Air-jet loom yarn vibration tension test experiment method and system

Abstract

This invention proposes an experimental method and system for testing the vibration tension of yarn in an air-jet loom. The method includes: constructing a yarn tension testing platform and collecting acceleration signals from each vibration source during the loom's operation; calculating the weighting coefficients of each vibration source at the yarn contact support point using OPAX vibration transmission path analysis based on the reference acceleration signals of each vibration source and the response signals at the yarn response points; weighting and synthesizing the acceleration signals of each vibration source with their corresponding weighting coefficients to obtain a multi-excitation joint input signal; loading the multi-excitation joint input signal onto a controllable vibration table; acquiring a sequence of vibration images of the yarn, extracting yarn fluctuation characteristics based on image processing algorithms, and inverting the dynamic tension changes of the yarn; decoupling and studying the weighting coefficients of each vibration source on the dynamic tension fluctuations of the yarn to clarify the mapping relationship between the vibration source and the yarn tension; this method achieves quantitative analysis and decoupling analysis of the contribution of each vibration source, improving the accuracy and research efficiency of yarn dynamic tension testing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air-jet looms, in particular to an air-jet loom yarn vibration tension test experiment method and system. BACKGROUND

[0002] Yarn tension is one of the most critical technical parameters in the weaving process, and its stability directly determines the quality of the fabric. Excessive tension can increase the yarn breakage rate and damage the strength. Insufficient tension can cause unclear selvedges, increased weft stoppages, and deteriorated fabric style. Therefore, accurate and reliable testing and control of yarn tension is a core link for improving the production efficiency and product quality of textile enterprises. In the actual weaving environment, the yarn is in an extremely complex dynamic vibration working condition. The tension fluctuation is not only caused by the mechanical movement of the warp feeding and take-up system, but also strongly affected by the coupling excitation of multiple vibration sources such as beating impact, heald frame movement, and main shaft rotation. These vibrations are transmitted to the yarn path through the mechanical structure, inducing complex transverse fluctuations. There is a strong coupling relationship between this fluctuation and the static tension.

[0003] Traditional testing methods fail to fully consider the comprehensive influence of the coupling excitation of multiple vibration sources on the dynamic tension of the yarn, making it difficult to accurately reflect the real stress state of the yarn in the actual high-speed weaving environment. At the same time, the existing technology lacks an effective way to reproduce this complex vibration working condition in a real controlled experimental environment, and cannot independently analyze and decouple the contribution of the vibration sources, reducing the accuracy and research efficiency of the yarn dynamic tension test. SUMMARY

[0004] Therefore, the present application provides an air-jet loom yarn vibration tension test experiment method and system, which solves the problem of inaccurate test results caused by ignoring the coupling excitation of multiple vibration sources in traditional testing methods. It also realizes quantitative analysis and decoupling analysis of the contribution of each vibration source, improving the accuracy and research efficiency of the yarn dynamic tension test.

[0005] The technical solution of the present application is as follows: In a first aspect, the present application provides an air-jet loom yarn vibration tension test experiment method, comprising the following steps:

[0006] S1, a yarn tension test experiment platform is built, which includes a controllable vibration table and a yarn tension test module installed thereon;

[0007] S2, identify the vibration sources and their distribution positions in the operation of the loom, arrange acceleration sensors at each vibration source, and collect the acceleration signals of each vibration source under the working state of the loom;

[0008] S3, based on the reference acceleration signal of each vibration source and the response signal of the yarn response point, calculate the weight coefficient of each vibration source to the yarn contact support through OPAX vibration transmission path analysis, and weight and synthesize the acceleration signal of each vibration source with the corresponding weight coefficient to obtain the multi-excitation joint input signal;

[0009] S4 applies a multi-excitation combined input signal to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom;

[0010] S5: Acquire a sequence of vibration images of the yarn, extract yarn wave characteristics based on image processing algorithms, and invert the dynamic tension changes of the yarn.

[0011] S6 uses a decoupling method to analyze the weighting coefficients of each vibration source on yarn tension fluctuations, defines the magnitude of each vibration source's effect, and establishes a quantitative mapping relationship between the vibration source characteristics and the dynamic tension of the yarn.

[0012] Based on the above technical solution, preferably, step S3, which calculates the weighting coefficient of each vibration source for yarn contact support through OPAX vibration transmission path analysis based on the reference acceleration signal of each vibration source and the response signal of the yarn response point, includes the following steps:

[0013] The load function that establishes a linear relationship between the reference acceleration of each vibration source and the equivalent excitation force it generates is obtained through experimental calibration, and the weighting coefficient is defined as the product of the corresponding path transmission frequency response function and the load function.

[0014] Based on the equivalent vibration model of the yarn, a system input-output model is established between the frequency domain response of the yarn response points and the reference accelerations of each vibration source. The expression is:

[0015]

[0016] In the formula, Y ( ω () represents the frequency domain response of the yarn response point. W i ( ω ) is the number to be determined i The weighting coefficients of each vibration source A i ( ω ) is the first i Reference acceleration at each vibration source.

[0017] Based on the above technical solution, preferably, step S3, which calculates the weighting coefficient of each vibration source for yarn contact support through OPAX vibration transmission path analysis based on the reference acceleration signal of each vibration source and the response signal of the yarn response point, further includes the following steps:

[0018] Based on the reference acceleration signals of each vibration source and the response signals of the yarn response points collected from multiple measurements, a cross power spectrum matrix of reference point acceleration and a cross power spectrum vector of reference point acceleration and response point response are constructed.

