A method and system for analyzing the vibration characteristics of an air jet loom

Abstract

The application provides a method and system for analyzing vibration characteristics of an air jet loom, the method comprising the following steps: independently exciting multiple motion mechanisms of the air jet loom at different times, and collecting vibration response signals of the loom under excitation of each motion mechanism; using a random decrement method to extract free responses of the corresponding motion mechanisms from the vibration response signals under excitation of each motion mechanism, and using a least square complex exponential method to identify, so as to obtain modal parameters and frequency response functions under excitation of each motion mechanism; respectively establishing vibration transmission models between vibration responses of the loom and excitation of the motion mechanisms according to types of the motion mechanisms; obtaining motion parameters of the motion mechanisms of each target point of interest, and substituting the motion parameters and the frequency response functions of each motion mechanism into the corresponding vibration transmission models, so as to calculate vibration responses of the target points of interest in a rectangular space coordinate system, and obtain vibration characteristic distribution of the air jet loom, and the method can accurately predict the vibration characteristics of the air jet loom under different working conditions.

Description

Technical Field

[0001] This invention relates to the field of vibration analysis technology for textile machinery, and in particular to a method and system for analyzing the vibration characteristics of an air-jet loom. Background Technology

[0002] In the textile industry, air-jet looms, as high-efficiency, high-speed looms, are experiencing continuously increasing operating speeds. However, the resulting vibration problems are becoming increasingly prominent. The motion mechanism of an air-jet loom generates dynamic excitations during reciprocating motion. These excitations are transmitted to the frame through the transmission system, causing frame vibration. Frame vibration not only affects the stability, precision, and fabric quality of the loom but also generates noise, reduces working comfort, accelerates the wear of mechanical parts, and shortens the equipment's lifespan.

[0003] In the vibration analysis and optimization of air-jet looms, the lack of precise mathematical models for the vibration transmission relationship between different types of motion mechanisms and the frame makes it difficult to accurately predict the excitation transmission and corresponding vibration response of the frame under complex working conditions. Furthermore, the lack of effective methods to closely and accurately correlate the motion parameters of the motion mechanism with the vibration response of the frame results in an inability to fully grasp the vibration characteristic distribution of various parts of the frame, thereby reducing the vibration analysis effect of air-jet looms. Summary of the Invention

[0004] In view of this, the present invention proposes a vibration characteristic analysis method and system for air-jet looms. It establishes vibration transmission models between the frame vibration response and the excitation of the motion mechanism for different types of motion mechanisms, accurately describes the vibration transmission relationship, and can accurately obtain the vibration characteristic distribution of the frame, thereby improving the vibration analysis effect of air-jet looms.

[0005] The technical solution of this invention is implemented as follows: This invention provides a method for analyzing the vibration characteristics of an air-jet loom, comprising the following steps: S1, performs time-division independent excitation on multiple motion mechanisms of the air-jet loom, and collects the frame vibration response signal under the excitation of each motion mechanism; S2, for the vibration response signals of each motion mechanism under excitation, the free response of the corresponding motion mechanism is extracted by random subtraction method, and the modal parameters and frequency response functions of each motion mechanism under excitation are obtained by least squares complex exponential method. S3. Based on the type of motion mechanism, establish vibration transmission models between frame vibration response and motion mechanism excitation respectively; The types of motion mechanisms include oscillating motion and linear motion. Based on the oscillating motion mechanism, the relationship between the frequency response function of the frame end acceleration and the nominal frequency response function of each oscillating joint is established. Based on the linear motion mechanism, the relationship between the frame frequency domain displacement response based on the kinematic Jacobian matrix and the input of each mechanism is established. S4. Based on the preset target focus point on the frame, the inverse kinematics of the air-jet loom is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular space coordinate system, and the vibration characteristic distribution of the air-jet loom frame is obtained.

[0006] Based on the above technical solutions, preferably, step S1, which involves independently exciting multiple motion mechanisms of the air-jet loom in a time-division manner and collecting the frame vibration response signal under the excitation of each motion mechanism, includes the following sub-steps: S11, the air-jet loom includes a heald frame, a beating-off rocker, a warp loosening link, a tie rod, and a dynamic back beam motion mechanism, which sequentially and independently excites multiple motion mechanisms of the air-jet loom in a time-division manner; The control mechanism performs reciprocating acceleration and deceleration motion, accelerating it to a preset speed value, and then immediately reverses the acceleration until the speed drops to zero. After a random time interval, the acceleration and deceleration motion is repeated in the opposite direction, and the absolute value of the acceleration remains constant during the acceleration and deceleration motion. Through multiple alternating reciprocating acceleration and deceleration motions, the individual motion mechanism of the air-jet loom generates excitation force. S12 uses sensors arranged on the frame to collect vibration acceleration signals along the X, Y, and Z directions generated by the excitation of each motion mechanism, which are used as the frame vibration response signals under the excitation of the motion mechanism.

[0007] Based on the above technical solutions, preferably, the vibration response signal of each motion mechanism under excitation in step S2 is used to extract the free response of the corresponding motion mechanism using a random subtraction method, which includes the following sub-steps: S21, Set the displacement threshold A, and construct based on the displacement threshold. x = Threshold line of A; S22, obtain the intersection positions with the threshold line from the vibration response signal, and extract the time points corresponding to each intersection position; S23, taking the time point corresponding to each intersection as the starting time, extract a fixed-length signal from the vibration response signal to form a signal segment; S24, align all signal segments on the time axis, and average the aligned signal segments to obtain the free response of the motion mechanism.

[0008] Based on the above technical solutions, preferably, step S2, which uses the least squares complex exponential method to solve for the modal parameters and frequency response function under the excitation of the corresponding motion mechanism, includes the following sub-steps: S25, construct the free response of the motion mechanism as a discrete time series, and construct the Hankel matrix H based on the discrete time series; S26. Based on the Hankel matrix, an error function with the characteristic polynomial coefficient vector as the variable is defined. The characteristic polynomial coefficient vector that minimizes the error function is solved by the least squares complex exponential method. S27. Construct the characteristic polynomial based on the coefficient vector of the characteristic polynomial and solve for the roots of the characteristic polynomial; calculate the complex frequency poles of the system based on the roots of the characteristic polynomial. S28. Calculate the modal frequencies and damping ratios of the corresponding motion mechanism under excitation based on the real and imaginary parts of the complex frequency poles of the system. S29. Based on the amplitude vector corresponding to the complex frequency poles of the system, extract the mode shape of the system, and combine the mode frequency, damping ratio and mode shape to obtain the frequency response function under the excitation of the corresponding motion mechanism.

[0009] Based on the above technical solutions, preferably, the error function is defined as follows: J =2Ca, where C=H T H,a = [a 2N …a 0 ] T , where 'a' is the coefficient vector of the characteristic polynomial, by letting J Solving for 0, the least squares solution for the characteristic polynomial coefficient vector a is: .

