A closed loop convergence system with a substitute PID regulation

Abstract

The application discloses a closed loop convergence system of substituted PID regulation, which can be applied to diesel engine speed control of diesel locomotive, and comprises a control part and a controlled part, the control part is used for accepting an instruction signal and a feedback signal of the controlled part, and sending a control signal to the controlled part; the controlled part is used for accepting the control signal, sending the feedback signal, and realizing controlled movement under the action of the control signal; the control part comprises an envelope line second-order differential link, and the envelope line second-order differential link is equivalent to a PID control link. Through the principle research and model analysis of the PID regulation system, the number of setting parameters of the closed loop convergence system is reduced to one, and the closed loop convergence system with only one parameter setting can realize the effect of the previous PID regulation system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of engineering control technology, in particular to a closed-loop convergence system replacing PID regulation. BACKGROUND

[0002] In the closed-loop convergence system in the field of engineering control, the ideal output of the controlled object should be controllable convergence or at least stable within the tolerance range, so that the transfer function of the closed-loop convergence system generally includes a proportional element (P), an integral element (I) and a differential element (D), so as to maintain the control system in a stable state. Such a closed-loop convergence system is simply referred to as a PID regulation system.

[0003] For a PID regulation system, it is crucial to quickly, accurately and reasonably determine P, I and D parameters. In the case where the transfer function is determined, the determination of the three parameters P, I and D plays a decisive role in the effect of the PID regulation system. However, since the three parameters P, I and D jointly act on a transfer function, the effects of the transfer function are interdependent and interlocked, and the adjustment of any one of the three parameters may affect the effects of the other two. Therefore, in fact, the optimization of the PID regulation system should be the selection and determination of a most suitable three-dimensional numerical point in the space with P, I and D as coordinates, which is called parameter setting of the PID regulation system in the profession.

[0004] The traditional parameter setting of the PID regulation system is to adjust the three parameters P, I and D one by one, and gradually find the suitable three-dimensional numerical point through constant weighing and correction. In theory, the parameter setting of the PID regulation system can be determined by direct theoretical calculation, but the error is too large in practice. At present, the most commonly used parameter setting method for the PID regulation system is the engineering setting method, such as the experience method, the decay curve method, the critical proportion method, the reaction curve method, etc.

[0005] Experience method. Also called on-site trial method, which is to determine the P, I and D parameter values of a PID regulation system, to apply a disturbance to the control system by changing the given value, and to observe and judge the control curve shape on site. If the curve is not ideal, change the P, I and D parameter values, draw the control process curve again, and repeat the trial until the control system meets the dynamic process quality requirements.

[0006] Decay curve method. The decay curve method is to set 4:1 decay (i.e. the convergence degree of the output signal is 4:1 of the oscillation amplitude ratio between the previous period and the subsequent period) as the setting requirement, to cut off the integral and differential parameters of the regulation system, and to set the pure proportional control parameter P by the trial method to meet the 4:1 decay proportion requirement. Then add I and D parameters one by one, and debug them in the same way until all the parameters are qualified.

[0007] Critical ratio method. First, cut off the integral and differential action of the adjustment system, only add proportional control link, until the system step response to the input appears critical oscillation, record the proportional amplification coefficient and critical oscillation period at this time. Then reduce the proportional coefficient to 50-80% of the original, and set the integral time to a larger value, and observe the response curve. Then reduce the integral time, increase the integral action, and adjust the proportional coefficient accordingly, and repeat the trial and error to get a satisfactory response to determine the parameters of the proportion and integral. Finally, add the differential link according to the actual feedback of the system.

[0008] Reaction curve method. The parameters of the controller are set by using the step response curve. It is assumed that a step signal is applied to the controlled object (open loop system), and the response signal is measured by experimental method. According to the step response curve, some parameters reflecting the dynamic characteristics of the controlled object are determined. On this basis, the P, I and D parameters are determined by actual feedback test.

