Proportional-Integral-Derivative (PID) control is used in more than 99% of the loops for chemical, pharmaceutical, and food and beverage production. PID has proven to be capable of the best load rejection by using the best tuning and the extensive flexibility of functionality offered by the PID structure and options, most notably external-reset feedback. Bohl and McAvoy enlightened us about it in a 1976 landmark paper, “Linear Feedback vs. Time Optimal Control, II. The Regulator Problem” (Industrial & Engineering Chemistry, Process Design and Development, Vol. 15, No. 1, 1976, p. 30-33).The opening challenge with PID control is recognizing the effect of PID form,…
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