Method and system for detecting electrical connection state of wiring terminal

Abstract

The invention relates to the technical field of wiring terminal connection state detection, and provides a wiring terminal electrical connection state detection method and system, and the method comprises the steps: collecting vibration data of different fixed frequencies in a wiring terminal electrical connection state, and obtaining a vibration sequence of the fixed frequencies; extracting a reconstruction signal of the vibration sequence with the fixed frequency, and determining the time domain consistency of the reconstruction signal; determining the main frequency concentration degree and the resonance saliency of the reconstructed signal, and obtaining the loosening possibility of the reconstructed signal according to the time domain consistency and the resonance saliency of the reconstructed signal; according to all the reconstruction signals of the vibration sequence of the same fixed frequency, the looseness degree of the wiring terminal at the same fixed frequency is determined, and according to the looseness degree of the wiring terminal at all the fixed frequencies, the detection result of the electrical connection state of the wiring terminal is obtained. The accuracy of the detection result of the electrical connection state of the wiring terminal can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of detecting the connection state of a terminal block, and particularly relates to a method and a system for detecting the electrical connection state of a terminal block. Background Art

[0002] A terminal block is a component for electrical connection, mainly used to realize the connection between wires or cables in an electrical circuit and electrical equipment. To ensure the safety and stability of the electrical system, it is necessary to detect the electrical connection state of the terminal block. Generally, for the detection of the electrical connection state of a terminal block, an external stimulus is applied to the joint position of the terminal block to cause the joint of the terminal block to vibrate, the vibration data is collected, and the looseness degree of the terminal block is evaluated according to the amplitude of the vibration data, so as to obtain the detection result of the electrical connection state of the terminal block.

[0003] However, the vibration of the terminal joint caused by applying an external stimulus may cause resonance of the joint. That is to say, the collected vibration data includes not only the vibration of the terminal joint caused by the external stimulus, but also the resonance of the joint. The resonance of the joint will affect the amplitude value of the vibration data, interfere with the evaluation of the looseness degree of the terminal block, and affect the stability and accuracy of the detection result of the electrical connection state of the terminal block. Summary of the Invention

[0004] The present invention provides a method and a system for detecting the electrical connection state of a terminal block to solve the problem that the resonance of the joint interferes with the evaluation of the looseness degree of the terminal block and makes the detection result of the electrical connection state of the terminal block inaccurate. The specific technical solutions adopted are as follows: In a first aspect, an embodiment of the present invention provides a method and a system for detecting the electrical connection state of a terminal block. The method includes the following steps: Under the electrical connection state of the terminal block, collect vibration data of a preset number of different fixed frequencies, and obtain the vibration sequence of the same fixed frequency according to the vibration data of the same fixed frequency; For any one fixed frequency, extract the frame signal of the reconstructed signal of the vibration sequence of the fixed frequency, construct the peak histogram and the valley histogram of the frame signal, and determine the time-domain consistency of the reconstructed signal according to the similarity between the peak histograms of different frame signals of the reconstructed signal and the similarity between the valley histograms; Determine the main frequency of the reconstructed signal, determine the main frequency concentration degree of the reconstructed signal according to the difference between the frequency with an amplitude greater than 0 and the main frequency in the frequency spectrum diagram of the reconstructed signal, and the difference between the amplitude greater than 0 and the amplitude of the main frequency. Determine the resonance significance degree of the reconstructed signal according to the main frequency of the reconstructed signal, the fixed frequency of the vibration sequence corresponding to the reconstructed signal, and the main frequency concentration degree of the reconstructed signal. Obtain the looseness possibility of the reconstructed signal according to the time-domain consistency and the resonance significance degree of the reconstructed signal. Determine the degree of looseness of the terminal at the same fixed frequency based on all the reconstructed signals of the vibration sequence at the same fixed frequency, and obtain the detection result of the electrical connection state of the terminal according to the degree of looseness of the terminal at all fixed frequencies.