[0009] The common feature of all the above engineering setting methods is that the P, I and D parameters are set by experimental means, so that the PID regulation system can effectively work at a three-dimensional numerical point determined by the three parameters, and the closed loop control can be effectively converged.

[0010] From the mathematical principle, the setting of the traditional PID regulation system is equivalent to the solution of the three-dimensional Cauchy convergence equation. Any change in P, I and D will inevitably change the convergence effect of the equation as a whole. In the actual setting process, it is often difficult to find the optimal solution set, and even the convergence characteristics of the equation may be deteriorated. This is the theoretical basis for the shortcomings of the existing technical solutions.

[0011] Therefore, the shortcomings of the existing technical solutions can be simply summarized as follows:

[0012] Low success rate of setting. Since the three parameters P, I and D jointly act on a transfer function, the effect of the transfer function is interdependent and interdependent. Therefore, when adjusting any one of the three parameters, the effect of the other two parameters may be affected. Therefore, in the actual setting process, it is often difficult to find the optimal combination, and the probability of successful setting is not high.

[0013] Low efficiency of setting. Due to the above reasons, the success probability of setting is not high, so it takes a long time to find a tolerable solution, and therefore the parameter setting of the PID regulation system often takes a long time and has very low working efficiency. In fact, the parameter setting of the PID regulation system is generally the longest part of the entire closed loop system debugging work.

[0014] The effect of the setting is different. Since the P, I and D parameters jointly act on a transfer function, when the transfer function needs to be adjusted, it is often difficult to determine which parameter to operate, and the effect of the operation of different parameters on the overall transfer function is also different. This results in that the setting effect of the PID regulation system by different operators or the same operator under different operation methods may be very different.

[0015] The setting acceptance is poor, and team communication is difficult. The additional shortcomings based on the third point are that if the setting work is undertaken by different personnel, due to the different selection and operation sequence of the P, I and D parameters, the setting work acceptance is often poor; at the same time, the team cooperation and communication cannot reach the result matching point due to the parameter selection and sequence problem, and effective discussion cannot be carried out, resulting in difficult team communication. SUMMARY

[0016] In view of the shortcomings of the prior art, the purpose of the present application is to provide a closed-loop convergence system which replaces the PID regulation and is more optimized. In the present application, through the in-depth study of the principle of the PID regulation system and the model analysis, the number of setting parameters of the closed-loop convergence system is reduced to one, and the closed-loop convergence system with only one parameter setting can realize the effect of the previous PID regulation system.

[0017] To this end, the present application provides the following technical solutions:

[0018] The present application provides a closed-loop convergence system which replaces the PID regulation, comprising: a control part and a controlled part, the control part being used for accepting an instruction signal and a feedback signal of the controlled part, and sending a control signal to the controlled part; the controlled part being used for accepting the control signal, sending a feedback signal, and realizing the controlled motion under the action of the control signal; the control part comprising an envelope line second-order differential link, the envelope line second-order differential link being equivalent to a PID control link.

[0019] Further, the envelope line second-order differential link controls the output curve convergence of the closed-loop convergence system through the differential of the convergence curve envelope line slope.

[0020] Further, the envelope line second-order differential link controls the output curve convergence of the closed-loop convergence system through the differential of the convergence curve envelope line slope, comprising:

[0021] The differential of the convergence curve envelope line slope is defined as a parameter W, when W increases, the convergence curve converges quickly, and the static tolerance band is small; when W decreases, the convergence curve converges slowly, and the static tolerance band is large.

[0022] Further, the parameter setting of the control part comprises: setting the differential of the convergence curve envelope line slope.

[0023] Further, the control object in the controlled part is the speed of the internal combustion engine of the internal combustion engine vehicle.

