Method and system for motion control of a servo press

Abstract

The application discloses a servo press motion control method and system, and relates to the technical field of servo press control. The method comprises the following steps: acquiring displacement, velocity, acceleration and jerk boundary parameters of stamping section start and end points, and constructing a seven-degree polynomial function; determining zero to third order low order term coefficients based on start point parameters; adopting an intelligent optimization algorithm to iteratively solve fourth to seventh order high order term coefficients to minimize a multi-objective fitness function; pre-storing the coefficient set in a controller register; in each interpolation period, the controller calls the coefficients to calculate displacement instructions and outputs, simultaneously collects actual slider displacement, calculates deviation and adjusts the low order term coefficients in the register in real time, which are used for instruction calculation at the next moment. By adjusting only the low order term coefficients and keeping the high order term unchanged in real-time control, the application effectively avoids curve oscillation caused by online adjustment of high order coefficients, and improves reliability.

Description

Technical Field

[0001] This application relates to the field of servo press control technology, and in particular to a servo press motion control method and system. Background Technology

[0002] Servo presses are key equipment in modern high-end manufacturing. The control precision and smoothness of their slide motion trajectory directly determine the quality of the stamped workpiece, the life of the die, and the stability of the equipment operation. Existing motion control methods for servo presses mostly employ cubic or quintic polynomials to plan the stamping curve. However, cubic polynomials can only guarantee continuous displacement and velocity, while acceleration exhibits abrupt changes; although quintic polynomials can guarantee continuous acceleration, their jerk curve still shows step changes. These abrupt changes in jerk can cause mechanical shock, leading to increased equipment vibration under high-speed stamping and severely affecting machining accuracy.

[0003] To address the aforementioned issues, a seventh-degree polynomial, with its eight configurable coefficients, can theoretically constrain the displacement, velocity, acceleration, and jerk at both the start and end points, thus achieving full parameter continuity. However, in practical engineering applications, seventh-degree polynomial curves are prone to the "Runge phenomenon," where even small fluctuations in the coefficients can cause severe oscillations at the curve's end, resulting in poor reliability. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a servo press motion control method. By adjusting only the lower-order term coefficients in real-time control while keeping the higher-order terms unchanged, it effectively avoids curve oscillations that may be caused by online adjustment of higher-order coefficients, thereby improving reliability. Correspondingly, a servo press motion control system is also provided to implement the aforementioned servo press motion control method.

[0005] The first technical solution adopted in this application is: providing a motion control method for a servo press, including: Obtain the displacement, velocity, acceleration, and boundary state parameters of the servo press at the start and end points of each segment of the stamping stroke; For each segment, a seventh-order polynomial function of displacement with respect to running time is constructed, the seventh-order polynomial function being defined by the coefficients of the zeroth to seventh-order terms; Based on the starting point parameter in the boundary state parameters, the coefficients of the lower-order terms in the seventh-degree polynomial function are determined, and the coefficients of the lower-order terms include the coefficients of the zeroth-order to third-order terms. Using an intelligent optimization algorithm, the boundary state parameters are used as search space constraints to iteratively optimize and solve for the coefficients of the higher-order terms of the seventh-degree polynomial function, so as to minimize the set multi-objective fitness function. The coefficients of the higher-order terms include the coefficients of the fourth-order to seventh-order terms. The coefficient set consisting of the lower-order term coefficients and the higher-order term coefficients corresponding to each segment is pre-stored in the register of the controller; Within each interpolation cycle, the controller calls the corresponding set of coefficients based on the running time of the current segment, calculates the displacement command value at the current moment, and outputs it to the servo drive mechanism; it collects the actual displacement of the slider, calculates the displacement deviation between the actual displacement and the displacement command value, and calculates the position compensation gain based on the displacement deviation within the current interpolation cycle. It uses the position compensation gain to adjust the low-order term coefficients in the register in real time, and calculates the displacement command value at the next moment based on the adjusted set of coefficients.

[0006] Furthermore, the correspondence logic between the lower-order term coefficients and the starting point parameters is as follows: the zero-order term coefficient is configured as the initial displacement value of the starting point; the first-order term coefficient is configured as the initial velocity value of the starting point; the second-order term coefficient is set according to the initial acceleration value of the starting point; and the third-order term coefficient is set according to the initial jerk value of the starting point.

