to compare the floating value of a signal with file.mat signal

Hi,

In a simulink simulation i've "recorded" a signal in a file.mat. Now, in an other simulation i need to compare a new signal with file.mat-signal (i'll call file.mat-signal as m(t)).

For example with the floating value f(t) of the new signal (in the new simulation) i need to know the time t such that:

abs(f(t)-m(t)) < some tolerance value

I know that t is an element of the file.mat matrix, but i don't know how i can do the comparison in simulink.

Answer 1

[Seth Popinchalk]

You can build the equation using blocks from the Math Operations and Logic and Bit Operations libraries.

You will need an ABS block, a Sum Block and you could use the Compare to Constant to make the comparison to the tolerance value. This produces a signal that will be 1 when the condition is true. That can be used to trigger or enable a conditionally executed subsystem.

[cyberdyne]

I've some problem to make it read file.mat. I don't know why the blocks don't see From File Block output like a constant matrix as it is.

If i build

abs(f(t)-m(t)) < some tolerance value

How can i meet "t value" that respect condition above ?

[Kaustubha Govind]

Does your data in the MAT-file conform to the required format for From File (see http://www.mathworks.com/help/toolbox/simulink/slref/fromfile.html)? Also see the heading "Simulation Time Hits That Have No Corresponding MAT-File Time Stamps".

[cyberdyne]

I've loaded mat-file. Inside it there are time value with 1s decimation (0 1 2 3...) as 1st row and there are signal value samples as 2nd row. If i plot 1st row-->2nd row, it returns me original signal as it is.

I tried to record time of the 1st simulation in an other mat-file and:

FromFile(time.mat)----->SubSystem(with Trig.)---->display

FromFile(Signal.mat)---(+)>Sum--->ABS---CompareToConst.(<0.01)-->trig.

SignalToCompare--------(-)|

But display doesn't show value of time of time.mat