Increasing the Accuracy of Fuzzy Neural Networks by Optimizing Membership Functions
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Abstract
The article is devoted to solving the urgent scientific and practical problem of increasing the accuracy and stability of modeling of intelligent systems based on hybrid fuzzy neural networks. The need to optimize the fuzzification parameters is due to the high sensitivity of fuzzy models to the geometric shape and localization of membership functions. The paper provides a detailed comparative analysis of the influence of membership function types (Gaussian, bell-shaped, triangular and trapezoidal), standard learning methods (hybrid algorithm, backpropagation error method) and modern population algorithms of global optimization (genetic algorithm and swarm intelligence method) on the approximation and predictive properties of a fuzzy network of the ANFIS class and a modified five-layer FNN structure. The efficiency of the studied configurations was assessed using statistical metrics of the mean square error and the coefficient of determination, as well as indicators of computational complexity and the result stability assessment. Experimental testing was performed on two different types of tasks: forecasting a complex chaotic Mackay-Glass time series and regression analysis of a real multidimensional Auto MPG dataset from the UCI Machine Learning Repository. The results obtained proved that for smooth processes without significant noise, the optimal configuration is a configuration with a Gaussian membership function and a hybrid learning method. At the same time, for real datasets, the classical hybrid method turns out to be ineffective due to falling into local minima, while the use of a genetic algorithm and swarm intelligence in combination with the Adam optimizer allows achieving stable accuracy, fast and stable convergence and significantly enhance the reliability of fuzzy neural networks functioning.
