OSM for a fob watch

This description uses OSM version 2 (for full paper, see Blandford and Green 1998)

 date: Feb 98

a) The shared description

entities:

entity
type
add by
delete by
attribute
set by
change by
notes
GMT/'real' time
user private
-
-
current time
-
-
externally defined
time shown
shared/domain
-
-
minutes angle
-
turn knob (when out)

 

hours angle
-
change minutes angle

 

energy
device private
-
-
amount
-
decreases as watch runs; increase by winding knob

relationships:

domain constraint:

time shown should be same as GMT

affects:

changing the minutes angle affects hours angle

device constraint:

watch can only work if it has enough energy; only a finite amount of energy can be stored

b) Adding domain knowledge

How users use the device: Fob watches are mainly used for telling the time of day, of course. They are also used to work out elapsed time (how long has this process been going on?), time-remaining (how much longer will it go on?), time-of-completion (what will the time be when this process has continued for X minutes?), and current time in other time zones.

Domain concepts and relationships: From the above, three domain concepts need to be introduced, time-elapsed, time-remaining, and time-of-completion.

Context of usage, and related tools or devices: Because the fob watch has no alarm system, it is frequently used in conjunction with separate devices for countdown timing (e.g. egg-timers) and for reminders at set times (e.g. alarm clocks). Transferring data from one of these to another may require translation between digital and analogue time representations.

c) Expanding the device description

conceptual action
device actions
device object
persistence
disguised?
notes
turn knob (when out)
pull knob out, turn it, press it back in
knob
high
no
moded: knob must be out to change time
wind knob
turn knob
knob
high
no
moded
find elapsed time
read current time and subtract a previous time (possibly recorded on a sub-device such as paper; possibly from memory)
hands (and possibly paper)
high
no
subtraction of times is a reasonably hard mental operation

d) Misfits etc

 

Illustration

 

diagram of fob watch

the long arrow is the minute hand 

the short arrow is the hour hand 

the black bit on top is the knob 

turn the knob to wind the watch: winder mode 

pull the knob out to turn the hands 

 

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last updated: Feb 99