CN110376894B - Two-stage time-lag compensation method suitable for real-time hybrid test - Google Patents
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Abstract
A two-stage time-lag compensation method suitable for real-time hybrid test is provided. The introduction of time lag is difficult to avoid in a real-time mixing test, so that the precision and the reliability of a test result are influenced, and the conventional time lag compensation method has poor compensation effect in a nonlinear real-time mixing test and a high-frequency system real-time mixing test. The invention relates to a process for carrying out secondary fine compensation on residual time lag of a loading system by utilizing a self-adaptive time lag compensation method based on a discrete model after carrying out primary coarse compensation on the loading system. The invention can better compensate the loading control error caused by the uncertainty of the loading system and other parameters, effectively improves the precision and robustness of the loading system and ensures the reliability of real-time mixed test data.
Description
The technical field is as follows:
the invention particularly relates to a two-stage time-lag compensation method suitable for a real-time hybrid test.
Background art:
the real-time mixed test simulation analysis object is divided into a numerical substructure and a test substructure, and boundary conditions among the substructures are realized through a hydraulic servo loading system. The servo loading system accurately realizes boundary conditions among the substructures, and is a precondition for ensuring the reliability of test results. Because the servo loading system is a power system, time lag is inevitably introduced between measured displacement and command displacement, and the precision and the reliability of a test result are influenced. Therefore, skew compensation is one of the key techniques for real-time mixing experiments. The most widely used method of time lag compensation is the polynomial extrapolation method, which assumes that the system time lag is constant, although in practical real-time mixing experiments the time lag is often variable. Meanwhile, the loading system is not a pure delay system, and an amplitude error exists. The adaptive compensation method can better adapt to time lag variation, but the performance of the adaptive compensation method is often dependent on the estimation accuracy of the parameters. When the time lag variation is large, it is often difficult to guarantee high accuracy for parameter estimation. Therefore, the existing compensation method has certain limitations.
In real-time hybrid tests in the fields of machinery, aerospace, bridges and the like, in order to reproduce real dynamic response to the maximum extent, high-precision realization of expected displacement at a high frequency is often required. The conventional time lag compensation method has a good control effect on a linear real-time mixing test with a lower frequency, but when the method is applied to the real-time mixing test with a high-frequency loading command, high-frequency signals are amplified to different degrees, so that the control performance is poor, and even a divergence phenomenon occurs.
The invention content is as follows:
to solve the above mentioned problems in the background art, the present invention provides a two-stage skew compensation method suitable for real-time hybrid testing.
The technical scheme adopted by the invention is as follows:
a two-stage time lag compensation method suitable for a real-time hybrid test is a process of performing secondary fine compensation on residual time lag of a loading system by using a self-adaptive time lag compensation method based on a discrete model after performing primary coarse compensation on the loading system.
As a preferable scheme: the process of performing the primary coarse compensation and the secondary fine compensation on the loading system comprises the following steps:
first-stage rough compensation: obtaining system time lag according to the early off-line test, and roughly compensating the system time lag by utilizing a polynomial extrapolation method;
secondary fine compensation: and further compensating the time lag of the loading system according to a self-adaptive time lag compensation method based on the discrete model, firstly estimating parameters of the discrete model by matching the test expected displacement and the test actual displacement, and then compensating the residual time lag of the loading system by using a corresponding compensator.
As a preferable scheme: when the polynomial extrapolation method is a third-order polynomial extrapolation method, the ith command displacement y of the loading system is obtained according to the calculation formula of the third-order polynomial extrapolation method c,i The specific calculation formula is as follows:
in the above formula, y ac,i Inputting displacement for the ith step of the polynomial extrapolation control module; η is a first time parameter.
As a preferable scheme: the first time parameter eta is the ratio of the time lag tau of the loading system to the time step length delta t of the data point, and the calculation formula of the first time parameter eta is as follows:
in the above formula, the time lag τ of the loading system is calculated by an off-line test part, and Δ t is the time step of the data point.
