The Application Of Laser Self-mixing Sensor In The Fault Diagnosis Of Gear Box

Acceleration sensors are used to acquire the fault gearbox vibration signal. But the acceleration sensors adopt contact measurement modes so that the accuracy of results will be influenced. Therefore, self-mixing interference of laser sensor is used in this paper, and it successfully applied to the small planetary gearbox fault diagnosis. The sensor adopts non-contact measurement way, and no surface damage or measurement error will be brought up. The sensor also has many good property,such as high resolution, high EFT, small volume, low price, long service life, etc. It is a very ideal vibration sensor.In this paper, the main content divided into the following sections:(1) The generation of gear meshing vibration and the selection of vibration points are introduced, a vibration model of gear transmission system is established. Several common fault types and causes of planetary gear box are analyzed to build the fault signal model, and according to the characteristics of the fault signal model, several common fault signal characteristics of the waveform are listed.(2) Through the rational analysis of the self-mixing interference technology, the principle of self-mixing phenomenon is pointed out. According to the principle,several simulation on self-mixing waveform based on different parameters are made.(3) Several kinds of the self-mixing signal processing methods are expounded theoretically. And the feasibility of these methods is verified by experiments.(4) For small planetary gear box, two systemic failure analysis Researches have done.①Single channel fault diagnosis system is established. By combining the three aspects:time domain waveform characteristics, the gear box structure and the operation condition together, and compared the signal spectrum characteristics with theoretical models, the gear box fault type can be accurately diagnosed. ②dual channel fault diagnosis system is established, and under different rotational speed,the comparative analysis of time domain and frequency domain are made for trouble-free and fault gear box of dual channel waveform. In frequency domain analysis, two methods are adopted: the spectrum analysis and the cepstrum analysis. Through the experiments,these two analysis methods processed effect obviously. Meanwhile, it also proved the feasibility of self-mixing interference of laser sensor which can be used for gearbox fault diagnosis.