Spunlace non-woven fabric intelligent rewinding control method and system

Abstract

The application discloses a kind of intelligent rewinding control methods of spunlace nonwoven fabric, belong to control technical field.The method includes: the attenuation duration of the charge carried by spunlace nonwoven fabric in rewinding process is determined to determine real-time tension, specifically including obtaining the charge attenuation data when cloth surface passes through measuring point, determine the attenuation duration experienced by the charge amount from initial monitoring value to preset charge value, then attenuation duration is compared with the first mapping data table to obtain real-time tension;Afterwards, based on real-time tension, determine the electrostatic field intensity applied to the surface of rewinding roller, and control the output voltage of high-voltage power supply according to the electrostatic field intensity.The application utilizes the attenuation characteristics of residual charge of spunlace fabric itself to realize non-contact tension measurement, and directly adjusts tension through electrostatic force, completely avoids mechanical contact, has the advantages of fast response speed, does not damage cloth surface, improves the intelligent level of rewinding control.

Description

Technical Field

[0001] This application relates to the field of control technology, and in particular to a method and system for intelligent rewinding control of spunlace nonwoven fabric. Background Technology

[0002] After production, spunlace nonwoven fabrics require a rewinding process to cut large rolls into smaller rolls or rewind them into finished rolls that meet specifications. During the rewinding process, precise tension control directly affects the flatness, tightness, and subsequent processing performance of the product.

[0003] Currently, tension control in rewinding machines generally employs a combination of contact measurement and mechanical adjustment. At the measurement end, floating rollers, tension levers, and angle sensors are typically used in conjunction, or load cells are directly installed on the fabric path to indirectly or directly obtain tension by detecting mechanical displacement or pressure. At the adjustment end, tension is adjusted by changing the speed and torque of the unwinding or rewinding motors. However, in this contact-based approach, continuous friction between the sensor and the fabric surface can easily cause fiber fuzzing, scratches, or even breakage, which is particularly detrimental to soft spunlace nonwoven fabrics. The inertia and clearance of the mechanical transmission chain lead to response lag, making it difficult to adapt to high-speed rewinding and sudden tension fluctuations. Furthermore, wear and tear on the mechanical structure after long-term operation also reduces control accuracy and stability. Summary of the Invention

[0004] This application provides a method and system for intelligent rewinding control of spunlace nonwoven fabric to improve the above-mentioned problems.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] In a first aspect, embodiments of this application propose an intelligent rewinding control method for spunlace nonwoven fabric, applied to an intelligent rewinding control system for spunlace nonwoven fabric. The system includes an electrostatic sensor, a rewinding roller, a high-voltage power supply disposed on the rewinding roller, and a control terminal. The method is executed by the control terminal and includes: determining the real-time tension of the spunlace nonwoven fabric based on the attenuation time of the charge carried by the spunlace nonwoven fabric during the rewinding process. This includes: acquiring attenuation data of the charge quantity of the spunlace nonwoven fabric changing over time as it passes through a measurement point based on the electrostatic sensor; determining the time taken for the charge quantity to attenuate from the initial monitoring value to a preset charge value from the attenuation data as the attenuation time; comparing the attenuation time with a preset first mapping data table to determine the real-time tension corresponding to the attenuation time; determining the electrostatic field strength applied to the surface of the rewinding roller based on the real-time tension; and controlling the output voltage of the high-voltage power supply based on the electrostatic field strength.

[0007] Therefore, the method proposed in this application obtains real-time tension by measuring the decay time of the surface charge of the spunlace nonwoven fabric, and controls the electrostatic field strength on the surface of the rewinding roller based on the real-time tension, thereby adjusting the rewinding tension in a non-contact manner. This method replaces traditional mechanical tension detection and adjustment methods, eliminates frictional damage between the sensor and the fabric surface, and features fast electrostatic field-driven response speed with no mechanical inertia, thus improving the response speed and non-destructive level of tension control.

[0008] In conjunction with the first aspect, optionally, determining the intensity of the electrostatic field applied to the surface of the rewinding roll based on the real-time tension includes: comparing the real-time tension with the target tension to obtain the deviation; and looking up the corresponding electrostatic field intensity from a preset second mapping data table based on the deviation.

[0009] Therefore, by using the deviation between the real-time tension and the target tension as an index to directly look up the corresponding electrostatic field strength in the second mapping data table, the required control output can be quickly determined, reducing the complexity of online calculations and ensuring the real-time performance and stability of tension adjustment.

[0010] In conjunction with the first aspect, optionally, the first mapping data is established by the following method: cutting spunlace nonwoven fabrics from the same batch into calibration samples and fixing the calibration samples in a calibration device, wherein the calibration device includes an application electrode plate and a ground electrode plate arranged in parallel, and the calibration samples are located between the application electrode plate and the ground electrode plate; outputting multiple calibration voltages of known amplitude to the application electrode plate, so that the calibration samples are subjected to multiple corresponding known electrostatic forces, wherein each known electrostatic force is equivalent to a known calibration tension; obtaining the time for the charge of the calibration samples corresponding to each known calibration tension to decay from the initial monitoring value to the preset charge value, and determining it as the calibration decay time; pairing the known calibration tension with the corresponding calibration decay time to form a first mapping data table.

[0011] Therefore, when establishing the first mapping data table, the calibration sample cloth of the same batch as the online measurement is used, and the known electrostatic force is applied by means of parallel electrode plates to equivalently calibrate the tension, so that the calibration environment is consistent with the electrostatic field action mode in the actual rewinding condition, thereby ensuring the accuracy of the mapping relationship between decay time and tension and avoiding the error introduced by the difference in working conditions.

[0012] In conjunction with the first aspect, optionally, the second mapping data is established as follows: while the spunlace nonwoven fabric is rewound at a uniform speed and under target tension, the high-voltage power supply outputs a test voltage to generate a test electrostatic field with a step increase on the surface of the rewinding roller; during the action of the test electrostatic field, the change in charge decay time of the spunlace nonwoven fabric is acquired, and the change in charge decay time is converted into a tension response curve based on the first mapping data table; the tension peak and settling time are identified from the tension response curve, and the mapping relationship between the electrostatic field strength and the tension deviation is determined based on the offset of the tension peak relative to the target tension and the step amplitude of the test electrostatic field strength; multiple sets of data are obtained based on multiple different step amplitudes of the test voltage, thereby generating the second mapping data table.

[0013] Therefore, when establishing the second mapping data table, the dynamic response of tension is obtained by applying a step test electrostatic field under normal operating conditions. This allows for online identification of the correspondence between the electrostatic field strength and the tension deviation under the current working conditions, enabling the control mapping to automatically follow changes in materials, speed, etc., thus ensuring the long-term effectiveness of the control model.

[0014] In conjunction with the first aspect, optionally, the method further includes: acquiring the real-time travel speed of the spunlace nonwoven fabric at the measurement point; determining a speed fluctuation sequence based on the real-time travel speed, and acquiring the speed peak value and corresponding first timestamp in the speed fluctuation sequence; determining an attenuation duration fluctuation sequence based on the attenuation duration, and acquiring the attenuation duration extreme value and corresponding second timestamp in the attenuation duration fluctuation sequence; comparing the first timestamp and the second timestamp within the same time period to determine the time difference; determining that the fluctuation of the attenuation duration is caused by the fluctuation of the real-time travel speed when the absolute value of the time difference is less than a preset time association threshold; determining a coupling coefficient based on the amplitude ratio between the speed peak value and the attenuation duration extreme value; converting the fluctuation amount of the real-time travel speed into an attenuation duration compensation amount based on the coupling coefficient; subtracting the attenuation duration compensation amount from the current attenuation duration to obtain the compensated attenuation duration; and determining the real-time tension based on the compensated attenuation duration and the first mapping data table.

[0015] Therefore, by detecting fluctuations in real-time travel speed and attenuation time, and using timestamp comparison to identify interference events caused by speed, the coupling coefficient can be determined and the attenuation time can be compensated. This effectively removes crosstalk from speed fluctuations to tension measurement and improves the purity and reliability of the tension signal.

