Wood historical building internal defect detection method based on wood stress wave meter

Abstract

The invention relates to the technical field of data processing, in particular to a wood historical building internal defect detection method based on a wood stress wave meter, which comprises the following steps: acquiring a plurality of times of detection results of a wood historical building, and acquiring a pressure interference factor of each detection result according to pressure data in the detection results; acquiring a humidity accuracy factor of each detection result according to humidity data and stress wave signal propagation speed in the detection results; according to the temperature data in the detection results, obtaining the temperature interference factor of each detection result, combining the pressure interference factor with the humidity accuracy factor, obtaining the deviation degree of the detection results, judging whether the detection results are accurate or not, and correcting the inaccurate detection results. According to the method, interference of external environment factors on detection of the wooden historical building is analyzed from multiple angles, the accuracy of the detection result is judged, and the accurate detection result is corrected, so that the accuracy of detecting the interior of the wooden historical building is improved.

Description

Technical Field

[0001] The invention relates to the technical field of data processing, and in particular to a method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument. Background Art

[0002] As an important part of cultural heritage, wooden historical buildings not only carry rich historical information, but also have unique artistic value and architectural technology. However, as time goes by, wooden historical buildings face many deterioration problems such as aging, decay, and insect pests, which in turn lead to safety hazards of the building structure. Therefore, accurately detecting the defects inside wooden historical buildings and evaluating the structural safety of wood have become important tasks in building maintenance and restoration.

[0003] The wood stress wave meter is a testing tool that evaluates wood quality based on the propagation characteristics of stress waves. The wood stress wave meter determines the type, location and severity of defects inside the wood by stimulating stress waves inside the wood and receiving changes during the propagation of stress waves. The stress wave meter can provide a fast and non-destructive testing method, which is especially suitable for the inspection of wooden buildings; however, when using the wood stress wave meter to test wooden historical buildings, environmental factors will affect the natural properties of the wood, such as humidity and density, and thus affect the propagation of stress waves, resulting in reduced accuracy of the test results. Summary of the invention

[0004] The invention provides a method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument, so as to solve the existing problem that when the wood stress wave instrument is used to detect internal defects of wooden historical buildings, the detection result is affected by the surrounding environment, so that the accuracy of the detection result is reduced.

[0005] The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument of the present invention adopts the following technical solutions: The following steps are involved: Obtaining several test results of wooden historical buildings, wherein the test results include pressure data, humidity data, temperature data, and stress wave signal propagation speed; According to the amplitude and change of the pressure data in the test results, the pressure instability degree of each test result is obtained; according to the pressure instability degree of the test results, the pressure interference factor of each test result is obtained by combining the pressure data in all the test results with the change of the propagation speed of the stress wave signal; According to the humidity data and the propagation speed of the stress wave signal in the test results, the mapped humidity curve and the mapped wave speed curve of each test result are obtained; according to the difference between the mapped humidity curve and the mapped wave speed curve of the test results, the deviation factor of the humidity data and the propagation speed of the stress wave signal in each test result is obtained; according to the deviation factor of the humidity data and the propagation speed of the stress wave signal in the test results, combined with the mapped humidity curve of the test results, the humidity accuracy factor of each test result is obtained; According to the amplitude and change of temperature data in the test results, the temperature interference factor of each test result is obtained; according to the temperature interference factor of the test result, combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result, the deviation degree of each test result is obtained; according to the deviation degree of the test result, whether the test result is accurate is judged, and the stress wave signal of the inaccurate test result is corrected.

[0006] Preferably, the method of obtaining several test results of wooden historical buildings includes: The wood stress wave instrument includes a stress wave generator and a stress wave receiving sensor. The stress wave generator and the stress wave receiving sensor are installed on the surface of the wood to be tested, and a pressure sensor, a humidity sensor, and a temperature sensor are integrated and installed at the stress wave transmitter. The stress wave transmitter is electronically excited to transmit a stress wave signal to the inside of the wood to be tested, and the stress wave receiving sensor receives the stress wave signal to obtain the propagation speed of the stress wave signal, and records the pressure data, humidity data, and temperature data at each moment in the process from stress wave emission to reception, which together constitute a detection result. Preset a detection number , using wood stress wave instrument to obtain Results.

