New Systems Engineering Tools Based on
The Unified Modeling Language (UML)

Terry Bahill
Systems and Industrial Engineering
University of Arizona
Tucson, AZ 85721-0020
terry@sie.arizona.edu
http://www.sie.arizona.edu/sysengr/slides/HVAC.ppt
Copyright © 2002-2004 Bahill

20th century systems were primarily mechanical hardware systems. 21st century systems will be primarily electronic software systems. In moving from the 20th to the 21st century, systems engineering tools evolved. It would be nice if these new tools were used by both systems and software engineers. It would be nice if systems and software engineers spoke the same language.

To design systems we use requirements, specifications, block diagrams, scenarios, timelines, functional decomposition, functional flow block diagrams, enhanced functional flow block diagrams, data flow diagrams, finite state machines, verification matrices, etc. However, there is no standard usage; different people use each tool differently and these tools do not work together. The software folks have taken these tools, improved them and made them interact. Then, they created a standard for using these tools, a standard that most universities are teaching and hundreds of companies are using. This standard is called the Unified Modeling Language (UML). The UML defines a set of tools designed to help communicate engineering concepts.

The UML supports about nine types of diagrams. There are two important reasons why so many diagrams are used. First, a system cannot be described with only one diagram: many aspects are necessary. Second, much of the information in a UML model appears in several diagrams. This produces double checking and incremental growth of the models. However, with modern implementations, if you change an item, you only have to change it in one place and the change automatically propagates throughout all the diagrams.

The Unified Systems Engineering Process has five major themes: (1) requirements (get them early and get them right, but plan for change), (2) architecture (design the interfaces early), (3) reuse components and models, (4) plan frequent small iterations, and (5) manage risk (start risk analysis early and develop high-risk subsystems first).

Lockheed Martin won the Joint Strike Fighter competition partially because of their superior object-oriented and UML models. The use of object-oriented and UML tools for system and hardware design was a "major strength" in Raytheon's winning proposal for the DD(X), because it had systems and software engineers talking the same language.

Reference: [81]. This overview was designed for hardware and algorithm design engineers. This talk requires CD ROM drive, PowerPoint and a computer projector. This talk takes an hour and a half.