[0010] Based on the above technical solutions, preferably, step S3, which establishes the relationship between the acceleration frequency response function at the end of the frame and the nominal frequency response function of each swing joint based on the swing motion mechanism, includes the following sub-steps: S311, the beat-up rocker motion mechanism has three swing joints. Based on the transmission equations of an air-jet loom, the kinematic parameters of the beat-up rocker motion mechanism are determined, including the rotational speed ξ=[ξ1,ξ2,ξ3] of each swing joint. T and the corresponding joint transmission angle i =[ i 1, i 2, i 3] T ; S312, based on the rotational motion of the three swing joints and the joint transmission angle vectors, establish a kinematic model between the end-frame pose and the transmission angles of each swing joint, expressed as: ; In the formula, These are the antisymmetric matrix operators corresponding to the spinors of the three joint motions. p 0 represents the initial pose of the rack. i 1, i 2, i 3 represents the transmission angle vectors of the three joints; S313, by taking the second derivative of the kinematic model and performing a Fourier transform, a linear relationship is established between the frequency response function of the frame end acceleration and the nominal frequency response functions of each swing joint, resulting in a vibration transmission model for the swing motion type, expressed as: ; In the formula, oh 2 I x ( oh Let Vec(·) be the frequency response function of the acceleration at the end of the rack, and Vec(·) be the matrix vectorization operator. T x Let be the second-order partial derivative matrix of the frame pose with respect to the transmission angle. H i (ω) is the convolution combination matrix of the joint frequency response. T θ The matrix Φ( is the second-order partial derivative of the frame end pose with respect to the transmission angle;) oh ) represents the nominal frequency response function vector of each swing joint, Φ( oh =[Φ1(ω),Φ2(ω),Φ3(ω)] T .

[0011] Based on the above technical solutions, preferably, step S3, which establishes the relationship between the frame frequency domain displacement response and the inputs of each mechanism based on the kinematic Jacobian matrix, includes the following sub-steps: S321, the linear motion mechanism includes a heald frame motion mechanism, a loosening linkage motion mechanism, and a pull rod motion mechanism. The heald frame motion mechanism moves in the vertical direction, and the loosening linkage motion mechanism moves at an angle to the horizontal direction. ϕ Angle motion; the linkage mechanism moves in the left and right directions; obtain the displacement vectors of the heald frame mechanism, the loosening linkage mechanism, and the linkage mechanism respectively; S322, based on the displacement vectors and included angles of the heald frame motion mechanism, the loosening linkage motion mechanism, and the tie rod motion mechanism, establish the composite displacement vector of the frame in the fixed plane coordinate system, expressed as: ; In the formula, g ( t () represents the resultant displacement of the frame in the plane. x s2(t) is the displacement vector of the pull rod mechanism; s3(t) is the displacement vector of the release rod mechanism; y 1(t) is the displacement vector of the heald frame mechanism; S323, differentiate the composite displacement vector to establish the kinematic relationship between the frame acceleration and each linear motion mechanism, and perform a Fourier transform to convert it to the frequency domain to obtain the relationship between the frame acceleration frequency response and the displacement frequency response of each linear motion mechanism. The expression is: ; In the formula, For Fourier transform, For rack acceleration, J ( q ) is the kinematic Jacobian matrix; Q ( oh ) represents the displacement frequency domain response of each linear mechanism. Q ( oh )=[ Y 1( oh ), X 2( oh ),S3( oh )] T , Y 1( oh ( ) represents the displacement frequency domain response of the heald frame mechanism. X 2( oh S3 is the displacement frequency domain response of the linkage mechanism. oh The displacement frequency domain response of the linkage mechanism is given. oh Angular velocity; S324, combining the frequency domain dynamic equations of the frame, derives and establishes a vibration transmission model between the frequency domain displacement response of the frame and the frequency domain input of each linear motion mechanism.

[0012] Based on the above technical solutions, preferably, the step S324, which combines the frequency domain dynamic equations of the frame to derive and establish a vibration transmission model between the frequency domain displacement response of the frame and the frequency domain input of each linear motion mechanism, includes the following steps: S3241, Establish the frequency domain dynamic equations of the rack, the expression is: ; In the formula, F(ω) is the excitation vector of the linear mechanism on the frame, I is the identity matrix, ΛK is the diagonal compensation coefficient matrix of stiffness, ΛC is the diagonal compensation coefficient matrix of damping, ΛM is the diagonal compensation coefficient matrix of mass; G(ω) is the frequency domain displacement response of the frame. M is the rack equivalent mass matrix; Here is the overall stiffness matrix of the frame; This represents the total damping matrix of the rack. The expression for the overall stiffness matrix of the frame is: ; In the formula, K0 is the initial linear stiffness matrix of the frame, and ΔK(q) is the displacement-dependent stiffness correction matrix. It is a nonlinear stiffness matrix; The expression for the total damping matrix of the rack is: ; In the formula, C0 is the initial linear damping matrix of the frame, and ΔC(q) is the displacement-dependent damping correction matrix. It is a nonlinear damping matrix; S3242, based on the frequency domain dynamic equations of the frame and the relationship between the frame's acceleration frequency response and the displacement frequency response of each linear motion mechanism, a vibration transmission model between the frame's frequency domain displacement response and the frequency domain input of each linear motion mechanism is derived and established. The expression is: ; ; In the formula, H( oh ) is the equivalent frequency response function matrix of the rack.

[0013] Secondly, the present invention also provides a vibration characteristic analysis system for an air-jet loom, implemented using an air-jet loom vibration characteristic analysis method, comprising: The data acquisition module is used to independently excite multiple motion mechanisms of the air-jet loom in a time-division manner and to collect the frame vibration response signal under the excitation of each motion mechanism; The identification module is used to extract the free response of the corresponding motion mechanism from the vibration response signal under the excitation of each motion mechanism using the random subtraction method, and to identify the modal parameters and frequency response function of each motion mechanism under the excitation using the least squares complex exponential method. The model building module is used to establish vibration transmission models between frame vibration response and motion mechanism excitation according to the type of motion mechanism. The types of motion mechanisms include oscillating motion and linear motion. Based on the oscillating motion mechanism, the relationship between the frequency response function of the frame end acceleration and the nominal frequency response function of each oscillating joint is established. Based on the linear motion mechanism, the relationship between the frame frequency domain displacement response based on the kinematic Jacobian matrix and the input of each mechanism is established. The distribution generation module is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position by solving the inverse kinematics of the air-jet loom based on the preset target focus point on the frame. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular coordinate system and obtain the vibration characteristic distribution of the air-jet loom frame.

[0014] Thirdly, the present invention also provides a computer-readable storage medium storing a program for analyzing the vibration characteristics of an air-jet loom, wherein the program, when executed, implements the method for analyzing the vibration characteristics of an air-jet loom.

