Article

Research in Engineering Design

, Volume 1, Issue 3, pp 187-203

Representing imprecision in engineering design: Comparing fuzzy and probability calculus

  • Kristin L. WoodAffiliated withDepartment of Mechanical Engineering, University of Texas
  • , Erik K. AntonssonAffiliated withDivision of Engineering and Applied Science, 104–44, California Institute of Technology
  • , James L. BeckAffiliated withDivision of Engineering and Applied Science, 104–44, California Institute of Technology

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Abstract

A technique to perform design calculations on imprecise representations of parameters using the calculus of fuzzy sets has been previously developed [25]. An analogous approach to representing and manipulatinguncertainty in choosing among alternatives (design imprecision) using probability calculus is presented and compared with the fuzzy calculus technique. Examples using both approaches are presented, where the examples represent a progression from simple operations to more complex design equations. Results of the fuzzy sets and probability methods for the examples are shown graphically. We find that the fuzzy calculus is well suited to representing and manipulating the imprecision aspect of uncertainty in design, and that probability is best used to represent stochastic uncertainty.