Cast film dynamic deviation rectification control method and system

Abstract

The invention discloses a cast film dynamic deviation rectification control method and system, and relates to the technical field of cast film production, and the method comprises the following steps: collecting a working state signal of external process equipment influencing a deviation rectification system; judging whether the working state of the external process equipment is changed or not based on the working state signal; if it is judged that the working state is a non-starting state, the deviation correction executing mechanism is set to be in a first control mode; if it is judged that the working state is changed into the starting state, the deviation rectifying executing mechanism is switched to a second control mode from a first control mode; and if it is judged that the working state is changed into a complete state, the deviation rectifying executing mechanism is switched to the first control mode from the second control mode. According to the embodiment of the invention, when the working state of the external process equipment is changed, the production quality and efficiency of the cast film are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of cast film production, and in particular to a cast film dynamic deviation correction control method and system. Background Art

[0002] In the cast film production process of wide-width polymer films, in order to ensure neat winding and smooth progress of downstream processes, a correction control system is usually required to correct the lateral deviation of the film on the conveyor path in real time. This type of system generally detects the actual position of the film through edge sensors and drives a swingable guide roller to apply a lateral force to pull the film back to the preset center line. However, in some production processes with special requirements for product performance, in addition to the slow and continuous overall deviation that may be caused by the material properties of the film itself, other production processes may also be introduced. The intervention of these processes will cause additional, atypical interference to the film's morphology, thus posing a severe challenge to conventional correction control logic.

[0003] For example, to form a specific optical crystal structure within the film, the cooling process does not occur naturally in a temperature-controlled environment. Instead, a row of independent high-pressure air cooling nozzles is installed along one side of the film's travel direction in a specific section after the film's initial solidification. These nozzles are arranged perpendicular to the film surface and spaced apart to provide rapid, uneven forced cooling of the film surface. The cooling system operates intermittently, triggered by temperature distribution data on the film surface. When the accumulated heat on one side of the film reaches a preset value, the row of nozzles activates simultaneously and instantly, ejecting high-pressure airflow.

[0004] Because the nozzles are discrete, they produce not a uniform curtain of air but multiple, independent jets of air impacting the wide film surface. This impact creates a complex, nonlinear morphology at the film's edge. Instead of a single, horizontal motion, the film edge is shaped by these air currents into a wavy profile, concave inwards directly opposite the nozzles and convex between them. When the cooling system activates, the corresponding airflow creates a deep "trough" in the sensor's detection area, instantly shifting the edge position far beyond its normal range for slow deflection and triggering a significant, critical deflection alarm. The control system, upon receiving this value, is unable to determine its source. Its program logic dictates that the greater the deflection, the faster and more dramatic the corrective action should be. Therefore, the system immediately commands the guide roller to swing to its maximum designed angle and speed.

[0005] However, the guide roller's oscillation acts across the entire width of the film, applying a uniform tension across the entire web. This global correction creates a disastrous mismatch with the localized wave-like deformation at the film's edges. At the "trough" where the sensor is located, the film is already concave due to airflow impact, and now, under the strong pull of the guide roller, the tension in this area suddenly increases dramatically, causing excessive stretching. Meanwhile, at the adjacent "peak," where the film is already relatively convex, the guide roller's overall pull exacerbates this relaxation, leading to material accumulation. This extreme combination of "overstretching at one end and slack accumulation at the other" occurring simultaneously and across different widths creates significant, uneven internal stresses in the film. As the film continues to roll and eventually cools and sets, these internal stresses solidify, forming several permanent longitudinal wrinkles across the entire web. Ultimately, this "correction" by the web-correction system, far from resolving the problem, became the direct cause of widespread defective products. Summary of the Invention

[0006] The purpose of this application is to provide a dynamic correction control method and system for cast film, which solves the problem that when the working state of external process equipment changes, the traditional correction system cannot identify abnormal interference, resulting in wrinkles or defective products in the film, and significantly improves the quality and efficiency of cast film production.

[0007] The present application provides a cast film dynamic deviation correction control method, comprising:

[0008] Collect working status signals of external process equipment that affect the correction system;

[0009] Determine whether the working state of the external process equipment has changed based on the working state signal;

[0010] If the working state is determined to be the unstarted state, the deviation correction actuator is set to the first control mode, and the deviation correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film;

[0011] If it is determined that the working state has changed to the start-up state, the correction actuator is switched from the first control mode to the second control mode. The correction actuator terminates the closed-loop control of the correction actuator based on the second control mode and maintains the correction actuator in the protective control state. The protective control state is the process in which the correction actuator waits for the external process equipment to complete the changed working state.

[0012] If the working state is determined to be completed, the correction actuator is switched from the second control mode to the first control mode, and the correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film.

[0013] The above solution solves the problem of wrinkles or defective films caused by the traditional correction system's inability to identify abnormal interference when the working state of external process equipment changes, thereby improving the robustness of correction and film production quality.

[0014] Furthermore, the correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film, including:

[0015] Collect actual position data of the film based on edge sensors;

[0016] Based on the actual position data, the pivotable guide roller is driven to apply a lateral force component to the film.

[0017] Through the above scheme, the specific closed-loop control method of the correction actuator in the first control mode is clarified, ensuring the accurate lateral deviation compensation of the film under normal conditions.

[0018] Furthermore, switching the deviation-correcting actuator from the second control mode to the first control mode includes:

[0019] When it is detected that the working state changes to the completion state, the delay period set for the deviation correction execution mechanism is extracted;

[0020] The deviation correction actuator is controlled to switch from the second control mode to the first control mode based on the delay period.

[0021] Through the above solution, a delay period control is introduced to avoid resuming the correction immediately when the state of the external process equipment has just changed, thereby preventing incorrect correction caused by transient instability.

[0022] Furthermore, controlling the deviation correction actuator to switch from the second control mode to the first control mode based on the delay period includes:

[0023] Collect a set of location data based on edge sensors;

[0024] Calculate the fluctuation characteristic value of the degree of dispersion of a set of position data;

[0025] Determine whether the fluctuation characteristic value meets the preset stability condition of the stable state threshold value;

[0026] When the fluctuation characteristic value meets the preset stability condition, the delay period ends, and the deviation correction execution mechanism is controlled to switch from the second control mode to the first control mode.

[0027] Through the above scheme, by collecting position data and calculating the fluctuation characteristic value to determine whether the film state is stable, the intelligent and precise recovery of the correction system is achieved, avoiding premature or late recovery of correction.

[0028] Furthermore, calculating the fluctuation characteristic value of the discrete degree of a set of position data includes:

[0029] Sort a set of position data;

[0030] Eliminate a preset number of extreme value data from a group of position data that has completed sorting processing to form a core data group;

[0031] Calculate the fluctuation characteristic value of the degree of dispersion of a set of position data based on the core data set.

[0032] Through the above scheme, the fluctuation characteristic value is calculated by eliminating extreme value data, which effectively eliminates the influence of occasional interference on the calculation of the fluctuation characteristic value and improves the accuracy of stable state judgment.

[0033] Furthermore, determining whether the fluctuation characteristic value satisfies a preset stability condition of a stable state threshold value includes:

[0034] In a first control mode, obtaining a set of edge sensor position data representing a baseline noise level;

[0035] Calculating a baseline fluctuation value based on edge sensor position data of a baseline noise level;

[0036] determining a steady-state threshold value based on the baseline fluctuation value;

[0037] Based on the stable state threshold value, it is determined whether the fluctuation characteristic value meets the preset stability condition.

[0038] Through the above solution, a method for dynamically determining the stable state threshold value based on the baseline noise level is provided, so that the judgment of the stable state is more adaptable to changes in the actual production environment and the adaptability of the system is improved.

[0039] Furthermore, determining the steady state threshold value based on the baseline fluctuation value includes:

[0040] Performing a calibration operation on a preset film type to obtain a baseline fluctuation reference value of the preset film type and obtaining recovery characteristic data of the preset film type after an external process device stops functioning;

[0041] Establishing a relationship set of steady-state threshold values ​​based on baseline fluctuation reference values ​​and recovery characteristic data;

[0042] A steady state threshold value is determined based on the baseline fluctuation value and the relationship set.

[0043] Through the above scheme, by calibrating different film types and establishing a relationship set, the determination of the stable state threshold value can be personalized according to the film type and recovery characteristics, further improving the accuracy and applicability of the correction.

