System model construction method, construction device and computer storage medium

Abstract

The application provides a system model construction method and device and a computer storage medium. The method is applied to a computer device in a control system, and the control system comprises a control device, an output sensor and a controller. Firstly, frequency response data of the control device measured by the output sensor is obtained according to a preset time interval. Then, a closed-loop transfer function for describing a relationship between an input signal and an output signal of the control device on the computer device is obtained. Next, the closed-loop transfer function and the frequency response data are iterated. Finally, iteration values generated by adjacent iterations are compared. When a change amplitude of the iteration values generated by the adjacent iterations is less than a preset threshold, a latest to-be-constructed system model is taken as a constructed system model. In this way, the measured frequency response data and the closed-loop transfer function are iterated for multiple times, so that an accurate system model is constructed, and the stability and reliability of the control device are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of digital signal processing, in particular to a system model construction method and device and computer storage medium. BACKGROUND

[0002] In the construction of a system model of a control system in which a control device is located, a controller is usually configured on the control device to stabilize the device, and then the control device is excited by applying a disturbance signal, and a computer device identifies the transfer function and sensitivity function of the control system according to the measured signal to construct the system model. However, this method causes the accuracy of the constructed system model to decrease due to the difficulty in accurately identifying the sensitivity function in the low-frequency region of the control device, thereby affecting the stability and reliability of the control device in the control system. SUMMARY

[0003] Therefore, the present application aims to provide a system model construction method and device and computer storage medium, which use the obtained frequency response data and a closed-loop transfer function for describing the relationship between the input signal and the output signal of the control device to perform multiple iterations, thereby obtaining an accurate system model, improving the stability and reliability of the control device, and avoiding the situation of low accuracy of the constructed system model caused by the difficulty in accurately identifying the sensitivity function in the low-frequency region.

[0004] According to a first aspect of the present application, a system model construction method is provided, which is applied to a computer device in a control system, the control system further comprising a control device and an output sensor and a controller arranged on the control device, wherein the output sensor and the controller are connected to the computer device, and the method comprises:

[0005] obtaining frequency response data of the control device measured by the output sensor at a preset time interval;

[0006] obtaining a closed-loop transfer function for describing the relationship between the input signal and the output signal of the control device on the computer device, wherein the closed-loop transfer function comprises a transfer function of a system model to be constructed and a controller transfer function for describing the relationship between the input signal and the output signal of the controller on the computer device;

[0007] iterating the closed-loop transfer function and the frequency response data;

[0008] Compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value between two adjacent iterations is greater than or equal to a preset threshold, update the coefficients in the transfer function of the system model to be built. Repeat the above iteration process until the change in the iteration value between two adjacent iterations is less than the preset threshold. Then, end the iteration and take the latest system model to be built as the completed system model.

[0009] In one possible implementation of the first aspect, in the step of obtaining the closed-loop transfer function on the computer device used to describe the relationship between the input signal and the output signal of the control device:

[0010] The formula for the closed-loop transfer function is as follows:

[0011]

[0012] in, Represents the closed-loop transfer function. This represents the controller transfer function. This represents the transfer function of the system model to be constructed. This represents the frequency variable of the control device.

[0013] In one possible implementation of the first aspect, in the step of iterating the closed-loop transfer function with the frequency response data:

[0014] The formula for iteratively applying the closed-loop transfer function to the frequency response data is as follows:

[0015]

[0016] in, Represents the iteration value. This represents the frequency response data, where K represents the total amount of frequency response data measured by the output sensor. This represents the controller transfer function. This represents the transfer function of the system model to be constructed. This represents the frequency variable of the control device.

[0017] In one possible implementation of the first aspect, in the step of iterating the closed-loop transfer function with the frequency response data:

[0018] The formula for iteratively applying the closed-loop transfer function to the frequency response data is as follows:

[0019]

[0020] in, and Let represent the numerator and denominator coefficients of the controller transfer function, respectively. and Let these represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed, respectively. and Let represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed in the previous iteration, respectively. This represents the order of the numerator polynomial of the transfer function of the system model to be constructed. The value range is 0~M. This represents the order of the denominator polynomial of the transfer function of the system model to be constructed. The value range is 0 to N.

