CN112051727A - Variable structure control algorithm - Google Patents

Abstract

The embodiment of the disclosure provides a variable structure control algorithm, which adopts an incremental PID control mode, and the incremental PID control mode changes control structure parameters in real time through real-time changed system deviation and deviation change rate. The incremental PID control mode includes a proportional gain portion, an integral gain portion, and a micro-integral gain portion. The calculation formula of the incremental PID control mode of the variable structure control algorithm is as follows:

the variable structure algorithm has the advantage that the algorithm model can smooth the whole system control and adjustment process.

Description

A Variable Structure Control Algorithm

technical field

The present disclosure relates to the technical field of industrial control, and in particular, to a variable structure control algorithm.

Background technique

In industrial control, electro-hydraulic control is a typical time-delay control system, which requires high control performance such as control accuracy, adaptability and robustness of hydraulic control algorithms. The working principle of the hydraulic control system is to adjust the hydraulic oil flow through the electronic control system, thereby changing the current hydraulic pressure, thereby driving the relevant execution structure to respond, and implementing the acquisition of the current position of the actuator, and judging whether the current adjustment control process has met the requirements.

From the function analysis, the hydraulic control system needs to adjust the hydraulic flow in real time to realize the real-time adjustment of the hydraulic pressure; from the performance analysis, the hydraulic control system needs to be based on the function realization, to meet the corresponding adjustment time, overshoot, adjustment process smoothness, etc. Constraints. However, existing hydraulic control systems have the following disadvantages:

1. The control system is uncertain, and the adjustment parameters of the internal controller cannot be adjusted in real time;

2. For a complex hydraulic control system, it needs to establish a complex control object model in order to achieve precise control of the hydraulic control system;

In a word, the existing hydraulic control system has the problems of weak robustness and low control precision.

SUMMARY OF THE INVENTION

In view of this, the embodiments of the present disclosure provide a variable structure control algorithm, which can be applied to at least a hydraulic control system of a trailing edge flap, and can partially solve the problems existing in the prior art. The variable structure control algorithm provided by the invention can not only overcome the uncertainty of the hydraulic control system, but also adjust the adjustment parameters of the internal controller in real time. At the same time, it can make the hydraulic control system have a certain degree of adaptability and robustness, so as to solve the complex control system without establishing a complex control object model to achieve precise control.

The design idea of this algorithm is: adopt the incremental PID control mode, break the conventional PID control structure, and change the control structure parameters in real time through the real-time changing system deviation and deviation change rate, thereby improving the response rate of the control system and reducing the system Overshoot, improve system stability.

The technical scheme for realizing the purpose of the invention is as follows: a variable structure control algorithm, the variable structure control algorithm adopts an incremental PID control mode, and the incremental PID control mode changes the control structure parameters in real time through the real-time changing system deviation and the deviation change rate.

Incremental PID control mode includes proportional gain part, integral gain part and calculus gain part. The principle of the variable structure control algorithm of the present invention is: when the deviation of the hydraulic system is large, the proportional gain part takes a larger value, the integral gain part takes a smaller value, and the differential gain part takes a smaller value, so that the hydraulic control system can respond quickly , in order to shorten the adjustment time; when the hydraulic system error is small, the proportional gain part takes a small value, the integral gain part takes a large value, and the differential gain part takes a small value to eliminate the static error of the hydraulic control system and enhance the robustness of the hydraulic control system. Rod; when the deviation of the hydraulic control system changes from large to small, the value of the differential gain part changes from small to large and then becomes small, so as to avoid the large overshoot of the hydraulic control system.

a_p为比例增益范围设定最小值；b_p为比例增益范围调节系数；c_p为比例增益的变化速率。当液压控制系统偏差较小时，比例增益部分的参数取值较小；当液压控制系统偏差较大时，比例增益部分的参数取值较大。比例增益部分参数的变化趋势随系统偏差的变化趋势相同，这样既可以提高控制系统快速响应，也可以防止系统产生过大的超调量，而公式中c_p决定比例增益部分的变化速率。Among them, the proportional gain part is Kp, and the calculation formula of Kp is:

a _p is the set minimum value of the proportional gain range; b _p is the proportional gain range adjustment coefficient; c _p is the rate of change of the proportional gain. When the deviation of the hydraulic control system is small, the parameter value of the proportional gain part is small; when the deviation of the hydraulic control system is large, the parameter value of the proportional gain part is large. The change trend of the proportional gain part parameters is the same as that of the system deviation, which can not only improve the fast response of the control system, but also prevent the system from generating excessive overshoot. In the formula, _cp determines the proportional gain part change rate.

