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Diesel Engine High Frequency Pressure Oscillation Signal Extraction Method Based on Improved Wavelet Packet Transform

A technology of wavelet packet transformation and oscillation signal, which is applied in the field of high-frequency pressure oscillation signal extraction of diesel engines, can solve the problems of frequency confusion and unsatisfactory frequency-domain cut-off characteristics of wavelet filter banks, and reduce frequency confusion and amplitude distortion. Guaranteed convergence and accuracy, and the effect of reducing the amount of calculation

Active Publication Date: 2021-11-23
HARBIN ENG UNIV
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Problems solved by technology

However, the traditional intelligent algorithm will have the problem of local convergence, so that the frequency-domain cut-off characteristics of the constructed wavelet filter bank are still not ideal, and there are still serious frequency confusions in the wavelet transform.

Method used

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  • Diesel Engine High Frequency Pressure Oscillation Signal Extraction Method Based on Improved Wavelet Packet Transform
  • Diesel Engine High Frequency Pressure Oscillation Signal Extraction Method Based on Improved Wavelet Packet Transform
  • Diesel Engine High Frequency Pressure Oscillation Signal Extraction Method Based on Improved Wavelet Packet Transform

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Embodiment Construction

[0022] The following examples describe the present invention in more detail.

[0023] Overall block diagram of the present invention is as attached figure 1 shown, with figure 1 The specific steps are as follows:

[0024] Step 1: Normalize the wavelet filter coefficients. define h k is the coefficient of the wavelet low-pass filter, since the sequence {h k} needs to meet many constraints, and its construction must be very complicated. And a sequence of length N {h k} can use a sequence of length N / 2-1 {θ k} to express:

[0025]

[0026] In the formula

[0027] E(z)=V N′-1 (z)V N′-2 (z)···V 1 (z)V 0 (z) (2)

[0028]

[0029]

[0030]

[0031]

[0032] In the formula N'=N / 2, z means e jω , H(z), G(z) are the Fourier transform of low-pass and high-pass wavelet filter coefficients respectively. For the sequence {θ k} initialization, so that it can be used for optimization in the following steps.

[0033] Step 2: Optimizing the normalized wavelet f...

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Abstract

The invention provides a method for extracting high frequency pressure oscillation signal of diesel engine based on improved wavelet packet transformation. 1: Normalize the wavelet filter coefficients; 2: After normalizing the wavelet filter coefficients, use the normalized filter coefficients as individuals in the chicken flock to realize the initialization of the chicken flock algorithm. After constructing the cost function, use The chicken group algorithm optimizes the wavelet filter according to the individual fitness; 3: The filter bank obtained in step 2 is used as the initial value of the sequence quadratic programming method to perform the second iterative optimization, and the cost function is consistent with the step; 4: Using the wavelet filter bank constructed in steps 2 and 3, the three-layer wavelet packet transform is performed on the diesel engine cylinder pressure signal to extract the high-frequency pressure oscillation signal. Compared with the existing wavelet improvement method, the calculation amount of the invention is greatly reduced; the wavelet filter bank whose frequency domain characteristic is very close to the ideal cut-off can be constructed, and the frequency confusion and amplitude distortion phenomena in the wavelet packet transformation process are greatly reduced.

Description

technical field [0001] The invention relates to a method mainly used for extracting high-frequency pressure oscillation signals of diesel engines. Background technique [0002] By extracting and analyzing the high-frequency pressure oscillation signal of the diesel engine, the condition monitoring and combustion noise estimation of the diesel engine can be realized. The high-frequency pressure oscillation signal exists in the cylinder pressure signal, so in order to extract the characteristics of the high-frequency pressure oscillation signal, the cylinder pressure signal needs to be decomposed. Therefore, effective signal extraction techniques are crucial for the analysis of high-frequency pressure oscillation signals. Wavelet packet transform is the most widely used signal feature extraction method. However, there is serious frequency confusion in the traditional wavelet packet transform, so many improved wavelet packet transform methods have been proposed, among which "...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G06K9/00G06N3/00G06N3/12H03H17/02
CPCH03H17/0211G06N3/006G06N3/126G06F2218/06G06F2218/08G06F2218/12
Inventor 杜敬涛陈曦明刘龙
Owner HARBIN ENG UNIV
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