ctmeasjac
Syntax
Description
returns the measurement Jacobian, measurementjac
= ctmeasjac(state
)measurementjac
, for a
constant turn-rate Kalman filter motion model in rectangular coordinates.
state
specifies the current state of the track.
also specifies the measurement coordinate system, measurementjac
= ctmeasjac(state
,frame
)frame
.
also specifies the sensor position, measurementjac
= ctmeasjac(state
,frame
,sensorpos
)sensorpos
.
also
specifies the sensor velocity, measurementjac
= ctmeasjac(state
,frame
,sensorpos
,sensorvel
)sensorvel
.
specifies the measurement parameters,
measurementjac
= ctmeasjac(state
,measurementParameters
)measurementParameters
.
Examples
Measurement Jacobian of Constant Turn-Rate Motion in Rectangular Frame
Define the state of an object in 2-D constant turn-rate motion. The state is the position and velocity in each dimension, and the turn rate. Construct the measurement Jacobian in rectangular coordinates.
state = [1;10;2;20;5]; jacobian = ctmeasjac(state)
jacobian = 3×5
1 0 0 0 0
0 0 1 0 0
0 0 0 0 0
Measurement Jacobian of Constant Turn-Rate Motion in Spherical Frame
Define the state of an object in 2-D constant turn-rate motion. The state is the position and velocity in each dimension, and the turn rate. Compute the measurement Jacobian with respect to spherical coordinates.
state = [1;10;2;20;5];
measurementjac = ctmeasjac(state,'spherical')
measurementjac = 4×5
-22.9183 0 11.4592 0 0
0 0 0 0 0
0.4472 0 0.8944 0 0
0.0000 0.4472 0.0000 0.8944 0
Measurement Jacobian of Constant Turn-Rate Object in Translated Spherical Frame
Define the state of an object in 2-D constant turn-rate motion. The state is the position and velocity in each dimension, and the turn rate. Compute the measurement Jacobian with respect to spherical coordinates centered at [5;-20;0]
.
state = [1;10;2;20;5];
sensorpos = [5;-20;0];
measurementjac = ctmeasjac(state,'spherical',sensorpos)
measurementjac = 4×5
-2.5210 0 -0.4584 0 0
0 0 0 0 0
-0.1789 0 0.9839 0 0
0.5903 -0.1789 0.1073 0.9839 0
Measurement Jacobian of Constant Turn-Rate Object Using Measurement Parameters
Define the state of an object in 2-D constant turn-rate motion. The state is the position and velocity in each dimension, and the turn rate. Compute the measurement Jacobian with respect to spherical coordinates centered at [25;-40;0]
.
state2d = [1;10;2;20;5];
sensorpos = [25,-40,0].';
frame = 'spherical';
sensorvel = [0;5;0];
laxes = eye(3);
measurementjac = ctmeasjac(state2d,frame,sensorpos,sensorvel,laxes)
measurementjac = 4×5
-1.0284 0 -0.5876 0 0
0 0 0 0 0
-0.4961 0 0.8682 0 0
0.2894 -0.4961 0.1654 0.8682 0
Put the measurement parameters in a structure and use the alternative syntax.
measparm = struct('Frame',frame,'OriginPosition',sensorpos,'OriginVelocity',sensorvel, ... 'Orientation',laxes); measurementjac = ctmeasjac(state2d,measparm)
measurementjac = 4×5
-1.0284 0 -0.5876 0 0
0 0 0 0 0
-0.4961 0 0.8682 0 0
0.2894 -0.4961 0.1654 0.8682 0
Input Arguments
state
— State vector
real-valued 5-element vector | real-valued 7-element vector | 5-by-N real-valued matrix | 7-by-N real-valued matrix
State vector for a constant turn-rate motion model in two or three spatial dimensions, specified as a real-valued vector or matrix.
When specified as a 5-element vector, the state vector describes 2-D motion in the x-y plane. You can specify the state vector as a row or column vector. The components of the state vector are
[x;vx;y;vy;omega]
wherex
represents the x-coordinate andvx
represents the velocity in the x-direction.y
represents the y-coordinate andvy
represents the velocity in the y-direction.omega
represents the turn rate.When specified as a 5-by-N matrix, each column represents a different state vector N represents the number of states.
When specified as a 7-element vector, the state vector describes 3-D motion. You can specify the state vector as a row or column vector. The components of the state vector are
[x;vx;y;vy;omega;z;vz]
wherex
represents the x-coordinate andvx
represents the velocity in the x-direction.y
represents the y-coordinate andvy
represents the velocity in the y-direction.omega
represents the turn rate.z
represents the z-coordinate andvz
represents the velocity in the z-direction.When specified as a 7-by-N matrix, each column represents a different state vector. N represents the number of states.
Position coordinates are in meters. Velocity coordinates are in meters/second. Turn rate is in degrees/second.