[0015] The vibration characteristic analysis method and system for air-jet looms of the present invention have the following advantages over the prior art: (1) By independently exciting each motion mechanism of the air jet loom and collecting the frame vibration response signal, the modal parameters and frequency response function are accurately obtained by using the random subtraction method and the least squares complex exponential method. For different types of motion mechanisms, vibration transmission models between frame vibration response and motion mechanism excitation are established to accurately describe the vibration transmission relationship. The motion parameters are solved by inverse kinematics and substituted into the model to calculate the vibration response of the target focus point. The vibration characteristic distribution of the frame can be accurately obtained, thereby improving the vibration analysis effect of the air jet loom. (2) By using the least squares complex exponential method to solve the modal parameters and frequency response function of the motion mechanism of the jet loom, key information can be accurately extracted from the obtained free response, and accurate modal parameters and frequency response function can be obtained. This can more comprehensively reflect the dynamic characteristics of the motion mechanism and improve the accuracy of vibration analysis. (3) By establishing accurate vibration transmission models for the swing motion mechanism and the linear motion mechanism respectively, for the swing motion mechanism, a linear relationship is established between the acceleration frequency response function at the end of the frame and the nominal frequency response function of each swing joint; for the linear motion mechanism, a transmission model is established between the frequency domain displacement response of the frame and the frequency domain input of each linear motion mechanism, so that the vibration response of the frame can be accurately predicted. (4) In the process of frequency domain dynamic equation analysis of the frame, by introducing the diagonal compensation coefficient matrix of stiffness, damping and mass, as well as the displacement-related stiffness and damping correction matrix and nonlinear stiffness and damping matrix, the complex factors can be quantitatively described and compensated and corrected; thereby improving the accuracy of the vibration transmission model, and being able to more accurately describe the relationship between the frequency domain displacement response of the frame and the frequency domain input of the linear motion mechanism, thereby further improving the vibration analysis effect of the air jet loom. Attached Figure Description

[0016] 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.

[0017] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a first schematic diagram of the sensor installation position in the method of the present invention; Figure 3 This is a second schematic diagram showing the sensor installation position in the method of the present invention; Figure 4 This is a third schematic diagram showing the sensor installation position in the method of the present invention; Figure 5 This is a fourth schematic diagram showing the sensor installation position in the method of the present invention; Figure 6 This is a fifth schematic diagram showing the sensor installation position in the method of the present invention; Figure 7 This is a sixth schematic diagram showing the sensor installation position in the method of the present invention; Figure 8 This is a schematic diagram illustrating the feed speed law of the excitation source of the jet loom in the method of the present invention; Figure 9 This is a schematic diagram illustrating the law of inertial excitation force of the excitation source in the method of the present invention; Figure 10 This is a schematic diagram of the random no-run self-excited vibration response of the method of the present invention; Figure 11 This is a schematic diagram of the random no-run self-response of the method of the present invention; Figure 12 This is a schematic diagram of the dynamic characteristics of the air-jet loom, including the various motion mechanisms and frame of the air-jet loom according to the method of the present invention. Detailed Implementation

[0018] 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.

[0019] like Figure 1-12 As shown, the present invention provides a method for analyzing the vibration characteristics of an air-jet loom, comprising the following steps: S1 provides time-division independent excitation for multiple motion mechanisms of the air-jet loom and collects the frame vibration response signals under the excitation of each motion mechanism.

[0020] Step S1 includes the following sub-steps: S11, the air-jet loom includes a heald frame, a beating-off rocker, a warp loosening link, a tie rod, and a dynamic back beam motion mechanism, which sequentially and independently excites multiple motion mechanisms of the air-jet loom in a time-division manner; The control mechanism performs reciprocating acceleration and deceleration motion, accelerating it to a preset speed value, and then immediately reverses the acceleration until the speed drops to zero. After a random time interval, the acceleration and deceleration motion is repeated in the opposite direction, and the absolute value of the acceleration remains constant during the acceleration and deceleration motion. Through multiple alternating reciprocating acceleration and deceleration motions, the individual motion mechanism of the air-jet loom generates excitation force. It should be noted that the air-jet loom contains several key motion mechanisms, specifically including the heald frame, beat-up rocker, warp release link, tie rod, and dynamic back beam motion mechanism. When exciting these motion mechanisms, a time-sharing independent excitation method is adopted, that is, each motion mechanism is excited individually in sequence, ensuring that only one motion mechanism is excited at any given time. This avoids mutual interference between the excitations of multiple motion mechanisms, thereby accurately obtaining the impact of each motion mechanism on the frame vibration. For the excitation method of each motion mechanism, the motion mechanism is controlled to perform reciprocating acceleration and deceleration motion. The specific operation is as follows: First, the motion mechanism is accelerated to a preset speed value. The preset speed value is set according to the actual operating parameters of the air-jet loom and the experimental requirements to ensure that the excitation force can fully reflect the working characteristics of the motion mechanism. After the motion mechanism accelerates to the preset speed value, its acceleration is immediately reversed until the speed drops to zero. At this time, the motion mechanism completes one acceleration and deceleration process. After that, after a random time interval, the random time interval is set to simulate the uncertainty of the motion mechanism's action in actual operation, so that the excitation is closer to the real working condition. The above acceleration and deceleration motion process is repeated in the opposite direction. During the entire acceleration and deceleration motion process, the absolute value of the acceleration remains constant. Through multiple alternating reciprocating acceleration and deceleration motions, a stable and repeatable excitation force is generated for each motion mechanism of the air-jet loom. This excitation method can simulate the dynamic changes of the motion mechanism in actual work and can be regarded as a pulse excitation force. At the same time, the time interval between the pulse excitation forces is random, so the structure will generate a random pulse response, which effectively excites the vibration response of the frame.

[0021] S12 uses sensors arranged on the frame to collect vibration acceleration signals along the X, Y, and Z directions generated by the excitation of each motion mechanism, which are used as the frame vibration response signals under the excitation of the motion mechanism.

[0022] It should be noted that acceleration sensors are arranged at the motor, cam box, weft insertion mechanism, shedding mechanism, warp feeding mechanism, main shaft vibration source, passive ends of left and right wall panels, and loom response points. When the air-jet loom is running, vibration signals at different speeds are collected to obtain the vibration amplitude and frequency in the X, Y, and Z directions, and the root mean square value of vibration acceleration is calculated to evaluate the vibration state of the loom.

[0023] Specifically, an SCM2E05 LMS acquisition system and three piezoelectric accelerometers were used to acquire acceleration signals at a sampling frequency of 1024 Hz and a test frequency range of 0-512 Hz. Sensors were placed at various locations, including basic vibration sources such as motors and cams, moving vibration sources such as the weft insertion mechanism, shedding mechanism, and main shaft, passive ends such as the lower middle and lower middle sides of the left and right wall panels, and four evaluation reference points at the front and rear of the left and right wall panels, totaling 60 points. Under the operation of an ultra-high-speed air-jet loom, LMS software was used to monitor and record the vibration amplitude and frequency in the X, Y, and Z directions at different speeds of 500-1000 rpm. The root mean square value of the vibration acceleration was processed, calculated, and integrated. An example analysis was conducted using two motion mechanisms: the warp release link and the weft insertion rocker shaft. Figure 2 The sensor positions for obtaining the vibration response of each drive shaft of the air-jet loom are shown. The main criterion for sensor placement is to measure the tangential and radial vibration of the drive angle, and to place comparison sensors to facilitate data analysis later.

[0024] In this embodiment, by independently exciting multiple motion mechanisms of the air-jet loom and collecting the frame vibration response signals, the vibration response signals of the frame in three directions under independent excitation of each motion mechanism can be accurately obtained. This avoids the problem of mutual interference between multiple motion mechanism excitations, and enables the collected signals to truly reflect the influence of each motion mechanism on the frame vibration. Based on these accurate vibration response signals, the vibration characteristics of the air-jet loom can be analyzed in depth, and the key motion mechanisms that cause excessive vibration can be identified.

[0025] S2. For the vibration response signals of each motion mechanism under excitation, the free response of the corresponding motion mechanism is extracted by random subtraction method, and the modal parameters and frequency response functions of each motion mechanism under excitation are obtained by least squares complex exponential method.