As a preferable scheme: in the process of secondary fine compensation calculation, a self-adaptive compensation method based on a discrete model is used for calculation, and when the parameter model is a three-parameter model, the i-th step input displacement y of the polynomial extrapolation method control module is calculated through the three-parameter model ac，i The process of (2) is as follows:
y ac，i ＝θ a，1 y m，i +θ a，2 y m，i-1 +θ a，3 y m，i-2
in the above formula, θ a,1 、θ a,2 And theta a,3 Three parameters are adopted; y is m,i 、y m,i-1 And y m,i-2 And (4) measuring the displacement of the test piece in the ith step, the ith-1 step and the ith-2 step.
As a preferable scheme: estimating discrete model parameters on line by using a recursive least square method with forgetting factors, wherein the calculation formula is as follows:
ψ i ＝[y m，i y m，i-1 ym，i-2 ]
in the above formula, the first and second carbon atoms are,
is the parameter estimate of step i,/>>
Is the parameter estimation value of the step i-1, rho is a forgetting factor, y m,i The measured displacement of the test piece in the step i is obtained; psi i Is and>
respectively, the measured displacement vector and the transpose thereof, and P is a covariance matrix.
As a preferable scheme: in the secondary fine compensation calculation process, the calculation formula of the fine compensation is as follows:
in the above formula, the first and second carbon atoms are,
is theta a,1 Is evaluated by the evaluation unit>
Is theta a,2 Is evaluated by the evaluation unit>
Is theta a,3 Estimated value of y a,i To load the desired displacement of step i of the system, y a,i-1 To load the desired displacement of step i-1 of the system, y a,i-2 The expected displacement of the i-2 step of the system is loaded.
As a preferable scheme: the polynomial extrapolation method is replaced by an inverse model method, before the first-stage time lag compensation is completed by using the inverse model method, a system model is identified, and when the identification system model is a second-order transfer function model, a calculation formula of the second-order transfer function model is as follows:
in the above formula, s, ω, and ζ represent the laplace variable, the equivalent circular frequency, and the equivalent damping ratio, respectively.
As a preferable scheme: the parameters of the first-stage rough compensation operation are not required to be updated online, and the parameters of the second-stage fine compensation operation are required to be identified and updated online.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a two-stage self-adaptive time lag compensation method. The compensation effect of the invention is superior to the conventional time lag compensation method and the self-adaptive time lag compensation method, the first-stage rough compensation of the invention adopts a polynomial extrapolation method or an inverse model or other conventional time lag compensation methods to carry out rough compensation on the time lag of a loading system; and the secondary fine compensation adopts a self-adaptive compensation method based on a discrete system model to perform fine compensation on the residual time lag. Tests show that the compensation performance of the invention is excellent.
2. The two-stage self-adaptive time-lag compensation method adopts a three-order polynomial extrapolation method with better effect as a first-stage compensation method, and the second-stage self-adaptive time-lag compensation method makes up the defect that the polynomial extrapolation method has poorer compensation performance for a variable time-lag system; and the polynomial extrapolation method realizes most of time lag compensation requirements, greatly reduces the difficulty of self-adaptive time lag compensation, and can realize fineness at the second level. The inverse model can also be used as a first-stage compensation method, and high-precision compensation of the high-frequency signal is realized by combining with a self-adaptive time lag compensation method.
3. The invention overcomes the defect that the conventional time lag compensation method has non-ideal control effect on the variable time lag system, and simultaneously reduces the time lag required to be compensated, reduces the compensation difficulty and improves the compensation precision. Therefore, the invention can well compensate the loading control error caused by the uncertainty of the loading system and other parameters, effectively improve the precision and robustness of the control system and ensure the reliability of test data.