[0024] It is proved that the present application is a more optimized closed loop convergent system which substitutes the PID regulation. The beneficial effects include:

[0025] (1) Since the contraction property of the transfer function of the closed loop convergent system in the present application is determined by only one parameter, the difficulty is reduced compared with the three interrelated parameter setting mode of the PID regulation system, and the success rate of the setting work is greatly improved in theory. And the working efficiency of the setting work is also greatly improved compared with the PID regulation system, and the time consumption is shortened.

[0026] (2) Since the parameter setting of the closed loop convergent system in the present application only involves one parameter, the setting effect of the closed loop convergent system remains consistent whether it is different operators or the same operator in different situations, which ensures that the setting work is carried out in a single line and the work acceptance is better; and the unique team interaction point also ensures smooth team cooperation and exchange. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0028] Figure 1 General principle diagram of the PID regulation system in the prior art;

[0029] Figure 2 General convergent curve and setting principle diagram of the PID regulation system in the prior art;

[0030] Figure 3 Envelope line characteristic diagram of the convergent curve in the embodiments of the present application;

[0031] Figure 4 Influence diagram of the envelope line slope differential on the curve convergence in the embodiments of the present application;

[0032] Figure 5 Transfer function table diagram in the embodiments of the present application. DETAILED DESCRIPTION

[0033] In the following, the technical solutions in the embodiments of the present application will be described clearly and completely in conjunction with the drawings in the embodiments of the present application, so that those skilled in the art can better understand the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the scope of protection of the present application.

[0034] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0035] In the control of the internal combustion engine speed of the internal combustion engine vehicle, a closed loop convergence system based on PID regulation is usually adopted, and the closed loop control of the internal combustion engine speed is realized by adjusting three parameters P, I and D. In parameter setting, three parameters affecting each other need to be adjusted, and the parameter adjustment is difficult, and it is difficult to realize accurate control of the internal combustion engine speed. Therefore, the present application proposes a closed loop convergence system instead of PID regulation, and only the slope change rate of the convergence envelope line needs to be set in parameter setting, and the parameter adjustment is simple and fast, and it is easier to realize accurate control of the internal combustion engine speed.

[0036] The inventive concept of the present application is that, based on the analysis of the convergence characteristic curve of a general PID regulation system and the model equivalence research, the slope change rate of the convergence envelope line is obtained as the control parameter of the closed loop convergence system, and the PID regulation is replaced.

[0037] The establishment process and the principle explanation of the technical solutions of the present application will be described in detail as follows:

[0038] The general PID regulation system transfer logic diagram is shown in Figure 1 The time domain function is:

[0039]

[0040] Wherein, U(t) is output, e(t) is input, Kp, Ti, Td are P, I, D three adjusting parameters respectively. The convergence curve and the basic role of P, I, D three parameters in the convergence characteristic of control transfer function are seen from Figure 2 Figure 2 It can be seen from the parameter setting principle of the existing PID adjusting system that the response time is controlled by P parameter, the steady state tolerance bandwidth is controlled by I parameter, and the dynamic response is controlled by D parameter, and the three parameters jointly control the convergence of the output curve.

[0041] Figure 3 The basic principle of the application is shown in the figure, that is, the envelope characteristic of the convergence curve. The smooth continuous curve connecting the peak-peak value of the oscillation of the convergence curve is called envelope, and it can be seen from Figure 3 When the tangent slope k of any point of the envelope is greater than 0 in absolute value, the envelope is in the contraction state, and when the tangent slope k of any point of the envelope is equal to 0, the envelope is in the stable parallel state.

[0042] According to the principle of the relationship between the change of the slope of the envelope of the convergence curve and the convergence of the curve disclosed in Figure 3 , the change rate of the slope of the envelope of the convergence curve, that is, the differential of the slope of the envelope of the convergence curve, can determine the convergence trend of the convergence curve.

[0043] On the basis of the above theory, the specific principle of parameter setting of the closed loop convergence system designed by the application is shown in Figure 4 , the differential of the slope of the envelope of the convergence curve is defined as parameter W, when W increases, the convergence curve converges quickly, and the static tolerance band is small, and when W decreases, the convergence curve converges slowly, and the static tolerance band is large.