[0026] For the vibration response of the motion mechanism, the stochastic decrement method is used to divide it into three parts: deterministic terms, free response, and stochastic excitation terms, and a vibration response model is constructed: ; In the formula, x represents the displacement of the vibration response, x(0) Displacement representing the initial time. Let be the velocity at time 0; D(t) be the velocity at the initial displacement x(0). =1, initial velocity The free response of a moving component of a jet loom under the action of x(0) reflects the inherent vibration characteristics of the motion mechanism itself under specific initial displacement conditions; v(t) is x(0). =0, =1 represents the free response of a certain moving component under the condition of action, reflecting the free vibration of the motion mechanism under a specific initial velocity condition; h(t) is the unit impulse response function of the motion mechanism, describing the response characteristics of the motion mechanism to a unit impulse input, which is obtained through convolution and integration. The contribution of the random excitation term to the vibration response can be calculated, where f ( t ) is the excitation signal; Step S2 involves extracting the free response of each motion mechanism from its vibration response signals under excitation using a random subtraction method, and includes the following sub-steps: S21, Set the displacement threshold A, and construct based on the displacement threshold. x = Threshold line of A; It should be noted that the displacement threshold A should be reasonably set based on the actual operating conditions of the air-jet loom and the amplitude range of the vibration response signal. This threshold should ensure that a sufficient number of effective intersections can be obtained from the vibration response signal, while avoiding setting the threshold too low, which would introduce too much noise interference, or setting it too high, which would prevent the acquisition of sufficient intersection information. A preliminary analysis of the collected vibration response signal can be performed to understand the approximate distribution of its amplitude, and then a value within a reasonable range can be selected as the displacement threshold A. The displacement threshold A should range from 1 / 2 to 2 / 3 of the acceleration response peak, with a coefficient α, where 1 / 2 ≤ α ≤ 2 / 3. The expression is: A threshold line for x=A is constructed, which will serve as a reference standard for extracting key information from the vibration response signal.

[0027] S22, obtain the intersection positions with the threshold line from the vibration response signal, and extract the time points corresponding to each intersection position; It should be noted that the constructed threshold line x=A is compared and analyzed with the acquired vibration response signal; the vibration response signal is a curve with time as the horizontal axis and displacement as the vertical axis; through numerical calculation methods, all intersection points of the vibration response signal curve and the threshold line x=A are found; for each intersection point, its corresponding time point is extracted as the starting time basis for subsequent signal segment extraction; when extracting time points, time accuracy needs to be ensured to reduce errors in subsequent processing.

[0028] S23, taking the time point corresponding to each intersection as the starting time, extracts a fixed-length signal from the vibration response signal to form a signal segment.

[0029] It should be noted that the length of the signal segment to be truncated should be determined according to actual needs. This length should be able to contain the main characteristic information of the free response of the motion mechanism, while avoiding truncating too long, which would contain too much irrelevant information, or truncating too short, which would lose key features. The time point corresponding to each intersection position is used as the starting time, and signal segments are truncated from the vibration response signal according to the determined fixed length. Each intersection point corresponds to one signal segment, resulting in multiple signal segments. These signal segments contain some vibration information of the motion mechanism at different starting times.

[0030] Using the signal segment of the vibration response as a sample, the vibration response of a single pulse excitation at time t is calculated based on the sample, and the expression is: ; In the formula, D(t): when x(0)=1, The homogeneous solution when x(0) = 0; satisfying D(0) = 1, D′(0) = 0; v(t): when x(0) = 0, The homogeneous solution when τ = 1 satisfies v(0) = 0, v′(0) = 1; where k = 1, 2, ..., N, and τ is a value greater than zero. h (t-τ) is the unit impulse response function of the motion mechanism; S24, align all signal segments on the time axis, and average the aligned signal segments to obtain the free response of the motion mechanism, expressed as: ; In the formula, D(t) is the free response of the motion mechanism, N is the number of intersection points, A is the displacement threshold, and t k Let t be the time point corresponding to the kth intersection point, and t be the time point from each starting time t. k The relative time variable to begin calculation, x(t+t) k The vibration response signal at time t+t k The amplitude.

[0031] It should be noted that, in order to accurately extract the free response of the motion mechanism, all captured signal segments need to be aligned on the time axis. Using the start time of each signal segment as a reference, subsequent time points are relativized so that all signal segments have the same starting reference point on the time axis. Then, all aligned signal segments are averaged, that is, the signal amplitudes at corresponding time points are added together and then divided by the number of signal segments N. Through this averaging process, random noise and other non-free response components in the vibration response signal can be effectively eliminated, highlighting the free response characteristics of the motion mechanism itself. The final average signal is the free response of the motion mechanism.

[0032] And thus, the free response of the motion mechanism at each moment is obtained, expressed as: ; In the formula, E[x(t+t)] k [)] represents the free response of the motion mechanism at each moment.

[0033] Based on the actual initial conditions, combined with the obtained free response at a specific initial velocity, the unit impulse response function, and the random excitation force, the vibration response of the motion mechanism at different times is calculated according to the vibration response model formula.

[0034] In this embodiment, the random subtraction method is used to extract the free response of the air jet loom's motion mechanism. This effectively eliminates random noise and other non-free response components in the vibration response signal, highlights the vibration characteristics of the motion mechanism itself, and makes the extracted free response signal more accurate, thus reflecting the working state and vibration characteristics of the motion mechanism more realistically.

[0035] Step S2, which involves using the least squares complex exponential method to solve for the modal parameters and frequency response function of the corresponding motion mechanism under excitation, includes the following sub-steps: S25, the free response of the motion mechanism is constructed as a discrete-time series, and a Hankel matrix H is constructed based on the discrete-time series. The expression of matrix H is: ; In the formula, let the discrete time series be {h1,h2,...,h...} M}, where M is the total number of samples in the response data, K is the number of columns in the Hankel matrix, and L is the number of rows in the Hankel matrix.

[0036] If we assume h m Let be the impulse response sequence of the system, representing the th... m The response value at time t, and assuming h m If a linear recurrence relation consisting of a finite number of complex exponential terms exists, then there exists a polynomial coefficient a. i This ensures that long sequences fully satisfy the following when noise is free: ; In the formula, a k The coefficients of the polynomial to be solved form the characteristic polynomial coefficient vector, h. m Let m represent the values ​​of the impulse response sequence at different times, where m represents the starting time and k represents the offset relative to the starting time. When the system is in a noise-free state, the system's impulse response sequence satisfies this specific linear recursive relationship. By constructing this linear recursive relationship and using the collected response data, the coefficient 'a' can be solved. i .

[0037] S26. Based on the Hankel matrix, an error function with the characteristic polynomial coefficient vector as the variable is defined. The characteristic polynomial coefficient vector that minimizes the error function is solved by the least squares complex exponential method. The error function is defined as J =2Ca, where C=H T H,a = [a 2N …a 0 ] T , where 'a' is the coefficient vector of the characteristic polynomial, by letting J Solving for 0, the least squares solution for the characteristic polynomial coefficient vector a is: .

