Analysis on comparison of Permutation Entropy with Correlation Dimension for abnormality detection of a rolling bearing

Permutation entropy and fractal theory are new methods which are used to study irregularity and nonlinearity of a complex system in nature. Principle of Permutation Entropy (PE) and Correlation Dimension (CD) is introduced in this paper firstly, their differences in describing the complexity of vibration signal were analyzed and the selection methods of algorithm parameters were put forward, then taking the whole life vibration data of a bearing as an example, PE and CD algorithm were applied to detect abnormal characteristics respectively, and their difference on abnormal detection are compared with each other. It is concluded that the result of two detection methods is basically coincident, but PE has advantages in computational efficiency, which is much more suitable for online monitoring and will play an important role in preventive maintenance of mechanical equipments.