[0019] Based on the cross-power spectrum matrix of the reference point acceleration and the cross-power spectrum vectors of the reference point acceleration and the response point response, a matrix equation is constructed. The matrix equation is then solved based on the system input-output model to obtain the weight coefficient vectors for each transmission path. The expression is as follows:

[0020]

[0021] In the formula, G αα ( ω )for N × N The cross-power spectrum matrix, whose elements G αiαj ( ω () is the reference acceleration A i ( ω )and A j ( ω The cross-power spectrum of ) G αy ( ω )for N× A vector of 1s, whose elements G αiy ( ω () is the reference acceleration A i ( ω ) and yarn response point response Y ( ω The cross-power spectrum of W( ω ) for N A weighted coefficient vector of ×1, whose elements are the weighted coefficients corresponding to each vibration source. W i ( ω ).

[0022] Based on the above technical solution, preferably, step S3 involves weighting and synthesizing the acceleration signals of each vibration source with their corresponding weighting coefficients to obtain a multi-excitation joint input signal, including the following steps:

[0023] Based on the obtained weight coefficient vectors of each transmission path, the reference acceleration signals of each vibration source are weighted and superimposed in the frequency domain to synthesize a multi-excitation joint input frequency domain signal.

[0024] The multi-excitation joint input frequency domain signal is obtained by inverse Fourier transform to obtain the multi-excitation joint input time domain signal.

[0025] Based on the above technical solutions, preferably, step S4 includes: transmitting the multi-excitation combined input signal to the processor of the controllable vibration table; calling the signal in the control program of the controllable vibration table, analyzing the vibration function curve corresponding to the multi-excitation combined input signal, and identifying and reproducing the frequency, amplitude and direction angle parameters required for vibration, thereby simulating the composite vibration environment of the loom.

[0026] Based on the above technical solutions, preferably, step S5 includes the following sub-steps:

[0027] A sequence of vibration images of the yarn was acquired using a high-speed camera.

[0028] The image sequence is preprocessed, including grayscale conversion, filtering and denoising, and image enhancement, to obtain a standard graphic sequence;

[0029] Edge detection algorithms are used to detect the edges of each graphic in the standard graphic sequence and extract the yarn boundaries;

[0030] Based on the extracted yarn boundaries, a sub-pixel positioning algorithm is used to calculate the centerline position of the yarn;

[0031] By performing time-series analysis on the centerline position of the yarn in a continuous image sequence, the time series of the lateral displacement of the yarn midpoint is obtained.

[0032] Signal analysis is performed on the transverse displacement time series to extract the vibration characteristics of the yarn, including calculating the vibration amplitude through a peak detection algorithm and obtaining the vibration frequency through a fast Fourier transform.

[0033] Based on the string vibration theory model, a mapping relationship between yarn tension and vibration characteristics is established, and the dynamic tension of the yarn is calculated by inversion.

[0034] Based on the above technical solutions, preferably, in step S6, the weight coefficients of each vibration source on the yarn tension fluctuation are analyzed by decoupling method, including: constructing an equivalent vibration model of the yarn, and analyzing the weight of the excitation of each vibration source based on the equivalent vibration model of the yarn. In this case, the vibration source excitation is transformed into the transverse vibration of the yarn through structural transmission, and the transverse vibration causes the yarn length to change, which is transformed into tension fluctuation through elastic deformation.

[0035] The equivalent vibration model of the yarn is a tensioned string model excited by multiple foundations. It defines the dynamic equilibrium relationship between the yarn's inertia, damping, and elastic properties and the external excitation force through partial differential equations, expressed as follows:

[0036]

[0037] In the formula, y ( x , t ) represents the position of the yarnx and time t Lateral displacement at time ρ Yarn density, c This is the yarn damping coefficient. T The static tension of the yarn. f i ( t ) is the first i Each vibration source, after being transmitted through the structure, acts on the yarn position. x i The equivalent excitation force on, δ ( x-x i ) is the Dirac function.

[0038] Based on the above technical solutions, preferably, the yarn tension testing platform in step S1 includes a controllable vibration table and a yarn tension testing module mounted on it, wherein,

[0039] The number of controllable vibration tables is two, and the two controllable vibration tables are arranged in parallel with relative intervals to each other, and are used to simulate vibration sources at different positions in the loom respectively;

[0040] The yarn tension testing module includes a left serrated yarn reel, a middle serrated yarn reel, a right serrated yarn reel, a tension sensor, two motors, and an industrial camera.

[0041] The left and middle sawtooth yarn reels are set on a controllable vibration table, and the right sawtooth yarn reel is set on another controllable vibration table. The left, middle, and right sawtooth yarn reels can all rotate circumferentially around their respective center points and are in the same straight line position. The middle sawtooth yarn reel is located between the left and right sawtooth yarn reels.

[0042] The tension sensor is set on another controllable vibration table, located between the right sawtooth yarn reel and the middle sawtooth yarn reel. One end of the yarn is wound around the left sawtooth yarn reel, the middle sawtooth yarn reel, the tension sensor and the right sawtooth yarn reel in sequence.

[0043] Two motors are installed on two controllable vibration tables. One motor is connected to the central shaft of the middle sawtooth yarn wheel and is used to drive the middle sawtooth yarn wheel to rotate circumferentially; the other motor is connected to the central shaft of the right sawtooth yarn wheel and is used to drive the right sawtooth yarn wheel to rotate circumferentially.

[0044] An industrial camera is mounted on one side of a controllable vibration table to capture a sequence of vibration images of the yarn.

[0045] Secondly, the present invention provides a yarn vibration tension testing system for an air-jet loom, which is implemented using an experimental method for testing yarn vibration tension on an air-jet loom. The system includes:

[0046] The platform construction module is used to build a yarn tension testing platform, which includes a controllable vibration table and a yarn tension testing module installed thereon.

