Document Type

Article

Publication Date

8-1-2002

Publication Title

International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems

Abstract

Given a fuzzy logic system, how can we determine the membership functions that will result in the best performance? If we constrain the membership functions to a certain shape (e.g., triangles or trapezoids) then each membership function can be parameterized by a small number of variables and the membership optimization problem can be reduced to a parameter optimization problem. This is the approach that is typically taken, but it results in membership functions that are not (in general) sum normal. That is, the resulting membership function values do not add up to one at each point in the domain. This optimization approach is modified in this paper so that the resulting membership functions are sum normal. Sum normality is desirable not only for its intuitive appeal but also for computational reasons in the real time implementation of fuzzy logic systems. The sum normal constraint is applied in this paper to both gradient descent optimization and Kalman filter optimization of fuzzy membership functions. The methods are illustrated on a fuzzy automotive cruise controller.

Original Citation

Simon, D. (2002). Sum normal optimization of fuzzy membership functions. International Journal Of Uncertainty, Fuzziness & Knowledge-Based Systems, 10(4), 363-384.

Version

Postprint

Volume

10

Issue

4