Automatic measuring method for diameter of carbon fiber tow based on ultrasonic sensor

Abstract

The application relates to the technical field of ultrasonic measurement, and discloses an automatic carbon fiber tow diameter measurement method based on an ultrasonic sensor, which comprises the following steps: collecting the distances between a to-be-measured point of a carbon fiber tow with a to-be-measured diameter and different ultrasonic sensors and the three-dimensional coordinates of the to-be-measured point, marking a target acquisition time, determining the average distance, the average distance sequence and the three-dimensional coordinate vector of the target acquisition time; determining the spatial offset and the position jitter characteristic value of the target acquisition time; constructing the position jitter characteristic value sequence and the tow diameter instability strength of the target acquisition time; and adjusting the ultrasonic focal point diameter in real time according to the tow diameter instability strength, so as to realize the measurement of the carbon fiber tow diameter. The application aims to improve the stability and authenticity of the carbon fiber tow diameter measurement.

Description

Technical Field

[0001] This application relates to the field of ultrasonic measurement technology, specifically to an automatic measurement method for carbon fiber bundle diameter based on ultrasonic sensors. Background Technology

[0002] Carbon fiber tow diameter refers to the diameter of the wound portion of a carbon fiber tow after it has been wound into a specific shape. The tow diameter provides a basis for tension control, improving its accuracy and stability. Ultrasonic sensors enable non-contact measurement of the carbon fiber tow diameter, avoiding damage to the carbon fiber and meeting the demands for rapid response in dynamic environments.

[0003] When using ultrasound to measure roll diameter, the carbon fiber layup process is driven by the take-up and untake-up of the material and the complex trajectory of the layup head. The filament bundle will generate non-ideal high-frequency vibration and lateral oscillation, which will cause slight changes in the spatial position and orientation of the filament bundle to be measured. This will cause the surface of the filament bundle to shift rapidly relative to the focus of the ultrasonic beam. The measurement point to be measured will continuously deviate from the preset measurement point, resulting in the ultrasonic ranging being affected by non-realistic jump values ​​and noise, which will reduce the stability and accuracy of the roll diameter measurement. Summary of the Invention

[0004] This application provides an automatic measurement method for carbon fiber tow diameter based on ultrasonic sensors to solve the problem of data distortion at measurement points caused by the vibration of carbon fiber tow, resulting in insufficient stability and accuracy of diameter measurement. The specific technical solution adopted is as follows:

[0005] One embodiment of this application provides an automatic measurement method for carbon fiber tow diameter based on an ultrasonic sensor, the method comprising the following steps:

[0006] The method involves collecting the distances between the test points of the carbon fiber bundle to be measured and different ultrasonic sensors, as well as the three-dimensional coordinates of the test points. Any acquisition time is designated as the target acquisition time. The average distance at the target acquisition time is determined, and a sequence of average distances and a three-dimensional coordinate vector for each target acquisition time are constructed. The spatial offset of the target acquisition time is determined, along with the positional jitter characteristic value. A sequence of positional jitter characteristic values ​​for the target acquisition time is constructed based on these values. The diameter instability intensity at the target acquisition time is determined based on the changing trend of the positional jitter characteristic values ​​and the dominant frequency vibration energy within the sequence. The ultrasonic focal diameter is adjusted in real-time according to the diameter instability intensity to achieve the measurement of the carbon fiber bundle diameter.

[0007] Furthermore, the method for obtaining the average distance at the target acquisition time is as follows:

[0008] The average distance between the test point and all ultrasonic sensors at the same acquisition time is recorded as the average distance at the same acquisition time.

[0009] Furthermore, the method for determining the average distance sequence and three-dimensional coordinate vector at the target acquisition time is as follows:

[0010] Arrange the average distances at the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the average distance sequence at the target acquisition time.

[0011] Arrange the three-dimensional coordinates of the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the three-dimensional coordinate vector of the target acquisition time.