4. The invention can combine the inverse model compensation method and the self-adaptive time lag compensation method to complete the time lag compensation of the high-frequency signal. The inverse model is an inverse model of the loading system model, is connected with the control object in series, and is equivalent to the controller model and the control object model to offset each other from the theoretical angle, so that the effect of time-lag compensation, namely the first-stage time-lag compensation, is achieved. And the second stage adopts a self-adaptive time lag compensation method to compensate the residual time lag controlled by the first stage inverse model, thereby greatly improving the robustness, adaptability and precision of time lag compensation.
5. The invention has wide application range, and is particularly suitable for time lag compensation of nonlinear real-time hybrid tests and high-frequency system real-time hybrid tests. The invention relates to various fields, in particular to the fields of civil engineering, traffic, bridges, machinery, aerospace and other fields related to time lag compensation.
Description of the drawings:
for ease of illustration, the present invention is described in detail in the following detailed description and accompanying drawings, which illustrate the basic principles of the present invention method for performing a real-time mixing test when the magnetorheological damper is used as a test piece for the real-time mixing test.
FIG. 1 is a schematic diagram illustrating a real-time mixing test performed when a test piece is a magnetorheological damper according to the present invention;
FIG. 2 is a schematic block diagram of a first process of the present invention in which a polynomial extrapolation method is used to roughly compensate for loading system skew;
FIG. 3 is a schematic block diagram of a second process of the present invention for roughly compensating for loading system skew using an inverse model method;
FIG. 4 is a schematic flow diagram of a real-time mixing test using the magnetorheological damper of the method of FIG. 2;
FIG. 5 is a schematic flow diagram of a real-time mixing test using the magnetorheological damper of the method of FIG. 3.
The specific implementation mode is as follows:
in order that the objects, aspects and advantages of the invention will become more apparent, the invention will be described by way of example only, and with reference to the accompanying drawings. It is to be understood that this description is made only by way of example and not as a limitation on the scope of the invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.
It should be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and/or processing steps closely related to the scheme according to the present invention are shown in the drawings, and other details not so relevant to the present invention are omitted.
The first embodiment is as follows: the specific process of the embodiment is a process of performing secondary fine compensation on the residual time lag of the loading system by using a self-adaptive time lag compensation method based on a discrete model after performing primary coarse compensation on the loading system.
Further, the operation process of the first-stage rough compensation is to obtain system time lag according to a previous off-line test and roughly compensate the system time lag by utilizing a polynomial extrapolation method; the first stage of coarse compensation is a one-time operation.
Further, two-stage fine compensation: and further compensating the time lag of the loading system according to a self-adaptive time lag compensation method based on the discrete model, firstly estimating parameters of the discrete model by matching the test expected displacement and the test actual displacement, and then compensating the residual time lag of the loading system by using a corresponding compensator. The secondary fine compensation is a repeated compensation process for many times, and the whole test process is run through, so that a timely and effective time lag compensation process is realized.
Further, when the polynomial extrapolation method is a third-order polynomial extrapolation method, the ith command displacement y of the loading system is obtained according to the calculation formula of the third-order polynomial extrapolation method c,i The specific calculation formula is as follows:
in the above formula, y ac,i Inputting displacement for the ith step of the polynomial extrapolation control module, and calculating by using a related calculation formula; eta is a first time parameter and needs to be calculated by a correlation calculation formula.
Further, the first time parameter η is a ratio of the time lag τ of the loading system to the time step Δ t of the data point, and the calculation formula of the first time parameter η is as follows:
in the above formula, the time lag τ of the loading system is calculated by an off-line test part, and Δ t is the time step of the data point. The data point time step may be different from the integration step, and Δ t is calculated by the computer-related program during the experiment.
