Pay-off tension control system and control method of stranding machine

Abstract

The invention relates to the technical field of wire and cable manufacturing, in particular to a stranding machine pay-off tension control system and method, and the method comprises the steps: calculating the steady-state rotation resistance holding value and the dynamic comprehensive inertia load of each shaft; a set is constructed based on the steady-state rotation resistance holding value of each shaft, a group median reference value is determined, and a differential compensation torque is generated according to the group median reference value; calculating the maximum load ratio shaft occupancy rate by using the steady-state rotation resistance retention value and the dynamic comprehensive inertia load, and correcting the original acceleration instruction to obtain the limited acceleration when the maximum load ratio shaft occupancy rate exceeds the limit; and finally, the differential compensation torque and the inertia feed-forward torque based on the limited acceleration are fused to generate an execution instruction. Different shafts are dynamically compensated through group reference, the acceleration is limited in real time through load feedback, the tension fluctuation and overload risks in multi-shaft synchronization are effectively solved, high-precision constant tension control and stable acceleration and deceleration are achieved, and cable quality and equipment safety are improved.

Description

Technical Field

[0001] This invention relates to the field of wire and cable manufacturing technology, and specifically to a stranding machine tension control system and control method. Background Technology

[0002] In wire and cable manufacturing, rigid cage stranding machines use the rotation of the cage to drive multiple pay-off reels to rotate synchronously, stranding multiple single wires into a cable. The key to the quality of the cable lies in the dynamic consistency of the tension on each pay-off reel. Currently, two main control schemes are used: one is open-loop control with unified commands, which sends the same torque command to all motors. However, due to individual differences in the assembly tightness and wear of each pay-off shaft, the actual tension is uneven. The other is closed-loop control based on sensors. Although it can achieve precise adjustment through real-time feedback, it requires a large number of tension sensors, which is costly and complex to maintain.

[0003] In actual operating conditions, tension control also faces two types of mixed interference: on the one hand, changes in ambient temperature cause a uniform change in the viscosity of all bearing grease, leading to overall frictional resistance drift; on the other hand, the inherent mechanical differences of each shaft bring about individual resistance fluctuations. Existing technology cannot effectively separate these two types of interference from the motor torque without increasing sensor costs, resulting in fixed compensation values ​​being unable to adapt to overall drift. This easily leads to problems such as overcompensation during cold starts or undercompensation during warm-up operation. At the same time, the shaft with the heaviest load often breaks due to torque saturation during acceleration and deceleration.

[0004] Therefore, how to adaptively separate environmental influences and individual differences and constrain system shortcomings without relying on additional sensors to improve the stability of operation under all conditions has become an urgent technical problem to be solved. Summary of the Invention

[0005] To address the technical problem of low dynamic control accuracy of stranding machines under all operating conditions due to the combined effects of environmental interference and individual differences on the pay-off tension, the present invention aims to provide a stranding machine pay-off tension control system and method. The specific technical solution adopted is as follows: One embodiment of the present invention provides a method for controlling the wire feeding tension of a stranding machine, the method comprising the following steps: Based on the operating characteristics of the current control cycle, determine the steady-state rotational resistance holding value and dynamic comprehensive inertial load of each wire-feeding shaft in the current control cycle; Obtain a set of resistance characteristics consisting of the steady-state rotational resistance holding values ​​of all pay-off shafts, and determine the group median reference value of the standard resistance level under the current environmental conditions based on the set of resistance characteristics. Based on the difference between the steady-state rotational resistance value of each pay-off shaft and the group median reference value, the differentiated compensation torque of each pay-off shaft in the current control cycle is determined; The maximum load percentage shaft occupancy rate is determined based on the steady-state rotational resistance holding value and the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle. Based on the comparison between the maximum load ratio axis occupancy rate and the preset safe load threshold, the acceleration command of the system virtual spindle in the current cycle is corrected to obtain the limited acceleration in the current control cycle. Based on the differentiated compensation torque of each pay-off axis in the current control cycle, and combined with the inertial feedforward torque determined based on the restricted post-acceleration, the final execution torque command for each pay-off axis in the current control cycle is determined.

[0006] Furthermore, determining the steady-state rotational resistance holding value and dynamic comprehensive inertial load of each wire-feeding shaft in the current control cycle based on the operating characteristics of the current control cycle includes: Obtain the acceleration command and real-time speed of the main traction motor inside the stranding machine under the current control cycle; Based on the acceleration command and real-time rotation speed of the current control cycle, the operating condition of the stranding machine under the current control cycle is determined; wherein, the operating condition is a steady-state sampling interval or a transient sampling interval; When the steady-state sampling interval is determined, for each pay-off shaft of the stranding machine, the steady-state rotational resistance holding value of each pay-off shaft in the current control cycle is determined based on the difference between the set tension braking torque and the actual output torque of the motor in the current cycle; and the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle is assigned to zero. When the transient sampling interval is determined, for each pay-off shaft of the stranding machine, the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle is determined based on the set tension braking torque, the actual output torque of the motor, and the steady-state rotational resistance holding value of the current cycle; wherein, the steady-state rotational resistance holding value of each pay-off shaft in the current control cycle is equal to the steady-state rotational resistance holding value in the previous control cycle.

[0007] Further, determining the operating condition of the stranding machine in the current control cycle based on the acceleration command and real-time rotation speed of the current control cycle includes: Set acceleration and rotation speed thresholds; When the absolute value of the acceleration command is less than or equal to the acceleration threshold, and the absolute value of the real-time rotation speed is greater than the rotation speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a steady-state sampling interval. When the absolute value of the acceleration command is greater than the acceleration threshold, or the absolute value of the real-time rotation speed is less than or equal to the rotation speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a transient sampling interval.

[0008] Furthermore, determining the dynamic comprehensive inertial load of each wire-feeding shaft in the current control cycle based on the set tension braking torque, the actual output torque of the motor, and the steady-state rotational resistance holding value of the current cycle includes: Calculate the difference between the absolute value of the set tension braking torque and the steady-state rotational resistance holding value of the same wire feeding shaft, and use it as the motor's basic torque; The absolute value of the difference between the actual output torque of the motor and the basic torque of the motor is determined as the dynamic comprehensive inertial load of the corresponding wire-laying shaft in the current control cycle.

[0009] Further, determining the group median reference value of the standard resistance level under the current environmental conditions based on the resistance characteristic set includes: Based on the steady-state rotational resistance and angular velocity of the same wire-feeding shaft in the current control cycle, determine the unit damping coefficient of each wire-feeding shaft; Using the unit damping coefficient of each wire feeding shaft, all steady-state rotational resistance values ​​in the resistance characteristic set are sorted in a preset order to obtain an ordered resistance sequence; The median of the ordered resistance sequence is determined, and the median is used as the median benchmark value of the population.

[0010] Further, determining the differentiated compensation torque for each pay-off shaft in the current control cycle based on the difference between the steady-state rotational resistance value of each pay-off shaft and the group median reference value includes: Based on the difference between the steady-state rotational resistance holding value of the same pay-off shaft and the group median reference value, the individual wear resistance deviation value of each pay-off shaft in the current control cycle is determined; Set a resistance deviation threshold. When the absolute value of the individual wear resistance deviation value of a certain wire-feeding shaft is less than the resistance deviation threshold, the differential compensation torque of the corresponding wire-feeding shaft in the current control cycle is assigned to zero. When the absolute value of the individual wear resistance deviation of a certain pay-off shaft is greater than or equal to the resistance deviation threshold, the differentiated compensation torque is determined based on the individual wear resistance deviation of the corresponding pay-off shaft and the preset compensation gain coefficient.

[0011] Further, determining the maximum load-percentage shaft occupancy rate based on the steady-state rotational resistance holding value and the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle includes: For each pay-off shaft, calculate the combined value of the steady-state rotational resistance holding value, the dynamic comprehensive inertial load, and the set tension braking torque, and denote it as the total electromagnetic torque; Based on the total electromagnetic torque and the torque parameters of the rated peak output of the introduced servo motor, determine the rated capacity occupancy rate of the wire feeding shaft motor; Select the maximum value among all the motor rated capacity occupancy rates of the wire feeding shafts, and determine the maximum value as the maximum load occupancy rate of the shaft.