[0047] The vibration source signal acquisition module is used to identify the vibration sources and their distribution locations during the operation of the loom. Acceleration sensors are arranged at each vibration source, and the acceleration signals of each vibration source are collected during the operation of the loom.

[0048] The signal analysis and synthesis module is used to calculate the weighting coefficient of each vibration source to the yarn contact support through OPAX vibration transmission path analysis based on the reference acceleration signal of each vibration source and the response signal of the yarn response point. The acceleration signal of each vibration source is weighted and synthesized with the corresponding weighting coefficient to obtain the multi-excitation joint input signal.

[0049] The vibration environment simulation module is used to apply multiple excitation combined input signals to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom.

[0050] The image monitoring and inversion module is used to acquire vibration image sequences of yarn, extract yarn wave characteristics based on image processing algorithms, and invert the dynamic tension changes of the yarn.

[0051] The decoupling module analyzes the weighting coefficients of each vibration source on yarn tension fluctuations using decoupling methods, defines the magnitude of each vibration source's effect, and establishes a quantitative mapping relationship between vibration source characteristics and yarn dynamic tension.

[0052] Thirdly, the present invention also provides a computer-readable storage medium storing a program for a test method of vibration tension testing of yarn in an air-jet loom, wherein when the program is executed, a test method for vibration tension testing of yarn in an air-jet loom is implemented.

[0053] The experimental method and system for testing yarn vibration tension on air-jet looms of the present invention have the following advantages over the prior art:

[0054] (1) By constructing an equivalent dynamic model of yarn that integrates multi-source vibration excitation, and combining vibration transmission path analysis and weighted signal synthesis technology based on the OPAX method, the actual vibration state of the loom was simulated with high precision in the laboratory environment, which effectively solved the problem of inaccurate test results caused by neglecting the coupling excitation of multiple vibration sources in traditional test methods. At the same time, through the design of an independently controllable vibration table and non-contact image monitoring, the quantitative analysis and decoupling analysis of the contribution of each vibration source were realized, which provided reliable data support for the vibration reduction design of the loom and the control of yarn tension, and improved the accuracy and research efficiency of yarn dynamic tension testing.

[0055] (2) By establishing an accurate equivalent vibration physical model of yarn and combining it with the OPAX vibration transmission path analysis method, the complex multi-source coupling effect that cannot be directly measured is transformed into a driving signal that can be accurately calculated and synthesized. This method uses a measurable reference acceleration signal to indirectly characterize the contribution of each vibration source, and through frequency domain modeling and matrix operation, it realizes quantitative decoupling and high-precision calculation of the influence weight of each vibration source. The resulting multi-excitation joint input signal can reproduce the composite vibration condition of the actual operation of the loom in the laboratory environment with high fidelity according to the real contribution ratio of each vibration source, providing a reliable theoretical basis for accurately analyzing the root cause of yarn dynamic tension fluctuations and guiding the vibration reduction design of the loom. Attached Figure Description

[0056] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0057] Figure 1 This is a flowchart of the experimental method for testing the vibration tension of yarn on an air-jet loom according to the present invention;

[0058] Figure 2 This is a three-dimensional view of the test platform for the air-jet loom yarn vibration tension test method of the present invention;

[0059] Figure 3 This is a top view of the test platform for the test method of testing yarn vibration tension in an air-jet loom according to the present invention.

[0060] Figure 4 This is a schematic diagram of the vibration sources of the entire machine in the experimental method for testing yarn vibration tension of the air-jet loom of the present invention. Detailed Implementation

[0061] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0062] like Figures 1-4 As shown, in a first aspect, the present invention provides a method for testing the vibration tension of yarn on an air-jet loom, comprising the following steps:

[0063] S1. Construct a yarn tension testing platform, which includes a controllable vibration table and a yarn tension testing module installed thereon.

[0064] The yarn tension testing platform described in step S1 includes a controllable vibration table and a yarn tension testing module mounted on it, wherein,

[0065] The number of controllable vibration tables is two, and the two controllable vibration tables are arranged in parallel with relative intervals to each other, and are used to simulate vibration sources at different positions in the loom respectively;

[0066] It should be noted that two high-precision multi-axis controllable vibration tables are provided. These two vibration tables are fixedly installed in a relatively spaced and parallel manner. This layout can drive them independently to simulate different vibration sources that are spatially separated in a loom. By independently driving a single controllable vibration table, isolation and decoupling tests of specific vibration source excitation can be achieved, thereby accurately determining the independent influence of the vibration source on the yarn contact support.

[0067] For example, the left vibration table can be started separately to simulate weft insertion impact and analyze the vibration mode and tension change law of the yarn under this single excitation; then the right vibration table can be started separately to simulate shedding motion and evaluate its influence characteristics; finally, by comparing and analyzing the difference in yarn response under the combined action of a single vibration source and multiple vibration sources, the contribution weight of each vibration source to the dynamic tension of the yarn can be accurately quantified, providing precise data support for loom vibration reduction design and yarn tension control.