[0012] Furthermore, the method for determining the spatial offset at the target acquisition time is as follows:

[0013] Based on the average distance sequence and three-dimensional coordinate vector at the target acquisition time, the optimal estimated coordinates at the target acquisition time are obtained;

[0014] The Euclidean distance between the three-dimensional coordinates of the point to be measured at the target acquisition time and the optimal estimated coordinates is denoted as the spatial offset of the point to be measured at the target acquisition time.

[0015] Furthermore, the specific method for determining the position jitter feature value at the target acquisition time is as follows:

[0016] Based on the difference between the spatial offset of the target acquisition time and all acquisition times before the target acquisition time, the deviation variance of the target acquisition time is determined. The positive correlation between the spatial offset of the target acquisition time and the deviation variance is recorded as the position jitter characteristic value of the target acquisition time.

[0017] Furthermore, the specific methods for determining the deviation variance at the target acquisition time are as follows:

[0018] The variance of the spatial offset at the target acquisition time and all acquisition times prior to the target acquisition time is denoted as the deviation variance at the target acquisition time.

[0019] Furthermore, the method for constructing the position jitter feature value sequence at the target acquisition time is as follows:

[0020] Arrange the position jitter feature values ​​of the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the position jitter feature value sequence of the target acquisition time.

[0021] Furthermore, the method for determining the roll diameter instability strength at the target acquisition moment is as follows:

[0022] Based on the changing trend of the position jitter feature values ​​within the position jitter feature value sequence at the target acquisition time, determine the first cumulative sum at the target acquisition time;

[0023] Based on the position jitter characteristic value sequence of the target at the acquisition time, obtain the main frequency vibration energy at the acquisition time of the target;

[0024] The result of the positive correlation between the first accumulated sum at the target acquisition time and the dominant frequency vibration energy is denoted as the roll diameter instability intensity at the target acquisition time.

[0025] Furthermore, the method for determining the first accumulated sum at the target acquisition time is as follows:

[0026] Linear fitting is performed on all position jitter feature values ​​contained within the position jitter feature value sequence, the target acquisition time, and the time window before the target acquisition time. The slope of the fitted line is obtained. The product of the mean of all position jitter feature values ​​contained within the time window and the slope of the fitted line is recorded as the first product of the time window of the target acquisition time.

[0027] Starting from the target acquisition time, select acquisition times from historical times and obtain the first product of the time windows of the selected acquisition times;

[0028] The sum of the first products of the target acquisition time window and the first products of all selected acquisition time windows is denoted as the first cumulative sum of the target acquisition time.

[0029] Furthermore, the specific method for real-time adjustment of the ultrasonic focal diameter based on the roll diameter instability intensity includes:

[0030] The adjustment diameter at the target acquisition time is calculated using the following formula:

[0031]

[0032] in, The adjustment diameter indicates the time of target acquisition; Indicates the preset initial ultrasonic focal diameter; This indicates the preset attenuation coefficient; Indicates the roll diameter instability intensity at the moment of target acquisition; Represents the natural constant;

[0033] The adjustment diameter at the target acquisition time is used as the adjustment diameter for the next adjacent acquisition time.

[0034] The beneficial effects of this application are:

