Section 1

Question 1

Define Hierarchical Control

Answer 1

Organizing control objectives with different priorities

Question 2

Multivariable Control

Answer 2

Control of systems with multiple variables. The aim is often to decouple these variables.

Question 3

Optimal Control

Answer 3

Optimal controllers complete objectives whilst minimizing a performance index.

Question 4

What is classic control?

Answer 4

Continuous time, Laplace transforms, Mechanistic models, frequency domain techniques, root locus, PID control
They are traditional, familiar and simple!

Question 5

What is modern control?

Answer 5

Discrete time, data based models, state variable feedback, predictive and optimal control.
improved performance, objective optimized, adaptive control and multi variable decoupling

Question 6

What are the benefits of closed loop control over open loop?

Answer 6

By adding feedback the algorithm can “automatically” deal with disturbance.
*Improved transient response
*Improved stability due to decreased sensitivity to modeling errors and disturbance
*Ability to eliminate steady state error

Question 7

What are some potential downsides to closed loop control over open loop control?

Answer 7

*Greater expense
*Greater complexity

Question 8

List the four standard control objectives

Answer 8

1) The closed loop system should be stable
2) The output should track the desired output response in the steady state.
3) The transient behavior should be satisfactory.
4) The control system should reject disturbances.

Question 9

A system of control that does not use feedback is know as what?

Answer 9

An open loop control algorithm

Question 10

Define control engineering

Answer 10

Control engineering is the science of changing the dynamic behavior of physical systems in some desirable way

Question 11

What is a control algorithm?

Answer 11

A mathematical equation which relates the input signal U to the desired output D.
Eg: Open loop proportional control algorithm:
U=Kp*D

Question 12

Define a System/plant/Process

Answer 12

An object of study consisting of a set of components which can be defined by its inputs and outputs.

Question 13

Define Control Input

Answer 13

A stimulus, excitation or command applied to a control system with the aim of producing a specific response.
Symbol U or Uk

Question 14

Define Set Point

Answer 14

Set point/Desired output response/Reference level/Command input is the required behavior of the system.
Symbol y, yd, D or r

Question 15

Define controller

Answer 15

An algorithm for automatically adjusting the control input to achieve control objectives.

Question 16

In a hierarchical objectives table how are the control objectives organised?

Answer 16

Into levels where the data flows from lower levels to the higher ones. This means that the set points of an objective may be influenced by a lower one.