[0068] The yarn tension testing module includes a left sawtooth yarn reel 1, a middle sawtooth yarn reel 2, a right sawtooth yarn reel 3, a tension sensor 4, two motors 5, and an industrial camera 6. The left sawtooth yarn reel 1 and the middle sawtooth yarn reel 2 are mounted on one controllable vibration table, and the right sawtooth yarn reel 3 is mounted on another controllable vibration table. All three reels can rotate circumferentially around their respective center points and are positioned on the same straight line. The middle sawtooth yarn reel 2 is located between the left sawtooth yarn reel 1 and the right sawtooth yarn reel 3. The tension sensor 4 is mounted on the other controllable vibration table. On the controllable vibration table, located between the right sawtooth yarn reel 3 and the middle sawtooth yarn reel 2, one end of the yarn is wound sequentially through the left sawtooth yarn reel 1, the middle sawtooth yarn reel 2, the tension sensor 4, and the right sawtooth yarn reel 3; two motors 5 are respectively set on two controllable vibration tables, one motor 5 is connected to the central shaft of the middle sawtooth yarn reel 2, and is used to drive the middle sawtooth yarn reel 2 to rotate circumferentially; the other motor 5 is connected to the central shaft of the right sawtooth yarn reel 3, and is used to drive the right sawtooth yarn reel 3 to rotate circumferentially; an industrial camera 6 is set on one side of the controllable vibration table, and is used to collect the vibration image sequence of the yarn.

[0069] It should be noted that the yarn tension testing module also includes an LED light source to provide high brightness backlighting for the yarn. The LED light source and the industrial camera 6 are arranged opposite each other to form a backlight imaging system to ensure high-contrast imaging of the yarn edges. Furthermore, the tension sensor 4, the industrial camera 6, the two motors 5, and the controllers of the two controllable vibration tables are all connected to the host computer and data acquisition system, which can calculate the fluctuation amplitude, frequency, and tension change rate of the yarn online during the experiment and trigger an alarm when the preset threshold is exceeded. Moreover, the yarn tension testing platform is arranged in an isolated environment, encapsulating the vibration tables and the yarn tension testing module within it to reduce interference from external airflow and ambient light on high-precision measurements.

[0070] In this embodiment, an experimental platform was constructed by using two relatively independently set controllable vibration tables and combining them with a yarn testing module that integrates tension sensing, motor drive, and backlight imaging. This platform can not only simulate the single or combined excitation effects of vibration sources at different positions in the loom with high fidelity, realizing the isolation analysis and precise decoupling of the influence of multiple vibration sources, but also improve the monitoring accuracy and signal-to-noise ratio of yarn vibration mode and tension change by means of backlight imaging and isolation environment design. Thus, it provides reliable and efficient experimental means and data support for quantitatively studying the contribution weight of each vibration source to the dynamic tension of the yarn and optimizing the vibration reduction design and tension control strategy of the loom.

[0071] S2 identifies the vibration sources and their distribution locations during loom operation, arranges acceleration sensors at each vibration source, and collects the acceleration signals of each vibration source during loom operation.

[0072] It should be noted that this step is performed on a real, operating air-jet loom to identify key vibration sources and obtain their vibration data, which serves as the input benchmark for laboratory simulations.

[0073] Specifically, this includes: based on the mechanical structure and working principle of the air-jet loom, initially determining its main vibration sources, which typically include, but are not limited to, key transmission points of the weft insertion mechanism, shedding mechanism, main drive system, and warp feeding and take-up mechanisms; and using working modal analysis to identify the main vibration modes of the loom and their excitation locations during operation.

[0074] In this process, several acceleration sensors are initially deployed on the main structures of the loom, such as the frame and wall panels, while the loom is in operation. Vibration response data of the loom under typical speeds and process parameters are collected. The collected data is analyzed, and the main vibration modes of the loom under operating conditions and their excitation locations are determined by identifying peak frequencies and stability diagrams. These are the main vibration sources that contribute the most to the overall vibration.

[0075] S3, based on the reference acceleration signal of each vibration source and the response signal of the yarn response point, calculate the weight coefficient of each vibration source to the yarn contact support through OPAX vibration transmission path analysis, and weight and synthesize the acceleration signal of each vibration source with the corresponding weight coefficient to obtain the multi-excitation joint input signal;

[0076] For a linear time-invariant system, the yarn vibration response is represented as a linear superposition of the contributions from each excitation source. The frequency domain response expression at the key response points of the yarn is:

[0077]

[0078] In the formula, Y ( ω ( ) represents the Fourier transform of the vibration acceleration at the yarn response point. F i ( ω ) is the first i Equivalent excitation force f i ( t Fourier transform of ) H i ( ω ) is from the first i The frequency response function from the point of application of the excitation force to the yarn response point;

[0079] The OPAX vibration transmission path analysis method in this embodiment is a novel transmission path analysis method proposed by Karl Janssens et al. of LMS International. This method uses data under operating conditions supplemented by a small number of frequency response function tests to identify the operating condition load based on parametric modeling. Through the acquisition of operating condition data, the signals at the path input point, the response signals at the target point and the reference point are obtained. Then, the system frequency response function is tested, and the passive end excitation load is applied to the frequency response at the target point and the reference point. A parametric load identification model is established, and the operating condition load is represented by the signal at the path input point. Then, the operating condition load is calculated, and the load is calculated according to the parametric model. Finally, the contribution of each path is calculated based on the path contribution. This is existing technology and will not be described in detail here.

[0080] Step S3, based on the reference acceleration signals of each vibration source and the response signals of the yarn response points, calculates the weighting coefficients of each vibration source for the yarn contact support through OPAX vibration transmission path analysis, including the following steps:

[0081] The load function that establishes a linear relationship between the reference acceleration of each vibration source and the equivalent excitation force it generates is obtained through experimental calibration, and the weighting coefficient is defined as the product of the corresponding path transmission frequency response function and the load function.

[0082] It should be noted that, due to the equivalent excitation force Fi ( ω Since it cannot be directly measured, the core idea of ​​the OPAX method is introduced, which utilizes a measurable reference acceleration. A i ( ω Indirect characterization is achieved by using ) to establish the load function. L i ( ω Linking the two, the expression is:

[0083]

[0084] In the formula, Li ( ω () is the frequency response function. A i ( ω ) is the first i Reference acceleration at each vibration source.