[0035] This application first determines the spatial offset at the target acquisition time based on the average distance sequence and three-dimensional coordinate vector at the target acquisition time. The spatial offset is the noise and positional displacement caused by the high-frequency vibration or oscillation of the test point of the carbon fiber bundle at the corresponding acquisition time. Combining the dispersion of the distance between the three-dimensional coordinates of the test point at the target acquisition time and before the target acquisition time and the ideal three-dimensional coordinate position, the overall noise risk and uncertainty level of the test point deviating from the preset focus caused by the vibration and oscillation of the carbon fiber bundle during high-speed motion are evaluated, and the positional jitter characteristic value for each acquisition time is obtained. Based on the changing trend and the dominant frequency vibration energy of the positional jitter characteristic value sequence, the measurement of the carbon fiber bundle diameter at the corresponding acquisition time is evaluated. The strength of the instability risk at the acquisition time is determined to establish the instability intensity of the roll diameter at the target acquisition time. The greater the instability intensity, the more intense the high-frequency vibration and oscillation of the carbon fiber bundle, resulting in more significant noise and offset in the measurement of the carbon fiber bundle roll diameter. Finally, the ultrasonic focal diameter is adjusted in real time according to the instability intensity of the roll diameter, and the sound beam coverage is optimized in real time to realize the measurement of the carbon fiber bundle roll diameter. This avoids the measurement point from leaving the sound beam range and significantly reduces distance jump values ​​and noise. It solves the problem of data distortion at the measurement point caused by the vibration of the carbon fiber bundle, which leads to insufficient stability and authenticity of the roll diameter measurement. Furthermore, it eliminates the tension miscompensation caused by inaccurate ultrasonic ranging and improves the measurement accuracy of the carbon fiber bundle roll diameter. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic flowchart of an automatic measurement method for carbon fiber bundle diameter based on an ultrasonic sensor, provided in one embodiment of this application.

[0038] Figure 2 This is a flowchart illustrating the spatial offset acquisition process provided in one embodiment of this application. Detailed Implementation

[0039] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0040] Please see Figure 1The diagram illustrates a flowchart of an automatic carbon fiber tow diameter measurement method based on an ultrasonic sensor, according to an embodiment of this application. The method includes the following steps:

[0041] Step S001: Collect the distance between the test point of the carbon fiber bundle to be measured and different ultrasonic sensors, as well as the three-dimensional coordinates of the test point. Record any acquisition time as the target acquisition time. Based on the three-dimensional coordinates and distance, determine the average distance of the target acquisition time, and construct the average distance sequence and three-dimensional coordinate vector of the target acquisition time.

[0042] Four ultrasonic sensors are installed above the test area of ​​the carbon fiber bundle whose diameter is to be measured, ensuring that the installation positions of the four ultrasonic sensors are not coplanar. The ultrasonic sensors are used to collect the three-dimensional coordinates of the test point of the carbon fiber bundle whose diameter is to be measured in the test area, as well as the distance between the test point and the ultrasonic sensor.

[0043] Preferably, in one embodiment of this application, the data sampling frequency is set to 100Hz when acquiring three-dimensional coordinates and distances. In practical applications, as other implementation methods, the implementer can determine the sampling frequency according to the actual situation, and this application does not impose any special restrictions.

[0044] The average distance between the test point and all ultrasonic sensors at the same acquisition time is recorded as the average distance at the same acquisition time.

[0045] Record any acquisition time as the target acquisition time. Arrange the average distances of the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the average distance sequence of the target acquisition time. Arrange the three-dimensional coordinates of the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the three-dimensional coordinate vector of the target acquisition time.

[0046] The same method can be used to obtain the average distance sequence and three-dimensional coordinate vector at any acquisition time.

[0047] At this point, the average distance sequence and three-dimensional coordinate vector for each acquisition moment are obtained.

[0048] Step S002: Based on the average distance sequence and three-dimensional coordinate vector of the target acquisition time, determine the spatial offset of the target acquisition time. Based on the difference between the spatial offsets of the target acquisition time and all acquisition times before the target acquisition time, determine the position jitter characteristic value of the target acquisition time.

[0049] During high-speed carbon fiber tow placement, the complex trajectory of the feeding drive and the tow placement head causes coupled non-ideal high-frequency vibrations and lateral oscillations in the carbon fiber tow placement. This results in a significant deviation between the actual motion trajectory of the carbon fiber tow and the ideal motion trajectory. Furthermore, this causes the measurement point of the ultrasonic sensor to continuously deviate from the preset measurement point, resulting in jump noise in the measured value of the carbon fiber roll diameter. This leads to insufficient stability and accuracy in the roll diameter measurement. At the same time, the jump noise directly undermines the stability of the tension control system, causing the tension control system to misjudge changes in the carbon fiber tow roll diameter and issue incorrect tension adjustment commands. This results in drastic fluctuations in the actual tension of the carbon fiber tow and a decrease in quality.

