Double closed loop control method and system for suppressing high frequency transient nonlinear tension disturbance

Abstract

The application belongs to the technical field of production line control, and discloses a double closed-loop control method and system for suppressing high-frequency transient nonlinear tension disturbance. The tension deviation and speed compensation value are determined according to the tension change of the flexible base material. The servo motor adjustment instruction is determined according to the linear speed deviation, tension disturbance and thermal disturbance. The tension of the flexible base material is adjusted according to the tension deviation. The servo motor speed of the winding end or the unwinding end is adjusted according to the servo motor adjustment instruction. The layered control of the tension outer ring and the speed inner ring is constructed, the bidirectional adjustment of the tension and the servo motor speed is realized, the double closed-loop control is completed, and the stability of the coiled material preparation process is greatly enhanced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of production line control, and relates to a double closed-loop control method and system for suppressing high-frequency transient nonlinear tension disturbance of a web production line. BACKGROUND

[0002] The flexible substrate continuous transmission system is a core link in the fields of film manufacturing, coating and surface treatment. In modern high-precision manufacturing, keeping the tension of the flexible substrate constant during transmission is the key to ensuring that the material does not yield and deforms and to ensuring the processing quality. The essence of tension control is a complex dynamic problem involving mechanical transmission nonlinearity, material elasticity variability and multi-axis coupling.

[0003] However, surface functionalization processes such as plasma deposition, precision coating, micro-nano etching and other technologies often involve special working conditions, which can easily induce high-frequency, transient and nonlinear tension disturbance of the flexible substrate. The traditional single-loop PID control architecture forcibly couples the inherent inertia of the mechanical actuator, transmission friction and process tension requirements in the same control loop. In the face of such high-frequency transient impact, the physical lag of the mechanical transmission can cause serious integral saturation and 90-degree phase lag, causing large tension overshoot and long-term system oscillation, thereby completely destroying the stability of the reaction.

[0004] At present, various solutions have been proposed in the industry for web tension control, but none of them can effectively overcome the above-mentioned high-frequency transient disturbance problem.

[0005] Conventional tension PID control usually directly takes the tension deviation as the PID input, and then converts the PID output into motor speed, current or torque command in proportion or normalization. This method can achieve tension regulation under low-frequency slow-changing conditions, but under short-time disturbance such as high-temperature thermal shrinkage, air flow impact, coating liquid impact, etc., if there is a lack of mechanical buffer and clear dimensional mapping, it is easy to have response lag, large peak deviation or unclear formula expression.

[0006] Patent CN116281334B discloses a web tension control system and control method, which integrates tension PID deviation, acceleration / deceleration compensation value and PID proportional coefficient (P value) dynamically adjusted according to the roll diameter ratio control system. The system attempts to stabilize the tension by superimposing multiple feedforward signals. However, this method is mainly aimed at slow-changing disturbances such as roll diameter changes, machine start / stop, etc. This single-loop structure with multiple signals directly superimposed at the mathematical level lacks physical isolation of the underlying mechanical nonlinearity. When encountering unpredictable transient high-frequency thermal shock, it is impossible to respond by modifying the proportional coefficient through table lookup, and the system will still experience severe oscillation.

[0007] Patent CN111891811B discloses a kind of system and control method of tension PID hybrid control of roll production line, by setting highest speed limit signal, forcedly scaled PID output speed adjustment signal, to prevent overshoot oscillation when fast response control appears.But, this method uses the compromise strategy of "sacrifice dynamic response speed to obtain no overshoot".In high-temperature continuous deposition process, the slowing down of response speed means that the film jitter state caused by thermal shrinkage will exist, which is a fatal defect for precision coating process requiring absolute flat physical boundary.

[0008] Patent CN121708265A discloses a kind of positioning transfer paper shrinkage deformation monitoring and fixed-length stretching compensation method, utilizes line array vision sensor to synchronously collect film image, identifies anchor point by improving Hough transform, calculates physical spacing deviation to dynamically adjust line speed difference and tension method.But, there is huge calculation time consumption from visual image acquisition, algorithm recognition to final output motor instruction, which belongs to typical "large hysteresis visual feedback loop".This method is only suitable for compensating extremely slow cumulative deformation, and cannot capture and suppress high-frequency transient physical jitter of hundred milliseconds.

[0009] In summary, the existing technology generally has the defects of strong coupling of control level, mechanical inertia dragging response speed, or sacrificing response speed for stability, which cannot meet the strict process requirements of "requiring fast response and no overshoot oscillation" under high-frequency transient nonlinear tension disturbance. SUMMARY

[0010] The purpose of the present application is to provide a kind of double closed loop control method and system for inhibiting high-frequency transient nonlinear tension disturbance, construct tension outer ring and speed inner ring hierarchical control;Tension outer ring converts tension deviation into speed given correction, finally by speed inner ring control servo motor to track the speed given.

[0011] To achieve the above purpose, the present application adopts the following technical solutions to realize.

