the structure contains these fields for the insfilterAsync object.

FieldDescriptionDefault
AccelerometerNoiseVariance of accelerometer noise, specified as a scalar in (m/s2)21
GyroscopeNoiseVariance of gyroscope noise, specified as a scalar in (rad/s)21
MagnetometerNoiseVariance of magnetometer noise, specified as a scalar in (μT)2.1
GPSPositionNoiseVariance of GPS position noise, specified as a scalar in m21
GPSVelocityNoiseStandard deviation of GPS velocity noise, specified as a scalar in (m/s)21

To use this structure with a tune function, change the values of the noise to proper values as initial guesses for tuning the noise. When the function tunes the measurement noise, it tunes all the elements in each field together. For example, if the AccelerometerNoise is specified as diag([1 0.1 1]), then the tune function varies AccelerometerNoise as the product of a scalar and the original diag([1 0.1 1]).

Version History

Introduced in R2020b

See Also