[0085] Based on the frequency response function and load function from the point of application of the excitation force to the response point at the yarn contact support, the weighting coefficient of the vibration source is calculated, and the expression is:

[0086]

[0087] In the formula, W i ( ω ) is the first i The weighting coefficients of each vibration source H i ( ω ) is from the first i The frequency response function from the point of application of the excitation force to the yarn response point Li ( ω ) is the first i The load function of each vibration source; this coefficient integrates path transmission characteristics and load characteristics, and directly reflects the contribution intensity of the reference acceleration to the total response;

[0088] Substituting the above relationship into the frequency response formula, we get:

[0089] ;

[0090] Based on the equivalent vibration model of the yarn, a system input-output model is established between the frequency domain response of the yarn response points and the reference accelerations of each vibration source. The expression is:

[0091]

[0092] In the formula, Y ( ω () represents the frequency domain response of the yarn response point. W i (ω ) is the number to be determined i The weighting coefficients of each vibration source A i ( ω ) is the first i Reference acceleration at each vibration source.

[0093] Step S3 also includes the following steps:

[0094] Based on the reference acceleration signals of each vibration source and the response signals of the yarn response points collected from multiple measurements, a cross power spectrum matrix of reference point acceleration and a cross power spectrum vector of reference point acceleration and response point response are constructed.

[0095] Based on the cross-power spectrum matrix of the reference point acceleration and the cross-power spectrum vectors of the reference point acceleration and the response point response, a matrix equation is constructed. The matrix equation is then solved based on the system input-output model to obtain the weight coefficient vectors for each transmission path. The expression is as follows:

[0096]

[0097] In the formula, G αα ( ω )for N × N The cross-power spectrum matrix, whose elements G αiαj ( ω () is the reference acceleration A i ( ω )and A j ( ω The cross-power spectrum of ) G αy ( ω )for N× A vector of 1s, whose elements G αiy ( ω () is the reference acceleration A i ( ω ) and yarn response point response Y ( ω The cross-power spectrum of W( ω ) for N A weighted coefficient vector of ×1, whose elements are the weighted coefficients corresponding to each vibration source. W i ( ω ).

[0098] Step S3 involves weighting and synthesizing the acceleration signals of each vibration source with their corresponding weighting coefficients to obtain the multi-excitation joint input signal, including the following steps:

[0099] Based on the obtained weight coefficient vectors of each transmission path, the reference acceleration signals of each vibration source are weighted and superimposed in the frequency domain to synthesize a multi-excitation joint input frequency domain signal, as expressed in the following expression:

[0100]

[0101] In the formula, A synth ( ω To synthesize a multi-excitation joint input frequency domain signal, the synthesized signal is a virtual acceleration signal. The energy of each frequency component contained in the signal has been allocated according to the contribution ratio of each vibration source to the yarn response. When this signal drives the vibration platform, its effect is theoretically equivalent to the effect of all vibration sources acting simultaneously.

[0102] The multi-excitation joint input frequency domain signal is transformed by inverse Fourier transform to obtain the multi-excitation joint input signal in the time domain, expressed as:

[0103]

[0104] In the formula, α syntht ( ω The signal is the combined input signal of multiple excitations that is finally loaded onto the vibration table controller. It contains all the vibration characteristics of each vibration source after weighting according to the actual contribution ratio, and is used to drive the vibration table in the laboratory to simulate the actual working conditions of the loom in high fidelity.

[0105] This embodiment establishes an accurate physical model of yarn equivalent vibration and combines it with the OPAX vibration transmission path analysis method to transform the complex multi-source coupling effect, which cannot be directly measured, into a driving signal that can be accurately calculated and synthesized. This method uses a measurable reference acceleration signal to indirectly characterize the contribution of each vibration source, and through frequency domain modeling and matrix operations, it achieves quantitative decoupling and high-precision calculation of the influence weight of each vibration source. The resulting multi-excitation joint input signal can reproduce the composite vibration condition of the actual operation of the loom in a laboratory environment with high fidelity according to the true contribution ratio of each vibration source, providing a reliable theoretical basis for accurately analyzing the root cause of yarn dynamic tension fluctuations and guiding the vibration reduction design of the loom.

[0106] S4 applies a multi-excitation combined input signal to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom;

[0107] Step S4 includes: transmitting the multi-excitation combined input signal to the processor of the controllable vibration table; calling the signal in the control program of the controllable vibration table, analyzing the vibration function curve corresponding to the multi-excitation combined input signal, and identifying and reproducing the frequency, amplitude and direction angle parameters required for vibration, and simulating the composite vibration environment of the loom.

[0108] S5 acquires a sequence of vibration images of the yarn, extracts the yarn wave characteristics based on image processing algorithms, and inverts the dynamic tension changes of the yarn.

[0109] Step S5 includes the following sub-steps:

[0110] A sequence of vibration images of the yarn was acquired using a high-speed camera.

[0111] The image sequence is preprocessed, including grayscale conversion, filtering and denoising, and image enhancement, to obtain a standard graphic sequence;

[0112] Edge detection algorithms are used to detect the edges of each graphic in the standard graphic sequence and extract the yarn boundaries;

[0113] Based on the extracted yarn boundaries, a sub-pixel positioning algorithm is used to calculate the centerline position of the yarn;

[0114] By performing time-series analysis on the centerline position of the yarn in a continuous image sequence, the time series of the lateral displacement of the yarn midpoint is obtained.

[0115] Signal analysis is performed on the transverse displacement time series to extract the vibration characteristics of the yarn, including calculating the vibration amplitude through a peak detection algorithm and obtaining the vibration frequency through a fast Fourier transform.