[0050] The spatial offset of the target at the time of acquisition is determined based on the average distance sequence and three-dimensional coordinate vector at the target acquisition time.

[0051] Preferably, as an embodiment of this application, the average distance sequence and three-dimensional coordinate vector at the target acquisition time are input into the Kalman filter algorithm. The state vector is set as position, velocity, and acceleration. A complete dynamic model of the filament spatial motion is constructed through Kalman filtering, and collaborative acquisition is achieved through recursive calculation. The covariance of the observation noise is set to 0.1. The optimal estimated coordinates of the test point at the target acquisition time are obtained using the Kalman filter algorithm. The Euclidean distance between the three-dimensional coordinates of the test point at the target acquisition time and the optimal estimated coordinates is denoted as the spatial offset of the test point at the target acquisition time.

[0052] Understandably, the optimal estimated coordinates are the ideal spatial positions of the measured points of the carbon fiber bundle with the diameter to be measured at the corresponding acquisition time after eliminating jump noise. The larger the spatial offset, the more significant the noise and positional shift caused by high-frequency vibration or oscillation of the measured points of the carbon fiber bundle at the corresponding acquisition time. The flowchart for obtaining the spatial offset is as follows: Figure 2 As shown.

[0053] The position jitter characteristic value at the target acquisition time is determined based on the difference between the spatial offset at the target acquisition time and all acquisition times prior to the target acquisition time.

[0054] Preferably, as an embodiment of this application, the variance of the spatial offset of the target acquisition time and all acquisition times before the target acquisition time is recorded as the deviation variance of the target acquisition time, and the positive correlation processing result of the spatial offset of the target acquisition time and the deviation variance is recorded as the position jitter feature value of the target acquisition time.

[0055] It is understood that a positive correlation processing is applied to the spatial offset and deviation variance at the target acquisition time, ensuring that the spatial offset and deviation variance are positively correlated with the position jitter characteristic value at the target acquisition time. It is understood that the positive correlation in this application refers to the relationship between the independent and dependent variables, where the independent variables are the spatial offset and deviation variance at the target acquisition time, and the dependent variable is the position jitter characteristic value at the target acquisition time. The positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive or multiplicative relationship.

[0056] Preferably, as an embodiment of this application, the product of the spatial offset and the deviation variance at the target acquisition time is recorded as the position jitter feature value at the target acquisition time.

[0057] It is understandable that the deviation variance at the target acquisition time represents the degree of dispersion of the distance between the three-dimensional coordinates of the test point and the ideal three-dimensional coordinate position at and before the target acquisition time. The position jitter characteristic value at the target acquisition time is used to evaluate the overall noise risk and uncertainty level of the test point deviating from the preset focus caused by the vibration and swaying of the carbon fiber bundle during high-speed motion. The larger the position jitter characteristic value, the more violent the vibration and swaying of the bundle during the winding and unwinding process, and the more unstable the test point is.

[0058] The same method can be used to obtain the position jitter feature value at any acquisition time.

[0059] At this point, the position jitter feature value at each acquisition moment is obtained.

[0060] Step S003: Construct a sequence of position jitter feature values ​​for the target acquisition time based on the position jitter feature values. Determine the roll diameter instability intensity at the target acquisition time based on the changing trend of the position jitter feature values ​​within the sequence and the dominant frequency vibration energy of the position jitter feature value sequence.

