CN1851572A - Method for designing inner mould self-setting digital controller - Google Patents

Abstract

The present invention adopts single-order plus dead-time model; said upper computer controlling output panel control board key to make systems operation on ' identifying stage ', at this point, the relay identifying link switched into closed loop system; under action of relay link, after beginning systems operation, at short notice establishing limit loop; according to real-time measurement to relay output each parameter and biasing relay feed-back identifying formulae to calculate out system identifying three parameters: K, Theta and Pi, and storing in RAM. According to identified model parameter, system calculates each parameter of novel internal mold controller, computational result stored in RAM memory unit, the obtained model and internal mold controller parameter loading in each link in real production process. The present invention realizes the self calibration of digit internal mold controller, reducing hardware cost and raising systematical mobility, reliability and accuracy.

Description

The method for designing of inner mould self-setting digital controller

Technical field

The present invention relates to the method in a kind of industrial process control technology field, specifically is a kind of method for designing of inner mould self-setting digital controller.

Background technology

1979, internal model control structure (IMC) is at first proposed according to Smith predictive compensation control principle by Brosilow, later begun to propose a kind of unified basic structure from typical single-input single-output system calcspar by Carcia and MorariGarcia, the internal model control technology has been applied in many industrial control processes, be acknowledged as one of advanced control method that is best suited for industrial practical application, but have following three difficult problems in present application: engineering technical personnel can't know that how fast and effectively the adjustment control parameter is to reach the compromise between system performance and the robustness when the application conventional manual is adjusted controller, robust stability and nominal output response how to regulate and improve in the industrial control process also are current control difficult problems, how effectively the internal model control technology to be applied to Correction for Large Dead Time System and all not to be solved completely always.

Should be noted that, because overwhelming majority research at present concentrates on parameter estimation and convergence analysis aspect, ignored the test signal design in the discrimination method, and the research of test experiments and model validation verification part, these combine aspect the most closely with practical application just.The dynamic perfromance that the test signal necessary fully dynamics of excitation system, especially control system analysis and designing institute are concerned about, this is the key factor that guarantees identification result validity.

Find  str  m, K.J. through literature search to prior art, with H  gglund, the method that T. proposes relay feedback identification the earliest in 1984, this method acts on the closed loop of system, acquisition process critical message rapidly and accurately, thereby design PID controller.After proposing in 1984, many improvement and extended method are put forward in succession, at unstable object, Wang.Q.G. at document Low-ordermodeling from relay feedback, (Ind.Eng.Chem.Res.1997,36 (2), 375-381.) (the low order modeling method based on relay feedback is published in Industrial ﹠amp; EngineeringChemistry Research, chemical engineering industry and engineering research), middle first Application band biased relay obtains more accurate identification result, need not any prior imformation, and utilize single identification experiment just can obtain more multisystem characteristic easily about time lag and static gain.The present invention combines relay feedback technology and IMC controller design method, and the design control module has been alleviated three difficult problems in the application of IMC controller to a great extent.

Summary of the invention

The objective of the invention is at the deficiencies in the prior art, a kind of method for designing of inner mould self-setting digital controller is proposed, make it based on the controller of relay feedback identification technology realization fast and effectively online self-tuning, can be under the situation that does not redesign controller, automatically the uncertain real-time update of handling the working control object is provided with controller parameter, and success be applied to Correction for Large Dead Time System, reach comparatively satisfied control effect.

The present invention is achieved by the following technical solutions, the present invention is directly operation and enforcement in existing control electronics and industrial computer, at first select " running status automatically " by operator's console control system interface, enter this process after, concrete steps are as follows:

Step 1: adopt first-order plus time delay model commonly used in the Industrial Engineering: $G\left(s\right)=\frac{{\mathrm{Ke}}^{-\mathrm{\θs}}}{\mathrm{\τs}+1}$ Wherein three parameter to be identified: k are system's static gains; θ is system's time lag; τ is a system time constant.

Step 2: PC control output control desk control push-key makes system operate in " identification stage ".At this moment, the relay identification link is switched into closed-loop system.

Step 3: under the effect of relay link, set up limit cycle at short notice after system's operation beginning.

By the monitoring modular to the stable oscillation stationary vibration limit cycle of system output, each output parameter A of single limit cycle that relay feedback produces _u, A _d, T _U1And T _U2Be recorded in the RAM storer.

