initcvckf

Create constant velocity tracking cubature Kalman filter from detection report

Syntax

filter = initcvckf(detection)

Description

filter = initcvckf(detection) creates and initializes a constant velocity cubature Kalman filter from information contained in a detection report.

The function initializes a constant velocity state with the same convention as constvel and cvmeas, [x v_x y v_y z v_z].

Examples

Create Constant Velocity Tracking CKF Object from Rectangular Measurements

Create a constant velocity tracking cubature Kalman filter object, trackingCKF, from an initial detection report. The detection report is made from an initial 3-D position measurement of the Kalman filter state in rectangular coordinates. You can obtain the 3-D position measurement using the constant velocity measurement function, cvmeas.

This example uses the coordinates, x = 1, y = 3, z = 0 and a 3-D position measurement noise of [1 0.2 0; 0.2 2 0; 0 0 1].

detection = objectDetection(0, [1;3;0], 'MeasurementNoise', [1 0.2 0; 0.2 2 0; 0 0 1]);

Use initcvckf to create a trackingCKF filter initialized at the provided position and using the measurement noise defined above.

ckf = initcvckf(detection)

ckf = 
  trackingCKF with properties:

                          State: [6x1 double]
                StateCovariance: [6x6 double]

             StateTransitionFcn: @constvel
                   ProcessNoise: [3x3 double]
        HasAdditiveProcessNoise: 0

                 MeasurementFcn: @cvmeas
         HasMeasurementWrapping: 1
               MeasurementNoise: [3x3 double]
    HasAdditiveMeasurementNoise: 1

                EnableSmoothing: 0

Check the values of the state and the measurement noise. Verify that the filter state, ckf.State, has the same position components as the detection measurement, detection.Measurement.

ckf.State

ans = 6×1

     1
     0
     3
     0
     0
     0

Verify that the filter measurement noise, ckf.MeasurementNoise, is the same as the detection.MeasurementNoise values.

ckf.MeasurementNoise

ans = 3×3

    1.0000    0.2000         0
    0.2000    2.0000         0
         0         0    1.0000

Create Constant Velocity Tracking CKF Object from Spherical Measurements

Create a constant velocity tracking cubature Kalman filter object, trackingCKF, from an initial detection report. The detection report is made from an initial 3-D position measurement of the Kalman filter state in spherical coordinates. You can obtain the 3D position measurement using the constant velocity measurement function, cvmeas.

This example uses the coordinates, az = 30, e1 = 5, r = 100, rr = 4 and a measurement noise of diag([2.5, 2.5, 0.5, 1].^2).

meas = [30;5;100;4];
measNoise = diag([2.5, 2.5, 0.5, 1].^2);

Use the MeasurementParameters property of the detection object to define the frame. When not defined, the fields of the MeasurementParameters struct use default values. In this example, sensor position, sensor velocity, orientation, elevation, and range rate flags are default.

measParams = struct('Frame','spherical');
detection = objectDetection(0,meas,'MeasurementNoise',measNoise,...
    'MeasurementParameters',measParams) 

detection = 
  objectDetection with properties:

                     Time: 0
              Measurement: [4x1 double]
         MeasurementNoise: [4x4 double]
              SensorIndex: 1
            ObjectClassID: 0
    ObjectClassParameters: []
    MeasurementParameters: [1x1 struct]
         ObjectAttributes: {}

Use initcvckf to create a trackingCKF filter initialized at the provided position and using the measurement noise defined above.

ckf = initcvckf(detection)

ckf = 
  trackingCKF with properties:

                          State: [6x1 double]
                StateCovariance: [6x6 double]

             StateTransitionFcn: @constvel
                   ProcessNoise: [3x3 double]
        HasAdditiveProcessNoise: 0

                 MeasurementFcn: @cvmeas
         HasMeasurementWrapping: 1
               MeasurementNoise: [4x4 double]
    HasAdditiveMeasurementNoise: 1

                EnableSmoothing: 0

Verify that the filter state produces the same measurement as above.

meas2 = cvmeas(ckf.State, measParams)

meas2 = 4×1

   30.0000
    5.0000
  100.0000
    4.0000

Input Arguments

detection — Detection report

objectDetection object

Detection report, specified as an objectDetection object.

Example: detection = objectDetection(0,[1;4.5;3],'MeasurementNoise', [1.0 0 0; 0 2.0 0; 0 0 1.5])

Output Arguments

filter — Constant velocity cubature Kalman filter for object tracking

trackingCKF object

Constant velocity cubature Kalman filter for object tracking, returned as a trackingCKF object.

Algorithms

• The function computes the process noise matrix assuming a unit acceleration standard deviation.

• You can use this function as the FilterInitializationFcn property of trackerTOMHT and trackerGNN System objects.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2018b