Further, the off-line test part of the calculation process is as follows:
the method comprises the following steps: building test equipment and establishing a numerical substructure and a test piece model;
step two: calculating the command displacement of the test piece in the early off-line test;
step three: sending the command displacement to a loading system to be used as an actuator for loading;
step four: measuring the actual measurement displacement of the off-line test specimen, calculating the time lag tau of the system, and taking the initial value theta of the system model parameter 0 。
Furthermore, in the process of secondary fine compensation calculation, a self-adaptive compensation method based on a discrete model is used for calculation, and when the parameter model is a three-parameter model, the i-th step input displacement y of the polynomial extrapolation method control module is calculated through the three-parameter model ac,i The calculation formula of (c) is:
y ac，i ＝θ a，1 y m，i +θ a，2 y m，i-1 +θ a，3 y m，i-2
in the above formula, θ a,1 、θ a,2 And theta a,3 Three parameters are adopted; y is m,i 、y m,i-1 y m,i-2 And (4) measuring the displacement of the test piece in the steps i, i-1 and i-2. Theta.theta. a,1 、θ a,2 And theta a,3 The identification method needs to be adopted for online identification and updating, and detailed description is given later. y is m,i 、y m,i-1 And y m,i-2 The displacement of the actuator and the test piece which actually occur needs to be measured by a sensor.
Further, a recursive least square method with forgetting factors is used for estimating discrete model parameters on line, and the calculation formula is as follows:
ψ i ＝[y m，i y m，i-1 y m，i-2 ]
in the above-mentioned formula, the compound has the following structure,
is an estimate of the parameter in step i->
Is the parameter estimation value of the step i-1, rho is a forgetting factor, y m,i The measured displacement of the test piece in the step i is obtained; psi i Is and>
respectively the measured displacement vector and its transpose, P i Is a covariance matrix. In the above formula, y m,i 、y m,i-1 y m,i-2 The measurement is needed to obtain; rho needs to be specified before the test, and is generally more than 0.9 and less than or equal to 1; />
And P i-1 The current time is a known quantity as a result of the last calculation step; in a first step, is selected>
And P 0 The off-line data can be used to obtain the data by performing the least square calculation once.
Further, in the second-level fine compensation calculation process, the calculation formula of the fine compensation is as follows:
in the above formula, the first and second carbon atoms are,
is theta a,1 In combination with an evaluation value of>
Is theta a,2 Is evaluated by the evaluation unit>
Is theta a,3 Estimated value of y a,i To load the desired displacement of step i of the system, y a,i-1 To load the desired displacement of step i-1 of the system, y a,i-2 The expected displacement of the i-2 step of the system is loaded. In the above formula, the parameter estimation value is provided by the above recursive least square algorithm, and the expected displacement is obtained by solving the numerical substructure response by the stepwise integral algorithm.
The second embodiment is as follows: this embodiment is a further limitation of the first embodiment, and y in this embodiment ac,i Inputting displacement for the ith step of the polynomial extrapolation control module; y is ac,i The calculation process is obtained by sequentially calculating the following formulas:
ψ i ＝[y m，i y m，i-1 y m，i-2 ]
y ac，i ＝θ a，1 y m，i +θ a，2 y m，i-1 +θ a，3 y m，i-2
wherein the content of the first and second substances,
is theta a，1 In combination with an evaluation value of>
Is theta a，2 In combination with an evaluation value of>
Is theta a，3 Estimated value of (a), y a，i To load the desired displacement of step i of the system, y a，i-1 To load the expected displacement of step i-1 of the system, y a，i-2 To load the desired displacement for step i-2 of the system. />
Is an estimate of the parameter in step i->
Is the parameter estimation value of the step i-1, wherein rho is a forgetting factor and y m，i The measured displacement of the test piece in the step i is obtained; psi i Is and>
respectively, the measured displacement vector and the transpose thereof, and P is a covariance matrix. />
θ a，2 And theta a，3 Three parameters are adopted; y is m，i 、y m，i-1 And y m，i-2 And (4) measuring the displacement of the test piece in the ith step, the ith-1 step and the ith-2 step.
