A method and system for in-situ gear mesh impact extraction based on doppler effect compensation

Abstract

The application provides an in-situ gear meshing impact signal extraction method and system based on Doppler effect compensation. The method adopts at least two acceleration sensors to collect meshing vibration signals of a gear to be measured; extracts a high-frequency vibration acceleration component and a low-frequency gravity acceleration component of the meshing vibration signals collected by the acceleration sensors; extracts an instantaneous phase and an instantaneous frequency in the low-frequency gravity acceleration component; compensates the high-frequency vibration acceleration component based on the instantaneous frequency to restore the real frequency of the vibration signals generated at the meshing point; obtains a compensated high-frequency vibration acceleration component signal according to the real frequency and the high-frequency vibration acceleration component; and fuses the compensated high-frequency vibration acceleration component signal based on the instantaneous phase to obtain a gear meshing impact signal. The method restores the real frequency of the vibration signals generated at the meshing point through Doppler frequency shift compensation, and improves the precision of gear meshing impact signal extraction.

Description

Technical Field

[0001] This invention relates to the field of mechanical transmission testing, specifically to an in-situ gear meshing impact extraction method and system based on Doppler effect compensation. Background Technology

[0002] With the development of modern machinery towards higher speeds, lighter weights, greater precision, and automation, the dynamic behaviors such as vibration and noise generated during gear transmission have attracted widespread attention. Among these, meshing impact is the main cause of vibration, impact, and noise in gear transmission. Therefore, extracting and analyzing meshing impact during gear transmission is of great significance.

[0003] Existing embedded meshing impact extraction methods still have many shortcomings. On the one hand, the sensitivity direction of the accelerometer is fixed. As the gear rotates continuously during operation, the angle between the sensor's sensitivity direction and the meshing line also changes. When this angle is 90°, the accelerometer's sensitivity to meshing impact is zero, resulting in poor measurement performance. On the other hand, the gear rotates with the shaft within the gearbox, and the meshing point moves along the meshing line as the gear rotates. The in-situ sensor mounted on the gear also rotates with the gear. Consequently, the meshing impact signal experiences a Doppler effect during transmission from the meshing point to the in-situ sensor, causing a frequency shift in the measurement signal. This Doppler effect is particularly significant in applications with large gears and high measurement accuracy requirements, where it can have a substantial impact on the measurement results. Summary of the Invention

[0004] In order to overcome the defects existing in the prior art, the purpose of this invention is to provide a method and system for extracting in-situ gear meshing impact signals based on Doppler effect compensation.

[0005] To achieve the above-mentioned objectives of this invention, this invention provides a method for extracting in-situ gear meshing impact signals based on Doppler effect compensation, comprising the following steps:

[0006] At least two accelerometers are used to collect the meshing vibration signal of the gear under test;

[0007] Extract the high-frequency vibration acceleration component and the low-frequency gravitational acceleration component from the meshing vibration signals collected by at least two acceleration sensors;

[0008] Extract the instantaneous phase and instantaneous frequency from the low-frequency gravitational acceleration component;

[0009] Doppler frequency shift compensation is performed on the high-frequency vibration acceleration component corresponding to the same accelerometer based on the instantaneous frequency and instantaneous phase of any accelerometer to restore the true frequency of the vibration signal generated at the meshing point.

[0010] The true frequency is used as the frequency of the high-frequency vibration acceleration component of at least two acceleration sensors to obtain the high-frequency vibration acceleration component signal after compensation by the corresponding acceleration sensors.

[0011] The gear meshing impact signal is obtained by fusing the high-frequency vibration acceleration component signal compensated by at least two acceleration sensors with the instantaneous phase of the low-frequency gravity acceleration component of the corresponding acceleration sensor.

[0012] This method restores the true frequency of the vibration signal generated at the meshing point through Doppler frequency shift compensation, eliminates the influence of frequency shift, and improves the accuracy of gear meshing impact signal extraction.

[0013] In one alternative scheme of the in-situ gear meshing impact signal extraction method based on Doppler effect compensation, the acceleration sensor is set on the end face of the gear, all acceleration sensors are set on the same circumference with the center point of the gear as the center, and the installation angle between two adjacent acceleration sensors is 90° with the center point of the gear as the vertex, and the sensitivity direction angle between two adjacent acceleration sensors is 90°.

[0014] This alternative solution, through the combined arrangement of acceleration sensors, compensates for the inaccuracy in measuring meshing impact when the sensor's sensitive direction is at an angle to the meshing line direction, thereby improving the measurement effect of meshing impact.

