Car System

Car System Case Study PDF (2002)

1. The car can only be started if it is in the PARK state when the driver inserts the key in the ignition and turns it on. A dashboard light remains on if the driver's seat-belt is not fastened when the driver is seated and the ignition is on. If the hand-brake is on when the ignition is on, the brake-light turns on. The security alarm is on when the car is locked and if anyone tries to break in by breaking a window or forcing a door the alarm will sound. When the driver, on approaching the car, presses the key-button it unlocks the door and turns the security alarm off.

2. When the car is unlocked the driver may get in and put the car into the park state.

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Security Alarm

Security Alarm System Case Study PDF (2006)

1. The security alarm has a detector that sends a trip signal when motion is detected. The security alarm is activated by pressing the Set button. The set button is illuminated when the security alarm is set. If a trip signal occurs while the security alarm is set, a high-pitched tone (alarm) is emitted. A three-digit code must be entered to turn off the alarm tone. Correct entry of the code deactivates the security alarm.

2. If a mistake is made when entering the code, the user must press the Clear button before the code can be re-entered.

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Minepump

The requirement is to design a simple pump control system to prevent flooding in a mineshaft. Water collects in a pump at the bottom of a mineshaft. When it reaches a certain depth (detected by a high-water sensor) the pump should be switched on. When the depth has been sufficiently reduced (detected by a low-water sensor) the pump should be switched off. The pump can also be switched on or off at the request of a human operator, provided the water level is between its high and low limits. A designated operator, the supervisor, has authority to switch the pump on or off whatever the water level.

Risk of fire dictates that pump must not be operated when the atmosphere contains too much methane. The methane level is measured by a methane sensor: two other sensors, a carbon monoxide sensor and an airflow sensor also monitor the environment. A critically high carbon monoxide level or a critically low airflow lead to immediate evacuation of the shaft. A critical reading from any of the sensors causes an alarm to be sent to the human operator. All readings whether critical or not, are logged for possible future analysis, as are records of the pump's activities.

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Others

Train Station Case Study (May 2004)
The Train Station case study is used as the first translation exercise to introduce people to the process of translating functional requirements into Behavior Trees. Composition Tree.

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