Multi-Class Classification of Fatigued Banknotes by using Frequency Spectral Difference

The vending machines with a banknote handling device are widely used in Japan. The fatigued banknotes is the main reason of paper jam problems in these machines. Therefore we propose a method to solve this problem by extracting the features of fatigued bills that is not depend greatly on the classifier. The method is to detect the feature quantity of the frequency difference from acoustic signals of banknotes. This feature quantity is possible to cope with time-series change of the acoustic signal by the fatigued degree of banknotes. And the discrimination experiments of fatigued banknotes were performed by Dynamic Time Warping (DTW) with the frequency difference as input. The results showed that this feature quantity is effective to classify the fatigued banknotes.