[0015] In one alternative scheme of the in-situ gear meshing impact signal extraction method based on Doppler effect compensation, the acceleration sensor used for high-frequency vibration acceleration component signal fusion is at least one pair of acceleration sensors with an installation angle and a sensitivity direction angle of 90 degrees to each other.

[0016] In this alternative solution, only two acceleration sensors with an installation angle and a sensitivity direction angle of 90 degrees to each other can be set on the gear end face; alternatively, four acceleration sensors can be set on the gear end face, but the installation angle and sensitivity direction angle of two adjacent acceleration sensors are 90 degrees to each other. During calculation, the acceleration sensors are used in pairs, and the installation angle and sensitivity direction angle of the paired acceleration sensors are 90 degrees to each other.

[0017] In one option of the in-situ gear meshing impact signal extraction method based on Doppler effect compensation, wavelet transform is performed on the low-frequency gravitational acceleration component to extract the instantaneous phase of the low-frequency gravitational acceleration component.

[0018] Phase unwinding is performed on the instantaneous phase to convert it into the instantaneous rotation angle of the accelerometer.

[0019] The instantaneous angular velocity is obtained by differentiating the instantaneous rotation angle with respect to time, and the instantaneous frequency of the low-frequency gravitational acceleration component is obtained based on this instantaneous angular velocity.

[0020] This optional solution can quickly and accurately extract the instantaneous phase and instantaneous frequency of the low-frequency gravitational acceleration component.

[0021] In one alternative scheme of the in-situ gear meshing impact signal extraction method based on Doppler effect compensation, the instantaneous velocity at the meshing point and the instantaneous velocity of the acceleration sensor are calculated.

[0022] Based on the Doppler effect, the true frequency of the meshing impact signal is obtained by using the instantaneous velocity of the meshing point and the velocity component of the instantaneous velocity of the acceleration sensor in the direction of the connection line between the meshing point and the sensor.

[0023] This optional solution can quickly and accurately restore the frequency at which the signal is emitted at the meshing point, improving the accuracy of gear meshing impact signal extraction.

[0024] In one option of this in-situ gear meshing impact signal extraction method based on Doppler effect compensation, the instantaneous velocity at the meshing point... The direction is along the meshing line; the instantaneous velocity V of the acceleration sensor S =ωr, with the direction along the tangent of the accelerometer's motion;

[0025] The actual frequency at which the meshing point generates a meshing impact signal is:

[0026]

[0027] Where A is the center point of the accelerometer, r is the distance from the gear center point O to point A, C is the intersection of the line of action and the base circle radius of the gear; B is the intersection of the perpendicular line drawn from point A to the line of action and the line of action; AB refers to the straight-line distance between points A and B, BC refers to the straight-line distance between points B and C, and V... S 'The instantaneous velocity V of the accelerometer' S The velocity component V in the direction of the connection line between the engagement point and the accelerometer sensor. M 'V' represents the instantaneous velocity at the point of engagement. M The velocity component along the line connecting the engagement point and the accelerometer sensor, where θ is the instantaneous rotation angle. φ(t) is the instantaneous phase, unwrap(·) is the phase unwinding, and ω is the instantaneous angular velocity. f(θ) is the distance from the meshing point to point C when the instantaneous rotation angle is θ, and V is the propagation speed of the meshing impact signal. M Let be the instantaneous frequency of the low-frequency gravitational acceleration component of any accelerometer.

[0028] In one alternative scheme of the in-situ gear meshing impact signal extraction method based on Doppler effect compensation, the meshing impact signal generated at the meshing point is obtained by combining the high-frequency vibration acceleration component signals compensated by at least two acceleration sensors with the instantaneous phase projection in the direction of the meshing line through dynamic projection.

[0029] In one alternative scheme of this in-situ gear meshing impact signal extraction method based on Doppler effect compensation, when using two acceleration sensors, the meshing impact signal generated at the meshing point is calculated according to the following formula:

[0030]

[0031] in, The signal represents the high-frequency vibration acceleration components compensated by two accelerometers, where φ is the instantaneous phase, α is the gear pressure angle, and θ is the instantaneous rotation angle.

[0032] This invention also proposes an in-situ gear meshing impact signal extraction system, including at least two accelerometers disposed on the end face of the gear. All accelerometers are arranged on the same circumference centered on the gear's center point, with an installation angle of 90° between adjacent accelerometers and an angle of 90° between their sensitivity directions. The accelerometers are communicatively connected to a host computer, transmitting the collected gear meshing vibration signals to the host computer. The host computer extracts the in-situ gear meshing impact signals according to the aforementioned in-situ gear meshing impact signal extraction method based on Doppler effect compensation. This system possesses all the advantages of the aforementioned in-situ gear meshing impact signal extraction method based on Doppler effect compensation.

