CN103632017B - Based on the method that pattern recognition improves Internal Combustion Engine vibration signal signal to noise ratio - Google Patents

Abstract

Translated fromChinese

本发明公开了基于模式识别提高内燃机表面振动信号信噪比的方法，包括以下步骤：步骤一：建立往复惯性力激励响应信号模型；步骤二：辨识模型参数；步骤三：预测往复惯性力激励响应信号；步骤四：去除往复惯性力激励响应信号。本发明提出在曲柄转角域研究内燃机往复惯性力的变化规律，依据缸压激励和往复惯性力激励响应信号的耦合特点，利用模式识别的方法去除往复惯性力激励响应信号，实现缸压激励响应信号的提取，从而提高内燃机表面振动信号信噪比。利用高信噪比振动速度信号与缸内压升率信号的关系可以表征缸内燃烧状态，利用高信噪比的振动速度信号与缸内压升率信号的关系可以实现内燃机工作过程的在线识别及控制、故障诊断等。

The invention discloses a method for improving the signal-to-noise ratio of the surface vibration signal of an internal combustion engine based on pattern recognition, comprising the following steps: Step 1: Establishing a reciprocating inertial force excitation response signal model; Step 2: Identifying model parameters; Step 3: Predicting the reciprocating inertial force excitation response signal; Step 4: remove the reciprocating inertial force excitation response signal. The invention proposes to study the change law of the reciprocating inertial force of the internal combustion engine in the crank angle domain, and according to the coupling characteristics of the cylinder pressure excitation and the reciprocating inertial force excitation response signal, the method of pattern recognition is used to remove the reciprocating inertial force excitation response signal to realize the cylinder pressure excitation response signal Extraction, thereby improving the signal-to-noise ratio of the surface vibration signal of the internal combustion engine. Using the relationship between the high signal-to-noise ratio vibration velocity signal and the in-cylinder pressure rise rate signal can characterize the combustion state in the cylinder, and using the relationship between the high signal-to-noise ratio vibration velocity signal and the in-cylinder pressure rise rate signal can realize the online identification of the working process of the internal combustion engine And control, fault diagnosis, etc.

Description

Translated fromChinese

基于模式识别提高内燃机表面振动信号信噪比的方法A Method of Improving Signal-to-Noise Ratio of Surface Vibration Signal of Internal Combustion Engine Based on Pattern Recognition

技术领域technical field

本发明涉及一种信号处理新方法，具体涉及一种基于模式识别滤除内燃机表面振动激励响应信号中往复惯性力激励振动响应信号的方法。The invention relates to a new signal processing method, in particular to a method for filtering out the vibration response signal excited by reciprocating inertial force in the surface vibration excitation response signal of an internal combustion engine based on pattern recognition.

背景技术Background technique

内燃机表面振动信号是多种激励共同作用的结果，缸压激励的振动响应信号包含丰富的与缸内燃烧过程相关的信息，且振动传感器价格便宜、安装方便。因此，内燃机表面振动信号对内燃机工作过程及故障诊断等具有重要的意义。围绕着内燃机表面振动信号的分析和应用，国内外学者采用各种信号分析技术，做了大量的研究工作。AnyuChen采用短时傅里叶变换技术，可对内燃机表面振动信号中包含的燃烧激励、活塞撞击激励响应信号进行识别。Chiavola基于在一台双缸柴油机上所测振动信号的频域分析，设计了滤波器并提取出了650-1100Hz的机体振动信号成分。郑旭利用M-EMD集总平均经验模态分解方法对内燃机振动信号进行分解，实现了对燃烧激励响应信号和气门撞击激励响应信号的分离。KatarzynaBizon研究了基于径向基函数（RBF）神经网络，利用内燃机机体表面振动信号预测气缸压力以及与气缸压力相关的参数。The surface vibration signal of an internal combustion engine is the result of multiple excitations. The vibration response signal excited by the cylinder pressure contains a wealth of information related to the combustion process in the cylinder, and the vibration sensor is cheap and easy to install. Therefore, the surface vibration signal of the internal combustion engine is of great significance to the working process and fault diagnosis of the internal combustion engine. Around the analysis and application of internal combustion engine surface vibration signals, scholars at home and abroad have done a lot of research work using various signal analysis techniques. AnyuChen uses short-time Fourier transform technology to identify the combustion excitation and piston impact excitation response signals contained in the surface vibration signal of the internal combustion engine. Based on the frequency domain analysis of vibration signals measured on a two-cylinder diesel engine, Chiavola designed a filter and extracted the vibration signal components of the body at 650-1100 Hz. Zheng Xu used the M-EMD lumped average empirical mode decomposition method to decompose the vibration signal of the internal combustion engine, and realized the separation of the combustion excitation response signal and the valve impact excitation response signal. KatarzynaBizon studied the radial basis function (RBF) neural network based on the use of internal combustion engine body surface vibration signals to predict cylinder pressure and parameters related to cylinder pressure.