[0007] Preferably, the method of obtaining the pressure instability degree of each test result according to the amplitude and change of the pressure data in the test result includes: Preset an upper pressure threshold With the lower pressure threshold For the The test results will be The ratio between the mean of the maximum values ​​of all pressure data in the first test result and the upper pressure threshold is recorded as The first pressure instability factor of the test result; The ratio between the mean of the minimum values ​​of all pressure data in the first test result and the lower pressure threshold is recorded as The second pressure instability factor of the test result; The difference between the first pressure instability factor and the second pressure instability factor of the first detection result and the normalized result are used as the The degree of pressure instability of the test results.

[0008] Preferably, the pressure disturbance factor of each test result is obtained according to the pressure instability degree of the test result, in combination with the pressure data in all the test results and the change of the propagation speed of the stress wave signal, and the specific method includes: For The test results are obtained according to the Combine all the pressure data and stress wave signal propagation speed in all the test results to obtain the The specific calculation formula of the pressure interference factor of the test result is: In the formula, Indicates Pressure interference factor of the secondary test result; Indicates The degree of pressure instability of the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates the number of test results; It represents the absolute value function; Represents the preset hyperparameters.

[0009] Preferably, the method of obtaining the mapped humidity curve and the mapped wave velocity curve of each test result according to the humidity data and the propagation speed of the stress wave signal in the test result includes the following specific methods: For The test results for the All humidity data and all stress wave signal propagation velocities in the first test result are linearly normalized to obtain all normalized humidity data and all normalized stress wave signal propagation velocities, which are recorded as The mapping humidity and mapping wave speed of the test results are as follows; a mapping space is constructed with time as the horizontal axis, mapping humidity as the left vertical axis, and mapping wave speed as the right vertical axis. The mapped humidity and mapped wave velocity of the first detection result are placed in the mapping space respectively, and the least squares method is used to fit all the mapped humidity and all the mapped wave velocities respectively to obtain the first Mapping humidity curve and mapping wave velocity curve of the test results.

[0010] Preferably, the method of obtaining the deviation factor between the humidity data and the propagation speed of the stress wave signal in each test result according to the difference between the mapped humidity curve and the mapped wave speed curve of the test result includes the following specific methods: The first The data points with the same corresponding time in the mapped humidity curve and the mapped wave velocity curve of the test result are classified into the same data point group. The difference between the mapped humidity and the mapped wave velocity in all data point groups is used to obtain the first The specific calculation formula of the deviation factor between the humidity data and the propagation speed of the stress wave signal in the test result is: In the formula, Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data point groups in the test result; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Represents the absolute value function.

[0011] Preferably, the humidity accuracy factor of each test result is obtained based on the deviation factor between the humidity data in the test result and the propagation speed of the stress wave signal, in combination with the mapped humidity curve of the test result, and the specific method includes: For The test results, according to The mapping curve of the test results is combined with the The deviation factor between the humidity data and the propagation speed of the stress wave signal in the first test result is obtained. The humidity accuracy factor of the test result is calculated by the following formula: In the formula, Indicates The humidity accuracy factor of the test result; Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data points in the mapped humidity curve of the test result; Indicates The mapping humidity curve of the test result The slope of the data point.

[0012] Preferably, the specific method of obtaining the temperature interference factor of each test result according to the amplitude and change of the temperature data in the test result includes: For The test results will be The maximum mean of all temperature data in the test results is recorded as The temperature extreme factor in the test results of the first The variance of all temperature data in the test results is normalized, and the normalized result is recorded as The temperature change factor in the first test result; the product of the temperature change factor and the temperature extreme factor is used as the The temperature interference factor of the test results.

[0013] Preferably, the degree of deviation of each test result is obtained based on the temperature interference factor of the test result, combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result, and the specific calculation formula included is: In the formula, Indicates The degree of bias in the test results; Indicates Pressure interference factor of the secondary test result; Indicates The humidity accuracy factor of the test result; Indicates Temperature interference factor of the test result; Represents an exponential function with a natural constant as base.