[0038] It should be noted that this error function reflects the degree of error between the model constructed based on the Hankel matrix and the actual data. By using the least squares complex exponential method and setting J=0, the least squares solution of the characteristic polynomial coefficient vector a is obtained; the characteristic polynomial coefficient vector that minimizes the error function contains key information for subsequent solution of modal parameters.

[0039] S27. Construct the characteristic polynomial based on the coefficient vector of the characteristic polynomial and solve for the roots of the characteristic polynomial; calculate the complex frequency poles of the system based on the roots of the characteristic polynomial. The root of this characteristic polynomial is expressed as: ; In the formula, Z r s is the root of the polynomial r Here are the complex frequency poles of the system, and Δt is the sampling time interval; The complex frequency poles and conjugate poles of the system are obtained by calculating the roots of the characteristic polynomial, and the expression is: ; ; In the formula, s r α is the root of the characteristic polynomial, Δt is the sampling time interval, and α is the root of the characteristic polynomial. r β is the real part of the complex frequency pole of the system. r Let j be the imaginary part of the complex frequency poles of the system, and j be the imaginary unit. S28, based on the real and imaginary parts of the complex frequency poles of the system, calculate the modal frequencies and damping ratios of the corresponding motion mechanism under excitation, as expressed in the following expressions: ; ; In the formula, ω r ξ is the modal frequency; r The damping ratio is denoted as .

[0040] The above calculations yield the modal frequencies and damping ratios corresponding to each mode, reflecting the vibration frequencies and energy dissipation characteristics of the motion mechanism at different orders.

[0041] S29. Based on the amplitude vector corresponding to the complex frequency poles of the system, extract the mode shape of the system, and combine the mode frequency, damping ratio and mode shape to obtain the frequency response function under the excitation of the corresponding motion mechanism.

[0042] By taking different values ​​for the model calculation order, the corresponding modal frequencies and damping ratios at different orders can be calculated. With the modal frequencies and damping ratios as the abscissa and the calculation order as the ordinate, steady-state diagrams of the modal frequencies and damping ratios are plotted respectively. The frequencies that appear in each order can be considered as modal frequencies.

[0043] In this embodiment, the least squares complex exponential method is used to solve the modal parameters and frequency response function of the air jet loom motion mechanism. This method can accurately extract key information from the obtained free response to obtain precise modal parameters and frequency response function. The modal parameters and frequency response function obtained by this method can more comprehensively reflect the dynamic characteristics of the motion mechanism and improve the accuracy of vibration analysis.

[0044] S3. Based on the type of motion mechanism, establish vibration transmission models between frame vibration response and motion mechanism excitation. The types of motion mechanisms include oscillating motion and linear motion. Based on the swing motion mechanism, the relationship between the frequency response function of the acceleration at the end of the frame and the nominal frequency response function of each swing joint is established. Analysis of the oscillating motion mechanism: Under a fixed orientation, the frame frequency response function can be calculated from the three transmission angles in the oscillating motion mechanism of the air-jet loom. In this case, the frame frequency response function is analyzed within the transmission space, with the variables being each transmission angle. f i To analyze frame vibration, the variables need to be transformed into frame vibration, i.e., XYZ and redundancy angles. For a given frame vibration position, the inverse kinematics of the air-jet loom is used to calculate the various transmission angles of the air-jet loom under this vibration state, and then the following calculations are performed. H x Then, by combining the frequency response functions of each mechanism, the positional distribution of the frame frequency response function on the frame is obtained.

[0045] Includes the following sub-steps: S311, the beat-up rocker motion mechanism has three swing joints. Based on the transmission equations of an air-jet loom, the kinematic parameters of the beat-up rocker motion mechanism are determined, including the rotational speed ξ=[ξ1,ξ2,ξ3] of each swing joint. T and the corresponding joint transmission angle i =[ i 1, i 2, i 3] T ; It should be noted that the transmission model analyzed using the rocker mechanism as an example is as follows: the main shaft of the crank-rocker mechanism is connected to the crankshaft, and the crankshaft is connected to the rocker. During the movement, the crank-rocker mechanism will drive the mechanism to make slight movements. There are three transmission angles in the entire transmission process. According to the transmission of the air-jet loom, the movement vector of the swinging component 1 is ω1, the origin vector of the coordinate system is r1, the movement vector of the swinging component 2 is ω2, the origin vector of the coordinate system is r2, and the movement vector of the swinging component 3 is ω3, the origin vector of the coordinate system is r3. ; The rotational motion of each pivot joint is ξ = [ξ1, ξ2, ξ3]. T The expression is: ; The initial pose of the mechanism is: ; S312, based on the rotational motion of the three swing joints and the joint transmission angle vectors, establish a kinematic model between the end-frame pose and the transmission angles of each swing joint, expressed as: ; In the formula, These are the antisymmetric matrix operators corresponding to the spinors of the three joint motions, respectively. p 0 represents the initial pose of the rack. i 1, i 2, i 3 represents the transmission angle vectors of the three joints; Analyze one of the directions to p x For example, (φ): ; In the formula, f x1 (φ1) is the pose component related to the transmission angle φ1; f x2 (φ1) represents the number of coefficients related to the expected joint angle φ1; h x1 (φ2) is a coefficient related to the transmission angle φ2; S313, by taking the second derivative of the kinematic model and performing a Fourier transform, a linear relationship is established between the frequency response function of the frame end acceleration and the nominal frequency response functions of each swing joint, resulting in a vibration transmission model for the swing motion type, expressed as: ; ; In the formula, oh 2 Ix ( oh ) represents the frequency response function of the rack end effector, describing the acceleration response characteristics of the rack end effector to excitation in the frequency domain. Vec(·) is the matrix vectorization operator used to convert a matrix into a vector form. T x Let be the second-order partial derivative matrix of the frame pose with respect to the transmission angle, reflecting the second-order sensitivity of the frame pose to changes in the joint transmission angle. H i (ω) is the convolutional combination matrix of the joint frequency responses, which comprehensively considers the mutual influence and combination relationship between the frequency responses of each joint. T θ The matrix Φ( is the second-order partial derivative of the frame end pose with respect to the transmission angle;) oh ) represents the nominal frequency response function vector of each swing joint, Φ( oh =[Φ1(ω),Φ2(ω),Φ3(ω)] T These are key parameters that describe the vibration characteristics of a joint itself.

[0046] The vibration transmission model based on the swing motion mechanism established in this embodiment can accurately describe the linear relationship between the acceleration frequency response function at the end of the frame and the nominal frequency response function of each swing joint, providing an effective theoretical basis for in-depth analysis of the vibration characteristics of the frame under the excitation of the swing motion mechanism of the air jet loom.