[0016] In conjunction with the first aspect, optionally, the coupling coefficient is determined based on the amplitude ratio between the peak velocity and the extreme value of the decay duration, including: obtaining the peak velocity and the corresponding extreme value of decay duration in multiple different time periods; obtaining the amplitude ratio of each pair of peak velocity and extreme value of decay duration to obtain multiple amplitude ratio samples; removing samples that exceed the preset discrete range from the multiple amplitude ratio samples, and determining the average value of the remaining amplitude ratio samples as the coupling coefficient.

[0017] Therefore, when determining the coupling coefficient, collecting the peak velocity and extreme values ​​of attenuation duration over multiple time periods, removing samples that exceed the discrete range, and taking the average value as the coupling coefficient can eliminate the influence of accidental interference and spurious correlation events, making the coupling coefficient more robust and representative, and ensuring the stability and long-term effectiveness of velocity compensation.

[0018] In conjunction with the first aspect, optionally, based on the coupling coefficient, the fluctuation of the real-time travel speed is converted into an attenuation duration compensation amount, including: obtaining the speed deviation of the real-time travel speed relative to the reference speed; multiplying the speed deviation by the coupling coefficient to obtain the initial compensation amount; obtaining the transmission delay time between the spunlace nonwoven fabric passing through the measurement point and reaching the rewinding roller; and time-aligning the initial compensation amount based on the transmission delay time to generate the attenuation duration compensation amount.

[0019] Therefore, after multiplying the speed deviation by the coupling coefficient to obtain the initial compensation amount, the initial compensation amount is time-aligned based on the transmission delay time between the measurement point and the rewinding roll to generate the attenuation duration compensation amount. This ensures that the compensation timing matches the timing of the interference, avoids residual errors caused by compensation being ahead or behind, and improves the compensation accuracy.

[0020] In conjunction with the first aspect, optionally, the method further includes: acquiring at least one determined historical attenuation duration within the time interval between two consecutive determinations of attenuation duration; comparing the historical attenuation duration with a preset ideal attenuation duration interval, wherein the lower limit of the ideal attenuation duration interval corresponds to the lower limit of the response sensitivity of the electrostatic sensor, and the upper limit corresponds to the upper limit of the response saturation of the electrostatic sensor; when the historical attenuation duration is lower than the lower limit of the ideal attenuation duration interval, increasing the preset charge value by a preset increment; when the historical attenuation duration is higher than the upper limit of the ideal attenuation duration interval, decreasing the preset charge value by a preset increment, wherein the preset charge value is the charge threshold used to determine the start and end of the attenuation duration in the attenuation data, and increasing or decreasing the preset charge value makes the measurement window of the attenuation duration expand or contract within the ideal attenuation duration interval.

[0021] Therefore, by monitoring historical decay times and comparing them with the ideal decay time range, the preset charge value can be dynamically adjusted to ensure that the decay time is always within the range where the sensor has high response sensitivity and good linearity. This avoids problems such as sensor signal saturation or insufficient signal-to-noise ratio, and improves the measurement system's adaptability to environmental changes and batch differences, as well as the long-term stability of tension measurement.

[0022] Secondly, this application proposes an intelligent rewinding control system for spunlace nonwoven fabric, including an electrostatic sensor, a rewinding roller, a high-voltage power supply disposed on the rewinding roller, and a control terminal. The system includes:

[0023] The first determining module is used to determine the real-time tension of the spunlace nonwoven fabric based on the decay time of the charge carried by the spunlace nonwoven fabric during the rewinding process, including:

[0024] The first acquisition module is used to acquire data on the attenuation of charge on the spunlace nonwoven fabric over time as it passes through the measurement point, based on an electrostatic sensor.

[0025] The second determining module is used to determine the time taken for the charge to decay from the initial monitoring value to the preset charge value from the decay data as the decay duration.

[0026] The comparison module is used to compare the attenuation time with a preset first mapping data table to determine the real-time tension corresponding to the attenuation time.

[0027] The third acquisition module is used to determine the electrostatic field strength applied to the surface of the rewinding roll based on the real-time tension.

[0028] The control module is used to control the output voltage of the high-voltage power supply based on the electrostatic field strength.

[0029] A third aspect of the present invention provides a processing apparatus, the processing apparatus comprising:

[0030] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method proposed in the first aspect of the present invention.

[0031] A fourth aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the method as described in the first aspect of the present invention. Attached Figure Description

[0032] Figure 1 This is a flowchart illustrating an intelligent rewinding control method for spunlace nonwoven fabric proposed in an embodiment of this application.

[0033] Figure 2 This is a flowchart illustrating the first mapping data establishment method in a smart rewinding control method for spunlace nonwoven fabric proposed in an embodiment of this application.

[0034] Figure 3 This is a flowchart illustrating the second mapping data establishment method in a smart rewinding control method for spunlace nonwoven fabric proposed in an embodiment of this application.

[0035] Figure 4 This is a schematic diagram of the structure of an intelligent rewinding control system for spunlace nonwoven fabric proposed in an embodiment of this application.

[0036] Figure 5 This is a schematic diagram of the structure of a processing device proposed in an embodiment of this application. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] This application proposes an intelligent rewinding control system for spunlace nonwoven fabrics, including:

[0039] An electrostatic sensor, installed at measurement point P on the rewinding path, is used to non-contactly sense the amount of charge carried by the passing spunlace nonwoven fabric and outputs data on the decay of the charge over time. The electrostatic sensor can be an electrometer, an electric field induction probe, etc. For example, a contact electrometer (such as the KeyenceSK series) or a non-contact electric field induction probe (such as the Trek5200 series) can be used. Its installation location is typically chosen in a section where the charge distribution on the fabric surface is uniform and mechanical vibration is minimal, such as 0.5 to 1 meter after the drying station and before the rewinding roller.

[0040] Rewinding rollers are used to wind spunlace nonwoven fabrics. Their surface is made of conductive material or covered with a conductive layer and is electrically connected to the output of a high-voltage power supply. The conductive material can be stainless steel or aluminum alloy, and the surface can be electroplated with chromium to increase wear resistance; a conductive rubber coating can also be used to increase friction and prevent slippage.

[0041] A high-voltage power supply can output an adjustable high voltage to charge the surface of the rewinding roller, thereby creating an electrostatic field between the roller surface and the ground or surrounding guides. This field applies a radial electrostatic adsorption force to the wound spunlace nonwoven fabric, which can be equivalent to an additional tension along the fabric surface. The output voltage range of the high-voltage power supply is typically 0~10kV, and it can be positive or negative. The output polarity is selected according to the polarity of the charge on the spunlace fabric to enhance the adsorption effect, and its response time is better than 1ms.

[0042] Control terminals, such as industrial computers, PLC programmable logic controllers, or embedded controllers, are connected to electrostatic sensors, high-voltage power supplies, and speed measuring devices, such as encoders, via signal lines to obtain real-time travel speed and control actuators such as rewinding motors through drive interfaces.

[0043] The control terminal includes a memory, a processor, and software modules stored in the memory for executing the method steps described below. The control terminal is preferably an embedded system based on an ARM Cortex-M series or FPGA, running a real-time operating system (such as FreeRTOS) to ensure real-time data acquisition and control.

[0044] This application proposes an intelligent rewinding control method for spunlace nonwoven fabrics. Please refer to [link / reference]. Figure 1 This includes the following steps: S101~S103:

[0045] S101: Determine the real-time tension of the spunlace nonwoven fabric based on the decay time of the charge carried by the spunlace nonwoven fabric during the rewinding process.

[0046] Understandably, during the production of spunlace nonwoven fabrics, a certain amount of static charge accumulates on the fiber surface due to the impact of high-pressure water jets and friction between fibers. During the rewinding process, this charge gradually dissipates as the fabric moves and comes into contact with air and guide rollers. The rate of dissipation depends not only on environmental conditions but also on the internal stress state of the nonwoven fabric, i.e., tension. When the nonwoven fabric is under high tension, the fibers are stretched, altering the surface microstructure and charge trap distribution, causing the charge dissipation rate to increase or decrease. Utilizing this physical phenomenon, the current tension value can be inferred by measuring the duration of the charge decay process, thus achieving non-contact tension sensing.

