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Topic: Simulink Q: Access to integrated variable
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Didik Soetanto

Posts: 1
Registered: 12/11/04
Simulink Q: Access to integrated variable
Posted: Dec 12, 1996 5:19 PM
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Hi all,

Problem:
I have a Simulink model consisting 3 S-blocks among other things. An
output (a 12x1 array) of these S-blocks is constrained. All elements in
this array must be positive (not an absolute value, but more like a
saturation constraint) even though the derivatives can be negative.

Question:
How do you constraint these values? These are a few things I have tried
(and failed)/thought of:
1. Try to change the values inside a user-defined function. Apparently the
variable is kept by Simulink to itself since the values did change
at the
output of this user-defined function, but the output of the S-block is
unchanged. I even tried to make the variable global!!
2. Same idea as in no. 1. Instead of a user-defined function, I used
Simulink blocks.
3. Same idea as in no. 1 but I placed the constrain inside the S-function.
It changed all the derivatives, but the output is all wrong (and it still
can be negative).

If you have encountered this problem before or/and you have the solution
for it, please e-mail me (preferably) or post it here.

Didik
didik.soetanto@asu.edu





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