[0044] Furthermore, the relationship set for establishing the stable state threshold value based on the baseline fluctuation reference value and the recovery characteristic data includes:

[0045] When performing a calibration operation on the preset film type, a set of calibration data corresponding to a plurality of preset process parameter points is obtained, wherein each calibration data in the set of calibration data includes a baseline fluctuation reference value and recovery characteristic data obtained at the preset process parameter point;

[0046] Determining a target stable state threshold value associated with a preset process parameter point corresponding to each calibration data, wherein the target stable state threshold value is used to establish a multi-point correspondence relationship between the preset process parameter point and the target stable state threshold value, and the relationship set includes the multi-point correspondence relationship;

[0047] Get the current process parameter values;

[0048] The stable state threshold value is determined based on the current process parameter value and the multi-point correspondence relationship.

[0049] Through the above scheme, the process of establishing the relationship set is further refined, and the stable state threshold value is determined by the multi-point correspondence relationship and the current process parameter value, so that the system can perform more precise control according to the specific process parameters, thereby improving the intelligent level of correction.

[0050] Furthermore, obtaining recovery characteristic data of a preset film type after the external process equipment stops functioning includes:

[0051] After the external process equipment stops functioning, a series of position data output by the edge sensor is collected to form a recovery process data sequence;

[0052] Determining characteristic parameters of the reaction recovery dynamic process based on the recovery process data sequence;

[0053] The characteristic parameters are used as the restored characteristic data.

[0054] Through the above scheme, the method of obtaining recovery characteristic data is clarified. By analyzing the characteristic parameters of the recovery process data sequence, the recovery of the film after external interference can be more accurately evaluated, providing a reliable basis for determining the stable state threshold value.

[0055] Accordingly, the present invention also provides a cast film dynamic deviation correction control system comprising:

[0056] Status acquisition module, used to collect working status signals of external process equipment that affect the correction system;

[0057] A status judgment module is used to judge whether the working status of the external process equipment has changed based on the working status signal;

[0058] A first control module is configured to set the deviation correction actuator to a first control mode when determining that the working state is an inactive state, so that the deviation correction actuator performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film;

[0059] a second control module configured to switch the correction actuator from the first control mode to the second control mode when determining that the working state has changed to the start-up state, wherein the correction actuator terminates the closed-loop control of the correction actuator based on the second control mode and maintains the correction actuator in a protective control state, wherein the protective control state is a process in which the correction actuator waits for the external process equipment to complete the changed working state;

[0060] The third control module is used to switch the correction actuator from the second control mode to the first control mode when it is determined that the working state changes to the completion state. The correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film.

[0061] To sum up, the present application provides a dynamic correction control method and system for cast film, which dynamically monitors the working status of external process equipment and intelligently switches the correction mode when the equipment starts or completes the change, thereby avoiding the misoperation of the traditional correction system under external interference, thereby effectively preventing the film from wrinkling and defective products. It solves the problem that when the working status of external process equipment changes, the traditional correction system cannot identify abnormal interference, resulting in wrinkles or defective products in the film, and significantly improves the quality and efficiency of cast film production. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] Figure 1 is a flow chart of a cast film dynamic deviation correction control method in an embodiment of the present invention;

[0064] Figure 2 is a flow chart of a method for calculating a fluctuation characteristic value of a degree of dispersion of a set of position data in an embodiment of the present invention;

[0065] Figure 3 It is a schematic structural diagram of a cast film dynamic deviation correction control system in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0067] The technical core of the embodiment of the present invention is that when the external process equipment (such as the cooling nozzle) is started, the operation of the correction system is simply suspended. However, this direct suspension method will cause the film to lose its correction ability during the suspension period, and its inherent slow overall deviation will not be compensated, which may cause the film to deviate from the center line or even touch the edge of the equipment, causing new production problems. To this end, the present application can be set to allow the correction system to enter a "protective" state when the external process equipment is started, neither performing erroneous closed-loop corrections nor waiting for the external interference to end. This protective state requires the correction actuator to terminate its conventional closed-loop control to avoid applying mismatched correction forces to the film. At the same time, when the external process equipment completes its work and returns to stability, the correction system should be able to return to the normal closed-loop control mode in a timely and smooth manner to continue compensating for the overall lateral deviation of the film. This dynamic mode switching requires the system to be able to sense the working status of the external process equipment in real time and intelligently adjust the correction strategy accordingly, so as to avoid damage caused by local interference while ensuring the overall position of the film. The present invention relates to a method for controlling the dynamic deviation correction of a cast film. The method collects working status signals of external process equipment that affects the deviation correction system; determines whether the working status of the external process equipment has changed based on the working status signals; if the working status is determined to be inactive, sets the deviation correction actuator in a first control mode, and performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film; if the working status is determined to be active, switches the deviation correction actuator from the first control mode to a second control mode, and terminates the closed-loop control of the deviation correction actuator based on the second control mode, and maintains the deviation correction actuator in a protective control state, which is the process in which the deviation correction actuator waits for the external process equipment to complete the change in working status; if the working status is determined to be complete, switches the deviation correction actuator from the second control mode to the first control mode, and performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film. The above method solves the problem that when the working status of the external process equipment changes, the traditional deviation correction system cannot identify abnormal interference, resulting in wrinkles or defective products in the film, thereby improving the robustness of the deviation correction and the quality of film production.

[0068] Specifically, Figure 1The flowchart of the cast film dynamic deviation correction control method in an embodiment of the present invention is shown. This method intelligently senses the working status of external process equipment and dynamically adjusts the control mode of the deviation correction actuator, thereby effectively avoiding the misjudgment and error correction of traditional deviation correction systems in complex production environments. The method includes the following steps:

[0069] S101, collecting working status signals of external process equipment that affect the correction system;

[0070] It should be noted that step S101 is always in working state to control the control mode of the correction actuator, that is, when the external process equipment is not in working state, the correction actuator is always in the first control mode state, and when the external process equipment is in working state (the working state is from the start state to the completion state), the correction actuator is always in the second control mode state.

[0071] The operating status signal of external process equipment refers to a signal used to indicate the operating status of other production units that may have an instantaneous or local impact on the film's shape or position during the cast film production process, in addition to the correction system itself. It can take various forms, such as digital signals, analog signals, communication protocol data, etc. Specifically, it can be the start and stop signal of the cooling nozzle, the power signal of the heating unit, the speed change signal of the pulling roller, etc. Its main purpose is to provide a basis for the correction system to switch the control mode. The correction actuator refers to a mechanical or electrical device responsible for adjusting the lateral position of the film on the cast film production line. It can adopt various structures, such as a swingable guide roller, a laterally movable winding shaft, a tension-adjustable pulling roller group, etc. Its main purpose is to apply force to correct the lateral deviation of the film based on the detected film position deviation.

[0072] S102, judging whether the working state of the external process equipment has changed based on the working state signal;

[0073] It should be noted that step S102 judges the current working status of the external process equipment through the working status signal collected in real time. If it is judged that the working status of the external process equipment is not in progress, it enters S103. If it is judged that the working status of the external process equipment has just started, it enters S104. If it is judged that the external process equipment has completed the work from startup, it enters S105.

[0074] S103, setting the deviation correction actuator to the first control mode;

[0075] Specifically, if the operating state is determined to be inactive, the deflection correction actuator is set to the first control mode, and the deflection correction actuator performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film. It should also be noted that while step S103 is still being executed, it is also necessary to collect the operating status signal of the external process equipment based on step S101 and re-enter the determination process of step S102.

[0076] The first control mode refers to the operating mode in which the correction actuator performs real-time, continuous position correction of the film under normal production conditions. This mode can be implemented using a variety of control algorithms, such as proportional-integral-derivative (PID), fuzzy control, and adaptive control. Its primary purpose is to continuously compensate for the film's overall lateral deviation through a closed-loop feedback mechanism, ensuring that the film operates stably along the preset path.

[0077] When external process equipment is not activated, meaning it is not causing any additional interference to the film, the deflection actuator is set to the first control mode. In this mode, the deflection actuator performs closed-loop control, continuously compensating for the film's overall lateral deviation to ensure stable film operation.