[0012] Further, the step of correcting the acceleration command of the system virtual spindle in the current cycle based on the comparison result of the maximum load ratio axis occupancy rate and the preset safe load threshold, to obtain the limited acceleration for the current control cycle, includes: If the maximum load percentage axis occupancy rate is greater than the preset safe load threshold, the acceleration command of the system virtual spindle in the current cycle is weighted using the correction coefficient determined by the preset safe load threshold and the maximum load percentage axis occupancy rate to obtain the limited acceleration for the current control cycle. If the maximum load percentage axis occupancy rate is less than or equal to the preset safe load threshold, then based on the preset acceleration recovery rate limiting strategy, the acceleration command of the system virtual spindle in the current control cycle is limited to obtain the limited acceleration command. The acceleration recovery rate limiting strategy is configured to: limit the change in the current cycle's post-limited acceleration command relative to the previous cycle's post-limited acceleration command to not exceed a preset recovery threshold, and ensure that the amplitude of the post-limited acceleration command is not greater than the amplitude of the system's virtual spindle's acceleration command.

[0013] Further, determining the final execution torque command for each pay-off axis in the current control cycle based on the differentiated compensation torque of each pay-off axis in the current control cycle, combined with the inertial feedforward torque determined based on the limited acceleration, includes: Obtain the set tension braking torque for each wire feeding shaft in the current control cycle; The differential compensation torque, the set tension braking torque, and the inertial feedforward torque of the same pay-off shaft are fused to obtain a fused value, and the fused value is determined as the final execution torque command of the corresponding pay-off shaft in the current control cycle. The inertial feedforward torque is equal to the product of the real-time rotational inertia of the same wire-laying shaft in the current control cycle and the acceleration after limitation.

[0014] Another embodiment of the present invention provides a stranding machine tension control system, including a processor and a memory, wherein the processor is used to process instructions stored in the memory to implement a stranding machine tension control method.

[0015] The present invention has the following beneficial effects: To address the problem of mixed interference caused by overall frictional drift and mechanical differences between axes due to ambient temperature, this invention utilizes a group median reference value to automatically characterize the overall basic resistance by following environmental changes. Only the difference between each axis and this reference value is used as the differential compensation torque. This effectively separates common-mode environmental interference from individual mechanical discreteness without adding sensors, and to some extent solves the defects of fixed compensation values, such as excessive compensation during cold starts and insufficient compensation during hot runs, achieving adaptive and precise control across the entire temperature range. Addressing the pain point of the heaviest-loaded axis being prone to breakage due to torque saturation during acceleration and deceleration, this invention calculates the occupancy rate of the axis with the highest load percentage in real time and dynamically corrects the limited acceleration accordingly. This strategy forces the system's acceleration capability to be determined by the weakest axis under the most severe operating conditions, ensuring that the combined torque of the heaviest-loaded axis is not saturated under any transient condition, thus eliminating follow-lag and breakage accidents caused by insufficient torque on individual axes at the source. By deeply integrating inertial feedforward based on limited acceleration with compensation torque tailored to individual differences, this invention achieves precise matching between dynamic response and static correction. It avoids feedforward overshoot caused by acceleration limiting and ensures compensation is unaffected by environmental common-mode interference, significantly improving the tension control accuracy and operational reliability of stranding machines under complex mixed interference such as temperature variations, wear, and drastic speed changes. In summary, this invention effectively solves the tension fluctuation and overload risk in multi-axis synchronization by dynamically compensating for differences between axes using a group benchmark and utilizing load feedback to limit acceleration in real time. This achieves high-precision constant tension control and smooth acceleration / deceleration, improving cable quality and equipment safety. Attached Figure Description

[0016] To more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the steps of a stranding machine tension control method according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating the steps of determining the group median reference value of the standard resistance level under the current environmental conditions based on the resistance feature set in an embodiment of the present invention. Figure 3 This is a flowchart illustrating the steps for determining the maximum load percentage axis occupancy rate in an embodiment of the present invention. Detailed Implementation

[0018] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the specific implementation methods, structures, features, and effects of the technical solution proposed according to the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0020] The application scenarios targeted by this invention can be: In multi-axis coordinated wire feeding scenarios such as stranding machines, existing control solutions mainly face three challenges: First, it is difficult to adapt to individual differences. Traditional uniform torque commands cannot distinguish the damping characteristics of each pay-off shaft, resulting in insufficient actual tension on high-damping shafts. Second, it has poor environmental adaptability. Fixed resistance compensation strategies are difficult to cope with the overall resistance drift caused by temperature changes, which can easily lead to overcompensation when the machine is cold or undercompensation when the machine is hot. While introducing tension sensors can improve the closed-loop effect, it significantly increases the system cost and maintenance complexity. Third, it has weak dynamic following capability. During acceleration and deceleration, if the load rate difference of each shaft is not considered, the heavy-load shaft is very likely to lose synchronization due to torque saturation, causing wire breakage and shutdown.

[0021] Therefore, accurately decoupling and separating environmental drift and individual variation components from the total motor torque without additional sensor support, and then adaptively constraining and compensating for system shortcomings, has become a key requirement for improving equipment operational stability and process consistency. To this end, one embodiment of the present invention provides a method for controlling the wire feeding tension of a stranding machine, such as... Figure 1 As shown.

[0022] Before performing load calculations for each axis, the basic physical parameters must be obtained: Real-time roll diameter: The real-time roll diameter of each pay-off spool is measured by integrating the spindle traction linear speed over time (linear speed / angular velocity relationship) or by directly measuring the roll diameter of each pay-off spool through an external displacement sensor / ultrasonic sensor.

[0023] Real-time rotational inertia: Based on the real-time roll diameter, combined with the preset empty shaft rotational inertia and wire density parameters, the total rotational inertia of the current pay-off shaft is calculated.

[0024] Setting tension braking torque: Based on the product of the preset target process tension value and the real-time roll diameter, determine the set tension braking torque required to maintain constant tension in the current control cycle.

[0025] S1, based on the operating characteristics of the current control cycle, determine the steady-state rotational resistance holding value and dynamic comprehensive inertial load of each wire-laying shaft in the current control cycle.

[0026] Since static friction exists only during the stationary phase of the equipment, and inertial torque is significant only during the variable speed phase, direct measurement would interfere with the extraction of constant mechanical friction characteristics. Therefore, this embodiment identifies two key parameters differently based on the motion state of the current control cycle, i.e., the operating condition characteristics: extracting the steady-state rotational resistance holding value in the uniform or quasi-uniform speed segment to characterize pure friction characteristics, and calculating the dynamic comprehensive inertial load in the acceleration and deceleration segment to quantify the dynamic load, thereby achieving accurate modeling under all operating conditions.

[0027] It is important to clarify that the motor output driving torque is positive, while the braking or generating torque is negative. All subsequent addition and subtraction operations in the formulas must conform to this physical meaning.

[0028] As an exemplary implementation, taking any pay-off spool as an example, determining the steady-state rotational resistance hold-up value and dynamic combined inertial load of the pay-off spool in the current control cycle includes: The first step is to obtain the acceleration command and real-time speed of the main traction motor inside the stranding machine under the current control cycle.

[0029] In this embodiment, the control cycle is triggered by the PLC (Programmable Logic Controller) hard real-time scan task clock, typically set to 10ms-20ms. At the start sampling moment of the current control cycle, the PLC simultaneously stores and locks the spindle acceleration command and feedback speed to ensure that the command value and feedback value are at the same physical timestamp.

[0030] It should be noted that the system control frequency is much higher than the mechanical response frequency, and a single snapshot of data is sufficient to represent the current physical state. If multi-point sampling or sliding window averaging is used, significant computational phase lag will be introduced, reducing the real-time performance of tension adjustment and causing oscillations in the control system.