Step 4: according to the real-time measurement of relay being exported each parameter, according to following bias voltage relay feedback identification formula

$k=\frac{{\∫}_0^{T_{u1}+T_{u2}}y\left(t\right)\mathrm{dt}}{{\∫}_0^{T_{u1}+T_{u2}}u\left(t\right)\mathrm{dt}}---\left(1\right)$

$\mathrm{\θ}=\ln \frac{(u_0+u)K-\mathrm{\ϵ}}{(u_0+u)K-A_u}---\left(2\right)$

$\mathrm{\τ}=T_{u1}{\left(\ln \frac{2\mathrm{uK}{e}^{\mathrm{\θ}}+u_{0}K-\mathrm{uK}+\mathrm{\ϵ}}{\mathrm{uK}+u_{0}K-\mathrm{\ϵ}}\right)}^{-1}---\left(3\right)$

Three parameter K, θ and τ that the system that calculates is to be identified, and deposit among the RAM.

Step 5: calculate each parameter of novel internal mode controller according to the model parameter that has picked out, result of calculation deposits in the ram memory cell.

A. the continuous model parameter that picks out is done discretize and is handled, and for example selects zero-order holder for use, and the system that obtains passes letter:

${\mathrm{HG}}_m\left(z\right)=L\left\{\frac{1-e^{-T_{s}s}}{s}{G}_p\left(s\right)\right\}---\left(4\right)$

B. pass letter character according to discrete system and calculate G ₊(z), G ₊(z) be defined as follows:

$G_{+}\left(z\right)=z^{-(l+1)}\underset{i=1}{\overset{p}{\mathrm{\Π}}}\left(\frac{z-z_i}{z-{\hat{z}}_i}\right)\left(\frac{1-{\hat{z}}_i}{1-z_i}\right)---\left(5\right)$

Wherein l represents the umber of beats that lags behind, and l+1 considers zeroth order, the limit number outside the p representation unit garden, z _iNumber at zero point outside the representation unit garden, ${\hat{z}}_i=1/z_i$ (i＝0，1，2...)

C. the factorization system passes letter, and is as follows:

G _m(z)＝G ₊(z)G _-(z) (6)

D. design internal mode controller, as follows:

$G_c\left(z\right)=\frac{1}{G_{-}\left(z\right)}---\left(7\right)$

E. design system wave filter, as follows:

$G_f\left(z\right)=\frac{1-\mathrm{\α}}{1-\mathrm{\α}{z}^{-1}}---\left(8\right)$

Step 6: send in corresponding each link of actual production process by the model and the internal mode controller parameter of identification gained.Then, system enters " operation phase ".In this stage, the output monitoring module is in running order always, the output of real-time detecting system, no matter be system mismatch or perturbation, still the interference of uncertain disturbance make system's output far away depart from nominal value the time, system automaticallyes switch and enters " identification stage " with each parameter in the production run that upgrades in time.

More than various in: k-system static gain, θ-system's time lag, τ-system time constant, A _dThe positive peak of-object output oscillating curve, A _uThe negative peak of-object output oscillating curve, T _U1High level is held time in-object the input signal, T _U2Low level is held time in-object the input signal, ε-relay time lag constant, u ₀The output of-relay voltage, u-relay output voltage biasing y (t)-object output function analytic expression, u (t)-relay output function analytic expression, T _sIn-discrete control system the sampling time, α-wave filter is regulated parameter, G _p(s)-and the Model Transfer function, HG _m(s)-comprise the object discrete transfer function of zero-order holder, G ₊(s)-and model inner function transport function, G _-(s)-and model outer function transport function, G _c(s)-and novel internal mode controller transport function, G _f(s)-system filter device transport function.

The present invention adds intelligent relay feedback module on existing internal mode controller method for designing.Utilize the relay feedback technology to have realized adjusting certainly of digital internal mode controller with the advantage of the frequency domain information of closed loop controllable mode extraction system.Greatly facilitate the application of industry spot like this, simultaneously, final internal mode controller is designed to digitial controller and is applied in the discrete domain, and controller is finished the dirigibility that has further reduced hardware cost and improved system, reliability and accuracy by programming.

The present invention realizes the Based Intelligent Control to relay identification, thereby can directly implement in existing industrial control system by establishment control corresponding module, realizes adjusting certainly of internal model control system.Startup starting stage of using at the scene for example: in closed loop, pick out the system model parameter fast and accurately by the relay feedback technology, thereby set each parameter of internal mode controller, make system enter the stage of control operation rapidly.In operational process: if the excessive mismatch of model, system can in time switch to the identification state, at short notice the parameter of each model of tracking correction and controller.Outstanding advantage of the method is that the relay identification process is in the closed loop, so even in the identification process of short time, industrial processes still can continue, can not cut off control loop because identification needs influences ordinary production.

