CN112068430A - Electro-hydraulic proportional valve dead zone compensation algorithm and compensation system - Google Patents

Electro-hydraulic proportional valve dead zone compensation algorithm and compensation system Download PDF

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CN112068430A
CN112068430A CN202010909357.7A CN202010909357A CN112068430A CN 112068430 A CN112068430 A CN 112068430A CN 202010909357 A CN202010909357 A CN 202010909357A CN 112068430 A CN112068430 A CN 112068430A
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fuzzy
dead
error
dead zone
compensation
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何砚高
赵璐
张富程
万宏舸
李涛
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Xian Flight Automatic Control Research Institute of AVIC
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042—Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance

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Abstract

The invention belongs to the field of machine tool machining and the like, and particularly provides an electro-hydraulic proportional valve dead zone compensation algorithm. The method can improve the dead zone compensation precision of the proportional valve, and can adjust the dead zone compensation value on line according to the variable dead zone characteristic of the proportional valve, thereby improving the dynamic characteristic of the dead zone compensation.

Description

Electro-hydraulic proportional valve dead zone compensation algorithm and compensation system
Technical Field
The invention belongs to the field of machine tool machining, and particularly relates to a dead zone compensation algorithm and a compensation system for an electro-hydraulic proportional valve.
Background
With the continuous popularization and application of the electro-hydraulic servo control technology and the electro-hydraulic proportional control technology in various fields, the requirements of people on the control precision and the control quality are higher and higher. The control precision of the electro-hydraulic proportional control is improved, on one hand, the control precision can be realized by changing the valve body structure of the proportional valve and improving the process precision, on the other hand, the control efficiency and the control precision can be improved by adopting an advanced intelligent control algorithm, but the manufacturing and maintenance cost can be greatly increased by changing the valve body structure and the process precision. With the development of computer technology and control theory, more and more intelligent control theory and technology are fully utilized in hydraulic transmission control.
The dead zone of the electro-hydraulic proportional valve is influenced by internal friction damping, electric signal response, hysteresis of a valve core reset spring, valve port pressure drop change, oil temperature change and the like, so that the flow dead zone characteristic of the electro-hydraulic proportional valve is a variable dead zone characteristic, and an accurate mathematical model is difficult to establish. For the variable dead zone characteristic of the proportional flow valve, if the traditional compensation or linear compensation is simply adopted, the ideal dynamic response performance and high positioning accuracy are difficult to obtain.
Disclosure of Invention
The purpose of the invention is as follows: the dead zone compensation algorithm of the electro-hydraulic proportional valve is provided, so that the dead zone compensation precision of the proportional valve is improved, and the dead zone compensation value can be adjusted on line according to the variable dead zone characteristic of the proportional valve, so that the dynamic characteristic of the dead zone compensation is improved.
The invention improves the influence caused by factors such as inherent dead zone and hysteresis loop of the electro-hydraulic proportional valve, variable gain and the like by adopting a proper algorithm, can improve the control performance to a certain extent, and is easy to realize.
The technical scheme of the invention is as follows: in one aspect, a dead-time compensation algorithm for an electro-hydraulic proportional valve is provided, and the dead-time compensation algorithm includes:
determining dead zone range | U of electro-hydraulic proportional valve through experimentd0|；
According to the error threshold ethError change rate threshold ecthDesigning a membership function relation curve among the error e, the error change rate ec and the membership,
according to the absolute value of the error e and the error threshold ethThe magnitude relation between the error rate ec and the absolute value of the error rate ec and the error rate threshold ecthThe magnitude relation between the two, the design of the fuzzy dead zone compensation output UdA membership function curve of (1);
according to the obtained error e, the membership function relation curve between the error change rate ec and the membership and the obtained fuzzy dead zone compensation output UdA membership function curve of the fuzzy control rule table is instantiated;
blurringThe controller deduces fuzzy control quantity and fuzzy dead zone compensation output U by using a fuzzy control rule table according to the input of the error e and the error change rate ecdThe conversion relationship between them;
compensating the initial value U according to the determined dead zoned0Fuzzy dead zone compensation output UdAnd the output voltage U of the main controllerctrlCalculating dead zone compensation output UC(ii) a And the sum of the output of the main controller and the output of the fuzzy dead zone compensation is used for closed-loop control of the proportional valve control hydraulic cylinder system.
Further, the dead zone compensation output is calculated by the formula:
UC＝sgn(Uctrl)(Ud0+Ud)
wherein U isctrlIs the output voltage of the main controller, Ud0Compensating the initial value, U, for dead zonesdFor fuzzy dead-zone compensation output of the fuzzy controller, UCThe dead zone is compensated and output as; sgn is the sign operator.
Further, the compensation amount U is designeddThe membership function curve of (1):
if | e |<ethThe positioning error e meets the precision requirement, and the compensation output quantity of the fuzzy controller is kept unchanged;
if | e |>ethAnd | ec | non-conducting<ecthWhen the output quantity of compensation is under-compensation, the fuzzy controller calculates and increases the output U of fuzzy dead zone compensationd；
If | e |>ethAnd | ec | non-conducting>ecth，e×ec>0, the compensation output quantity is overcompensated, and in order to prevent the system from generating self-oscillation, the fuzzy controller calculates and reduces the fuzzy dead zone compensation output Ud。
Further, determining an error e, a fuzzy subset of the error change rate ec and a fuzzy dead zone compensation output UdThe fuzzy subset of (1);
e,ec＝[NB,NM,NS,ZO,PS,PM,PB]
Ud＝[NB,NM,NS,ZO,PS,PM,PB]
wherein, NB represents the negative big of the fuzzy variable, NM represents the negative middle of the fuzzy variable, NS represents the negative small of the fuzzy variable, ZO represents the zero value of the fuzzy variable, PS represents the positive small of the fuzzy variable, PM represents the middle of the fuzzy variable, and PB represents the positive big of the fuzzy variable.
Further, e is an error value between the expected displacement of the proportional valve control hydraulic cylinder system and the actual displacement fed back by the displacement sensor.
Further, the error change rate ec is a change rate of the error e with time.
Further, according to the obtained design error e, the membership function relation curve between the error change rate ec and the membership and the obtained compensation quantity UdThe membership function curve of the fuzzy controller adopts a programming language to write a fuzzy dead zone compensation algorithm so as to realize the fuzzy algorithm function of the fuzzy controller.
Further, the dead zone range | U of the electro-hydraulic proportional valve is determined through experimentsd0The determination method is that the input of the expected displacement is controlled to gradually increase from zero until the proportional valve has displacement, and the input quantity of the expected displacement at the moment is recorded, namely the input quantity is Ud0。
Further, an error threshold e is determined according to a tolerable maximum error range and a maximum error change rate range set in the closed-loop control process of the electro-hydraulic proportional valvethError change rate threshold ecth。