[0007] Furthermore, the iterative optimization process for solving the higher-order term coefficients includes: setting the range of values ​​for the higher-order term coefficients; wherein, at the transition between adjacent segments, the calculated values ​​of displacement, velocity, acceleration, and jerk at the endpoint of the previous segment are constrained to be equal to the boundary state parameters at the starting point of the next segment.

[0008] Furthermore, the evaluation dimensions of the multi-objective fitness function include: The peak value of the absolute value of the acceleration during the segmented operation, the displacement deviation value at the end of the segment, and the total operation time of the segment; The evaluation dimensions are weighted and summed to obtain the objective function value.

[0009] Furthermore, the multi-objective fitness function is also configured with a constraint penalty term; the triggering logic for the constraint penalty term is as follows: During the iteration process, if the calculated velocity, acceleration, or jerk value at any moment within a segment exceeds the preset physical limit of the device, the objective function value is increased to eliminate coefficient solutions that do not meet the physical constraints.

[0010] Furthermore, the segmentation includes a rapid approach segment, a material contact segment, a forming segment, and a return segment; in the forming segment, by adjusting the search weights of the higher-order term coefficients, the coefficients of the fourth to seventh-order terms converge to zero during the iteration process, so as to convert the seventh-degree polynomial function into a linear displacement function.

[0011] Furthermore, the specific operation of the real-time adjustment is as follows: Keeping the values ​​of the higher-order term coefficients unchanged, the position compensation gain is calculated based on the displacement deviation; By using the position compensation gain to modify the first-order and second-order coefficients in the lower-order terms, the displacement command value generated in subsequent interpolation cycles is made to approach the actual displacement feedback.

[0012] Furthermore, the intelligent optimization algorithm employs a multi-stage collaborative search strategy: In the initial iteration phase, a global search algorithm is executed to locate potential regions of the coefficient set; In the later iteration stage, the algorithm is switched to a local optimization algorithm to improve the solution accuracy of the higher-order term coefficients.

[0013] Furthermore, the controller executes real-time safety monitoring logic: The actual displacement, actual velocity, actual acceleration, and actual jerk of the slider are compared with their respective preset thresholds in real time. When any parameter exceeds the corresponding preset threshold, the controller performs an action to reduce output power or apply emergency braking.

[0014] The second technical solution adopted in this application is: a servo press motion control system is provided, which can realize the servo press motion control method as described in any of the preceding claims, including: The parameter configuration unit is used to determine the boundary state parameters of the stamping segment; The optimization calculation unit is configured to iteratively optimize and solve for the coefficients of the higher-order terms of the seventh-degree polynomial function that minimizes the value of the multi-objective fitness function based on the boundary state parameters. A storage unit, including registers, is used to classify and store the set of coefficients corresponding to each segment; The execution control unit is configured to generate a displacement command based on the current running time and the set of coefficients in the register during the interpolation cycle, calculate the position compensation gain based on the displacement feedback signal to dynamically correct the low-order term coefficients in the register, and update the displacement command based on the corrected low-order term coefficients. Due to the adoption of the above technical solution, this application has at least one of the following beneficial effects compared with the prior art:

[0015] 1. By dividing the coefficients of the seventh-order polynomial into low-order and high-order terms and processing them separately: the low-order terms are directly determined by the starting boundary parameters, while the high-order terms are optimized offline using an intelligent optimization algorithm guided by a multi-objective fitness function; in real-time control, only the coefficients of the low-order terms are adjusted while the coefficients of the high-order terms remain unchanged, which effectively avoids the curve oscillation that may be caused by adjusting the high-order coefficients online and improves reliability.

[0016] 2. Using the complete eight coefficients of a seventh-order polynomial, eight boundary constraints are applied to the displacement, velocity, acceleration, and jerk at the start and end points of each segment, ensuring that the parameters of each order between adjacent segments are completely equal. This ensures that the displacement, velocity, acceleration, and jerk of the slider are continuous and without jumps throughout the entire movement, improving smoothness and stability.