[0047] Specifically, step S101 may include the following steps S1011 to S1013:

[0048] S1011: Based on an electrostatic sensor, data on the attenuation of charge on spunlace nonwoven fabric over time as it passes through a measurement point are obtained.

[0049] For example, an electrostatic sensor is installed at a selected location on the rewinding path, i.e., a measurement point. The sensor can be an electrometer, an electric field induction probe, or a non-contact electrostatic voltmeter, etc.

[0050] As the spunlace nonwoven fabric continuously passes through the measurement points, the sensor continuously collects the amount of charge or a proportional potential signal on the fabric surface at a fixed sampling frequency, forming a curve showing the change of charge over time. The curve generally exhibits a pattern of first rising and then decaying: when the charged fabric enters the sensor's sensitive area, the signal amplitude rises rapidly; as the fabric continues to move, the charge gradually decays, and the signal decreases accordingly. This complete signal sequence output by the sensor is the decay data, recording the charge value at each sampling moment. The sampling frequency is generally not lower than 1kHz to ensure accurate capture of the details of the decay process, and a sensor analog bandwidth greater than 10kHz is recommended.

[0051] S1012: Determine the time taken for the charge to decay from the initial monitoring value to the preset charge value from the decay data as the decay duration.

[0052] Understandably, a starting reference point, or initial monitoring value, can be defined from the collected attenuation data. The initial monitoring value can be the maximum value of the signal after entering the steady-state induction region, or a fixed percentage of that maximum value, such as 90% of the peak voltage, to ensure good consistency and noise immunity at the starting point. Alternatively, 85% or 95% of the peak voltage can be chosen as a compromise, with the specific percentage optimized based on the signal-to-noise ratio. Simultaneously, a preset charge value is pre-set as the threshold for determining the end of attenuation. The preset charge value is usually selected in a segment of the signal attenuation curve with good linearity, ensuring sufficient measurement time without frequent false triggers due to noise interference. The initial value of the preset charge is generally selected as 10% to 20% of the initial monitoring value. This value should be located in the linear segment of the attenuation curve and can be determined by observing the attenuation curve with an oscilloscope during debugging. Timing begins from the instant the signal amplitude first drops below the initial monitoring value until the signal amplitude attenuates to the preset charge value; this time period is the attenuation duration. This duration can be accurately measured using circuitry or digital signal processing methods, such as comparator-triggered timing with a counter.

[0053] S1013: Compare the attenuation time with the preset first mapping data table to determine the real-time tension corresponding to the attenuation time.

[0054] Understandably, a pre-established first mapping data table stores the correspondence between decay time and tension. This table can be obtained through offline experiments, such as repeatedly measuring the decay time of spunlace nonwoven fabric under different known tension conditions, recording and organizing the data. During real-time control, the decay time is used as input and searched in the first mapping data table. If the measured decay time falls between two known values ​​in the table, the corresponding real-time tension value can be calculated using linear interpolation or curve fitting. Piecewise linear interpolation is recommended to balance accuracy and computational complexity; for applications requiring extremely high smoothness, cubic spline interpolation or exponential fitting based on a physical model can be used instead. The table lookup process essentially completes the inverse transformation of sensor calibration from charge decay characteristics to tension, converting non-contact electrostatic measurement into a tension signal that can be directly used for control.

[0055] For example, please refer to Figure 2 The first mapping data can be established using the following steps S201~S204:

[0056] S201: Cut the spunlace nonwoven fabric of the same batch into calibration sample fabrics and fix the calibration sample fabrics in a calibration device, wherein the calibration device includes an application electrode plate and a ground electrode plate arranged in parallel, and the calibration sample fabrics are located between the application electrode plate and the ground electrode plate.

[0057] Understandably, to ensure that the initial mapping data sheet has consistent charge decay characteristics with the spunlace nonwoven fabric in actual production, a piece of appropriately sized fabric needs to be cut from the same roll or batch of nonwoven fabric in the current production run as a calibration sample. The recommended size for the calibration sample is 100mm × 200mm, with the fiber direction aligned with the length direction. Ceramic scissors or laser cutting should be used to avoid introducing additional charge. This calibration sample is then fixed in a specially designed calibration device. This device contains two parallel metal plates: one is an application electrode plate, used to connect to a high-voltage power supply and generate an electric field; the other is a grounding electrode plate, reliably grounded. The calibration sample is placed in the space between the two electrode plates, typically held at both ends by insulating clamps to keep the fabric surface flat and prevent direct contact with the electrode plates, thus avoiding charge leakage. This arrangement ensures a uniform electric field is formed between the two plates, within which the calibration sample experiences an electrostatic force perpendicular to the fabric surface. The electrode plate spacing is usually set to 5~10mm, and the area of ​​the applied electrode plate should be larger than the area of ​​the sample cloth to ensure a uniform electric field.

[0058] S202: Output multiple calibration voltages of known amplitude to the applied electrode plate, so that the calibration sample cloth is subjected to multiple corresponding known electrostatic forces, wherein each known electrostatic force is equivalent to a known calibration tension.

[0059] During calibration, the control terminal sequentially outputs a series of pre-set calibration voltage values, such as 500V, 1000V, and 1500V, to the application electrode plates. Depending on the voltage, different intensities of electrostatic fields are generated between the two plates. This electric field exerts a force on the bound or polarized charges within the calibration sample fabric, i.e., an electrostatic force. Since the electric field direction on both sides of the fabric surface is perpendicular to the fabric surface, this normal force causes the fabric surface to slightly elongate or be under stress, effectively equivalent to applying a tensile tension in the in-plane direction of the fabric surface. For each calibration voltage, the magnitude of the equivalent tensile tension can be obtained through pre-calibration or theoretical calculation, for example, by directly measuring the constraint reaction force of the fabric surface using a high-precision force sensor, or by converting it from the known elastic modulus of the fabric surface and the relationship between the electric field force and elongation. During calibration, it is recommended to use a high-precision tensile sensor (such as the HBMS2M series) to directly measure the constraint reaction force at both ends of the sample fabric, with an accuracy of up to 0.01N. Alternatively, it can be estimated using the electrostatic force formula, where parameters such as vacuum dielectric constant, fabric relative dielectric constant, electrode area, electric field strength, and spacing need to be determined in advance. In this way, each calibration voltage corresponds one-to-one with a known calibration tension.

[0060] S203: The time it takes for the charge amount of the calibration sample cloth corresponding to each known calibration tension to decay from the initial monitoring value to the preset charge value is obtained and determined as the calibration decay time.

[0061] While applying a calibration voltage to maintain a known calibration tension, the charge decay process on the calibration sample is measured using an electrostatic sensor identical to that used in online measurements.

[0062] For example, similar to S1011 and S1012, the calibration sample fabric can be charged with a certain amount of initial charge through contact or non-contact charging, and then charging can be stopped to allow the charge to decay naturally. For non-contact charging, a corona discharge needle can be swept over the sample fabric, with a charging voltage of 2-5 kV and a charging time of 1-2 seconds to ensure sufficient and uniform initial charge distribution. The electrostatic sensor records the time it takes for the charge to decrease from the initial monitored value to the preset charge value. This time is the calibration decay time under the known calibration tension. For each set calibration tension value, the above measurement is repeated, and the corresponding calibration decay time is recorded.

[0063] S204: Pair the known calibration tension with the corresponding calibration decay time to form the first mapping data table.

[0064] Each known calibrated tension value is paired with its corresponding measured calibrated attenuation time value to form multiple "tension and attenuation time" data pairs. These data pairs are arranged in ascending order of attenuation time and stored in the control terminal's memory in the form of a data table, thus forming the first mapping data table.

[0065] Since the calibration sample fabric and the online rewinding spunlace nonwoven fabric belong to the same batch, their material composition, fiber structure, surface resistivity and other characteristics are highly consistent. Therefore, the correspondence between "attenuation time and tension" stored in this table can accurately reflect the physical relationship between the two in the actual rewinding process.

