cvmeasmsc
Measurement based on constant velocity (CV) model in MSC frame
Syntax
Description
provides the angular measurement (azimuth and elevation) of the state in the sensor frame
described by the measurement
= cvmeasmsc(state
)state
.
Tracking filters require a definition of the MeasurementFcn
property. The cvmeasmsc
function can be used as the
MeasurementFcn
. To use this MeasurementFcn
with
trackerGNN
and
trackerTOMHT
, you
can use the trackingMSCEKF
filter.
provides the measurement in the frame specified. The allowed values for
measurement
= cvmeasmsc(state
,frame
)frame
are 'rectangular'
and
'spherical'
.
specifies the axes of the sensor's coordinate system. The measurement
= cvmeasmsc(state
,frame
,laxes
)laxes
input
is a 3-by-3 matrix with each column specifying the direction of local x,
y and z axes in the observer's Cartesian frame. The
default for laxes
is [1 0 0;0 1 0;0 0 1
].
specifies the measurement parameters as a scalar struct or an array of struct.measurement
= cvmeasmsc(state
,measurementParameters
)
[
returns the measurement bounds, used by a tracking filter (measurement
,bounds
] = cvmeasmsc(___)trackingEKF
, trackingUKF
, trackingCKF
,trackingIMM
, trackingMSCEKF
, or trackingGSF
) in residual
calculations.
Examples
Obtain Measurements in MSC Frame
Using the cvmeasmsc
function, you can obtain measurements of the state in the spherical and the rectangular frames.
Spherical Frame
Obtain the azimuth and elevation measurements from an MSC state.
mscState = [0.5;0;0.3;0;1e-3;1e-2]; cvmeasmsc(mscState)
ans = 2×1
28.6479
17.1887
Rectangular Frame
Obtain the position measurement from an MSC state. Specify the frame as a second input.
cvmeasmsc(mscState,'rectangular')
ans = 3×1
838.3866
458.0127
295.5202
Alternatively, you can specify the frame using measurementParameters
.
cvmeasmsc(mscState,struct('Frame','rectangular'))
ans = 3×1
838.3866
458.0127
295.5202
Display Residual Wrapping Bounds for cvmeasmsc
Specify a 3-D state and specify a measurement structure such that the function outputs azimuth and elevation measurements.
state = [pi/2 .3 pi/6 0.1 1 0]'; % [az omega el elRate 1/r vr/r] mp = struct("Frame","Spherical", ... "HasAzimuth",true, ... "HasElevation",true);
Output the measurement and wrapping bounds using the cvmeasmsc
function.
[measure,bounds] = cvmeasmsc(state,mp)
measure = 2×1
90
30
bounds = 2×2
-180 180
-90 90
Input Arguments
state
— Relative state
vector | matrix
State that is defined relative to an observer in modified spherical coordinates,
specified as a vector or a 2-D matrix. For example, if there is a constant velocity
target state, xT, and a constant velocity observer state,
xO, then the state
is defined as xT -
xO transformed in modified spherical coordinates.
The two-dimensional version of modified spherical coordinates (MSC) is also referred to as the modified polar coordinates (MPC). In the case of:
2-D space –– State is equal to [az azRate 1/r vr/r].
3-D space –– State is equal to [az omega el elRate 1/r vr/r].
The variables used in the convention are:
az –– Azimuth angle (rad)
el –– Elevation angle (rad)
azRate –– Azimuth rate (rad/s)
elRate –– Elevation rate (rad/s)
omega –– azRate × cos(el) (rad/s)
1/r –– 1/range (1/m)
vr/r –– range-rate/range or inverse time-to-go (1/s)
If the input state is specified as a matrix, states must be concatenated along columns, where each column represents a state following the convention specified above. The output is a matrix with the same number of columns as the input, where each column represents the measurement from the corresponding state.
If the motion model is in 2-D space, values corresponding to elevation are assumed to be zero if elevation is requested as an output.
Data Types: single
| double
frame
— Measurement frame
'spherical'
(default) | 'rectangular'
Measurement frame, specified as 'spherical'
or
'rectangular'
. If using the 'rectangular'
frame,
the three elements present in the measurement represent x,
y, and z position of the target in the
observer's Cartesian frame. If using the 'spherical'
frame, the two
elements present in the measurement represent azimuth and elevation measurement of the
target. If not specified, the function provides the measurements in
'spherical'
frame.
laxes
— Direction of local axes
[1 0 0;0 1 0;0 0 1]
(default) | 3-by-3 matrix
Direction of local x, y, and
z axes in the scenario, specified as a 3-by-3 matrix. If not
specified, laxes
is equal to [1 0 0;0 1 0;0 0
1]
.
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 example.
Data Types: struct
Output Arguments
measurement
— Measurement from MSC state
vector
Target measurement in MSC frame, returned as a:
One-element vector –– When
HasElevation
is set tofalse
, the vector contains azimuth as the only measurement.Two-element vector –– When the
frame
is set to'spherical'
, the function measures the azimuth and elevation measurements from an MSC state.Three-element vector –– When the
frame
is set to'rectangular'
, the function measures the position measurement from an MSC state.
bounds
— Measurement residual wrapping bounds
M-by-2 real-valued matrix
Measurement residual wrapping bounds, returned as an M-by-2
real-valued matrix, where M is the dimension of the measurement. Each
row of the matrix corresponds to the lower and upper bounds for the specific dimension
in the measurement
output.
The function returns different bound values based on the frame
input.
If the
frame
input is specified as'Rectangular'
, each row of the matrix is[-Inf Inf]
, indicating the filter does not wrap the measurement residual in the filter.
If the
frame
input is specified as'Spherical'
, the returnedbounds
contains at least one row of the azimuth bounds as[-180 180]
, indicating the filter wraps the azimuth residual in the range of[-180 180]
in degrees. Optionally, whenHasElevation
=true
, the matrix includes a second row of[-90 90]
, indicating the filter wraps the elevation residual in the range of[-90 90]
in degrees.
The filter wraps the measurement residuals based on this equation:
where x is the residual to wrap, a is the lower bound, b is the upper bound, mod is the modules after division function, and xwrap is the wrapped residual.
Data Types: single
| double
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
Version History
Introduced in R2018b
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