但是，上述研究对工作都以信号分析和处理技术为基础，内燃机表面振动信号中高频激励可以通过常规的信号处理手段可以去除，但是往复惯性力激励和缸压激励振动响应信号在时域及频域均出现重叠，难以实现在滤除干扰信号的同时保持有用信号的完整性。However, the above research and work are all based on signal analysis and processing technology. The high-frequency excitation in the internal combustion engine surface vibration signal can be removed by conventional signal processing methods, but the vibration response signals of reciprocating inertial force excitation and cylinder pressure excitation are in the time domain and frequency domain. Domains overlap, making it difficult to maintain the integrity of useful signals while filtering out interfering signals.

发明内容Contents of the invention

为解决现有技术存在的不足，本发明公开了基于模式识别提高内燃机表面振动信号信噪比的方法，本发明提出在曲柄转角域研究内燃机往复惯性力的变化规律，依据缸压激励和往复惯性力激励响应信号的耦合特点，利用模式识别的方法去除往复惯性力激励响应信号，实现缸压激励响应信号的提取，从而提高内燃机表面振动信号信噪比。In order to solve the deficiencies in the prior art, the present invention discloses a method for improving the signal-to-noise ratio of the surface vibration signal of an internal combustion engine based on pattern recognition. Based on the coupling characteristics of the force excitation response signal, the method of pattern recognition is used to remove the reciprocating inertial force excitation response signal, and the extraction of the cylinder pressure excitation response signal is realized, thereby improving the signal-to-noise ratio of the surface vibration signal of the internal combustion engine.

为实现上述目的，本发明的具体方案如下：To achieve the above object, the specific scheme of the present invention is as follows:

基于模式识别提高内燃机表面振动信号信噪比的方法，包括以下步骤：The method for improving the signal-to-noise ratio of internal combustion engine surface vibration signals based on pattern recognition comprises the following steps:

步骤一：依据内燃机往复惯性力的特点，建立往复惯性力激励响应信号模型；Step 1: According to the characteristics of the reciprocating inertial force of the internal combustion engine, the excitation response signal model of the reciprocating inertial force is established;

步骤二：辨识步骤一中的相关的模型参数；Step 2: Identify the relevant model parameters in Step 1;

步骤三：预测往复惯性力激励响应信号；Step 3: Predict the reciprocating inertial force excitation response signal;

步骤四：去除往复惯性力激励响应信号。Step 4: Remove the reciprocating inertial force excitation response signal.

所述步骤一内燃机往复惯性力二阶表达式为：The second-order expression of the reciprocating inertial force of the internal combustion engine in step 1 is:

P_j＝-mrω²(cosα+λcos2α)。P_j = -mrω² (cosα+λcos2α).