[0066] S102: Determine the electrostatic field strength applied to the surface of the rewinding roll based on real-time tension.

[0067] Understandably, after obtaining the real-time tension value, the control terminal needs to decide how to apply an electrostatic field to the surface of the rewinding roll in order to adjust the actual tension to the desired level.

[0068] Specifically, the required electrostatic field strength amplitude can be determined based on the relationship between the real-time tension and the target tension. For example, a feedback control algorithm can be used: when the real-time tension is lower than the target tension, the electrostatic field strength needs to be increased by applying a greater electrostatic adsorption force to the nonwoven fabric through the rewinding roller, which is equivalent to an additional tension along the fabric surface; when the real-time tension is higher than the target tension, the electrostatic field strength is decreased. The controller calculates the electrostatic field strength command value according to a predetermined control law, such as proportional control or proportional-integral control, based on the difference between the real-time tension and the target tension. Alternatively, the required field strength can be directly obtained from the real-time tension using a preset tension-electrostatic field strength function curve or by looking up a table. The specific implementation method depends on the system characteristics and does not deviate from the essence of this step.

[0069] Specifically, step S102 may include the following steps: S1021~S1022:

[0070] S1021: Compare the real-time tension with the target tension to obtain the deviation.

[0071] Understandably, in step S101, the control terminal has already obtained the actual tension value of the spunlace nonwoven fabric at the current moment, i.e., the real-time tension, by comparing the charge decay time with the first mapping data table. The real-time tension reflects the actual stress state of the fabric surface at the measurement point during the rewinding process. The target tension is a desired tension value preset according to the production process requirements, such as a constant value or a curve value that changes according to a certain pattern, determined based on the nonwoven fabric's basis weight, width, roll diameter, and subsequent processing requirements. The comparison process usually uses subtraction, for example, subtracting the target tension value from the real-time tension value, and the result is the deviation.

[0072] The sign of the deviation indicates the direction of tension deviation. A positive value indicates that the real-time tension is too high, and the nonwoven fabric is overstretched; a negative value indicates that the real-time tension is too low, and the winding may be too loose. The absolute value of the deviation represents the magnitude of the difference between the current tension and the target value.

[0073] S1022: Find the corresponding electrostatic field strength from the preset second mapping data table according to the deviation.

[0074] The second mapping data table is a pre-stored correspondence table in the control terminal. This table establishes the mapping relationship between the tension deviation and the required electrostatic field strength. Its construction can be completed based on theoretical calculations, offline experiments, or online identification, but at the time of execution of this step, the table already exists and can be called.

[0075] For example, please refer to Figure 3 The second mapping data is established in the following way:

[0076] S301: When the spunlace nonwoven fabric is rewound at a constant speed and under the target tension, control the output test voltage of the high voltage power supply to generate a test electrostatic field with a step increase on the surface of the rewinding roller.

[0077] During normal operation of the rewinding equipment, once the control system has adjusted and stabilized the real-time tension of the spunlace nonwoven fabric near the preset target tension value, and the fabric travel speed remains constant, the control terminal actively sends a test command to the high-voltage power supply. The command requires the high-voltage power supply to suddenly increase its output voltage from a reference value, such as zero or the current operating voltage, to a predetermined test value within a very short time, and maintain this test value for a period of time. This rapid jump in output voltage generates a suddenly increasing, step-like electrostatic field on the surface of the rewinding roller, called the test electrostatic field. This step disturbance provides the system with an excitation signal of known amplitude for probing the tension response characteristics of the rewinding process under this condition. The reference voltage is usually selected as the current normal operating voltage or 0V, the step amplitude can be selected from 10% to 30% of the operating voltage range, such as 500V, 800V, 1200V, etc., and the holding time should be at least twice the system stabilization time, generally set to 200~500ms.

[0078] S302: During the test of the electrostatic field, the change in charge decay time of the spunlace nonwoven fabric is obtained, and the change in charge decay time is converted into a tension response curve based on the first mapping data table.

[0079] Throughout the entire period of the applied electrostatic field test, the electrostatic sensor continuously collects charge decay data of the spunlace nonwoven fabric at the measurement point and continuously calculates the current decay time according to step S1012. Understandably, because the presence of the test electrostatic field changes the additional tension borne by the fabric surface, the charge decay characteristics of the fabric surface will change accordingly, and thus the decay time will fluctuate accordingly. The control terminal records this series of decay time values ​​that change over time, and then, for each decay time value, uses the established and used first mapping data table to convert the decay time value into the corresponding real-time tension value through table lookup or interpolation. Arranging the converted tension values ​​in chronological order forms a curve that reflects the dynamic changes in tension, namely the tension response curve. This curve describes the complete process of the tension of the spunlace nonwoven fabric after being excited by a step electric field, starting from the original steady state, undergoing a dynamic transition, and eventually approaching a new steady state.

[0080] S303: Identify the tension peak and settling time from the tension response curve, and determine the mapping relationship between the electrostatic field strength and the tension deviation based on the offset of the tension peak relative to the target tension and the step amplitude of the test electrostatic field strength.

[0081] Specifically, on the tension response curve, the control terminal can perform feature extraction using signal processing techniques. First, the maximum amplitude of tension reached on the curve is identified as the tension peak value. This peak value usually appears shortly after the electric field step is applied, reflecting the system's maximum response to the excitation.

[0082] Simultaneously, the time from the moment the step change is applied until the tension response enters and remains within a certain stable range is recorded; this is the settling time. The stable range can be defined as the tension value variation not exceeding ±2% of the final steady-state value, and this threshold can be configured according to the noise level. Next, the difference between the peak tension and the target tension before the test is calculated; this difference is the tension offset. Correspondingly, the step amplitude of the test electrostatic field strength is a known quantity determined based on the known amplitude of the test voltage and the structural parameters of the rewinding roll. This set of "test electrostatic field strength step amplitude" and "tension offset" can be considered as a mapping point; the quantitative relationship between them directly constitutes the mapping relationship between the electrostatic field strength and the tension deviation at this operating point. For example, if the test electrostatic field strength step amplitude is E, and the corresponding tension offset is ΔF, then for a deviation of ΔF, an electrostatic field of strength E needs to be applied for compensation.

[0083] S304: Based on multiple different step amplitude values ​​of the test voltage, obtain multiple sets of data to generate a second mapping data table.

[0084] Understandably, to fully cover various tension deviations that may occur during the actual rewinding process and to completely characterize the correspondence between electrostatic field strength and tension deviation, the control terminal selects multiple test voltages of different amplitudes and repeatedly executes steps S301 to S303. Each test yields a set of corresponding "test electrostatic field strength step amplitude and tension deviation" data. These data from different step amplitudes are summarized, sorted, and possibly smoothed or curve-fitted to form a systematic correspondence table, i.e., the second mapping data table. Smoothing can be performed using moving average, Savitzky-Golay filtering, or penalized least squares fitting to ensure that the mapping curve is monotonic and smooth. The second mapping data table stores the mapping values ​​between the two under different operating conditions, using tension deviation as an index or electrostatic field strength as an index. In subsequent real-time control, when a certain tension deviation is calculated, the required electrostatic field strength value can be directly retrieved from this table, thus completing the rapid conversion from tension deviation to control output.

[0085] Once the deviation is calculated, the control terminal uses this deviation as input to search the second mapping data table. If the deviation corresponds exactly to a discrete point in the table, the electrostatic field strength value corresponding to that point is directly retrieved; if the deviation falls between two discrete points, the corresponding electrostatic field strength value is calculated through linear interpolation or other interpolation methods. The electrostatic field strength value obtained from the table is the target electric field strength value that should be applied to the surface of the rewinding roller. Subsequent steps will use this value to control the output voltage of the high-voltage power supply to generate a corresponding electrostatic field, thereby adjusting the fabric tension through electric field force to bring it closer to the target tension.

[0086] S103: Controls the output voltage of a high-voltage power supply based on electrostatic field strength.