[0012] The present application provides a kind of double closed loop control method for inhibiting high-frequency transient nonlinear tension disturbance, suitable for flexible substrate winding and unwinding process, which includes the following steps:

[0013] S1, tension outer ring control: according to the tension change of flexible substrate to determine tension deviation and speed compensation value;

[0014] This step includes the following sub-steps:

[0015] S11, according to the actual tension of flexible substrate and preset target tension, determine the tension deviation;

[0016] S12, obtaining a line speed compensation value through a tension ring PI controller according to the tension deviation;

[0017] S2, speed inner loop control: determining a servo motor adjustment instruction according to a line speed deviation, a tension disturbance and a thermal disturbance;

[0018] This step includes the following sub-steps:

[0019] S21, determining a line speed deviation according to an actual line speed and a target line speed, and determining a servo motor pre-adjustment instruction through a speed ring PID controller according to the line speed deviation;

[0020] S22, constructing a tension damping compensation item according to a tension change rate of the flexible base material;

[0021] S23, constructing a thermal disturbance feedforward compensation item according to a thermal disturbance change rate caused by thermal shrinkage of the flexible base material;

[0022] S24, obtaining a servo motor adjustment instruction by weighted fusion of the servo motor pre-adjustment instruction, the tension damping compensation item and the thermal disturbance feedforward compensation item;

[0023] S3, adjusting the tension on the flexible base material according to the tension deviation determined in step S1;

[0024] S4, adjusting the servo motor speed of the winding end or the unwinding end according to the servo motor adjustment instruction determined in step S2.

[0025] The above-mentioned double closed loop control method for suppressing high frequency transient nonlinear tension disturbance can adjust the servo motor speed of the winding end or the unwinding end through steps S1-S4. For the winding end and the unwinding end, corresponding tension outer loop and speed inner loop are respectively set. In the preferred implementation, in view of the high frequency disturbance, this method is more suitable for adjusting the servo motor speed of the winding end, and the line speed can use the basic line speed set at the initial moment. In this application, the line speed refers to the line speed of the winding roller or the unwinding roller surface.

[0026] Taking the winding end as an example, the actual line speed is expressed as:

[0027] ;

[0028] ;

[0029] ;

[0030] Wherein, R(k) represents the current radius of the winding end material in the kth sampling period; ω(k) represents the motor angular velocity in the kth sampling period, which can be obtained through an encoder; n(k) represents the motor speed in the kth sampling period; R0 represents the radius of the winding end roller; represents the accumulated length of the substrate that has been wound up in the kth sampling period; represents the actual linear speed of the flexible substrate at the winding end in the ith sampling period, represents the actual linear speed of the flexible substrate at the winding end at the initial moment; h represents the thickness of the substrate.

[0031] The purpose of the above step S1 is to convert the tension deviation into a linear speed given correction amount through tension inner loop control. The actual tension at the unwinding end or the winding end of the flexible substrate is measured, and compared with the preset target tension to obtain the current tension deviation; and the proportional-integral of the tension loop PI controller is used to calculate the linear speed compensation value.

[0032] In the above step S11, a floating roller for adjusting or buffering tension is arranged near the unwinding end or / and the winding end of the flexible substrate. The floating roller is supported by a gas cylinder, which absorbs sudden changes in tension by means of gas buffering, while adjusting the internal gas to maintain a tensioned state. A pressure sensor is arranged in the gas circuit of the gas cylinder, which is used to collect the gas pressure. After conversion, the actual tension suffered by the flexible substrate can be obtained.

[0033] ;

[0034] ;

[0035] wherein, represents the actual tension in the kth sampling period; represents the thrust of the gas cylinder; represents the gas pressure detected by the pressure sensor in the kth sampling period; represents the effective pressure receiving area of the piston of the gas cylinder; represents the equivalent conversion coefficient from pressure to tension, which is obtained by calibration; is the self-weight of the floating roller.

[0036] In the preferred implementation, floating rollers are arranged near the unwinding end and the winding end of the flexible substrate, and a pressure sensor is arranged in the gas cylinder near the winding end to obtain the actual tension of the flexible substrate. In order to suppress measurement noise, the obtained actual tension can be subjected to filtering processing.

[0037] ;

[0038] wherein, represents the actual tension after filtering processing in the kth sampling period; represents the filtering coefficient, = exp(- ), represents the tension measurement filtering time constant, represents the sampling period; actual tension of the kth sampling period.

[0039] The normalized result of the difference between the actual tension of the flexible substrate and the preset target tension is taken as the tension deviation, denoted as .

[0040] In the above step S12, the line speed compensation value is obtained through the tension loop PI controller according to the tension deviation, which is expressed as:

[0041] ;

[0042] wherein, denotes the speed calibration scale, denotes the force proportional coefficient, denotes the force integral coefficient, denotes the tension deviation of the kth sampling period, denotes the tension deviation of the ith sampling period, denotes the sampling period, i.e. the time interval between adjacent tension sampling and control calculation.

[0043] Further, the is limited to obtain :

[0044] ;

[0045] wherein, denotes the limiting function, , respectively denote the lower limit and the upper limit of the speed compensation value.

[0046] The final line speed compensation value is output to the speed inner loop and does not directly act on the servo motor speed regulation.

[0047] The purpose of the above step S2 is to obtain the speed inner loop PID controller output based on the line speed deviation through the speed inner loop control, and to compensate the output by using the tension disturbance and the thermal disturbance to obtain the servo motor adjustment instruction.

[0048] In the above step S21, the basic line speed is given, and the weighted fusion result of the basic line speed and the line speed compensation value is taken as the target line speed, which is expressed as:

[0049] ;

[0050] wherein, denotes the target line speed, denotes the basic line speed, denotes the speed compensation direction coefficient.