In another aspect, an electro-hydraulic proportional valve dead-time compensation system is provided, which utilizes the dead-time compensation algorithm as described above,
the electro-hydraulic proportional valve dead zone compensation system comprises a main control algorithm loop and a fuzzy dead zone compensation algorithm loop; the main control algorithm loop and the fuzzy dead zone compensation algorithm loop work in parallel;
the main control algorithm loop outputs a control instruction according to the input error e;
the fuzzy dead zone compensation algorithm loop outputs a dead zone compensation output U according to the electro-hydraulic proportional valve dead zone compensation algorithmC(ii) a Control command and dead zone compensation output UCAnd summing the signals to serve as the control input of the proportional valve control hydraulic cylinder system.
The invention has the technical effects that: the fuzzy dead zone compensation algorithm adopted by the invention can effectively improve the dead zone compensation precision of the proportional valve, thereby improving the control quality of a proportional valve servo system.
Drawings
FIG. 1 is a control block diagram of a proportional valve-controlled hydraulic cylinder system;
FIG. 2 is a schematic diagram of the operating characteristics of an electro-hydraulic proportional valve;
FIG. 3 is a graph illustrating membership functions for error e and error rate ec according to the present invention;
FIG. 4 is the fuzzy dead-zone compensation output U of the present inventiondA membership function curve of (1);
fig. 5 is a fuzzy control rule representation of the present invention.
Detailed Description
Example 1
The embodiment provides an electro-hydraulic proportional valve dead zone compensation algorithm, and a specific implementation method and steps include:
s101, determining the dead zone range of the proportional valve according to the experimental result, and determining the dead zone range | U of the electro-hydraulic proportional valved0Fig. 1 is a control block diagram of a proportional valve-controlled hydraulic cylinder system, as shown in fig. 1, and the present invention relates to a dead zone compensation algorithm in a dashed box in fig. 1.
Through experiments, the dead zone range | U of the electro-hydraulic proportional valve is determinedd0L. The determination method comprises the steps of controlling the input of the expected displacement to be gradually increased from zero until the proportional valve has displacement, and recording the input quantity of the expected displacement at the moment, namely Ud0。
S102, determining a rule of a variable dead zone compensation algorithm, wherein the specific rule is as follows:
giving an initial value U of dead-zone compensationd0Error threshold ethError rate of change threshold ecthWhere e is the error value between the desired displacement and the actual displacement fed back by the displacement sensor. The error change rate ec is the rate of change of the error e with time.
If | e |<ethThe positioning error e meets the precision requirement, and the compensation output quantity of the fuzzy controller is kept unchanged;
if | e |>ethAnd | ec | non-conducting<ecthWhen the ex ec is less than or equal to 0, the compensation output quantity is under-compensated, and the fuzzy controller increases the fuzzy dead zone compensation output Ud；
If | e |>ethAnd | ec | non-conducting>ecth，e×ec>0, the compensation output quantity is overcompensated, and in order to prevent the system from generating self-oscillation, the fuzzy controller calculates and reduces the fuzzy dead zone compensation output Ud。
S103, determining an error e, a fuzzy subset of an error change rate ec and a fuzzy dead zone compensation output UdThe fuzzy subset of (1);
e,ec＝[NB,NM,NS,ZO,PS,PM,PB]
Ud＝[NB,NM,NS,ZO,PS,PM,PB]
wherein, NB represents the negative big of the fuzzy variable, NM represents the negative middle of the fuzzy variable, NS represents the negative small of the fuzzy variable, ZO represents the zero value of the fuzzy variable, PS represents the positive small of the fuzzy variable, PM represents the middle of the fuzzy variable, and PB represents the positive big of the fuzzy variable.