[0014] Preferably, judging whether the test result is accurate according to the degree of deviation of the test result and correcting the stress wave signal of the inaccurate test result includes the following specific methods: Preset a deviation threshold ; For any test result, if the deviation of the test result is less than or equal to , then the test result is accurate; if the deviation of the test result is greater than , then the detection result is inaccurate, and the stress wave signal of the detection result is filtered using a Gaussian filter, and the deviation degree of the detection result is used as the filtering weight of the Gaussian filter to correct the stress wave signal of the detection result.

[0015] The beneficial effects of the technical solution of the present invention are as follows: the present invention performs multiple inspections on wooden historical buildings, analyzes each inspection, analyzes the pressure data in each inspection result, and evaluates the influence of the pressure data in each inspection result on the inspection result in combination with the sensitivity of wood to the change in pressure data, thereby obtaining a pressure interference factor of the inspection result; further, by analyzing the relationship between the humidity data and the propagation speed of the stress wave signal in each inspection result, a deviation factor between the humidity data and the propagation speed of the stress wave signal in the inspection result is obtained, and in combination with the stability of the ambient humidity, a humidity accuracy factor of the inspection result is obtained; since the propagation speed of the stress wave is negatively correlated with the humidity, and the more stable the external humidity is, the more accurate the inspection result is, therefore, by analyzing the negative correlation between the external humidity and the propagation speed of the stress wave in the result, the accuracy of the inspection result is evaluated in combination with the stability of the external humidity; further, by analyzing the amplitude and change of the external temperature, a temperature interference factor of the inspection result is obtained.

[0016] Finally, according to the temperature interference factor of the test result, combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result, the deviation degree of the test result is obtained; through multi-dimensional analysis, when using the wood stress wave instrument to detect internal defects of wooden historical buildings, the influence of various environmental factors on the test results is analyzed and calculated, the deviation degree of the test result is analyzed and calculated, the accuracy of the test result is judged by the deviation degree of the test result, and the inaccurate stress wave signal of the test result is further corrected, so as to accurately obtain the internal information characteristics of wooden historical buildings and avoid external interference. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a flowchart of the steps of the method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument of the present invention; Figure 2 Flowchart for obtaining the degree of deviation of test results. DETAILED DESCRIPTION

[0019] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of the specific implementation method, structure, features and effects of the internal defect detection method of wooden historical buildings based on a wood stress wave instrument proposed by the present invention in combination with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0020] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0021] The specific scheme of the internal defect detection method of wooden historical buildings based on the wood stress wave instrument provided by the present invention is described in detail below with reference to the accompanying drawings.

[0022] See also Figure 1 , which shows a flowchart of a method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument provided by an embodiment of the present invention, the method comprising the following steps: Step S001: obtaining several test results of wooden historical buildings, wherein the test results include pressure data, humidity data, temperature data and stress wave signal propagation speed.

[0023] It should be noted that the wood stress wave meter is a detection tool that evaluates the quality of wood based on the propagation characteristics of stress waves. The wood stress wave meter determines the type, location and severity of defects inside the wood by exciting stress waves inside the wood and receiving changes during the propagation of stress waves. The stress wave meter can provide a fast and non-destructive detection method, which is particularly suitable for the inspection of wooden buildings; but the natural properties of wood such as moisture, density, and texture will affect the propagation of stress waves, resulting in reduced accuracy of the detection results. Therefore, this embodiment proposes a method for detecting internal defects of wooden historical buildings based on a wood stress wave meter, which combines and analyzes the influence of pressure, humidity, and temperature factors when collecting stress waves to determine whether the stress waves collected by the wood stress wave meter are accurate, and further corrects the stress waves collected by the wood stress wave meter.