[0051] The difference between the actual linear velocity and the target linear velocity is taken as the linear velocity deviation, and is expressed as:

[0052] ;

[0053] in, Indicates the actual linear velocity;

[0054] Based on the linear velocity deviation, the output obtained through the speed loop PID controller is the servo motor pre-adjustment command:

[0055] ;

[0056] in, Indicates the speed proportionality coefficient. Represents the velocity integral coefficient. Represents the velocity differential coefficient. This represents the velocity integral term.

[0057] In step S22 above, the discrete tension change rate is defined as the disturbance prediction quantity:

[0058] ;

[0059] in, , representing the tension change rate filter coefficient, 0 < <1; This represents the rate of change of tension during the k-th sampling period; This represents the time constant for the tension change rate filtering. During initialization, D can be set... F (0)=0.

[0060] Construct a tension damping compensation term based on the rate of change of tension:

[0061] ;

[0062] in, The damping coefficient represents the rate of change of tension. This indicates the tension normalization scale. When a rapid increase or decrease in tension is detected, the motor drive is corrected in advance, rather than waiting for speed errors to accumulate before adjustment.

[0063] In step S23 above, a thermal disturbance feedforward compensation term is introduced to address the thermal contraction disturbance caused by temperature shock:

[0064] ;

[0065] ;

[0066] in, This represents the thermal disturbance compensation coefficient. This represents the rate of change of thermal disturbance in the k-th sampling period; This represents the actual temperature measured in the k-th sampling period. Specifically, it can measure the actual temperature of the flexible substrate at the winding or unwinding end. This parameter corrects the motor output in advance during periods of rapid temperature change, reducing sudden tension changes caused by high-temperature shocks.

[0067] In step S24, tension damping compensation and thermal disturbance feedforward supplementation terms are added to the servo motor pre-adjustment command to obtain the final servo motor adjustment command:

[0068] ;

[0069] in, and These represent the direction coefficients for compensation of the rate of change of tension and thermal disturbance, respectively.

[0070] Furthermore, regarding Obtain by limiting the amplitude This ensures that the output signal meets the driver's allowable range.

[0071] ;

[0072] in, , These represent the lower and upper limits of the servo motor adjustment command, respectively. The servo motor adjustment command is limited and represents the equivalent acceleration in this invention.

[0073] Furthermore, the integral term After antisaturation correction, it becomes:

[0074] ;

[0075] in, Indicates the coefficient against integral saturation; , These are the actual outputs before and after the amplitude limiting at time k-1, respectively.

[0076] In step S3 above, the present invention mainly adjusts the tension on the flexible substrate by adjusting the floating roller based on the tension deviation; specifically, the air pressure of the cylinder supporting the floating roller is adjusted, thereby changing the supporting and buffering effect of the floating roller on the flexible substrate, thereby reducing transient tension fluctuations and ensuring the stability of the roll material conveying.

[0077] In step S4 above, the servo motor adjustment command is the equivalent linear acceleration. Dividing it by the winding diameter at the take-up or unwinding end gives the servo motor angular acceleration, which in turn determines the change in servo motor speed, thereby adjusting the servo motor speed.

[0078] The present invention also provides a dual-closed-loop control system for suppressing high-frequency transient nonlinear tension disturbances, used to implement the above-mentioned dual-closed-loop method for suppressing high-frequency transient nonlinear tension disturbances, comprising:

[0079] Tension outer ring control unit: used to determine tension deviation and linear velocity compensation values ​​based on the tension changes experienced by the flexible substrate; the tension outer ring control unit includes:

[0080] The tension deviation calculation module is used to determine the tension deviation based on the actual tension of the flexible substrate and the preset target tension.

[0081] The linear velocity compensation generation module is used to obtain the linear velocity compensation value based on the tension deviation through the tension loop PI controller;

[0082] Speed ​​inner loop control unit: used to determine servo motor adjustment commands based on linear speed deviation, tension disturbance, and thermal disturbance; this speed inner loop control unit includes:

[0083] The servo motor pre-adjustment command generation module is used to determine the linear speed deviation based on the actual linear speed and the target linear speed; and based on the linear speed deviation, it determines the servo motor pre-adjustment command through the speed loop PID controller.

[0084] The tension damping compensation term construction module is used to construct tension damping compensation terms based on the tension change rate of the flexible substrate.

[0085] A thermal disturbance feedforward compensation term construction module is used to construct thermal disturbance feedforward compensation terms based on the rate of change of thermal disturbance caused by thermal shrinkage of flexible substrates.

[0086] The servo motor adjustment command generation module is used to obtain the servo motor adjustment command by weighted fusion of the servo motor pre-adjustment command, tension damping compensation term and thermal disturbance feedforward supplement term.

[0087] The tension adjustment unit is used to adjust the tension on the flexible substrate based on the tension deviation.

[0088] The servo motor adjustment unit is used to adjust the speed of the servo motor at the take-up end or the unwinding end according to the servo motor adjustment command.

[0089] The above modules and units perform operations according to steps S1-S4 given in the previous dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances.

[0090] Compared with existing technologies, the dual closed-loop control method and system for suppressing high-frequency transient nonlinear tension disturbances provided by this invention have the following superior effects:

[0091] (1) The present invention constructs a layered control of tension outer loop and speed inner loop. The tension outer loop generates linear speed compensation based on tension deviation and transmits it to the speed inner loop. Tension disturbance and thermal disturbance are introduced in the speed inner loop to generate servo motor adjustment command, thereby realizing bidirectional adjustment of tension and servo motor speed, thus completing dual closed-loop control and greatly enhancing the stability of the roll material preparation process.

