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controller then reads the reaction of these test signals on the process.
Keep in mind that every process is different and therefore every reac-
tion to the test signals is different. This is why PID parameters are not
the same for all processes. The amplitude (L) or lag time which is the
overshoot and undershoot of the system when autotuning, and the time
constant (T) which is the time the process takes to go through one
On/Off cycle are measured. See diagram below.
The measurements are then used with the Autotune algorithm for cal-
culation of the proper PID parameters for the system, as shown below,
where K is the proportionality constant and S is the Laplace operator.
K
e-LS
(1+TS)