[0024] Specifically, the wood stress wave instrument includes a stress wave generator and a stress wave receiving sensor. The stress wave generator and the stress wave receiving sensor are installed on the surface of the wood to be tested, and a pressure sensor, a humidity sensor, and a temperature sensor are integrated and installed at the stress wave transmitter; the stress wave transmitter is electronically excited to transmit a stress wave signal to the inside of the wood to be tested, and the stress wave receiving sensor receives the stress wave signal to obtain the propagation speed of the stress wave signal, and records the pressure data, humidity data, and temperature data at each moment in the process from the stress wave emission to the reception, which together constitute a detection result. In this embodiment, 0.1 second is used as a moment, and in the process of any detection result, the stress wave signal propagation speed, pressure data, humidity data, and temperature data are obtained every 0.1 second; Preset a detection number , The specific value of can be set according to the actual situation. This embodiment does not make a hard requirement. Describe, using wood stress wave instrument to obtain Results.

[0025] So far, several test results have been obtained.

[0026] Step S002: Obtain the pressure instability of each test result based on the amplitude and change of the pressure data in the test results; obtain the pressure interference factor of each test result based on the pressure instability of the test results, combined with the pressure data in all test results and the change of the stress wave signal propagation speed.

[0027] It should be noted that in the process of defect detection inside wooden historical buildings based on the wood stress wave meter, if the pressure between the wood stress wave meter and the wood to be detected is too low, the stress wave signal will not be able to effectively propagate into the wood, causing the stress wave signal to decay quickly, and thus the defects inside the wood cannot be accurately detected; if the pressure between the wood stress wave meter and the wood to be detected is too high, it will cause local deformation on the surface of the wood to be tested, thereby affecting the transmission of the stress wave signal in the wood to be tested, resulting in unstable propagation speed of the stress wave signal, and also unable to accurately detect defects inside the wood; therefore, the present invention analyzes the stability of the collected stress wave signal by combining the corresponding pressure data when collecting the stress wave signal, which is more conducive to the subsequent judgment of whether the stress wave collected by the wood stress wave meter is accurate.

[0028] Preferably, in a specific embodiment of the present invention, a pressure upper limit threshold is preset With the lower pressure threshold , and The specific values ​​of can be set according to the actual situation. This embodiment does not make a rigid requirement. In this embodiment, Pascal, Pascal is used as an example; for the The test results will be The ratio between the mean of the maximum values ​​of all pressure data in the first test result and the upper pressure threshold is recorded as The first pressure instability factor of the test result; The ratio between the mean of the minimum values ​​of all pressure data in the first test result and the lower pressure threshold is recorded as The second pressure instability factor of the test result; The difference between the first pressure instability factor and the second pressure instability factor of the first detection result and the normalized result are used as the The pressure instability degree of each test result is measured; wherein the normalization method adopts linear normalization, and the normalization object is the difference between the first pressure instability factor and the second pressure instability factor of all test results.

[0029] It should be noted that the larger the ratio between the mean of all maximum values ​​and the upper pressure threshold, or the smaller the ratio between the mean of all minimum values ​​and the lower pressure threshold, the less the pressure between the stress wave instrument and the wood is within the normal range, the less accurate the obtained stress wave signal is, and the more it is necessary to correct the stress wave signal later.

[0030] It should be further explained that the pressure between the wood stress wave instrument and the wood to be tested will affect the propagation speed of the stress wave signal in the wood to be tested, and the change in propagation speed caused by the pressure between the wood stress wave instrument and the wood to be tested is related to the type of wood, that is, the propagation speed of stress waves in different woods and the sensitivity to the pressure between the wood stress wave instrument and the wood to be tested are different; for example, the propagation speed of stress waves in pine wood is sensitive to changes in contact pressure; while the propagation speed of stress waves in walnut wood is not sensitive to changes in contact pressure; in order to more accurately obtain the influence of the pressure between the wood stress wave instrument and the wood to be tested on the stress wave data, it is necessary to obtain the pressure interference factor based on the degree of pressure instability combined with the degree of wood force sensitivity.