[0092] (2) This dual closed-loop control mode greatly improves the response speed, avoids oscillation and hysteresis, and controls force and speed separately, thereby improving the control accuracy.

[0093] (3) When the roll material is subjected to high-frequency disturbance, the present invention can quickly complete speed compensation, control the tension fluctuation within a very small range, greatly reduce the breakage rate, ensure the stability of the roll material transmission, and thus ensure the large-scale uniformity of the flexible substrate surface.

[0094] (4) This invention uses high-temperature thermal shrinkage as a typical form of high-frequency disturbance for explanation, but the same control framework can also be used for other transient tension disturbances such as airflow impact, coating liquid impact, and roller surface runout. Attached Figure Description

[0095] Figure 1 A schematic diagram illustrating the principle of unwinding and rewinding of flexible substrates;

[0096] Figure 2 A schematic diagram of the dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances provided in Example 1;

[0097] Figure 3 A schematic diagram illustrating the principle of the dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances provided in Example 1;

[0098] Figure 4 The simulation parameters of the three sets of PID are shown in the PID regulation process without high-frequency disturbances; curves 1-3 represent individual PID control, speed-tension series PID control and dual closed-loop PID control, respectively.

[0099] Figure 5 This is the PID control process under high-frequency disturbances; curves 1-3 represent individual PID control, speed-tension series PID control, and dual closed-loop PID control, respectively.

[0100] Figure 6 This represents the tension deviation and recovery under high-frequency disturbances; curves 1-3 represent individual PID control, speed-tension series PID control, and dual closed-loop PID control, respectively. Detailed Implementation

[0101] The technical solutions of various embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0102] Example 1

[0103] This embodiment provides a dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances, used to control the tension of flexible substrates during winding and unwinding processes.

[0104] The winding and unwinding process of flexible substrates is as follows Figure 1 As shown, the flexible substrate at the unwinding end passes through tension rollers and floating rollers into a working platform (such as a plasma deposition equipment, coating equipment, etching equipment, etc.) for surface processing of the flexible substrate. The flexible substrate exiting the working platform then passes through floating rollers and tension rollers again before being wound up at the rewinding end. Transition rollers are installed at both ends of the floating rollers. The two ends of the floating rollers are connected to the piston rods of a cylinder and are supported by the cylinders. The floating rollers can move accordingly with the piston rods. The cylinders absorb sudden tension changes using gas buffers.

[0105] In this embodiment, tension measurement at the winding end is performed, and dual closed-loop regulation is applied to the tension of the flexible substrate and the speed of the servo motor. A pressure sensor is installed inside the floating roller support cylinder on the winding side. The pressure sensor detects the pressure inside the cylinder in real time, and the actual tension on the flexible substrate is calculated from the pressure.

[0106] ;

[0107] ;

[0108] This represents the actual tension calculated during the k-th sampling period; This indicates the thrust of the cylinder; This represents the air pressure detected by the pressure sensor during the kth sampling period; This indicates the effective pressure-bearing area of ​​the cylinder piston; The equivalent conversion factor from pressure to tension is obtained through calibration; This represents the weight of the floating roller. Taking the direction of the cylinder thrust as the positive direction, when... When the direction is opposite to the direction of cylinder thrust, .

[0109] A silicon resonant pressure sensor can be used as the pressure sensor. The actual linear velocity at the take-up end can be calculated by detecting the speed of the servo motor at the take-up end using an encoder, and then using the following formula:

[0110] ;

[0111] ;

[0112] ;

[0113] Where R(k) represents the current radius of the take-up end of the roll in the kth sampling period; The motor angular velocity in the kth sampling period can be obtained through an encoder; n(k) represents the motor speed in the kth sampling period; R0 represents the radius of the take-up end roller. This represents the cumulative length of the substrate that has been wound up in the kth sampling period; represents the actual linear velocity of the flexible substrate at the winding end during the i-th sampling period; h represents the thickness of the substrate.

[0114] After the roll material is loaded, the initial linear velocity is determined based on actual working conditions and adjustments. The tension required to maintain the roll tension The roll material begins normal feeding and processing under the drive of the motor. The encoder reads the real-time rotational speed of the motor and converts it into the corresponding linear speed. .

[0115] Taking thin films as an example, assuming that in an extremely short time Within a region, the length of the thin film that enters is... In contrast, the length of the delivered film is When the lengths of the inlet and outlet films at both ends are different, the film will be stretched, generating internal tension. The elongation can be defined as... , where t represents a continuous time variable.

[0116] According to the strain formula and Hooke's law, the change in tension T can be expressed as:

[0117] ;

[0118] Where E represents the elastic modulus of the material, A represents the cross-sectional area of ​​the film, and L represents the controlled span length between the unwinding end and the winding end that participates in tension adjustment.

[0119] This formula shows that the rate of change of tension caused by the roll diameter depends on the difference in linear velocity.

[0120] After performing a Laplace transform on the above equation, we obtain a transfer function:

[0121] ;

[0122] Where s represents the Laplace operator.

[0123] As can be seen from the above formula, the change in tension is an integral element, and the response of tension to linear velocity is delayed.