[0116] Based on the string vibration theory model, a mapping relationship between yarn tension and vibration characteristics is established, and the dynamic tension of the yarn is calculated by inversion. The yarn tension and vibration frequency satisfy the following relationship:

[0117]

[0118] In the formula, ρ Yarn density, L For yarn span, f v The frequency is the vibration frequency.

[0119] It should be noted that a high-frequency industrial camera 6 is used to capture images of the yarn test section. The camera is equipped with a telecentric lens to reduce perspective error. The test environment is equipped with a high-brightness LED backlight source to form a transmission illumination system, ensuring that the yarn presents a high-contrast dark field outline in the image. The camera is synchronized with the vibration table control system through a trigger signal to ensure the consistency of the image sequence with the timing of the vibration excitation.

[0120] After the acquired raw images are converted to grayscale, Gaussian filtering is used to suppress noise. The yarn movement region is extracted by subtracting the current frame image from the static background image using the background subtraction method. The image is binarized using an adaptive threshold segmentation algorithm, and small noise points are eliminated by combining morphological opening operations. Finally, the region of interest of the yarn in each frame image is accurately located through connected component analysis.

[0121] The centerline position of the yarn is calculated using a sub-pixel positioning algorithm. Specifically, the yarn edges are extracted with sub-pixel precision using the Steger algorithm or the grayscale centroid method. The specific steps are as follows:

[0122] First, the image gradient is calculated using the Sobel operator. Then, grayscale interpolation is performed along the normal direction. Quadratic curve fitting is used to locate the gradient extrema, thus obtaining the yarn edge coordinates with an accuracy of 0.1 pixels. The yarn centerline position is then calculated based on the left and right edge coordinates.

[0123]

[0124] in y c ( x () represents the yarn's coordinates in the image column. x The centerline position.

[0125] This embodiment achieves high-precision, non-destructive, real-time monitoring of yarn dynamic tension changes by constructing a non-contact monitoring system. The method utilizes backlight imaging and sub-pixel positioning technology to improve the extraction accuracy and anti-interference capability of yarn vibration patterns, overcoming the limitations of traditional contact measurements that are susceptible to mechanical vibration and difficult to capture high-frequency dynamic characteristics. Finally, by converting image sequences into precise displacement time-series data and retrieving yarn dynamic tension based on a mature string vibration theory model, reliable data support is provided for online quality monitoring of the weaving process.

[0126] S6 uses a decoupling method to analyze the weighting coefficients of each vibration source on yarn tension fluctuations, defines the magnitude of each vibration source's effect, and establishes a quantitative mapping relationship between the vibration source characteristics and the dynamic tension of the yarn.

[0127] In step S6 of this embodiment, the weighting coefficients of each vibration source on the yarn tension fluctuation are analyzed by decoupling method, including: constructing an equivalent vibration model of the yarn, and analyzing the influence weight of each vibration source excitation based on the equivalent vibration model of the yarn. The vibration source excitation is transformed into the transverse vibration of the yarn through structural transmission. The transverse vibration causes the yarn length to change, which is transformed into tension fluctuation through elastic deformation.

[0128] The equivalent vibration model of the yarn is a tensioned string model excited by multiple foundations. It defines the dynamic equilibrium relationship between the yarn's inertia, damping, and elastic properties and the external excitation force through partial differential equations, expressed as follows:

[0129]

[0130] In the formula, y ( x , t ) represents the position of the yarn x and time tLateral displacement at time ρ Yarn density, c This is the yarn damping coefficient. T The static tension of the yarn. f i ( t ) is the first i Each vibration source, after being transmitted through the structure, acts on the yarn position. x i The equivalent excitation force on, δ ( x-x i ) is the Dirac function.

[0131] This embodiment constructs an equivalent dynamic model of yarn that integrates multi-source vibration excitation, and combines vibration transmission path analysis and weighted signal synthesis technology based on the OPAX method to achieve high-precision simulation of the actual vibration state of a loom in a laboratory environment, and provides effective support for quantitatively analyzing the effect mechanism of various vibration sources on tension fluctuations.

[0132] Secondly, the present invention provides a yarn vibration tension testing system for an air-jet loom, which is implemented using an experimental method for testing yarn vibration tension on an air-jet loom. The system includes:

[0133] The platform construction module is used to build a yarn tension testing platform, which includes a controllable vibration table and a yarn tension testing module installed thereon.

[0134] The vibration source signal acquisition module is used to identify the vibration sources and their distribution locations during the operation of the loom. Acceleration sensors are arranged at each vibration source, and the acceleration signals of each vibration source are collected during the operation of the loom.

[0135] The signal analysis and synthesis module is used to calculate the weighting coefficient of each vibration source on the dynamic tension fluctuation of the yarn through OPAX vibration transmission path analysis based on the reference acceleration signal of each vibration source and the response signal of the yarn response point. The acceleration signal of each vibration source is weighted and synthesized with the corresponding weighting coefficient to obtain the multi-excitation joint input signal.

[0136] The vibration environment simulation module is used to apply multiple excitation combined input signals to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom.

[0137] The image monitoring and inversion module is used to acquire vibration image sequences of yarn, extract yarn wave characteristics based on image processing algorithms, and invert the dynamic tension changes of the yarn.

[0138] The decoupling module analyzes the weighting coefficients of each vibration source on yarn tension fluctuations using decoupling methods, defines the magnitude of each vibration source's effect, and establishes a quantitative mapping relationship between vibration source characteristics and yarn dynamic tension.

[0139] Thirdly, the present invention also provides a computer-readable storage medium storing a program for a test method of vibration tension testing of yarn in an air-jet loom, wherein when the program is executed, a test method for vibration tension testing of yarn in an air-jet loom is implemented.

