Simulink Control Design™ - MathWorks

(Tuis.) #1
If the tuning goal constrains a MIMO transfer function, scalar or SISO weighting
functions automatically expand to any input or output dimension. You can specify different
weights for each channel by specifying matrices or MIMO weighting functions. The
dimensions H(s) must be commensurate with the dimensions of WL and WR. For example,
if the constrained transfer function has two inputs, you can specify diag([1 10]) as
WR.

If you are tuning in discrete time, you can specify the weighting functions as discrete-time
models with the same sampling time as you use for tuning. If you specify the weighting
functions in continuous time, the tuning software discretizes them. Specifying the
weighting functions in discrete time gives you more control over the weighting functions
near the Nyquist frequency.

Options


Use this section of the dialog box to specify additional characteristics of the step response
goal.


  • Minimum input passivity index


Enter the target value of ν in the text box. To enforce an excess of passivity at the
specified inputs, set ν > 0. To permit a shortage of passivity, set ν < 0. By default, the
passivity goal enforces ν = 0, passive at the inputs with no required excess of
passivity.


  • Minimum output passivity index


Enter the target value of ρ in the text box. To enforce an excess of passivity at the
specified outputs, set ρ > 0. To permit a shortage of passivity, set ρ < 0. By default, the
passivity goal enforces ρ = 0, passive at the outputs with no required excess of
passivity.


  • Enforce goal in frequency range


Limit the enforcement of the tuning goal to a particular frequency band. Specify the
frequency band as a row vector of the form [min,max], expressed in frequency units
of your model. For example, to create a tuning goal that applies only between 1 and
100 rad/s, enter [1,100]. By default, the tuning goal applies at all frequencies for
continuous time, and up to the Nyquist frequency for discrete time.


  • Apply goal to


Use this option when tuning multiple models at once, such as an array of models
obtained by linearizing a Simulink model at different operating points or block-

10 Control System Tuning

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