[0005] Furthermore, the method for extracting the frame signals of the reconstructed signals of the vibration sequence at the fixed frequency and constructing the peak histogram and valley histogram of the frame signals specifically includes: Perform wavelet packet decomposition on the vibration sequence at the fixed frequency to obtain the reconstructed signals of all nodes in the last layer of the wavelet packet of the vibration sequence, and use a Hamming window to perform frame windowing processing on the reconstructed signals to obtain the frame signals of the reconstructed signals; Perform smoothing processing on the frame signals, use the second-order difference recognition algorithm for signal peaks and valleys to extract all the peaks and valleys in the smoothed frame signals, and construct the peak histogram of the frame signals with the amplitude of the peaks and the number of occurrences of the peaks as the horizontal and vertical coordinates of the histogram respectively, and construct the valley histogram of the frame signals with the amplitude of the valleys and the number of occurrences of the valleys as the horizontal and vertical coordinates of the histogram respectively.

[0006] Furthermore, the method for determining the time-domain consistency of the reconstructed signals is as follows: Denote the Bhattacharyya coefficient between the peak histograms of two different frame signals of the reconstructed signal as the first similarity of the two different frame signals of the reconstructed signal, and denote the mean value of the first similarities of all different frame signals of the reconstructed signal as the peak similarity of the reconstructed signal; Denote the Bhattacharyya coefficient between the valley histograms of two different frame signals of the reconstructed signal as the second similarity of the two different frame signals of the reconstructed signal, and denote the mean value of the second similarities of all different frame signals of the reconstructed signal as the valley similarity of the reconstructed signal; Denote the mean value of the peak similarity and the valley similarity of the reconstructed signal as the time-domain consistency of the reconstructed signal.

[0007] Furthermore, the method for determining the main frequency of the reconstructed signal specifically includes: Extract the spectrogram of the reconstructed signal, and denote the frequency with the largest amplitude in the spectrogram of the reconstructed signal as the main frequency of the reconstructed signal.

[0008] Furthermore, the method for determining the main frequency concentration degree of the reconstructed signal is as follows: Wherein, represents the main frequency concentration degree of the th reconstructed signal of the vibration sequence at the fixed frequency ; represents the fixed frequency ; The amplitude of the main frequency of a reconstructed signal; Indicates a fixed frequency of the th amplitude greater than 0 in the spectrogram of the Indicates a fixed frequency of the main frequency of the th reconstructed signal; of the th frequency with an amplitude greater than 0 in the spectrogram of the th reconstructed signal; Indicates a fixed frequency of the number of amplitudes greater than 0 in the spectrogram of the

[0009] Further, the method for determining the resonance significance of the reconstructed signal is: Denote the absolute value of the difference between the main frequency of the reconstructed signal and the fixed frequency of the corresponding vibration sequence of the reconstructed signal as the first difference of the reconstructed signal; denote the normalized value of the ratio of the main frequency concentration degree of the reconstructed signal to the first difference as the resonance significance of the reconstructed signal.

[0010] Further, the method for obtaining the looseness possibility of the reconstructed signal according to the time-domain consistency and resonance significance of the reconstructed signal includes the following specific method: Denote the reciprocal of the sum value of the time-domain consistency and resonance significance of the reconstructed signal as the looseness eigenvalue of the reconstructed signal, and denote the normalized value of the looseness eigenvalue of the reconstructed signal as the looseness possibility of the reconstructed signal.

[0011] Further, the method for determining the looseness degree of the terminal at the same fixed frequency according to all the reconstructed signals of the vibration sequence at the same fixed frequency includes the following specific method: For any fixed frequency, assign 0 to the nodes corresponding to all the reconstructed signals with looseness possibility less than or equal to the looseness detection threshold in the vibration sequence of the fixed frequency, perform wavelet packet inverse transform on all the nodes in the last layer of wavelet packets of the vibration sequence of the fixed frequency, and denote the signal obtained by the wavelet packet inverse transform as the cleaning data of the fixed frequency; Denote the mean value of all the cleaning data of the fixed frequency as the looseness degree of the terminal at the fixed frequency.