The calculation processes are calculated under the control of computer-related programs, and the related programs are all existing programs. Obtaining a polynomial by calculationStep i input displacement y of extrapolation method control module ac，i Then, a first time parameter η is obtained by calculation according to a formula, wherein the calculation formula of the first time parameter η is as follows:
then the ith step input displacement y of the polynomial extrapolation control module obtained by calculation is input ac，i Substituting the first time parameter eta into the following formula to calculate the ith step command displacement y of the loading system c，i The specific calculation formula is as follows:
the third concrete implementation mode: the present invention further defines the first or second embodiment, and includes an off-line testing part and an on-line testing part, wherein the off-line testing part is used for measuring the actual measurement displacement, calculating the system time lag τ, and determining the initial parameter value, and the off-line testing part is performed before the first-stage coarse compensation, and provides the actual measurement displacement, the system time lag τ and the initial parameter value for the first-stage coarse compensation. The on-line test part is carried out in a primary fine compensation process, and the on-line test part is a cyclic operation process.
When the polynomial extrapolation method is used for roughly compensating the time lag of the loading system, the specific processes of the off-line test part and the on-line test part are as follows:
the operation process of the off-line test part is as follows:
firstly, establishing a numerical value substructure and a test piece model, then calculating the command displacement of an off-line test, sending the command displacement to a loading system for loading, measuring the actual measurement displacement, calculating the time lag tau of the system, and determining the initial value of the parameter.
And after the off-line test part is finished, the operation of the on-line test part is carried out, and the specific operation process is as follows:
firstly, calculating the expected displacement y of the test piece a Then adopting a least square method with a forgetting factorUpdating system model parameters on line and calculating self-adaptive time-lag compensation output displacement y ac Performing polynomial extrapolation compensation to obtain the command displacement y of the controlled object c Shift the command by y c Sending the measured displacement to a loading system, loading the test piece, and measuring the measured displacement and the counter force f of the test piece e Directly returning to the step of calculating the expected displacement y of the test piece according to t ← t + delta t a And the process is repeated circularly throughout the whole real-time mixing test.
In the present embodiment, all the systems mentioned in the above process are loading systems.
The fourth concrete implementation mode is as follows: the present embodiment is further limited by the first or second embodiment, and the present invention includes an offline testing part and an online testing part, wherein the offline testing part is used for identifying the system model and determining the initial values of the parameters of the system model, and the offline testing part is performed before the first-stage rough compensation and provides the identification system model for the first-stage rough compensation to determine the initial values of the parameters of the system model. The on-line test part is carried out in a primary fine compensation process, and the on-line test part is a cyclic operation process.
When the time lag of the loading system is roughly compensated by using an inverse model method, the specific processes of the off-line test part and the on-line test part are as follows:
the operation process of the off-line test part is as follows:
firstly, establishing a numerical value substructure and a test piece model, then calculating command displacement of an off-line test, sending the command displacement to a loading system for loading, identifying the system model, and determining an initial value of a system model parameter.
After the off-line test part is finished, the operation of the on-line test part is carried out, and the specific operation process is as follows:
firstly, calculating the expected displacement y of the test piece a Then, the least square method with forgetting factor is adopted to update the system model parameters on line, and then the self-adaptive time-lag compensation output displacement y is calculated ac Inverse model compensation to obtain the command displacement y of the controlled object c Shift the command by y c Sending the measured displacement to a loading system, loading the test piece, and measuring the measured displacement and the counter force f of the test piece e Get from t ←t + delta t, directly returning to calculating the expected displacement y of the test piece a And the process is repeated circularly throughout the whole real-time mixing test.
The fifth concrete implementation mode: the present embodiment is further limited to the first, second, third or fourth embodiments, in which the first-stage coarse compensation operation is used as a conventional compensation method without online parameter update, and the second-stage fine compensation operation requires online parameter identification and update.
