Week 4

Question 1

what is a continuous time signal?

Answer 1

Represented by a continuous function of time u(t), y (t), x (t)

Question 2

what is a Discrete-time signal?

Answer 2

Represented by a sequence of numbers
u1, u2, . . ., y1, y2, . . . (with a constant separation in time, fixed period)

Question 3

what is an event?

Answer 3

Represented by a sequence of (finite) numbers occuring at some moments in time (no fixed period)

Question 4

what is a state?

Answer 4

one or more variables (including output signals?)
x (t), xk

Question 5

what is a state transition law?

Answer 5

how state changes over time

Question 6

what is an output function?

Answer 6

How the output of the system depends on the state

Question 7

what is control theory?

Answer 7

the branch of engineering which deals with the identification or modeling of systems and the design of methods to control their outputs.

Question 8

what is a plant?

Answer 8

The given system we want to control

Question 9

what is a setpoint?

Answer 9

The signal we want the system’s output to be

Question 10

what is a controller?

Answer 10

The system (sometimes just a function, i.e. no state) we design to control the plant

Question 11

what is an error?

Answer 11

The difference between the setpoint and the output of the plant i.e. what we want the plant to do vs. what it is really doing

Question 12

what is the stability of a system?

Answer 12

Has many different definitions. BIBO stability (Bounded Input Bounded Output) is widely used: If the input of the system stays within some bounds the output will also be bounded (i.e. nothing blows up)

Question 13

what is perturbation?

Answer 13

A signal, we cannot control, that affects the output of the plant

Question 14

what is a transient?

Answer 14

The period of time from setting the setpoint until the system does what we actually requested (Nothing changes instantaniuosly)

Question 15

what is a steady state?

Answer 15

Period of time we consider the system is behaving as we wanted (after settling time).

Question 16

what are examples of control systems?

Answer 16

-elevator
-driving

Question 17

what is a block diagram?

Answer 17

A graphical way of representing the connections/relations between sub-systems in control theory

Question 18

what 2 sides does a DC motor have?

Answer 18

-electrical
-mechanical

Question 19

what is the electrical side of a DC motor?

Answer 19

When you plug a battery to the motor

Question 20

what is the mechanical side of a DC motor?

Answer 20

The acceleration of the motor axis

Question 21

what is an open loop control?

Answer 21

a type of continuous control system in which the output has no influence or effect on the control action of the input signal

Question 22

what is a feedback control?

Answer 22

A feedback controller measures the output of a process and then manipulates the input as needed to drive the process variable toward the desired setpoint.

Question 23

what is a cascade control?

Answer 23

Cascade control involves the use of two controllers with the output of the first controller providing the set point for the second controller, the feedback loop for one controller nestling inside the other

Question 24

what is a proportional controller?

Answer 24

a control system technology based on a response in proportion to the difference between what is set as a desired process variable (or set point) and the current value of the variable.