S104, according to the error threshold ethError change rate threshold ecthDesigning a membership function relation curve among the error e, the error change rate ec and the membership, and referring to an attached figure 3. FIG. 3 is a graph illustrating a membership function curve of an error e and an error rate ec according to the present invention, wherein the abscissa is the domain of the error e and the error rate ec and the ordinate is the membership of the error e and the error rate ec; determining an error threshold e according to a tolerable maximum error range and a maximum error change rate range set in the closed-loop control process of the electro-hydraulic proportional valvethError change rate threshold ecth. If the maximum error range and the maximum error change rate range are too large or too small, the control quality and precision of the electro-hydraulic proportional valve closed-loop control do not meet the normal working requirements.
S105, according to the absolute value of the error e and the error threshold ethThe magnitude relation between the error rate ec and the absolute value of the error rate ec and the error rate threshold ecthThe magnitude relation between the two, the design of the fuzzy dead zone compensation output UdSee fig. 4. FIG. 4 is the fuzzy dead-zone compensation output U of the present inventiondFunction of degree of membership ofNumber curve, where the abscissa is the fuzzy dead-zone compensation output UdThe ordinate is the dead-zone compensation output UdDegree of membership.
S106, according to the obtained design error e, the membership function relation curve between the error change rate ec and the membership and the obtained fuzzy dead zone compensation output UdThe membership function curve of (1) and an exemplary fuzzy control rule table are shown in figure 5. Fig. 5 is a fuzzy control rule representation of the present invention.
S107, the fuzzy controller deduces fuzzy control quantity and fuzzy dead zone compensation output U by using a fuzzy control rule table according to the input of the error e and the error change rate ecdThe conversion relationship between them; fuzzy dead zone compensation output UdOutput is fuzzy dead zone compensation. In this embodiment, the design error e, the membership function relationship curve between the error change rate ec and the membership, and the compensation amount U are obtaineddThe membership function curve of the fuzzy controller adopts LABVIEW to write a fuzzy dead zone compensation algorithm, and the fuzzy algorithm function of the fuzzy controller is realized. e. ec and UdThe membership function curve can be properly adjusted according to the experimental result.
S108, compensating the initial value U according to the determined dead zoned0Fuzzy dead zone compensation output UdAnd the output voltage U of the main controllerctrlCalculating dead zone compensation output UC(ii) a And the sum of the output of the main controller and the output of the fuzzy dead zone compensation is used for controlling the proportional valve control hydraulic cylinder system. The dead zone compensation output is calculated by the formula:
UC＝sgn(Uctrl)(Ud0+Ud)
wherein U isctrlIs the output voltage of the main controller, Ud0Compensating the initial value, U, for dead zonesdIs the fuzzy dead zone compensation output of the fuzzy controller, and the dead zone compensation output is UC。
Example 2
As shown in fig. 1, the present embodiment provides an electro-hydraulic proportional valve dead zone compensation system, which utilizes the dead zone compensation algorithm as described in embodiment 1,
the electro-hydraulic proportional valve dead zone compensation system comprises a main control algorithm loop and a fuzzy dead zone compensation algorithm loop; the main control algorithm loop and the fuzzy dead zone compensation algorithm loop work in parallel;
the main control algorithm loop outputs a control instruction according to the input error e;
the fuzzy dead zone compensation algorithm loop outputs a dead zone compensation output U according to the electro-hydraulic proportional valve dead zone compensation algorithmC(ii) a Control command and dead zone compensation output UCAnd summing the signals to serve as the control input of the proportional valve control hydraulic cylinder system.

