Chemical Process Control

Glossary

Actuator

The mechanical device that cause the activation or movement of a final control element.

Direct Synthesis

Final Control Element

A physical device whose activation or movement causes a change in a dynamic process. In process control, the most common final control elements are control valves.

Frequency Domain

Internal Model Control

IMC-PID Tuning

A method for PID tuning that selects tuning parameters to approximate an IMC-derived controller.

Ladder Logic

A semi-graphical programming language used to represent control algorithms. The language is expressed using symbols for logic devices. The arrangement of the device symbols and their connections has the appearance of a ladder.

Laplace Transform

An integral transformation from time domain to Laplace domain. Given a function of time $f(t)$, the Laplace transform is given by the following

$F(s)=\underset{0}{\overset{\mathrm{\infty }}{\int }}f(t)e^{-st}dt$

The use of $F(s)$ to represent the Laplace transform of $f(t)$ is a common convention; however, in dynamics and control it is common to use $f(t)$ and $f(s)$ to represent a time-domain function and its Laplace transform, respectively.

PID Controller

PLC

Programmable Logic Controller, a microprocessor-based electronic device for implementing control algorithms.

Time Domain

Ziegler-Nichols Tuning