Block 1 - lecture 1

Question 1

What’s control?

Answer 1

altering the performance of a system

Question 2

What are the possible aims of control?

Answer 2

• regulate output
• tracking a varying value
• time/event driven sequencing

Question 3

Benefits of process control?

Answer 3

• predictable
• stable
• constant

Question 4

Purpose of sensor?

Answer 4

to measure output

Question 5

Purpose of actuator?

Answer 5

to adjust input

Question 6

Purpose of controller?

Answer 6

coordinates sensors and actuators

Question 7

Setpoint?

Answer 7

a value to be maintained

Question 8

Discrete-state control systems?

Answer 8

sequence of on/off events

Question 9

Open loop control?

Answer 9

input isn’t controlled by the output (input on = output on)

Question 10

Closed-loop control?

Answer 10

input is influenced by the output (eg. thermostat)

Question 11

Question to ask before choosing closed-loop control?

Answer 11

• really needed?
• input measureable?
• save energy?
• easy to set up/maintain?
• safe?

Question 12

What are the objectives of control systems?

Answer 12

• stable
• steady state regulation
• transient regulation

Question 13

What desired quality of a control system can reduce stability?

Answer 13

faster responses

Question 14

Steady state error?

Answer 14

difference between output and input at steady state

Question 15

Transient response?

Answer 15

how the system reacts to change

Question 16

What’s tuning?

Answer 16

adjusting a process-control loop

Question 17

2 ways to measure transient response?

Answer 17

• response to change of setpoint

- response to transient disturbance

Question 18

types of response?

Answer 18

• damped

- cyclic

Question 19

features of a cyclic response?

Answer 19

• overshoot (step input change/first overshoot)
• decay rate (second overshoot/first)
• rise time (time for step change)
• settling time

Question 20

Cyclic response with quarter amplitude?

Answer 20

decay rate of 1/4

Question 21

Aims of cyclic tuning?

Answer 21

• reduce area either side of setpoint after rise time
• reduce decay rate
• time rise

Question 22

Analog vs digital processing?

Answer 22

• analog is smooth

- digital has steps

Question 23

ADC?

Answer 23

Analog to digital convertor

Question 24

DAC?

Answer 24

Digital to analog convertor

Question 25

Bi-directional on/off control system?

Answer 25

max on, no effort, max off

Question 26

Analog control system?

Answer 26

continuously variating input/output

Question 27

Supervisory control?

Answer 27

still analog, computer monitors the output

Question 28

Direct digital control?

Answer 28

computer is fed the output and generates the input

Can give error detection

Question 29

LAN?

Answer 29

Local Area Networks

Question 30

PLCs?

Answer 30

Programmable logic controllers (self contained microcomputer)