往复惯性力表达式求导得到：The derivation of the reciprocating inertial force expression gives:

$\frac{{<span><span>\&PartialD;</span>\&PartialD;</span>\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}{<span><span>\&PartialD;</span>\&PartialD;</span>\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}<span><span>=</span>=</span>\mathrm{<span><span>mr</span>mr</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>)</span>)</span><span><span>=</span>=</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>.</span>.</span>$

假设往复惯性力激励响应信号与往复惯性力导数之间只存在相位和幅值上的变化，因此得到假设的往复惯性力激励响应信号表达式：Assuming that there are only changes in phase and amplitude between the reciprocating inertial force excitation response signal and the reciprocating inertial force derivative, the hypothetical expression of the reciprocating inertial force excitation response signal is obtained:

${\mathrm{<span><span>V</span>V</span>}}_{{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}<span><span>=</span>=</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>3</span>3</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}<span><span>(</span>(</span>\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>)</span>)</span><span><span>+</span>+</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>4</span>4</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}<span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span><span><span>.</span>.</span>$

将往复惯性力激励响应信号表达式线性化得到：Linearize the expression of the reciprocating inertial force excitation response signal to get:

${\mathrm{<span><span>V</span>V</span>}}_{{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}<span><span>=</span>=</span>{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>1</span>1</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>3</span>3</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>4</span>4</span>}}\mathrm{<span><span>cos</span>cos</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>)</span>)</span><span><span>.</span>.</span>$

令$Q=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{[v^{\&prime;}-n^2(B_1\sin {\mathrm{\&alpha;}}_i+B_2\cos {\mathrm{\&alpha;}}_i+B_3\sin 2{\mathrm{\&alpha;}}_i+B_4\cos 2{\mathrm{\&alpha;}}_i)]}^2$make$Q=\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}{[v^{\&prime;}-{\mathrm{no}}^2(B_1\sin {\mathrm{\&alpha;}}_i+B_2\cos {\mathrm{\&alpha;}}_i+B_3\sin 2{\mathrm{\&alpha;}}_i+B_4\cos 2{\mathrm{\&alpha;}}_i)]}^2$

上述辨识出模型参数是依据实测的振动速度信号，采用往复惯性力占主导地位的时段，利用最小二乘法基本原理对模型参数进行辨识，最小二乘法辨识模型参数原理如下：由多元函数Q(B₁,B₂,B₃,B₄)取得极值得必要条件求解B₁，B₂，B₃，B₄等模型参数。The above identification of model parameters is based on the measured vibration velocity signal, using the time period when the reciprocating inertial force is dominant, and using the basic principle of the least square method to identify the model parameters. The principle of the least square method identification model parameters is as follows: by the multivariate function Q(B₁ , B₂ , B₃ , B₄ ) Necessary conditions for obtaining extreme value Solve model parameters such as B₁ , B₂ , B₃ , and B₄ .

其中，p_j是j时刻的往复惯性力，其中j为自然数，m是往复运动质量，r是曲柄长度，ω是曲柄旋转角速度，α是曲柄转角，λ是连杆比，n是发动机转速，A₁,A₂,A₃,A₄是中间参数，用于描述相应公式中的常量部分，v'为实测振动速度信号，V_p是往复惯性力激励振动响应信号，α₁，α₂代表相位上的偏差角度，B₁，B₂，B₃，B₄是需要辨识的模型参数。Among them, p_j is the reciprocating inertial force at j moment, where j is a natural number, m is the reciprocating mass, r is the length of the crank, ω is the rotational angular velocity of the crank, α is the crank angle, λ is the connecting rod ratio, n is the engine speed, A₁ , A₂ , A₃ , and A₄ are intermediate parameters used to describe the constant part in the corresponding formula, v' is the measured vibration velocity signal, V_p is the vibration response signal excited by reciprocating inertial force, α₁ and α₂ represent The deviation angles on the phase, B₁ , B₂ , B₃ , B₄ are model parameters that need to be identified.