The basic principle of applying the method of the present invention to perform the real-time mixing test is described below by using the real-time mixing test of the magnetorheological damper as a specific embodiment in conjunction with the attached fig. 1, fig. 2, fig. 3, fig. 4 and fig. 5 of the specification.
FIG. 1 is a schematic diagram of two-stage adaptive skew compensation using polynomial extrapolation as the first-stage compensation method,
fig. 2 is a schematic diagram of two-stage adaptive skew compensation using an inverse model method as a first-stage compensation method.
FIGS. 4 and 5 are flow charts of the real-time mixing test of the magnetorheological damper by applying the method of the invention. Wherein, fig. 4 is a flow chart of a real-time mixing test of the magnetorheological damper by applying the method of fig. 2, and fig. 5 is a flow chart of a real-time mixing test of the magnetorheological damper by applying the method of fig. 3.
Wherein, FIG. 2 shows the same structure of the two-stage adaptive skew compensation in the frame between the numerical substructure and the loading system of FIG. 1.
The first embodiment is as follows: the embodiment is described with reference to fig. 1, fig. 2 and fig. 4, where fig. 1 is a schematic diagram of a real-time mixing test of a magnetorheological damper, and includes a numerical solution module, a two-stage adaptive time-lag compensation module, a loading control system module, a magnetorheological damper and a magnetorheological damper semi-active control module;
the method of the invention is elaborated by taking a real-time mixing test of the magnetorheological damper as an example. The magneto-rheological damper is an intelligent shock absorber, has the advantages of large output, small energy consumption, quick response, continuously adjustable performance and the like, and is widely applied to the fields of vehicles, machinery, buildings, medical treatment and the like. In a real-time mixing test, the magnetorheological damper is generally used as a test substructure and an actuator for loading, and other parts of the structure are used as a numerical substructure. Therefore, large-scale and even full-scale tests can be realized, and more accurate and effective test results can be obtained. Due to the strong nonlinear characteristic of a loading system, time lag compensation is always an urgent problem to be solved in a real-time mixing test of the magnetorheological damper. The conventional time-lag compensation method is influenced by uncertain factors, and the compensation effect is not ideal. The time lag compensation is carried out on the real-time mixing test of the magneto-rheological damper by adopting the method disclosed by the invention, and a good compensation effect can be obtained. The method comprises two stages:
first-stage rough compensation:
carrying out early-stage off-line tests, and estimating the steady time lag of the real-time hybrid test system; compensating the system time lag by adopting a polynomial extrapolation method;
secondary fine compensation: and further improving the compensation performance by adopting a self-adaptive time lag compensation method based on a discrete model, namely estimating discrete model parameters on line by adopting test command displacement and test piece actual displacement, and finely compensating the residual time lag by adopting a corresponding compensator.
The following describes the two-stage adaptive skew compensation method of the present invention in detail. FIG. 2 is a schematic diagram of adaptive time lag compensation of a real-time mixing test, and FIG. 4 is a flow diagram of a real-time mixing test of the magnetorheological damper. The flow chart is divided into an off-line test part and an on-line test part. The specific process is as follows:
off-line testing part:
the method comprises the following steps: building test equipment and establishing a numerical substructure and a magneto-rheological damper model;
step two: calculating the command displacement of the magnetorheological damper in the early off-line test;
step three: sending the command displacement to a transmission system to be used as an actuator for loading;
step four: measuring the actual measurement displacement of the off-line test magnetorheological damper, calculating the time lag tau of the system, and taking the initial value theta of the system model parameter 0 Is [1,0 ]]；
On-line test section:
step five: calculating an expectation of a magnetorheological damperDisplacement y a ；
Step six: the module (2) adopts a three-parameter least square method with forgetting factors to estimate system model parameters, and the parameters are output to obtain a module (3);
step seven: desired displacement y for module (1) a And the module (3) calculates the output displacement y of the adaptive time lag compensation according to the parameters ac ；
Step eight: the module (4) adopts a polynomial extrapolation method to compensate the system time lag tau in the step four to obtain the command displacement y of the control object c ；
Step nine: shift the command by y c Sending the signal to an actuator, loading the magnetorheological damper of the module (5) by a transmission system, and measuring the displacement response y m And a counter force;
step ten: and repeating the operation process from the fifth step to the ninth step until the test is finished.
