基于二階線性系統(tǒng)與非線性系統(tǒng)的微弱信號(hào)檢測(cè)研究
[Abstract]:In modern production, real-time monitoring and fault diagnosis of important key equipment is of great significance. However, in the early fault of many equipment, the fault signal is often submerged by noise and difficult to detect, so the detection of weak signal is especially important, and more attention has been paid to it. Based on the second-order linear system as the signal detection processing model, a weak signal processing method based on the parameter-adjusted resonance of the second-order linear dynamic system is proposed. The basic principle is that the signal to be detected including the characteristic frequency component and noise interference is regarded as the excitation of the system, while the linear dynamic system is regarded as the signal processing model. By artificially adjusting the natural frequency and damping ratio of the system, the natural frequency is equal to the characteristic frequency of the signal to be detected, so that the response of the system reaches resonance, and then the characteristic signal is further prominent and the noise is overcome. To achieve the purpose of detecting the components of the characteristic signal. The concrete implementation of this method is that the characteristic signal in the noise can be identified according to the maximum value in the curve after the characteristic curve of the maximum value of the system response varying with the natural frequency is obtained. This kind of signal detection based on linear system model can optimize the detection result by selecting the appropriate damping ratio parameters of the system. Secondly, taking the typical Duffing system as the object, the information detection method based on stochastic resonance of second-order nonlinear system is studied. By means of the nonlinear bistable system, the weak signal to be measured and the noise superimposed in the signal are matched optimally, so that the noise energy is transferred to the signal and the weak signal energy is enhanced, thus the weak fault signal is extracted. For the small parameter signal which satisfies the adiabatic approximation theory, the bistable system stochastic resonance can be directly used to detect the signal. For large-parameter signals, the variable-scale stochastic resonance method can be used to transform the large-frequency signals into small-parameter signals which satisfy the adiabatic approximation theory by linearly compressing the frequency of large-frequency signals. So the random resonance detection of large parameter signal can be realized. The adjustment of duffing system parameters can make the system and signal best match with large noise, and improve the effect of random resonance detection. Finally, the signal detection method based on the second-order linear system and the nonlinear Duffing system is applied to the fault diagnosis of the rotor system respectively. The two methods are compared and analyzed, and the results show that the sampling points are less and the noise is lower for the two methods. The detection method based on linear system is better than the stochastic resonance detection of nonlinear Duffing system for the fault signal with large amplitude and frequency interference.
【學(xué)位授予單位】:天津大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2012
【分類號(hào)】:TH165.3
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