Compound-Fault Diagnosis of rolling bearing based on Order Wavelet Packet and Rough Sets Theory
Hai-Ying Kang, Yan‐Jie Qi, Guangsheng Liu, Ren-fa Shen · 2015
The diagnosis of compound-fault is always a difficult point, and there is not an effective method in equipment diagnosis field, and then a new method of compound-fault diagnosis was presented in the paper.The vibration signals at start-up in the gearbox are non-stationary signals, in order to solve the compound-fault diagnosis of rolling bearing, the order tracking wavelet packet and rough sets theory are combined and introduced into the fault diagnosis field.Firstly, the non-stationary vibration signals at start-up were resampled using computer order tracking arithmetic and equal angle distributed vibration signals were obtained, and then the signals were decomposed and recomposed with the wavelet packet.The energy distribution of every frequency band was calculated according to normalization process.A new feature vector can be obtained, then clear and concise decision rules can be obtained by rough sets theory.Finally, the result of compound-fault example proves that the proposed method has high validity and more amplitude appliance foreground. ⅠIntroductionThe rolling bearing is one kind of equipment, which is extensive in existence range, most amount and applied in most universal in many machine.When there are fault in rolling bearing, the natural frequency of bearing vibration system will be activated by high-frequency vibration, which is generated by local scathing component of rolling bearing at work [1].It is very useful and necessary for researching the compound-fault of rolling bearing.The vibration signals of rolling bearing are non-stationary signals and it is consisted of cluster harmonic components of fault character frequency.There are quadratic phase angle couple in local dandify vibration signals of rolling bearing.The fault vibration signals of rolling bearing is non-stationary and non-gauss distribution signals [2].Under this condition, the request of stationary about signals can't be suited to FFT.In order to solve the problem, the theory of angle sample and theory of order tracking analysis, which based on the theory of angle sample, are generated.Compared with the normal signals, the energy of some frequency band lies more difference, it is may monish or accretion.So, the energy of the frequency band signals is included abundant fault information [4].The wavelet analysis is one advanced measure of time-frequency analysis.The fault character of impulsion signals in vibration signals can be effectual distilled.It is one availability method for rotate machine fault character distilling.The rough set theory is one new mathematics tool which is disposed with the fussing mathematics and indetermination problem.When the information is disposed, the data is reduced and the least expression of intellective is obtained on the precondition of the key information is no dignify.The minimal rule is obtained.The aptitude fault diagnosis method based on rough set theory is the method based on information.This is the most excellence which is compare with the fuzzing theory and evidence theory [3].So, it is very important that the rough set method of equipment fault diagnosis is developed.In the field of equipment fault diagnosis, the diagnosis of compound-fault is always the difficulty [4].The order wavelet change is adopted as the disposal tool of signals in the paper.The vibration signals during the course of start-up in gearbox is analyzed with order tracking, the signals after