On-line control of nonlinear systems using a novel type-2 fuzzy logic method

Abstract

In this paper, a new type-2 fuzzy logic controller (T2FLC) is proposed for on-line control of nonlinear systems. The proposedmethod provides more flexibility in applying human thinking in control system design in comparison with the traditional or eventype-1 fuzzy logic controllers. One encounters some problems using the type-2 fuzzy logic controllers on-line because of thelarge volume of computations required. The main aim of this paper is to propose a new type-2 fuzzy controller with a smallcomputational burden so that it can be used on-line. In the proposed T2FLC, the programs related to the computation of unionof all qualified consequent T2MFs are divided into some sub-problems, and to design the T2FLC - not interval -we merge theType Reducer and Defuzzifier into one step. By doing so, the computational time reduces, and the performance of our T2FLCincreases so that it can be used on-line in dynamic systems. We study the noise concealing properties of the proposed T2FLCas well. The proposed method is applied to two non-linear dynamic systems, ball & beam and inverted pendulum. The resultsare compared with PID and type-1 fuzzy logic controllers. In the simulation results, it is also shown that the proposed controllerhas good noise cancelling properties.