Claims (10)

1. An electro-hydraulic proportional valve dead-zone compensation algorithm, the dead-zone compensation algorithm comprising:
determining dead zone range | U of electro-hydraulic proportional valve through experimentd0|；
According to the error threshold ethError change rate threshold ecthDesigning a membership function relation curve among the error e, the error change rate ec and the membership,
according to the absolute value of the error e and the error threshold ethThe magnitude relation between the error rate ec and the absolute value of the error rate ec and the error rate threshold ecthThe magnitude relation between the two, the design of the fuzzy dead zone compensation output UdA membership function curve of (1);
according to the obtained error e, the membership function relation curve between the error change rate ec and the membership and the obtained fuzzy dead zone compensation output UdA membership function curve of the fuzzy control rule table is instantiated;
the fuzzy controller deduces fuzzy control quantity and fuzzy dead zone compensation output U by using a fuzzy control rule table according to the input of the error e and the error change rate ecdThe conversion relationship between them;
compensating the initial value U according to the determined dead zoned0Fuzzy dead zone compensation output UdAnd the output voltage U of the main controllerctrlCalculating dead zone compensation output UC(ii) a And the sum of the output of the main controller and the output of the fuzzy dead zone compensation is used for closed-loop control of the proportional valve control hydraulic cylinder system.
2. The dead-time compensation algorithm of claim 1, wherein the dead-time compensation output is calculated by the formula:
UC＝sgn(Uctrl)(Ud0+Ud)
wherein U isctrlIs the output voltage of the main controller, Ud0Compensating the initial value, U, for dead zonesdFor fuzzy dead-zone compensation output of the fuzzy controller, UCCompensating output for dead zone; sgn is the sign operator.
3. The dead-band compensation algorithm of claim 2, wherein the fuzzy dead-band compensation output U is designeddThe membership function curve of (1):
if | e |<ethThe positioning error e meets the precision requirement, and the compensation output quantity of the fuzzy controller is kept unchanged;
if | e |>ethAnd | ec | non-conducting<ecthWhen the output quantity of compensation is under-compensation, the fuzzy controller calculates and increases the output U of fuzzy dead zone compensationd；
If | e |>ethAnd | ec | non-conducting>ecth，e×ec>0, the compensation output quantity is overcompensated, and in order to prevent the system from generating self-oscillation, the fuzzy controller calculates and reduces the fuzzy dead zone compensation output Ud。
4. The dead-zone compensation algorithm of claim 3, wherein an error e, a fuzzy subset of the error rate of change ec, and a fuzzy dead-zone compensation output Uc are determineddThe fuzzy subset of (1);
e,ec＝[NB,NM,NS,ZO,PS,PM,PB]
Ud＝[NB,NM,NS,ZO,PS,PM,PB]
wherein, NB represents the negative big of the fuzzy variable, NM represents the negative middle of the fuzzy variable, NS represents the negative small of the fuzzy variable, ZO represents the zero value of the fuzzy variable, PS represents the positive small of the fuzzy variable, PM represents the middle of the fuzzy variable, and PB represents the positive big of the fuzzy variable.
5. The dead band compensation algorithm of claim 1, wherein e is an error value between a desired displacement of the proportional valve controlled hydraulic cylinder system and an actual displacement fed back by the displacement sensor.
6. The dead-zone compensation algorithm of claim 1 wherein the error rate of change ec is the rate of change of the error e over time.
7. The dead-zone compensation algorithm of claim 1, wherein the compensation amount U is obtained according to the obtained design error e, a membership function relationship curve between the error change rate ec and the membership, and the obtained compensation amount UdThe membership function curve of the fuzzy controller adopts a programming language to write a fuzzy dead zone compensation algorithm so as to realize the fuzzy algorithm function of the fuzzy controller.
8. The dead-zone compensation algorithm of claim 1, wherein the dead-zone range | U of the electro-hydraulic proportional valve is determined experimentallyd0The determination method is that the input of the expected displacement is controlled to gradually increase from zero until the proportional valve has displacement, and the input quantity of the expected displacement at the moment is recorded, namely the input quantity is Ud0。
9. The dead-zone compensation algorithm of claim 1,
determining an error threshold e according to a tolerable maximum error range and a maximum error change rate range set in the closed-loop control process of the electro-hydraulic proportional valvethError change rate threshold ecth。
10. An electro-hydraulic proportional valve dead-zone compensation system using the dead-zone compensation algorithm of any one of claims 1 to 9,
the electro-hydraulic proportional valve dead zone compensation system comprises a main control algorithm loop and a fuzzy dead zone compensation algorithm loop; the main control algorithm loop and the fuzzy dead zone compensation algorithm loop work in parallel;
the main control algorithm loop outputs a control instruction according to the input error e;
the fuzzy dead zone compensation algorithm loop outputs a dead zone compensation output U according to the electro-hydraulic proportional valve dead zone compensation algorithmC(ii) a Control command and dead zone compensation output UCAnd summing the signals to serve as the control input of the proportional valve control hydraulic cylinder system.
CN202010909357.7A 2020-09-02 2020-09-02 Electro-hydraulic proportional valve dead zone compensation algorithm and compensation system Pending CN112068430A (en)

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Application publication date: 20201211