Example two: the embodiment is described with reference to fig. 1, fig. 3 and fig. 5, and the embodiment describes the method in detail by taking the implementation of the real-time mixing test of the high-frequency loading target magnetorheological damper as an example. The conventional time-lag compensation method can amplify high-frequency signals to different degrees, so that time lag is not compensated, the amplitude of output response has larger error, and the time-lag compensation effect of a control system is greatly reduced. The time lag compensation is carried out on the real-time mixed test of the magneto-rheological damper by adopting the method of the invention, and the two-stage self-adaptive time lag compensation method is divided into two stages:
first-stage rough compensation:
identifying the loading system model through a preliminary off-line test, and representing by using a transfer function; performing time lag compensation by using an inverse model of the model as a controller;
first-stage fine compensation:
and a self-adaptive time lag compensation method is adopted as outer loop control, parameter estimation is carried out by adopting the test expected displacement and the displacement output by the test piece, and the residual time lag of the system is compensated.
The following describes the two-stage adaptive time lag compensation method based on the inverse model in detail with reference to the accompanying drawings. FIG. 3 is a schematic diagram of adaptive time-lag compensation of a real-time mixing test, and FIG. 5 is a flow diagram of a real-time mixing test of a high-frequency loading target magnetorheological damper. The flow chart is divided into an off-line test part and an on-line test part. The specific process is as follows:
off-line testing part:
the method comprises the following steps: building test equipment and establishing a numerical substructure and a magneto-rheological damper model;
step two: calculating the command displacement of the magnetorheological damper in the early off-line test;
step three: sending the command displacement to a transmission system to be used as an actuator for loading;
step four: measuring the actual measurement displacement of the magnetorheological damper in the off-line test, identifying the system model off-line, and taking the initial value theta of the parameter of the system model 0 Is [1,0 ]]；
On-line test section:
step five: calculating the expected displacement y of the magnetorheological damper a ；
Step six: the module (2) estimates system model parameters by adopting a three-parameter least square method with forgetting factors, and the parameters are output to obtain a module (3);
step seven: desired displacement y for module (1) a And the module (3) calculates the output displacement y of the adaptive time lag compensation according to the parameters ac ；
Step eight: the module (4) adopts an inverse model method to carry out first-stage compensation to obtain the command displacement y of the control object c ；
Step nine: displacing the command by y c Sending the signal to an actuator, loading the magnetorheological damper of the module (5) by a transmission system, and measuring the displacement response y m And a counter force f e ；
Step ten: and repeating the operation process from the fifth step to the ninth step until the test is finished.
The test piece is a magnetorheological damper, a viscous damper, a tuned mass damper, an anti-buckling support or other target objects, and is specifically arranged according to different test objects, the loading system is an existing system, specifically an axial dynamic test loading system, an earthquake simulation vibration table loading system and other vibration simulation loading systems, and the actuator is an existing device, specifically an electro-hydraulic servo actuator, an electromagnetic servo actuator or other types of actuators. The process of mutually matching the test piece, the loading system and the actuator is the same as the process of mutually matching the existing test piece, the loading system and the actuator. The operation of other necessary components not mentioned in the process of performing the real-time mixing test is also the same as the prior art. In order to test the compensation performance of the invention, a comparative test is carried out between the invention and the existing conventional compensation mode, and three seismic records and four structural separation schemes of the real-time hybrid test Benchmark model are calculated and analyzed. Test results show that the polynomial extrapolation time lag compensation method, the discrete model-based adaptive compensation method and the 8 corresponding maximum values of the calculation indexes are respectively 6.74%,3.80% and 1.86%. The smaller the value is, the better the compensation effect is, and the compensation effect of the invention in the aspect of reducing errors is obvious advantage.