[0031] The second step is to determine the operating condition of the stranding machine under the current control cycle based on the acceleration command and real-time rotation speed of the current control cycle.

[0032] Here, the operating conditions are either steady-state sampling intervals or transient sampling intervals. These are two mutually exclusive sampling intervals. In the steady-state sampling interval, the equipment is in a stable rotating state with near-zero acceleration and has overcome static friction, making it suitable for extracting dynamic friction resistance characteristics. In the transient sampling interval, the equipment is in an accelerating, decelerating, or stationary / very low-speed state, exhibiting significant inertial loads or static friction nonlinearities, making it unsuitable for updating resistance data.

[0033] Specifically, acceleration threshold and rotational speed threshold are set; when the absolute value of the acceleration command is less than or equal to the acceleration threshold and the absolute value of the real-time rotational speed is greater than the rotational speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a steady-state sampling interval; when the absolute value of the acceleration command is greater than the acceleration threshold, or the absolute value of the real-time rotational speed is less than or equal to the rotational speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a transient sampling interval.

[0034] In this embodiment, an acceleration threshold is set. It is used to determine whether the equipment is in a constant speed state. This value is usually set to 1% to 2% of the maximum acceleration of the motor (e.g., To tolerate minor command jitter; set a speed threshold. It is used to determine whether the equipment has moved out of the static friction zone, and this value is usually set to 5% of the motor's rated speed (e.g., ).

[0035] Taking the k-th control cycle as the current control cycle, determine the operating condition of the stranding machine under the current control cycle, including: When the absolute value of the acceleration command in the k-th control cycle simultaneously meets the conditions And the absolute value of the real-time speed in the kth control cycle When the system enters the steady-state sampling range, the device is in a stable rotational state with an acceleration of approximately zero and has overcome static friction, making it suitable for extracting dynamic friction resistance characteristics.

[0036] When the absolute value of the acceleration command in the k-th control cycle simultaneously meets the conditions , or the absolute value of the real-time rotational speed in the k-th control cycle. When the system enters the transient sampling interval, it is determined that the equipment is in an accelerating, decelerating, or stationary / very low-speed state, with significant inertial load or static friction nonlinearity, which is not suitable for updating resistance data.

[0037] The third step is to determine the steady-state rotational resistance and dynamic comprehensive inertial load of the wire feeding shaft in the current control cycle based on the operating conditions of the stranding machine under the current control cycle.

[0038] Here, the dynamic composite inertial load is used to comprehensively characterize the resultant torque deviation caused by the inertial load and dynamic tension fluctuations.

[0039] Determining the steady-state rotational resistance hold-up value and the dynamic comprehensive inertial load is crucial for constructing an engineering characteristic observation model from the mixed actual motor torque. This model enables differentiated identification and mapping of the equivalent resistance component reflecting temperature / wear conditions and the inertial torque component reflecting acceleration / deceleration conditions. Instead of relying on precise stripping of absolute physical resistance, this model treats the steady-state torque residual as an equivalent characteristic value encompassing frictional features and steady-state tension error. Through group comparison logic in subsequent steps, common-mode interference is offset and the relative deviations between axes are locked. Specifically, based on the operating conditions, the motor torque signal is mapped to equivalent features. The equivalent resistance characteristic value is extracted and updated under steady-state conditions, and the inertial component is identified using the locked resistance benchmark under transient conditions. The steady-state rotational resistance hold-up value characterizes the current comprehensive mechanical resistance level of the pay-off shaft (including frictional resistance and steady-state tension error). Because this characteristic value is mixed with environmental temperature drift (common-mode interference) and individual wear deviation (differential-mode interference), it is necessary to derive a lateral group comparison logic from it to isolate the environmental influence; the dynamic comprehensive inertial load is used to quantify the extra burden on the motor to overcome rotational inertia under dynamic operating conditions. Due to the different winding diameters of each pay-off spool, the motor load is extremely unbalanced during the dynamic process. By combining this component with resistance characteristics and tension requirements, the rated capacity utilization rate of the motor, which reflects the real-time load limit, can be calculated.

[0040] When the sampling interval is determined to be steady state, for each wire feeding shaft of the stranding machine, the steady state rotational resistance holding value of each wire feeding shaft in the current control cycle is determined based on the difference between the set tension braking torque and the actual output torque of the motor in the current cycle; and the dynamic comprehensive inertial load of each wire feeding shaft in the current control cycle is assigned to zero.

[0041] When in the steady-state sampling range, according to Newton's laws of motion, the motor's angular acceleration is zero, and no output torque is needed to overcome the moment of inertia. At this time, the torque balance equation for the pay-off shaft is: the total tension requirement equals the sum of the motor's electromagnetic braking torque and the mechanical friction resistance torque; that is, the mechanical friction resistance objectively plays an auxiliary role in braking the motor. Subtracting the actual electromagnetic torque exerted by the motor from the theoretically required total braking torque, the remaining portion is the resistance torque provided by mechanical friction.

[0042] For the i-th wire feeding axis, obtain the actual output torque of the motor fed back by the servo driver under the current control cycle, and the set tension braking torque calculated according to process requirements, and then update the steady-state rotational resistance holding value, including: The first step is to determine the original steady-state rotational resistance holding value of the i-th wire feeding shaft in the current control cycle based on the difference between the set tension braking torque and the actual output torque of the motor in the current cycle.

[0043] Within the steady-state uniform speed operating range, assuming that the actual tension dynamic error of each wire-laying shaft has converged and remained relatively constant, the difference between the theoretically set braking torque and the actual output torque of the motor (i.e., torque residual) is taken as the current equivalent resistance characteristic of the wire-laying shaft, i.e., the original steady-state rotational resistance retention value.

[0044] As an example, the formula for calculating the original steady-state rotational resistance value of the i-th wire-feeding shaft in the current control cycle can be: In the formula, This represents the initial steady-state rotational resistance value maintained by the i-th wire-feeding shaft in the current control cycle. This represents the set tension braking torque of the i-th wire feeding shaft in the current control cycle. This represents the total braking demand of the i-th wire feeding shaft in the current control cycle. This represents the actual output torque of the motor for the i-th wire feeding shaft in the current control cycle. This represents the magnitude of the electromagnetic force on the i-th wire feeding shaft during the current control cycle.

[0045] It should be noted that if the actual output torque of the motor is greater than the set tension braking torque in the current control cycle, it means that the i-th wire feeding shaft is in an abnormal working condition, and the original steady-state rotational resistance value is directly assigned to 0.

[0046] The second step is to determine the steady-state rotational resistance holding value of the i-th wire-feeding shaft in the current control cycle based on the original steady-state rotational resistance holding value of the i-th wire-feeding shaft.

[0047] To improve data stability and prevent numerical jumps caused by instantaneous mechanical vibration, the controller performs calculations... A first-order low-pass filter is performed, which mainly retains historical trends, integrates a small portion of current measurements, and adds non-negative limiting protection to obtain the final steady-state rotational drag retention value. The calculation formula is as follows: In the formula, This represents the steady-state rotational resistance value of the i-th wire-feeding shaft in the current control cycle, and max represents the function for finding the maximum value. This represents the filter coefficients, and their values ​​typically range from 0.05 to 0.2. This represents the steady-state rotational resistance value of the i-th wire feeding shaft in the previous control cycle of the current control cycle.

[0048] In the formula for calculating the steady-state rotational drag retention value, if If the value is less than 0, the steady-state rotational resistance of the i-th wire-feeding shaft in the current control cycle is forced to remain at 0 to ensure that the physical meaning of the resistance is positive.

[0049] It should be noted that the resistance register is refreshed in real time within the steady-state sampling range to reflect the latest mechanical damping level.