[0047] Based on linear motion mechanisms, the relationship between the frame frequency domain displacement response and the inputs of each mechanism is established based on the kinematic Jacobian matrix. Includes the following sub-steps: S321, the linear motion mechanism includes a heald frame motion mechanism, a loosening linkage motion mechanism, and a pull rod motion mechanism. The heald frame motion mechanism moves in the vertical direction, and the loosening linkage motion mechanism moves at an angle to the horizontal direction. ϕ Angle motion; the linkage mechanism moves in the left and right directions; obtain the displacement vectors of the heald frame mechanism, the loosening linkage mechanism, and the linkage mechanism respectively; S322, Based on the displacement vectors and included angles of the heald frame motion mechanism, the loosening linkage motion mechanism and the tie rod motion mechanism, establish the composite displacement vector of the frame in the fixed plane coordinate system; Wherein, the fixed coordinate system of the frame is set as ; The combined displacement of the frame is: ; ; ; In the formula, g ( t () represents the resultant displacement of the frame in the plane.x s2(t) is the displacement vector of the pull rod mechanism; s3(t) is the displacement vector of the release rod mechanism; y 1(t) is the displacement vector of the heald frame mechanism; S323. Differentiate the composite displacement vector to establish the kinematic relationship between the frame acceleration and each linear motion mechanism, and perform a Fourier transform to convert it to the frequency domain to obtain the relationship between the frame acceleration frequency response and the displacement frequency response of each linear motion mechanism. The rack linear velocity is obtained by differentiating the composite displacement vector with respect to timing. ; Taking the derivative with respect to time, we can obtain the frame acceleration: ; Fourier transform of the frame acceleration: ; In the formula, For Fourier transform, For rack acceleration, J ( q ) is the kinematic Jacobian matrix; Q ( oh ) represents the displacement frequency domain response of each linear mechanism. Q ( oh )=[ Y 1( oh ), X 2( oh ),S3( oh )] T , Y 1( oh ( ) represents the displacement frequency domain response of the heald frame mechanism. X 2( oh S3 is the displacement frequency domain response of the linkage mechanism. oh The displacement frequency domain response of the linkage mechanism is given. oh Angular velocity; S324, combining the frequency domain dynamic equations of the frame, derives and establishes a vibration transmission model between the frequency domain displacement response of the frame and the frequency domain input of each linear motion mechanism.

[0048] Includes the following steps: S3241, Establish the frequency domain dynamic equations of the rack, the expression is: ; In the formula, F(ω) is the excitation vector of the linear mechanism on the frame, I is the identity matrix, ΛK is the diagonal compensation coefficient matrix of stiffness, ΛC is the diagonal compensation coefficient matrix of damping, ΛM is the diagonal compensation coefficient matrix of mass; G(ω) is the frequency domain displacement response of the frame. M is the rack equivalent mass matrix; Here is the overall stiffness matrix of the frame; This represents the total damping matrix of the rack. The expression for the overall stiffness matrix of the frame is: ; In the formula, K0 is the initial linear stiffness matrix of the frame, and ΔK(q) is the displacement-dependent stiffness correction matrix. It is a nonlinear stiffness matrix; ΛK is the diagonal compensation coefficient matrix for stiffness, expressed as: ; In the formula, λ K,xx , λ K,yy , λ K,zz These are the compensation coefficients for stiffness in the x, y, and z directions, respectively.

[0049] K0 is the initial linear stiffness matrix of the frame, expressed as: ; In the formula, the diagonal element K 0,xx K 0,yy K 0,zz These represent the principal stiffnesses in the x, y, and z directions, respectively, while the off-diagonal elements represent the cross stiffnesses between these directions.

[0050] ΔK is the displacement-dependent stiffness correction matrix, expressed as: ; In the formula, k x , k y , k z These are the stiffness displacement correction factors in the x, y, and z directions, respectively.

[0051] K nl The nonlinear stiffness matrix is ​​expressed as: ; In the formula, K gap,x , K gap,y , K gap,z These are the stiffnesses after gap contact in the x, y, and z directions, respectively. d x , d y , d z These represent the gap values ​​in the x, y, and z directions, respectively; Θ is the step function. j It is the imaginary unit.

[0052] The expression for the total damping matrix of the rack is: ; In the formula, C0 is the initial linear damping matrix of the frame, and ΔC(q) is the displacement-dependent damping correction matrix. It is a nonlinear damping matrix; C0 is the initial linear damping matrix of the rack, expressed as: ; In the formula, the diagonal element C 0,xx C 0,yy C 0,zz The main damping elements are the x, y, and z directions, respectively; the off-diagonal elements are the cross damping elements between each direction.

[0053] ΔC is the displacement-dependent damping correction matrix, expressed as: ; In the formula, c x c y c z These are the coefficients of damping in the x, y, and z directions, respectively, as a function of the corresponding mechanism speed.

[0054] C nl The nonlinear damping matrix is ​​expressed as follows: ; In the formula, C coul,x C coul,y C coul,z are the Coulomb friction coefficients in the x, y, and z directions, respectively, and sgn(·) is the sign function in the velocity direction; Where M is the rack equivalent mass matrix, and its matrix expression is: ;

[0055] In the formula, m xx m yy m zz These are the equivalent masses in the x, y, and z directions, respectively.

[0056] q=[y1,x2,s3] T , where is the displacement vector of the three mechanisms.

[0057] Define the dynamic stiffness matrix Z(ω): ; Define the compensated frequency response function matrix H(ω,q): F(ω)=Z(ω)G(ω); H(ω,q)=Z(ω) -1 ; ; H(ω)F(ω)=G(ω); In the formula, H(ω,q) is the equivalent frequency response function matrix of the frame; During actual operation, the dynamic characteristics of the frame of an air-jet loom are affected by a variety of complex factors, such as material inhomogeneity, minute gaps in the connection parts, and nonlinear damping characteristics. By introducing diagonal compensation coefficient matrices for stiffness, damping, and mass, as well as displacement-related stiffness and damping correction matrices and nonlinear stiffness and damping matrices, these complex factors can be quantitatively described and compensated for in detail. This makes the frequency domain dynamic equations of the frame closer to the actual situation, thereby improving the accuracy of the established vibration transmission model and enabling a more accurate description of the relationship between the frequency domain displacement response of the frame and the frequency domain input of the linear motion mechanism.

[0058] S3242, based on the frequency domain dynamic equation of the frame and the relationship between the frame acceleration frequency response and the displacement frequency response of each linear motion mechanism, derive and establish the vibration transmission model between the frame frequency domain displacement response and the frequency domain input of each linear motion mechanism; Combining the coupling relationship between the mechanism displacement and the frame displacement, F(ω) corresponds to the excitation of the mechanism on the frame, which is equivalent to the excitation of J(q)Q(ω) after dynamic transmission. Finally, the following expression is obtained: .

[0059] It should be noted that by establishing a vibration transmission model between the frame frequency domain displacement response and the frequency domain input of each linear motion mechanism, the influence of the linear motion mechanism excitation on the frame displacement response in the frequency domain can be accurately described, providing an effective theoretical basis for analyzing the vibration characteristics of the frame under the excitation of the linear motion mechanism of the air jet loom.

[0060] S4. Based on the preset target focus point on the frame, the inverse kinematics of the air-jet loom is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular space coordinate system, and the vibration characteristic distribution of the air-jet loom frame is obtained.

[0061] It should be noted that a target focus point is preset on the frame, specifying the desired target position of this point in a Cartesian coordinate system. This target position is set according to the actual working requirements of the loom and the focus of vibration analysis, such as the location of a critical vibration-sensitive component on the frame. Based on the kinematic model of the air-jet loom, an inverse kinematics algorithm is used for solution. The inverse kinematics algorithm calculates the motion parameters of each motion mechanism when the end of the frame reaches the target position, based on the target position to be reached at the end of the frame. The motion parameters include the transmission angle of the swing joint, the displacement and velocity of the linear motion mechanism, etc. For each motion mechanism, its frequency response function is obtained based on the previously established vibration transmission model. The frequency response function describes the response characteristics of the motion mechanism to excitation in the frequency domain. The motion parameters and corresponding frequency response functions of each motion mechanism obtained by solving inverse kinematics are substituted into the corresponding vibration transmission model. For the oscillating motion mechanism, the vibration transmission model based on oscillating motion is substituted; for the linear motion mechanism, the vibration transmission model based on linear motion is substituted. Through mathematical operations and frequency domain analysis in the model, the vibration response of the target point of interest in the Cartesian coordinate system is calculated. The vibration response includes displacement response, velocity response, and acceleration response, etc., to comprehensively reflect the vibration state of the target point of interest.