[0017] 3. The smooth displacement command is calculated based on the pre-stored coefficients and used as feedforward. At the same time, the coefficients of the lower-order terms in the register are dynamically adjusted according to the actual displacement deviation while keeping the higher-order terms unchanged. While maintaining the smooth shape of the overall curve, the deviation between the actual trajectory and the command trajectory is quickly compensated, thus realizing high-precision closed-loop tracking control.

[0018] 4. Configure intelligent optimization algorithm, with a multi-objective fitness function that includes jerk peak, end displacement deviation and segmented running time as optimization target. By adjusting the weight of each target, it can adapt to different process requirements and improve applicability. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein: Figure 1 A schematic flowchart of a servo press motion control method provided in an embodiment of this application; Figure 2 This is a schematic diagram of the stamping stroke provided in an embodiment of this application; Figure 3 A servo press motion control system is provided in one embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. It is understood that the specific embodiments described herein are only for explaining this application and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all structures. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0021] The terms "first," "second," etc., used in this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] In existing motion control methods for servo presses, using cubic or quintic polynomial programming of the stamping curve can only guarantee the continuity of displacement, velocity, and even acceleration. However, abrupt changes in jerk can still occur, leading to significant mechanical shock and vibration during high-speed stamping. While using a seventh-order polynomial can theoretically achieve continuous jerk, the small fluctuations in the coefficients of its higher-order terms can easily trigger the Runge phenomenon, causing severe oscillations at the end of the curve. Furthermore, the traditional method is disconnected from the optimization solution and real-time control, making it impossible to effectively compensate for actual displacement deviations during operation. This results in insufficient trajectory tracking accuracy and makes it difficult to simultaneously meet the requirements of full-stroke smoothness, engineering reliability, and high-precision control.

[0024] In view of this, this application provides a motion control method for a servo press, which effectively avoids curve oscillations that may be caused by online adjustment of higher-order coefficients by adjusting only the lower-order coefficients in real-time control while keeping the higher-order coefficients unchanged. Figure 1 As shown, Figure 1 A flowchart illustrating a servo press motion control method provided in an embodiment of this application includes: Obtain the displacement, velocity, acceleration, and boundary state parameters of the servo press at the start and end points of each segment of the stamping stroke; For each segment, a seventh-order polynomial function of displacement with respect to running time is constructed, and the coefficients of the seventh-order polynomial function are defined by terms from zero to seventh order. Based on the starting point parameter in the boundary state parameters, determine the coefficients of the lower-order terms in the seventh-degree polynomial function. The coefficients of the lower-order terms include the coefficients of the zeroth-order to third-order terms. Using intelligent optimization algorithms, the boundary state parameters are used as search space constraints to iteratively optimize and solve for the coefficients of higher-order terms of the seventh-order polynomial function so as to minimize the set multi-objective fitness function. The higher-order terms include the coefficients of the fourth-order to seventh-order terms. The coefficient set consisting of the lower-order and higher-order coefficients corresponding to each segment is pre-stored in the controller's register; Within each interpolation cycle, the controller calls the corresponding coefficient set according to the running time of the current segment, calculates the displacement command value at the current moment, and outputs it to the servo drive mechanism; it collects the actual displacement of the slider, calculates the displacement deviation between the actual displacement and the displacement command value, and calculates the position compensation gain based on the displacement deviation within the current interpolation cycle. It uses the position compensation gain to adjust the low-order term coefficients in the register in real time, and calculates the displacement command value at the next moment based on the adjusted coefficient set.

[0025] The motion control method for servo presses is explained in detail below: First, segmentation and boundary parameter acquisition are performed. Based on the servo press's slide stroke, number of strokes, and stamping process requirements, the entire stamping stroke is divided into a rapid approach segment, a material contact segment, a forming segment, and a return segment. The start and end point parameters of each segment need to be physically verified to ensure that speed, displacement, and duration are matched. The specific setting principles for each segment are as follows: The rapid approach phase is the process of the slider descending from its upper end point to a preset position above the material. Its displacement range is determined by the slider stroke and the material's placement position, and its duration is allocated based on the number of strokes and the total cycle. The starting state is denoted as (…). , , , The final state is denoted as ( , , , ).