[0050] Furthermore, since the control system has not yet undergone a complete operation process at the moment of power-on or reset and restart, the historical data used to store the mechanical state in the system is in an unknown or null state. In order to ensure that the state variables called in subsequent calculation steps have a valid numerical basis and to prevent null references or calculation errors, the system first performs an initialization assignment operation.

[0051] Specifically, when the PLC controller detects the power-on reset signal, it iterates through all the wire-feeding shafts and assigns a preset initial resistance value to the steady-state rotational resistance holding value corresponding to each shaft. This value represents the basic frictional resistance level of a standard wire-feeding shaft under typical conditions. The initial resistance preset value is obtained during the factory commissioning phase by running the stranding machine at 50% of its rated speed under no-load conditions. The average output torque of each wire-feeding shaft at this time is recorded and set as the initial resistance preset value, stored in non-volatile memory. Furthermore, the initialization operation is performed only once at system startup, after which the real-time scanning control loop begins.

[0052] It should also be noted that during the steady-state sampling interval, the spindle acceleration command is less than or equal to the acceleration threshold, which can be physically considered as a state of uniform rotation. Since the angular acceleration is approximately zero, the component in the motor output torque used to overcome rotational inertia to generate acceleration theoretically does not exist. Therefore, the corresponding dynamic combined inertial load should be assigned a value of zero in physical logic. At this time, all the torque actually output by the motor is only used to balance the process tension and mechanical friction resistance.

[0053] When the sampling interval is determined to be transient, for each pay-off shaft of the stranding machine, the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle is determined based on the set tension braking torque, the actual output torque of the motor, and the steady-state rotational resistance holding value of the current cycle; wherein, the steady-state rotational resistance holding value of each pay-off shaft in the current control cycle is equal to the steady-state rotational resistance holding value in the previous control cycle.

[0054] During the transient sampling period, the motor output torque incorporates components of tension, friction, and inertia. Given that the acceleration and deceleration process of the stranding machine (typically several minutes) lasts much shorter than the equipment's thermal equilibrium time constant, it can be assumed that ambient temperature and frictional resistance do not change significantly within this short time. Therefore, the controller employs a strategy of locking in old values ​​as the calculation baseline.

[0055] Specifically, first, stop updating the resistance register, and set the steady-state rotational resistance value of each feed shaft in the current control cycle to be equal to the steady-state rotational resistance value in the previous control cycle, i.e. To maintain the value most recently measured in the steady-state range unchanged. Subsequently, using the steady-state rotational resistance hold value of each feed shaft in the current control cycle, the dynamic composite inertial load related only to acceleration and deceleration is separated from the total torque.

[0056] As an exemplary implementation, during the transient sampling interval, the dynamic composite inertial load of each pay-off axis in the current control cycle is determined, including: The first sub-step is to calculate the difference between the absolute value of the set tension braking torque of the same wire feeding shaft and the steady-state rotational resistance holding value, which is used as the motor's basic torque.

[0057] The second sub-step is to determine the absolute value of the difference between the absolute value of the actual output torque of the motor and the absolute value of the motor's basic torque as the dynamic comprehensive inertial load of the corresponding wire-laying shaft in the current control cycle.

[0058] Because the dynamic tension fluctuations of the wire are closely related to inertial acceleration during the transient range (usually positively correlated or close in phase), this embodiment uses the difference between the actual output torque and the equivalent steady-state torque characteristic as a comprehensive load characteristic that includes the rotational inertia component and the dynamic tension disturbance component. By monitoring this comprehensive load, the total torque margin of the system under extreme operating conditions can be evaluated more conservatively, thereby improving the sensitivity of overload protection.

[0059] As an example, taking the i-th wire-laying shaft as an example, the formula for calculating the dynamic comprehensive inertial load of the i-th wire-laying shaft in the current control cycle can be: In the formula, This represents the dynamic combined inertial load of the i-th wire feeding axis in the current control cycle. This represents the motor's base torque for the i-th wire feeding shaft in the current control cycle. This represents the function for finding the absolute value.

[0060] In the calculation formula for dynamic composite inertial load, the first step is to calculate the motor base torque required to maintain constant tension after deducting mechanical friction assistance, i.e. Then, calculate the difference between the actual output torque of the motor and the base torque. The absolute value of this difference can represent the extra electromagnetic torque that the motor has to exert to drive the pay-off reel to follow the acceleration change of the spindle, i.e., the dynamic comprehensive inertial load, which can be used to evaluate the load saturation of each pay-off shaft in the future.

[0061] Thus, this embodiment has determined the steady-state rotational resistance and dynamic combined inertial load of each pay-off shaft in the current control cycle.

[0062] S2, obtain the set of resistance characteristics consisting of the steady-state rotational resistance holding values ​​of all pay-off shafts, and determine the group median reference value of the standard resistance level under the current environmental conditions based on the set of resistance characteristics.

[0063] Here, the resistance characteristic set can reflect the distribution of mechanical friction resistance levels exhibited by all pay-off shafts in the system after removing tension and inertial components during the current control cycle, which can represent the central trend value of the influence of ambient temperature.

[0064] The group median reference value is derived from the physical coupling characteristics of the multi-axis winding machine operating in the same cage, at the same temperature, and at the same speed, and is used to characterize the common-mode resistance level under the current ambient temperature. Since all pay-off shafts are located within the same sealed cavity, the effect of ambient temperature changes on the viscosity of the lubricating grease in all bearings is highly consistent; however, the mechanical differences arising from variations in machining tolerances and wear levels among the shafts manifest as randomly distributed individual noise. Based on this physical law, this embodiment uses the set of resistance characteristics comprised of the steady-state rotational resistance values ​​of all pay-off shafts to determine the group median reference value.

[0065] As an exemplary implementation, a set of resistance characteristics consisting of the steady-state rotational resistance retention values ​​of all pay-off shafts is obtained, including: Within the current control cycle, all wire-laying shafts are synchronously updated or locked based on the unified operating condition judgment signal of the main traction motor. In order to evaluate the overall temperature drift trend of the system, the controller traverses the index of all wire-laying shafts, directly reads the current value in the steady-state rotational resistance holding value register corresponding to each wire-laying shaft, and places the extracted steady-state rotational resistance holding value in a temporary calculation array to construct the resistance feature set of the current control cycle.

[0066] As an exemplary implementation, the population median reference value of the standard resistance level under the current environmental conditions is determined based on the resistance characteristic set, such as... Figure 2 As shown, it includes: S201, based on the steady-state rotational resistance and angular velocity of the same wire-feeding shaft in the current control cycle, determine the unit damping coefficient of each wire-feeding shaft.

[0067] Different pay-off spools have different diameters, resulting in varying real-time angular velocities for each spool when the stranding machine operates at the same linear speed. Furthermore, mechanical friction resistance exhibits a positive velocity correlation, and directly calculating the median value for torque dimensions would introduce a systematic bias due to inconsistent rotational speeds. Therefore, it is necessary to sequentially arrange the unit damping coefficient determined by the steady-state rotational resistance and angular velocity to determine the group's median reference value.

[0068] In this embodiment, the ratio of the steady-state rotational resistance to the angular velocity of the same pay-off shaft in the current control cycle is calculated, and this ratio is determined as the unit damping coefficient of the corresponding pay-off shaft. When calculating the unit damping coefficient, a very small positive compensation term (e.g., 0.001) can be added to the denominator to ensure the numerical safety of the calculation.

[0069] It should be noted that by calculating the ratio of steady-state rotational resistance to angular velocity, the friction characteristics at different rotational speeds can be normalized to a unit damping coefficient of the same dimension. This eliminates dynamic interference caused by differences in roll diameter, enabling median statistics to accurately pinpoint the common characteristics of the group caused by ambient temperature or grease viscosity, thereby more accurately identifying individual mechanical wear deviations.

[0070] S202, using the unit damping coefficient of each wire-laying shaft, sorts all steady-state rotational resistance values ​​in the resistance characteristic set according to a preset order to obtain an ordered resistance sequence.