The application that another outstanding advantage of the present invention is a relay closed-loop identification has fast and effectively remedied the undue restriction that relies on model accuracy of internal mode controller design.Because the dynamic tracking that the ingenious adding of the quick identification of relay feedback, novel internal mode controller become in the time of can realizing input or model, thereby fundamentally overcome in the internal mode controller design the model mismatch and the too sensitive issue that perturbs.In addition, the application of wave filter link has also improved the robustness of system, can regulate wave filter and compromise between nominal performance and robustness easily.

Control method among the present invention also in conjunction with the application of relay feedback, has been made improvement to classical internal model control algorithm, thereby has effectively solved the out of control problem of internal model control structure to the large time delay link.

On total, the present invention has fundamentally solved the Three Difficult Issues that run into of classical internal mode controller in application: how to realize that from adjusting it is too high to the accuracy requirement of system model how to solve internal model control, how to control the industrial object that has the large time delay link.Simultaneously, the advantage of classical internal model control structure has also obtained fully playing in the present invention.

Description of drawings

Fig. 1 represents each parametric measurement of limit cycle in the experiment of bias voltage relay.

Fig. 2 represents that the present invention uses control block diagram in process of production.

Fig. 3 is the inventive method process flow diagram.

Fig. 4 is the hardware structure diagram that the embodiment of the invention adopts.

Fig. 5 is the effect legend of implementing at a chemical industry example, after Fig. 5 (a) shows application model perturbation 20% of the present invention, in the control effect of process with long time delay; Fig. 5 (b) demonstrates in the model perturbation and arrives at ± 20% o'clock respectively, the applicable cases of the inventive method.

Embodiment

Below in conjunction with drawings and Examples technical scheme of the present invention is further described.

As shown in Figure 1, be illustrated under the biased relay effect, object input signal to be identified is a diagram cycle square wave, exports periodic signal accordingly.

As shown in Figure 2, expression the present invention uses control block diagram in process of production, according to the folding situation of two push-keys, and the control system operation.

As shown in Figure 3, be the inventive method process flow diagram, total system is according to this process flow operation.

As shown in Figure 4, system is mainly by operating console, and host computer is exported control desk and the output monitoring modular constitutes.Operation control platform is a user interface, can select manually or automatic mode these engineering technical personnel, and simultaneously, the real-time output response of system's operation can show record or printing.Technician's management for convenience, operator's console also is provided with warning device.Host computer matches with clock signal, the frequency of control sampling input and Data Update.The output control desk is accepted the control command of host computer and is come control system two push-key switched system two states in service.All the time output in real time detects the output monitoring modular to system, and will import host computer after the information discretize, is in time judged system running state and whether is needed more new data of switching state by the set algorithm routine of host computer.

Fig. 5 is the effect legend of implementing at a chemical industry example.

Wherein, after Fig. 5 (a) shows application model perturbation 20% of the present invention, in the control effect of process with long time delay.The method for designing of the novel inner mould self-setting digital controller that the present invention provides (solid line) and traditional Cohen-Coon automatic setting method (dotted line) are compared.No matter be the rapidity of dynamic response, a plurality of indexs such as stability and static error have all demonstrated superiority.It is to be noted also that under equal conditions classical Ziegler-Nichols PID automatic setting method and improved Ziegler-Nichols (RZN) PID automatic setting method all lost efficacy.Fig. 5 (b) demonstrates in the model perturbation and arrives at ± 20% o'clock respectively, the applicable cases of the inventive method.As can be seen since perturbation can be reflected in the output response the influence of system, by the explanation of output monitoring modular, the basis for estimation that the output response of this moment can be switched as system.Experiment also further is generalized to other model mismatches, the influence of factors such as uncertain interference, and result's proof can be used the inventive method and in time proofread and correct.

Examples of implementation:

Chemical industry large dead time production run to a broad research employing

$G\left(s\right)=\frac{e^{-20s}}{s+1}$

Use the control method step that the present invention provides.

The first step: adopt single order to add pure stagnant ring model $G\left(s\right)=\frac{{\mathrm{Ke}}^{-\mathrm{\θs}}}{\mathrm{\τs}+1},$ Wherein three parameter to be identified: K are system's static gains; θ is system's time lag; τ is a system time constant.

Second step: select to enter " operation phase automatically " by the operator's console control system, control PC control output control desk control push-key makes system operate in " identification stage ", at this moment, the relay identification link is switched into closed-loop system, and limit cycle is set up in system's output.

The 3rd step: system's detection module is to the on-line measurement of the stable oscillation stationary vibration limit cycle of system's output, and the single relay feedback is tested each output information A of the limit cycle that produces _u, A _d, T _U1And T _U2Be recorded in the RAM storer.

The 4th step: according to formula (1) (2) (3), three parameter k=1 that the system that calculates is to be identified, τ=1.042 and θ=20 deposit among the RAM.

