1. More kinds of FSM ENGR #

2. Menu More kinds of Finite State Machines Announcements:
Test next Wednesday

3. FSMs for generating behaviour
Controllers respond to sensors/signals with actions
Generators create behaviour
May be non-deterministic – multiple possibilities from a state
May have self transitions for staying in some state
Action 1
Action 8 A B
Action 2
Action 7
Action 3
Action 9
Action 4 C D
Action 5
Action 6

4. FSMs for generating behaviour
Controllers respond to sensors/signals with actions
Generators create behaviour
May have probabilities on transitions
May have self transitions for staying in some state
May also have other input conditions on transitions
Action 1
20%
80%
Action 8 A
10% B
80%
Action 2
50%
Action 7
50%
Action 3
10%
Action 9
Action 4
30%
30% C D
Action 5
40%
100%
Action 6

5. FSM for modeling and design
Designing smart homes for energy saving:
Want to turn devices on and off automatically to
minimise energy
maximise comfort.
Want to detect (and predict) behaviour of the occupants and respond differently in different states.
Did they leave the room/house for just a short time or will they be returning in 5 mins?
Did they leave the stovetop on for a reason? How much hot water will they use in the next 6 hours? ….
Need a model of what the occupants are likely to do, given as much information as you can detect from the house
Needs to be probabilistic

6. Modeling How much will it save to have a smart home?
Need to run a simulation and measure it.
Need a model of the occupants that will act like people in a simulated house.
Want to build a generative model of people's behaviour:
Cannot be deterministic – must account for variation.
Needs probabilities and statistical distributions
Building a NPC for a game:
character should have a variety of different behaviours
should respond to events by changing to different behaviours.
may want some unpredictability/independence/initiative
Eg, The Sims

7. Smart home occupant modeling
Need sensors, timings, and probabilities.
Need actions
Cleaning up
after mins
turn stove off
turn up main room heating
Eating dinner
in living room
Cooking
in kitchen
20%
Hot water in sink
Stove on
75% 5%
Arrive
Home
Watching TV
Doing Laundry
Unknown
Having
breakfast
at 5:30-6:00
if temp<18
turn on heating
Sleeping
Gone to
Work
50%
Having shower
50%
at 4am, turn on hot water
turn off heating

8. NPC design 98% Win fight enemy approaches On Guard Fighting 0.1% 1.9%
Losing fight
after 10 mins
Patrolling
Running
away
enemy approaches
after 8 hrs
Sleeping
Near a
hiding place
Hiding
after 20 mins 10

9. NPC design What is each state? Where are the actions?
FSM may be a high level design
Each state specifies a complete behaviour
set of rules for reacting
procedures/code to run
animation sequences …
FSM controls higher level of program
conditions for switching to different behaviour

10. FSM for Modeling speech.
Standard approach for speech recognition:
"Hidden Markov Models"
Just a FSM model of speech sounds.
sequence of frequency spectrums.
Each "phoneme" represented by a three state probabilistic FSM:
Each state specifies a probability distribution on the spectrum
98%
60%
70%
40%
30%

11. FSMs for Modeling Speech
Word is a sequence of phonemes
Can use as a generator, or
Match actual sound pattern to the predictions
Variety of techniques for automatically learning models from data. P A T
60%
70%
40%
30%
60%
70%
40%
30%
60%
70%
40%
30%

12. FSM Acceptors Acceptors:
FSM just has input: sequence of input words/symbols
Either accepts or rejects the sequence.
A “traditional” use of FSM's in computer science.
Describing little languages.
Searching for patterns in text.
"the"
"a"
"cat"
"rat"
"dog"
"and"
"ate"
"chased"
"cheese"
"barked"
"squeaked"

13. FSM Acceptors
Searching for patterns in text. eg, searching for recent dates:
"Regular Expressions" 9 9 8 8 7 7 6 6 5 5 4 4 3 3 3 2 2 2 1 1 1 1 / / 9 9 8 8 7 7 6 6 5 5 4 4 3 3 1 2 9 2 1 1 2 1

14. FSMs for language Lindsay eats breakfast (every day at 8am)
Lindsay was eating breakfast (yesterday at 7am)
Lindsay will have been eating breakfast (for three hours when the timer goes off)
Breakfast is being eaten (as we speak)
Breakfast should be eaten (before lunchtime)
Breakfast might be eating Lindsay! (if the grasshoppers haven’t been cooked properly)
+ tense
(past or
present)
Will
Did Do
Does
May
Might
Would
Should …
+ infinitive
“Have”
verb +
past-
participle
(…ed/en)
“Be”
verb +
present-
participle
(…ing)
“Be”
verb +
past-
participle
(…ed/en)
Main
verb

15. FSMs for Network Protocols
FSMs are often used to specify protocols.
Describes how each side responds to different messages
Used for
Understanding the protocol
Specifying and checking the protocol
Implementing the protocol.
Note additional structure in this FSM:
This is a FSM inside one state of a larger FSM!

16. FSMs for network protocols
DHCP protocol
(Dynamic Host
Configuration Protocol)
Finite State Machine describing the client side of the process
Diagram from:
(large site explaining networking
principles)