Example: [5;0.1;4;-0.2;0.01]
Data Types: double
frame
— Measurement output frame
'rectangular'
(default) | 'spherical'
Measurement output frame, specified as 'rectangular'
or
'spherical'
. When the frame is 'rectangular'
,
a measurement consists of x, y, and
z Cartesian coordinates. When specified as
'spherical'
, a measurement consists of azimuth, elevation,
range, and range rate.
Data Types: char
sensorpos
— Sensor position
[0;0;0]
(default) | real-valued 3-by-1 column vector
Sensor position with respect to the navigation frame, specified as a real-valued 3-by-1 column vector. Units are in meters.
Data Types: double
sensorvel
— Sensor velocity
[0;0;0]
(default) | real-valued 3-by-1 column vector
Sensor velocity with respect to the navigation frame, specified as a real-valued 3-by-1 column vector. Units are in m/s.
Data Types: double
laxes
— Local sensor coordinate axes
[1,0,0;0,1,0;0,0,1]
(default) | 3-by-3 orthogonal matrix
Local sensor coordinate axes, specified as a 3-by-3 orthogonal matrix. Each column specifies the direction of the local x-, y-, and z-axes, respectively, with respect to the navigation frame. That is, the matrix is the rotation matrix from the global frame to the sensor frame.
Data Types: double
measurementParameters
— Measurement parameters
structure | array of structure
Measurement parameters, specified as a structure or an array of structures. The fields of the structure are:
Field | Description | Example |
---|---|---|
Frame | Frame used to report measurements, specified as one of these values:
Tip In Simulink, when you create an object detection Bus, specify
| 'spherical' |
OriginPosition | Position offset of the origin of the frame relative to the parent frame, specified as an [x y z] real-valued vector. | [0 0 0] |
OriginVelocity | Velocity offset of the origin of the frame relative to the parent frame, specified as a [vx vy vz] real-valued vector. | [0 0 0] |
Orientation | Frame rotation matrix, specified as a 3-by-3 real-valued orthonormal matrix. | [1 0 0; 0 1 0; 0 0 1] |
HasAzimuth | Logical scalar indicating if azimuth is included in the measurement. This
field is not relevant when the | 1 |
HasElevation | Logical scalar indicating if elevation information is included in the measurement. For
measurements reported in a rectangular frame, and if
HasElevation is false, the reported measurements assume 0
degrees of elevation. | 1 |
HasRange | Logical scalar indicating if range is included in the measurement. This
field is not relevant when the | 1 |
HasVelocity | Logical scalar indicating if the reported detections include velocity measurements. For a
measurement reported in the rectangular frame, if HasVelocity
is false , the measurements are reported as [x y
z] . If HasVelocity is true ,
the measurement is reported as [x y z vx vy vz] . For a
measurement reported in the spherical frame, if HasVelocity
is true , the measurement contains range-rate
information. | 1 |
IsParentToChild | Logical scalar indicating if Orientation performs a frame rotation from the parent coordinate frame to the child coordinate frame. When IsParentToChild is false , then Orientation performs a frame rotation from the child coordinate frame to the parent coordinate frame. | 0 |
If you only want to perform one coordinate transformation, such as a transformation from the body frame to the sensor frame, you only need to specify a measurement parameter structure. If you want to perform multiple coordinate transformations, you need to specify an array of measurement parameter structures. To learn how to perform multiple transformations, see the Convert Detections to objectDetection Format (Sensor Fusion and Tracking Toolbox) example.
Data Types: struct
Output Arguments
measurementjac
— Measurement Jacobian
real-valued 3-by-5 matrix | real-valued 4-by-5 matrix
Measurement Jacobian, returned as a real-valued 3-by-5 or 4-by-5
matrix. The row dimension and interpretation depend on value of the frame
argument.
Frame | Measurement Jacobian |
---|---|
'rectangular' | Jacobian of the measurements [x;y;z] with
respect to the state vector. The measurement vector is with respect
to the local coordinate system. Coordinates are in meters. |
'spherical' | Jacobian of the measurement vector [az;el;r;rr] with
respect to the state vector. Measurement vector components specify
the azimuth angle, elevation angle, range, and range rate of the object
with respect to the local sensor coordinate system. Angle units are
in degrees. Range units are in meters and range rate units are in
meters/second. |
More About
Azimuth and Elevation Angle Definitions
Define the azimuth and elevation angles used in the toolbox.
The azimuth angle of a vector is the angle between the x-axis and its orthogonal projection onto the xy plane. The angle is positive in going from the x axis toward the y axis. Azimuth angles lie between –180 and 180 degrees. The elevation angle is the angle between the vector and its orthogonal projection onto the xy-plane. The angle is positive when going toward the positive z-axis from the xy plane.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2021a
See Also
Functions
constacc
|constaccjac
|cameas
|cameasjac
|constturn
|constturnjac
|ctmeas
|constvel
|constveljac
|cvmeas
|cvmeasjac
Objects
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