Homework #1 – ENPM 641

Purpose

Learn systems level modeling using UML.

Introduction

The following UML representation has been compiled for ENPM 641, homework problem #1.

The problem addresses the design characterization of a human-powered surface transportation vehicle

suitable for a 3 year-old (i.e. a tricycle).

System Boundaries

The system boundaries in this case include all associated parts of the tricycle. This includes the

cycle frame w/rear step, wheels, pedals, seat, fork and handlebars. The following diagrams illustrate the hierarchical design and flow of activities for the use of the tricycle. The UML methods used were the Class

Diagram and Activity Diagram respectively.

Class Diagram

Activity Diagram

Actors

1) 3 year-old

2) Parent

3) Environment

Use Cases

Scenario 1 - Sitting:

· Actors: 3 year-old

· Description: The 3 year-old decides to sit down on the tricycle.

· Normal Behavior: In the normal state, the seat will support the 3 year old in the sitting position.

· Abnormal Behavior: In the abnormal state, the seat will not support the 3 year old and repairs are necessary.

Scenario 2 - Standing:

· Actors: 3 year-old

· Description: The 3 year-old decides to stand up on the tricycle.

· Normal Behavior: In the normal state, the rear step will support the 3 year old in the standing position.

· Abnormal Behavior: In the abnormal state, the rear step will not support the 3 year-old and repairs are necessary.

Scenario 3 – Moving Seated:

· Actors: 3 year-old

· Description: The 3 year-old, seated on the tricycle, pedals forward or backward.

· Normal Behavior: In the normal state, the tricycle will move forward or backward.

· Abnormal Behavior: In the abnormal state, the tricycle will not move indicating the tricycle needs repair or is stuck.

Scenario 4 – Moving Standing:

· Actors: 3 year old

· Description: The 3 year old, standing on the tricycle’s rear step, thrusts the tricycle forward.

· Normal Behavior: In the normal state, the tricycle and 3 year-old will move forward.

· Abnormal Behavior: In the abnormal state, the tricycle will not move indicating the tricycle needs repair or is stuck.

Scenario 5 – Steering:

· Actors: 3 year old

· Description: The 3 year old, while moving on the tricycle, turns the handlebars left or right.

· Normal Behavior: In the normal state, the tricycle and 3 year-old will move left or right.

· Abnormal Behavior: In the abnormal state, the tricycle will not steer, indicating the tricycle needs repair.

Scenario 6 – Crash:

· Actors: 3 year old, Parent

· Description: The 3 year old, while moving on the tricycle, turns the handlebars left or right and crashes the tricycle.

· Normal Behavior: In the normal state, the tricycle and 3 year-old will move left or right, topple over and crying will ensue. The parent will rush over, right the tricycle and 3 year-old and kiss the boo-boo.

· Abnormal Behavior: In the abnormal state, the tricycle will seemingly contain an advanced gyroscope, and never topple over.

Scenario 7 – Environmental Interaction:

· Actors: 3 year old, Environment

· Description: The tricycle is designed for use on a solid engineered surface such as concrete, asphalt, or an interior floor.

· Normal Behavior: In the normal state, the tricycle will move when either pedaled or thrust forward.

· Abnormal Behavior: In the abnormal state, the tricycle will not move because it is stuck in gravel, grass, or dirt.

Conclusion

The use cases presented cover important aspects of the operation of the human-powered surface

transportation vehicle suitable for a 3 year-old (i.e. a tricycle).