[0021] In one possible implementation of the first aspect, prior to the step of iterating the closed-loop transfer function with the frequency response data, the method includes:

[0022] Obtain the transfer function of the system model to be built as updated in the previous iteration.

[0023] In one possible implementation of the first aspect, the step of iterating the closed-loop transfer function with the frequency response data includes:

[0024] The closed-loop transfer function and the frequency response data are iterated using the least squares iterative method.

[0025] In one possible implementation of the first aspect, prior to the step of iterating the closed-loop transfer function with the frequency response data, the method further includes:

[0026] The order of the numerator polynomial and the order of the denominator polynomial in the transfer function of the system model to be constructed are pre-configured on the computer device.

[0027] The threshold for the iterative value is pre-configured on the computer device.

[0028] In one possible implementation of the first aspect, the coefficient of the highest term of the transfer function of the system model to be constructed in the denominator polynomial is 1.

[0029] According to a second aspect of this application, a system model building apparatus is provided, applied to a computer device in a control system. The control system further includes a control device and an output sensor and a controller disposed on the control device, wherein the output sensor and the controller are connected to the computer device. The apparatus includes:

[0030] The first acquisition module is used to acquire frequency response data of the control device measured by the output sensor at preset time intervals;

[0031] The second acquisition module is used to acquire the closed-loop transfer function on the computer device used to describe the relationship between the input signal and the output signal of the control device, wherein the closed-loop transfer function includes the transfer function of the system model to be constructed and the controller transfer function on the computer device used to describe the relationship between the input signal and the output signal of the controller;

[0032] An iteration module is used to iterate the closed-loop transfer function with the frequency response data;

[0033] The output module is used to compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value generated between two adjacent iterations is greater than or equal to a preset threshold, the coefficients in the transfer function of the system model to be built are updated, and the above iteration process is repeated until the change in the iteration value generated between two adjacent iterations is less than the preset threshold. Then the iteration ends, and the latest system model to be built is taken as the completed system model.

[0034] According to a third aspect of this application, a computer storage medium is provided, the computer storage medium storing an executable program, which, when executed by a computer device, implements the aforementioned system model construction method.

[0035] Based on any of the above aspects, embodiments of this application provide a system model construction method, construction device, and computer storage medium. This method is applied to computer equipment in a control system, which includes a control device, an output sensor, and a controller. First, frequency response data of the control device measured by the output sensor is acquired at preset time intervals. Next, a closed-loop transfer function on the computer device, describing the relationship between the input and output signals of the control device, is acquired. Then, the closed-loop transfer function and the frequency response data are iterated. Finally, the iteration values ​​generated by two adjacent iterations are compared. When the change in the iteration value between two adjacent iterations is less than a preset threshold, the latest system model to be constructed is taken as the completed system model. In the above method, the computer equipment uses the acquired frequency response data and the closed-loop transfer function used to describe the relationship between the input and output signals of the control device to perform multiple iterations, thereby obtaining an accurate system model, improving the stability and reliability of the control device, and avoiding the situation where the accuracy of the constructed system model is low due to the difficulty in accurately identifying the sensitivity function in the low-frequency region. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings required in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the interaction scenario of the control system provided in this embodiment;

[0038] Figure 2 This is a flowchart illustrating the steps of a system model construction method provided in this embodiment;

[0039] Figure 3 This is a schematic diagram of the functional modules of a system model building device provided in this embodiment.

[0040] Icons: 1-Control system, 10-Computer equipment, 20-Control device, 30-Output sensor, 40-Controller, 200-First acquisition module, 210-Second acquisition module, 220-Iteration module, 230-Output module. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0043] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0044] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0045] It should be noted that, where there is no conflict, different features in the embodiments of this application can be combined with each other.

[0046] In order to solve the technical problems mentioned in the background section, the inventors have innovatively designed the following technical solutions, and the specific implementation scheme of this application will be described in detail below with reference to the accompanying drawings.

