Method for evaluating environmental micro-vibration of high-precision scientific device and storage medium

Abstract

The present application relates to a kind of environmental microvibration evaluation method and storage medium for high-precision scientific device, the method comprises the following steps: collecting the environmental microvibration signal of environment to be evaluated;Power spectrum method is applied to the environmental microvibration signal processing, obtains corresponding first power spectral density function;The first power spectral density function is converted into the second power spectral density function of vibration velocity;According to second power spectral density function, the speed root mean square in the full frequency range of high-precision scientific device is calculated;The evaluation index of high-precision scientific device is converted into speed index;Based on the comparison of the speed root mean square and speed index, the environmental microvibration evaluation result of environment to be evaluated is obtained.Compared with prior art, the reliability of high-precision scientific device environmental microvibration analysis and evaluation is improved.

Description

Technical Field

[0001] This invention relates to the field of environmental vibration, and in particular to a method and storage medium for evaluating environmental micro-vibrations of high-precision scientific devices. Background Technology

[0002] Modern high-tech industries such as semiconductors, integrated circuits, and precision optical systems are booming, and precision scientific instruments such as electron microscopes and nuclear magnetic resonance equipment are constantly being updated and iterated. The construction of major scientific facilities, represented by synchrotron radiation sources and free-electron lasers, is also in full swing. To meet their physical performance requirements and ensure normal operation, the use of these devices requires extremely stringent control standards for environmental micro-vibrations, placing very high demands on the analysis, evaluation, and prevention of micro-vibrations. Most precision scientific instruments are quite sensitive to environmental micro-vibrations, which can damage these instruments, reduce their accuracy, and cause unacceptable deviations. Therefore, the reduction or elimination of the impact of environmental micro-vibrations must be considered during laboratory planning, site selection, and construction.

[0003] Commonly used vibration evaluation indicators often set certain allowable values ​​for acceleration or velocity. Among them, the Generic Vibration Criteria, first proposed by BBN in the United States, is widely used in the field of high-tech precision instruments, applicable to high-tech precision instruments and equipment in multiple industries such as optical microscopes, lithography machines, nuclear magnetic resonance imaging devices, and nanotechnology research and development devices. It is a set of 1 / 3 octave band velocity spectra, with allowable root-mean-square vibration velocities decreasing from 50 μm / s to 0.78 μm / s, while the frequency is basically limited to between 1 Hz and 80 Hz, denoted as VC-A to VC-G vibration standard curves. For major high-precision scientific facilities such as synchrotron radiation sources and free-electron lasers, which are national-level major scientific and technological infrastructures, the control standards for environmental vibration are even more stringent. In their paper "Ground motion and comparison of various sites" (No. EUROTEV-REPORT-2005, 023, 2005), Amirikas et al. disclosed their method for analyzing and evaluating vibration signals obtained from environmental vibration tests at nearly 20 synchrotron radiation source laboratories worldwide. They directly solved the power spectral density by performing Fourier transform on the displacement signals obtained from on-site tests, i.e., the periodogram method, and then calculated the root mean square of the displacement within a specified frequency range as an evaluation index.

[0004] However, due to the lack of standardized evaluation methods for environmental vibrations across various high-precision scientific instruments, the data analysis phase inevitably requires the conversion of evaluation indices, a process that is quite cumbersome. Furthermore, commonly used numerical calculus algorithms introduce significant errors when converting acceleration, velocity, and displacement. In addition, the periodogram method, commonly used for solving power spectral density, has a large variance, leading to reduced accuracy in calculating the root mean square of the signal, making it difficult to meet the urgent needs of high-precision scientific instruments for precise analysis of environmental micro-vibrations. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a highly reliable method and storage medium for evaluating environmental micro-vibrations of high-precision scientific devices.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] An environmental micro-vibration evaluation method for high-precision scientific devices includes the following steps:

[0008] Collect environmental micro-vibration signals of the environment to be evaluated;

[0009] The environmental micro-vibration signal is processed using the power spectral density method to obtain the corresponding first power spectral density function;

[0010] The first power spectral density function is transformed into the second power spectral density function of vibration velocity;

[0011] Calculate the root mean square velocity of the high-precision scientific device across the entire frequency range based on the second power spectral density function;

[0012] Transform the evaluation indicators of high-precision scientific devices into speed indicators;

[0013] Based on the comparison between the root mean square velocity and the velocity index, the environmental micro-vibration evaluation results of the environment to be evaluated are obtained.