上述预测复惯性力激励响应信号，是利用上述辨识的模型参数结合瞬时转速信号来预测不同曲柄转角下往复惯性力激励响应信号。依据上述在往复惯性力占主导地位的时段得到的模型参数结合往复惯性力激励响应信号表达式，来推求往复惯性力与缸压激励共同作用的时段的往复惯性力激励响应信号。The aforementioned prediction of the complex inertial force excitation response signal is to use the above identified model parameters combined with the instantaneous rotational speed signal to predict the reciprocating inertial force excitation response signal at different crank angles. Based on the model parameters obtained during the period when the reciprocating inertial force dominates, combined with the expression of the reciprocating inertial force excitation response signal, the reciprocating inertial force excitation response signal for the period when the reciprocating inertial force and the cylinder pressure excitation act together is calculated.

上述去除往复惯性力激励响应信号即用实测的振动速度信号减去预测得到的往复惯性力激励响应信号，从而得到只有缸压激励作用的振动速度信号。The above-mentioned removal of the reciprocating inertial force excitation response signal is to subtract the predicted reciprocating inertial force excitation response signal from the measured vibration velocity signal, so as to obtain the vibration velocity signal with only cylinder pressure excitation.

本发明的有益效果：Beneficial effects of the present invention:

本发明提出了一种干扰信号与正常信号在时域及频域均出现重叠时的信号处理新方法。本发明提出在曲柄转角域研究内燃机往复惯性力的变化规律，依据缸压激励和往复惯性力激励响应信号的耦合特点，利用模式识别的方法去除往复惯性力激励响应信号，实现缸压激励响应信号的提取，从而提高内燃机表面振动信号信噪比。The invention proposes a new signal processing method when interference signals overlap with normal signals in time domain and frequency domain. The invention proposes to study the change law of the reciprocating inertial force of the internal combustion engine in the crank angle domain, and according to the coupling characteristics of the cylinder pressure excitation and the reciprocating inertial force excitation response signal, the method of pattern recognition is used to remove the reciprocating inertial force excitation response signal to realize the cylinder pressure excitation response signal Extraction, thereby improving the signal-to-noise ratio of the surface vibration signal of the internal combustion engine.

去除实测振动速度信号中往复惯性力激励的影响，提高振动速度信号的信噪比，利用振动速度信号与缸内压升率信号的关系可以表征缸内燃烧状态。利用高信噪比的振动速度信号与缸内压升率信号的关系可以实现内燃机工作过程的在线识别及控制、故障诊断等。The influence of reciprocating inertial force excitation in the measured vibration velocity signal is removed, the signal-to-noise ratio of the vibration velocity signal is improved, and the relationship between the vibration velocity signal and the in-cylinder pressure rise rate signal can be used to characterize the combustion state in the cylinder. Using the relationship between the vibration velocity signal with a high signal-to-noise ratio and the in-cylinder pressure rise rate signal can realize online identification and control of the internal combustion engine's working process, fault diagnosis, etc.

附图说明Description of drawings

图1为本发明提出的去除往复惯性力激励响应信号流程图。Fig. 1 is a flow chart of the excitation response signal for removing the reciprocating inertial force proposed by the present invention.

具体实施方式：detailed description:

下面结合附图对本发明进行详细说明：The present invention is described in detail below in conjunction with accompanying drawing:

如图1所示，本发明包括建立往复惯性力激励响应信号模型、辨识模型参数、预测复惯性力激励响应信号、去除往复惯性力激励响应信号。As shown in Figure 1, the present invention includes establishing a reciprocating inertial force excitation response signal model, identifying model parameters, predicting complex inertial force excitation response signals, and removing reciprocating inertial force excitation response signals.