[0026] The material contact section is the process where the slider decelerates from a preset position above the material to the material contact position. Its displacement range is determined based on the material thickness and contact accuracy requirements, and its duration is set according to the deceleration smoothness requirements. The starting state is consistent with the ending state of the rapid approach section, and the ending state is denoted as (…). , , , ).

[0027] The forming section is the process of the slider pressing from the material contact position to the bottom dead center. Its displacement range is the distance from the material contact position to the bottom dead center. The duration is set according to the forming process requirements. The starting state is consistent with the ending state of the material contact section. The ending state is denoted as ( , , , ).

[0028] The return stroke is the process of the slider returning from the bottom dead center to the top end point. Its displacement range is the distance between the bottom dead center and the top end point. The duration is allocated according to the number of strokes and the total cycle. The starting state is denoted as ( , , , The final state is denoted as ( , , , ).

[0029] The sum of the durations of each segment is equal to the single stamping cycle of the servo press; for example... Figure 2 As shown, Figure 2 This is a schematic diagram of the stamping stroke provided in an embodiment of this application. In this embodiment, for a servo press with a slide stroke of 200mm and a stroke rate of 200 strokes / minute, a single stamping cycle is 0.3 seconds. The parameters for each segment are set as follows: the displacement range of the rapid approach segment is 0 to 195mm, and the duration is 0.12 seconds; the displacement range of the material contact segment is 195 to 198mm, and the duration is 0.03 seconds; the displacement range of the forming segment is 198 to 200mm, and the duration is 0.02 seconds; the displacement range of the return segment is 200 to 0mm, and the duration is 0.13 seconds.

[0030] Secondly, a seventh-order polynomial displacement curve model is constructed; for each segment, the following seventh-order polynomial is used as the displacement curve:

[0031]

[0032] in, Let be the slider displacement at time t, where t is the running time within the segment. to The coefficients are undetermined. The first, second, and third derivatives of the displacement curves are calculated sequentially to obtain the velocity curve, acceleration curve, and jerk curve:

[0033] .

[0034] .

[0035] .

[0036] The correspondence logic between lower-order term coefficients and starting parameters is as follows: the zero-order term coefficient is configured as the initial displacement value of the starting point; the first-order term coefficient is configured as the initial velocity value of the starting point; the second-order term coefficient is set according to the initial acceleration value of the starting point; the third-order term coefficient is set according to the initial jerk value of the starting point. For each segment, substituting the boundary conditions of the starting point (t=0) into the above curve, we can obtain: , , , That is, the coefficients of the lower-order terms are uniquely determined by the displacement, velocity, acceleration and jerk of the segment starting point; the coefficients of the lower-order terms can be directly calculated from the boundary parameters of the starting point without the need for optimization algorithms; this reduces the computational complexity and ensures that the motion state at the starting point accurately meets the process requirements.

[0037] The coefficients of higher-order terms are solved using an intelligent optimization algorithm; this embodiment uses the particle swarm optimization algorithm as an example for illustration; the algorithm parameters are set as follows: population size is 50, number of iterations is 100, inertia weight W=0.6, and individual learning factor... =1.5, group learning factor =1.5; to The range of values ​​for are respectively , , , .

[0038] The evaluation dimensions of a multi-objective fitness function include: The peak value of the absolute value of the acceleration during the segmented operation, the displacement deviation value at the end of the segment, and the total operation time of the segment; The evaluation dimensions are weighted and summed to obtain the objective function value.

[0039] The multi-objective fitness function is also configured with a constraint penalty term; the triggering logic for the constraint penalty term is as follows: During the iteration process, if the calculated velocity, acceleration, or jerk value at any moment within a segment exceeds the preset physical limit of the device, the objective function value is increased to eliminate coefficient solutions that do not meet the physical constraints.

[0040] The fitness function is defined as: .

[0041] This is the maximum value of the acceleration within the segment, used to assess the vibration level during the stamping process. The smaller the value, the smaller the impact on the equipment. The segment endpoint displacement deviation is the absolute value of the difference between the actual displacement at the segment endpoint and the preset endpoint displacement, used to evaluate stamping accuracy; T is the segment duration, and P is the penalty term. and The weighting coefficients can be set according to the segment type: for example, the forming segment takes... =0.6、 =0.4、 =0; The rapid approach segment and return segment are taken as... =0.7、 =0.2、 =0.1.