[0033] The beneficial effects of this invention are: by combining and arranging multiple sensors and compensating for Doppler frequency shift, this invention effectively restores the meshing impact signal generated at the meshing point, improves the accuracy of gear meshing impact signal extraction, and is particularly suitable for large gears and occasions with high measurement accuracy requirements.

[0034] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0036] Figure 1 This is a flowchart illustrating the present invention;

[0037] Figure 2 This is a schematic diagram of the accelerometer sensor arrangement;

[0038] Figure 3 This is a geometric relationship analysis diagram when restoring the true frequency of the vibration signal generated at the meshing point. Detailed Implementation

[0039] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0040] In the description of this invention, unless otherwise specified and limited, it should be noted that the terms "installation", "connection" and "linking" should be interpreted broadly. For example, they can refer to mechanical or electrical connections, or internal connections between two components. They can be direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0041] Example 1

[0042] like Figure 1 As shown, this invention provides a method for extracting in-situ gear meshing impact signals based on Doppler effect compensation, specifically including the following steps:

[0043] At least two accelerometers are installed on the end face of the gear under test to collect the meshing vibration signal of the gear. This embodiment uses two accelerometers as an example for detailed explanation; single-axis accelerometers are selected. In this embodiment, the two accelerometers are embedded on the end face of the gear under test, positioned on the same circumference with the center point of the gear as the center, with a 90° angle between their installation points and a 90° angle between their sensitivity directions.

[0044] The high-frequency vibration acceleration component and the low-frequency gravitational acceleration component of the meshing vibration signal collected by each accelerometer are extracted. In this embodiment, the meshing vibration signal collected by the accelerometer is subjected to high-pass and low-pass filtering using an FIR filter to obtain the high-frequency vibration acceleration signal and the low-frequency gravitational acceleration component corresponding to the accelerometer.

[0045] Then, the instantaneous phase and instantaneous frequency of the low-frequency gravitational acceleration component are extracted. Since the phase angle of the gear corresponds to the phase angle of its gravitational acceleration, in this embodiment, wavelet transform is first performed on the low-frequency gravitational acceleration component to extract its instantaneous phase; then, phase decoupling is performed on the instantaneous phase to convert it into the instantaneous rotation angle of the accelerometer; the instantaneous rotation angle is differentiated with respect to time to obtain the instantaneous angular velocity ω, and the instantaneous frequency of the low-frequency gravitational acceleration component is obtained based on this instantaneous angular velocity ω. This instantaneous frequency is used as the instantaneous meshing frequency of the gear rotation. The specific calculation process is as follows:

[0046] Wavelet transform of the low-frequency gravitational acceleration component: Among them, S g (t) represents the low-frequency gravitational acceleration signal of the gear after FIR filtering, where a is the scale parameter, b is the positioning parameter, the wavelet basis is the complex-valued Morlet wavelet, ψ() is the Morlet wavelet mother function, and t refers to time. The resulting wavelet transform W(a,b) is a complex-domain function, and its expression is:

[0047]

[0048] Among them, Re g ,ψ a,b >and Im g ,ψ a,b > represent the real and imaginary parts of the signal, respectively. a,b Let be the Morlet wavelet mother function with scale parameter a and positioning parameter b, where a(t) and φ(t) are the instantaneous amplitude and instantaneous phase of the signal, respectively. Where:

[0049]

[0050]

[0051] The instantaneous phase φ(t) of the low-frequency gravitational acceleration signal (i.e., the gravitational component of the vibration signal) of the gear is calculated using the above formula, with a value range of [-π, π]. Then, after phase decoupling, the instantaneous phase φ(t) is converted into the instantaneous rotation angle θ(t) of the accelerometer, as follows:

[0052]

[0053] In the formula, unwrap(·) represents phase unwinding, resulting in a continuous angular signal.

[0054] Differentiating the instantaneous rotation angle θ(t) with respect to time yields the instantaneous angular velocity ω(t), and simultaneously, the instantaneous frequency f of the gear rotation measured by the accelerometer is obtained. m .

[0055] ​​instantaneous angular velocity

[0056] instantaneous frequency

[0057] Where Z represents the number of teeth on the gear.