[0124] If thermal strain is also considered, let the tension deviation of the flexible substrate within the controlled span be... Temperature shock is A temperature function is constructed using a smooth step transition:

[0125] ;

[0126] ;

[0127] The rate of temperature rise is: ;

[0128] in, Indicates the start time; Indicates that the temperature has risen to The time elapsed; This indicates the maximum temperature set on the work platform;

[0129] The thermal shrinkage equivalent coefficient is Then the free thermal strain is:

[0130] ;

[0131] If the film cannot contract freely within the controlled span, the strain will be converted into an equivalent tension change:

[0132] ;

[0133] Taking the derivative with respect to time, we can simplify to obtain the rate of change of the disturbance caused by thermal contraction:

[0134] ;

[0135] in, The unit is N / s. This indicates the residual small-amplitude, nonlinear, high-frequency thermal contraction fluctuations under high-temperature impact.

[0136] The dynamic equation for tension deviation over a small span is:

[0137] ;

[0138] This indicates the velocity correction in the direction of tension release, expressed in m / s. This represents the equivalent buffer time constant of the floating roller, expressed in seconds.

[0139] because = - During the disturbance suppression process, the set tension value remains constant, therefore =0;

[0140] ;

[0141] in, This represents the actual tension at time t; This indicates the preset target tension.

[0142] In actual operation, based on the sampling period Run. Unless otherwise specified, subsequent measurement, filtering, control, compensation, and limiting formulas are all represented using discrete sequences. =k ,x(k)=x( ).

[0143] Based on the above analysis, the dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances provided by this invention, such as... Figure 2 and Figure 3 As shown, it includes the following steps:

[0144] S1, Tension outer loop control: Determine the tension deviation and speed compensation value based on the tension change of the flexible substrate.

[0145] This step uses tension inner loop control to convert tension deviation into a linear speed correction. The actual tension at the unwinding or rewinding end of the flexible substrate is measured and compared with the preset target tension to obtain the current tension deviation; then, the linear speed compensation value is calculated using the proportional-integral nature of the tension loop PI controller.

[0146] This step includes the following sub-steps:

[0147] S11, determine the tension deviation based on the actual tension of the flexible substrate and the preset target tension.

[0148] Based on the film properties, a roll tension requirement is set that can effectively straighten the film without causing deformation or breakage. The actual tension is The resulting tension difference:

[0149] .

[0150] when >0 indicates that the actual tension is higher than the set value.

[0151] In this embodiment, to suppress measurement noise, the actual tension can be subjected to a first-order low-pass filter:

[0152] ;

[0153] in, This represents the actual tension after filtering in the kth sampling period; Represents the filter coefficients. =exp(- ), This represents the filter time constant for tension measurement. This represents the actual tension during the k-th sampling period.

[0154] The tension deviation between the filtered actual tension and the preset target tension is expressed as:

[0155] ;

[0156] The tension difference was normalized to obtain:

[0157] ;

[0158] in, This represents the tension normalization scale.

[0159] S12, based on the tension deviation, obtains the linear velocity compensation value through the tension loop PI controller (because tension itself has an integral element).

[0160] Based on the tension deviation, the linear velocity compensation value is obtained through the tension loop PI controller. , is represented as:

[0161] ;

[0162] in, Indicates the speed calibration scale, Indicates the force proportionality coefficient. Indicates the force integral coefficient. This represents the tension deviation in the k-th sampling period. This represents the tension deviation at time i. Indicates the sampling period.

[0163] Furthermore, regarding Obtain by limiting the amplitude :

[0164] ;

[0165] Represents the amplitude limiting function. , These represent the lower and upper limits of the speed compensation value, respectively.

[0166] The final speed compensation value is output to the inner speed loop and does not directly affect the servo motor speed regulation.

[0167] S2, speed inner loop control: determines the servo motor adjustment command based on linear speed deviation, tension disturbance and thermal disturbance.

[0168] This step uses speed inner loop control to obtain the speed inner loop PID controller output based on the linear speed deviation, and uses tension disturbance and thermal disturbance to compensate for the output to obtain the servo motor adjustment command.

[0169] This step includes the following sub-steps:

[0170] S21 determines the linear speed deviation based on the actual linear speed and the target linear speed; and determines the servo motor pre-adjustment command based on the linear speed deviation through the speed loop PID controller.

[0171] Given a base linear velocity, the target linear velocity is obtained by weighted fusion of the base linear velocity and the linear velocity compensation value, expressed as:

[0172] ;

[0173] in, Indicates the target linear velocity. Indicates the basic linear velocity. This represents the velocity compensation direction coefficient.

[0174] The difference between the actual linear velocity and the target linear velocity is taken as the linear velocity deviation, and is expressed as:

[0175] ;

[0176] in, Indicates the actual linear velocity;

[0177] Based on the linear velocity deviation, the output obtained through the speed loop PID controller is the servo motor pre-adjustment command:

[0178] ;

[0179] in, Indicates the speed proportionality coefficient. Represents the velocity integral coefficient. Represents the velocity differential coefficient. This represents the velocity integral term.

[0180] S22, construct a tension damping compensation term based on the tension change rate of the flexible substrate.

[0181] In practical control, it is impossible to obtain material properties E, A, L, and temperature-related information accurately and in real time. This embodiment uses the tension change information obtained at each sampling time to approximate the tension by difference between each adjacent sampling period, and defines the discrete tension change rate as the disturbance prediction quantity:

[0182] ;

[0183] in, ,0< <1; This represents the rate of change of tension during the k-th sampling period; This represents the time constant for the tension change rate filtering. During initialization, D can be set... F (0)=0.

