*2.5.3 Influence and relationship between rolling bearing motion and chaos*

Rolling bearing is similar to chaotic water wheel device. The fault location will affect the rotation of rolling bearing, and the rotation will be chaotic. The direction and speed of rotation will have complex but regular motion characteristics due to the inherent nonlinearity of the system. Because of the different fault locations, the vibration signals presented by the rolling bearing rotation are different.

#### *2.5.4 Entropy and chaos phenomenon*

Entropy is a measure of disorder, in a chaotic system. The greater the entropy, the more chaotic the chaotic system is. The smaller the entropy, the more orderly the chaotic system is. Approximation entropy, sample entropy, and information entropy are all entropy, and as characteristics, they also affect the chaotic degree of chaotic phenomena.

### **2.6 Summary**

The basic structure of the rolling bearing and the relevant parameters are introduced briefly. Six common rolling bearing failures are subsequently described. The cause of bearing vibration is clearly explained and the method of the characteristic frequency of inner ring, outer ring, and rolling body is given. We briefly introduce the western storage university bearing fault diagnosis equipment and state the data used in this paper.
