Research On Fault Diagnosis Method Of Gearbox Based On FPGA

Gearbox,a kind of transmission device widely used in various mechanical equipments,plays an extremely important role in the fields of transportation,electricity,petrochemical and other fields.The normal operation of gears is a guarantee for the stable development of these industries.If gearbox failures are not dealt with in time,unpredictable losses would be caused in most cases.Therefore,the prevention and timely diagnosis of gear failures have practical significance.The key of fault diagnosis system is to acquisition information and extract fault feature.Hence,this paper designs a FPGA-based(Field Programmable Gate Array)fault acquisition system,which is modeled and simulated through fault classification.The correctness of the theoretical method is verified by case analysis.The main research contents of this thesis are as follows:1.By summarizing the development history of fault diagnosis,and analyzing the shortcomings of traditional vibration fault acquisition systems and methods,the design scheme of the gear fault collection system based on FPGA is proposed.2.The combination with the development trend of modern hardware devices leads to the design of FPGA-based gearbox data acquisition and signal pre-processing system.Then pre-processing those collected vibration signals with FIR and FFT on FPGA to achieve the preliminary denoising and time frequency transforrmation.3.Classify the gear fault as local gear faults and distributed faults according to their own characteristics,and establish corresponding models.Then simulate the broken teeth and eccentric faults with the MATLAB software,and extract and analyze effectively the signal characteristics by the analytical methods of time domain and the conbination of both respectively.4.The GDS(Gearbox Dynamics Simulator)would finish acquiring the vibration signals of normal gear and broken teeth.On one hand,through the methods of the time domain comparison,frequency domain component analysis,wavelet transform,and Hilbert transform,the feature of broken teeth faults can be extracted.It would be represented by a periodic impact signal in the real time domain,and an edge frequency band around the rotational frequency in the frequency domain that equals to the rotational frequency of the tooth mounting shaft.On the other,eccentric fault data could be analyzed as well.First of all,gather the modulated signals that reflect the off-center faults.Then,demodulate the eccentric fault frequency and its higher harmonics through the Hilbert transformation and the envelope spectrum to locate the the position of the eccentric fault.Thus,the correctness of the diagnostic method could be verified.The purpose of this thesis is to explore a method to quickly diagnose gear failures,optimizing both the acquisition platform and the diagnostic method.Through a large amount of experimental analysis,the correctness of the comprehensive diagnosis method therefore can be verified.Not only does it lay a foundation for the future transplantation of fault diagnosis method algorithms to the hardware,but also offers a new idea to the realization of a fast,high-precision portable gear fault diagnostic apparatus.