[0184] Construct a tension damping compensation term based on the rate of change of tension:

[0185] ;

[0186] in, The damping coefficient represents the rate of change of tension. This indicates the tension normalization scale. This parameter allows the system to proactively correct the motor drive when it detects a rapid increase or decrease in tension, rather than waiting for speed errors to accumulate before making adjustments.

[0187] S23, construct a thermal disturbance feedforward compensation term based on the rate of change of thermal disturbance caused by the thermal shrinkage of the flexible substrate.

[0188] To address the thermal contraction disturbance caused by temperature shock, a thermal disturbance feedforward compensation term is introduced:

[0189] ;

[0190] ;

[0191] in, This represents the thermal disturbance compensation coefficient. This represents the rate of change of thermal disturbance in the k-th sampling period; This represents the actual temperature of the flexible substrate measured in the kth sampling period. Specifically, it can measure the actual temperature of the flexible substrate at the winding end or unwinding end, for example, using a non-contact temperature sensor (such as an infrared temperature sensor) at a location downstream of the area affected by thermal disturbance (e.g., ...). Figure 1 The surface temperature of the flexible substrate is measured (above the substrate at the transition roller). This step corrects the motor output in advance during periods of rapid temperature change, reducing sudden tension changes caused by high-temperature shocks.

[0192] S24, based on the servo motor pre-adjustment command, tension damping compensation term and thermal disturbance feedforward supplement term, the servo motor adjustment command is obtained by weighted fusion.

[0193] By adding tension damping compensation and thermal disturbance feedforward supplementary terms to the servo motor pre-adjustment command, the final servo motor adjustment command is obtained:

[0194] ;

[0195] in, and These represent the direction coefficients for compensation of the rate of change of tension and thermal disturbance, respectively.

[0196] Furthermore, regarding Obtain by limiting the amplitude This ensures that the output signal meets the driver's allowable range.

[0197] ;

[0198] in, , These represent the lower and upper limits of the servo motor adjustment command, respectively. The servo motor adjustment command is limited and represents the equivalent acceleration in this invention.

[0199] Furthermore, the integral term After antisaturation correction, it becomes:

[0200] ;

[0201] in, Indicates the coefficient against integral saturation; , These are the actual outputs before and after the amplitude limiting at time k-1, respectively.

[0202] S3, based on the tension deviation determined in step S1, adjust the tension on the flexible substrate.

[0203] This invention primarily relies on tension deviation to regulate the tension on the flexible substrate by adjusting a floating roller. Specifically, the air pressure of the cylinder supporting the floating roller is adjusted (by providing inflation / deflation), thereby altering the supporting and buffering effect of the floating roller on the flexible substrate, thus reducing transient tension fluctuations and ensuring stable roll material transport.

[0204] The tension release rate achieved by the pneumatic floating roller is:

[0205] ;

[0206] This represents the equivalent buffer time constant of the pneumatic floating roller.

[0207] S4. Based on the servo motor adjustment command determined in step S2, adjust the speed of the servo motor at the take-up end or the unwinding end.

[0208] The servo motor adjustment command is the equivalent linear acceleration. Dividing it by the winding diameter at the take-up or unwinding end gives the servo motor angular acceleration, which in turn determines the change in servo motor speed, thereby adjusting the servo motor speed.

[0209] By repeating steps S1-S4 above, as the rate of temperature change decreases and the thermal shock gradually subsides, the tension deviation ΔF and the linear velocity compensation value... and thermal disturbance compensation amount All gradually decrease, and the target linear velocity recovers to near the set base linear velocity, continuing to maintain closed-loop operation.

[0210] To verify the effectiveness of the method of the present invention, three control models were constructed: single-loop PID, speed-tension series PID control, and dual closed-loop PID control, and were verified in a simulation environment.

[0211] Single-loop PID refers to a single tension closed-loop control method that directly outputs the speed correction amount based solely on the tension deviation. It does not set up an independent speed inner loop, nor does it introduce tension change rate damping compensation or thermal disturbance feedforward compensation (i.e., equivalent to step S1).

[0212] Speed-tension cascade PID control replaces steps S22 to S24 in step S2 above with the following process: the outer tension loop obtains the speed correction amount based on the tension deviation, and then the inner speed loop tracks and corrects it. The tension change rate during motion and the tension change caused by thermal disturbance are not introduced into the speed loop but are directly absorbed by the tension loop (i.e., The tension outer ring and the speed inner ring operate independently.

[0213] Dual closed-loop PID control refers to executing steps S1-S4 as described above.

[0214] The parameter settings are as follows:

[0215] The general physical parameters are: elastic modulus E = 2.5 GPa, film width w = 100 mm, film thickness h = 25 μm, controlled span L = 0.50 m, cross-sectional stiffness EA = 6250 N, and velocity-tension rate of change coefficient. =12500 N / m, thermal shrinkage equivalent coefficient =3.0×10 -5 / ℃. The temperature shock amplitude is taken from 0-100℃, and scanned once every 10℃; the temperature shock start time t0=0.20s, the heating time t=50ms, the simulation step size Δt=1ms, and the total simulation time is 2.0s. Tension calibration scale. =20N, speed calibration scale =0.035m / s, and the recovery criterion is that the tension deviation enters the ±0.5N range and remains stable. In the simulation, the physical parameters and disturbance inputs of the flexible substrate are constructed based on the above parameters.