[0047] Please see Figure 1 , Figure 1 This is a schematic diagram of the interaction scenario of the control system 1 provided in this embodiment. The control system 1 in this embodiment includes a computer device 10, a control device 20, and an output sensor 30 and a controller 40 disposed on the control device 20, wherein the output sensor 30 and the controller 40 are connected to the computer device 10. The output sensor 30 and the controller 40 can be connected to the computer device 10 via wireless communication (such as Bluetooth, WIFI, etc.). For example, the controller 40 applies control signals of different frequencies to the control device 20, and the output sensor 30 inputs the detected frequency response data of the control device 20 at different frequencies to the computer device 10. The computer device 10 uses the frequency response data and the closed-loop transfer function to perform multiple iterations to obtain a system model.

[0048] It is worth noting that the closed-loop transfer function is used to describe the relationship between the input and output signals of the control system 1. However, since the input and output of the control device 20 serve as the input and output of the entire control system 1, the closed-loop transfer function indirectly reflects the relationship between the input and output signals of the control device 20.

[0049] It is understood that the control system 1, where the control device 20 is located in this embodiment, is a system modeled using a linear time-invariant model. The system model construction method mentioned in this embodiment can be applied to any system modeled using a linear time-invariant model, such as a spring-mass-damping system, an inductor-resistor-capacitor system, etc. In addition, the system model structure modeled using a linear time-invariant model in this embodiment adopts a transfer function approach.

[0050] Understandable. Figure 1The control system 1 shown is only one possible example; in other possible embodiments, the control system 1 may also include only Figure 1 One or more of the components shown.

[0051] The following is combined with Figure 1 The application scenarios shown illustrate the system model construction method provided in this application. Please refer to... Figure 2 , Figure 2 This is a flowchart illustrating the steps of a system model construction method provided in this embodiment. The method is applied to... Figure 1 The computer device 10 in the control system 1 shown means that the method is executed by the computer device 10.

[0052] The detailed steps of the system model construction method performed by computer device 10 are described below:

[0053] Step S110: Acquire the frequency response data of the control device 20 measured by the output sensor 30 according to the preset time interval.

[0054] In this step, the output sensor 30 should measure the frequency response data of the control device 20 across the entire frequency range to ensure the accuracy of the subsequent system model construction. Frequency response data typically includes amplitude-frequency characteristics and phase-frequency characteristics.

[0055] In this embodiment, the output sensor 30 is used to measure the frequency response data generated when sweep signals of different frequencies are applied to the control device 20. The sweep signals can take the form of sine waves, pulses, etc.

[0056] Step S120: Obtain the closed-loop transfer function on the computer device 10 used to describe the relationship between the input signals and output signals of the control device 20. The closed-loop transfer function includes the transfer function of the system model to be constructed and the controller transfer function on the computer device 10 used to describe the relationship between the input signals and output signals of the controller 40.

[0057] In this embodiment, to ensure the stability of the control device, a controller 40 is introduced into the control system 1 to form a closed-loop control system. The input and output signals of this closed-loop control system are affected by the input and output signals of the controller 40. Therefore, the closed-loop transfer function used on the computer device 10 to describe the relationship between the input and output signals of the control device 20 is composed of the system model transfer function of the control system 1 and the controller transfer function of the controller 40.

[0058] It is worth noting that the controller transfer function is determined based on the design parameters of the controller 40 on the control device 20.

[0059] Step S130: Iterate the closed-loop transfer function and frequency response data.

[0060] Step S140: Compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value between two adjacent iterations is greater than or equal to a preset threshold, update the coefficients in the transfer function of the system model to be built. Repeat the above iteration process until the change in the iteration value between two adjacent iterations is less than the preset threshold. End the iteration and take the latest system model to be built as the completed system model.

[0061] In this step, the closed-loop transfer function and frequency response data are processed using the SK iteration method.

[0062] In related technologies, when the control system 1 itself is unstable, it is difficult to identify its open-loop model. Typically, a controller 40 is first configured on the control device 20 within the control system 1 to stabilize it. Then, an interference signal is applied to the output signal terminal of the controller 40 to excite the control device 20. The computer device 10 identifies the transfer function and sensitivity function of the control system 1 based on the signals measured by the output sensor 30 on the control device 20, thereby obtaining the system model. However, this construction method is difficult to identify because the sensitivity function is insensitive to interference signals in the low-frequency region of the control system 1, affecting the accuracy of the constructed system model.