[0012] Further, the method for obtaining the detection result of the electrical connection state of the terminal according to the looseness degree of the terminal at all fixed frequencies includes the following specific method: Perform a linear fit on the fixed frequency and the degree of looseness of the terminal at the fixed frequency to obtain the slope of the fitted line. Denote the normalized value of the product of the mean of the degree of looseness of the terminal at all fixed frequencies and the slope of the fitted line as the stability detection evaluation value of the terminal. When the stability detection evaluation value of the terminal is greater than the stability detection threshold, determine that the terminal is a defective product. When the stability detection evaluation value of the terminal is less than or equal to the stability detection threshold, determine that the terminal is a qualified product.

[0013] In a second aspect, an embodiment of the present invention further provides a system for detecting the electrical connection state of a terminal, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of the method described in any one of the above are implemented.

[0014] The beneficial effects of the present invention are as follows: In this application, when the joint of the terminal is loose, the joint will exhibit normal vibrations, resonances, and abnormal vibrations caused by looseness. By analyzing the characteristics, since the abnormal vibrations caused by looseness will disrupt the regularity and consistency of the vibration data, resulting in abnormal peaks and valleys, the similarities between the peak histograms and valley histograms of different frame signals of the reconstructed signal are analyzed to determine the time-domain consistency of the reconstructed signal. When the time-domain consistency of the reconstructed signal is greater, the consistency of the peak distribution and valley distribution of the reconstructed signal is greater, and the reconstructed signal is more likely to correspond to the vibration data collected when the joint of the terminal is tightly connected; according to the characteristics that when the joint is relatively stable and no looseness occurs, the response of the system to external excitation reaches the maximum at the resonance frequency, and the energy in the collected vibration data is mainly concentrated near the resonance frequency, and when the joint is loose, the energy in the vibration data is dispersed throughout the frequency range, the main frequency concentration and resonance significance of the reconstructed signal are determined, and based on the time-domain consistency and resonance significance of the reconstructed signal, the loosening possibility of the reconstructed signal is obtained; finally, according to all the reconstructed signals of the vibration sequence at the same fixed frequency, the degree of looseness of the terminal when used at the fixed frequency is evaluated, the degree of looseness of the terminal at the fixed frequency is determined, and based on the degree of looseness of the terminal at all fixed frequencies, the detection result of the electrical connection state of the terminal is obtained, solving the problem that the joint resonance interferes with the evaluation of the looseness degree of the terminal, making the detection result of the electrical connection state of the terminal inaccurate, and improving the accuracy and stability of the detection result of the electrical connection state of the terminal. Description of the Drawings

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 Flow schematic diagram of a method and system for detecting the electrical connection state of a terminal block according to an embodiment of the present invention; Figure 2 Flowchart for obtaining time-domain consistency according to an embodiment of the present invention. Detailed implementation manners

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] Please refer to Figure 1 , which shows a flowchart of a method and system for detecting the electrical connection state of a terminal block according to an embodiment of the present invention. The method includes the following steps: Step S001, in the electrical connection state of the terminal block, collect vibration data of a preset number of different fixed frequencies, and obtain a vibration sequence of the same fixed frequency according to the vibration data of the same fixed frequency.

[0019] Use a terminal block to connect a wire and an electrical device. Install a micro vibration sensor at the wire hole joint position where the terminal block is connected to the electrical device. Connect the vibration platform to the electrical device and ensure that the vibration platform and the electrical device are at the same horizontal position. Use the vibration platform to apply vibrations of different fixed frequencies to the electrical device. Use the micro vibration sensor to collect the vibration data during each fixed frequency vibration. Arrange the vibration data collected during the same fixed frequency vibration in the order of collection time to obtain a vibration sequence of the fixed frequency.

[0020] Preferably, in an embodiment of the present application, the number of different fixed frequencies is 10. In this embodiment, the values of the fixed frequencies are 100 Hz, 125 Hz, 150 Hz, 175 Hz, 200 Hz, 225 Hz, 250 Hz, 275 Hz, 300 Hz, and 325 Hz respectively. The sampling frequency of the vibration data is 1000 Hz, and the acquisition duration of the vibration data is 1 second. In actual application processes, as other implementation manners, the implementer can determine the number of different fixed frequencies, the values of the fixed frequencies, the sampling frequency of the vibration data, and the value of the acquisition duration of the vibration data according to actual situations. The present application does not make special restrictions. In particular, the sampling frequency of the vibration data needs to ensure that it is at least twice the maximum value of the fixed frequencies.

