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constvel

Constant velocity state update

Syntax

updatedstate = constvel(state)
updatedstate = constvel(state,dt)

Description

example

updatedstate = constvel(state) returns the updated state, state, of a constant-velocity Kalman filter motion model after a one-second time step.

example

updatedstate = constvel(state,dt) specifies the time step, dt.

Examples

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Update the state of two-dimensional constant-velocity motion for a time interval of one second.

state = [1;1;2;1];
state = constvel(state)
state = 4×1

     2
     1
     3
     1

Update the state of two-dimensional constant-velocity motion for a time interval of 1.5 seconds.

state = [1;1;2;1];
state = constvel(state,1.5)
state = 4×1

    2.5000
    1.0000
    3.5000
    1.0000

Input Arguments

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Kalman filter state vector for constant-velocity motion, specified as a real-valued 2N-element column vector where N is the number of spatial degrees of freedom of motion. For each spatial degree of motion, the state vector takes the form shown in this table.

Spatial DimensionsState Vector Structure
1-D[x;vx]
2-D[x;vx;y;vy]
3-D[x;vx;y;vy;z;vz]

For example, x represents the x-coordinate and vx represents the velocity in the x-direction. If the motion model is 1-D, values along the y and z axes are assumed to be zero. If the motion model is 2-D, values along the z axis are assumed to be zero. Position coordinates are in meters and velocity coordinates are in meters/sec.

Example: [5;.1;0;-.2;-3;.05]

Data Types: single | double

Time step interval of filter, specified as a positive scalar. Time units are in seconds.

Example: 0.5

Data Types: single | double

Output Arguments

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Updated state vector, returned as a real-valued vector or real-valued matrix with same number of elements and dimensions as the input state vector.

Algorithms

For a two-dimensional constant-velocity process, the state transition matrix after a time step, T, is block diagonal as shown here.

[xk+1vx,k+1yk+1vy,k+1]=[1T000100001T0001][xkvxkykvyk]

The block for each spatial dimension is:

[1T01]

For each additional spatial dimension, add an identical block.

Extended Capabilities

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

Introduced in R2018b