[0044] In Figure 4 , the envelope lines represented by the two kinds of dashed lines of red and blue are denoted as W1 and W2 respectively, wherein W1 < W2, and the same oscillation signal with the same initial condition under the two color envelope lines generates different convergence trend lines, which are also represented by the corresponding red and blue solid lines.

[0045] The final technical scheme of the application is obtained through the analysis and thinking conversion of the above theoretical model, that is, the change rate of the slope of the envelope of the convergence curve, that is, the differential of the slope of the envelope of the convergence curve, is used to control the convergence of the output curve of the closed loop convergence system.

[0046] In the mathematical angle, the slope of the envelope is the first order differential of the envelope function, and the differential of the slope of the envelope is the second order differential of the envelope function, and the transfer logic diagram of the closed loop convergence system is shown in Figure 5 .

[0047] ​After equivalent transformation of PID parameters, engineering test and Matlab simulation of optimal test curve, the following formula is obtained Figure 5 A mathematical expression of the closed loop convergence system is as follows:

[0048]

[0049] Wherein, U(t) is output, e(t) is input, w is a regulating parameter, and represents a shrinkage coefficient of the convergence curve envelope.

[0050] Since the shrinkage property of the closed loop convergence system transfer function in the embodiment of the application is determined by only one parameter, the difficulty is reduced relative to the three interrelated parameter setting modes of the PID regulating system, and the success rate of the setting work is theoretically ensured to be greatly improved. And the working efficiency of the setting work is also greatly improved relative to the PID regulating system, and the time consumption is shortened. Meanwhile, since the parameter setting of the closed loop convergence system in the embodiment of the application only involves one parameter, the setting effect of the closed loop convergence system is consistent whether different operators or the same operator in different situations, which ensures that the setting work is carried out in a single line and the work acceptance is better, and the team interaction point is unique, which also ensures smooth team cooperation and exchange.

[0051] In several embodiments provided in the present application, it should be understood that the disclosed technical content can be implemented by other ways. Among them, the device embodiments described above are only schematic, for example, the division of the units can be a logical function division, and actual implementation can have another division way, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units or modules shown or discussed can be indirect coupling or communication connection through some interfaces, units or modules, which can be electrical or other forms.

[0052] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed to multiple units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment scheme.

[0053] In addition, each functional unit in each embodiment of the application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of software functional unit.

[0054] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application, essentially or in other words, the part that contributes to the prior art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium, and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

[0055] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A closed loop convergence system with substitution PID regulation, characterized by, The application relates to a control system, which comprises a control part and a controlled part, the control part is used for accepting an instruction signal and a feedback signal of the controlled part, and sends a control signal to the controlled part; the controlled part is used for accepting the control signal, sending the feedback signal, and realizing a controlled motion under the action of the control signal; the control part comprises an envelope second-order differential link, the envelope second-order differential link is equivalent to a PID control link; the envelope second-order differential link controls the output curve convergence of a closed loop convergence system through the differential of the convergence curve envelope line slope; the envelope second-order differential link controls the output curve convergence of a closed loop convergence system through the differential of the convergence curve envelope line slope, which comprises the following steps: the differential of the convergence curve envelope line slope is defined as a parameter W; when the W increases, the convergence curve converges fast, and the static tolerance band is small; when the W decreases, the convergence curve converges slowly, and the static tolerance band is large; the parameter setting of the control part comprises setting the differential of the convergence curve envelope line slope; the control object in the controlled part is the rotation speed of an internal combustion engine of an internal combustion engine vehicle. ​ ​ ​ ​ 2. A closed loop convergence system with a substituted PID regulation according to claim 1, characterized in that, ​ 3. A closed loop convergence system with a substituted PID regulation according to claim 1, characterized in that, ​

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