[0216] The PID and actuator parameters are as follows:

[0217] Single-loop PID, using =0.42、 =1.10、 =0.010, speed correction limit ±0.024m / s, direct speed regulation execution time constant 0.150s, acceleration limit ±0.18m / s², tension measurement filter time constant Only retain the weak natural buffer τ b =3.0s.

[0218] Speed-tension series PID control, tension loop PI control, =0.52、 =1.70, speed given limit ±0.030m / s; speed loop =32.0、 =220.0、 =0.015, acceleration limit ±0.62m / s², tension measurement filter time constant No pneumatic floating roller is installed for rapid buffering. b =3.0s.

[0219] Dual closed-loop PID control, with tension outer loop PI. =0.64、 =2.60, speed given limit ±0.035m / s; speed inner loop =46.0、 =360.0、 =0.020, acceleration limit ±1.35m / s², tension measurement filter time constant Pneumatic floating roller buffer =0.085s.

[0220] Simulation results are as follows Figures 4-6 As shown.

[0221] In the stability verification without high-frequency disturbances, the temperature shock amplitude was set to 0℃ and the initial tension deviation was set to 5.0N. All three schemes were able to recover to within the ±0.5N threshold, indicating that the selected control parameters will not cause divergence or continuous oscillation when there are no external high-frequency disturbances.

[0222] Under a temperature disturbance of 100℃, the peak tension deviation of the dual-closed-loop PID control scheme is 12.88N, which is about 29.4% lower than the 18.24N of the single-loop PID and about 27.0% lower than the 17.65N of the speed-tension cascade PID control scheme. The recovery time is 0.619s, which is about 62.0% shorter than the 1.630s of the single-loop PID and about 25.1% shorter than the 0.826s of the speed-tension cascade PID control scheme. Furthermore, compared to single-loop PID and speed-tension cascade PID control, the speed correction of the dual-closed-loop PID control scheme in this embodiment is more concentrated in the initial stage of the disturbance, resulting in lower tension fluctuation amplitude and faster decay.

[0223] The above results demonstrate that the high-frequency buffering, thermal disturbance residual calculation, and dynamic limiting speed servo of the pneumatic floating roller can effectively reduce the continuous impact of high-temperature transient disturbances on the tension system and shorten the tension recovery time.

[0224] Example 2

[0225] This embodiment provides a dual-closed-loop control system for suppressing high-frequency transient nonlinear tension disturbances, used to implement the dual-closed-loop method for suppressing high-frequency transient nonlinear tension disturbances in Embodiment 1, which includes:

[0226] Tension outer ring control unit: used to determine tension deviation and linear velocity compensation values ​​based on the tension changes experienced by the flexible substrate; the tension outer ring control unit includes:

[0227] The tension deviation calculation module is used to determine the tension deviation based on the actual tension of the flexible substrate and the preset target tension.

[0228] The linear velocity compensation generation module is used to obtain the linear velocity compensation value based on the tension deviation through the tension loop PI controller;

[0229] Speed ​​inner loop control unit: used to determine servo motor adjustment commands based on linear speed deviation, tension disturbance, and thermal disturbance; this speed inner loop control unit includes:

[0230] The servo motor pre-adjustment command generation module is used to determine the linear speed deviation based on the actual linear speed and the target linear speed; and based on the linear speed deviation, it determines the servo motor pre-adjustment command through the speed loop PID controller.

[0231] The tension damping compensation term construction module is used to construct tension damping compensation terms based on the tension change rate of the flexible substrate.

[0232] A thermal disturbance feedforward compensation term construction module is used to construct thermal disturbance feedforward compensation terms based on the rate of change of thermal disturbance caused by thermal shrinkage of flexible substrates.

[0233] The servo motor adjustment command generation module is used to obtain the servo motor adjustment command by weighted fusion of the servo motor pre-adjustment command, tension damping compensation term and thermal disturbance feedforward supplement term.

[0234] The tension adjustment unit is used to adjust the tension on the flexible substrate based on the tension deviation.

[0235] The servo motor adjustment unit is used to adjust the speed of the servo motor at the take-up end or the unwinding end according to the servo motor adjustment command.

[0236] The above modules and units perform operations according to steps S1-S4 given in the previous dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances.

[0237] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances, applicable to the winding and unwinding processes of flexible substrates, characterized in that, Includes the following steps: S1, Tension outer loop control: Determine the tension deviation and speed compensation value based on the tension change of the flexible substrate; This step includes the following sub-steps: S11, determine the tension deviation based on the actual tension of the flexible substrate and the preset target tension; S12, based on the tension deviation, obtains the linear velocity compensation value through the tension loop PI controller; S2, speed inner loop control: determines the servo motor adjustment command based on linear speed deviation, tension disturbance and thermal disturbance; This step includes the following sub-steps: S21, determine the linear velocity deviation based on the actual linear velocity and the target linear velocity; Based on the linear velocity deviation, the servo motor pre-adjustment command is determined through the speed loop PID controller; S22, construct a tension damping compensation term based on the tension change rate of the flexible substrate; S23, construct a thermal disturbance feedforward compensation term based on the rate of change of thermal disturbance caused by thermal shrinkage of flexible substrate; S24, the servo motor adjustment command is obtained by weighted fusion of the servo motor pre-adjustment command, tension damping compensation term and thermal disturbance feedforward supplement term; S3, Based on the tension deviation determined in step S1, adjust the tension on the flexible substrate; S4. Based on the servo motor adjustment command determined in step S2, adjust the speed of the servo motor at the take-up end or the unwinding end.