[0071] In this embodiment, quicksort or bubble sort algorithms are used to arrange all steady-state rotational drag values ​​in the drag feature set in ascending order of unit damping coefficient, generating an ordered drag sequence. The implementation process of quicksort or bubble sort algorithms is prior art and is not within the scope of this invention; therefore, it will not be described in detail here.

[0072] S203, determine the median of the resistance ordered sequence, and use the median as the benchmark value of the population median.

[0073] Since some individual pay-off shafts in the stranding machine may have extremely high resistance due to bearing damage or extremely low resistance due to seal detachment, if these abnormal outliers are included in the arithmetic mean calculation, they will significantly skew the benchmark value, resulting in a deviation in the evaluation of normal shafts. Therefore, this embodiment uses the median algorithm, which has a strong anti-interference ability against outliers, to determine the benchmark, that is, to determine the median benchmark value of the group.

[0074] Furthermore, the equivalent resistance characteristic actually combines pure mechanical friction resistance with the system's steady-state tension error. To avoid the influence of open-loop absolute error, this embodiment does not pursue precise measurement of absolute physical resistance. Instead, it calculates the group median reference value, filters out the overall basic offset including temperature drift and common-mode tension error, and extracts only the relative discrete deviation of each axis relative to the group for subsequent differential compensation.

[0075] In this embodiment, the center position value of the resistance ordered sequence is selected based on the parity of the total number of pay-off spools I, including: If the total number of casting spools I is odd, then the element at the very center of the resistance ordered sequence is directly selected as the output and recorded as the median reference value of the population. If the total number of spools I is even, the arithmetic mean of the two middle elements of the resistance ordered sequence is selected as the output, and denoted as the population median reference value.

[0076] It should be noted that the median statistical algorithm used in this embodiment exhibits significant robustness advantages: the median algorithm naturally possesses the characteristic of removing extreme values. In the constructed resistance feature set, the data of individual shafts with excessive resistance due to severe wear and overheating, or shafts with abnormally high resistance due to delayed cold start-up, are often distributed at both ends of the set (maximum or minimum value regions). The median calculation automatically ignores these extreme data at the tail of the distribution, avoiding their pulling on the baseline value, thereby ensuring the purity of the extracted results. By filtering out outliers at both ends, the calculated population median baseline value can be robustly locked at the resistance level of the vast majority of shafts under normal operating conditions, truly reflecting the common state of grease viscosity under the influence of ambient temperature during the current control cycle.

[0077] Therefore, the group median reference value can serve as a dynamic zero point, which will automatically drift as the ambient temperature rises (resistance decreases) or falls (resistance increases). In subsequent steps, it is only necessary to calculate the difference between each pay-off axis and this dynamic zero point to completely eliminate the influence of ambient temperature changes on control accuracy.

[0078] Thus, this embodiment has determined the population median reference value for the standard resistance level under the current environmental conditions.

[0079] S3. Based on the difference between the steady-state rotational resistance value of each wire-feeding shaft and the median reference value of the group, determine the differentiated compensation torque of each wire-feeding shaft in the current control cycle.

[0080] In multi-head wire feeding scenarios, ideally, the rotational resistance of all feed shafts should be completely uniform. However, in actual engineering, due to differences in bearing aging, lubrication conditions, shaft concentricity, slight differences in dynamic balance, differences in rotational inertia caused by different remaining diameters of the wire coils, or differences in wire winding tightness, the steady-state rotational resistance of each feed shaft will inevitably differ. If the same driving torque is applied to all shafts, the shaft with higher resistance will lag behind, while the shaft with lower resistance will lead. This tension inconsistency directly damages product quality. Therefore, to eliminate these differences, it is necessary to determine a differentiated compensation torque based on the difference between the steady-state rotational resistance of the same feed shaft and the median reference value of the group.

[0081] As an exemplary implementation, determining the differentiated compensation torque for each pay-off shaft in the current control cycle includes: The first step is to determine the individual wear resistance deviation value of each pay-off shaft in the current control cycle based on the difference between the steady-state rotational resistance value of the same pay-off shaft and the median reference value of the group.

[0082] Since the median reference value already includes common resistance components caused by ambient temperature, grease viscosity, and cage rotation speed, any deviation of the steady-state rotational resistance value of any pay-off spool from the median reference value can be attributed to differences in the mechanical condition of the corresponding individual pay-off spool, such as wear degree and assembly tightness. This embodiment calculates the individual wear resistance deviation value through simple subtraction.

[0083] It should be noted that the individual wear resistance deviation value The positive and negative signs have a clear physical orientation, as follows: when When the value is greater than the group reference, it indicates that the actual resistance of the i-th pay-off shaft is greater than the group reference. This usually means that the bearing of the i-th pay-off shaft is severely worn, poorly lubricated, or too tightly assembled, resulting in excessive auxiliary braking force provided by mechanical friction. The larger the individual wear resistance deviation value, the more severe the wear of the i-th pay-off shaft. when Time: This indicates that the actual resistance of the i-th wire-feeding shaft is less than the group reference, which usually means that the i-th wire-feeding shaft has problems such as the seal ring falling off, grease loss, or excessive mechanical fit clearance, resulting in insufficient auxiliary braking force provided by mechanical friction; when When the time is reached, it indicates that the mechanical state of the i-th wire-laying shaft is consistent with that of the group and is at a healthy level.

[0084] It should also be noted that the common mode resistance drift is overcome by the tension closed-loop regulator or the whole machine unified feedforward. This differentiated compensation torque is specifically designed to eliminate individual physical discrete deviations that cause uneven tension between shafts.

[0085] The second step is to set a resistance deviation threshold. Based on the comparison between the resistance deviation threshold and the individual wear resistance deviation value of each wire feeding shaft in the current control cycle, the differentiated compensation torque of each wire feeding shaft in the current control cycle is determined.

[0086] To eliminate the impact of individual mechanical wear differences on wire tension, the resistance deviation threshold of each pay-off shaft in the current control cycle needs to be converted into specific control commands, i.e., determining the differentiated compensation torque for each pay-off shaft in the current control cycle. Mechanical friction resistance plays an auxiliary role in the motor's braking function. Therefore, if the wear of a certain pay-off shaft is too large, the motor should reduce the output of electromagnetic braking force accordingly to maintain a constant total braking force; conversely, if the wear of that pay-off shaft is too small, the motor should increase the electromagnetic braking force.

[0087] In order to prevent frequent fine-tuning oscillations caused by measurement noise, this embodiment requires preprocessing by comparing the resistance deviation threshold and the individual wear resistance deviation value, and then calculating the differentiated compensation torque based on the preset compensation gain coefficient.

[0088] Specifically, when the absolute value of the individual wear resistance deviation of a certain wire-feeding shaft is less than the resistance deviation threshold, the differential compensation torque of the corresponding wire-feeding shaft in the current control cycle is set to zero; when the absolute value of the individual wear resistance deviation of a certain wire-feeding shaft is greater than or equal to the resistance deviation threshold, the differential compensation torque is determined based on the individual wear resistance deviation of the corresponding wire-feeding shaft and the preset compensation gain coefficient.

[0089] As an example, taking the i-th wire feeding shaft as an example, the expression for the differentiated compensation torque of the i-th wire feeding shaft in the current control cycle can be: In the formula, This represents the differential compensation torque of the i-th wire feeding axis in the current control cycle. This represents the individual wear resistance deviation value of the i-th wire feeding shaft in the current control cycle. This indicates the preset compensation gain coefficient. This indicates the resistance deviation threshold.

[0090] In the expression for differentiated compensation torque, the resistance deviation threshold is typically set to 1% to 3% of the rated torque to ignore minor random fluctuations; the recommended range for the compensation gain coefficient is [insert range here]. to The compensation gain coefficient can determine the depth of electrical compensation intervention, while retaining some physical damping helps to enhance the stability of the system.