[0021] Thus, vibration sequences with different fixed frequencies are obtained.

[0022] Step S002, for any one of the fixed frequencies, extract the frame signals of the reconstructed signal of the vibration sequence with the fixed frequency, construct the peak histogram and the valley histogram of the frame signals, and determine the time-domain consistency of the reconstructed signal according to the similarity between the peak histograms of different frame signals of the reconstructed signal and the similarity between the valley histograms.

[0023] When a vibration with a fixed frequency is applied to the joint position of the wiring terminal, the joint of the wiring terminal vibrates accordingly. When the joint is relatively stable and no loosening occurs, the joint will only experience normal vibrations. Therefore, the vibration data shows regularity and consistency, and no abnormal peaks and valleys will appear; when the joint becomes loose, the joint will experience normal vibrations, resonance, and abnormal vibrations caused by loosening. The regularity and consistency of the vibration data will be destroyed, and abnormal peaks and valleys will appear.

[0024] Extract the frame signals of the reconstructed signal of the vibration sequence with the fixed frequency, and construct the peak histogram and the valley histogram of the frame signals.

[0025] Perform wavelet packet decomposition on the vibration sequence with a fixed frequency to obtain the reconstructed signals of all nodes in the last layer of the wavelet packet for the vibration sequence. The reconstructed signals can provide the time-domain signal distribution information of the vibration data in the vibration sequence within different frequency ranges. Use a Hamming window to perform frame windowing on the reconstructed signals to obtain the frame signals of the reconstructed signals. Use a filtering and denoising algorithm to smooth the frame signals to reduce the influence of the noise in the frame signals on the subsequent extraction of peaks and valleys. Use the signal peak-valley second-order difference identification algorithm to extract all the peaks and valleys in the smoothed frame signals. Respectively, use the amplitude of the peaks and the number of occurrences of the peaks as the horizontal and vertical coordinates of the histogram to construct the peak histogram of the frame signals. Respectively, use the amplitude of the valleys and the number of occurrences of the valleys as the horizontal and vertical coordinates of the histogram to construct the valley histogram of the frame signals. The peak histogram and the valley histogram of the frame signals can provide the distribution information of the signal peaks and valleys in the time domain of the frame signals.

[0026] Among them, performing wavelet packet decomposition on the vibration sequence, using a Hamming window to perform frame windowing on the reconstructed signals, using a filtering and denoising algorithm to smooth the frame signals, and using the signal peak-valley second-order difference identification algorithm to extract all the peaks and valleys in the frame signals are all well-known techniques and will not be elaborated further. When performing wavelet packet decomposition on the vibration sequence in this embodiment, the number of layers of wavelet packet decomposition is taken as 3; it is a well-known technique and will not be elaborated further.

[0027] Determine the time-domain consistency of the reconstructed signals according to the similarity between the peak histograms of different frame signals of the reconstructed signals and the similarity between the valley histograms.

[0028] Preferably, as an embodiment of the present application, denote the Bhattacharyya coefficient between the peak histograms of two different frame signals of the reconstructed signals as the first similarity of the two different frame signals of the reconstructed signals, and denote the mean value of the first similarities of all different frame signals of the reconstructed signals as the peak similarity of the reconstructed signals; denote the Bhattacharyya coefficient between the valley histograms of two different frame signals of the reconstructed signals as the second similarity of the two different frame signals of the reconstructed signals, and denote the mean value of the second similarities of all different frame signals of the reconstructed signals as the valley similarity of the reconstructed signals; denote the mean value of the peak similarity and the valley similarity of the reconstructed signals as the time-domain consistency of the reconstructed signals.

