How can I ignore (delete) unwanted peaks of a continious signal?

Hey, i have a signal with peaks (frequency of them is not constant) and goal is to just go over it in a straigt line. The system is build in simulink and i tryed different filter, but didnt' succed. Any ideas?

It is the curve of the speed of a motor and i would like to get a straigt line (red) instead of an overshoot.

Thanks for your help.

Best regards.

[Paul]

Hi Emefun,

Do you mean that you want to modify the input to the motor such that that there are no transients in the motor speed response once it reaches (near) steady state?

Or are you using the motor speed as an input to another subsystem downstream and you just don't want that subsystem to "see" those transients?

Or something else?

[Emefun]

Hi, i just want that the system cant see these peaks, the system should handle it like a straight line. But the amplitude should be able to rise if the system needs a higher velocity of the motor

[Emefun]

The peaks occur, cause of the subsystem and I cant eliminate them

[Paul]

"i just want that the subsystem cant see these peaks, the system should handle it like a straight line"

Which subsystem and which system?

Maybe a screen capture of the relevant porition of the block diagram would be helpful. If want to post a screen capture, you can use the Image icon on the Insert menu (to the left of the Link icon).

[Emefun]

i dont have access to it until tuesday to send a screenshot, but I can try to explain.

I get the velocitycurve of the motor with disturbances from a subsystem. I should transfer this curve without the disturbance-peaks into my system.

It is just important, that the system don't get the peaks. It would be instable then.

[Emefun]

@Paul

Answer 1

[John D'Errico]

Just choose some point where the curve should have settled into its long term nominal state. That should be at or about a time of 25 in your plot.

Next, take the median value of the curve over that interval, here from a time of 25 to the end.

help median

 MEDIAN Median value.
    For vectors, MEDIAN(x) is the median value of the elements in x.
    For matrices, MEDIAN(X) is a row vector containing the median value
    of each column.  For N-D arrays, MEDIAN(X) is the median value of the
    elements along the first non-singleton dimension of X.
 
    MEDIAN(X,"all") is the median of all elements of X.
 
    MEDIAN(X,DIM) takes the median along the dimension DIM of X.
 
    MEDIAN(X,VECDIM) operates on the dimensions specified in the vector 
    VECDIM. For example, MEDIAN(X,[1 2]) operates on the elements contained
    in the first and second dimensions of X.
 
    MEDIAN(...,NANFLAG) specifies how NaN values are treated:
 
    "includemissing" / "includenan" -
                   (default) The median of a vector containing NaN values
                   is also NaN.
    "omitmissing" / "omitnan"       -
                   The median of a vector containing NaN values is the
                   median of all its non-NaN elements. If all elements
                   are NaN, the result is NaN.
 
    Example:
        X = [1 2 4 4; 3 4 6 6; 5 6 8 8; 5 6 8 8]
        median(X,1)
        median(X,2)
 
    Class support for input X:
       float: double, single
       integer: uint8, int8, uint16, int16, uint32, int32, uint64, int64
 
    See also MEAN, STD, MIN, MAX, VAR, COV, MODE.

    Documentation for median
       doc median

    Other uses of median

       categorical/median      prob.NormalDistribution/median
       codistributed/median    tabular/median
       datetime/median         tall/median
       duration/median         timeseries/median
       fixedpoint/median

Finally, discard any value ABOVE that median. You can just use min to perform that task. You might even be more aggressive, and choose the 25th percentile of the curve, as perhaps a better estimate of the long term behavior, better insuring you don't get any of those outlier segments at all.

[Emefun]

hey, thanks for the help.

problem is, that the peak could occur any time. Also the amplitude can get a different value due to requirements of the speed.

Maybe I dont get you right.

[Emefun]

@John D'Errico it got how to use the min block, but it is a continious signal and i dont know how to build this median in simulink then