[0014] Furthermore, when collecting environmental micro-vibration signals of the environment to be evaluated, characteristic points in the site are selected based on the location of the high-precision scientific device and the foundation depth, and vibration time-domain data at the characteristic points are collected to form the environmental micro-vibration signals.

[0015] Furthermore, when collecting vibration time-domain data at the feature points, the sampling frequency is greater than twice the data analysis cutoff frequency.

[0016] Furthermore, the power spectral density method includes the Welch method and the Yule-Walker method, and the first power spectral density function is obtained by matching the length of the environmental micro-vibration signal to be processed using one of the Welch method and the Yule-Walker method.

[0017] Furthermore, when the length of the environmental micro-vibration signal to be processed is greater than the set value, the Welch method is used; otherwise, the Yule-Walker method is used.

[0018] Furthermore, the first power spectral density function is a signal acceleration power spectral density function, a signal velocity power spectral density function, or a signal displacement power spectral density function.

[0019] Furthermore, the full frequency range is 0.1 Hz to N Hz, where N is the smaller value between the data analysis cutoff frequency and the maximum frequency required for calculation by the high-precision scientific device.

[0020] Furthermore, when comparing the root mean square velocity and the velocity index, both the root mean square velocity and the velocity index are represented by a 1 / 3 octave band velocity spectrum.

[0021] Furthermore, the root mean square velocity, divided into 1 / 3 octave bands by the power spectrum, is expressed as:

[0022]

[0023] Among them, f l and f u These are the lower and upper limits of frequency for each band within a 1 / 3 octave band, respectively. v (ω) is the second power spectral density function, V RMS The root mean square of the velocity.

[0024] Furthermore, the evaluation index of the high-precision scientific device is a displacement index or an acceleration index.

[0025] The present invention also provides a computer-readable storage medium including one or more programs executable by one or more processors of an electronic device, said one or more programs including instructions for performing the environmental micro-vibration evaluation method for high-precision scientific devices as described above.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention transforms complex calculus operations into arithmetic operations by using a standardized method for power spectrum calculation and evaluation index conversion, thereby reducing systematic errors in the calculation process and improving the reliability of environmental micro-vibration evaluation.

[0028] 2. This invention uses different power spectrum methods to match the length of the environmental micro-vibration signal to be processed, which is highly targeted and improves the accuracy of evaluation.

[0029] 3. This invention integrates various analytical and evaluation methods for high-precision scientific devices into a unified and universal method, which can avoid the influence of differences in analytical methods on the analytical results, thereby improving the reliability of environmental micro-vibration analysis and evaluation of high-precision scientific devices and effectively reducing the risks of high-precision scientific device construction. Attached Figure Description

[0030] Figure 1 This is a schematic flowchart of the method of the present invention;

[0031] Figure 2 The environmental micro-vibration signals collected in the environment to be evaluated;

[0032] Figure 3 The following are power spectrum diagrams: 3-a is the power spectrum diagram of the vibration signal calculated by the Welch method, and 3-b is the power spectrum diagram of the vibration signal calculated by the Yule-Walker method.

[0033] Figure 4 The velocity power spectrum of the vibration signal;

[0034] Figure 5 The velocity spectrum is shown in the 1 / 3 octave band of the vibration signal.

[0035] Figure 6 The evaluation index of a certain high-precision scientific device (root mean square displacement of vibration within 1-100Hz ≤ 25nm) is converted into a velocity index and compared with the velocity spectrum of the vibration signal in 1 / 3 octave band. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0037] like Figure 1 As shown, this embodiment provides a method for evaluating environmental micro-vibrations of high-precision scientific devices, including the following steps:

[0038] Step 1: Collect environmental micro-vibration signals of the environment to be evaluated.

[0039] Based on the location and foundation depth of the high-precision scientific device, characteristic points in the site are selected for surveying, drilling, and sensor placement. Vibration time-domain data at the characteristic points are collected to form the environmental micro-vibration signal, which serves as test data.

