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Natural frequency bound


Specify bounds on the natural frequency of the poles of a linear system. You can then optimize the model response to meet these bounds using sdo.optimize.

You must have Simulink® Control Design™ software to specify natural frequency requirements.




pznatfreq_req = sdo.requirements.PZNaturalFrequency creates a sdo.requirements.PZNaturalFrequency object and assigns default values to its properties.

pznatfreq_req = sdo.requirements.PZNaturalFrequency(Name=Value) specifies one or more properties using name-value arguments. For example, pznatfreq_req = sdo.requirements.PZNaturalFrequency(FrequencyUnits="Hz") creates an sdo.requirements.PZNaturalFrequency object and specifies the FrequencyUnits property as hertz.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes. For example, pznatfreq_req = sdo.requirements.PZNaturalFrequency("FrequencyUnits","Hz") creates an sdo.requirements.PZNaturalFrequency object and specifies the FrequencyUnits property as hertz.


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Requirement description, specified as a character vector.

Example: 'Requirement on signal 1'

Frequency units of the requirement, specified as one of the following. The PZNaturalFrequency object stores the value as a character vector.

  • "Hz"

  • "rad/s"

  • "rpm"

  • "kHz"

  • "MHz"

  • "GHz"

  • "rad/nanosecond"

  • "rad/microsecond"

  • "rad/millisecond"

  • "rad/minute"

  • "rad/hour"

  • "rad/day"

  • "rad/week"

  • "rad/month"

  • "rad/year"

  • "cycles/nanosecond"

  • "cycles/microsecond"

  • "cycles/millisecond"

  • "cycles/hour"

  • "cycles/day"

  • "cycles/week"

  • "cycles/month"

  • "cycles/year"

Requirement name, specified as a character vector.

Natural frequency bound, in radians/second, specified as a positive finite scalar.

Natural frequency bound type, specified as one of the following values:

  • "<=" — Upper bound

  • ">=" — Lower bound

  • "==" — Equality bound

  • "max" — Maximization objective

Object Functions

copyCopy design requirement
getGet design requirement property values
setSet design requirement property values
evalRequirementEvaluate design requirement


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Create a natural frequency object and then specify the natural frequency.

r = sdo.requirements.PZNaturalFrequency;
r.NaturalFrequency = 1;

Alternatively, you can specify the natural frequency when you create the object.

r = sdo.requirements.PZNaturalFrequency(NaturalFrequency=1)
r = 
  PZNaturalFrequency with properties:

    NaturalFrequency: 1
                Type: '>='
                Name: ''
         Description: ''
      FrequencyUnits: 'rad/s'


Use getbounds to get the bounds specified in a Check Pole-Zero Characteristics (Simulink Control Design) block.

Version History

Introduced in R2010b