User`s guide

Identifying Low-Order Transfer Functions (Process M odels)
estimatio n settin gs for one in put, select a differe nt input in the Input
Number list.
If you want the same transfer fun cti on to apply to all inputs, select the Same
structure for all channels check b ox. To apply a different structure to each
channel, leave this check box clear, and create a different transfer function for
each input.
At the command line. Specify the model structure as a cell a rray of acronym
strings in the estimation command
pem. For example, use this command to
specify the first-order transfer function for the first input, and a second-order
model with a zero and an integrator for the second input:
m = idproc({'P1','P2ZI'})
m = pem(data,m)
To apply the same structure to all inputs, define a single structure in idproc.
Options for the Disturbance Model Structure
This section describes how to specify a noise model in the estimation
procedures “How to Estimate Process Models Using the GUI” on page 3-23
and “Estimating Process Models at the Command Line” on page 3-29.
In addition to the transfer function G, a linear system can include an additive
noise term He,asfollows:
yGuHe=+
where e is white noise.
You can estimate only the dynamic model G, or estimate both the dynamic
model and the disturbance model H. For process models, H is a rational
transfer function C/D,wheretheC and D polynomials for a first- or
second-order ARMA model.
In the GUI. To specify whether to include or exclude a noise model in the
Process M o de ls dialog box, select one of the following options from the
Disturbance Model list:
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