[0091] It should be noted that after obtaining the differentiated compensation torque, an abnormal boundary fallback constraint strategy is introduced. An absolute safety compensation threshold is set. If the absolute value of the calculated differentiated compensation torque exceeds this safety threshold, it is determined that a serious mechanical failure has occurred on the current pay-off shaft (such as bearing jamming or wire breakage and loss of tension). In this case, the differentiated compensation torque output is forcibly cleared to zero, and a shutdown alarm signal is simultaneously triggered to the host computer. The absolute safety compensation threshold is typically set to 10% to 15% of the motor's rated output torque.

[0092] Thus, this embodiment has determined the differentiated compensation torque for each pay-off shaft in the current control cycle.

[0093] S4. Determine the maximum load percentage of the shaft based on the steady-state rotational resistance and dynamic combined inertial load of each wire-laying shaft in the current control cycle.

[0094] Determining the maximum load-percentage axis occupancy aims to construct a dynamic safety boundary assessment mechanism for multi-axis systems. Although the above steps have decoupled frictional resistance from inertia to extract independent features, the actual output capacity of the motor is limited by the total torque envelope. During dynamic wire feeding, the motor must simultaneously overcome steady-state rotational resistance (friction / wind resistance), accelerated inertial loss (dynamic response), and process tension load. For example, by superimposing the steady-state rotational resistance hold-up value and the dynamic comprehensive inertial load in real time, the system can accurately calculate the current instantaneous total load demand of each axis. Furthermore, by identifying the axis with the maximum load-percentage in the group control system and calculating its motor occupancy rate, the limit margin of the motor hardware under the worst operating conditions can be quantitatively assessed. Determining the maximum load-percentage axis occupancy rate can effectively prevent torque saturation, loss of synchronization, or even wire breakage accidents caused by transient overload of a single axis (such as rapid acceleration combined with high friction), ensuring the stable operation of the system within the dynamic limits.

[0095] As an example implementation, the maximum load percentage axis occupancy is determined, such as... Figure 3 As shown, it includes: S401, for each pay-off shaft, calculate the combined value of the steady-state rotational resistance holding value, dynamic comprehensive inertial load, and set tension braking torque, denoted as the total electromagnetic torque.

[0096] Here, total electromagnetic torque refers to the total electromagnetic torque that the motor needs to output in order to maintain the commanded motion state in the current control cycle, which is the theoretical maximum load requirement under the driving condition. It can be used to evaluate the safety margin under the worst operating conditions.

[0097] During the unwinding process, the motor must output torque simultaneously to offset the total demand of three physical components: (1) overcoming the tension load set by the process; (2) overcoming the rotational inertia load during acceleration and deceleration; and (3) superimposed mechanical friction damping. Although mechanical friction can play an auxiliary braking role in steady state, in dynamic processes, especially when changing the winding diameter or switching between acceleration and deceleration, the motor must ensure that it has sufficient electromagnetic output capability to cope with the most unfavorable superposition of these three factors.

[0098] As an example, the expression for the total electromagnetic torque of the i-th wire-feeding shaft in the current control cycle can be: In the formula, This represents the dynamic combined inertial load of the i-th wire feeding axis in the current control cycle. This represents the steady-state rotational resistance value of the i-th wire-feeding shaft during the current control cycle. This represents the set tension braking torque of the i-th wire feeding shaft in the current control cycle.

[0099] In the expression for total electromagnetic torque, the directions of the set tension braking torque and the dynamic combined inertial load may be opposite under different operating conditions (e.g., they are opposite during acceleration and in the same direction during deceleration). In order to evaluate the rated capacity utilization of the motor, it is necessary to consider the total current heat generation or magnetic flux saturation carried by the motor windings, which is determined by the magnitude of the output force (i.e., scalar modulus). Therefore, it is necessary to take the absolute value of the dynamic combined inertial load and the set tension braking torque to ensure that the system will not go out of control due to local torque saturation.

[0100] S402, based on the total electromagnetic torque and the torque parameters of the rated peak output of the introduced servo motor, determine the rated capacity occupancy rate of the wire-laying shaft motor.

[0101] Here, the rated peak output torque parameter of the servo motor is introduced as the physical upper limit of the motor's capacity. It is provided by the motor nameplate data and is an inherent constant of the hardware parameters, generally pre-stored in the controller. The motor's rated capacity utilization rate can characterize the current output load percentage of the motor.

[0102] In this embodiment, the rated capacity utilization rate of the pay-off shaft is determined by the ratio of the total electromagnetic torque to the rated peak output torque parameter of the servo motor. The formula for calculating the rated capacity utilization rate of the i-th pay-off shaft in the current control cycle is as follows: In the formula, This represents the rated capacity utilization rate of the motor for the i-th wire feeding shaft in the current control cycle. This represents the torque parameter of the rated peak output of the servo motor, i.e., the short-time peak torque of the servo motor.

[0103] S403: Select the maximum value among the rated capacity occupancy rates of all wire feeding shafts and determine the maximum load occupancy rate of the shaft.

[0104] In this embodiment, the rated capacity occupancy rate of the motors of all the wire feeding shafts is traversed and compared, and the maximum value is selected and recorded as the maximum load occupancy rate of the shaft. The corresponding wire feeding shaft index is locked, which is the node most prone to overload failure, and can be used to trigger the acceleration limiting logic.

[0105] Thus, this embodiment has obtained the maximum load ratio axis occupancy rate.

[0106] S5, by comparing the maximum load ratio axis occupancy rate with the preset safe load threshold, corrects the acceleration command of the system virtual spindle in the current cycle, and obtains the limited acceleration for the current control cycle.

[0107] By acquiring the acceleration constraint, a dynamic motion planning closed loop based on the weakest link constraint is constructed to prevent wire breakage accidents caused by overload of individual pay-off shafts. In a multi-axis coordinated stranding machine system, the ultimate acceleration and deceleration capability of the entire machine does not depend on the rated performance of the main traction motor, but is limited by the node with the smallest load margin among the group-controlled pay-off shafts. If the acceleration command of the main traction motor exceeds the physical following capability of the shortest shaft, the corresponding main pay-off shaft will be unable to maintain synchronous speed. Therefore, this embodiment uses the state of the shaft with the largest load proportion to dynamically adjust the motion planning of the entire machine, that is, to determine the acceleration constraint of the current control cycle.

[0108] In this embodiment, the preset safety load threshold can be set to 90%. The implementer can set it according to the specific safety control requirements of the equipment, and no specific limitation is made here.

[0109] As an exemplary implementation, obtaining the acceleration after the current control cycle limit includes: When the maximum load percentage axis occupancy exceeds a preset safe load threshold, the system determines that it is currently in a dynamic risk zone. At this point, the controller no longer executes the original aggressive acceleration command, but instead dynamically calculates a correction coefficient based on the degree to which the occupancy percentage exceeds the threshold. This coefficient reflects the deviation of the current system load from the safe boundary. By weighting the acceleration command of the system's virtual spindle with this correction coefficient, the system generates a compressed, constrained acceleration in real time. This mechanism ensures that the instantaneous torque demand of the bottleneck axis is forcibly pulled back within the safe threshold, preventing the risk of synchronization loss or disconnection at its source.

[0110] Specifically, if the maximum load percentage axis occupancy rate is greater than the preset safe load threshold, the acceleration command of the system virtual spindle in the current cycle is weighted using a correction coefficient determined by the preset safe load threshold and the maximum load percentage axis occupancy rate to obtain the limited acceleration for the current control cycle.

[0111] when This indicates that there are nodes in the system approaching overload, and scaling can be executed to reduce the spindle acceleration command after the current control cycle limit. As an example, the formula for calculating the acceleration after the current control cycle limit can be: In the formula, This indicates the acceleration after the current control cycle is limited. This indicates the acceleration command of the system's virtual spindle in the current cycle. This indicates the preset safe load threshold. This indicates the maximum load percentage of the axis during the current control cycle. This represents the correction factor for the current cycle.