[0042] The penalty term P is set according to the following rule: during the optimization iteration process, for the coefficients of each set of candidate higher-order terms, calculate the velocity at all time points within the corresponding segment. acceleration and accelerometer .

[0043] If the speed at any moment exceeds the device's preset speed constraint Acceleration exceeds the device's preset acceleration constraint Or the acceleration exceeds the device's preset acceleration constraint. If the physical constraint is exceeded, a penalty term is triggered: P = 10000 × (exceedance value - constraint value); where the excess value is the maximum portion of the actual calculated value that exceeds the constraint, and the constraint value is the corresponding equipment physical limit; otherwise, P = 0. By setting a large penalty coefficient (such as 10000), the fitness value of any solution that violates the physical constraint increases dramatically, thus being naturally eliminated during the iteration process of the intelligent optimization algorithm, ensuring that the final output is a feasible solution that fully meets the equipment physical limit.

[0044] Taking a slider stroke of 200mm and a stroke rate of 200 strokes / min as an example, the preset constraints for the speed, acceleration, and jerk of each segment can be set as follows: Rapid approach segment: V≤2000mm / s, A≤50000mm / s², J≤50000mm / s³; Material contact segment: V≤1625mm / s, A≤50000mm / s², J≤50000mm / s³; Forming segment: V≤100mm / s, A≤500mm / s², J≤1000mm / s³; Return segment: V≤2000mm / s, A≤60000mm / s², J≤60000mm / s³. In other embodiments, the constraint values ​​can be selected separately, and no limitations are imposed on them.

[0045] The global optimum is output through iterative optimization using the particle swarm optimization algorithm. to Coefficients; then, the coefficients are stored. This results in a complete set of coefficients obtained from each segmented optimization. to The data are stored in the controller's registers, according to the segment number.

[0046] Finally, real-time control and correction are performed. The controller uses a 1-millisecond interrupt cycle. In the interrupt routine, it reads the running time t of the current segment, calls the coefficient set of the corresponding segment to calculate the displacement command value S(t), and sends it to the servo driver. Simultaneously, the controller collects the actual displacement of the slider through the displacement sensor, calculates the deviation from the command value, calculates the position compensation gain based on this deviation, and adjusts the lower-order term coefficients in the register in real time. to The controller calculates the displacement command for the next moment based on the adjusted coefficients. During segment switching, the controller checks whether the current running time has reached the segment duration. If it has, it resets t=0 and switches to the next segment, reading the corresponding coefficient set.

[0047] The iterative optimization process for finding the coefficients of higher-order terms includes: setting the range of values ​​for the coefficients of higher-order terms; in this embodiment, to The range of values ​​for are respectively , , , Right now , , , This range of values ​​can avoid numerical instability and Runge phenomenon caused by excessively large coefficients.

[0048] Specifically, at the transition between adjacent segments, the calculated values ​​of displacement, velocity, acceleration, and jerk at the end point of the previous segment are constrained to be equal to the boundary state parameters at the beginning point of the next segment; the specific constraint conditions are as follows: The end point of the previous segment (t= displacement ( The displacement is equal to the starting point of the next segment (t=0). (0); The end point of the previous segment (t= ) speed ( The velocity is equal to the velocity at the starting point of the next segment (t=0). (0); The end point of the previous segment (t= acceleration ( The acceleration is equal to the acceleration at the starting point of the next segment (t=0). (0); The end point of the previous segment (t= ) acceleration ( The acceleration is equal to the acceleration at the starting point of the next segment (t=0). (0).

[0049] The constraints are reflected in the fitness function of the intelligent optimization algorithm as the deviation from the endpoint. The penalty term; when the higher-order term coefficients obtained by optimization make the parameters of each order at the end of the previous segment inconsistent with the parameters of each order at the beginning of the next segment, the fitness function value will increase accordingly, thus eliminating the segment during the iteration process; the higher-order term coefficients obtained by final convergence can ensure that the S / V / A / J of each segment in the whole journey are completely continuous at the splicing point, without abrupt changes or shocks.

