Page 144 - Practical Control Engineering a Guide for Engineers, Managers, and Practitioners

A New Do11ai1 a1d ltre Precess ltdels ll9

of the controlled system to deal with disturbances or noise N of dif-
ferent frequencies.
The pure dead-time process and the first-order with dead-time or
FOWDT process were introduced and the frequency domain analysis
was applied. Because of the dead time, both processes could become
unstable if the controller parameters were aggressive. Experience has
shown that the FOWDT model is often a good approximation to
industrial processes. It has the overall qualitative response of most
processes and it is a good test for control algorithms because it can
become unstable in a closed-loop configuration.
In the next chapter more processes and a new mathematical tool,
matrices, will be introduced.