[0078] S104, switching the deviation correction actuator from the first control mode to the second control mode;

[0079] Specifically, if the operating state is determined to be the start-up state, the correction actuator is switched from the first control mode to the second control mode. Based on the second control mode, the correction actuator terminates closed-loop control of the correction actuator and maintains the correction actuator in a protective control state. The protective control state is the process in which the correction actuator waits for the external process equipment to complete the changed operating state. It should also be noted that while continuing to execute step S104, it is also necessary to collect the operating state signal of the external process equipment based on step S101 and re-enter the judgment process of S102.

[0080] The second control mode refers to an operating mode in which the correction actuator suspends conventional closed-loop control and enters a special response state when the external process equipment starts or changes. The second control mode can be implemented by means of preset position holding, output locking, low gain control, etc., which is mainly to avoid the correction system from making improper correction actions due to misjudgment during external interference, thereby protecting the film from damage. The protective control state refers to a non-active correction but standby state maintained by the correction actuator in the second control mode. It can be manifested as locking the correction actuator in the current position, returning it to a preset safe position, or keeping its output at a constant value, etc., which is mainly to prevent the correction actuator from applying erroneous or destructive correction forces to the film during changes in the working state of the external process equipment, while waiting for the external interference to end and preparing for the resumption of normal correction.

[0081] If the system determines that the operating state of the external process equipment has changed to the active state, indicating the possibility of localized film disturbance, the corrective actuator immediately switches from the first control mode to the second. In the second control mode, the corrective actuator's closed-loop control is suspended and maintained in a protective control state. This protective control state allows the corrective actuator to wait for the external process equipment to complete its post-change operation. This prevents conventional closed-loop control from misjudging the film's morphology and causing non-uniform deformation due to localized disturbances, leading to inappropriate corrective actions that could damage the film.

[0082] S105 , switching the deviation correction actuator from the second control mode to the first control mode.

[0083] Specifically, if the working state is determined to be completed, the correction actuator is switched from the second control mode to the first control mode. The correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film. It should also be noted that while continuing to execute step S105, it is also necessary to collect the working state signal of the external process equipment based on step S101 and re-enter the judgment process of S102.

[0084] Once the external process equipment reaches a complete state, meaning the interfering factor has been eliminated, the system switches the corrective actuator from the second control mode back to the first control mode, resuming closed-loop control of the film and continuing to compensate for the film's overall lateral deflection. This dynamic mode switching mechanism allows the corrective system to flexibly transition between normal operation and responding to external interference, thus avoiding unnecessary damage to the film under complex operating conditions.

[0085] The above method organically combines the real-time acquisition of the working status signals of the external process equipment with the dynamic control mode switching mechanism of the correction actuator. Thus, when the external process equipment causes local and non-uniform interference to the film, the conventional closed-loop correction can be terminated in time and the protective control state can be switched to, thereby effectively avoiding misjudgment of the correction system due to interference from the external process equipment, thereby avoiding damage to the film, ensuring the production of high-quality film products, and achieving the effect of preventing the film from generating destructive stress and permanent wrinkles.

[0086] For example, a cast film production line uses a set of air nozzles for localized forced cooling. The start and stop status of these nozzles is transmitted to the web-correction control system via digital signals. The processor in the web-correction control system continuously receives and analyzes these signals to determine the operating status of the air nozzles. When the air nozzles are inactive, the web-correction actuator, such as a servo-motor-driven swinging guide roller, is set to the first control mode. In this mode, the guide roller adjusts its swing angle in real time through closed-loop PID control based on edge sensor feedback to compensate for the film's slow overall lateral deviation during production. Once the processor detects that the air nozzle's operating status signal has changed to the active state, for example, when all nozzles are activated simultaneously, it immediately instructs the guide roller's servo motor to switch from the first control mode to the second control mode. In the second control mode, the servo motor terminates its closed-loop control and enters a protective control state, such as locking the guide roller in its current position or retracting it to a preset center position. This prevents the web-correction system from making erroneous corrections if the nozzle airflow impact causes localized deformation of the film edge. When the processor detects again that the working status signal of the air nozzle has changed to the completed state, for example, all nozzles are closed, the processor will switch the servo motor of the guide roller from the second control mode back to the first control mode according to the preset logic, and resume the closed-loop correction control of the film. This solution can effectively solve the problem of traditional correction systems causing film damage due to misjudgment when external process equipment (such as local forced cooling nozzles) causes instantaneous, localized, and non-uniform interference to the edge of the film during the production of cast film. By monitoring the working status of external process equipment in real time and dynamically switching the control mode of the correction actuator accordingly, this solution can promptly terminate conventional closed-loop correction when external interference occurs and switch to a protective control state, thereby avoiding the correction actuator from performing inappropriate, overall correction actions during local deformation of the film. This ensures that the correction system can distinguish between local morphological changes and overall position deviations of the film, avoiding the generation of destructive stress inside the film due to the mismatch between the correction action and the deformation morphology, thereby effectively preventing the formation of permanent wrinkles and significantly improving the quality and production stability of cast film products.

[0087] It should be noted that the steps of the correction actuator performing closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film include: collecting the actual position data of the film based on the edge sensor; and driving the swingable guide roller to apply lateral force to the film based on the actual position data.

[0088] Here, the edge sensor refers to a sensor used to detect the edge position of the film, which can be a photoelectric sensor, an ultrasonic sensor or a CCD visual sensor, etc., and its purpose is to obtain the real-time lateral position information of the film; the swingable guide roller refers to a roller that can change the direction of the film by adjusting its inclination angle, which can be a hydraulically driven swing roller, an electric screw-driven swing roller, etc., and its purpose is to apply a lateral force to the film to correct its offset; the lateral component force refers to the force acting in the lateral direction of the film, which can be a lateral pulling force generated by the film tension when the guide roller swings, and its purpose is to guide the film to the preset center position.

[0089] The solution of this application achieves closed-loop control of the film's lateral deviation by introducing a feedback mechanism. Specifically, when the correction actuator is in the first control mode, the edge sensor instantly collects the film's actual position data, which directly reflects the film's current lateral deviation. The control system then calculates the correction amount based on this actual position data and drives the swingable guide roller. The guide roller adjusts its swing angle to apply a calculated lateral force component to the film, thereby guiding the film back to the preset center position.

[0090] This closed-loop control, based on immediate feedback, responds to the film's actual deflection, overcoming the potential for inaccurate control, overshooting, or undershooting associated with traditional open-loop control or control without direct feedback. Using position information provided by edge sensors, the system detects and corrects film deflection, ensuring timely correction. The oscillating guide roller acts as an actuator, converting control commands into physical force to adjust the film's path.

[0091] This closed-loop control mechanism, combined with the dynamic mode switching strategy proposed in the cast film dynamic correction control method, can improve the overall correction performance of the cast film production line. When the external process equipment is in a stable state, the closed-loop control provided by this solution ensures the continuous alignment of the film, providing a benchmark for subsequent processes. When the state of the external process equipment changes, the cast film dynamic correction control method can switch to a protective control state in a timely manner, avoiding invalid or harmful correction operations when the film morphology is unstable. Once the external interference ends, the system can quickly return to the closed-loop control achieved by this solution, thereby continuously ensuring the production quality and efficiency of the film in a production environment with various changes.

[0092] It should be noted that the step of switching the correction execution mechanism from the second control mode to the first control mode in an embodiment of the present invention includes: when it is detected that the working state changes to the completion state, extracting the delay period set for the correction execution mechanism; and controlling the correction execution mechanism to switch from the second control mode to the first control mode based on the delay period.

[0093] The delay period refers to the period of time that the correction actuator waits before switching from the second control mode to the first control mode after detecting that the working state of the external process equipment has changed to the completion state. The delay period can be a preset fixed time, such as a few seconds or tens of seconds. Its purpose is to provide the film with the time required for deformation recovery after the external process equipment has ended, and to avoid the correction system from immediately resuming closed-loop control when the film state is not yet completely stable. In addition, the delay period can also be a time dynamically determined according to the actual state of the film, for example, by monitoring the fluctuation of the edge position of the film to determine whether it has reached a stable state, so as to flexibly adjust the waiting time. Its purpose is to ensure that the correction system will not switch modes until the film state has recovered to a stable level suitable for closed-loop control, thereby avoiding judgment deviations and excessive correction action amplitudes caused by premature switching.