a_i为积分增益范围调节系数；c_i为积分增益的变化速率。当液压控制系统的偏差较小时，积分增益部分的参数取值较大，可消除液压控制系统静差，防止液压控制系统产生震荡和积分饱和现象；当液压控制系统的偏差较大时，积分增益部分的参数取值较小，加快液压控制系统快速响应，而公式中c_i决定了积分增益部分的变化速率。Among them, the integral gain part is Ki, and the calculation formula of Ki is:

a _i is the integral gain range adjustment coefficient; c _i is the rate of change of the integral gain. When the deviation of the hydraulic control system is small, the parameter value of the integral gain part is larger, which can eliminate the static error of the hydraulic control system and prevent the hydraulic control system from generating vibration and integral saturation; when the deviation of the hydraulic control system is larger, the integral gain The value of some parameters is small, which can speed up the fast response of the hydraulic control system, and c _i in the formula determines the rate of change of the integral gain part.

a_d为微分增益范围调节系数；c_d为微分增益的变化速率；ε控制系统偏差系数。当液压控制系统的偏差大时，积分增益部分的参数取值很小，加快液压控制系统快速响应；当液压控制系统的偏差较小时，积分增益部分的参数取值较小；当液压控制系统的偏差由大到小变化过程中，微分增益部分的变化趋势按照正态分布变化趋势变化，可以减小液压控制系统超调量，克服液压控制系统震荡，增强液压控制系统的稳定性及加快控制系统动态响应速率。而公式中c_d决定了积分增益部分的变化速率，液压控制系统的偏差处于ε附近开始增强微分增益作用。Among them, the differential gain part is Kd, and the calculation formula of Kd is:

a _d is the differential gain range adjustment coefficient; _cd is the rate of change of the differential gain; ε controls the system deviation coefficient. When the deviation of the hydraulic control system is large, the parameter value of the integral gain part is small, which speeds up the rapid response of the hydraulic control system; when the deviation of the hydraulic control system is small, the parameter value of the integral gain part is small; When the deviation changes from large to small, the change trend of the differential gain part changes according to the normal distribution trend, which can reduce the overshoot of the hydraulic control system, overcome the shock of the hydraulic control system, enhance the stability of the hydraulic control system and speed up the control system. Dynamic response rate. In the formula, c _d determines the rate of change of the integral gain part, and the deviation of the hydraulic control system starts to enhance the differential gain effect when the deviation of the hydraulic control system is near ε.

The calculation formula of the incremental PID control mode of the variable structure control algorithm is:

Real-time output value for the controller.

Further, the value range of the proportional gain part Kp is 0≤a _p ≤Kp≤(a _p +b _p ).

Further, the value range of the integral gain part Ki is 0≤Ki≤a _i .

Further, the value range of the differential gain part Kd is _0≤Kd≤ad .

Compared with the prior art, the beneficial effect of the present invention is as follows: by adopting the variable structure control algorithm, in the initial stage of adjustment of the hydraulic control system, when the deviation of the hydraulic control system is large, the parameters of the larger proportional gain part are selected, and the parameters of the proportional gain part are selected to be relatively large. The parameters of the small integral gain part and the small differential gain part make the output value of the hydraulic control system larger. For the hydraulic system, the pressure storage time can be reduced and the response speed of the actuator can be accelerated; when the hydraulic control system is When the deviation of the system is small, select the parameters of the smaller proportional gain part, the parameters of the larger integral gain part, and the parameters of the smaller differential gain part, so that the hydraulic control system can enhance the effect of the integral link and avoid the phenomenon of oscillation and integral saturation. , which is beneficial to reduce the overshoot; when the deviation of the hydraulic control system changes from large to small, the proportional gain part and the integral gain part are adjusted with the setting formula, and the differential gain part increases first and then decreases. Due to the large inertia characteristic of the hydraulic control system, in order to overcome the hydraulic control system when it is close to the control target, the hydraulic control system must be braked in advance, and the hydraulic control system can reduce the output of the control amount in advance through the parameters of the differential gain part. It can reduce the overshoot of the hydraulic control system, enhance the problem of the system, and meet the corresponding control performance.

Description of drawings

In order to explain the technical solutions of the embodiments of the present disclosure more clearly, the following briefly introduces the accompanying drawings that need to be used in the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

Fig. 1 is the structural block diagram of the variable structure control algorithm of the present invention;

Fig. 2 is the change trend diagram of the parameter of the proportional gain part of the present invention with the system deviation;

Fig. 3 is the variation trend diagram of the parameter of the integral gain part of the present invention with the system deviation;

Fig. 4 is the variation trend diagram of the parameter of the differential gain part of the present invention with the system deviation;

Fig. 5 is the control flow chart of the variable structure control algorithm of the present invention;

Fig. 6 is the target value of the variable structure control algorithm of the present invention and the simulation trend change diagram of the collected value;

FIG. 7 is a graph of the variation trend of the PID control parameters with the system deviation in the variable structure control algorithm of the present invention.

