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my field is not that much related to, but I need to build a model-based simulation in simulink. The model has a transfer modified function as follows:

r(s)/q(s)=t/(t*s+1)

I know the basics, however, to implement this, I got into question, whether I have to use a Gain block with value of t before and after a transfer function like this 1/(s+1), or it should be implemented in another fashion? As t is not a constant. Thanks.

Gerard
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  • So is `t` a variable time constant, or is it time? Either way, if it's variable you won't be able to use a `Constant` block, and neither will you be able to use `1/(s+1)`. You'll have to build a model using an `Integrator`, `sum`, and `Product` block. – Phil Goddard Sep 27 '19 at 17:41
  • It is a variable, i.e., it is travel time that depends on speed (v) which itself is one of the outputs of the model. Can you explain how they should be used, and what is the role of `sum` block? – Gerard Sep 27 '19 at 19:22

1 Answers1

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Firstly note that t/(t*s + 1) is equivalent to 1/(s+(1/t)). In both cases t > 0 or the system is unstable or ill-defined.

If t was constant then you could use a Transfer Function block, which is the equivalent of the first of the following implementations. Since t is not constant, you cannot use a Transfer Function block, but you can use the second implementation shown below.

First order transfer functions

Phil Goddard
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