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Payam
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The states gets changed while observing

Asked by Payam
on 26 Sep 2017
Latest activity Answered by Payam
on 26 Sep 2017
Hi, I have an control input T that goes straight to a system. In that system I solve a differential equation system with form of x' = Ax + bu; A and B are defined.I try to observe the states again using two first states x1 and x2. They goe straight to a observer . The observer has a gain that I can modify. When I change the gain of observer the real values that are coming from the plant itself changes. I have no idea why.
I dont know why the gain affects the real value since the gain is not presented anywhere in the plant itself. When I try the plant with out the observer it works fine. I don't know how they get changed. Anyone that can give me a hint. Ive been working on this in 7 days and it drives me crazy.
It the observer subsystem I have in one block used the states x1 and x2 that I renamed to y1 and y2
That is the only place I used x1 and same thing for x2. Why do they get changed while using observer. OBS that they are real values and not estimated. they are the output of the plant. x_1 however is the observed one.

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1 Answer

Answer by Payam
on 26 Sep 2017
 Accepted Answer

The reason is actually the time line or time series. I send the results to workspace and I saw that the time samples are different that is why the curve might seem not like each other. Adn that is becouse gain of the observer makes simulink operate in different values of time. but the result are the same. I reduced the tolerance to 1e-4 and set the mode to Normal. And it worked like a charm. so the blocks are not wrong and the time is not either.

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