[0031] Preferably, in a specific embodiment of the present invention, for The test results are obtained according to the Combine all the pressure data and stress wave signal propagation speed in all the test results to obtain the The specific calculation formula of the pressure interference factor of the test result is: In the formula, Indicates Pressure interference factor of the secondary test result; Indicates The degree of pressure instability of the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates the number of test results; It represents the absolute value function; represents the preset hyperparameters, The specific value of can be set according to the actual situation. This embodiment does not make a hard requirement. Narrate, set The purpose is to avoid This results in the formula output being 0.

[0032] It should be noted that It represents the change in pressure data fluctuation between two adjacent test results; It represents the change in the fluctuation of the propagation velocity of the stress wave signal in two adjacent overall test results; The smaller the value is, the more the fluctuation of the propagation speed of the stress wave signal will change with the change of the pressure data. At this time, if the pressure between the stress wave instrument and the wood is not within the normal range, it will seriously affect the accuracy of the test results. That is, the greater the impact of the pressure between the stress wave instrument and the wood on the test results, the more inaccurate the test results will be, and the more they need to be corrected.

[0033] At this point, the pressure interference factor of the test result is obtained.

[0034] Step S003: According to the humidity data and the propagation speed of the stress wave signal in the test results, obtain the mapping humidity curve and the mapping wave speed curve of each test result; according to the difference between the mapping humidity curve and the mapping wave speed curve of the test results, obtain the deviation factor of the humidity data and the propagation speed of the stress wave signal in each test result; according to the deviation factor of the humidity data and the propagation speed of the stress wave signal in the test results, combined with the mapping humidity curve of the test results, obtain the humidity accuracy factor of each test result.

[0035] Wooden historical buildings will absorb moisture from the external environment, and the moisture absorbed into the wooden historical buildings will increase the density and viscosity of the wooden materials, thereby reducing the propagation speed of stress waves in the wooden materials, resulting in inaccurate detection results of the wood stress wave instrument. Therefore, it is necessary to correct the detection results of the wood stress wave instrument based on the humidity data collected during the detection process to avoid the influence of humidity in the external environment on the detection results of the stress wave.

[0036] Preferably, in a specific embodiment of the present invention, for The test results for the All humidity data and all stress wave signal propagation velocities in the first test result are linearly normalized to obtain all normalized humidity data and all normalized stress wave signal propagation velocities, which are recorded as The mapping humidity and mapping wave velocity of the test results are constructed; with time as the horizontal axis and 0 to 1 as the vertical axis, a mapping space is constructed, with the mapping humidity as the left vertical axis and the mapping wave velocity as the right vertical axis. Due to normalization, the interval range of the left and right vertical axes is the same; The mapped humidity and mapped wave velocity of the first detection result are placed in the mapping space respectively, and the least squares method is used to fit all the mapped humidity and all the mapped wave velocities respectively to obtain the first The mapping humidity curve and the mapping wave velocity curve of the detection result are as follows; since the least square method is a well-known prior art, it will not be described in detail in this embodiment.

[0037] Furthermore, The data points with the same corresponding time in the mapped humidity curve and the mapped wave velocity curve of the test result are classified into the same data point group. The difference between the mapped humidity and the mapped wave velocity in all data point groups is used to obtain the first The specific calculation formula of the deviation factor between the humidity data and the propagation speed of the stress wave signal in the test result is: In the formula, Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data point groups in the test result; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Represents the absolute value function.

[0038] It should be noted that The larger the value is, the more negatively correlated the stress wave signal propagation velocity change area is with the edge trend of humidity; that is, when the humidity is on an upward trend, the propagation velocity of the stress wave signal is on a decaying trend. At the same time, it means that the stress wave signal at this time is more in line with the propagation form under the objective humidity conditions, that is, the stress wave signal under this detection result is more accurate.

[0039] It should be further explained that in an environment with unstable humidity, the moisture content of wood will change with the change of air humidity, resulting in instability of wood density and elastic modulus, which directly affects the propagation speed and propagation path of stress wave signals in wood, and ultimately causes fluctuations in the propagation speed and frequency of stress wave signals, reducing the accuracy of the test results. Therefore, it is necessary to further combine the stability of humidity during the test process to obtain the humidity accuracy factor of the test results, which is conducive to the subsequent judgment of whether the stress wave collected by the wood stress wave instrument is accurate.