[0040] In a specific implementation, when collecting vibration time-domain data, the sampling frequency is greater than twice the data analysis cutoff frequency, and each sample contains no less than 1024 data points.

[0041] Step 2: Process the environmental micro-vibration signal using the power spectrum method to obtain the corresponding first power spectral density function. The first power spectral density function can be a displacement power spectral density function, an acceleration power spectral density function, or a velocity power spectral density function, as needed.

[0042] In a specific implementation, a vibration signal x(n) is read from the environmental micro-vibration signal, such as... Figure 2 As shown, calculate the power spectral density function P. x (k) Specifically, the first power spectral density function can be obtained by matching the length of the environmental micro-vibration signal to be processed using either the Welch method or the Yule-Walker method. Specifically, the Welch method can better reflect the power spectral characteristics of the signal, and the longer the signal, the smaller the calculation variance; the Yule-Walker method can obtain higher resolution when solving the power spectrum for shorter signal lengths.

[0043] Method 1: Solve the power spectrum using the Welch method, the results are as follows Figure 3 -a is shown.

[0044] A signal x(n) of length N is divided into L segments, each segment having M data points. Adjacent segments overlap by m data points. The i-th segment can be represented as:

[0045] x i (n)=x(n+(i-1)(Mm)) (1)

[0046] By applying the window function w(n) to each signal segment, the periodogram of each segment is calculated. The periodogram of the i-th segment is as follows:

[0047]

[0048] Averaging the periodogram for each segment yields the power spectral density function:

[0049]

[0050] Method 2: Solve the power spectrum using the Yule-Walker method, and the results are as follows. Figure 3 -b is shown.

[0051] This method treats the test signal x(n) as a Gaussian white noise signal generated by a linear time-invariant minimum-phase system. The variance of the white noise signal is σ². The system can be described using an M-order AR model:

[0052]

[0053] Multiplying both sides of equation (4) by y(nl) and taking the expectation, we obtain the autocovariance function:

[0054]

[0055] Rewritten in matrix form, we obtain the Yule-Walker equations:

[0056]

[0057] Solving equation (6) yields the coefficients a1, a2, ..., a M The power spectral density function can be obtained as follows:

[0058]

[0059] In the process of solving the power spectral density, an appropriate window width, overlap length, or order should be adopted according to parameters such as the sampling rate. Specifically, the window width should be 4 to 10 times the sampling rate, the overlap length should be 1 / 3 to 1 / 2 of the window width, and the order should be 20 to 50.

[0060] Step 3: Transform the first power spectral density function into a second power spectral density function of vibration velocity, which is the velocity power spectral density function.

[0061] In a specific implementation, the first power spectral density function may be a signal acceleration power spectral density function, a signal velocity power spectral density function, or a signal displacement power spectral density function, determined based on the sensor type.

[0062] When the test signal is a displacement signal, the formula for calculating the velocity power spectrum of vibration velocity from the displacement power spectrum is:

[0063] P v (ω)=ω 2 P x (ω) (8)

[0064] When the test signal is an acceleration signal, the formula for calculating the velocity power spectrum of vibration velocity from the acceleration power spectrum is:

[0065]

[0066] Therefore, the power spectral density function P of the test signal can be obtained. x (n) is converted to the power spectral density function P of vibrational velocity. v (n). In this embodiment, the original signal is an acceleration signal, so the vibration velocity power spectrum can be obtained using equation (9). Taking the power spectrum obtained by method 1 as an example, as follows... Figure 4 As shown.

[0067] Step 4: Calculate the root mean square velocity of the high-precision scientific device across the entire frequency range based on the second power spectral density function obtained in Step 3.

[0068] In a specific implementation, the lowest frequency across the entire frequency range should be 0.1 Hz, and the highest frequency should not exceed the cutoff frequency and the maximum frequency calculated for high-precision scientific instruments, using the smaller of the two values. Specifically, it can be set to 0.1-100 Hz. This embodiment is based on the velocity power spectral density function P. v (n) Calculate the root mean square velocity (RMS) in the range of 0.1-100Hz. Divide the power spectrum into 27 frequency bands by 1 / 3 octave band, and calculate the RMS velocity value for each band as follows:

[0069]

[0070] Among them, f l and f u These are the lower and upper frequency limits for each band within a 1 / 3 octave band, respectively. The 1 / 3 octave band velocity spectrum of the vibration signal is shown below. Figure 5 As shown.