[0050] The process is divided into a rapid approach section, a material contact section, a forming section, and a return section. The forming section is the core process where the material undergoes plastic deformation, requiring the slider to move at a low and constant speed to ensure forming accuracy. To achieve this, the acceleration and jerk at the starting point of the forming section are first set to zero. Based on the aforementioned correspondence between the lower-order term coefficients and the starting point parameters, from... , It can be seen that, , .

[0051] In the shaping stage, by adjusting the search weights of the higher-order term coefficients, the coefficients of the fourth to seventh-order terms converge to zero during the iteration process, thus transforming the seventh-degree polynomial function into a linear displacement function. That is, in the intelligent optimization process of the shaping stage, by adjusting the parameter settings of the optimization algorithm (such as narrowing the search range of the higher-order term coefficients to a near-zero interval, or adding a penalty weight for the absolute value of the higher-order term coefficients in the fitness function), the optimization iteration naturally converges to zero. ≈0、 ≈0、 ≈0、 The solution is approximately 0; in this case, the seventh-degree polynomial degenerates into: .

[0052] Taking a specification with a slider stroke of 200mm and a stroke rate of 200 strokes / min as an example, the eight boundary constraints of the forming section are: at t=0, S=198mm, V=100mm / s, A=0mm / s², J=0mm / s³; at t=0.02s, S=200mm, V=100mm / s, A=0mm / s², J=0mm / s³. Substituting these values ​​directly yields the following results. =198、 =100、 =0、 =0, after optimization ~ ≈0, resulting in the seventh-degree polynomial of the forming segment: S(t)=100t+198, which meets the constraint conditions and has no Runge phenomenon.

[0053] The specific steps for real-time adjustment are as follows: Keeping the values ​​of higher-order term coefficients unchanged, the position compensation gain is calculated based on the displacement deviation; By using position compensation gain to modify the first-order and second-order coefficients in the lower-order terms, the displacement command value generated in subsequent interpolation cycles can be made closer to the actual displacement feedback.

[0054] During real-time control, the controller collects the actual displacement of the slider through a displacement sensor. Simultaneously, the theoretical displacement command at the current moment is calculated based on the seventh-degree polynomial. Calculate the displacement deviation e = .

[0055] Then, the controller calculates the position compensation gain K based on the displacement deviation e; the compensation gain can be calculated using proportional control, proportional-integral control, or other control strategies. For example, using simple proportional control: K = × e, where This is the proportionality coefficient.

[0056] The controller only modifies the coefficients of the lower-order terms in the registers, and mainly modifies the first-order terms. and second-order terms And the fourth to seventh order terms ~ Keep the optimized values ​​completely unchanged; Example of rule modification: , ;in and This is the corresponding compensation gain coefficient.

[0057] The modified lower-order coefficients are written back to the register, and in the next interpolation cycle, the controller will use the adjusted set of coefficients (the new set). , and unchanged , , , , , To calculate the displacement command. Because Directly affects the speed attribute. This directly affects the acceleration term, and this correction enables subsequent displacement commands to approximate the actual displacement feedback, achieving rapid convergence of the deviation. At the same time, since the higher-order terms remain unchanged, the overall smooth shape of the curve determined by the higher-order terms is completely preserved, and no oscillations are introduced due to real-time correction.

[0058] The intelligent optimization algorithm employs a multi-stage collaborative search strategy: In the initial iteration phase, a global search algorithm is executed to locate potential regions of the coefficient set; In the later iteration stage, the algorithm is switched to a local optimization algorithm to improve the solution accuracy of higher-order term coefficients.

[0059] By fusing two optimization algorithms with different characteristics, the shortcomings of a single algorithm, such as being prone to getting trapped in local optima or having insufficient convergence accuracy, are overcome. This embodiment uses the hybrid particle swarm optimization-gray wolf optimization algorithm as a specific implementation method, and the optimization steps are as follows:

[0060] (1) Parameter initialization: Set the population size to 50~60, the number of iterations to 100~120, the inertia weight W=0.6~0.7, and the individual learning factor. =1.5~1.8, group learning factor =1.5~1.8, the hierarchy coefficient A of the Grey Wolf algorithm decreases linearly from 2 to 0 with the number of iterations, and C is a random number between 0 and 2. ~ The range of values ​​for is as described above.

