Question

A PID controller combines the actions of

• A. Proportional and integral only
• B. Proportional and derivative only
• C. Integral and derivative only
• D. Proportional, integral and derivative

Hint:

Logic Tip: The name is the answer. Proportional, Integral, Derivative. It combines all three!

Answer 1

The Correct Option is D

Concept:
In automatic process control, the PID controller is the industry standard feedback mechanism. It calculates an "error" value (the difference between a desired setpoint and a measured process variable) and applies a correction based on a specific mathematical algorithm.

Step 1: Proportional control applies a correction that is directly proportional to the current size of the error. (Large error = large correction, small error = small correction.)

Step 2: Integral control looks at the history of the error. It sums up the error over time to eliminate any stubborn, long-term offset (steady-state error) that the proportional action couldn't fix.

Step 3: Derivative control predicts the future behavior of the error by looking at its current rate of change. It provides a dampening effect to prevent the system from overshooting the target.

Step 4: The acronym "PID" literally stands for these three distinct mathematical modes of control acting together: Proportional, Integral, and Derivative.