Detailed ways

The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

The embodiments of the present disclosure are described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only some, but not all, embodiments of the present disclosure. The present disclosure can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments may be combined with each other under the condition of no conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present disclosure.

To illustrate, various aspects of embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms and that any specific structure and/or function described herein is illustrative only. Based on this disclosure, those skilled in the art should appreciate that an aspect described herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented and/or a method may be practiced using any number of the aspects set forth herein. Additionally, such an apparatus may be implemented and/or such a method may be practiced using other structure and/or functionality in addition to one or more of the aspects set forth herein.

It should also be noted that the drawings provided in the following embodiments are only illustrative of the basic concept of the present disclosure, and the drawings only show the components related to the present disclosure rather than the number, shape and the number of components in actual implementation. For dimension drawing, the type, quantity and proportion of each component can be changed at will in actual implementation, and the component layout may also be more complicated.

Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, one skilled in the art will understand that the described aspects may be practiced without these specific details.

The embodiment of the present disclosure provides a variable structure control algorithm, the variable structure control algorithm adopts an incremental PID control mode, and the incremental PID control mode changes the control structure parameters in real time by changing the system deviation and deviation change rate in real time.

Incremental PID control mode includes proportional gain part, integral gain part and calculus gain part. The principle of the variable structure control algorithm in this embodiment is: when the hydraulic system deviation is large, the proportional gain part takes a large value, the integral gain part takes a small value, and the differential gain part takes a small value, so that the hydraulic control system can quickly response to shorten the adjustment time; when the hydraulic system error is small, the proportional gain part takes a small value, the integral gain part takes a large value, and the differential gain part takes a small value to eliminate the static error of the hydraulic control system and enhance the hydraulic control system. Robustness: When the deviation of the hydraulic control system changes from large to small, the value of the differential gain part changes from small to large and then becomes small, so as to avoid the large overshoot of the hydraulic control system.

a_p为比例增益范围设定最小值；b_p为比例增益范围调节系数；c_p为比例增益的变化速率。当液压控制系统偏差较小时，比例增益部分的参数取值较小；当液压控制系统偏差较大时，比例增益部分的参数取值较大。比例增益部分参数的变化趋势随系统偏差的变化趋势相同，这样既可以提高控制系统快速响应，也可以防止系统产生过大的超调量，而公式中c_p决定比例增益部分的变化速率。进一步的，比例增益部分Kp的取值范围为0≤a_p≤Kp≤(a_p+b_p)。比例增益部分的Kp的变化速率如图2所示。Among them, the proportional gain part is Kp, and the calculation formula of Kp is:

a _p is the set minimum value of the proportional gain range; b _p is the proportional gain range adjustment coefficient; c _p is the rate of change of the proportional gain. When the deviation of the hydraulic control system is small, the parameter value of the proportional gain part is small; when the deviation of the hydraulic control system is large, the parameter value of the proportional gain part is large. The change trend of the proportional gain part parameters is the same as that of the system deviation, which can not only improve the fast response of the control system, but also prevent the system from generating excessive overshoot. In the formula, _cp determines the proportional gain part change rate. Further, the value range of the proportional gain part Kp is 0≤a _p ≤Kp≤(a _p +b _p ). The rate of change of Kp in the proportional gain section is shown in Figure 2.

a_i为积分增益范围调节系数；c_i为积分增益的变化速率。当液压控制系统的偏差较小时，积分增益部分的参数取值较大，可消除液压控制系统静差，防止液压控制系统产生震荡和积分饱和现象；当液压控制系统的偏差较大时，积分增益部分的参数取值较小，加快液压控制系统快速响应，而公式中c_i决定了积分增益部分的变化速率。进一步的，积分增益部分Ki的取值范围为0≤Ki≤a_i。积分增益部分Ki的变化速率如图3所示。Among them, the integral gain part is Ki, and the calculation formula of Ki is:

a _i is the integral gain range adjustment coefficient; c _i is the rate of change of the integral gain. When the deviation of the hydraulic control system is small, the parameter value of the integral gain part is larger, which can eliminate the static error of the hydraulic control system and prevent the hydraulic control system from generating vibration and integral saturation; when the deviation of the hydraulic control system is larger, the integral gain The value of some parameters is small, which can speed up the fast response of the hydraulic control system, and c _i in the formula determines the rate of change of the integral gain part. Further, the value range of the integral gain part Ki is 0≤Ki≤a _i . The rate of change of the integral gain part Ki is shown in Figure 3.