[0087] Understandably, as an electrode for applying an electrostatic field, the surface electric field strength of the rewinding roll has a definite physical relationship with the output voltage of the high-voltage power supply applied to it. This relationship depends on the geometry and size of the rewinding roll, the distance between the roll surface and surrounding grounded bodies such as the frame and guide rolls, and the distribution of the medium.

[0088] Generally speaking, electric field strength is directly proportional to voltage and inversely proportional to distance. The control terminal converts the electrostatic field strength value, combined with a preset voltage and field strength conversion factor, into the required high voltage output value, and then sends the output adjustment command to the high voltage power supply via digital-to-analog conversion or communication interface.

[0089] The high-voltage power supply adjusts its output voltage accordingly, thereby creating an electrostatic field of corresponding strength on the surface of the rewinding roller. The Maxwell stress generated by this electric field acts on the spunlace nonwoven fabric winding around the roller surface, effectively adding an additional tension component to the fabric surface, causing the actual tension to approach the target value, thus completing closed-loop regulation. The entire process requires no mechanical actuators, has a high response speed, and completely avoids physical contact with the fabric surface.

[0090] Alternatively, in some other embodiments, determining the real-time tension may further include the following steps:

[0091] S401: Obtain the real-time travel speed of the spunlace nonwoven fabric at the measurement point.

[0092] Understandably, during the rewinding process, the spunlace nonwoven fabric is dragged by the traction mechanism, passing through the measurement point at a certain linear speed. To capture the real-time changes in the fabric's travel speed, the system sets up speed detection devices near the measurement point or along the transmission path, such as speed measuring rollers and their encoders in contact with the fabric surface, or non-contact laser Doppler speed sensors. As an alternative, when contact with the fabric surface is not permitted, non-contact laser Doppler sensors (such as the Polytec LSV series) can be used to avoid measurement errors caused by contact damage or slippage. The device continuously measures and outputs a signal representing the actual movement speed of the fabric surface. The control terminal acquires this signal at fixed intervals, thereby obtaining real-time travel speed data, which reflects the speed of the fabric surface movement and its slight fluctuations over time.

[0093] S402: Based on the real-time travel speed, determine the speed fluctuation sequence and obtain the speed peak value and the corresponding first timestamp in the speed fluctuation sequence.

[0094] Understandably, the real-time travel speed should ideally be a constant value. However, due to factors such as motor torque pulsation, guide roller eccentricity, and friction variations, the actual speed always fluctuates around a baseline value. Subtracting the baseline speed, such as the average speed over a period of time or the set speed, from continuously collected real-time travel speed data yields a speed deviation sequence, i.e., a speed fluctuation sequence. The baseline speed can be the setpoint of the incoming line speed or a moving average of measurements taken within the last 10 seconds to track slow drift. Then, extreme value detection is performed on this fluctuation sequence: the local maximum value point where the fluctuation changes from rising to falling is identified, its amplitude is recorded as the speed peak, and the sampling time of this peak is taken as the first timestamp. Peak detection can be achieved by comparing three adjacent points; the middle point being higher than the two sides indicates a peak value. A minimum peak height threshold (e.g., 0.5% of the baseline speed) is set to ignore spurious peaks caused by minor noise. This yields multiple "speed peak and first timestamp" data pairs, used to characterize the intensity and timing of speed disturbances.

[0095] S403: Based on the decay duration, determine the decay duration fluctuation sequence, and obtain the decay duration extreme value and the corresponding second timestamp in the decay duration fluctuation sequence.

[0096] In parallel with step S402, the control terminal analyzes the continuously calculated decay duration. The decay duration also fluctuates due to tension changes and velocity disturbances. From the continuous observations of the decay duration, a decay duration fluctuation sequence is obtained through a similar mean-reduction process. Then, local extrema are sought in this sequence; since the decay duration may shorten with increasing velocity or lengthen with decreasing velocity, the extrema (maximum or minimum value) correspond to the maximum impact caused by velocity fluctuations. Extremum detection considers both maximum and minimum values ​​as candidate extrema, and can be further filtered based on subsequent correlations. The amplitudes of these extrema are recorded as decay duration extrema, and their occurrence times are recorded as the second timestamp. This yields several pairs of "decay duration extrema and second timestamp" data.

[0097] S404: Compare the first timestamp and the second timestamp within the same time period to determine the time difference.

[0098] During a continuous rewinding operation, the first timestamp of the speed fluctuation obtained in step S402 is compared with the second timestamp of the decay duration fluctuation obtained in step S403 on the same time axis. For each extreme decay duration event, the speed peak event that is closest to it in time is found, and the absolute value of the difference between the two timestamps is calculated, i.e., the time difference. If the speed fluctuation is the cause of the decay duration fluctuation, then the two types of events should closely follow each other in time, rather than being randomly distributed or far apart. To eliminate the influence of the fixed transmission delay, an estimated value can be subtracted from the second timestamp before comparison. This estimated value is equal to the transmission delay time from the measurement point to the rewinding roll.

[0099] S405: When the absolute value of the time difference is less than the preset time correlation threshold, the fluctuation of the decay duration is determined to be caused by the fluctuation of the real-time travel speed.

[0100] Specifically, the calculated time difference is compared with a preset time correlation threshold. The correlation threshold is determined based on the system's dynamic response characteristics and sampling interval; for example, it can be set to several sampling periods. Generally, the correlation threshold is set to 2-5 times the sampling period; for example, when the sampling period is 10ms, the threshold can be set to 20-50ms. If the time difference between a pair of peaks is less than this threshold, it is considered that this set of velocity peaks and the extreme values ​​of decay duration are causally correlated in time. That is, the fluctuation in decay duration is not caused by a real change in tension, but by an instantaneous change in travel speed. In this way, the source of interference is identified through time proximity.

[0101] S406: Determine the coupling coefficient based on the amplitude ratio between the peak velocity and the extreme value of the decay time.

[0102] For each pair of velocity peaks and decay duration extremes identified as correlated, the amplitude ratio between the two is calculated, which is the fluctuation amplitude of the decay duration extreme divided by the fluctuation amplitude of the velocity peak. This ratio represents the change in decay duration caused by a unit velocity fluctuation, equivalent to the sensitivity of velocity to decay duration measurement interference. Multiple sets of correlated events can be continuously collected to obtain multiple amplitude ratio samples. To ensure the representativeness of the coefficients, these samples can be statistically analyzed to obtain a comprehensive coupling coefficient, which is used to quantitatively characterize the relationship between velocity fluctuations and decay duration fluctuations.

[0103] For example, step S406 may include the following steps S4061 to S4063:

[0104] S4061: Obtain the peak speed and the corresponding extreme values ​​of decay time within multiple different time periods.

[0105] In step S405, several pairs of events caused by speed fluctuations and decay duration fluctuations have been identified through time difference comparison. Each pair contains a speed peak and its associated decay duration extreme value. However, since a single or a few events may be affected by random noise, accidental disturbances, or local operating condition changes, the coupling relationship reflected is not stable or reliable. Therefore, this step intentionally expands the time span of data acquisition, executing steps S402 to S405 at multiple different time periods during the rewinding process, such as the start-up phase, the constant speed phase, and different roll diameter periods, to cover various operating conditions such as changes in tension setpoint, speed, and winding roll diameter, thereby improving the generalization ability of the coupling coefficient and obtaining multiple sets of effective event pairs scattered under different operating conditions. Each event pair records the speed peak value and its causally associated decay duration extreme value, forming a sample pair.

[0106] S4062: Obtain the amplitude ratio of each pair of peak velocity and extreme decay time values ​​to obtain multiple amplitude ratio samples.

[0107] For each valid pair of velocity peaks and attenuation duration extrema, the amplitude ratio between them is calculated. The amplitude ratio is specifically calculated by dividing the deviation of the attenuation duration extrema relative to the attenuation duration reference value by the deviation of the velocity peak relative to the velocity reference value. The attenuation duration reference value can be obtained by low-pass filtering the attenuation duration sequence within this period (e.g., a Butterworth filter with a cutoff frequency of 0.1 Hz), representing a slowly changing baseline level. The ratio represents the change in attenuation duration caused by a unit velocity fluctuation, i.e., the interference gain of velocity on the attenuation duration measurement channel. Since there are multiple event pairs, calculating each pair yields a series of amplitude ratio samples, which form a sample set used to statistically analyze the central tendency of this coupling relationship.