[0029] The peak similarity of the reconstructed signal reflects the consistency of the peak distribution of the reconstructed signal in the time domain. When the consistency of the peak distribution of all frame signals of the reconstructed signal in the time domain is greater, the peak similarity of the reconstructed signal is greater. The valley similarity of the reconstructed signal reflects the consistency of the valley distribution of the reconstructed signal in the time domain. When the consistency of the valley distribution of all frame signals of the reconstructed signal in the time domain is greater, the valley similarity of the reconstructed signal is greater. When the peak similarity of the reconstructed signal is greater than the valley similarity, the time domain consistency of the reconstructed signal is greater. At this time, the consistency of the peak distribution of the reconstructed signal is greater, the consistency of the valley distribution is greater, and the reconstructed signal is more likely to correspond to the vibration data collected when the connector of the terminal block is tightly connected.

[0030] The calculation of the Bhattacharyya coefficient is a well-known technique and will not be described in detail.

[0031] It can be understood that each reconstructed signal has a corresponding time domain consistency, that is, the reconstructed signal of each node in the last layer of wavelet packet of the vibration sequence has a corresponding time domain consistency.

[0032] At this point, the time domain consistency of the reconstructed signal is obtained. The time domain consistency acquisition flow chart is as follows: Figure 2 shown.

[0033] Step S003, determine the main frequency of the reconstructed signal, determine the main frequency concentration of the reconstructed signal based on the difference between the frequency with an amplitude greater than 0 and the main frequency in the spectrum diagram of the reconstructed signal, and the difference between the amplitude greater than 0 and the amplitude of the main frequency, determine the resonance significance of the reconstructed signal based on the main frequency of the reconstructed signal, the fixed frequency of the vibration sequence corresponding to the reconstructed signal, and the main frequency concentration of the reconstructed signal, and obtain the looseness possibility of the reconstructed signal based on the time domain consistency and resonance significance of the reconstructed signal.

[0034] It should be noted that when the joint is relatively stable and not loose, if the fixed frequency is close to the natural frequency of the joint of the terminal block, the joint of the terminal block will resonate, causing the amplitude of the joint affected by the vibration platform to increase significantly. Since the system's response to external excitation reaches the maximum at the resonant frequency, the energy accumulation is most significant, so the energy in the vibration data collected at this time is mainly concentrated near the resonant frequency. When the joint is loose, the same fixed frequency affects the joint, and the looseness will cause the stiffness and damping characteristics of the joint to change, so that the energy in the collected vibration data is dispersed over the entire frequency range.

[0035] The frequency spectrum of the reconstructed signal is extracted using Fourier transform, and the frequency with the largest amplitude in the frequency spectrum of the reconstructed signal is recorded as the main frequency of the reconstructed signal. The main frequency of the reconstructed signal is the frequency component with the largest energy in the reconstructed signal.

[0036] Among them, extracting the spectrogram of the reconstructed signal using Fourier transform is a well-known technique and will not be elaborated here.

[0037] According to the differences between the frequencies with amplitudes greater than 0 and the main frequency, and between the amplitudes greater than 0 and the amplitude of the main frequency in the spectrogram of the reconstructed signal, the main frequency concentration degree of the reconstructed signal is determined.

[0038] Among them, represents the main frequency concentration degree of the th reconstructed signal of the vibration sequence with a fixed frequency ; represents the amplitude of the main frequency of the th reconstructed signal of the vibration sequence with a fixed frequency ; represents the th amplitude greater than 0 in the spectrogram of the th reconstructed signal of the vibration sequence with a fixed frequency ; represents the main frequency of the th reconstructed signal of the vibration sequence with a fixed frequency ; is an adjustment coefficient, whose function is to prevent the denominator from being 0. In this embodiment, the value of the adjustment coefficient is 0.01; represents the number of amplitudes greater than 0 in the spectrogram of the th reconstructed signal of the vibration sequence with a fixed frequency

[0039] The main frequency concentration degree is used to evaluate the degree to which the energy of the signal in the reconstructed signal is concentrated near the main frequency. When the differences between the frequencies with amplitudes greater than 0 and the main frequency, and between the amplitudes greater than 0 and the amplitude of the main frequency in the spectrogram of the reconstructed signal are smaller, the main frequency concentration degree of the reconstructed signal is larger, and the energy of the signal in the reconstructed signal is more concentrated near the main frequency.