[0058] When the instantaneous frequency f is obtained m Then, based on the instantaneous frequency f of any acceleration sensor m Doppler frequency shift compensation is performed on the high-frequency vibration acceleration components corresponding to the same accelerometer to restore the true frequency of the vibration signal generated at the meshing point, i.e., the frequency at which the signal is emitted from the meshing point. Specifically,

[0059] Taking the first accelerometer as an example, it is installed at point A on the end face of the gear, that is, the center point of the first accelerometer is at point A, and the distance from the center point O of the gear to point A is r, as follows. Figure 3 As shown, CE is the line of engagement when the gear is running, C and E are the intersection points of the line of engagement and the base circle radius of the gear, D is the position of the instantaneous engagement point on the line of engagement, and R is the base circle radius of the gear.

[0060] Draw a perpendicular line from point A to the extension of the line of meshing CE; the intersection of this perpendicular line and the extension of CE is point B. Let β be the angle between AD and BD, and let OA and OC be the angle between them. Let θ be the instantaneous turning angle from the starting line OF to OA. The starting line OF is given by the user and is the position where the instantaneous phase is 0. f(θ) is the distance from the meshing point D to point C when the instantaneous turning angle is θ.

[0061] Based on geometric relationships, we can deduce:

[0062]

[0063] in:

[0064]

[0065]

[0066] The instantaneous velocity at the engagement point is denoted as V. M The direction is along the meshing line; the instantaneous velocity of the first accelerometer is denoted as V. S The direction is along the tangent of the motion of the first accelerometer.

[0067]

[0068] V S =ωr

[0069] according to Figure 3The angles between the meshing line CE and AD (the line connecting the meshing point and the first accelerometer sensor), and the angle between the meshing line CE and the tangent direction of the first accelerometer sensor, are β and β, respectively. Therefore V M With V S The velocity components along the direction of the connection line AD between the engagement point D and the first accelerometer sensor are as follows:

[0070]

[0071]

[0072]

[0073] Where α is the gear pressure angle.

[0074] According to the Doppler effect, when the signal generating point and the signal receiving point each have a moving speed, the frequency f of the signal received at the receiving point will be... M The frequency f of the signal emitted from the point of origin S The relationship is:

[0075]

[0076] Where V is the propagation speed of the meshing impact signal, is a known quantity, and the instantaneous frequency f is... m That is, the frequency f of the signal received at the receiving point. M The above formula can be used to compensate for the Doppler effect under rotational conditions and obtain the true frequency when the meshing point generates a meshing impact signal.

[0077] From the above formula, the true frequency of the vibration signal generated at the meshing point after compensating for the Doppler effect can be obtained as follows:

[0078]

[0079] The true frequency of the vibration signal generated at the meshing point is used as the frequency of the high-frequency vibration acceleration components of the two accelerometers, and the compensated high-frequency vibration acceleration component signals of the two accelerometers are obtained respectively. In this embodiment, the compensated high-frequency vibration acceleration component signal of the first accelerometer is denoted as... The high-frequency vibration acceleration component signal after compensation by the second accelerometer is denoted as:

[0080] The gear meshing impact signal is obtained by fusing the high-frequency vibration acceleration component signals compensated by the two accelerometers and the instantaneous phase of the low-frequency gravity acceleration component of the corresponding accelerometer.

[0081] This embodiment uses two acceleration sensors as an example, such as... Figure 2, 3 As shown, since the two accelerometers are mounted at a 90° angle on the gear end face, and the angle between the sensitivity directions of the two accelerometers is also always 90°, the high-frequency vibration acceleration component signals compensated by the two accelerometers are projected onto the meshing line direction and added together using the dynamic projection transformation method to obtain the meshing impact signal generated at the meshing point.

[0082]

[0083] in,

[0084] It should be noted that if two pairs of accelerometers are used to implement this method, the meshing impact signal extracted from the meshing vibration signal collected by each pair of accelerometers is calculated, and then the average value of the meshing impact signals extracted by the two pairs of accelerometers is taken to obtain the final meshing impact signal generated at the meshing point.

[0085] Example 2

[0086] This invention also provides an in-situ gear meshing impact signal extraction system, including at least two acceleration sensors disposed on the end face of the gear. All acceleration sensors are disposed on the same circumference with the center point of the gear as the center, and the installation angle between two adjacent acceleration sensors is 90° with the center point of the gear as the vertex, and the sensitivity direction angle between two adjacent acceleration sensors is 90°. The acceleration sensors are communicatively connected to a host computer and send the gear meshing vibration signals they have collected to the host computer. The host computer extracts the in-situ gear meshing impact signals according to the embodiment.