[0140] It should be noted that this system corresponds to the above-mentioned method for testing the vibration tension of yarn on an air-jet loom. All implementation methods in the above-mentioned method embodiments are applicable to the embodiments of this system and can achieve the same technical effect.

[0141] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0142] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the system and modules described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0143] In the embodiments provided by this invention, it should be understood that the disclosed systems and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0144] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0145] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0146] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0147] Furthermore, it should be noted that in the system and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent solutions of the present invention. Moreover, the steps performing the above series of processes can naturally be executed in the order described, but are not necessarily required to be executed in chronological order; some steps can be executed in parallel or independently of each other. Those skilled in the art will understand that all or any step or component of the method and apparatus of the present invention can be implemented in any computing device (including processors, storage media, etc.) or network of computing devices, in hardware, firmware, software, or a combination thereof. This is something that those skilled in the art can achieve by using their basic programming skills after reading the description of the present invention.

[0148] Therefore, the object of the present invention can also be achieved by running a program or a set of programs on any computing system. The computing system can be a known general-purpose system. Therefore, the object of the present invention can also be achieved simply by providing a program product containing program code implementing the method or apparatus. That is, such a program product also constitutes the present invention, and the storage medium storing such a program product also constitutes the present invention. Obviously, the storage medium can be any known storage medium or any storage medium developed in the future. It should also be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent to the present invention. Furthermore, the steps performing the above series of processes can naturally be performed in the order described, but are not necessarily required to be performed in chronological order. Some steps can be performed in parallel or independently of each other.

[0149] 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 spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for testing the vibration tension of yarn on an air-jet loom, characterized in that, Includes the following steps: S1. Construct a yarn tension testing platform, which includes a controllable vibration table and a yarn tension testing module installed thereon. S2, identify the vibration sources and their distribution locations during loom operation, arrange acceleration sensors at each vibration source, and collect the acceleration signals of each vibration source during loom operation; S3, based on the reference acceleration signal of each vibration source and the response signal of the yarn response point, calculate the weight coefficient of each vibration source to the yarn contact support through OPAX vibration transmission path analysis, and weight and synthesize the acceleration signal of each vibration source with the corresponding weight coefficient to obtain the multi-excitation joint input signal; S4 applies a multi-excitation combined input signal to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom; S5: Acquire a sequence of vibration images of the yarn, extract yarn wave characteristics based on image processing algorithms, and invert the dynamic tension changes of the yarn. S6. By using the decoupling method, the weighting coefficients of each vibration source on the yarn tension fluctuation are analyzed to define the magnitude of the effect of each vibration source and establish a quantitative mapping relationship between the vibration source characteristics and the dynamic tension of the yarn. An equivalent vibration model of yarn is constructed, and the influence weight of each vibration source excitation is analyzed based on the equivalent vibration model of yarn. Among them, the vibration source excitation is transformed into the transverse vibration of the yarn through structural transmission. The transverse vibration causes the yarn length to change, which is transformed into tension fluctuation through elastic deformation. The equivalent vibration model of the yarn is a tensioned string model excited by multiple foundations. It defines the dynamic equilibrium relationship between the yarn's inertia, damping, and elastic properties and the external excitation force through partial differential equations, expressed as follows: ； In the formula, y ( x , t ) represents the position of the yarn x and time t Lateral displacement at time ρ Yarn density, c This is the yarn damping coefficient. T The static tension of the yarn. f i ( t ) is the first i Each vibration source, after being transmitted through the structure, acts on the yarn position. x i The equivalent excitation force on, δ ( xx i ) is the Dirac function.

2. The experimental method for testing yarn vibration tension on an air-jet loom as described in claim 1, characterized in that, In step S3, based on the reference acceleration signals of each vibration source and the response signals at the yarn contact support, the weighting coefficients of each vibration source to the yarn contact support are calculated through OPAX vibration transmission path analysis, including the following steps: The load function that establishes a linear relationship between the reference acceleration of each vibration source and the equivalent excitation force it generates is obtained through experimental calibration, and the weighting coefficient is defined as the product of the corresponding path transmission frequency response function and the load function. Establish a system input-output model between the frequency domain response at the yarn contact support point and the reference acceleration of each vibration source, with the expression as follows: ； In the formula, Y ( ω () represents the frequency domain response at the point where the yarn contacts the support. W i ( ω ) is the number to be determined i The weighting coefficients of each vibration source A i ( ω ) is the first i Reference acceleration at each vibration source.

3. The experimental method for testing yarn vibration tension on an air-jet loom as described in claim 2, characterized in that, Step S3, which calculates the weighting coefficient of each vibration source for yarn contact support based on the reference acceleration signal of each vibration source and the response signal of the yarn response point through OPAX vibration transmission path analysis, also includes the following steps: Based on the reference acceleration signals of each vibration source and the response signals of the yarn response points collected from multiple measurements, a cross power spectrum matrix of reference point acceleration and a cross power spectrum vector of reference point acceleration and response point response are constructed. Based on the cross-power spectrum matrix of the reference point acceleration and the cross-power spectrum vectors of the reference point acceleration and the response point response, a matrix equation is constructed. The matrix equation is then solved based on the system input-output model to obtain the weight coefficient vectors for each transmission path. The expression is as follows: ； In the formula, G aa ( ω )for N × N The cross-power spectrum matrix, whose elements G aiaj ( ω () is the reference acceleration A i ( ω )and A j ( ω The cross-power spectrum of ) G ay ( ω )for N× A vector of 1s, whose elements G aiy ( ω () is the reference acceleration A i ( ω ) and yarn response point response Y ( ω The cross-power spectrum of W( ω ) for N A weighted coefficient vector of ×1, whose elements are the weighted coefficients corresponding to each vibration source. W i ( ω ).