[0040] According to the main frequency of the reconstructed signal, the fixed frequency of the corresponding vibration sequence of the reconstructed signal, and the main frequency concentration degree of the reconstructed signal, the resonance significance degree of the reconstructed signal is determined.

[0041] Preferably, as an embodiment of the present application, the absolute value of the difference between the main frequency of the reconstructed signal and the fixed frequency of the vibration sequence corresponding to the reconstructed signal is denoted as the first difference of the reconstructed signal, and the normalized value of the ratio of the main frequency concentration degree of the reconstructed signal to the first difference is denoted as the resonance significance degree of the reconstructed signal.

[0042] During the process of calculating the ratio, in order to avoid the situation where the denominator is zero, a preset value needs to be added to the denominator. In an embodiment of the preset value, the value is 0.01.

[0043] It should be noted that in this embodiment, the Z-Score standard normalization method is used to calculate the normalized value. In the actual application process, implementers can use other methods of existing technologies, such as the maximum-minimum normalization method, sigmoid function, etc., to calculate the normalized value, which is not limited here.

[0044] When the difference between the main frequency of the reconstructed signal and the fixed frequency of the vibration sequence corresponding to the reconstructed signal is smaller and the main frequency concentration degree of the reconstructed signal is larger, the energy of the signal in the reconstructed signal is more concentrated near the main frequency, and the main frequency of the reconstructed signal is closer to the fixed frequency of the joint of the terminal block. The reconstructed signal is more likely to be the vibration data component of the joint of the terminal block when resonance occurs. At this time, the resonance significance degree of the reconstructed signal is larger.

[0045] According to the time-domain consistency and resonance significance degree of the reconstructed signal, obtain the loosening possibility of the reconstructed signal.

[0046] Preferably, as an embodiment of the present application, the reciprocal of the sum value of the time-domain consistency and resonance significance degree of the reconstructed signal is denoted as the loosening eigenvalue of the reconstructed signal, and the normalized value of the loosening eigenvalue of the reconstructed signal is denoted as the loosening possibility of the reconstructed signal.

[0047] When the time-domain consistency and resonance significance degree of the reconstructed signal are larger, the reconstructed signal is more likely to correspond to the vibration data collected when the joint of the terminal block is tightly connected, and the loosening possibility of the reconstructed signal is smaller.

[0048] Thus, obtain the loosening possibility of the reconstructed signal.

[0049] Step S004, determine the loosening degree of the terminal block at the same fixed frequency according to all the reconstructed signals of the vibration sequence at the same fixed frequency, and obtain the detection result of the electrical connection state of the terminal block according to the loosening degrees of the terminal block at all fixed frequencies.

[0050] For any fixed frequency, compare the loosening probabilities of all reconstructed signals of the vibration sequence at the fixed frequency with the loosening detection threshold. Assign a value of 0 to the nodes corresponding to all reconstructed signals whose loosening probabilities are less than or equal to the loosening detection threshold. Perform inverse wavelet packet transform on all nodes in the last layer of wavelet packets of the vibration sequence at the fixed frequency, and denote the signal obtained from the inverse wavelet packet transform as the cleaned data at the fixed frequency. Denote the mean value of all the cleaned data at the fixed frequency as the loosening degree of the terminal block at the fixed frequency.

[0051] In this embodiment, the value of the loosening detection threshold is 0.8. The cleaned data can represent the data excluding the normal vibration and resonance of the joint of the terminal block within the corresponding vibration sequence. The loosening degree of the terminal block at the fixed frequency is used to represent the degree of loosening when the terminal block vibrates at the fixed frequency.

[0052] It can be understood that, according to the same method, the loosening degree of the terminal block at each fixed frequency can be obtained.

[0053] Perform linear fitting on the fixed frequency and the loosening degree of the terminal block at the fixed frequency to obtain the slope of the fitting line. Denote the normalized value of the product of the mean value of the loosening degrees of the terminal block at all fixed frequencies and the slope of the fitting line as the stability detection evaluation value of the terminal block.

[0054] In this embodiment, polynomial fitting technology is used for linear fitting. In the actual application process, as other implementation manners, on the basis of achieving the purpose of linear fitting, the implementer can use other existing technologies such as the least squares method and other methods to perform linear fitting, and this application does not make special restrictions.