[0094] By introducing a delay period, the timing of the corrective actuator's switch from the second control mode to the first control mode is optimized. When the system detects that the external process equipment's operating status has changed to completion, the corrective actuator no longer immediately switches back to the first control mode. Instead, a preset or dynamically determined delay period is first applied. This delay period provides a buffer for the film after the external process equipment's action ends, allowing sufficient time for local deformation and overall tension distribution to recover and stabilize. Because the film can gradually recover to a relatively stable state during the delay period, the corrective system can switch modes based on the film's state after the delay period expires. This avoids the potential for biased judgment and excessive corrective action caused by closed-loop control during unstable film conditions. Specifically, after the external process equipment completes its operation, the film may still be in an unstable state of deformation or vibration. If the corrective actuator immediately switches from the protective second control mode back to the first control mode for closed-loop control, the data collected by the edge sensor may reflect transient, unstable deformation of the film rather than its actual overall lateral deflection. This can cause the web-correcting system to make excessive corrections, exacerbating uneven stress in the film and even causing permanent wrinkles. By first extracting and applying a delay period upon detecting a change in the working state to completion, the system allows the film's dynamic response to decay until its edge position fluctuations stabilize. Upon expiration of the delay period, the web-correcting actuator is controlled to switch to the first control mode, re-initiating closed-loop control based on stable film position data. This delayed switching mechanism, combined with the overall logic of the cast film dynamic web-correcting control method, which switches modes based on the operating state of external process equipment, ensures that the web-correcting system can smoothly and reliably resume its closed-loop web-correcting function after the external disturbance ends. This effectively avoids film quality issues caused by inappropriate switching timing, improves the stability and accuracy of the entire web-correcting control process, and enhances the reliability and accuracy of web-correcting control. This effectively prevents quality defects such as uneven internal stress and wrinkles in the film caused by inappropriate switching timing, thereby ensuring the production quality and winding uniformity of the cast film.

[0095] For example, when the cast film dynamic web-correction control method detects that the operating status of external process equipment has changed to a completed state—for example, when the cooling nozzle stops spraying air—the system immediately starts an internal timer. This timer is set to a preset delay, for example, 5 seconds. During this 5-second delay, the web-correction actuator remains in the second control mode, maintaining its protective control state, and refraining from closed-loop web-correction. During this period, without the impact of strong external airflow, localized deformation and vibration at the film's edge gradually decay and stabilize. After the 5-second delay expires, the control system issues a command to smoothly switch the web-correction actuator from the second control mode to the first control mode. At this point, the web-correction actuator reactivates its closed-loop control function and begins driving the oscillating guide rollers to compensate for the film's overall lateral deviation based on the film's actual position data collected by the edge sensor. This ensures that the web-correction system resumes normal operation only after the film stabilizes, avoiding the potential adverse effects of web-correction before the film has fully recovered.

[0096] Specifically, the steps of controlling the deviation correction actuator to switch from the second control mode to the first control mode based on the delay period include: collecting a set of position data based on the edge sensor; calculating the fluctuation characteristic value of the discrete degree of a set of position data; judging whether the fluctuation characteristic value meets the preset stability condition of the stable state threshold value; when the fluctuation characteristic value meets the preset stability condition, ending the delay period and controlling the deviation correction actuator to switch from the second control mode to the first control mode.

[0097] Here, a set of position data refers to multiple film edge position measurements continuously collected by the edge sensor over a period of time. Its purpose is to obtain sequential information on the dynamic changes of the film edge, thereby being able to assess the overall stability trend of the film and avoid the transient errors or local interference that may be caused by single-point measurement. The fluctuation characteristic value of the degree of dispersion refers to the value used to quantify the degree to which each data point in a set of position data deviates from its central trend (such as the mean value). It can be a statistical quantity such as standard deviation, variance, range, or mean absolute deviation. Its purpose is to convert the dynamic instability of the film edge into a quantifiable indicator for objective judgment. The stable state threshold value refers to a pre-set critical value used to determine whether the film edge has reached a stable state. It can be an empirical value, a statistical value derived from historical data analysis, or a reference value obtained through system calibration. Its purpose is to provide a clear basis for judging whether the film has recovered from external interference and tended to stabilize. The preset stability condition refers to the logical rule used to determine the relationship between the fluctuation characteristic value and the stable state threshold value. Specifically, the fluctuation characteristic value can be less than or equal to the stable state threshold value. Its purpose is to ensure that the control mode switch is triggered only when the fluctuation level of the film edge is reduced to an acceptable stable level.

[0098] This approach overcomes the limitations of traditional fixed-delay switching modes by introducing real-time monitoring and assessment of the film's actual stability. When the operating status of an external process device changes to a completed state, the system no longer simply waits for a preset fixed delay period, but instead immediately initiates a dynamic assessment process. Specifically, the system continuously collects position data from the film's edge using edge sensors. This data reflects the film's actual fluctuation at the current moment. The system then calculates a fluctuation characteristic value, representing the degree of dispersion of this position data. This characteristic value objectively quantifies the degree of wobble or jitter at the film's edge. The system then compares this calculated fluctuation characteristic value with a pre-set stability threshold to determine whether it meets the preset stability criteria. Only when the fluctuation characteristic value decreases to and meets the stability criteria defined by the stability threshold does it indicate that the film has fully recovered from the impact of the external process device and is approaching stability. At this point, the system immediately ends any existing delay period and controls the correction actuator to switch from the protective second control mode back to the normal closed-loop correction first control mode. Compared to solutions that rely solely on a preset delay period for switching, this method of dynamically determining film stability based on real-time data ensures that the correction system resumes normal operation only after the film is truly stable, rather than simply after the time has expired. This avoids malfunctioning of the correction system due to premature switching before the film has stabilized, which could cause further film deviation or damage; it also avoids production efficiency losses caused by waiting for a fixed delay after the film has already stabilized. In this way, the correction system can respond more intelligently and accurately to changes in external process equipment, thereby optimizing the continuity and stability of the production process while ensuring film quality.

[0099] For example, when external process equipment (e.g., forced cooling nozzles) on a cast film production line completes its operation and ceases function, the web-correction control system initiates a film stability monitoring process. This process continuously collects film edge position data using an edge sensor (e.g., a high-precision CCD line scan camera). Specifically, the CCD line scan camera continuously captures images of the film edge at a rate of 100 frames per second and extracts the lateral position coordinates of the film edge. Every 0.5 seconds, the system extracts a set of position data from the 50 most recently collected position coordinate data points. The control unit then calculates the standard deviation of these 50 position data points as a fluctuation characteristic value indicating the degree of dispersion. For example, if the calculated standard deviation is 0.8 mm, the system compares it with a preset stability threshold (e.g., 0.5 mm). The preset stability condition can be set as the fluctuation characteristic value being less than or equal to the stability threshold. If the currently calculated standard deviation of 0.8 mm does not meet the condition of being less than or equal to 0.5 mm, the system continues monitoring and calculation. When the calculated standard deviation drops to 0.4 mm, satisfying the preset stability condition, the system immediately ends any ongoing delay timer and sends a command to the web-correction actuator to switch from the second control mode back to the first. This allows the web-correction system to accurately resume its normal web-correction function once the film edge fluctuations are truly stable.

[0100] Specifically, Figure 2 The flowchart of the method for calculating the fluctuation characteristic value of the dispersion degree of a set of position data in an embodiment of the present invention is shown, which specifically includes:

[0101] S201, sorting a group of position data;

[0102] Sorting here refers to arranging a set of position data in ascending or descending order according to the value, with the purpose of facilitating the subsequent identification and elimination of outliers in the data.

[0103] S202, removing a preset number of extreme value data from a group of position data that has completed sorting processing to form a core data group;

[0104] Here, extreme value data refers to values ​​that significantly deviate from other data points in the data set, usually caused by factors such as instantaneous sensor failure, environmental interference, or abnormal local deformation of the film. The purpose is to avoid these atypical data from having an undue impact on the overall statistical results. The preset number refers to setting a fixed or adjustable elimination ratio or number based on the actual application scenario, data characteristics, or experience when eliminating extreme value data. The purpose is to retain enough valid data to reflect the true state of the film while effectively suppressing noise. The core data group refers to a data subset formed after a set of position data is sorted and a preset number of extreme value data are eliminated. The purpose is to provide a purer and more representative data basis for subsequent calculation of fluctuation characteristic values.

