Controller Types

Question 1

Define “Delay time”

Answer 1

The time required for the response toreach half the final value the very first time

Question 2

Define “time constant”

Answer 2

The amount of time for the process variable to reach 63.2% of its final value

Question 3

Define “process dead time”

Answer 3

The period of time that passes between a change in the controller output and a hcange in the process variable being measured

Question 4

What are the types of controllers?

Answer 4

Proportional Control (P)
Proportional Derivative Control (PD)
Proportional Integral Control (PI)
Proportional Integral Derivative Control (PID)

Question 5

Describe P Control

Answer 5

Proportional Control: adjusting the system gain.

Pro: Improve transient performance except overshoot.

Con: Steady state error not affected,

may become unstable with high gain.

Question 6

Describe PI Control

Answer 6

AKA Lag compensator: Average over time the input error.

Pro: Good steady state error.

Con: Bad transient response, specifically overshoot

Question 7

Describe PD Control

Answer 7

AKA Lead Compensator: Determines the rate of change of the error signal.

Pro: Good transient response

Con: No impact on steady state error.

High frequency noise introduced to system.

Question 8

Describe PID with Pros and Cons

Answer 8

Lead-lag compensator: Uses both integration and derivation

Good transiet response and steady state response

Question 9

Answer 9

Question 10

P, I, D in future and past terms

Answer 10

P: Present
I: Integral
D: Future