Profiles of typical users

Anna is an 81-year-old lady living in a care house. She has some trouble walking, but she is very interested in current news from all around the world. She spends most of her time reading newspapers and watching news on TV.

She is not very interested in technology, but she has learned how to use simple devices like a TV remote and a microwave oven.

Pekka is a 67-year-old man, also living in a care house. He has poor eyesight, even with glasses on he can not read text in normal newspapers, only the headings. His hands are shaking, making it impossible for him to hold things steadily or perform complicated gestures.

He is fascinated with technology; he has a mobile phone (with a large display and buttons). Sometimes his grandson visits him and shows him a laptop computer; but Pekka can't use it because the buttons and text are too small.

Technology notes for a multi-touch device.

Screen Resolution

iPhone 320x480

new iPod 640x480

Wacom Cintiq 12WX 1600x1200

Touch resolution

Can be smaller than screen resolution

Newspaper-like UI

Magazines 133-150 lpi 200 dpi

Newspapers 85 lpi 150-200 dpi

High-quality book 200 lpi

Programming interfaces

Multitouch for Java

Qt 4.6 (Low-level and/or gesture events; not mature; LGPL)

Operating System support

Windows CE

Embedded Linux

Qt Embedded

Common technologies

E-paper (low resolution & refresh rate, no backlight needed)

OLED (expensive)

LCD (backlight needed)

Gesture support/pressure-sensing

Gesture support: need 2 points of contact

Pressure sensing: not needed

Overall suggestion of technology

LCD, capacitive touchscreen, Qt Embedded for software

Use cases

Select transaction type

Use case ID: 1

Description

The user selects the duration of the parking time and the method of payment

Actors

User

Assumptions and constrains

Pre-condition: The machine is not disabled

Post-condition: The user has selected the duration and method of payment

Steps to achieve the goal

1. The user selects the duration (see use case 2)

2.

The user selects the method of payment (see use case 3)

Related non-functional requirements

The system shall correctly respond to a button press within 0.25s

Error cases

a. Selecting the duration or method of payment is aborted

1. The system shows the welcome message

2. The use case is repeated

__________________________________________

Select parking duration

Use case ID: 2

Description

The user selects the duration of the parking time

Actors

User

Assumptions and constrains

Pre-condition: The machine is not disabled

Post-condition: The user has selected the duration

Steps to achieve the goal

1. User presses the GET TICKET button

2. The system shows a list of duration options: ½, 1, 2, and 4 hours

3. User presses a button corresponding to one of the options

Related non-functional requirements

The system shall correctly respond to a button press within 0.25s

Error cases

a. There is not enough free parking places after User presses the GET TICKET button

1. The system shows the message “No parking spaces left”

2. The use case is aborted.

b. There has been more than 30 seconds without user's activity

2. The use case is aborted.

__________________________________________

Select payment method

Use case ID: 3

Description

The user selects the payment method

Actors

User

Assumptions and constrains

Pre-condition: The user has selected the duration

Post-condition: The user has selected the Credit card payment method

Steps to achieve the goal

1. The system shows a list of payment options: “Credit card” and “Phone”

2. User presses a button corresponding to one of the options

Related non-functional requirements

The system shall correctly respond to a button press within 0.25s

Error cases

a. User selects a button that does not correspond to one of the choices on the list

1. The system shows the message “Invalid choice, please try again”

2. Go back to step 1 of the use case.

b. There has been more than 30 seconds without user's activity

2. The use case is aborted.

__________________________________________

Select payment by phone

Use case ID: 4

Extends Use Case 3

Description

The user selects the Phone payment method

Actors

User

Steps to achieve the goal

1-2 same as in Use Case 3

3. The system displays its phone number and phone-payment instructions.

Related non-functional requirements

The system shall correctly respond to a button press within 0.25s