[0105] S203. Calculate a set of fluctuation characteristic values ​​of the degree of dispersion of position data according to the core data set.

[0106] The fluctuation characteristic value here reflects the stability or fluctuation amplitude of the film position within a specific time period.

[0107] The method according to an embodiment of the present invention preprocesses a set of collected position data to more accurately calculate the degree of dispersion of the film's position. Specifically, the position data is first sorted, laying the foundation for the subsequent identification and location of extreme values ​​within the data. Sorting arranges the data points according to their numerical magnitude, making it easier to identify data points at the ends as potential extreme values. Secondly, a predetermined number of extreme value data points are removed from the sorted data to form a core data set. This step is a critical data cleaning process, effectively eliminating atypical data points caused by factors such as sensor noise, transient interference, or abnormal local deformation of the film. If these extreme value data points are directly included in the calculation, they can significantly distort the true reflection of the fluctuation characteristic value, leading to misjudgment of the film's stable state. By eliminating these data points, the subsequent calculations are based on a more representative dataset that more accurately reflects the overall deflection state of the film. Finally, based on this cleaned core data set, a set of fluctuation characteristic values ​​for the degree of dispersion of the position data is calculated. Because the data used in the calculation has been free of interference factors, the resulting fluctuation characteristic values ​​more accurately reflect the actual fluctuation of the film. This data preprocessing method, combined with the previously proposed method of determining whether the fluctuation characteristic value meets the preset stability threshold, significantly improves the accuracy and stability of the corrective control. When the external process equipment changes its operating state to "completed," the system needs to determine whether the film has returned to a stable state so that it can switch the corrective actuator from the protective second control mode back to the precise closed-loop first control mode. The more accurate fluctuation characteristic values ​​obtained by this solution enable the system to more reliably determine whether the film has truly stabilized, avoiding misjudgments caused by abnormal data. For example, when localized wavy deformation occurs at the edge of a film, conventional fluctuation characteristic values ​​may be inflated by a few extreme readings, causing the system to mistakenly believe that the film is still unstable and delay the switch, or even operate in the unstable second control mode for an extended period of time. By eliminating extreme values ​​caused by these localized deformations, this solution enables the fluctuation characteristic values ​​to more accurately reflect the overall lateral deviation stability of the film. This allows the system to promptly switch back to the first control mode when the film is truly stable, avoiding unnecessary delays or inaccurate control, and ensuring the quality and stability of the film throughout the production process.

[0108] For example, when calculating the fluctuation characteristic value of the degree of dispersion of a set of position data, one can first collect, for example, 100 film edge position data points to form a raw data sequence. Next, these 100 data points are sorted, perhaps using a quick sort or merge sort algorithm to arrange the data in ascending order. For example, if the raw data is [50.1, 50.5, 49.8, 50.0, 55.0, 49.9, 50.2, 45.0, ...], after sorting it might become [45.0, 49.8, 49.9, 50.0, 50.1, 50.2, 50.5, 55.0, ...]. Then, a predetermined number of extreme value data points are removed from the sorted data to form a core data set. For example, one can pre-determine the number of extreme value data points, i.e., the smallest 2.5% and the largest 2.5% of the data points, to be removed. For 100 data points, this means eliminating the 2-3 smallest values ​​and the 2-3 largest values. In the sorted example above, 45.0 and 55.0 might be identified as extreme values ​​and eliminated. After these eliminations, the remaining data points constitute the core data set. For example, after eliminating 45.0 and 55.0, the core data set would be [49.8, 49.9, 50.0, 50.1, 50.2, 50.5, ...]. Finally, based on this core data set, a set of fluctuation characteristic values ​​representing the degree of dispersion of the position data is calculated. The standard deviation can be used as the fluctuation characteristic value, that is, the square root of the average of the squared deviations between all data points in the core data set and the mean of the core data set is calculated. In this way, the calculated fluctuation characteristic value can more accurately reflect the position fluctuation of the film under normal conditions, avoiding interference from abnormal data on the judgment results.

[0109] It should be noted that the steps for determining whether the fluctuation characteristic value satisfies the preset stability condition of the stable state threshold value include: in the first control mode, obtaining a set of edge sensor position data for representing the baseline noise level; calculating the baseline fluctuation value based on the edge sensor position data of the baseline noise level; determining the stable state threshold value based on the baseline fluctuation value; and determining whether the fluctuation characteristic value satisfies the preset stability condition based on the stable state threshold value.

[0110] The baseline noise level here refers to the degree of random fluctuation inherent in the film position data collected by the edge sensor when the correction system is in a normal closed-loop control state (i.e., the first control mode), caused by factors such as equipment vibration, airflow disturbance, or slight material non-uniformity. It can be represented by edge sensor position data continuously collected for a period of time during stable operation. Its purpose is to provide an objective reference benchmark for the subsequent dynamic adjustment of the stable state threshold value. The baseline fluctuation value here refers to a quantitative representation of the degree of discreteness of the edge sensor position data of the baseline noise level. It can be calculated using statistical methods such as standard deviation, variance, mean absolute deviation, or range. Its purpose is to convert the complex noise level into a quantifiable value to facilitate subsequent logical judgment and threshold value setting. The stable state threshold value here refers to a critical value used to determine whether the film fluctuation characteristic value has reached a stable state. It can be dynamically generated based on the baseline fluctuation value through a preset functional relationship, lookup table, or machine learning model. Its purpose is to enable the correction system to adaptively adjust the judgment standard according to the noise level of the actual production environment to avoid misjudgment or hysteresis caused by a fixed threshold value.

[0111] The method for dynamically determining a stable state threshold value in an embodiment of the present invention effectively addresses the instability of the correction system caused by traditional fixed threshold values ​​in complex production environments. Specifically, when the correction actuator is in the first control mode, the system first acquires a set of edge sensor position data. This data represents the baseline noise level of the film under normal, stable operating conditions. By calculating this baseline noise level data, a baseline fluctuation value is obtained, which quantifies the inherent fluctuation of the film edge under the current production environment. Based on this real-time calculated baseline fluctuation value, the system can dynamically determine the stable state threshold value. This means that when the production environment is noisy, the threshold value can be increased accordingly to avoid misinterpreting normal fluctuations as unstable conditions. Conversely, when the noise level is low, the threshold value can be lowered to increase the sensitivity of determining film stability. This dynamically determined stable state threshold value is then used to determine whether the acquired film fluctuation characteristic values ​​meet the preset stability conditions after the external process equipment has completed the change. When the fluctuation characteristic value is compared with this adaptive threshold and meets the conditions, the system can accurately determine that the film has returned to a stable state, thus ending the delay period and controlling the correction actuator to smoothly and promptly switch from the protective second control mode back to the first control mode, continuing closed-loop control to complete the overall lateral deviation compensation of the film. Precisely because of this mechanism of dynamically adjusting the judgment standard based on the actual baseline noise level, this solution ensures that the correction system can more accurately and robustly judge the film's recovery state after changes in the operating state of external process equipment. This avoids the frequent mode switching or switching lag caused by fixed threshold values, significantly improving the stability and control accuracy of the correction system, and ultimately ensuring product quality and production efficiency.

[0112] For example, when the cast film dynamic web correction control system is in the first control mode (i.e., when the web correction actuator is performing normal closed-loop control), the system can continuously collect real-time film position data from the edge sensor. For example, data can be collected every 10 milliseconds, and the most recent 1000 data points can be accumulated to form a data set within a sliding window. This data set represents the current baseline noise level. The system can then calculate a baseline fluctuation value based on this baseline noise level edge sensor position data. Specifically, the standard deviation of these 1000 data points can be calculated as the baseline fluctuation value. The standard deviation effectively reflects the dispersion of the data points, that is, the fluctuation amplitude of the film edge position. Next, based on the calculated baseline fluctuation value, the system can dynamically determine a stable state threshold value. For example, a predefined function can be used, such as stable state threshold value = K * baseline fluctuation value + C, where K and C are constants determined through experience or calibration experiments. Alternatively, the system can maintain a lookup table that stores recommended stable state threshold values ​​for different baseline fluctuation value ranges. The system then retrieves the corresponding threshold value from the lookup table based on the currently calculated baseline fluctuation value. Finally, when the external process equipment's operating status changes to "Complete," the system collects the film's fluctuation characteristic value and, based on the dynamically determined stability threshold, determines whether it meets the preset stability condition. For example, if the fluctuation characteristic value is less than or equal to the currently determined stability threshold, the film is considered to have reached a stable state. At this point, the delay period ends, and the correction actuator switches from the second control mode to the first control mode, resuming normal closed-loop correction operation.