[0062] Multiple target points of interest are preset on the frame. The inverse kinematics solution and vibration response calculation process described above are repeated to obtain the vibration response of each target point of interest. Based on the vibration response data of multiple target points of interest, the vibration characteristic distribution of the air-jet loom frame is analyzed. Vibration displacement cloud map, velocity cloud map or acceleration cloud map of the frame are plotted to visually display the vibration magnitude and distribution at different positions of the frame. Alternatively, statistical analysis methods can be used to determine the main frequency components of the frame vibration, the distribution range of vibration amplitude, etc., to provide a basis for further analysis of the causes of vibration and the formulation of vibration control strategies.

[0063] This embodiment can accurately obtain the vibration response of the target focus point of the frame in the rectangular coordinate system and comprehensively obtain the vibration characteristic distribution of the air-jet loom frame, which is conducive to a deeper understanding of the vibration law of the frame during the operation of the loom and to identifying areas with large vibration and key influencing factors.

[0064] Secondly, the present invention also provides a vibration characteristic analysis system for an air-jet loom, implemented using an air-jet loom vibration characteristic analysis method, comprising: The data acquisition module is used to independently excite multiple motion mechanisms of the air-jet loom in a time-division manner and to collect the frame vibration response signal under the excitation of each motion mechanism; The identification module is used to extract the free response of the corresponding motion mechanism from the vibration response signal under the excitation of each motion mechanism using the random subtraction method, and to identify the modal parameters and frequency response function of each motion mechanism under the excitation using the least squares complex exponential method. The model building module is used to establish vibration transmission models between frame vibration response and motion mechanism excitation according to the type of motion mechanism. The types of motion mechanisms include oscillating motion and linear motion. Based on the oscillating motion mechanism, the relationship between the frequency response function of the frame end acceleration and the nominal frequency response function of each oscillating joint is established. Based on the linear motion mechanism, the relationship between the frame frequency domain displacement response based on the kinematic Jacobian matrix and the input of each mechanism is established. The distribution generation module is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position by solving the inverse kinematics of the air-jet loom based on the preset target focus point on the frame. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular coordinate system and obtain the vibration characteristic distribution of the air-jet loom frame.

[0065] It should be noted that this system corresponds to the above-mentioned method for analyzing the vibration characteristics of 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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 well-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 described method or apparatus. In other words, 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.

[0074] 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 analyzing the vibration characteristics of an air-jet loom, characterized in that, Includes the following steps: S1, performs time-division independent excitation on multiple motion mechanisms of the air-jet loom, and collects the frame vibration response signal under the excitation of each motion mechanism; S2, for the vibration response signals of each motion mechanism under excitation, the free response of the corresponding motion mechanism is extracted by random subtraction method, and the modal parameters and frequency response functions of each motion mechanism under excitation are obtained by least squares complex exponential method. S3. Based on the type of motion mechanism, establish vibration transmission models between frame vibration response and motion mechanism excitation respectively; The types of motion mechanisms include swing motion and linear motion. Based on the swing motion mechanism, the relationship between the frequency response function of the frame end acceleration and the nominal frequency response function of each swing joint is established. Based on linear motion mechanisms, the relationship between the frame frequency domain displacement response and the inputs of each mechanism is established based on the kinematic Jacobian matrix. S4. Based on the preset target focus point on the frame, the inverse kinematics of the air-jet loom is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular space coordinate system, and the vibration characteristic distribution of the air-jet loom frame is obtained.

2. The method for analyzing the vibration characteristics of an air-jet loom as described in claim 1, characterized in that, Step S1, which involves independently exciting multiple motion mechanisms of the air-jet loom in a time-division manner and collecting the frame vibration response signal under the excitation of each motion mechanism, includes the following sub-steps: S11, the air-jet loom includes a heald frame, a beating-off rocker, a warp loosening link, a tie rod, and a dynamic back beam motion mechanism, which sequentially and independently excites multiple motion mechanisms of the air-jet loom in a time-division manner; The control mechanism performs reciprocating acceleration and deceleration motion, accelerating it to a preset speed value, and then immediately reverses the acceleration until the speed drops to zero. After a random time interval, the acceleration and deceleration motion is repeated in the opposite direction, and the absolute value of the acceleration remains constant during the acceleration and deceleration motion. Through multiple alternating reciprocating acceleration and deceleration motions, the individual motion mechanism of the air-jet loom generates excitation force. S12 uses sensors arranged on the frame to collect vibration acceleration signals along the X, Y, and Z directions generated by the excitation of each motion mechanism, which are used as the frame vibration response signals under the excitation of the motion mechanism.

3. The method for analyzing the vibration characteristics of an air-jet loom as described in claim 2, characterized in that: Step S2 involves extracting the free response of each motion mechanism from its vibration response signal under excitation using a random subtraction method, and includes the following sub-steps: S21, Set the displacement threshold A, and construct based on the displacement threshold. x = Threshold line of A; S22, obtain the intersection positions with the threshold line from the vibration response signal, and extract the time points corresponding to each intersection position; S23, taking the time point corresponding to each intersection as the starting time, extract a fixed-length signal from the vibration response signal to form a signal segment; S24, align all signal segments on the time axis, and average the aligned signal segments to obtain the free response of the motion mechanism.

4. The vibration characteristic analysis method for an air-jet loom as described in claim 3, characterized in that: Step S2, which involves using the least squares complex exponential method to solve for the modal parameters and frequency response function of the corresponding motion mechanism under excitation, includes the following sub-steps: S25, construct the free response of the motion mechanism as a discrete time series, and construct the Hankel matrix H based on the discrete time series; S26. Based on the Hankel matrix, an error function with the characteristic polynomial coefficient vector as the variable is defined. The characteristic polynomial coefficient vector that minimizes the error function is solved by the least squares complex exponential method. S27. Construct the characteristic polynomial based on the coefficient vector of the characteristic polynomial, and solve for the roots of the characteristic polynomial. The complex frequency poles of the system are obtained by calculating the roots of the characteristic polynomial. S28. Calculate the modal frequencies and damping ratios of the corresponding motion mechanism under excitation based on the real and imaginary parts of the complex frequency poles of the system. S29. Based on the amplitude vector corresponding to the complex frequency poles of the system, extract the mode shape of the system, and combine the mode frequency, damping ratio and mode shape to obtain the frequency response function under the excitation of the corresponding motion mechanism.

