Lecture 1 - Introduction to Control

Question 1

vestibulo-ocular reflex (VOR)

Answer 1

eye movement reflex that stabilizes imagines on the retina during head movement

Question 2

control theory + genetics =

Answer 2

systems biology

Question 3

control theory has been applied to which fields?

Answer 3

• motor physiology - gene regulatory networks

Question 4

define: plant

Answer 4

thing we want to control/influence

Question 5

___ receives input and sense commands to the plant

Answer 5

controller

Question 6

types of control

Answer 6

1. open loop 2. feedback 3. internal feedback

Question 7

open loop

Answer 7

input -> controller -> plant -> outcome

• controller receives no feedback

Question 8

Another name for open-loop

Answer 8

ballistic control

Question 9

Limitation of open-loop control

Answer 9

cannot recover from malfunctions or disturbances happening at the plant

Question 10

Feedback control

Answer 10

Control system which monitors its own progress and adjusts its commands accordingly

Question 11

Examples of feedback control:

1. Mechanical
2. Biological

Answer 11

1. Heat seeking missile
2. balance

Question 12

What body parts do we use for balance/posture?

Answer 12

• Inner ears
• Vision

Question 13

Limitation of feedback control

Answer 13

• disturbance is too great
• Delay around the loop

Question 14

In feedback control, ____ send information about outcomes back to controller.

Answer 14

Sensors

Question 15

Solution to feedback delay

Answer 15

Use plant models and internal feedback

Question 16

define: plant model

Answer 16

• Mimic the actions of the plant (what the plant is doing or what it is about to do)
• Send info to controller with little delay (located close to controller)

Question 17

Disadvantage of plant model

Answer 17

If the model is inaccurate or ignores some disturbances in the real plant, the system malfunctions

Question 18

Information about how to move your eyes come from _____ when head is moving.

Answer 18

Inner ear

Question 19

____ measures head rotation and is responsible for VOR

Answer 19

inner ears

Question 20

VOR’s plant is…

Answer 20

the eyeballs

Question 21

VOR’s input comes from…

Answer 21

semicircular canals of the inner ear (there are 3 canals – x, y and z axis plane)

• each canal is responsible for firing afferent nerve fibres at a rate proportinal to the rotary head velocity in the plane of that canal

Question 22

The semicircular canals sense… (VOR)

Answer 22

rotary head velocity

Question 23

The semicircular canals are called _____ organs because they lin within a chamber called the _____ in the inner ear

Answer 23

• vestibular organs
• vestibulum

Question 24

Why is the VOR called VOR?

Answer 24

it uses information from vestibular sensors to control the eyes

Question 25

Pathway for VOR control

Answer 25

1. Semicircular canals
2. Primary vestibular neurons (in vestibular gangion)
3. Secondary vestibular neuronsneurons (in vestibular nucleus)
4. Motoneurons (in cranial nerve nuclei 3, 4, 6)
5. Eye muscles

Question 26

How many cranial nerves do we have on each side of the brain?

Answer 26

12

Question 27

Which cranial nerves do the VOR involve?

Answer 27

3, 4, 6

Question 28

Streptomycin is a…

Answer 28

antibiotic

Question 29

VOR is ____ control. Why?

Answer 29

open-loop

head velocity→controller→eyes→eye position

Since the inner ear regulates VOR, it can’t “see” if the images are actually stable on the retina

Question 30

VOR: eye velocity should =

Answer 30

• head velocity

Question 31

Plant equation (gives eye velocity)

Answer 31

dx/dt = (u - kx) / p

• v = head velocity
• u = controller / command
• x = eye position
• k, p = constant (mechanical properties of the eye muscles)

Question 32

What part of the plant equation does the controller alter? What does it want it to equal?

Answer 32

• Alters u
• dx/dt = -v

Question 33

The controller’s law is called…

Answer 33

control law

Question 34

Control Law

Answer 34

u = kx - pv

• Brain sends this command to the eye muscles to keep retinal images stable

Question 35

control law keeps head velocity = -eye velocity provided that…

Answer 35

k and p (constants) used by the controller and the plant are the same

Question 36

What happens if the controller’s p’ value is 80% of the plant’s p value? (p’ = 0.8p)

Answer 36

eye velocity is 80% as large as head velocity (dx/dt = 0.8v)

• On the graph, amplitude changes

Question 37

What happens if the controller’s k’ value is 50% of the plant’s k value? (k’ = 0.5k)

Answer 37

eye velocity is out of phase with head velocity

• On the graph, displacement in the x direction changes

Question 38

In general, a control system only funtions properly if…

Answer 38

Its controller is tuned to its plant

• k’ = k
• p’ = p

Question 39

VOR’s controller involves several brain structures, but its core is _______

Answer 39

brainstem neurons