Design of a High-Speed Fuzzy Logic Controller Based on Log-Domain Arithmetic

One of the most important issues for a fast fuzzy-control system is to optimize the defuzzification module that involves computationally expensive multiplication and division operations. This paper introduces a log-domain approach that only requires addition/subtraction, max/min, and look-up table operations to implement a fuzzy controller. The control surfaces of the proposed system are compared to those of traditional fuzzy and PD controllers, and the results are almost the same when a small correction factor is included. For a second-order plant, the log-domain approach offers good step-response characteristics.