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© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Networks
Example: elevator controller.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Terminology
Elevator car: holds passengers.Hoistway: elevator shaft.Car control panel: buttons in each
car.Floor control panel: elevator request,
etc. per floor.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Elevator system
floor
floor
floor
floor
floor
Hoistway 1 Hoistway 2
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Theory of operation
Each floor has control panel, display.Each car has control panel:
one button per floor; emergency stop.
Controlled by a single controller.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Elevator position sensing
coarse
sensor
fine
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Elevator control
Elevator control has up and down. To stop, disable both.
Master controller: reads elevator positions; reads requests; schedules elevators; controls movement; controls doors.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Elevator system requirements
name elevator systeminputs F floor control, N position, N car
control, 1 masteroutputs F displays, N motor controllersfunctions responds to requests, operates
safelyperformance elevator control is time-criticalmanufacturing cost electronics is small part of totalpower electronics consumes small
fraction of totalphysical size/weight cabling is important
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Elevator system class diagram
Car
Floor
Master-control-panel*
Controller
Motor*
Coarse-sensor*
Fine-sensor*
Car-control-panel*
Floor-control-panel*
1
1
1
N
1
F
1
1
N
1
11
1
11
1
1
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Physical interfaces
Sensor*
hit: boolean
Coarse-sensor* Fine-sensor*
Motor*
speed: {o,s,f}
Floor-control-panel*
up, down: boolean
Car-control-panel*
Floors[1..F]: booleanemergency-stop:
booleanopen-door, close-door:
boolean
Master-control-panel...
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Car and Floor classes
Car
request-lights[1..F]:boolean
current-floor: integer
Floor
up-light, down-light:boolean
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Controller class
Controller
car-floor[1..H]: integeremergency-stop[1..H]:
integer
scan-cars()scan-floors()scan-master-panel()operate()
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Architecture
Computation and I/O occur at: floor control panels/displays; elevator cars; system controller.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Panels and cab controller
Panels are straightforward---no real-time requirements.
Cab controller: read buttons and send events to system
controller; read sensor inputs and send to system
controller.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
System controller
Must take inputs from many sources: car controllers; floors.
Must control cars to hard real-time deadlines.
User interface, scheduling are soft deadlines.
© 2008 Wayne WolfOverheads for Computers as
Components 2nd ed.
Testing
Build an elevator simulator using an FPGA: simulate multiple elevators; simulate real-time control demands.