[0063] However, in this embodiment, there is no need to identify the sensitivity function. The measured frequency response data is used as the actual measured value of the control device 20, and the closed-loop transfer function is used as the simulated predicted value of the control device 20. The difference between the two is minimized through multiple iterations. In each iteration, the coefficients in the transfer function of the system model to be constructed are continuously optimized until the change in the iteration value between two adjacent iterations is less than a preset threshold, at which point the iteration ends. Furthermore, in each iteration, the coefficients of the denominator polynomial are treated as constants, which are the coefficients of the numerator and denominator polynomials of the transfer function of the system model to be constructed in the previous iteration, and the coefficients of the known controller transfer function. This allows for faster identification of the coefficients in the transfer function of the system model to be constructed, thus achieving the construction of the system model. This improves the accuracy of the system model, which helps prevent unstable phenomena such as oscillation and divergence in the control device 20 during operation, ensuring the stability and reliability of the control system 1.

[0064] Furthermore, in step S120, the expression for the closed-loop transfer function is as follows:

[0065]

[0066] in, Represents the closed-loop transfer function. This represents the controller transfer function. This represents the transfer function of the system model to be constructed. This represents the frequency variable of the control device 20.

[0067] In this embodiment, In Represents the imaginary part in the field of complex numbers. This represents angular frequency. It can be replaced with 's'. For example, the transfer function of the system model to be constructed This indicates that the system model to be built is at a frequency of The frequency response data below.

[0068] Furthermore, in step S130, the expression formula for iteratively applying the closed-loop transfer function and frequency response data is as follows:

[0069]

[0070] in, Represents the iteration value. This represents the frequency response data, where K represents the total amount of frequency response data measured by the output sensor 30. This represents the controller transfer function. This represents the transfer function of the system model to be constructed. This represents the frequency variable of the control device 20.

[0071] In this step, the expression is presented as a non-convex optimization problem.

[0072] Furthermore, in step S130, the expression formula for iteratively applying the closed-loop transfer function and frequency response data is as follows:

[0073]

[0074] in, and Let represent the numerator and denominator coefficients of the controller transfer function, respectively. and Let these represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed, respectively. and Let represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed in the previous iteration, respectively. This represents the order of the numerator polynomial of the transfer function of the system model to be constructed. The value range is 0~M. This represents the order of the denominator polynomial of the transfer function of the system model to be constructed. The value range is 0 to N.

[0075] In this step, the expressed formula represents a convex optimization problem. This embodiment transforms a non-convex optimization problem into a convex optimization problem, thereby finding the coefficients in the transfer function of the system model to be constructed more efficiently, and thus realizing the construction of the system model.

[0076] Further, prior to step S130, the following steps are included:

[0077] Get the transfer function of the system model to be built that was updated in the previous iteration.

[0078] In this embodiment, the coefficients of the transfer function of the system model to be constructed in the previous iteration are used as the coefficients of the denominator polynomial in this iteration.

[0079] Furthermore, in step S130, the closed-loop transfer function and frequency response data are iterated using the least squares iterative method.

[0080] In this embodiment, the sum of squared errors between the closed-loop transfer function and the frequency response data is iterated. Based on the criterion of the least squares iteration method, the unknown coefficients of the system model function to be constructed in the closed-loop transfer function are adjusted so that the sum of squared errors (i.e., the iterative value) is minimized, thus obtaining the system model.

[0081] Furthermore, prior to step S130, the method further includes:

[0082] First, the order of the numerator polynomial and the order of the denominator polynomial in the transfer function of the system model to be built are pre-configured on the computer device 10.

[0083] In this step, the order of the numerator polynomial in the transfer function of the system model to be constructed ranges from 0 to M, and the order of the denominator polynomial ranges from 0 to N. Within this range, the order of the numerator and denominator polynomials is determined during iteration.