[0061] When the position jitter characteristic value changes abruptly at each acquisition moment, the tension control system will excessively adjust the control gain to suppress noise, leading to tension instability. When the position jitter characteristic value fluctuates at each acquisition moment, it will cause repeated oscillations and adjustments in the tension control system. At the same time, the changing trend of the position jitter characteristic value will also lead to long-term fatigue feedback in the tension control system, causing fatigue wear.

[0062] Arrange the position jitter feature values ​​of the target acquisition time and all acquisition times before the target acquisition time in chronological order to obtain the position jitter feature value sequence of the target acquisition time.

[0063] Based on the changing trend of the position jitter feature value within the position jitter feature value sequence at the target acquisition time, the first cumulative sum at the target acquisition time is determined.

[0064] Linear fitting is performed on all position jitter feature values ​​contained within the target acquisition time and the first preset time window before the target acquisition time within the position jitter feature value sequence. The slope of the fitted line is obtained. The product of the mean of all position jitter feature values ​​contained within the time window and the slope of the fitted line is recorded as the first product of the time window of the target acquisition time. Starting from the target acquisition time, an acquisition time is selected at intervals of the second preset time from the historical time, and the first product of the time window of the selected acquisition time is obtained. The sum of the first products of the time windows of all selected acquisition times and the target acquisition time is recorded as the first cumulative sum of the target acquisition time.

[0065] Wherein, the first preset duration and the second preset duration are both preset durations. In this embodiment, the first preset duration is set to 50ms and the second preset duration is set to 10ms.

[0066] It is understandable that the first cumulative sum of the target acquisition times is the cumulative intensity evaluation of the combined effect of the deterioration rate and average intensity of the position jitter characteristic value within each sliding window; when the duration corresponding to the acquisition time before the acquisition time is less than the length of a time window, these acquisition times are not analyzed.

[0067] The position jitter feature value sequence at the target acquisition time is processed using the Fast Fourier Transform (FFT) algorithm to obtain the dominant frequency vibration energy at the target acquisition time.

[0068] The use of the Fast Fourier Transform (FFT) algorithm to obtain the dominant frequency vibration energy is a well-known technique and will not be elaborated further. The dominant frequency vibration energy is the energy intensity of the main vibration frequency component of tension instability at the corresponding acquisition time.

[0069] The result of the positive correlation between the first accumulated sum at the target acquisition time and the dominant frequency vibration energy is denoted as the roll diameter instability intensity at the target acquisition time.

[0070] It is understood that the first accumulated sum at the target acquisition time is positively correlated with the dominant frequency vibration energy, that is, the first accumulated sum at the target acquisition time and the dominant frequency vibration energy are respectively positively correlated with the roll diameter instability intensity at the target acquisition time. It is understood that the positive correlation in this application refers to the relationship between the independent variable and the dependent variable, where the independent variables are the first accumulated sum at the target acquisition time and the dominant frequency vibration energy, and the dependent variable is the roll diameter instability intensity at the target acquisition time. The positive correlation means that the dependent variable increases (decreases) as the independent variable increases (decreases), and can be an additive relationship, a multiplicative relationship, etc.

[0071] Preferably, as an embodiment of this application, the product of the first accumulated sum at the target acquisition time and the dominant frequency vibration energy is recorded as the roll diameter instability intensity at the target acquisition time.

[0072] The roll diameter instability strength is used to evaluate the strength of the instability risk in the measurement of carbon fiber bundle roll diameter at the corresponding acquisition time. The greater the roll diameter instability strength, the more violent the high-frequency vibration and oscillation of the carbon fiber bundle, resulting in more significant noise and offset in the measurement of carbon fiber bundle roll diameter.

[0073] The same method can be used to obtain the roll diameter instability intensity at any acquisition time.

[0074] At this point, the roll diameter instability intensity is obtained at each acquisition moment.

[0075] Step S004: Adjust the diameter of the ultrasonic focal point in real time according to the instability strength of the roll diameter to realize the measurement of the carbon fiber bundle roll diameter.

