A Comparison of Engineering Design Tools

Terry Bahill
Systems and Industrial Engineering
University of Arizona
Tucson, AZ 85721-0020, USA
terry@sie.arizona.edu
http://www.sie.arizona.edu/sysengr/methods.ppt
© 1998-2004 Bahill

Early in the design process, engineers must choose a method for designing the system. This choice is usually dictated by what methods the designer has previously used, not by an open selection process. In this paper we provide descriptions of some available design methods and examples of their use in order to help engineers select a design method. In this project we will develop benchmark problems that will be solved by a variety of design methods. We will identify characteristics of problems that might make one design method more or less appropriate. The top-level question we wish to answer is "For which type of problem is each method best?" If a system is to be actually built, then the system must ultimately be described as a collection of state machines. However, design engineers often stop short of producing these state machines. The design engineers use a method to create a high-level abstraction of the desired system. Then they turn this abstraction (or design) over to the specialty engineers who actually reduce it to state machines. In this paper, we present solutions for a simple design problem using the following 11 high-level system-design methods: State Transition Diagrams, Algorithmic State Machine Notation, Model-Based Systems Engineering, Graphical Description Language, RDD-100, Structured Analysis (using Entity Relationship Diagrams, Data Flow Diagrams, and State Transition Diagrams with Ward-Mellor notation), Functional Decomposition, Object-Oriented Analysis with Shlaer/Mellor Notation, Object-Oriented Analysis and Design with Booch Notation, an Operational Evaluation Modeling Directed Graph, and IDEF0. Each method was used by an expert user of that method. The solutions presented make it obvious that the choice of a design method greatly effects the resulting system design.

References: [69] and http://www.sie.arizona.edu/sysengr/methods/tools.html

This lecture is suitable for engineers. This talk requires an overhead projector or computer projection system. This talk takes one and a half hours.