[0084] It is worth noting that the values ​​of the highest degree M of the numerator polynomial and the highest degree N of the denominator polynomial are not specifically limited here, and should be selected according to the actual situation.

[0085] Next, a threshold for the iterative values ​​is pre-configured on computer device 10.

[0086] In this embodiment, the threshold is the termination condition for the iteration, and its value is not specifically limited here, but needs to be selected according to the actual situation.

[0087] Furthermore, in this embodiment, the coefficient of the highest term in the denominator polynomial of the transfer function of the system model to be constructed is 1, thus preventing trivial solutions from occurring. A trivial solution is a solution in which all coefficients are 0.

[0088] Based on the same inventive concept, please refer to Figure 3 ,Figure 3 This is a schematic diagram of the functional modules of a system model building device provided in this embodiment. This embodiment can divide the system model building device into functional modules according to the above method embodiment. For example, each function can be divided into its own functional modules, or two or more functions can be integrated into one processing module. The integrated modules can be implemented in hardware or as software functional modules. It should be noted that the module division in this embodiment is illustrative and only represents one logical functional division; actual implementation may have other division methods. For example, in the case of dividing each functional module according to its own function... Figure 3 The system model building device shown is only a schematic diagram. The system model building device may include a first acquisition module 200, a second acquisition module 210, an iteration module 220, and an output module 230. The functions of each module of the system model building device will be described in detail below.

[0089] The first acquisition module 200 is used to acquire frequency response data of the control device 20 measured by the output sensor 30 at preset time intervals.

[0090] In this embodiment, the first acquisition module 200 can be used to execute... Figure 2 For a detailed description of the first acquisition module 200, see the description of step S110 shown.

[0091] The second acquisition module 210 is used to acquire the closed-loop transfer function on the computer device 10 used to describe the relationship between the input signal and the output signal of the control device 20. The closed-loop transfer function includes the transfer function of the system model to be constructed and the controller transfer function on the computer device 10 used to describe the relationship between the input signal and the output signal of the controller 40.

[0092] In this embodiment, the second acquisition module 210 can be used to perform... Figure 2 For a detailed description of the second acquisition module 210, see the description of step S120 shown.

[0093] Iteration module 220 is used to iterate the closed-loop transfer function and frequency response data;

[0094] In this embodiment, the iteration module 220 can be used to execute... Figure 2 For a detailed description of step S130, see the description of step S130.

[0095] Output module 230 is used to compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value generated between two adjacent iterations is greater than or equal to a preset threshold, the coefficients in the transfer function of the system model to be built are updated, and the above iteration process is repeated until the change in the iteration value generated between two adjacent iterations is less than the preset threshold. Then the iteration ends and the latest system model to be built is taken as the completed system model.

[0096] In this embodiment, the output module 230 can be used to execute... Figure 2 For a detailed description of the output module 230, see the description of step S140 shown.

[0097] Furthermore, embodiments of this application also provide a computer storage medium storing an executable program, which, when executed, can be used to implement the system model construction method provided in the above-described method embodiments.

[0098] Of course, the computer storage medium containing an executable program provided in the embodiments of this application is not limited to the above-described method operations, but can also perform related operations in the system model construction method provided in any embodiment of this application.

[0099] In summary, this application provides a system model construction method, construction device, and computer storage medium. The system model construction method is applied to computer equipment in a control system. The control system includes control equipment, output sensors, and controllers. First, frequency response data of the control equipment measured by the output sensors is acquired at preset time intervals. Next, the closed-loop transfer function on the computer equipment, used to describe the relationship between the input and output signals of the control system, is acquired. Then, the closed-loop transfer function and the frequency response data are iterated. Finally, the iteration values ​​generated by two adjacent iterations are compared. When the change in the iteration value between two adjacent iterations is less than a preset threshold, the latest system model to be constructed is taken as the completed system model. In the above method, the computer equipment uses the acquired frequency response data and the closed-loop transfer function used to describe the relationship between the input and output signals of the control equipment to perform multiple iterations, thereby obtaining an accurate system model, improving the stability and reliability of the control equipment, and avoiding the situation where the accuracy of the constructed system model is low due to the difficulty in accurately identifying the sensitivity function in the low-frequency region.

