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Networks

Example: elevator controller.

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Terminology

Elevator car: holds passengers.

Hoistway: elevator shaft.

Car control panel: buttons in eachcar.

Floor control panel: elevator request,

etc. per oor.

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Elevator system

floor

floor

floor

floor

floor

Hoistway 1 Hoistway 2

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Theory of operation

Each oor has control panel, display.

Each car has control panel:

one button per oor!

emergency stop.

Controlled by a single controller.

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Elevator position sensing

coarse

sensor

fine

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Elevator control

Elevator control has up and down.

"o stop, disable both.

#aster controller: reads elevator positions!

reads requests!

schedules elevators! controls movement!

controls doors.

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Elevator system

requirements

name elevator systeminputs F oor control, $ position, $ car

control, % masteroutputs F displays, $ motor controllers

functions responds to requests, operatessafely

performance elevator control is time&critical

manufacturing cost electronics is small part of total

power electronics consumes small

fraction of totalphysical si'e(weight cabling is important

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Elevator system class

diagram

Car

Floor

Mastercontrolpanel!

Controller

Motor!

Coarsesensor!

Finesensor!

Carcontrolpanel!

Floorcontrolpanel!

1

1

1

"

1

F

1

1"

1

1

11

11

1

1

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Physical interfaces

#ensor!

hit$ %oolean

Coarsesensor! Finesensor!

Motor!

speed$ &o's'f(

Floorcontrolpanel!

up' down$ %oolean

Carcontrolpanel!

Floors)1**F+$ %oolean

emergencystop$

%ooleanopendoor' closedoor$

%oolean

Mastercontrolpanel***

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Car and Floor classes

Car

re,uestlights)1**F+$%oolean

currentfloor$ integer

Floor

uplight' downlight$

%oolean

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Controller class

Controller

carfloor)1**H+$ integer

emergencystop)1**H+$integer

scancars-.

scanfloors-.

scanmasterpanel-.operate-.

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Architecture

Computation and )(* occur at:

oor control panels(displays!

elevator cars! system controller.

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Panels and cab controller

+anels are straightforward&&&no real&time requirements.

Cab controller: read buttons and send events to system

controller!

read sensor inputs and send to systemcontroller.

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ystem controller

#ust tae inputs from many sources:

car controllers!

oors.

#ust control cars to hard real&timedeadlines.

-ser interface, scheduling are softdeadlines.

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Testing

uild an elevator simulator using anF+/0:

simulate multiple elevators! simulate real&time control demands.