[0071] Step 5: Convert the evaluation index of the high-precision scientific device into a velocity index. Based on the comparison between the root mean square velocity and the velocity index, obtain the environmental micro-vibration evaluation result of the environment to be evaluated.

[0072] Similarly, the velocity index can be represented using a 1 / 3 octave band velocity spectrum. When the evaluation index is a displacement index, the formula for converting the displacement index to the velocity index is:

[0073] lg|V(ω)|=lgω+lg|X(ω)| (11)

[0074] When the evaluation index is an acceleration index, the formula for converting the acceleration index into a velocity index is:

[0075] lg|V(ω)|=-lgω+lg|A(ω)| (12)

[0076] In this embodiment, the evaluation index of the scientific device to be evaluated is the root mean square displacement of vibration within 1-100Hz ≤ 25nm, which is a displacement index. It is converted to the corresponding velocity index using equation (11), and it can be seen that it is a straight line in a logarithmic coordinate system, as shown below. Figure 6 As shown, the micro-vibration conditions of high-precision scientific devices can be evaluated, thus providing a data foundation for the subsequent construction of laboratories using high-precision scientific devices.

[0077] If the above methods are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0078] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for evaluating environmental micro-vibrations in high-precision scientific devices, characterized in that, Includes the following steps: Collect environmental micro-vibration signals of the environment to be evaluated; The environmental micro-vibration signal is processed using the power spectral density method to obtain the corresponding first power spectral density function; The first power spectral density function is transformed into the second power spectral density function of vibration velocity; Calculate the root mean square velocity of the high-precision scientific device across the entire frequency range based on the second power spectral density function; Transform the evaluation indicators of high-precision scientific devices into speed indicators; Based on the comparison between the root mean square velocity and the velocity index, the environmental micro-vibration evaluation results of the environment to be evaluated are obtained. The power spectral density method includes the Welch method and the Yule-Walker method. The first power spectral density function is obtained by matching one of the Welch method and the Yule-Walker method according to the length of the environmental micro-vibration signal to be processed. When the length of the environmental micro-vibration signal to be processed is greater than a set value, the Welch method is used; otherwise, the Yule-Walker method is used. The full frequency range is 0.1Hz~ N Hz, where, N Take the smaller value between the data analysis cutoff frequency and the maximum frequency required for calculation by high-precision scientific instruments.

2. The method for evaluating environmental micro-vibrations of high-precision scientific devices according to claim 1, characterized in that, When collecting environmental micro-vibration signals of the environment to be evaluated, characteristic points in the site are selected based on the location of the high-precision scientific device and the depth of the foundation. Vibration time-domain data at the characteristic points are collected to form the environmental micro-vibration signals.

3. The method for evaluating environmental micro-vibrations of high-precision scientific devices according to claim 1, characterized in that, The first power spectral density function is the signal acceleration power spectral density function, the signal velocity power spectral density function, or the signal displacement power spectral density function.

4. The method for evaluating environmental micro-vibrations of high-precision scientific devices according to claim 1, characterized in that, When comparing the root mean square velocity and the velocity index, both the root mean square velocity and the velocity index are expressed as a 1 / 3 octave band velocity spectrum.

5. The method for evaluating environmental micro-vibrations of high-precision scientific devices according to claim 4, characterized in that, The root mean square velocity, divided into 1 / 3 octave bands by the power spectrum, is expressed as: in, f l and f u These are the lower and upper frequency limits for each frequency band within a 1 / 3 octave band, respectively. The second power spectral density function, The root mean square of the velocity.

6. The method for evaluating environmental micro-vibrations of high-precision scientific devices according to claim 1, characterized in that, The evaluation index for the high-precision scientific device is the displacement index or the acceleration index.

7. A computer-readable storage medium, characterized in that, It includes one or more programs that are executed by one or more processors of an electronic device, the one or more programs including instructions for performing the environmental micro-vibration evaluation method for high-precision scientific devices as described in any one of claims 1-6.

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