[0087] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A method for in-situ gear mesh impact signal extraction based on Doppler effect compensation, characterized in that, The method comprises the following steps: Collecting meshing vibration signals of the gear to be measured by using at least two acceleration sensors; The acceleration sensors are arranged on the end surface of the gear, all the acceleration sensors are arranged on the same circle with the center point of the gear as the center, the installation included angle between two adjacent acceleration sensors is 90° with the center point of the gear as the vertex, and the included angle of the sensitivity directions of the two adjacent acceleration sensors is 90°; Extracting high-frequency vibration acceleration components and low-frequency gravity acceleration components of the meshing vibration signals collected by the at least two acceleration sensors; Extracting instantaneous phase and instantaneous frequency in the low-frequency gravity acceleration components, specifically: Performing wavelet transform on the low-frequency gravity acceleration components to extract the instantaneous phase of the low-frequency gravity acceleration components; Phase unwrapping is performed on the instantaneous phase to convert the instantaneous phase into an instantaneous rotation angle of the acceleration sensor; The instantaneous rotation angle is derived with respect to time to obtain an instantaneous angular velocity, and the instantaneous frequency of the low-frequency gravity acceleration components is obtained based on the instantaneous angular velocity; Based on the instantaneous frequency and the instantaneous phase corresponding to any acceleration sensor, the high-frequency vibration acceleration components corresponding to the same acceleration sensor are compensated by Doppler shift to restore the real frequency of the vibration signal generated at the meshing point, specifically: Calculating the instantaneous speed of the meshing point and the instantaneous speed of the acceleration sensor; Based on the Doppler effect, the real frequency of the meshing point when generating the meshing impact signal is obtained by using the velocity components of the meshing point instantaneous speed and the acceleration sensor instantaneous speed in the direction of the meshing point and the sensor connecting line; The real frequency is taken as the frequency of the high-frequency vibration acceleration components of the at least two acceleration sensors to obtain the high-frequency vibration acceleration component signals of the corresponding acceleration sensors after compensation; The high-frequency vibration acceleration component signals of the at least two acceleration sensors after compensation are fused based on the instantaneous phase in the low-frequency gravity acceleration components of the corresponding acceleration sensors to obtain the gear meshing impact signal. The acceleration sensors for high-frequency vibration acceleration component signal fusion are at least one pair of acceleration sensors with installation included angles and sensitivity direction included angles of 90°.

2. The in-situ gear mesh impact signal extraction method based on Doppler effect compensation according to claim 1, characterized in that, The engagement point instantaneous velocity , direction along the engagement line; the acceleration sensor instantaneous velocity V 𝑆 = ωr, direction along the acceleration sensor motion tangent direction; The true frequency at which the engagement point generates the engagement impact signal is: , Wherein, A is the center point of the acceleration sensor, r is the distance from the gear center point O to point A, C is an intersection point of the meshing line and the gear base circle radius; B is the intersection point of the vertical line from point A to the meshing line, AB refers to the straight line distance between point A and point B, BC refers to the straight line distance between point B and point C, is the instantaneous speed of the acceleration sensor is the speed component in the direction of the meshing point and the acceleration sensor connecting line, is the instantaneous speed of the meshing point is the speed component in the direction of the meshing point and the acceleration sensor connecting line, is the instantaneous rotation angle, , is the instantaneous phase, is the phase unwrapping, is the instantaneous angular velocity, , is the instantaneous rotation angle is the distance from the meshing point to point C at the time, V is the propagation speed of the meshing impact signal, is the instantaneous frequency in the low-frequency gravity acceleration component of any acceleration sensor.

3. The in-situ gear mesh impact signal extraction method based on Doppler effect compensation according to claim 1, characterized in that, The high-frequency vibration acceleration component signals of the at least two acceleration sensors after compensation are combined with the instantaneous phase by dynamic projection method to obtain the meshing impact signal generated at the meshing point by adding in the direction of the meshing line.

4. The in-situ gear mesh impact signal extraction method based on Doppler effect compensation according to claim 1, characterized in that, When two acceleration sensors are used, the meshing impact signal generated at the meshing point is calculated according to the following formula: ， wherein, is the compensated high frequency vibration acceleration component signal of the two acceleration sensors, and a is the gear pressure angle, is the instantaneous rotation angle, , is the instantaneous phase, is the phase unwrapping.

5. An in-situ gear mesh impact signal extraction system, characterized by, The method comprises at least two acceleration sensors arranged on the end surface of the gear, all the acceleration sensors are arranged on the same circle with the center point of the gear as the center, the installation included angle between two adjacent acceleration sensors is 90°, and the included angle of the sensitivity directions of the two adjacent acceleration sensors is 90°; the acceleration sensors are in communication connection with the upper computer, and send the gear meshing vibration signals collected by the acceleration sensors to the upper computer, and the upper computer extracts the in-situ gear meshing impact signal according to the in-situ gear meshing impact signal extraction method based on Doppler effect compensation according to any one of claims 1-4.

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