[0055] It should be noted that in this embodiment, the Z-Score standard normalization method is used to calculate the normalized value. In the actual application process, the implementer can use other existing technologies such as the maximum-minimum normalization method, sigmoid function, and other methods to calculate the normalized value, which is not limited here.

[0056] The stability detection evaluation value of the terminal block is used to evaluate the loosening degree of the terminal block when used at each fixed frequency. When the stability detection evaluation value is larger, the loosening degree of the terminal block during use is larger.

[0057] When the stability detection evaluation value of the terminal block is greater than the stability detection threshold, determine that the terminal block is a defective product; when the stability detection evaluation value of the terminal block is less than or equal to the stability detection threshold, determine that the terminal block is a qualified product.

[0058] In this embodiment, the value of the stability detection threshold is 0.7.

[0059] Thus, the detection of the electrical connection state of the terminal block is realized.

[0060] Based on the same inventive concept as the above method, an embodiment of the present invention further provides a detection system for the electrical connection state of a terminal block, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above methods for detecting the electrical connection state of a terminal block and the system are implemented.

[0061] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting the electrical connection state of a terminal block, characterized in that The method includes the following steps: Under the electrical connection state of the terminal, collect vibration data at a preset number of different fixed frequencies, and obtain the vibration sequence at the same fixed frequency according to the vibration data at the same fixed frequency; For any one fixed frequency, extract the frame signals of the reconstructed signal of the vibration sequence at the fixed frequency, construct the peak histogram and valley histogram of the frame signals, and determine the time-domain consistency of the reconstructed signal according to the similarity between the peak histograms of different frame signals of the reconstructed signal and the similarity between the valley histograms; Determine the main frequency of the reconstructed signal, determine the main frequency concentration degree of the reconstructed signal according to the difference between the frequency with an amplitude greater than 0 and the main frequency in the frequency spectrum diagram of the reconstructed signal, and the difference between the amplitude greater than 0 and the amplitude of the main frequency. Determine the resonance significance degree of the reconstructed signal according to the main frequency of the reconstructed signal, the fixed frequency of the vibration sequence corresponding to the reconstructed signal, and the main frequency concentration degree of the reconstructed signal. Obtain the loosening possibility of the reconstructed signal according to the time-domain consistency and resonance significance degree of the reconstructed signal; Determine the loosening degree of the terminal at the same fixed frequency according to all the reconstructed signals of the vibration sequence at the same fixed frequency, and obtain the detection result of the electrical connection state of the terminal according to the loosening degree of the terminal at all fixed frequencies.

2. The method for detecting the electrical connection state of a terminal according to claim 1, characterized in that, The specific method for extracting the frame signals of the reconstructed signal of the vibration sequence at the fixed frequency, constructing the peak histogram and valley histogram of the frame signals includes: Perform wavelet packet decomposition on the vibration sequence at the fixed frequency to obtain the reconstructed signals of all nodes in the last layer of the wavelet packet of the vibration sequence, and perform frame windowing processing on the reconstructed signals using a Hamming window to obtain the frame signals of the reconstructed signals; Perform smoothing processing on the frame signals, use the signal peak-valley second-order difference recognition algorithm to extract all the peaks and valleys in the smoothed frame signals, and construct the peak histogram of the frame signals with the amplitude of the peaks and the number of occurrences of the peaks as the horizontal and vertical coordinates of the histogram respectively, and construct the valley histogram of the frame signals with the amplitude of the valleys and the number of occurrences of the valleys as the horizontal and vertical coordinates of the histogram respectively.

3. The electrical connection state detection method of a wiring terminal according to claim 1, characterized in that, The method for determining the time-domain consistency of the reconstructed signal is: Denote the Bhattacharyya coefficient between the peak histograms of two different frame signals of the reconstructed signal as the first similarity between the two different frame signals of the reconstructed signal, and denote the mean value of the first similarities of all different frame signals of the reconstructed signal as the peak similarity of the reconstructed signal; Denote the Bhattacharyya coefficient between the valley histograms of two different frame signals of the reconstructed signal as the second similarity between the two different frame signals of the reconstructed signal, and denote the mean value of the second similarities of all different frame signals of the reconstructed signal as the valley similarity of the reconstructed signal; Denote the mean value of the peak similarity and valley similarity of the reconstructed signal as the time-domain consistency of the reconstructed signal.