4. The experimental method for testing the vibration tension of yarn on an air-jet loom as described in claim 3, characterized in that: In step S3, the acceleration signals of each vibration source are weighted and synthesized with their corresponding weighting coefficients to obtain a multi-excitation joint input signal, including the following steps: Based on the obtained weight coefficient vectors of each transmission path, the reference acceleration signals of each vibration source are weighted and superimposed in the frequency domain to synthesize a multi-excitation joint input frequency domain signal. The multi-excitation joint input frequency domain signal is obtained by inverse Fourier transform to obtain the multi-excitation joint input time domain signal.

5. The experimental method for testing yarn vibration tension on an air-jet loom as described in claim 1, characterized in that, Step S4 includes: transmitting the multi-excitation combined input signal to the processor of the controllable vibration table; calling the signal in the control program of the controllable vibration table, analyzing the vibration function curve corresponding to the multi-excitation combined input signal, and identifying and reproducing the frequency, amplitude and direction angle parameters required for vibration, and simulating the composite vibration environment of the loom.

6. The experimental method for testing yarn vibration tension on an air-jet loom as described in claim 1, characterized in that, Step S5 includes the following sub-steps: A sequence of vibration images of the yarn was acquired using a high-speed camera. The image sequence is preprocessed, including grayscale conversion, filtering and denoising, and image enhancement, to obtain a standard graphic sequence; Edge detection algorithms are used to detect the edges of each graphic in the standard graphic sequence and extract the yarn boundaries; Based on the extracted yarn boundaries, a sub-pixel positioning algorithm is used to calculate the centerline position of the yarn; By performing time-series analysis on the centerline position of the yarn in a continuous image sequence, the time series of the lateral displacement of the yarn midpoint is obtained. Signal analysis is performed on the transverse displacement time series to extract the vibration characteristics of the yarn, including calculating the vibration amplitude through a peak detection algorithm and obtaining the vibration frequency through a fast Fourier transform. Based on the string vibration theory model, a mapping relationship between yarn tension and vibration characteristics is established, and the dynamic tension of the yarn is calculated by inversion.

7. The experimental method for testing the vibration tension of yarn on an air-jet loom as described in claim 1, characterized in that: The yarn tension testing platform described in step S1 includes a controllable vibration table and a yarn tension testing module mounted on it, wherein, The number of controllable vibration tables is two, and the two controllable vibration tables are arranged in parallel with relative intervals to each other, and are used to simulate vibration sources at different positions in the loom respectively; The yarn tension testing module includes a left sawtooth yarn reel (1), a middle sawtooth yarn reel (2), a right sawtooth yarn reel (3), a tension sensor (4), two motors (5), and an industrial camera (6). The left sawtooth yarn wheel (1) and the middle sawtooth yarn wheel (2) are set on a controllable vibration table, and the right sawtooth yarn wheel (3) is set on another controllable vibration table. The left sawtooth yarn wheel (1), the middle sawtooth yarn wheel (2) and the right sawtooth yarn wheel (3) can all rotate around their respective center points and are in the same straight line position. The middle sawtooth yarn wheel (2) is located between the left sawtooth yarn wheel (1) and the right sawtooth yarn wheel (3). The tension sensor (4) is set on another controllable vibration table and is located between the right sawtooth yarn wheel (3) and the middle sawtooth yarn wheel (2). One end of the yarn is wound around the left sawtooth yarn wheel (1), the middle sawtooth yarn wheel (2), the tension sensor (4) and the right sawtooth yarn wheel (3) in sequence. Two motors (5) are set on two controllable vibration tables. One motor (5) is connected to the central shaft of the middle sawtooth yarn wheel (2) and is used to drive the middle sawtooth yarn wheel (2) to rotate circumferentially. The other motor (5) is connected to the central shaft of the right sawtooth yarn wheel (3) and is used to drive the right sawtooth yarn wheel (3) to rotate circumferentially. An industrial camera (6) is set on one side of a controllable vibration table to acquire vibration image sequences of the yarn.

8. A system for testing the vibration tension of yarn on an air-jet loom, implemented using the experimental method for testing the vibration tension of yarn on an air-jet loom as described in any one of claims 1 to 7, characterized in that, The system includes: The platform construction module is used to build a yarn tension testing platform, which includes a controllable vibration table and a yarn tension testing module installed thereon. The vibration source signal acquisition module is used to identify the vibration sources and their distribution locations during the operation of the loom. Acceleration sensors are arranged at each vibration source, and the acceleration signals of each vibration source are collected during the operation of the loom. The signal analysis and synthesis module is used to calculate the weighting coefficient of each vibration source to the yarn contact support through OPAX vibration transmission path analysis based on the reference acceleration signal of each vibration source and the response signal of the yarn response point. The acceleration signal of each vibration source is weighted and synthesized with the corresponding weighting coefficient to obtain the multi-excitation joint input signal. The vibration environment simulation module is used to apply multiple excitation combined input signals to the controllable vibration table of the yarn tension test platform to simulate the complex vibration environment of the loom. The image monitoring and inversion module is used to acquire vibration image sequences of yarn, extract yarn fluctuation characteristics based on image processing algorithms, and invert the dynamic tension changes of the yarn.

9. A computer-readable storage medium, characterized in that: The storage medium stores a test method program for testing the vibration tension of yarn in an air-jet loom. When the test method program for testing the vibration tension of yarn in an air-jet loom is executed, it implements the test method for testing the vibration tension of yarn in an air-jet loom as described in any one of claims 1 to 7.

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