[0113] It should be noted that the steps of determining the stable state threshold value based on the baseline fluctuation value include: performing a calibration operation on the preset film type, obtaining the baseline fluctuation reference value of the preset film type, and obtaining the recovery characteristic data of the preset film type after the external process equipment stops functioning; establishing a relationship set of the stable state threshold value based on the baseline fluctuation reference value and the recovery characteristic data; and determining the stable state threshold value based on the baseline fluctuation value and the relationship set.

[0114] The calibration operation here refers to obtaining the inherent characteristic data of a specific film type under different working conditions through experiments or tests under controlled conditions. It can be achieved by simulating production line operation in a laboratory environment, or by conducting small-batch trial production and collecting data on the actual production line. Its purpose is to provide a reference basis for the subsequent determination of the stable state threshold value.

[0115] The baseline fluctuation reference value here refers to the inherent fluctuation level of the film edge reflected by the position data collected by the edge sensor when the film is in a stable operating state and there is no interference from external process equipment. It can be expressed by calculating the standard deviation, root mean square value or peak-to-peak value of the edge sensor position data over a period of time. Its purpose is to quantify the inherent stability of different film types during normal operation.

[0116] The recovery characteristic data here refers to the dynamic change characteristics of the edge position of the film when it recovers from the disturbed state to the stable state after the external process equipment stops working. It can be expressed by recording the time required for the edge position of the film to recover to the stable range, the attenuation rate of the recovery curve or the maximum deviation value during the recovery process. Its purpose is to reflect the response and recovery ability of the film to external interference.

[0117] The relationship set of the stable state threshold value here refers to a set of corresponding relationships between baseline fluctuation reference values, recovery characteristic data and stable state threshold values. It can be implemented using a multidimensional lookup table, a mathematical model based on regression analysis, or a mapping rule obtained through training of a machine learning algorithm. Its purpose is to associate the inherent characteristics and recovery behavior of the film with appropriate stable state threshold values.

[0118] This embodiment of the present invention introduces a calibration operation for a preset film type to obtain its baseline fluctuation reference value and recovery characteristic data after external process equipment stops. Based on this data, a relationship set for the stable state threshold value is established. In actual operation, the stable state threshold value is determined based on the current baseline fluctuation value and the relationship set. Because different film types have different inherent fluctuation behaviors and recovery behaviors after being affected by external process equipment, relying solely on a single baseline fluctuation value to set the stable state threshold value is inaccurate. This solution obtains the film's baseline fluctuation reference value through calibration, which reflects the film's inherent fluctuation level in a normal stable state and provides a basis for threshold value setting. Simultaneously, recovery characteristic data is obtained, which characterizes the dynamic process by which the film's edge position returns to a stable state after external interference is eliminated. This is important for determining when it is safe to switch the corrective actuator from protective control mode back to closed-loop control mode. By combining the baseline fluctuation reference value and recovery characteristic data to establish a relationship set for the stable state threshold value, threshold value determination no longer relies on a single-dimensional consideration, but instead integrates both the film's static inherent characteristics and its dynamic recovery behavior. When the actual baseline fluctuation value is calculated, the system can use this relationship set, combined with the current film type and its recovery characteristics, to dynamically adjust a more accurate stable state threshold value. This more accurate stable state threshold value can more accurately judge whether the fluctuation characteristic value meets the preset stability conditions, thereby ensuring that the correction actuator ends the delay period and switches back to the first control mode only after the film is truly stable. This avoids the problem of premature switching causing malfunction of the correction system or late switching resulting in reduced production efficiency due to improper threshold value setting, allowing the correction system to operate stably and reliably when responding to changes in external process equipment, effectively avoiding unexpected stress or wrinkles in the film.

[0119] For example, here we can first select several commonly used film types, such as polypropylene (PP) film, polyester (PET) film and polyethylene (PE) film, and perform calibration operations on them. During the calibration process, you can simulate the scenario of the production line after the external process equipment (such as the cooling nozzle) stops working. For example, for PP film, after the cooling nozzle stops working, the edge sensor continuously collects the position data of the edge of the film to form a recovery process data sequence. From this sequence, the baseline fluctuation reference value of the film in a stable state can be calculated, for example, by calculating the standard deviation of the position data over a period of time. At the same time, the recovery process data sequence can be analyzed to determine the recovery characteristic data, for example, recording the time required for the edge position of the film to recover from the maximum deviation to its baseline fluctuation reference value range, or calculating the average slope of the recovery curve.

[0120] Based on this calibration data, a set of relationships between stable-state threshold values ​​can be established. For example, a multidimensional lookup table can be constructed, where the rows represent different film types, the columns represent different baseline fluctuation reference value ranges and recovery characteristic data (such as recovery time), and the cells in the table store the corresponding recommended stable-state threshold values. Alternatively, a regression model can be trained using historical calibration data. The model takes film type, baseline fluctuation reference value, and recovery characteristic data as input and outputs a predicted stable-state threshold value.

[0121] In the actual cast film production process, when the external process equipment stops functioning, the system will collect the edge sensor position data of the current film in real time and calculate the current baseline fluctuation value. The system will then identify the type of film currently being produced and query or calculate the relationship set through the model. For example, if the film currently being produced is PP film, and its baseline fluctuation value is within a specific range, and its recovery characteristics are judged to be of the "quick recovery" type based on historical data or real-time analysis, the system can search or calculate the stable state threshold value that matches these conditions from the relationship set. This dynamically determined threshold value will be used to determine whether the film has truly recovered and stabilized, thereby determining when the correction actuator switches from the protective control mode back to the closed-loop control mode.

[0122] It should be noted that the relationship set for establishing a stable state threshold value based on the baseline fluctuation reference value and the recovery characteristic data in the embodiment of the present invention includes: when performing a calibration operation on a preset film type, obtaining a set of calibration data corresponding to multiple preset process parameter points, each calibration data in a set of calibration data includes the baseline fluctuation reference value and recovery characteristic data obtained under the preset process parameter point; determining the target stable state threshold value associated with the preset process parameter point corresponding to each calibration data, the target stable state threshold is used to establish a multi-point correspondence between the preset process parameter point and the target stable state threshold value, and the relationship set includes the multi-point correspondence; obtaining the current process parameter value; determining the stable state threshold value based on the current process parameter value and the multi-point correspondence.

[0123] The multi-point correspondence here refers to a mapping mechanism in which a certain association exists between a series of discrete input points (such as process parameter points) and a series of corresponding output values ​​(such as target stable state threshold values). This relationship can be established and represented specifically through a lookup table, an interpolation algorithm (such as linear interpolation, cubic spline interpolation) or a regression model (such as polynomial regression, nonlinear regression).

[0124] The method of the present invention improves the adaptability and accuracy of deviation correction control by incorporating process parameters into the determination of stable-state thresholds. Specifically, when calibrating a predetermined film type, the system acquires a set of calibration data corresponding to multiple preset process parameter points. This data set includes baseline fluctuation reference values ​​and recovery characteristic data for the film under different process parameters. In this way, the system can capture the dynamic behavior characteristics of the film under various production conditions. Subsequently, for each calibration data set, the system determines a target stable-state threshold associated with its corresponding process parameter point and uses these points to establish a multi-point correspondence between the process parameter point and the target stable-state threshold. This multi-point correspondence constitutes a set of stable-state threshold relationships. Rather than being a fixed value or a judgment based on a single factor, it provides a basis for dynamic adjustment based on actual production conditions. In actual operation, the system acquires the current process parameter values ​​in real time and, based on these parameter values ​​and the established multi-point correspondence, accurately determines the appropriate stable-state threshold for the current operating conditions. This method of dynamically determining the stable state threshold value, combined with the method of establishing a relationship set and determining the threshold value based on the baseline fluctuation value and recovery characteristic data in the previous solution, enables the system to accurately and reliably determine whether the fluctuation characteristic value meets the preset stability conditions. In particular, after the external process equipment (such as the cooling nozzle) stops functioning, the film needs a recovery process to reach a stable state. Through the precise stable state threshold value, the system can avoid switching back to the closed-loop control mode too early when the film is not yet completely stable, thereby avoiding excessive or improper correction caused by misjudgment of the stable state, and preventing the film from generating internal stress, wrinkles and other quality problems. This improvement in the accuracy of stable state judgment ensures that the correction actuator can switch back to the closed-loop control mode from the protective control state at an optimized time after the delay period ends, thereby improving the efficiency and reliability of the correction control while ensuring product quality.

