Gps Base Accident Identification

Introduction
Example: model train controller.

Dept. of CSE&IT, DBCET, Guwahati

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Purposes of example
Follow a design through several levels of abstraction. Gain experience with UML.

Dept. of CSE&IT, DBCET, Guwahati

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Model train setup rcvr motor

power supply console

ECC

command

address

header
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Dept. of CSE&IT, DBCET, Guwahati

Requirements
Console can control 8 trains on 1 track. Throttle has at least 63 levels. Inertia control adjusts responsiveness with at least 8 levels. Emergency stop button. Error detection scheme on messages.
Dept. of CSE&IT, DBCET, Guwahati

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Requirements form

Dept. of CSE&IT, DBCET, Guwahati

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Digital Command Control
DCC created by model railroad hobbyists, picked up by industry. Defines way in which model trains, controllers communicate. Defines packet format and semantics

Dept. of CSE&IT, DBCET, Guwahati

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DCC electrical standard
Voltage moves around the power supply voltage 1 is 58 µs, 0 is at least 100 µs. logic 1 logic 0

time 58 µs >= 100 µs

Dept. of CSE&IT, DBCET, Guwahati

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Conceptual specification
Before we create a detailed specification, we will make an initial, simplified specification.
ִGives us practice in specification and UML. ִGood idea in general to identify potential problems before investing too much effort in detail.

Dept. of CSE&IT, DBCET, Guwahati

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Basic system commands command name set-speed set-inertia estop parameters speed (positive/negative) inertia-value (nonnegative) none
Dept. of CSE&IT, DBCET, Guwahati

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Message classes command set-speed value: integer

set-inertia value: unsignedinteger

estop

Dept. of CSE&IT, DBCET, Guwahati

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Subsystem collaboration diagram
Shows relationship between console and receiver (ignores role of track):
1..n: command :console :receiver

Dept. of CSE&IT, DBCET, Guwahati

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Typical control sequence
:console set-inertia set-speed set-speed