4. A method for detecting the electrical connection state of a terminal block, according to claim 1, characterized in that The specific method for determining the main frequency of the reconstructed signal includes: Extract the frequency spectrum diagram of the reconstructed signal, and denote the frequency with the largest amplitude in the frequency spectrum diagram of the reconstructed signal as the main frequency of the reconstructed signal.

5. A method for detecting the electrical connection state of a terminal block according to claim 1, characterized in that, The method for determining the main frequency concentration degree of the reconstructed signal is: Among them, represents the main frequency concentration degree of the th reconstructed signal of the vibration sequence with a fixed frequency; represents the amplitude of the main frequency of the th reconstructed signal of the vibration sequence with a fixed frequency; represents the th th amplitude greater than 0 in the spectrogram of the th reconstructed signal of the vibration sequence with a fixed frequency; represents the main frequency of the th reconstructed signal of the vibration sequence with a fixed frequency; The th th frequency with an amplitude greater than 0 in the spectrogram of the th reconstructed signal of the vibration sequence with a fixed frequency; is an adjustment coefficient; represents the number of amplitudes greater than 0 in the spectrogram of the th reconstructed signal of the vibration sequence with a fixed frequency.

6. The electrical connection state detection method of a wiring terminal according to claim 1, characterized in that, The method for determining the resonance significance degree of the reconstructed signal is: The absolute value of the difference between the main frequency of the reconstructed signal and the fixed frequency of the vibration sequence corresponding to the reconstructed signal is denoted as the first difference of the reconstructed signal; the normalized value of the ratio of the main frequency concentration degree of the reconstructed signal to the first difference is denoted as the resonance significance degree of the reconstructed signal.

7. A method for detecting the electrical connection state of a terminal block, according to claim 1, wherein The specific method for obtaining the looseness possibility of the reconstructed signal according to the time-domain consistency and resonance significance degree of the reconstructed signal includes: The reciprocal of the sum value of the time-domain consistency and resonance significance degree of the reconstructed signal is denoted as the looseness eigenvalue of the reconstructed signal, and the normalized value of the looseness eigenvalue of the reconstructed signal is denoted as the looseness possibility of the reconstructed signal.

8. A method for detecting the electrical connection state of a terminal block according to claim 1, characterized in that, The specific method for determining the looseness degree of the terminal at the same fixed frequency according to all the reconstructed signals of the vibration sequence at the same fixed frequency includes: For any fixed frequency, assign a value of 0 to all the nodes corresponding to the reconstructed signals with looseness possibility less than or equal to the looseness detection threshold in the vibration sequence of the fixed frequency, perform inverse wavelet packet transform on all the nodes in the last layer of wavelet packet of the vibration sequence of the fixed frequency, and denote the signal obtained by the inverse wavelet packet transform as the cleaning data of the fixed frequency. The mean value of all the cleaning data of the fixed frequency is denoted as the looseness degree of the terminal at the fixed frequency.

9. A method for detecting the electrical connection state of a terminal block, according to claim 1, characterized in that, The specific method for obtaining the detection result of the electrical connection state of the terminal according to the looseness degree of the terminal at all fixed frequencies includes: Perform linear fitting on the fixed frequency and the looseness degree of the terminal at the fixed frequency to obtain the slope of the fitting straight line, and the normalized value of the product of the mean value of the looseness degree of the terminal at all fixed frequencies and the slope of the fitting straight line is denoted as the stability detection evaluation value of the terminal. When the stability detection evaluation value of the terminal is greater than the stability detection threshold, it is determined that the terminal is a defective product. When the stability detection evaluation value of the terminal is less than or equal to the stability detection threshold, it is determined that the terminal is a qualified product.

10. A wiring terminal electrical connection state detection system, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1-9.

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