[0125] For example, on a cast film production line, dynamic deviation correction control is required for a specific polyester film. The main process parameters affecting film stability may include the air pressure of the cooling nozzle and the film pulling speed. In order to establish a relationship set of stable state threshold values, a calibration operation is first performed. Specifically, during the production line commissioning phase or in a special calibration mode, the system selects multiple preset process parameter points for testing. For example, the air pressure of the cooling nozzle is set to 0.5 MPa, 0.8 MPa, and 1.0 MPa, and the pulling speed is set to 50 m / min, 60 m / min, and 70 m / min, thereby forming nine different process parameter combination points. For each process parameter point, the system obtains a set of calibration data, which includes the baseline fluctuation reference value (for example, the standard deviation of the edge sensor position data) when the film is running stably at this specific air pressure and pulling speed, as well as the recovery characteristic data (for example, the decay time or decay coefficient of the film edge oscillation) when the film returns to a stable state after simulating the cessation of external process equipment (such as the cooling nozzle).

[0126] Subsequently, through offline analysis or expert system evaluation of these nine calibration data sets, the target stable state threshold values ​​associated with the process parameter points corresponding to each calibration data set are determined. These target stable state threshold values ​​are the thresholds used to determine whether the film has reached a stable state under specific process parameter combinations. For example, at low pressure and low speed, the film is more likely to stabilize, so the corresponding target threshold value can be set smaller; at high pressure and high speed, the film can fluctuate more, so the target threshold value can be appropriately relaxed.

[0127] Next, a multi-point correspondence is established using these process parameter points and their corresponding target stable state thresholds. This relationship can be expressed as a multidimensional lookup table, taking pressure and speed as input and outputting the corresponding target stable state threshold. Alternatively, a polynomial regression model can be used to fit a mathematical function, such as ˋThreshold = f(pressure, speed)ˋ, allowing the system to calculate the corresponding threshold value based on any pressure and speed value.

[0128] During actual production operations, the system acquires current process parameter values ​​in real time, such as the current cooling nozzle air pressure and traction speed, via sensors. Finally, the system inputs these current process parameter values ​​into a previously established multi-point correspondence (whether a lookup table or a mathematical model), dynamically determining the appropriate stable state threshold for the current operating conditions. This dynamically determined stable state threshold is used to determine whether the film fluctuation characteristic value meets the preset stability conditions, thereby controlling the correction actuator to switch from the protective control state back to the closed-loop control mode.

[0129] The steps of obtaining recovery characteristic data of a preset film type after the external process equipment stops functioning in an embodiment of the present invention include: after the external process equipment stops functioning, collecting a series of position data output by the edge sensor, and forming a recovery process data sequence with the series of position data; determining characteristic parameters of the dynamic recovery process based on the recovery process data sequence; and using the characteristic parameters as recovery characteristic data.

[0130] The characteristic parameters of the data sequence's dynamic process are key values ​​that quantify the dynamic behavior of the film's edge position over time after the external process equipment ceases to function. These parameters can reflect properties of the film material, such as elasticity, damping, inertia, and attenuation of external disturbances. For example, they may include the film's edge position's recovery speed, oscillation frequency, attenuation coefficient, stabilization time, or maximum offset. The goal is to refine the complex, continuous recovery process data sequence into concise, representative values ​​to facilitate subsequent analysis, modeling, and application, thereby more accurately characterizing the film's recovery characteristics.

[0131] The solution of this application systematically acquires data on the film's recovery characteristics after external process equipment ceases operation, providing a more reliable basis for switching the correction control system from a protective control mode back to a closed-loop control mode. Specifically, after the external process equipment ceases operation, the film edge undergoes a dynamic process of recovery from a disturbed state to a stable state. To accurately capture this process, the system continuously collects a series of position data output by the edge sensor, which together form a recovery process data sequence. Because film recovery is not instantaneous but rather a time-dependent dynamic change, forming a complete data sequence comprehensively records the trajectory of the film's position over time, avoiding the limitations of relying solely on a single or small number of data points. Based on this recovery process data sequence, the system extracts and determines characteristic parameters of the data sequence's dynamic process. These characteristic parameters are refined, key values ​​that reflect the essential properties of the film's recovery, such as the speed of recovery, the frequency of oscillation, and the degree of attenuation. Extracting these characteristic parameters is necessary because the original position data sequence may contain a large amount of redundant information or noise, and using them directly would reduce analysis efficiency and accuracy. By converting the dynamic process into a set of refined characteristic parameters, the film's recovery characteristics can be described more concisely and effectively. These parameters reflect the inherent properties of the film material, such as elasticity or damping. Ultimately, these determined characteristic parameters are used as recovery characteristic data. This recovery characteristic data comprehensively and accurately characterizes the actual recovery behavior of a given film type after the external process equipment ceases operation. In some previous solutions, a relationship set of stable state threshold values ​​was established based on baseline fluctuation reference values ​​and recovery characteristic data to determine when the corrective actuator switches from the second control mode to the first control mode. The more accurate recovery characteristic data obtained through this solution allows the established stable state threshold value relationship set to more accurately reflect the film's actual recovery state, thereby only performing mode switching when the film is truly stable. This avoids premature or late switching due to inaccurate recovery characteristic data, effectively improving the accuracy and stability of corrective control, ensuring a smooth transition of the film during recovery, and avoiding unnecessary corrective actions or film damage caused by misjudgment.

[0132] For example, when external process equipment, such as a forced cooling nozzle, ceases operation, the system immediately activates an edge sensor to continuously collect position data. This edge sensor can be a high-precision photoelectric sensor or a CCD linear array camera, with a sampling rate of hundreds of times per second to capture rapid, dynamic changes in the film edge. This continuously collected position data, for example, thousands of data points collected over a period of seconds or tens of seconds, is chronologically arranged to form a recovery process data sequence. Furthermore, based on this recovery process data sequence, signal processing and data analysis methods can be used to determine characteristic parameters of the data sequence's dynamic process. For example, curve fitting, such as an exponential decay curve or a damped oscillation curve, can be performed on the recovery process data sequence to extract parameters such as the decay constant, oscillation period, initial offset, and final stable value. Alternatively, the data sequence's volatility and recovery speed can be quantified by calculating its root mean square value, standard deviation, peak-to-peak value, or average rate of change over a specific time period. For example, the time required for the film edge position to recover from its maximum offset to 90% of its stable value can be calculated, or the amplitude of the film edge position oscillation during the recovery process can be calculated. These calculated values, such as attenuation coefficient and recovery time, serve as the recovery characteristic data for the preset film type. These data can be stored in the system's memory or database for subsequent use in establishing a relationship set for stable state threshold values.

[0133] Accordingly, Figure 3 The following is a schematic structural diagram of a cast film dynamic deviation correction control system according to an embodiment of the present invention, which is used to implement a cast film dynamic deviation correction control method. The system includes:

[0134] Status acquisition module, used to collect working status signals of external process equipment that affect the correction system;

[0135] A status judgment module is used to judge whether the working status of the external process equipment has changed based on the working status signal;

[0136] A first control module is configured to set the deviation correction actuator to a first control mode when determining that the working state is an inactive state, so that the deviation correction actuator performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film;

[0137] a second control module configured to switch the correction actuator from the first control mode to the second control mode when determining that the working state has changed to the start-up state, wherein the correction actuator terminates the closed-loop control of the correction actuator based on the second control mode and maintains the correction actuator in a protective control state, wherein the protective control state is a process in which the correction actuator waits for the external process equipment to complete the changed working state;

[0138] The third control module is used to switch the correction actuator from the second control mode to the first control mode when it is determined that the working state changes to the completion state. The correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film.