本发明的原理：在低频域内，发动机缸盖表面振动速度信号是由缸压激励响应信号和往复惯性力激励响应信号叠加而成的，在已知振动速度信号的前提下，利用无缸压时段的振动速度信号推求往复惯性力激励响应模型，结合往复惯性力的变化规律，推求往复惯性力激励响应信号在整个角度域上的变化规律。The principle of the present invention: in the low frequency domain, the vibration velocity signal of the engine cylinder head surface is formed by superimposing the excitation response signal of the cylinder pressure and the excitation response signal of the reciprocating inertial force. The excitation response model of the reciprocating inertial force is derived from the vibration velocity signal, and the change law of the excitation response signal of the reciprocating inertial force in the entire angle domain is calculated in combination with the change law of the reciprocating inertial force.

往复惯性力激励响应信号模型的建立是基于往复惯性力数学模型。The establishment of the reciprocating inertial force excitation response signal model is based on the reciprocating inertial force mathematical model.

以一阶和二阶往复惯性力之和模型为例，基于一阶和二阶往复惯性力之和表达式：Taking the sum model of the first-order and second-order reciprocating inertial forces as an example, based on the expression of the sum of the first-order and second-order reciprocating inertial forces:

P_j＝-mrω²(cosα+λcos2α)，P_j =-mrω² (cosα+λcos2α),

对往复惯性力求导得到：Deriving the reciprocating inertial force gives:

$\frac{{<span><span>\&PartialD;</span>\&PartialD;</span>\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}{<span><span>\&PartialD;</span>\&PartialD;</span>\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}<span><span>=</span>=</span>\mathrm{<span><span>mr</span>mr</span>}{\mathrm{<span><span>\&omega;</span>\&omega;</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&lambda;</span>\&lambda;</span>}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>)</span>)</span><span><span>=</span>=</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>1</span>1</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>2</span>2</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>,</span>,</span>$

往复惯性力激励响应信号与往复惯性力导数之间只存在相位和幅值上的变化，因此得到假设的往复惯性力激励响应信号表达式：There are only phase and amplitude changes between the reciprocating inertial force excitation response signal and the reciprocating inertial force derivative, so the hypothetical expression of the reciprocating inertial force excitation response signal is obtained:

${\mathrm{<span><span>V</span>V</span>}}_{{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}<span><span>=</span>=</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>3</span>3</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}<span><span>(</span>(</span>\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}_{\mathrm{<span><span>1</span>1</span>}}<span><span>)</span>)</span><span><span>+</span>+</span>{\mathrm{<span><span>A</span>A</span>}}_{\mathrm{<span><span>4</span>4</span>}}{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}<span><span>(</span>(</span>\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}}_{\mathrm{<span><span>2</span>2</span>}}<span><span>)</span>)</span><span><span>,</span>,</span>$

将上述模型表达式线性化得到：Linearize the above model expression to get:

${\mathrm{<span><span>V</span>V</span>}}_{{\mathrm{<span><span>P</span>P</span>}}_{\mathrm{<span><span>j</span>j</span>}}}<span><span>=</span>=</span>{\mathrm{<span><span>n</span>no</span>}}^{\mathrm{<span><span>2</span>2</span>}}<span><span>(</span>(</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>1</span>1</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>2</span>2</span>}}\mathrm{<span><span>cos</span>cos</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>3</span>3</span>}}\mathrm{<span><span>sin</span>sin</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>+</span>+</span>{\mathrm{<span><span>B</span>B</span>}}_{\mathrm{<span><span>4</span>4</span>}}\mathrm{<span><span>cos</span>cos</span>}\mathrm{<span><span>2</span>2</span>}\mathrm{<span><span>\&alpha;</span>\&alpha;</span>}<span><span>)</span>)</span><span><span>,</span>,</span>$

令$Q=\underset{i=1}{\overset{n}{\mathrm{\&Sigma;}}}{[v^{\&prime;}-n^2(B_1\sin {\mathrm{\&alpha;}}_i+B_2\cos {\mathrm{\&alpha;}}_i+B_3\sin 2{\mathrm{\&alpha;}}_i+B_4\cos 2{\mathrm{\&alpha;}}_i)]}^2$make$Q=\underset{i=1}{\overset{\mathrm{no}}{\mathrm{\&Sigma;}}}{[v^{\&prime;}-{\mathrm{no}}^2(B_1\sin {\mathrm{\&alpha;}}_i+B_2\cos {\mathrm{\&alpha;}}_i+B_3\sin 2{\mathrm{\&alpha;}}_i+B_4\cos 2{\mathrm{\&alpha;}}_i)]}^2$

