WM273_Lecture_1_-_Process_Control

Control

The process of altering the performance of a system.

Process Control

Activities involved in ensuring that a process is predictable, stable, and consistently operating at the target level of performance.

Regulation

To maintain a selected output variable constant despite disturbances.

Tracking

The ability to make the regulated output variable follow a variable setting.

Sequencing

Making events happen in a specific order, either time-driven or event-driven.

Closed-loop control

Controlling action influenced by the output, where requested output is compared to the measured output.

Open-loop control

Controlling input that is not influenced by the output.

Setpoint

A desired value for a process variable that is maintained.

Servomechanisms

Control systems that move controlled elements to follow variations of a reference value.

Discrete-State Control Systems

Control systems that manage a sequence of events rather than regulating a single variable.

Analog Data

Data representing variables with a smooth, continuous variation.

Digital Data

Data represented in numbers as binary digits (1s and 0s).

Analog-to-Digital Converter (ADC)

Device that converts analog voltages into a digital representation.

Digital-to-Analog Converter (DAC)

Device that converts digital control output into an analog form.

Cyclic Response

Output variable exhibits oscillations about the reference value.

Damped Response

Aperiodic response characterized by a single polarity error that never oscillates around the setpoint.

Maximum Error (e)

The greatest deviation from the desired setpoint during system regulation.

Transient Regulation

How a control system reacts to sudden changes or large variations.

Tuning

Adjusting a process-control loop to provide the best control.

Programmable Logic Controllers (PLCs)

Self-contained microcomputers optimized for industrial control.