[0112] When the maximum load percentage axis occupancy rate falls below the preset safe load threshold, the system is out of immediate danger. However, if it were to immediately and instantly return to the original high acceleration command, it could easily trigger mechanical shock or tension oscillations due to sudden command changes. Therefore, this embodiment introduces an acceleration recovery rate limiting strategy. In this mode, the controller performs limited amplitude processing on the original command, with core constraints including rate of change constraint and amplitude constraint. The rate of change constraint forcibly limits the change in acceleration relative to the previous cycle after the current cycle's limitation, ensuring it does not exceed the preset recovery threshold. This means the acceleration recovers gradually, rather than a step jump. The amplitude constraint ensures that the acceleration amplitude during the recovery process never exceeds the original command amplitude, preventing overshoot.

[0113] If the maximum load percentage axis occupancy rate is less than or equal to the preset safe load threshold, then based on the preset acceleration recovery rate limiting strategy, the acceleration command of the system virtual spindle in the current control cycle is limited to obtain the limited acceleration command.

[0114] The acceleration recovery rate limiting strategy is configured to: limit the change in the current cycle's post-limited acceleration command relative to the previous cycle's post-limited acceleration command to not exceed a preset recovery threshold, and limit the amplitude of the post-limited acceleration command to not exceed the amplitude of the system virtual spindle's acceleration command.

[0115] when When this occurs, it indicates that the current system load is within a safe range. To prevent the acceleration command from remaining at a limited low level indefinitely, the controller executes linear recovery logic. As an example, the formula for calculating the limited acceleration in the current control cycle can be: In the formula, min represents the function for finding the minimum value. This indicates the acceleration command following the limitation of the previous control cycle in the current control cycle. This represents the recovery threshold, which is typically set to 0.5% to 1% of the motor's maximum acceleration.

[0116] The acceleration command after limitation is sent to the control bus of the entire stranding machine in real time. All related drive shafts in the system (including but not limited to the main traction motor, take-up motor, wire laying motor, and strand rotation motor) strictly follow the acceleration command after limitation to perform synchronous motion planning based on the preset electronic gear ratio. This ensures that the speed ratio of each process link in the entire line remains unchanged during the spindle derating operation, eliminating the risk of the whole machine losing synchronization due to local limitation from the source.

[0117] It should be noted that the acceleration command determined by the dual-mode strategy in this embodiment not only realizes real-time overload cutoff based on the short-board effect, but also, more importantly, solves the problem of dynamic smooth transition after protection is released. It avoids mechanical jitter caused by frequent switching between protection and full-speed states, ensures the continuity and stability of tension in the stranding process, and significantly improves the robustness of the system and the quality of the finished product.

[0118] Thus, this embodiment obtains the acceleration after the current control cycle is limited.

[0119] S6. Based on the differentiated compensation torque of each pay-off axis in the current control cycle, and combined with the inertial feedforward torque determined based on the limited post-acceleration, determine the final execution torque command for each pay-off axis in the current control cycle.

[0120] Traditional inertial feedforward calculations are typically based directly on the original planned acceleration. However, in this embodiment, the input for calculating the inertial feedforward torque is strictly locked to the limited acceleration. This means that when the system triggers acceleration limiting due to overload on a certain axis, the inertial feedforward components of all axes will automatically and synchronously decrease. This mechanism ensures that the feedforward torque is strictly matched with the actual dynamic capability that the motor can provide, avoiding the driver from entering the saturation region due to excessive feedforward, thus preventing false alarms or overshoot from the source.

[0121] Differential compensation torque is a personalized correction made for the unique mechanical non-ideal characteristics of each pay-off spool. This component ensures that each spool can overcome its own specific resistance and maintain consistent tension, even during zero acceleration or constant speed phases.

[0122] The final torque command can be the vector sum of the differentiated compensation torque and the inertial feedforward torque. It should be noted that this synthesis strategy achieves a balance between global dynamic consistency and local static variability. It utilizes the limitation of post-acceleration to ensure the dynamic stability of the system under extreme conditions, while eliminating steady-state tension deviations between axes through differentiated compensation. The final command sent to the servo drive is an optimal torque solution that both meets safety boundary constraints and possesses high-precision tracking capabilities.

[0123] As an exemplary implementation, determining the final execution torque command for each pay-off shaft in the current control cycle includes: The first step is to obtain the set tension braking torque for each pay-off shaft in the current control cycle.

[0124] Setting the tension braking torque as the fundamental steady-state component for the final torque command is crucial for accurately calculating the basic reverse torque required to maintain constant wire tension based on the real-time coil diameter and target process tension. This embodiment incorporates the set tension braking torque into the final command, establishing a static reference for the tension closed loop. This ensures that the pay-off shaft provides a torque precisely balanced with the wire tension under all operating conditions—zero speed, constant speed, and variable speed—fundamentally eliminating the risk of loose or broken wire due to load mismatch. Simultaneously, it enables decoupling control, decoupling and superimposing the load resistance requirement for maintaining tension with the dynamic acceleration requirement to overcome inertia in the torque domain. This allows the system to independently respond to tension fluctuations caused by coil diameter changes and inertial impacts caused by speed changes, significantly improving control decoupling and response speed.

[0125] The second step involves performing data fusion processing on the differentiated compensation torque, set tension braking torque, and inertial feedforward torque of the same pay-off shaft to obtain a fusion value, and then determining the fusion value as the final execution torque command for the corresponding pay-off shaft in the current control cycle.

[0126] The inertial feedforward torque is equal to the product of the real-time rotational inertia of the same wire-laying shaft in the current control cycle and the acceleration after limitation.

[0127] As an example, the formula for calculating the final torque command of the i-th wire feeding shaft in the current control cycle can be: In the formula, This indicates the final torque command executed by the i-th wire feeding axis in the current control cycle. This represents the set tension braking torque of the i-th wire feeding shaft in the current control cycle. This represents the differential compensation torque of the i-th wire feeding axis in the current control cycle. This represents the inertial feedforward torque of the i-th wire feeding axis in the current control cycle.

[0128] For each pay-off shaft, the final torque command is determined by the algebraic superposition of its components. Under the definition of negative pay-off braking: the set tension braking torque, representing the basic braking force for maintaining process tension, is negative and serves as the basic electromagnetic braking force for maintaining process tension; the differential compensation torque is adjusted based on the positive or negative of individual wear deviations. If the pay-off shaft's bearing wear is high, the differential compensation torque is positive, and its superposition with the negative set tension braking torque reduces the amplitude of the final torque command, thus reducing motor output; if the pay-off shaft's damping is low, the differential compensation torque is negative, and its superposition with the negative set tension braking torque increases the amplitude of the final torque command, thus increasing motor output; the inertial feedforward torque is determined based on the product of real-time moment of inertia and the limited acceleration, providing the additional power required for acceleration and deceleration, ensuring the motor has torque to follow speed changes. Its sign is consistent with the limited acceleration; acceleration is positive compensation, and deceleration is negative compensation. During acceleration, the feedforward torque is positive, and it partially offsets the braking torque through algebraic superposition, making the pay-off reel easier to follow. During deceleration, the feedforward torque is negative, and it increases the braking amplitude through superposition, preventing the pay-off reel from impacting the material due to inertia. The amplitude of the final executed torque command is equal to the absolute value of the final executed torque command, and it must not exceed the rated torque of the motor.

[0129] After obtaining the final execution torque command for each pay-off axis in the current control cycle, the final execution torque command can be sent to each pay-off servo driver for execution via the fieldbus, thus achieving consistent control of wire tension under all working conditions.

[0130] Another embodiment of the present invention provides a stranding machine tension control system, including a processor and a memory, wherein the processor is used to process instructions stored in the memory to implement a stranding machine tension control method.

[0131] In this embodiment, the processor constructs a multi-axis synchronous data processing stream by calling and executing program instructions in the memory, thereby achieving real-time closed-loop control of the wire laying process.