上述辨识出模型参数是依据实测的振动速度信号，采用往复惯性力占主导地位的时段，利用最小二乘法基本原理对模型参数进行辨识，由多元函数Q(B₁,B₂,B₃,B₄)取得极值得必要条件$\frac{\&PartialD;Q}{{\&PartialD;B}_1}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_2}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_3}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_4}=0$求解B₁，B₂，B₃，B₄等模型参数，The above identified model parameters are based on the measured vibration velocity signal, using the time period when the reciprocating inertial force is dominant, using the basic principle of the least square method to identify the model parameters, and the multivariate function Q(B₁ ,B₂ ,B₃ ,B₄ ) Obtain the necessary condition of extreme value$\frac{\&PartialD;Q}{{\&PartialD;B}_1}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_2}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_3}=0,$$\frac{\&PartialD;Q}{{\&PartialD;B}_4}=0$ Solve model parameters such as B₁ , B₂ , B₃ , B₄ , etc.,

其中p_j是j时刻的往复惯性力，其中j为自然数，m是往复运动质量，r是曲柄长度，ω是曲柄旋转角速度，α是曲柄转角，λ是连杆比，n是发动机转速，A₁,A₂,A₃,A₄是中间参数，用于描述相应公式中的常量部分，为模型预测的往复惯性力激励信号，Q是模型预测值与测量值间的差值的平方和，v′是振动速度信号实测值，，α₁，α₂代表相位上的偏差角度，B₁，B₂，B₃，B₄是需辨识的模型参数。where p_j is the reciprocating inertial force at time j, where j is a natural number, m is the reciprocating mass, r is the length of the crank, ω is the rotational angular velocity of the crank, α is the crank angle, λ is the connecting rod ratio, n is the engine speed, A₁ , A₂ , A₃ , A₄ are intermediate parameters, used to describe the constant part in the corresponding formula, is the reciprocating inertial force excitation signal predicted by the model, Q is the sum of the squares of the difference between the model predicted value and the measured value, v′ is the measured value of the vibration velocity signal, α₁ , α₂ represent the deviation angle on the phase, B₁ , B₂ , B₃ , B₄ are the model parameters to be identified.

预测复惯性力激励响应信号，是利用上述辨识的模型参数结合瞬时转速信号来预测不同曲柄转角下往复惯性力激励响应信号。依据上述在往复惯性力占主导地位的时段得到的模型参数结合往复惯性力激励响应信号表达式，来推求往复惯性力与缸压激励共同作用的时段的往复惯性力激励响应信号；The prediction of the excitation response signal of the complex inertial force is to use the model parameters identified above combined with the instantaneous speed signal to predict the excitation response signal of the reciprocating inertial force at different crank angles. Based on the above model parameters obtained during the period when the reciprocating inertial force dominates, combined with the expression of the reciprocating inertial force excitation response signal, the reciprocating inertial force excitation response signal for the period when the reciprocating inertial force and the cylinder pressure excitation act together;

去除往复惯性力激励响应信号即用实测的振动速度信号减去预测得到的往复惯性力激励响应信号，从而得到只有缸压激励作用的振动速度信号。Removing the reciprocating inertial force excitation response signal is to subtract the predicted reciprocating inertial force excitation response signal from the measured vibration velocity signal, so as to obtain the vibration velocity signal with only cylinder pressure excitation.