[0061] (2) Two-stage collaborative optimization: The first 50% of iterations are the global exploration stage, using the gray wolf optimization algorithm with a hierarchical guidance mechanism of α, β, and δ wolves. ~ A global search is performed in the high-dimensional coefficient space to eliminate solutions with coefficient oscillations that are prone to Runge phenomenon in advance; the last 50% of the iterations are the local refinement stage, and the particle swarm optimization algorithm is switched to. The global optimal solution obtained by the gray wolf optimization is used as the initial population to perform a local fine search and quickly converge to the optimal coefficient that satisfies the engineering constraints.

[0062] (3) Adaptive switching mechanism: Set a population diversity threshold. If the population diversity is lower than the threshold for 10 consecutive generations, switch to the particle swarm optimization stage in advance to balance optimization efficiency and solution accuracy.

[0063] (4) After the iteration converges, output the globally optimal value. ~ The coefficient combination, obtained by solving the boundary constraints ~ The coefficients are combined to form a complete seventh-degree polynomial.

[0064] The controller executes real-time safety monitoring logic: The actual displacement, actual velocity, actual acceleration, and actual jerk of the slider are compared with their respective preset thresholds in real time. When any parameter exceeds the corresponding preset threshold, the controller will reduce the output power or perform emergency braking.

[0065] The controller has a complete set of dynamic thresholds: the displacement threshold is set according to the mechanical stroke. In this embodiment, the displacement threshold is 0~200mm, the velocity threshold is set to 2000mm / s, the acceleration threshold is set to 60000mm / s², and the jerk threshold is set to 60000mm / s³.

[0066] During each interpolation cycle, the controller acquires the actual displacement through the displacement sensor and calculates the actual velocity, actual acceleration, and actual jerk sequentially. Each parameter is compared to its corresponding threshold: if the actual displacement exceeds the travel range, or if any of the velocity threshold, acceleration threshold, or jerk threshold exceeds the threshold, an anomaly protection is triggered.

[0067] The protective actions include: reducing output power, emergency braking, and simultaneously outputting alarm information and locking the equipment start function until the fault is cleared.

[0068] This application also provides a servo press motion control system, which can implement the servo press motion control method of any of the above embodiments, such as... Figure 3 As shown, Figure 3 A servo press motion control system provided in one embodiment of this application includes: The parameter configuration unit is used to determine the boundary state parameters of the stamping segment; The optimization calculation unit is configured to iteratively optimize and solve for the coefficients of the higher-order terms of the seventh-degree polynomial function that minimizes the value of the multi-objective fitness function based on the boundary state parameters. The storage unit, containing registers (not shown in the figure), is used to classify and store the set of coefficients corresponding to each segment; The execution control unit is configured to generate displacement instructions based on the current running time and the set of coefficients in the register during the interpolation cycle, calculate the position compensation gain based on the displacement feedback signal to dynamically correct the low-order term coefficients in the register, and update the displacement instructions based on the corrected low-order term coefficients.

[0069] In the several embodiments provided in this application, it should be understood that the disclosed methods and devices can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed.

[0070] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0071] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0072] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A motion control method for a servo press, characterized in that, include: Obtain the displacement, velocity, acceleration, and boundary state parameters of the servo press at the start and end points of each segment of the stamping stroke; For each segment, a seventh-order polynomial function of displacement with respect to running time is constructed, the seventh-order polynomial function being defined by the coefficients of the zeroth to seventh-order terms; Based on the starting point parameter in the boundary state parameters, the coefficients of the lower-order terms in the seventh-degree polynomial function are determined, and the coefficients of the lower-order terms include the coefficients of the zeroth-order to third-order terms. Using an intelligent optimization algorithm, the boundary state parameters are used as search space constraints to iteratively optimize and solve for the coefficients of the higher-order terms of the seventh-degree polynomial function, so as to minimize the set multi-objective fitness function. The coefficients of the higher-order terms include the coefficients of the fourth-order to seventh-order terms. The coefficient set consisting of the lower-order term coefficients and the higher-order term coefficients corresponding to each segment is pre-stored in the register of the controller; Within each interpolation cycle, the controller calls the corresponding set of coefficients based on the running time of the current segment, calculates the displacement command value at the current moment, and outputs it to the servo drive mechanism. The actual displacement of the slider is collected, the displacement deviation between the actual displacement and the displacement command value is calculated, and the position compensation gain is calculated based on the displacement deviation within the current interpolation cycle. The low-order term coefficients in the register are adjusted in real time using the position compensation gain, and the displacement command value at the next moment is calculated based on the adjusted coefficient set.

