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This set of notes
presented very briefly, the principles behind the design of
simple digital controllers. From the preceding pages, there
are several key points to note:
-
Essentially,
digital controllers are designed based on process models,
and with very few exceptions, the designs begin with the
specification of some desired closed loop properties.
-
Different
controllers of different complexities will result, depending
on the criterion and the form of the process model. This
set of notes introduced the use of the Synthesis
Equation to derive model based controllers.
-
While the
focus has been on the dead-beat
and Dahlin controllers, many
of their features and limitations
can be found in other modern control algorithms.
-
One of these,
the pole-placement controller,
was briefly mentioned not only to show that other design
methods are possible, but to also show that these are all
related in some manner.
-
At the end
of the day, given a firm grasp of the basics and armed with
the necessary mathematical and simulation tools, numerous
digital controllers that are able to perform various tasks
can be formulated. The proof of the pudding is whether the
candidate controller is robust enough to be implemented
safely on real processes, with their inherent non-linear
characteristics and time-varying behaviour.
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