Question

What is proportional-integral-derivative (PID)?

(a) Bioreactor

(b) Controller

(c) Mathematical integration

(d) Mathematical differentiation

I had been asked this question in an interview for internship.

The above asked question is from Monitoring and Control of Bioreactors in division Reactor Engineering of Bioprocess Engineering

Answer 1

The correct answer is:

(b) Controller

Explanation: A Proportional-Integral-Derivative (PID) controller is a control loop mechanism widely used in industrial control systems. It continuously calculates the error value as the difference between a desired setpoint and a measured process variable, and applies a correction based on proportional, integral, and derivative terms. These three components help to control and adjust the output in such a way that the process reaches and maintains the desired setpoint:

• Proportional: Adjusts the output based on the current error.
• Integral: Corrects past accumulated errors.
• Derivative: Predicts future error based on the rate of change.

In the context of bioreactor systems, a PID controller is often used to regulate parameters like temperature, pH, oxygen concentration, and agitation speed to maintain optimal conditions for the growth of microorganisms or cells in the bioreactor.