2. The servo press motion control method according to claim 1, characterized in that, The correspondence logic between the lower-order term coefficients and the starting point parameters is as follows: the zero-order term coefficient is configured as the initial displacement value of the starting point; the first-order term coefficient is configured as the initial velocity value of the starting point. The coefficients of the second-order term are set according to the initial value of the acceleration at the starting point; The coefficients of the third-order term are set based on the initial value of the jerk at the starting point.

3. The servo press motion control method according to claim 1, characterized in that, The iterative optimization process for solving the higher-order term coefficients includes: setting the range of values ​​for the higher-order term coefficients; wherein, at the transition between adjacent segments, the calculated values ​​of displacement, velocity, acceleration, and jerk at the endpoint of the previous segment are constrained to be equal to the boundary state parameters at the starting point of the next segment.

4. The servo press motion control method according to claim 1, characterized in that, The evaluation dimensions of the multi-objective fitness function include: The peak value of the absolute value of the acceleration during the segmented operation, the displacement deviation value at the end of the segment, and the total operation time of the segment; The evaluation dimensions are weighted and summed to obtain the objective function value.

5. The servo press motion control method according to claim 4, characterized in that, The multi-objective fitness function is also configured with a constraint penalty term; the triggering logic for the constraint penalty term is as follows: During the iteration process, if the calculated velocity, acceleration, or jerk value at any moment within a segment exceeds the preset physical limit of the device, the objective function value is increased to eliminate coefficient solutions that do not meet the physical constraints.

6. The servo press motion control method according to claim 1, characterized in that, The segmentation includes a rapid approach segment, a material contact segment, a forming segment, and a return segment; in the forming segment, by adjusting the search weights of the higher-order term coefficients, the coefficients of the fourth to seventh-order terms converge to zero during the iteration process, so as to convert the seventh-degree polynomial function into a linear displacement function.

7. The servo press motion control method according to claim 1, characterized in that, The specific operation of the real-time adjustment is as follows: Keeping the values ​​of the higher-order term coefficients unchanged, the position compensation gain is calculated based on the displacement deviation; By using the position compensation gain to modify the first-order and second-order coefficients in the lower-order terms, the displacement command value generated in subsequent interpolation cycles is made to approach the actual displacement feedback.

8. The servo press motion control method according to claim 1, characterized in that, The intelligent optimization algorithm employs a multi-stage collaborative search strategy: In the initial iteration phase, a global search algorithm is executed to locate potential regions of the coefficient set; In the later iteration stage, the algorithm is switched to a local optimization algorithm to improve the solution accuracy of the higher-order term coefficients.

9. The servo press motion control method according to claim 1, characterized in that, The controller executes real-time safety monitoring logic: The actual displacement, actual velocity, actual acceleration, and actual jerk of the slider are compared with their respective preset thresholds in real time. When any parameter exceeds the corresponding preset threshold, the controller performs an action to reduce output power or apply emergency braking.

10. A servo press motion control system, capable of implementing the servo press motion control method as described in any one of claims 1-9, characterized in that, include: The parameter configuration unit is used to determine the boundary state parameters of the stamping segment; The optimization calculation unit is configured to iteratively optimize and solve for the coefficients of the higher-order terms of the seventh-degree polynomial function that minimizes the value of the multi-objective fitness function based on the boundary state parameters. A storage unit, including registers, is used to classify and store the set of coefficients corresponding to each segment; The execution control unit is configured to generate a displacement command based on the current running time and the set of coefficients in the register during the interpolation cycle, calculate the position compensation gain based on the displacement feedback signal to dynamically correct the low-order term coefficients in the register, and update the displacement command based on the corrected low-order term coefficients.

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