[0076] During the high-speed movement of the carbon fiber bundle, the measurement point will continuously deviate from the preset focal point due to the violent swinging and vibration of the bundle. If a fixed focal diameter is maintained, the measurement point is likely to fall out of the effective coverage of the ultrasonic beam, thus causing inaccurate measurement of the carbon fiber bundle diameter.

[0077] The ultrasonic focal point diameter is dynamically adjusted in real time based on the instability strength of the carbon fiber bundle to obtain the adjustment diameter, ensuring that the measured point remains within the effective detection range during carbon fiber bundle vibration. The formula for calculating the adjustment diameter is:

[0078]

[0079] in, The adjustment diameter indicates the time of target acquisition; This indicates the preset initial ultrasonic focal diameter. The initial ultrasonic focal diameter should be greater than or equal to 5 mm and less than or equal to 12 mm. In this embodiment, the initial ultrasonic focal diameter is set to 6 mm. This represents the preset attenuation coefficient, which controls the focal expansion rate. The value of the attenuation coefficient should be greater than or equal to 0.3 and less than or equal to 0.8. In this embodiment, the value for controlling the focal expansion rate is 0.5. Indicates the roll diameter instability intensity at the moment of target acquisition; Represents the natural constant.

[0080] When the instability intensity of the roll diameter at the moment of target acquisition is greater, a larger adjustment diameter should be selected to expand the ultrasonic coverage area, so that the ultrasonic sensor can tolerate greater spatial offset, avoid the test point from leaving the sound beam range, and significantly reduce distance jump value and noise.

[0081] By using the adjustment diameter at the target acquisition time as the adjustment diameter at the next adjacent acquisition time, automatic measurement of the carbon fiber bundle diameter based on ultrasonic sensors is achieved. The acoustic beam coverage is adjusted and optimized in real time, further eliminating tension miscompensation caused by inaccurate ultrasonic ranging and improving the measurement accuracy of the carbon fiber bundle diameter.

[0082] After the above adjustments, the distance measurements of the four ultrasonic sensors at the same acquisition time and the three-dimensional coordinates of the point to be measured are taken. Based on the installation position and distance measurements of the four sensors, the three-dimensional coordinates of the current carbon fiber bundle point to be measured are updated using a triangulation algorithm. Subsequently, the axis is determined by the empty reel rotation calibration method. Specifically, in the empty reel state without carbon fiber bundles, the reel is controlled to rotate slowly at least one full revolution. During the rotation, the three-dimensional coordinates of 10 reel surface points measured and calculated by the four ultrasonic sensors are recorded at an acquisition frequency of 1kHz, resulting in a set of point cloud data. The least squares method is used to fit the acquired point cloud data to the cylinder to obtain the axis of the fitted cylinder. The Euclidean distance between the three-dimensional coordinates of the point to be measured and the fitted axis is recorded as the diameter of the carbon fiber bundle.

[0083] Among them, updating the three-dimensional coordinates of the test point through triangulation algorithm and fitting the collected point cloud data with the cylinder using the least squares method are well-known techniques and will not be described in detail.

[0084] This achieves automatic measurement of carbon fiber bundle diameter based on ultrasonic sensors.

[0085] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the principles of this application should be included within the protection scope of this application.

Claims

1. A method for automatic measurement of the diameter of a carbon fiber tow roll based on an ultrasonic sensor, characterized by, The method comprises the following steps: The distance between the to-be-measured point of the carbon fiber tow to be measured and different ultrasonic sensors is collected, and the three-dimensional coordinates of the to-be-measured point are collected, any one collection time is recorded as a target collection time, the average distance of the target collection time is determined, and the average distance sequence and the three-dimensional coordinate vector of the target collection time are constructed; the spatial offset of the target collection time is determined, the position jitter characteristic value of the target collection time is determined; the position jitter characteristic value sequence of the target collection time is constructed according to the position jitter characteristic value, the position jitter characteristic value sequence is used to determine the winding diameter instability strength of the target collection time according to the change trend of the position jitter characteristic value in the position jitter characteristic value sequence and the main frequency vibration energy of the position jitter characteristic value sequence; the winding diameter instability strength is used to adjust the ultrasonic focal point diameter in real time, and the measurement of the winding diameter of the carbon fiber tow is realized.

2. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The average distance of the target collection time is obtained by the following method: The average distance of the to-be-measured point at the same collection time and all ultrasonic sensors is recorded as the average distance of the same collection time.

3. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The average distance sequence and the three-dimensional coordinate vector of the target collection time are determined by the following method: The average distance of the target collection time and all collection times before the target collection time are arranged in chronological order to obtain the average distance sequence of the target collection time; The three-dimensional coordinates of the target collection time and all collection times before the target collection time are arranged in chronological order to obtain the three-dimensional coordinate vector of the target collection time.

4. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The spatial offset of the target collection time is determined by the following method: The optimal estimation coordinates of the target collection time are obtained according to the average distance sequence and the three-dimensional coordinate vector of the target collection time; The Euclidean distance between the three-dimensional coordinates of the to-be-measured point at the target collection time and the optimal estimation coordinates is recorded as the spatial offset of the to-be-measured point at the target collection time.

5. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The position jitter characteristic value of the target collection time is determined by the following method: The deviation variance of the target collection time is determined according to the difference between the spatial offsets of the target collection time and all collection times before the target collection time, and the positive correlation processing result of the spatial offset of the target collection time and the deviation variance is recorded as the position jitter characteristic value of the target collection time.

6. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 5, characterized by, The deviation variance of the target collection time is determined by the following method: The variance of the spatial offset of the target collection time and all collection times before the target collection time is recorded as the deviation variance of the target collection time.

7. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The position jitter characteristic value sequence of the target collection time is constructed by the following method: The position jitter characteristic values of the target collection time and all collection times before the target collection time are arranged in chronological order to obtain the position jitter characteristic value sequence of the target collection time.

8. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, wherein, The winding diameter instability strength of the target collection time is determined by the following method: The first cumulative sum of the target collection time is determined according to the change trend of the position jitter characteristic value in the position jitter characteristic value sequence; The main frequency vibration energy of the target collection time is obtained according to the position jitter characteristic value sequence of the target collection time; The positive correlation processing result of the first cumulative sum and the main frequency vibration energy of the target collection time is recorded as the winding diameter instability strength of the target collection time.

9. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 8, characterized by, The determination method of the first accumulation sum of the target acquisition time is: linearly fitting all the position jitter characteristic values in the position jitter characteristic value sequence, the target acquisition time and the time window before the target acquisition time, obtaining the slope of the fitting straight line, multiplying the mean value of all the position jitter characteristic values in the time window by the slope of the fitting straight line, and denoting the product as a first product of the time window of the target acquisition time; selecting an acquisition time from the historical times with the target acquisition time as a starting time, and obtaining the first product of the time window of the selected acquisition time; denoting the accumulation sum of the first products of the time window of the target acquisition time and the time windows of all the selected acquisition times as a first accumulation sum of the target acquisition time.

10. The ultrasonic sensor-based carbon fiber tow roll diameter automatic measurement method according to claim 1, characterized by, The specific method for adjusting the ultrasonic focus diameter in real time according to the roll instability strength comprises: calculating the adjustment diameter of the target acquisition time, and the calculation formula is: wherein, represents an adjusted diameter at a target acquisition time point; represents a preset initial ultrasonic focal point diameter; represents a preset attenuation coefficient; represents a roll diameter instability strength at a target acquisition time point; represents a natural constant; taking the adjustment diameter of the target acquisition time as the adjustment diameter of the next adjacent acquisition time of the target acquisition time.

Images