[0108] S4063: Remove samples that exceed the preset discrete range from multiple amplitude ratio samples, and determine the average value of the remaining amplitude ratio samples as the coupling coefficient.

[0109] Among multiple amplitude ratio samples, there may be spurious event pairs caused by accidental overlap of velocity fluctuations and decay duration fluctuations rather than a true causal relationship, or abnormal amplitudes caused by instantaneous sensor interference. In order to obtain coupling coefficients that can reflect the true physical relationship, these samples need to be screened for reliability.

[0110] A pre-defined discrete range is established, such as an interval centered at the sample mean and with a radius equal to a certain number of standard deviations. For example, the 3σ criterion is used, retaining data within the range of the sample mean ± 3 standard deviations, with a rejection rate typically not exceeding 5%. Each amplitude ratio sample is examined one by one; if its value falls outside the pre-defined discrete range, it is considered an outlier and is rejected, not participating in subsequent calculations. The retained sample set after screening exhibits good data consistency, and its arithmetic mean is the final determined coupling coefficient. The average value integrates information from multiple runtime phases, smooths out random errors, and stably represents the quantitative coupling relationship between velocity fluctuations and decay duration fluctuations, which is used in step S407 to convert real-time velocity fluctuations into decay duration compensation values.

[0111] S407: Based on the coupling coefficient, the fluctuation of real-time travel speed is converted into the decay time compensation amount.

[0112] In actual real-time tension calculation, the control terminal continuously monitors the real-time travel speed and calculates its deviation from the reference speed, i.e., the speed fluctuation. Using a defined coupling coefficient, the speed fluctuation is multiplied by the coupling coefficient to obtain an initial attenuation time compensation. This initial compensation represents the spurious increase or decrease in attenuation time caused by speed disturbance under the current speed fluctuation.

[0113] Specifically, step S407 may include the following steps: S4071~S4074:

[0114] S4071: Obtain the speed deviation of the real-time travel speed relative to the reference speed.

[0115] In step S401, the system continuously collects the real-time travel speed of the spunlace nonwoven fabric at the measurement point. The reference speed is the desired constant speed set by the rewinding process, or it can be automatically determined by the control system based on the statistical average of real-time travel speeds over a relatively long period. The reference speed can be selected as the process-set speed or the sliding average of the real-time speed to simultaneously consider steady-state and gradually changing conditions. The speed deviation is obtained by algebraically subtracting the real-time travel speed collected at the current moment from this reference speed. The speed deviation has a positive and negative sign: when the real-time travel speed is higher than the reference speed, the deviation is positive, indicating that the fabric is moving too fast; when the real-time travel speed is lower than the reference speed, the deviation is negative, indicating that the fabric is moving too slowly. This speed deviation reflects the magnitude and direction of the current instantaneous speed fluctuation.

[0116] S4072: Multiply the speed deviation by the coupling coefficient to obtain the initial compensation amount.

[0117] Specifically, the velocity deviation value is directly multiplied by the coupling coefficient, and the product is the initial compensation amount. Since the velocity deviation can be positive or negative, the initial compensation amount also has a corresponding sign: when the velocity is too high, resulting in an abnormally short decay time, the initial compensation amount is negative; when the velocity is too low, resulting in an abnormally long decay time, the initial compensation amount is positive. This multiplication linearly converts the fluctuation in the velocity domain into an estimate of the decay time fluctuation in the time domain.

[0118] S4073: Obtain the transfer delay time between the spunlace nonwoven fabric passing through the measurement point and reaching the rewinding roller.

[0119] Understandably, the spunlace nonwoven fabric moves continuously from the measuring point to the rewinding roller along the rewinding path, passing several guide rollers along the way. The actual length of this path is a known equipment parameter. Dividing it by the average travel speed of the fabric surface during the rewinding process yields the transmission delay time. This delay time can be measured during equipment commissioning by marking the fabric surface (e.g., attaching reflective sheets) and recording the time difference between the measuring point and the sensor near the rewinding roller; a typical value is between 0.5 and 2 seconds. Alternatively, it can be automatically identified during operation through correlation analysis, i.e., finding the maximum cross-correlation delay between speed fluctuations and tension response. The transmission delay time can also be measured by setting marks on the fabric surface and recording the time difference between the measuring point and the rewinding roller. This delay time describes the time taken for a point on the fabric surface to travel from the measuring point to the rewinding roller, and is a key timing parameter connecting the measuring end and the control execution end.

[0120] S4074: Time-align the initial compensation amount based on the transmission delay time to generate the attenuation duration compensation amount.

[0121] Understandably, the initial compensation amount obtained in step S4072 is calculated based on the real-time velocity deviation at the current measurement point, but the attenuation duration to be compensated is determined from the charge attenuation data, and there is a certain time window between the acquisition of attenuation data and the calculation of attenuation duration.

[0122] Meanwhile, the effect of velocity fluctuations on the charge decay characteristics of the fabric surface is not entirely instantaneous; local stress changes on the fabric surface may also require a small propagation time. To ensure that the compensation action accurately corresponds to the interference effect in timing, the initial compensation amount is time-aligned using the acquired propagation delay time. Time alignment can be achieved through a digital delay line: the initial compensation amount is sequentially stored in a FIFO (First-In-First-Out) queue buffer, with the queue depth equal to the delay time divided by the sampling period, and then read out according to the beat as the final compensation amount.

[0123] Specifically, the initial compensation amount can be shifted forward or backward on the time axis by an amount related to the transmission delay time, or the currently calculated initial compensation amount can be matched with the velocity deviation event at a previous moment to generate a final compensation value that matches the current attenuation duration to be corrected in time, i.e., the attenuation duration compensation amount. After time alignment, this attenuation duration compensation amount can accurately offset the spurious changes in the current attenuation duration introduced by velocity fluctuations.

[0124] S408: Subtract the attenuation compensation amount from the current attenuation duration to obtain the compensated attenuation duration.

[0125] The directly measured current decay time is algebraically subtracted from the calculated decay time compensation. If the compensation is positive, it indicates that the decay time is too large due to velocity fluctuations, so the decay time decreases after subtracting the compensation; conversely, if the compensation is negative, the decay time decreases. Through this subtraction, the interference component introduced by velocity fluctuations is removed from the measured decay time, yielding the compensated decay time, which more purely reflects the change in charge decay time caused by actual tension changes.

[0126] S409: Determine the real-time tension based on the compensated attenuation time and the first mapping data table.

[0127] Finally, using the same lookup method as in step S1013, the compensated attenuation time obtained in step S408 is used as input to perform lookup and interpolation in the pre-established first mapping data table to obtain the corresponding real-time tension. Since the attenuation time here has eliminated the interference of speed fluctuations, the real-time tension determined in this way is more accurate, providing a basis for the controlled variable for further determination of electrostatic field strength and tension closed-loop control.

[0128] Optionally, to ensure that the electrostatic sensor remains in a state of high sensitivity and high linearity for a long period of time, and to improve the accuracy and anti-interference capability of real-time tension measurement, the method may further include the following steps: S501~S504:

[0129] S501: Within the time interval between two consecutive determinations of attenuation duration, obtain at least one determined historical attenuation duration.

[0130] Understandably, during the rewinding control process, the control terminal does not immediately perform measurement window calibration after each attenuation duration calculation. Instead, it retrieves the results of several completed attenuation duration calculations during idle periods between two attenuation duration determinations, or during relatively stable system operation intervals. These results are recent valid measurement data stored in memory, reflecting the actual rate of charge decay in the previous stage. The historical attenuation duration obtained here can be a single value from the most recent measurement, an average of multiple measurements, or a representative value within a sliding window. For example, the arithmetic mean of the most recent 5-10 valid measurements, or an exponentially weighted average to highlight recent trends, can be used. The purpose is to serve as a basis for evaluating whether the current preset charge value setting is appropriate.