Claims (1)

1. The method for improving the signal-to-noise ratio of the vibration signal of the surface of the internal combustion engine based on pattern recognition is characterized by comprising the following steps of:

the method comprises the following steps: establishing a reciprocating inertial force excitation response signal model;

step two: identifying relevant model parameters in the first step;

step three: predicting a reciprocating inertia force excitation response signal;

step four: removing the reciprocating inertia force excitation response signal;

the second-order expression of the reciprocating inertia force of the internal combustion engine in the first step is as follows:

P_j＝-mrω²(cosα+λcos2α)，

wherein p is_jIs the reciprocating inertial force at time j, j is a natural number, m is the reciprocating mass, r is the crank length, ω is the crank rotation angular velocity, α is the crank angle, λ is the link ratio;

the reciprocal inertial force expression is derived as follows:

$\frac{\&part;P_j}{\&part;\mathrm{\&alpha;}}={\mathrm{mr\&omega;}}^2(\sin \mathrm{\&alpha;}+2\mathrm{\&lambda;}\sin 2\mathrm{\&alpha;})=A_1{n}^{2}sin\mathrm{\&alpha;}+A_1{n}^{2}sin2\mathrm{\&alpha;},$

wherein A is₁，A₂Is an intermediate parameter used to describe the constant in the formula;

assuming that there is only a change in phase and amplitude between the reciprocating inertial force excitation response signal and the reciprocating inertial force derivative, a hypothetical reciprocating inertial force excitation response signal expression is obtained:

$V_{P_j}=A_3{n}^{2}cos(\mathrm{\&alpha;}+{\mathrm{\&alpha;}}_1)+A_4{n}^{2}cos(2\mathrm{\&alpha;}+{\mathrm{\&alpha;}}_2),$

wherein,reciprocating inertial force excitation signal predicted for model, n is engine speed, α₁，α₂Representing the angle of deviation in phase, A₃,A₄Is an intermediate parameter used to describe the constant in the formula;

and linearizing the expression of the reciprocating inertia force excitation response signal to obtain:

$V_{P_j}=n^2(B_{1}sin\mathrm{\&alpha;}+B_{2}cos\mathrm{\&alpha;}+B_{3}sin2\mathrm{\&alpha;}+B_{4}cos2\mathrm{\&alpha;}),$

wherein, B₁，B₂，B₃，B₄Is the model parameter to be identified;

the specific process of the second step is as follows:

order to$Q=\underset{i=1}{\overset{n}{\&Sigma;}}{\&lsqb;v^{\&prime;}-n^2(B_1{\mathrm{sin\&alpha;}}_i+B_2{\mathrm{cos\&alpha;}}_i+B_{3}sin2{\mathrm{\&alpha;}}_i+B_{4}cos2{\mathrm{\&alpha;}}_i)\&rsqb;}^2$

The above-mentioned model parameters are identified based on actual measurementThe vibration speed signal is identified by adopting the time interval with the reciprocating inertia force in the dominant position and utilizing the basic principle of the least square method, and the model parameter is identified by a multivariate function Q (B)₁,B₂,B₃,B₄) Obtaining the necessary condition for extreme value$\frac{\&part;Q}{\&part;B_1}=0,\frac{\&part;Q}{\&part;B_2}=0,\frac{\&part;Q}{\&part;B_3}=0,\frac{\&part;Q}{\&part;B_4}=0$Solving for B₁，B₂，B₃，B₄Obtaining the parameters of the model and the parameters of the model,

wherein Q is the square of the difference between the predicted value and the measured value of the model, v' is the measured value of the vibration velocity signal, α_iRepresenting the crank angle at the moment i, wherein i is a natural number;

predicting a complex inertia force excitation response signal in the third step, namely predicting reciprocating inertia force excitation response signals under different crank angles by using the identified model parameters and combining instantaneous rotating speed signals;

and fourthly, removing the reciprocating inertia force excitation response signal, namely subtracting the predicted reciprocating inertia force excitation response signal from the measured vibration speed signal, thereby obtaining the vibration speed signal only with the cylinder pressure excitation effect.