Systems with Unmodeled Dynamics

The unstructured uncertain dynamic system Control Design Block, the udyn object, represents completely unknown multivariable, time-varying nonlinear systems.

For practical purposes, these uncertain elements represent noncommuting symbolic variables (placeholders). All algebraic operations, such as addition, subtraction, multiplication (i.e., cascade) operate properly, and substitution (with usubs) is allowed. However, all of the analysis tools (e.g., robuststab) do not handle these types of uncertain elements. As such, these elements do not provide a significant amount of usability, and their role in the user's guide is small.

You can create a 2-by-3 udyn element. Check its size, and properties.

m = udyn('m',[2 3]) 
m =

  Uncertain dynamics "m" with 2 outputs and 3 inputs.
get(m) 
    NominalValue: [2x3 ss]
    AutoSimplify: 'basic'
              Ts: 0
        TimeUnit: 'seconds'
       InputName: {3x1 cell}
       InputUnit: {3x1 cell}
      InputGroup: [1x1 struct]
      OutputName: {2x1 cell}
      OutputUnit: {2x1 cell}
     OutputGroup: [1x1 struct]
            Name: 'm'
           Notes: {}
        UserData: []
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