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., robstab) do not handle these types of uncertain elements.

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: [2×3 ss]
    AutoSimplify: 'basic'
            Name: 'm'
              Ts: 0
        TimeUnit: 'seconds'
       InputName: {3×1 cell}
       InputUnit: {3×1 cell}
      InputGroup: [1×1 struct]
      OutputName: {2×1 cell}
      OutputUnit: {2×1 cell}
     OutputGroup: [1×1 struct]
           Notes: [0×1 string]
        UserData: []