Claims (4)
1. A two-stage time lag compensation method suitable for a real-time mixing test is characterized by comprising the following steps: the method is a process of performing secondary fine compensation on residual time lag of a loading system by using a self-adaptive time lag compensation method based on a discrete model after primary coarse compensation is performed on the loading system;
the process of performing the primary coarse compensation and the secondary fine compensation on the loading system comprises the following steps:
first-stage rough compensation: obtaining system time lag according to the early off-line test, and roughly compensating the system time lag by utilizing a polynomial extrapolation method;
secondary fine compensation: further compensating the time lag of a loading system according to a self-adaptive time lag compensation method based on a discrete model, firstly estimating parameters of the discrete model by matching test expected displacement and test actual displacement, and then compensating the residual time lag of the loading system by using a corresponding compensator;
when the polynomial extrapolation method is a third-order polynomial extrapolation method, the ith command displacement y of the loading system is obtained according to the calculation formula of the third-order polynomial extrapolation method c,i Detailed description of the inventionThe calculation formula is as follows:
in the above formula, y ac,i Inputting displacement for the ith step of the polynomial extrapolation control module; eta is a first time parameter;
in the secondary fine compensation calculation process, a self-adaptive compensation method based on a discrete model is used for calculation, and when the parameter model is a three-parameter model, the i-th step input displacement y of the polynomial extrapolation method control module is calculated through the three-parameter model ac，i The process of (2) is as follows:
y ac，i ＝θ a，1 y m，i +θ a，2 y m，i-1 +θ a，3 y m，i-2
in the above formula, θ a,1 、θ a,2 And theta a,3 Three parameters are adopted; y is m,i 、y m,i-1 And y m,i-2 The measured displacement of the test piece in the ith step, the ith-1 step and the ith-2 step is obtained;
estimating discrete model parameters on line by using a recursive least square method with forgetting factors, wherein the calculation formula is as follows:
ψ i ＝[y m，i y m，i-1 y m，i-2 ]
in the above formula, the first and second carbon atoms are,
is an estimate of the parameter in step i->
Is the parameter estimation value of the step i-1, rho is a forgetting factor, y m,i The measured displacement of the test piece in the step i is obtained; psi i Is and>
respectively an actual measurement displacement vector and a transposition thereof, and P is a covariance matrix;
in the secondary fine compensation calculation process, the calculation formula of the fine compensation is as follows:
in the above formula, the first and second carbon atoms are,
is theta a,1 In combination with an evaluation value of>
Is theta a,2 Is evaluated by the evaluation unit>
Is theta a,3 Estimated value of (a), y a,i To load the desired displacement of step i of the system, y a,i-1 To load the expected displacement of step i-1 of the system, y a,i-2 The expected displacement of the i-2 step of the system is loaded. />
2. The two-stage skew compensation method of claim 1, wherein: the first time parameter eta is the ratio of the time lag tau of the loading system to the time step delta t of the data point, and the calculation formula of the first time parameter eta is as follows:
in the above formula, the time lag τ of the loading system is calculated by an off-line test part, and Δ t is the time step of the data point.
3. The two-stage skew compensation method of claim 1, wherein: the polynomial extrapolation method is replaced by an inverse model method, before the first-stage time lag compensation is completed by using the inverse model method, a system model is identified, and when the identification system model is a second-order transfer function model, a calculation formula of the second-order transfer function model is as follows:
in the above formula, s, ω, and ζ represent the laplace variable, the equivalent circular frequency, and the equivalent damping ratio, respectively.
4. A two-stage skew compensation method for use in a real-time mixing assay as claimed in claim 1 or 3, wherein: the parameters of the first-stage rough compensation operation are not required to be updated online, and the parameters of the second-stage fine compensation operation are required to be identified and updated online.
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