a_d为微分增益范围调节系数；c_d为微分增益的变化速率；ε控制系统偏差系数。当液压控制系统的偏差大时，积分增益部分的参数取值很小，加快液压控制系统快速响应；当液压控制系统的偏差较小时，积分增益部分的参数取值较小；当液压控制系统的偏差由大到小变化过程中，微分增益部分的变化趋势按照正态分布变化趋势变化，可以减小液压控制系统超调量，克服液压控制系统震荡，增强液压控制系统的稳定性及加快控制系统动态响应速率。而公式中c_d决定了积分增益部分的变化速率，液压控制系统的偏差处于ε附近开始增强微分增益作用。进一步的，微分增益部分Kd的取值范围为0≤Kd≤a_d。微分增益部分为Kd的变化速率如图4所示。Among them, the differential gain part is Kd, and the calculation formula of Kd is:

a _d is the differential gain range adjustment coefficient; _cd is the rate of change of the differential gain; ε controls the system deviation coefficient. When the deviation of the hydraulic control system is large, the parameter value of the integral gain part is small, which speeds up the rapid response of the hydraulic control system; when the deviation of the hydraulic control system is small, the parameter value of the integral gain part is small; When the deviation changes from large to small, the change trend of the differential gain part changes according to the normal distribution trend, which can reduce the overshoot of the hydraulic control system, overcome the shock of the hydraulic control system, enhance the stability of the hydraulic control system and speed up the control system. Dynamic response rate. In the formula, c _d determines the rate of change of the integral gain part, and the deviation of the hydraulic control system starts to enhance the differential gain effect when the deviation of the hydraulic control system is near ε. Further, the value range of the differential gain part Kd is _0≤Kd≤ad . The rate of change of the differential gain part, Kd, is shown in Figure 4.

The calculation formula of the incremental PID control mode of the variable structure control algorithm is:

It is the real-time output value of the controller, and the structural block diagram of its variable structure control algorithm is shown in Figure 1.

The simulation of the variable structure control algorithm of the above embodiment will be described in further detail below with reference to FIG. 5 , FIG. 6 , and FIG. 7 .

The simulation system requires a target value of 68, a single-step adjustment ≯ 1.5°, a steady-state error of 0.25°, an adjustment time _{≯ 7s} , and a smooth control process. _p , a _i , c _i , a _d , c _d , and ε take the values of 0.30, 0.5, 8.00, 1.00, 0.05, 0.50, 0.08, and 10.00 in sequence. After the simulation test, the variable structure control algorithm meets the control performance requirements of the hydraulic control system. As shown in Figure 6, the entire adjustment process is relatively smooth, and there is no phenomenon that the adjustment rate is too large or too small. As shown in Figure 7, in the early stage of system adjustment, due to the existence of hydraulic energy storage links, the control algorithm model mainly focuses on the control output of the proportional gain part, which speeds up the response of the control system. Oscillation and overshoot phenomenon, the role of the differential gain part first and then decreased, mainly to overcome the inertia link existing in the hydraulic system and reduce the system overshoot; the control algorithm model in the final stage of system adjustment is based on the control output of the integral gain part to enhance the control system. stability and anti-interference ability.

In general, the algorithm model of the variable structure control algorithm of the present invention can smooth the entire system control adjustment process.

The above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited to this. Any person skilled in the art who is familiar with the technical scope of the present disclosure can easily think of changes or substitutions. All should be included within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims (4)

1. a variable structure control algorithm is characterized in that: the variable structure control algorithm adopts the incremental PID control mode, and the incremental PID control mode changes the control structure parameter in real time by the system deviation of real-time change and the deviation rate of change; Incremental PID control mode includes proportional gain part, integral gain part and calculus gain part; Among them, the proportional gain part is Kp, and the calculation formula of Kp is:

a _p is the set minimum value of the proportional gain range; b _p is the adjustment coefficient of the proportional gain range; c _p is the rate of change of the proportional gain; Among them, the integral gain part is Ki, and the calculation formula of Ki is:

a _i is the integral gain range adjustment coefficient; c _i is the rate of change of the integral gain; Among them, the differential gain part is Kd, and the calculation formula of Kd is:

a _d is the differential gain range adjustment coefficient; c _d is the rate of change of the differential gain; ε is the control system deviation coefficient; The calculation formula of the incremental PID control mode of the variable structure control algorithm is:

Real-time output value for the controller. 2 . The variable structure control algorithm according to claim 1 , wherein the value range of the proportional gain part Kp is 0≦ _ap ≦Kp≦( _ap +b _p ). 3 . 3 . The variable structure control algorithm according to claim 1 , wherein the value range of the integral gain part Ki is 0≦Ki≦a _i . 4 . 4 . The variable structure control algorithm according to claim 1 , wherein the value range of the differential gain part Kd is 0≦ _Kd ≦ad . 5 .

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