[0131] S502: Compare the historical decay time with the preset ideal decay time range, where the lower limit of the ideal decay time range corresponds to the lower limit of the response sensitivity of the electrostatic sensor, and the upper limit corresponds to the upper limit of the response saturation of the electrostatic sensor.

[0132] Specifically, the system pre-stores an ideal attenuation time range, the two endpoints of which are pre-calibrated based on the characteristics of the electrostatic sensor used. Specifically, the lower limit represents the minimum attenuation time the sensor can reliably resolve: if the measured attenuation time is shorter than the lower limit, it means the charge attenuation rate is too fast, the sensor's output signal amplitude changes very little, and it is easily drowned out by measurement noise, resulting in insufficient signal-to-noise ratio and a significant decrease in sensitivity. The upper limit corresponds to the sensor's saturation critical point: when the attenuation time exceeds this upper limit, the sensor's internal circuitry may enter a saturation state, or the charge attenuation itself may enter an extremely slow phase, the relationship between attenuation time and charge quantity becomes non-linear, and the measurement resolution decreases. This ideal range can be determined through testing with a standard sample under different environmental conditions. The lower limit is generally set to 10%~20% of the sensor's full scale, and the upper limit is set to 80%~90%. By comparing the acquired historical attenuation times with this range, it can be determined whether the current measurement process is within the sensor's optimal operating range.

[0133] S503: When the historical decay time is lower than the lower limit of the ideal decay time range, the preset charge value will be increased by a preset increment.

[0134] If the historical decay time is less than the lower limit of the ideal range, it indicates that the currently set preset charge value may be too low. This is because in step S1012, the decay time is the time it takes for the charge to decay from the initial monitored value to the preset charge value. If the preset charge value is set too low, the charge can cross this threshold in a very short time, resulting in an overall shorter measured decay time. To correct this, the control terminal performs an upward adjustment operation, adding a fixed-amplitude preset increment to the current preset charge value, such as 1% of the full scale or one absolute charge unit, thereby raising the decay termination threshold. The preset increment is typically set to 2% to 5% of the current preset charge value, and the new preset charge value after the adjustment should not exceed 90% of the initial monitored value to avoid the starting and ending points being too close, resulting in an excessively narrow measurement window. After the adjustment, the charge needs a longer time to decrease to the new, higher preset charge value, and the resulting decay time will be correspondingly extended, thus moving closer to the ideal range.

[0135] S504: When the historical decay time is higher than the upper limit of the ideal decay time range, the preset charge value is lowered by a preset increment. The preset charge value is the charge threshold used to determine the start and end of the decay time in the decay data. Adjusting or lowering the preset charge value makes the measurement window of the decay time expand or contract within the ideal decay time range.

[0136] Conversely, if the historical decay time exceeds the upper limit of the ideal range, it indicates that the current preset charge value may be set too high. An excessively high termination threshold means the charge amount fails to be surpassed even after a considerable time, resulting in a prolonged measured decay time. The sensor may operate in the low-sensitivity region at the end of the response, or even approach saturation. In this case, the control terminal performs a downward adjustment, subtracting the same preset increment from the preset charge value, thereby lowering the termination threshold. After the adjustment, the charge amount decays to the threshold more quickly, and the decay time is correspondingly shortened, causing the measurement window to shrink back to the sensor's linear sensitivity region. The downward adjustment must also ensure that the preset charge value is not lower than 0 and is higher than the system noise level. Through this adaptive mechanism, the measurement window always automatically expands and contracts within the ideal range.

[0137] In addition, as an alternative or supplementary solution to the above adaptive adjustment, a temperature and humidity sensor can be added near the measurement point to monitor the ambient temperature and humidity in real time and correct the first mapping data online: the decay time is multiplied by a compensation factor obtained from a temperature and humidity lookup table to eliminate the influence of environmental changes on the charge decay rate. This compensation factor can be obtained by pre-calibrating in the environmental testing chamber.

[0138] Based on the same inventive concept, please refer to Figure 4 This application also proposes an intelligent rewinding control system for spunlace nonwoven fabric, characterized in that it includes an electrostatic sensor, a rewinding roller, a high-voltage power supply disposed on the rewinding roller, and a control terminal. The system comprises:

[0139] The first determining module is used to determine the real-time tension of the spunlace nonwoven fabric based on the decay time of the charge carried by the spunlace nonwoven fabric during the rewinding process, including:

[0140] The first acquisition module is used to acquire data on the attenuation of charge on the spunlace nonwoven fabric over time as it passes through the measurement point, based on an electrostatic sensor.

[0141] The second determining module is used to determine the time taken for the charge to decay from the initial monitoring value to the preset charge value from the decay data as the decay duration.

[0142] The comparison module is used to compare the attenuation time with a preset first mapping data table to determine the real-time tension corresponding to the attenuation time.

[0143] The third acquisition module is used to determine the electrostatic field strength applied to the surface of the rewinding roll based on the real-time tension.

[0144] The control module is used to control the output voltage of the high-voltage power supply based on the electrostatic field strength.

[0145] Based on the same inventive concept, embodiments of this application also propose a processing apparatus, which includes:

[0146] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the intelligent rewinding control method for spunlace nonwoven fabric according to the embodiments of this application.

[0147] In addition, to achieve the above objectives, embodiments of this application also propose a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the intelligent rewinding control method for spunlace nonwoven fabrics according to embodiments of this application.

[0148] The following is combined Figure 5 A detailed description of each component of the processing equipment 500 is provided below:

[0149] The processor 501 is the control center of the processing device 500. It can be a single processor or a collective term for multiple processing elements. For example, the processor 501 can be one or more central processing units (CPUs), application-specific integrated circuits (ASICs), or one or more integrated circuits configured to implement embodiments of the present invention, such as one or more digital signal processors (DSPs), or one or more field-programmable gate arrays (FPGAs).

[0150] Optionally, the processor 501 can perform various functions of the processing device 500 by running or executing software programs stored in the memory 502 and by calling data stored in the memory 502.

[0151] In a specific implementation, as one example, the processor 501 may include one or more CPUs, for example... Figure 5 CPU0 and CPU1 are shown in the diagram.

[0152] In a specific implementation, as one embodiment, the processing device 500 may also include multiple processors. Each of these processors may be a single-core processor (single-CPU) or a multi-core processor (multi-CPU). Here, a processor may refer to one or more devices, circuits, and / or processing cores used for processing data (e.g., computer program instructions).

[0153] The memory 502 is used to store the software program that executes the solution of the present invention, and the processor 501 controls its execution. The specific implementation method can be referred to the above method embodiment, and will not be repeated here.

[0154] Optionally, memory 502 may be read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, or electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital universal optical discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, but not limited thereto. Memory 502 may be integrated with processor 501 or exist independently, and may be accessed through the interface circuit of processing device 500. Figure 5 (Not shown in the image) is coupled to processor 501, but this embodiment of the invention does not specifically limit this.

[0155] Transceiver 503 is used for communication with other processing devices. For example, if processing device 500 is a terminal, transceiver 503 can be used to communicate with a network device or with another terminal device. As another example, if processing device 500 is a network device, transceiver 503 can be used to communicate with a terminal or with another network device.

[0156] Alternatively, transceiver 503 may include a receiver and a transmitter. Figure 5 (Not shown separately). The receiver is used to implement the receiving function, and the transmitter is used to implement the transmitting function.

[0157] Optionally, the transceiver 503 can be integrated with the processor 501, or it can exist independently and be connected via the interface circuit of the processing device 500. Figure 5 (Not shown in the image) is coupled to processor 501, but this embodiment of the invention does not specifically limit this.

[0158] Understandable, Figure 5 The structure of the processing device 500 shown does not constitute a limitation on the processing device. The actual processing device may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0159] Furthermore, the technical effects of the processing device 500 can be referred to the technical effects of the methods in the above method embodiments, and will not be repeated here.