[0139] Among them, the state acquisition module refers to the hardware or software unit responsible for obtaining the operating status information of the external process equipment, which can be a sensor, data interface or communication protocol, and its purpose is to provide the system with real-time and accurate external environment data; the state judgment module refers to the logic unit that analyzes and processes the collected working status signals of the external process equipment to determine its current state or whether the state has changed, which can be identified by comparing the current signal with the preset threshold or historical data. Its purpose is to provide a decision basis for subsequent control mode switching; the first control module refers to the management of the correction execution mechanism when the external process equipment is in a stable or non-interference state. The logic unit for conventional closed-loop control can be, specifically, a PID controller or a fuzzy logic controller to achieve real-time compensation for the lateral deviation of the film, with the purpose of ensuring the stable operation of the film under normal production conditions; the second control module refers to the logic unit responsible for switching the correction actuator from the conventional control mode to the protective control state when the external process equipment is started or changes occur, specifically, it can be a logic unit that immediately issues an instruction after receiving a state change signal to suspend or limit the action of the correction actuator, with the purpose of avoiding erroneous correction or excessive correction caused by external interference; the third control module refers to the logic unit responsible for switching the correction actuator from the conventional control mode to the protective control state after the external process equipment completes its change process and returns to stability. The logic unit of the actuator switching from the protective control state back to the conventional closed-loop control mode can be specifically triggered by monitoring the completion signal of the external device or the stable signal of the film state, with the purpose of enabling the correction system to resume normal operation in time and continue to accurately compensate the film; the first control mode refers to the working state of the correction actuator under normal production conditions, which is precisely adjusted by real-time feedback, specifically by continuously monitoring the edge position of the film and calculating the deviation, and then driving the actuator to make corresponding corrections, with the purpose of achieving continuous and precise compensation for the overall lateral deviation of the film; the second control mode refers to the correction actuator in the external process equipment During startup or change, the active correction action is suspended or restricted to avoid unnecessary interference or damage to the working state. Specifically, it can be done by freezing the current actuator position or placing it in a safe position. The purpose is to protect the correction system and the film from external transient interference; the protective control state refers to a non-active correction but standby state maintained by the correction actuator in the second control mode. Specifically, it can mean that the actuator maintains its current position or moves to a preset safe position while waiting for the external process equipment to complete its change process. Its purpose is to prevent the correction system from making an erroneous response during external interference and to prepare for the system to resume normal operation.

[0140] The system involved in the embodiment of the present invention decomposes the complex control logic into independent units of state acquisition, state judgment and multi-mode control through a modular design, so that the dynamic correction strategy in the method can be stably and reliably deployed and operated in an actual production environment. Specifically, the system can intelligently switch between conventional closed-loop control mode and protective control mode according to the working status of external process equipment, thereby avoiding miscorrection or excessive correction caused by transient interference during the startup or change of external equipment, and effectively preventing wrinkles or stress defects in the film. This significantly improves the adaptability and robustness of the correction system, ensuring the continuity of the cast film production process and the stability of product quality.

[0141] The above description is merely an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, various modifications and variations of the present application are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A cast film dynamic deviation correction control method, characterized in that: include: Collect working status signals of external process equipment that affect the correction system; determining whether the working state of the external process equipment has changed based on the working state signal; If it is determined that the working state is the inactive state, the deflection correction actuator is set in the first control mode, and the deflection correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film; If it is determined that the working state has changed to the start-up state, the correction execution mechanism is switched from the first control mode to the second control mode. The correction execution mechanism terminates the closed-loop control of the correction execution mechanism based on the second control mode and maintains the correction execution mechanism in a protective control state. The protective control state is a process in which the correction execution mechanism waits for the external process equipment to complete the changed working state. If it is determined that the working state has changed to the completion state, the correction execution mechanism is switched from the second control mode to the first control mode, and the correction execution mechanism performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film.

2. A cast film dynamic deviation correction control method according to claim 1, characterized in that: The correction actuator performs closed-loop control in the first control mode to complete the overall lateral deviation compensation of the film, including: Collect actual position data of the film based on edge sensors; Based on the actual position data, a pivotable guide roller is driven to apply a lateral force component to the film.

3. The cast film dynamic deviation correction control method according to claim 1, characterized in that: Switching the deviation-correcting actuator from the second control mode to the first control mode includes: When detecting that the working state changes to a completion state, extracting the delay period set for the deviation correction execution mechanism; The deviation correction execution mechanism is controlled to switch from the second control mode to the first control mode based on the delay period.

4. A cast film dynamic deviation correction control method according to claim 3, characterized in that: The controlling the deviation correction actuator to switch from the second control mode to the first control mode based on the delay period includes: Collect a set of location data based on edge sensors; Calculating a fluctuation characteristic value of the degree of dispersion of the set of position data; Determining whether the fluctuation characteristic value meets a preset stability condition of a stable state threshold value; When the fluctuation characteristic value meets the preset stability condition, the delay period is ended, and the deviation correction execution mechanism is controlled to switch from the second control mode to the first control mode.

5. A cast film dynamic deviation correction control method according to claim 4, characterized in that: Calculating the fluctuation characteristic value of the discrete degree of the set of position data includes: performing sorting processing on the set of position data; Eliminate a preset number of extreme value data from a group of position data that has completed sorting processing to form a core data group; The fluctuation characteristic value of the discrete degree of the set of position data is calculated based on the core data set.

6. A cast film dynamic deviation correction control method according to claim 4, characterized in that: The determining whether the fluctuation characteristic value satisfies a preset stability condition of a stable state threshold value includes: In the first control mode, obtaining a set of edge sensor position data representing a baseline noise level; calculating a baseline fluctuation value based on edge sensor position data of the baseline noise level; determining the steady state threshold value based on the baseline fluctuation value; It is determined whether the fluctuation characteristic value satisfies the preset stability condition based on the stable state threshold value.

7. A cast film dynamic deviation correction control method according to claim 6, characterized in that: Determining the stable state threshold value based on the baseline fluctuation value includes: Performing a calibration operation on a preset film type to obtain a baseline fluctuation reference value of the preset film type and obtaining recovery characteristic data of the preset film type after the external process equipment stops functioning; establishing a relationship set of the stable state threshold value based on the baseline fluctuation reference value and the restoration characteristic data; The stable state threshold value is determined based on the baseline fluctuation value and the relationship set.

8. A cast film dynamic deviation correction control method according to claim 7, characterized in that: The relationship set for establishing the stable state threshold value based on the baseline fluctuation reference value and the restoration characteristic data includes: When performing a calibration operation on the preset film type, a set of calibration data corresponding to a plurality of preset process parameter points is obtained, wherein each calibration data in the set of calibration data includes a baseline fluctuation reference value and recovery characteristic data obtained at the preset process parameter point; Determining a target stable state threshold value associated with a preset process parameter point corresponding to each calibration data, wherein the target stable state threshold value is used to establish a multi-point correspondence relationship between the preset process parameter point and the target stable state threshold value, and the relationship set includes the multi-point correspondence relationship; Get the current process parameter values; The stable state threshold value is determined based on the current process parameter value and the multi-point correspondence relationship.

9. A cast film dynamic deviation correction control method according to claim 7, characterized in that: The obtaining of the recovery characteristic data of the preset film type after the external process equipment stops functioning comprises: After the external process equipment stops functioning, collecting a series of position data output by the edge sensor, and forming a recovery process data sequence with the series of position data; Determining characteristic parameters of a dynamic recovery process based on the recovery process data sequence; The characteristic parameters are used as the restoration characteristic data.

10. A cast film dynamic deviation correction control system, used to implement the cast film dynamic deviation correction control method according to any one of claims 1 to 9, characterized in that: The system includes: Status acquisition module, used to collect working status signals of external process equipment that affect the correction system; a state judgment module, configured to judge whether the working state of the external process equipment has changed based on the working state signal; a first control module, configured to set the deflection correction actuator to a first control mode when determining that the working state is an inactive state, so that the deflection correction actuator performs closed-loop control in the first control mode to compensate for the overall lateral deviation of the film; a second control module, configured to switch the correction actuator from the first control mode to the second control mode when it is determined that the working state has changed to the start state, wherein the correction actuator terminates the closed-loop control of the correction actuator based on the second control mode and maintains the correction actuator in a protective control state, wherein the protective control state is a process in which the correction actuator waits for the external process equipment to complete the changed working state; The third control module is used to switch the correction actuator from the second control mode to the first control mode when it is determined that the working state changes to the completion state. The correction actuator performs closed-loop control in the first control mode to complete the overall lateral offset compensation of the film.

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