[0040] Furthermore, for the The test results, according to The mapping curve of the test results is combined with the The deviation factor between the humidity data and the propagation speed of the stress wave signal in the first test result is obtained. The humidity accuracy factor of the test result is calculated by the following formula: In the formula, Indicates The humidity accuracy factor of the test result; Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data points in the mapped humidity curve of the test result; Indicates The mapping humidity curve of the test result The slope of the data point is obtained by mapping the humidity curve.

[0041] It should be noted that The larger the value, the The more the stress wave signal in the test result conforms to the propagation form under the objective humidity conditions, the more accurate the stress wave signal in the test result is; The smaller the value, the more During the test, the more stable the humidity of the external environment is, the more stable the density and elastic modulus of the wood will be, and the less likely it will interfere with the propagation of stress wave signals in the wood. The larger the value of The more accurate the test results.

[0042] At this point, the humidity accuracy factor of each test result is obtained.

[0043] Step S004: Obtain the temperature interference factor of each test result based on the amplitude and change of the temperature data in the test result; obtain the degree of deviation of each test result based on the temperature interference factor of the test result, combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result; determine whether the test result is accurate based on the degree of deviation of the test result, and correct the stress wave signal of the inaccurate test result.

[0044] It should be noted that the wooden materials in wooden historical buildings will expand due to heat. The expanded wooden materials under extreme temperature conditions will seriously affect the propagation speed of stress waves in the wooden materials, resulting in inaccurate detection results of the wood stress wave instrument. Therefore, it is necessary to correct the detection results of the wood stress wave instrument based on the temperature data collected during the detection process to avoid the influence of the temperature in the external environment on the detection results of the stress wave.

[0045] Preferably, in a specific embodiment of the present invention, for The test results will be The maximum mean of all temperature data in the test results is recorded as The temperature extreme factor in the test results of the first The variance of all temperature data in the test results is normalized, and the normalized result is recorded as The temperature change factor in the test result is normalized by a sigmoid function; the product of the temperature change factor and the temperature extreme factor is used as the The temperature interference factor of the test results.

[0046] It should be noted that the larger the temperature extreme factor is, the higher the temperature is, the greater the impact on the propagation of stress waves in the wood material will be, and the larger the temperature change factor is, the greater the temperature change is, that is, the more likely it is that extreme temperatures will occur, and the calculated temperature conditions will interfere with the propagation of stress waves in the wood material; therefore, the larger the temperature interference factor of the test result is, the less accurate the test result is, and the accuracy of the test result is obtained by further combining the pressure interference factor and the humidity accuracy factor of the test result obtained in step S002 and step S003.

[0047] Preferably, in a specific embodiment of the present invention, for The test results, according to The pressure interference factor, humidity accuracy factor and temperature interference factor of the test results are obtained. The specific calculation formula for the accuracy of the test results is: In the formula, Indicates The degree of bias in the test results; Indicates Pressure interference factor of the secondary test result; Indicates Humidity accuracy factor for each test result; Indicates Temperature interference factor of the test result; represents an exponential function with a natural constant as the base. In this embodiment, Model to present inverse proportional relationship and normalization, As the input of the model, the implementer can set the inverse proportional function and normalization function according to the actual situation.

[0048] The flowchart of obtaining the deviation degree of the detection result in this embodiment is as follows Figure 2 As shown, Figure 2 Flowchart for obtaining the degree of deviation of test results.

[0049] When explanation is needed, The value of is large, indicating that the use of wood stress wave instrument for the first During the first test, the external humidity interference is small and the pressure between the wood stress wave instrument and the surface of the wood to be tested is appropriate, so the first The test results are accurate. The larger the The more extreme the external environment temperature is during the test, the more it will affect the test and the accuracy of the test result. Model pair The inverse proportional relationship and normalization processing are performed to obtain the deviation degree of the test result. Further, the accuracy of the test result can be judged according to the deviation degree of the test result, and the inaccurate stress wave signal can be corrected based on this.

