State prediction equation for Kalman filter

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Discussion Overview

The discussion revolves around the formulation of state prediction equations for a Kalman filter, particularly in the context of translating a transfer function into state space representation. Participants explore the necessary matrices involved in the Kalman filter and their application in simulating data filtering from a barometer.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about how to derive the state prediction equation from the given transfer function and suggests the need for state space representation.
  • Another participant advises determining the A, B, C, and D matrices and suggests creating a block diagram to visualize the system.
  • A different participant asserts that translating a transfer function to matrix form should be straightforward for those familiar with Kalman filters and linear algebra.
  • A participant who identifies as a programmer rather than an engineer shares their findings of the A, B, C, and D matrices using MATLAB and describes their intention to simulate filtering data from a barometer.
  • This participant questions the role of the transfer function in their simulation and whether it indicates how barometer data changes over iterations, expressing confusion about the necessity of random pressure data versus using data from the transfer function.
  • Another participant responds by reiterating the existence of the transfer function and emphasizes the importance of understanding the covariance matrix of noise before proceeding with measurements.
  • This participant encourages the calculation of state and covariance predictions based on the established matrices.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the role of the transfer function in the simulation or the necessity of using random pressure data. There are competing views on how to approach the problem of deriving the state prediction equation and the relevance of the transfer function in this context.

Contextual Notes

Participants express varying levels of familiarity with engineering concepts, which may influence their understanding of the Kalman filter and its implementation. There are unresolved questions regarding the integration of the transfer function into the simulation process.

evol_w10lv
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I have to filter data with Kalman filter. I know process error covariance Q and measurment error covariance R. Problem is with state transition matrix A, control matrix B and observation matrix H.

First of all, data goes through this transfer function:
##W(s) = \frac{4s}{4s+1}##
I can't get it how to write state prediction equation from transfer function. Maybe to write state prediction equation for Kalman filter, I need to write state space representation like HERE?
 
You need to first find out what your A,B,C, and D matricies are.
It can help to generate a block diagram of your system with the proposed measurements (ie kalman filter)
 
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If you are working with kalman filters, you should be able to translate a transfer function to matrix form no problem. If not, you need to take a very good look at linear algebra
 
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Sorry for late response.
I don't work in the engineering sector. I prefer programming. I am familiar with Kalman filter in programming level. Here my problem is in basics of engineering.
I found out ##A, B, C, D## with MATLAB built in function:
##x(k+1)=-0.25*x(k) + 1*u(k)##
##y(k)=1*x(k)##
##A= -0.25, B = 1, C = 1, D = 0##
Let's say I want to simulate filtering data from barometer with Kalman filter, then calculate change of height, derive it to get vertical speed. It's just imitation.. no real device.
My idea was to generate random pressure data from barometer, then calculate height using formula and use Kalman filter with parameters:
$$ A = \begin{bmatrix}
1 & dt \\
0 & 1 \
\end{bmatrix}
H=
\begin{bmatrix}
1 \\
0
\end{bmatrix}
$$
But there isn't transfer function inculded. It's not clear what are functions of TF in this case. Is it shows how barometer data changes in each iteration? So no need to use random pressure data (but use data from TF if I give initial value before) or ...?
 
evol_w10lv said:
But there isn't transfer function inculded. It's not clear what are functions of TF in this case. Is it shows how barometer data changes in each iteration? So no need to use random pressure data (but use data from TF if I give initial value before) or ...?
To be honest I have no idea what you are asking?
You already listed the transfer function W(s) above. Why are you asking me what it is?
You should have some idea of the covarience matrix of your noise. If you don't, you need to work on your model before you can make a measurement filter

You worked out what the A and B matrixes are. You should now be able to calculate your state and covarience predictions.

Then you can calculate your observations, then update the values to use in the next iteration.
 

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