[0132] The technical implementation of this system is highly consistent with the aforementioned control methods. Through the processor-based dynamic benchmark construction mechanism, the system achieves automatic filtering of environmental temperature drift interference and precise consistency correction of tension on each axis without the need for physical sensors. Simultaneously, by utilizing the processor's real-time monitoring of system load bottlenecks and dynamic acceleration constraint functions, the risk of torque saturation during dynamic processes is eliminated, significantly improving the operational stability and production safety of the stranding machine under high load and unbalanced conditions.

[0133] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for controlling the wire feeding tension of a stranding machine, characterized in that, Includes the following steps: Based on the operating characteristics of the current control cycle, determine the steady-state rotational resistance holding value and dynamic comprehensive inertial load of each wire-feeding shaft in the current control cycle; Obtain a set of resistance characteristics consisting of the steady-state rotational resistance holding values ​​of all pay-off shafts, and determine the group median reference value of the standard resistance level under the current environmental conditions based on the set of resistance characteristics. Based on the difference between the steady-state rotational resistance value of each pay-off shaft and the group median reference value, the differentiated compensation torque of each pay-off shaft in the current control cycle is determined; The maximum load percentage shaft occupancy rate is determined based on the steady-state rotational resistance holding value and the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle. Based on the comparison between the maximum load ratio axis occupancy rate and the preset safe load threshold, the acceleration command of the system virtual spindle in the current cycle is corrected to obtain the limited acceleration in the current control cycle. Based on the differentiated compensation torque of each pay-off axis in the current control cycle, and combined with the inertial feedforward torque determined based on the restricted post-acceleration, the final execution torque command for each pay-off axis in the current control cycle is determined.

2. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The determination of the steady-state rotational resistance and dynamic combined inertial load of each wire-feeding shaft in the current control cycle, based on the operating characteristics of the current control cycle, includes: Obtain the acceleration command and real-time speed of the main traction motor inside the stranding machine under the current control cycle; Based on the acceleration command and real-time rotation speed of the current control cycle, the operating condition of the stranding machine under the current control cycle is determined; wherein, the operating condition is a steady-state sampling interval or a transient sampling interval; When the steady-state sampling interval is determined, for each pay-off shaft of the stranding machine, the steady-state rotational resistance holding value of each pay-off shaft in the current control cycle is determined based on the difference between the set tension braking torque and the actual output torque of the motor in the current cycle; and the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle is assigned to zero. When the transient sampling interval is determined, for each pay-off shaft of the stranding machine, the dynamic comprehensive inertial load of each pay-off shaft in the current control cycle is determined based on the set tension braking torque, the actual output torque of the motor, and the steady-state rotational resistance holding value of the current cycle; wherein, the steady-state rotational resistance holding value of each pay-off shaft in the current control cycle is equal to the steady-state rotational resistance holding value in the previous control cycle.

3. The method for controlling the wire feeding tension of a stranding machine according to claim 2, characterized in that, The step of determining the operating condition of the stranding machine under the current control cycle based on the acceleration command and real-time rotation speed of the current control cycle includes: Set acceleration and rotation speed thresholds; When the absolute value of the acceleration command is less than or equal to the acceleration threshold, and the absolute value of the real-time rotation speed is greater than the rotation speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a steady-state sampling interval. When the absolute value of the acceleration command is greater than the acceleration threshold, or the absolute value of the real-time rotation speed is less than or equal to the rotation speed threshold, the operating condition of the stranding machine under the current control cycle is determined to be a transient sampling interval.

4. The method for controlling the wire feeding tension of a stranding machine according to claim 2, characterized in that, The determination of the dynamic comprehensive inertial load of each wire-feeding shaft in the current control cycle, based on the set tension braking torque, the actual output torque of the motor, and the steady-state rotational resistance holding value, includes: Calculate the difference between the absolute value of the set tension braking torque and the steady-state rotational resistance holding value of the same wire feeding shaft, and use it as the motor's basic torque; The absolute value of the difference between the actual output torque of the motor and the basic torque of the motor is determined as the dynamic comprehensive inertial load of the corresponding wire-laying shaft in the current control cycle.

5. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The step of determining the group median reference value of the standard resistance level under the current environmental conditions based on the resistance characteristic set includes: Based on the steady-state rotational resistance and angular velocity of the same wire-feeding shaft in the current control cycle, determine the unit damping coefficient of each wire-feeding shaft; Using the unit damping coefficient of each wire feeding shaft, all steady-state rotational resistance values ​​in the resistance characteristic set are sorted in a preset order to obtain an ordered resistance sequence; The median of the ordered resistance sequence is determined, and the median is used as the median benchmark value of the population.

6. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The step of determining the differentiated compensation torque for each pay-off shaft in the current control cycle based on the difference between the steady-state rotational resistance value of each pay-off shaft and the group median reference value includes: Based on the difference between the steady-state rotational resistance holding value of the same pay-off shaft and the group median reference value, the individual wear resistance deviation value of each pay-off shaft in the current control cycle is determined; Set a resistance deviation threshold. When the absolute value of the individual wear resistance deviation value of a certain wire-feeding shaft is less than the resistance deviation threshold, the differential compensation torque of the corresponding wire-feeding shaft in the current control cycle is assigned to zero. When the absolute value of the individual wear resistance deviation of a certain pay-off shaft is greater than or equal to the resistance deviation threshold, the differentiated compensation torque is determined based on the individual wear resistance deviation of the corresponding pay-off shaft and the preset compensation gain coefficient.

7. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The determination of the maximum load-percentage axis occupancy rate based on the steady-state rotational resistance holding value and the dynamic comprehensive inertial load of each pay-off axis in the current control cycle includes: For each pay-off shaft, calculate the combined value of the steady-state rotational resistance holding value, the dynamic comprehensive inertial load, and the set tension braking torque, and denote it as the total electromagnetic torque; Based on the total electromagnetic torque and the torque parameters of the rated peak output of the introduced servo motor, determine the rated capacity occupancy rate of the wire feeding shaft motor; Select the maximum value among all the motor rated capacity occupancy rates of the wire feeding shafts, and determine the maximum value as the maximum load occupancy rate of the shaft.

8. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The step of correcting the acceleration command of the system virtual spindle in the current cycle based on the comparison result between the maximum load percentage axis occupancy rate and the preset safe load threshold, to obtain the limited acceleration for the current control cycle, includes: If the maximum load percentage axis occupancy rate is greater than the preset safe load threshold, the acceleration command of the system virtual spindle in the current cycle is weighted using the correction coefficient determined by the preset safe load threshold and the maximum load percentage axis occupancy rate to obtain the limited acceleration for the current control cycle. If the maximum load percentage axis occupancy rate is less than or equal to the preset safe load threshold, then based on the preset acceleration recovery rate limiting strategy, the acceleration command of the system virtual spindle in the current control cycle is limited to obtain the limited acceleration command. The acceleration recovery rate limiting strategy is configured to: limit the change in the current cycle's post-limited acceleration command relative to the previous cycle's post-limited acceleration command to not exceed a preset recovery threshold, and ensure that the amplitude of the post-limited acceleration command is not greater than the amplitude of the system's virtual spindle's acceleration command.

9. The method for controlling the wire feeding tension of a stranding machine according to claim 1, characterized in that, The step of determining the final execution torque command for each pay-off axis in the current control cycle, based on the differentiated compensation torque for each pay-off axis in the current control cycle and combined with the inertial feedforward torque determined based on the limited post-acceleration, includes: Obtain the set tension braking torque for each wire feeding shaft in the current control cycle; The differential compensation torque, the set tension braking torque, and the inertial feedforward torque of the same pay-off shaft are fused to obtain a fused value, and the fused value is determined as the final execution torque command of the corresponding pay-off shaft in the current control cycle. The inertial feedforward torque is equal to the product of the real-time rotational inertia of the same wire-laying shaft in the current control cycle and the acceleration after limitation.

10. A stranding machine pay-off tension control system, characterized in that, It includes a processor and a memory, the processor being used to process instructions stored in the memory to implement a stranding machine tension control method as described in any one of claims 1-9.

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