The 5th step: calculate each parameter of novel internal mode controller according to the model parameter that has picked out, result of calculation deposits in the ram memory cell.The continuous model parameter that picks out is done discretize and is handled, and for example selects zero-order holder for use, obtains system according to formula (4) and passes letter, calculates G according to formula (5) again ₊(z).Pass letter according to (6) factorization system, then according to formula (7) design internal mode controller

At last according to formula (8) designing filter $G_f\left(z\right)=\frac{0.1}{1-0.9z^{-1}}.$

The 6th step: the model and the internal mode controller parameter of identification gained are sent in corresponding each link of actual production process.Control system enters " operation phase ".In this stage, the output monitoring module is in running order always, the output of real-time detecting system, no matter be system mismatch or perturbation, still the interference of uncertain disturbance make system's output far away depart from nominal value the time, system automaticallyes switch and enters " identification stage " with each parameter in the production run that upgrades in time.

The method for designing of the novel inner mould self-setting digital controller that proposes in the present invention of Industry Control field by using, intelligent even maximum characteristics have, can do on-line tracing to the nominal performance and the robustness of system, thereby effectively realize from adjusting.Simultaneously, can implement effective control equally to process with long time delay.The user operates easier to be directly perceived; The control effect is quick and stable more, can reach better system performance.Take the industrial control system of control method of the present invention can be widely used in the production run control of all kinds of enterprises in the industries such as the energy, metallurgy, petrochemical industry, light industry, medicine, building materials, weaving.

Claims (3)

1, a kind of method for designing of inner mould self-setting digital controller is characterized in that, may further comprise the steps:

Step 1: adopt the first-order plus time delay model: $G\left(s\right)=\frac{{\mathrm{Ke}}^{-\mathrm{\θs}}}{\mathrm{\τs}+1}$ Wherein three parameter to be identified: K are system's static gains; θ is system's time lag; τ is a system time constant;

Step 2: PC control output control desk control push-key makes system operate in " identification stage ", and at this moment, the relay identification link is switched into closed-loop system;

Step 3: under the effect of relay link, set up limit cycle at short notice after system's operation beginning;

Step 4:, calculate system three parameter K, θ and τ to be identified according to bias voltage relay feedback identification formula, and deposit among the RAM according to the real-time measurement of relay being exported each parameter;

Step 5: calculate each parameter of novel internal mode controller according to the model parameter that has picked out, result of calculation deposits in the ram memory cell;

Step 6: send in corresponding each link of actual production process by the model and the internal mode controller parameter of identification gained, then, system enters " operation phase ", in this stage, the output monitoring module is in running order always, and no matter the output of real-time detecting system is system mismatch or perturbation, still the interference of uncertain disturbance make system's output far away depart from nominal value the time, system automaticallyes switch and enters " identification stage " with each parameter in the production run that upgrades in time.

2, the method for designing of inner mould self-setting digital controller according to claim 1, it is characterized in that: described step 3, by monitoring modular to the stable oscillation stationary vibration limit cycle of system output, by the monitoring modular to the stable oscillation stationary vibration limit cycle of system output, each output parameter A of single limit cycle that relay feedback produces _u, A _d, T _U1And T _U2Be recorded in the RAM storer.

3, the method for designing of inner mould self-setting digital controller according to claim 1 is characterized in that: described step 5, calculate each parameter of novel internal mode controller according to the model parameter that has picked out, specific as follows:

A. the continuous model parameter that picks out is done discretize and is handled, and the system that obtains passes letter:

${\mathrm{HG}}_m\left(z\right)=L\left\{\frac{1-e^{-T_{s}s}}{s}{G}_p\left(s\right)\right\}$

B. pass letter character according to discrete system and calculate G ₊(z), G ₊(z) be defined as follows:

$G_{+}\left(z\right)=z^{-(l+1)}\underset{i=1}{\overset{p}{\mathrm{\Π}}}\left(\frac{z-z_i}{z-{\hat{z}}_i}\right)\left(\frac{1-{\hat{z}}_i}{1-z_i}\right)$

Wherein l represents the umber of beats that lags behind, and l+1 considers zeroth order, the limit number outside the p representation unit garden, z _iNumber at zero point outside the representation unit garden, ${\hat{z}}_i=1/z_i$ (i＝0，1，2…)

C. the factorization system passes letter: G _m(z)=G ₊(z) G _-(z)

D. design internal mode controller: $G_c\left(z\right)=\frac{1}{G_{-}\left(z\right)}$

E. design system wave filter: $G_f\left(z\right)=\frac{1-\mathrm{\α}}{1-{\mathrm{\αz}}^{-1}}.$

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