[0100] This application describes embodiments with reference to flowchart illustrations and / or block diagrams of methods, apparatus, and computer program products according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0101] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce a good effect.

[0102] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for constructing a system model, characterized in that, A computer device used in a control system, the control system further including a control device and an output sensor and a controller disposed on the control device, wherein the output sensor and the controller are connected to the computer device, the method comprising: The frequency response data of the control device measured by the output sensor is acquired at preset time intervals. Obtain the closed-loop transfer function on the computer device used to describe the relationship between the input signal and the output signal of the control device, wherein the closed-loop transfer function includes the transfer function of the system model to be constructed and the controller transfer function on the computer device used to describe the relationship between the input signal and the output signal of the controller; Iterate the closed-loop transfer function with the frequency response data; The formula for iteratively applying the closed-loop transfer function to the frequency response data is as follows: ； in, Represents the iteration value. This represents the frequency response data, where K represents the total amount of frequency response data measured by the output sensor. This represents the controller transfer function. This represents the transfer function of the system model to be constructed. This represents the frequency variable of the control equipment; Furthermore, this formula can be written as: ； in, and Let represent the numerator and denominator coefficients of the controller transfer function, respectively. and Let these represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed, respectively. and Let represent the numerator and denominator polynomial coefficients of the transfer function of the system model to be constructed in the previous iteration, respectively. This represents the order of the numerator polynomial of the transfer function of the system model to be constructed. The value range is 0~M. This represents the order of the denominator polynomial of the transfer function of the system model to be constructed. The value range is 0~N; Compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value between two adjacent iterations is greater than or equal to a preset threshold, update the coefficients in the transfer function of the system model to be built. Repeat the above iteration process until the change in the iteration value between two adjacent iterations is less than the preset threshold. Then, end the iteration and take the latest system model to be built as the completed system model.

2. The system model construction method as described in claim 1, characterized in that, Before the step of iterating the closed-loop transfer function with the frequency response data, the following steps are included: Obtain the transfer function of the system model to be built as updated in the previous iteration.

3. The system model construction method as described in claim 1, characterized in that, The step of iterating the closed-loop transfer function with the frequency response data includes: The closed-loop transfer function and the frequency response data are iterated using the least squares iterative method.

4. The system model construction method as described in claim 1, characterized in that, Prior to the step of iterating the closed-loop transfer function with the frequency response data, the method further includes: The order of the numerator polynomial and the order of the denominator polynomial in the transfer function of the system model to be constructed are pre-configured on the computer device. The threshold for the iterative value is pre-configured on the computer device.

5. The system model construction method according to any one of claims 1-4, characterized in that, The coefficient of the transfer function of the system model to be constructed in the denominator polynomial is 1.

6. A system model building apparatus based on the system model building method according to any one of claims 1-4, characterized in that, A computer device used in a control system, the control system further including a control device and an output sensor and a controller disposed on the control device, wherein the output sensor and the controller are connected to the computer device, the device comprising: The first acquisition module is used to acquire frequency response data of the control device measured by the output sensor at preset time intervals; The second acquisition module is used to acquire the closed-loop transfer function on the computer device used to describe the relationship between the input signal and the output signal of the control device, wherein the closed-loop transfer function includes the transfer function of the system model to be constructed and the controller transfer function on the computer device used to describe the relationship between the input signal and the output signal of the controller; An iteration module is used to iterate the closed-loop transfer function with the frequency response data; The output module is used to compare the iteration values ​​generated by two adjacent iterations. When the change in the iteration value generated between two adjacent iterations is greater than or equal to a preset threshold, the coefficients in the transfer function of the system model to be built are updated, and the above iteration process is repeated until the change in the iteration value generated between two adjacent iterations is less than the preset threshold. Then the iteration ends, and the latest system model to be built is taken as the completed system model.

7. A computer storage medium, characterized in that, The system contains an executable program, which, when executed by a computer device, implements the system model construction method according to any one of claims 1-4.

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