[0050] Specifically, a deviation threshold is preset , The specific value of can be set according to the actual situation. This embodiment does not make a hard requirement. For any test result, if the deviation of the test result is less than or equal to , then the test result is accurate; if the deviation of the test result is greater than , then the detection result is inaccurate, and the stress wave signal of the detection result needs to be corrected. The stress wave signal of the detection result is filtered using a Gaussian filter, and the deviation degree of the detection result is used as the filtering weight of the Gaussian filter to correct the stress wave signal of the detection result. Since the Gaussian filter is a well-known prior art, it will not be described in detail in this embodiment.

[0051] It should be noted that this embodiment uses a wood stress wave instrument to detect internal defects of wooden historical buildings through multi-dimensional analysis, and analyzes the impact of various environmental factors on the detection results, analyzes and calculates the degree of deviation of the detection results, judges the accuracy of the detection results by the degree of deviation of the detection results, and further corrects the inaccurate stress wave signal of the detection result, so as to accurately obtain the internal information characteristics of the wooden historical buildings and avoid external interference.

[0052] At this point, this embodiment is completed.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument, characterized in that: The method comprises the following steps: Obtaining several test results of wooden historical buildings, wherein the test results include pressure data, humidity data, temperature data, and stress wave signal propagation speed; According to the amplitude and change of the pressure data in the test results, the pressure instability degree of each test result is obtained; according to the pressure instability degree of the test results, the pressure interference factor of each test result is obtained by combining the pressure data in all the test results with the change of the propagation speed of the stress wave signal; According to the humidity data and the propagation speed of the stress wave signal in the test results, the mapped humidity curve and the mapped wave speed curve of each test result are obtained; according to the difference between the mapped humidity curve and the mapped wave speed curve of the test results, the deviation factor of the humidity data and the propagation speed of the stress wave signal in each test result is obtained; according to the deviation factor of the humidity data and the propagation speed of the stress wave signal in the test results, combined with the mapped humidity curve of the test results, the humidity accuracy factor of each test result is obtained; According to the amplitude and change of temperature data in the test results, the temperature interference factor of each test result is obtained; according to the temperature interference factor of the test result, combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result, the deviation degree of each test result is obtained; according to the deviation degree of the test result, whether the test result is accurate is judged, and the stress wave signal of the inaccurate test result is corrected.

2. According to claim 1, the method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument is characterized in that: The specific method of obtaining several test results of wooden historical buildings includes: The wood stress wave instrument includes a stress wave generator and a stress wave receiving sensor. The stress wave generator and the stress wave receiving sensor are installed on the surface of the wood to be tested, and a pressure sensor, a humidity sensor, and a temperature sensor are integrated and installed at the stress wave transmitter. The stress wave transmitter is electronically excited to transmit a stress wave signal to the inside of the wood to be tested, and the stress wave receiving sensor receives the stress wave signal to obtain the propagation speed of the stress wave signal, and records the pressure data, humidity data, and temperature data at each moment in the process from stress wave emission to reception, which together constitute a detection result. Preset a detection number , using wood stress wave instrument to obtain Results.

3. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1 is characterized in that: The specific method of obtaining the pressure instability degree of each test result according to the amplitude and change of the pressure data in the test result is as follows: Preset an upper pressure threshold With lower pressure threshold For the The test results will be The ratio between the mean of the maximum values ​​of all pressure data in the first test result and the upper pressure threshold is recorded as The first pressure instability factor of the test result; The ratio between the mean of the minimum values ​​of all pressure data in the first test result and the lower pressure threshold is recorded as The second pressure instability factor of the test result; The difference between the first pressure instability factor and the second pressure instability factor of the first detection result and the normalized result are used as the The degree of pressure instability of the test results.

4. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The pressure disturbance factor of each test result is obtained according to the pressure instability degree of the test result, combining the pressure data in all the test results with the change of the propagation speed of the stress wave signal, and the specific method includes: For The test results are obtained according to the Combine all the pressure data and stress wave signal propagation speed in all the test results to obtain the The specific calculation formula of the pressure interference factor of the test result is: In the formula, Indicates Pressure interference factor of the secondary test result; Indicates The degree of pressure instability of the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of all pressure data in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates The standard deviation of the propagation speed of all stress wave signals in the test results; Indicates the number of test results; It represents the absolute value function; Represents the preset hyperparameters.

5. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The specific method of obtaining the mapped humidity curve and the mapped wave velocity curve of each test result according to the humidity data and the propagation speed of the stress wave signal in the test result is as follows: For The test results for the All humidity data and all stress wave signal propagation velocities in the first test result are linearly normalized to obtain all normalized humidity data and all normalized stress wave signal propagation velocities, which are recorded as Mapped humidity and mapped wave velocity of the test results; A mapping space is constructed with time as the horizontal axis, humidity as the left vertical axis, and wave velocity as the right vertical axis. The mapped humidity and mapped wave velocity of the first detection result are placed in the mapping space respectively, and the least squares method is used to fit all the mapped humidity and all the mapped wave velocities respectively to obtain the first Mapping humidity curve and mapping wave velocity curve of the test results.

6. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The specific method of obtaining the deviation factor between the humidity data and the propagation speed of the stress wave signal in each test result according to the difference between the mapped humidity curve and the mapped wave speed curve of the test result is as follows: The first The data points with the same corresponding time in the mapped humidity curve and the mapped wave velocity curve of the test results are grouped into the same data point group. The difference between the mapped humidity and the mapped wave velocity in all data point groups is used to obtain the first The specific calculation formula of the deviation factor between the humidity data and the propagation speed of the stress wave signal in the test result is: In the formula, Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data point groups in the test result; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Indicates The test results of the amplitude of the data points in the mapped humidity curve in the data point group; Indicates The test results of The amplitude of the data points in the mapped wave velocity curve in the data point group; Represents the absolute value function.

7. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The specific method of obtaining the humidity accuracy factor of each test result based on the deviation factor of the humidity data and the propagation speed of the stress wave signal in the test result and the mapped humidity curve of the test result is as follows: For The test results, according to The mapping curve of the test results is combined with the The deviation factor between the humidity data and the propagation speed of the stress wave signal in the first test result is obtained. The humidity accuracy factor of the test result is calculated by the following formula: In the formula, Indicates The humidity accuracy factor of the test result; Indicates The deviation factor between the humidity data and the propagation speed of the stress wave signal in the test results; Indicates The number of data points in the mapped humidity curve of the test result; Indicates The mapping humidity curve of the test result The slope of the data point.

8. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The specific method of obtaining the temperature interference factor of each test result according to the amplitude and change of the temperature data in the test result is as follows: For The test results will be The maximum mean of all temperature data in the test results is recorded as Temperature extreme factors in the test results; For The variance of all temperature data in the test results is normalized, and the normalized result is recorded as Temperature variation factor in the test results; The product of the temperature change factor and the temperature extreme factor is taken as the first The temperature interference factor of the test results.

9. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The temperature interference factor of the test result is combined with the pressure interference factor of the test result and the humidity accuracy factor of the test result to obtain the degree of deviation of each test result, including the specific calculation formula: In the formula, Indicates The degree of bias in the test results; Indicates Pressure interference factor of the secondary test result; Indicates The humidity accuracy factor of the test result; Indicates Temperature interference factor of the test result; Represents an exponential function with a natural constant as base.

10. The method for detecting internal defects of wooden historical buildings based on a wood stress wave instrument according to claim 1, characterized in that: The method of judging whether the test result is accurate according to the degree of deviation of the test result and correcting the stress wave signal of the inaccurate test result includes the following specific methods: Preset a deviation threshold ; For any test result, if the deviation of the test result is less than or equal to , then the test result is accurate; if the deviation of the test result is greater than , then the detection result is inaccurate, and the stress wave signal of the detection result is filtered using a Gaussian filter, and the deviation degree of the detection result is used as the filtering weight of the Gaussian filter to correct the stress wave signal of the detection result.

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