[0160] It should be understood that the processor in the embodiments of the present invention can be a central processing unit (CPU), or it can be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0161] It should also be understood that the memory in the embodiments of the present invention can be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory. The non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), or flash memory. The volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of random access memory (RAM) are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDRSDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous linked dynamic random access memory (SLDRAM), and direct rambus RAM (DRRAM). The above embodiments can be implemented, in whole or in part, by software, hardware (such as circuitry), firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the flow or function according to embodiments of the present invention is produced. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. Computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another via wired (e.g., infrared, wireless, microwave, etc.) means. A computer-readable storage medium can be any available medium that a computer can access, or a data storage device such as a server or data center that includes one or more sets of available media. Available media can be magnetic media (e.g., floppy disks, hard disks, magnetic tapes), optical media (e.g., DVDs), or semiconductor media. Semiconductor media can be solid-state drives (SSDs).

[0162] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0163] In this invention, "at least one" refers to one or more items, and "more than one" refers to two or more items. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. It should be understood that in various embodiments of this invention, the sequence number of the above processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this invention.

[0164] 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.

Claims

1. A method for intelligent rewinding control of spunlace nonwoven fabric, characterized in that, An intelligent rewinding control system for spunlace nonwoven fabric is provided. The system includes an electrostatic sensor, a rewinding roller, a high-voltage power supply disposed on the rewinding roller, and a control terminal. The method is executed by the control terminal and includes: The real-time tension of the spunlace nonwoven fabric is determined based on the decay time of the charge carried by the fabric during the rewinding process, including: The data on the attenuation of charge on the spunlace nonwoven fabric over time as it passes through the measurement point are obtained based on the electrostatic sensor. The time taken for the charge to decay from the initial monitoring value to the preset charge value is determined from the decay data as the decay duration; The attenuation duration is compared with a preset first mapping data table to determine the real-time tension corresponding to the attenuation duration; The electrostatic field strength applied to the surface of the rewinding roll is determined based on the real-time tension. The output voltage of the high-voltage power supply is controlled based on the electrostatic field strength.

2. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 1, characterized in that, Determining the intensity of the electrostatic field applied to the surface of the rewinding roll based on the real-time tension includes: The real-time tension is compared with the target tension to obtain the deviation. The corresponding electrostatic field strength is retrieved from a preset second mapping data table based on the deviation.

3. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 2, characterized in that, The first mapping data is established in the following way: The spunlace nonwoven fabric of the same batch is cut into calibration sample fabrics, and the calibration sample fabrics are fixed in a calibration device, wherein the calibration device includes an application electrode plate and a ground electrode plate arranged in parallel, and the calibration sample fabrics are located between the application electrode plate and the ground electrode plate; Multiple calibration voltages of known amplitude are output to the applied electrode plate, so that the calibration sample cloth is subjected to multiple corresponding known electrostatic forces, wherein each of the known electrostatic forces is equivalent to a known calibration tension; The time it takes for the charge amount of the calibration sample fabric corresponding to each known calibration tension to decay from the initial monitoring value to the preset charge value is obtained and determined as the calibration decay time; The known calibration tension is paired with the corresponding calibration attenuation time to form the first mapping data table.

4. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 3, characterized in that, The second mapping data is established in the following way: While the spunlace nonwoven fabric is being rewound at a constant speed and under the target tension, the high-voltage power supply is controlled to output a test voltage so that a test electrostatic field with a step increase is generated on the surface of the rewinding roller. During the electrostatic field test, the charge decay time change of the spunlace nonwoven fabric is obtained, and the charge decay time change is converted into a tension response curve based on the first mapping data table; The tension peak and settling time are identified from the tension response curve, and the mapping relationship between the electrostatic field strength and the tension deviation is determined based on the offset of the tension peak relative to the target tension and the step amplitude of the test electrostatic field strength. Multiple sets of data are obtained based on multiple different step amplitude values ​​of the test voltage, thereby generating the second mapping data table.

5. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 1, characterized in that, The method further includes: The real-time travel speed of the spunlace nonwoven fabric at the measurement point is obtained; Based on the real-time travel speed, a speed fluctuation sequence is determined, and the speed peak value and corresponding first timestamp in the speed fluctuation sequence are obtained; Based on the decay duration, a decay duration fluctuation sequence is determined, and the decay duration extreme value and the corresponding second timestamp in the decay duration fluctuation sequence are obtained; The first timestamp and the second timestamp within the same time period are compared to determine the time difference; When the absolute value of the time difference is less than a preset time correlation threshold, it is determined that the fluctuation of the decay duration is caused by the fluctuation of the real-time travel speed. The coupling coefficient is determined based on the amplitude ratio between the peak velocity and the extreme value of the decay time; Based on the coupling coefficient, the fluctuation of the real-time travel speed is converted into a decay time compensation amount; Subtract the attenuation duration compensation amount from the current attenuation duration to obtain the compensated attenuation duration; The real-time tension is determined based on the compensated attenuation duration and the first mapping data table.

6. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 5, characterized in that, The coupling coefficient is determined based on the amplitude ratio between the peak velocity and the extreme value of the decay time, including: Obtain the peak speed and the corresponding extreme value of the decay duration within multiple different time periods; Obtain the amplitude ratio of each pair of the velocity peak and the extreme value of the decay time to obtain multiple amplitude ratio samples; The average value of the remaining amplitude ratio samples is determined as the coupling coefficient by removing samples that exceed a preset discrete range.

7. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 5, characterized in that, Based on the coupling coefficient, the fluctuation of the real-time travel speed is converted into an attenuation duration compensation amount, including: The speed deviation of the real-time travel speed relative to the reference speed is obtained; Multiply the speed deviation by the coupling coefficient to obtain the initial compensation amount; The transport delay time between the hydroentangled nonwoven fabric passing through the measurement point and reaching the rewinding roller is obtained; The initial compensation amount is time-aligned based on the transmission delay time to generate the attenuation duration compensation amount.

8. The intelligent rewinding control method for spunlace nonwoven fabric according to claim 1, characterized in that, The method further includes: Within the time interval between two consecutive determinations of the attenuation duration, at least one determined historical attenuation duration is obtained; The historical decay time is compared with a preset ideal decay time range, wherein the lower limit of the ideal decay time range corresponds to the lower limit of the response sensitivity of the electrostatic sensor, and the upper limit corresponds to the upper limit of the response saturation of the electrostatic sensor. When the historical decay duration is lower than the lower limit of the ideal decay duration range, the preset charge value is increased by a preset increment. When the historical decay duration is higher than the upper limit of the ideal decay duration range, the preset charge value is lowered by a preset increment, wherein the preset charge value is the charge threshold used to determine the start and end of the decay duration in the decay data. The preset charge value is adjusted up or down to make the measurement window of the decay duration expand or contract within the ideal decay duration range.

9. A smart rewinding control system for spunlace nonwoven fabric, characterized in that, The system includes an electrostatic sensor, a rewinding roll, a high-voltage power supply installed on the rewinding roll, and a control terminal. The first determining module is used to determine the real-time tension of the spunlace nonwoven fabric based on the decay time of the charge carried by the spunlace nonwoven fabric during the rewinding process, including: The first acquisition module is used to acquire data on the attenuation of the charge on the spunlace nonwoven fabric over time as it passes through the measurement point, based on the electrostatic sensor. The second determining module is used to determine from the attenuation data the time it takes for the charge to decay from the initial monitoring value to a preset charge value as the attenuation duration; The comparison module is used to compare the attenuation duration with a preset first mapping data table to determine the real-time tension corresponding to the attenuation duration. The third acquisition module is used to determine the electrostatic field strength applied to the surface of the rewinding roll based on the real-time tension. A control module is used to control the output voltage of the high-voltage power supply based on the electrostatic field strength.

10. A processing apparatus, characterized in that, The processing equipment includes: At least one processor; And, a memory communicatively connected to at least one of the processors; The memory stores instructions that can be executed by at least one processor, which are executed by at least one processor to enable the at least one processor to perform the intelligent rewinding control method for spunlace nonwoven fabric as claimed in any one of claims 1-8.

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