2. The dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 1, characterized in that, In step S11, a floating roller for adjusting or buffering tension is provided near the unwinding end and / or the winding end of the flexible substrate, and the floating roller is supported by a cylinder; a pressure sensor is provided inside the cylinder to collect gas pressure, and then the actual tension on the flexible substrate is calculated: ； ； in, This represents the actual tension during the k-th sampling period; This indicates the thrust of the cylinder; This represents the air pressure detected by the pressure sensor during the kth sampling period; This indicates the effective pressure-bearing area of ​​the cylinder piston; The equivalent conversion factor from pressure to tension; This indicates the weight of the floating roller.

3. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 2, characterized in that, Filter the actual pressure: ； in, This represents the actual tension after filtering in the kth sampling period; Represents the filter coefficients. =exp(- ), This represents the time constant of the tension measurement filter. Indicates the sampling period; This represents the actual tension during the k-th sampling period; The normalized result of the difference between the actual tension of the flexible substrate and the preset target tension is taken as the tension deviation, denoted as . .

4. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 3, characterized in that, In step S12, based on the tension deviation, the linear velocity compensation value is obtained through the tension loop PI controller. , represented as: ； in, Indicates the speed calibration scale, Indicates the force proportionality coefficient. Indicates the force integral coefficient. This represents the tension deviation in the k-th sampling period. This represents the tension deviation during the i-th sampling period.

5. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 4, characterized in that, right Obtain by limiting the amplitude : ； in, Represents the amplitude limiting function. , These represent the lower and upper limits of the speed compensation value, respectively.

6. The dual-closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to any one of claims 1 to 5, characterized in that, In step S21, given the base linear velocity, the target linear velocity is obtained by weighted fusion of the base linear velocity and the linear velocity compensation value, expressed as: ； in, Indicates the target linear velocity. Indicates the basic linear velocity. Indicates the velocity compensation direction coefficient. This represents the linear velocity compensation value after amplitude limiting; The difference between the actual linear velocity and the target linear velocity is taken as the linear velocity deviation, and is expressed as: ； in, Indicates the actual linear velocity; Based on the linear velocity deviation, the output obtained through the speed loop PID controller is the servo motor pre-adjustment command: ； in, Indicates the speed proportionality coefficient. Represents the velocity integral coefficient. Represents the velocity differential coefficient. This represents the velocity integral term.

7. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 6, characterized in that, In step S22, the discrete tension change rate is defined as follows: ； in, ,0< <1; This represents the rate of change of tension during the k-th sampling period; This represents the time constant for the tension change rate filter. Construct a tension damping compensation term based on the rate of change of tension: ； in, Indicates the damping coefficient representing the rate of change of tension; This represents the tension normalization scale.

8. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 7, characterized in that, In step S23, a thermal disturbance feedforward compensation term is introduced to address the thermal contraction disturbance caused by temperature shock: ； ； in, Indicates the thermal disturbance compensation coefficient; This represents the rate of change of thermal disturbance in the k-th sampling period; This represents the actual temperature of the flexible substrate measured in the kth sampling period.

9. The dual closed-loop control method for suppressing high-frequency transient nonlinear tension disturbances according to claim 8, characterized in that, In step S24, tension damping compensation and thermal disturbance feedforward supplementation terms are added to the servo motor pre-adjustment command to obtain the final servo motor adjustment command: ； in, and These represent the direction coefficients for compensation of the rate of change of tension and the direction coefficients for compensation of thermal disturbance, respectively. right Obtain by limiting the amplitude : ； in, , These represent the lower and upper limits of the servo motor adjustment command, respectively. Integral term After antisaturation correction, it becomes: ； in, Indicates the coefficient against integral saturation; , These are the actual outputs before and after the amplitude limiting at time k-1, respectively.

10. A dual-closed-loop control system for suppressing high-frequency transient nonlinear tension disturbances, characterized in that, To implement the method according to any one of claims 1 to 9, comprising: Tension outer ring control unit: used to determine tension deviation and linear velocity compensation values ​​based on the tension changes experienced by the flexible substrate; the tension outer ring control unit includes: The tension deviation calculation module is used to determine the tension deviation based on the actual tension of the flexible substrate and the preset target tension. The linear velocity compensation generation module is used to obtain the linear velocity compensation value based on the tension deviation through the tension loop PI controller; Speed ​​inner loop control unit: used to determine servo motor adjustment commands based on linear speed deviation, tension disturbance, and thermal disturbance; this speed inner loop control unit includes: The servo motor pre-adjustment command generation module is used to determine the linear speed deviation based on the actual linear speed and the target linear speed; and based on the linear speed deviation, it determines the servo motor pre-adjustment command through the speed loop PID controller. The tension damping compensation term construction module is used to construct tension damping compensation terms based on the tension change rate of the flexible substrate. A thermal disturbance feedforward compensation term construction module is used to construct thermal disturbance feedforward compensation terms based on the rate of change of thermal disturbance caused by thermal shrinkage of flexible substrates. The servo motor adjustment command generation module is used to obtain the servo motor adjustment command by weighted fusion of the servo motor pre-adjustment command, tension damping compensation term and thermal disturbance feedforward supplement term. The tension adjustment unit is used to adjust the tension on the flexible substrate based on the tension deviation. The servo motor adjustment unit is used to adjust the speed of the servo motor at the take-up end or the unwinding end according to the servo motor adjustment command.

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