5. The vibration characteristic analysis method for an air-jet loom as described in claim 4, characterized in that: The error function is defined as J =2Ca, where C=H T H,a = [a 2N …a 0 ] T , where 'a' is the coefficient vector of the characteristic polynomial, by letting J Solving for 0, the least squares solution for the characteristic polynomial coefficient vector a is: 。 6. The method for analyzing the vibration characteristics of an air-jet loom as described in claim 5, characterized in that: Step S3, which establishes the relationship between the acceleration frequency response function at the end of the frame and the nominal frequency response function of each swing joint based on the swing motion mechanism, includes the following sub-steps: S311, the beat-up rocker motion mechanism has three swing joints. Based on the transmission equations of the air-jet loom, the kinematic parameters of the beat-up rocker motion mechanism are determined, including the rotational speed ξ=[ξ1,ξ2,ξ3] of each swing joint. T and the corresponding joint transmission angle θ =[ θ 1, θ 2, θ 3] T ; S312, based on the rotational motion of the three swing joints and the joint transmission angle vectors, establish a kinematic model between the end-frame pose and the transmission angles of each swing joint, expressed as: ； In the formula, These are the antisymmetric matrix operators corresponding to the spinors of the three joint motions, respectively. p 0 represents the initial pose of the rack. θ 1, θ 2, θ 3 represents the transmission angle vectors of the three joints; S313, by taking the second derivative of the kinematic model and performing a Fourier transform, a linear relationship is established between the frequency response function of the frame end acceleration and the nominal frequency response functions of each swing joint, resulting in a vibration transmission model for the swing motion type, expressed as: ； In the formula, ω 2 I x ( ω Let Vec(·) be the frequency response function of the acceleration at the end of the rack, and Vec(·) be the matrix vectorization operator. T x Let be the second-order partial derivative matrix of the frame pose with respect to the transmission angle. H i (ω) is the convolution combination matrix of the joint frequency response. T θ The matrix represents the second-order partial derivative of the frame end pose with respect to the transmission angle. Φ( ω ) represents the nominal frequency response function vector of each swing joint, Φ( ω =[Φ1(ω),Φ2(ω),Φ3(ω)] T .

7. The vibration characteristic analysis method for an air-jet loom as described in claim 6, characterized in that: Step S3, which establishes the relationship between the frame frequency domain displacement response and the inputs of each mechanism based on the kinematic Jacobian matrix, includes the following sub-steps: S321, the linear motion mechanism includes a heald frame motion mechanism, a loosening link motion mechanism, and a connecting rod motion mechanism. The heald frame motion mechanism moves in the vertical direction, and the loosening link motion mechanism moves at an angle to the horizontal direction. ϕ Angle motion; the linkage mechanism moves in the left and right directions; obtain the displacement vectors of the heald frame mechanism, the loosening linkage mechanism, and the linkage mechanism respectively; S322, based on the displacement vectors and included angles of the heald frame motion mechanism, the loosening linkage motion mechanism, and the tie rod motion mechanism, establish the composite displacement vector of the frame in the fixed plane coordinate system, expressed as: ； In the formula, g ( t () represents the resultant displacement of the frame in the plane. x s2(t) is the displacement vector of the pull rod mechanism; s3(t) is the displacement vector of the release rod mechanism; y 1(t) is the displacement vector of the heald frame mechanism; S323, differentiate the composite displacement vector to establish the kinematic relationship between the frame acceleration and each linear motion mechanism, and perform a Fourier transform to convert it to the frequency domain to obtain the relationship between the frame acceleration frequency response and the displacement frequency response of each linear motion mechanism. The expression is: ； In the formula, For Fourier transform, For rack acceleration, J ( q ) is the kinematic Jacobian matrix; Q ( ω ) represents the displacement frequency domain response of each linear mechanism. Q ( ω )=[ Y 1( ω ), X 2( ω ),S3( ω )] T , Y 1( ω ( ) represents the displacement frequency domain response of the heald frame mechanism. X 2( ω S3 is the displacement frequency domain response of the linkage mechanism. ω The displacement frequency domain response of the linkage mechanism is given. ω Angular velocity; S324, combining the frequency domain dynamic equations of the frame, derives and establishes a vibration transmission model between the frequency domain displacement response of the frame and the frequency domain input of each linear motion mechanism.

8. The method for analyzing the vibration characteristics of an air-jet loom as described in claim 7, characterized in that: Step S324, which involves deriving and establishing a vibration transmission model between the frame's frequency domain displacement response and the frequency domain inputs of each linear motion mechanism, based on the frame's frequency domain dynamic equations, includes the following steps: S3241, Establish the frequency domain dynamic equations of the rack, the expression is: ； In the formula, F(ω) is the excitation vector of the linear mechanism on the frame, I is the identity matrix, ΛK is the diagonal compensation coefficient matrix of stiffness, ΛC is the diagonal compensation coefficient matrix of damping, ΛM is the diagonal compensation coefficient matrix of mass; G(ω) is the frequency domain displacement response of the frame. M is the rack equivalent mass matrix; Here is the overall stiffness matrix of the frame; This represents the total damping matrix of the rack. The expression for the overall stiffness matrix of the frame is: ； In the formula, K0 is the initial linear stiffness matrix of the frame, and ΔK(q) is the displacement-dependent stiffness correction matrix. It is a nonlinear stiffness matrix; The expression for the total damping matrix of the rack is: ； In the formula, C0 is the initial linear damping matrix of the frame, and ΔC(q) is the displacement-dependent damping correction matrix. It is a nonlinear damping matrix; S3242, based on the frequency domain dynamic equations of the frame and the relationship between the frame's acceleration frequency response and the displacement frequency response of each linear motion mechanism, a vibration transmission model between the frame's frequency domain displacement response and the frequency domain input of each linear motion mechanism is derived and established. The expression is: ； ； In the formula, H( ω ) is the equivalent frequency response function matrix of the rack.

9. A vibration characteristic analysis system for an air-jet loom, implemented using the vibration characteristic analysis method for an air-jet loom as described in any one of claims 1-8, characterized in that, include: The data acquisition module is used to independently excite multiple motion mechanisms of the air-jet loom in a time-division manner and to collect the frame vibration response signal under the excitation of each motion mechanism; The identification module is used to extract the free response of the corresponding motion mechanism from the vibration response signal under the excitation of each motion mechanism using the random subtraction method, and to identify the modal parameters and frequency response function of each motion mechanism under the excitation using the least squares complex exponential method. The model building module is used to establish vibration transmission models between frame vibration response and motion mechanism excitation according to the type of motion mechanism. The types of motion mechanisms include swing motion and linear motion. Based on the swing motion mechanism, the relationship between the frequency response function of the frame end acceleration and the nominal frequency response function of each swing joint is established. Based on linear motion mechanisms, the relationship between the frame frequency domain displacement response and the inputs of each mechanism is established based on the kinematic Jacobian matrix. The distribution generation module is used to obtain the motion parameters of each motion mechanism when the end of the frame reaches the target position by solving the inverse kinematics of the air-jet loom based on the preset target focus point on the frame. The motion parameters of each motion mechanism and the frequency response function of the corresponding motion mechanism are substituted into the corresponding vibration transmission model to calculate the vibration response of the target focus point in the rectangular coordinate system and obtain the vibration characteristic distribution of the air-jet loom frame.

10. A computer-readable storage medium, characterized in that, The storage medium stores a method program for analyzing the vibration characteristics of an air-jet loom, which, when executed, implements the method for analyzing the vibration characteristics of an air-jet loom as described in any one of claims 1 to 8.

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