CN114879501A - Electro-hydraulic proportional servo valve control method considering time-varying parameter uncertainty - Google Patents

Electro-hydraulic proportional servo valve control method considering time-varying parameter uncertainty Download PDF

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CN114879501A
CN114879501A CN202210538766.XA CN202210538766A CN114879501A CN 114879501 A CN114879501 A CN 114879501A CN 202210538766 A CN202210538766 A CN 202210538766A CN 114879501 A CN114879501 A CN 114879501A
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servo valve
proportional servo
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姚建勇
杨晓伟
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Nanjing University of Science and Technology
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Abstract

The invention discloses a time-varying parameter uncertainty considered electro-hydraulic proportional servo valve shaft control system self-adaptive dynamic surface control method, which is obtained by fusing time-varying parameter self-adaptive control and dynamic surface control and performing feedforward cancellation on a model. Aiming at the problem of valve control of the electro-hydraulic proportional servo valve considering uncertainty of time-varying parameters, the invention can ensure the active elimination of the uncertainty of the time-varying parameters of the system, improve the capability of the system for resisting the uncertainty of the parameters, avoid the problem of differential explosion in the traditional backstepping control of the electro-hydraulic system, reduce the influence of measurement noise on the control precision and realize high-precision tracking performance.

Description

Electro-hydraulic proportional servo valve control method considering time-varying parameter uncertainty
Technical Field
The invention relates to the technical field of electromechanical servo control, in particular to an electro-hydraulic proportional servo valve control method (ADSC) considering time-varying parameter uncertainty.
Background
The electro-hydraulic proportional servo valve shaft control system plays a very important role in the fields of robots, heavy machinery, high-performance loading test equipment and the like by virtue of the characteristics of high power density, large force/torque output, quick dynamic response and the like. The electro-hydraulic proportional servo valve control system is a typical nonlinear system and comprises a plurality of nonlinear characteristics and modeling uncertainty. The nonlinear characteristics comprise input nonlinearity such as magnetic hysteresis and saturation, flow pressure nonlinearity of a proportional servo valve, friction nonlinearity and the like, the modeling uncertainty comprises parameter uncertainty and uncertainty nonlinearity, wherein the parameter uncertainty mainly comprises load quality, viscous friction coefficient of an actuator, leakage coefficient, servo valve flow gain, hydraulic oil elastic modulus and the like, and the uncertainty nonlinearity mainly comprises unmodeled friction dynamics, system high-order dynamics, external interference, unmodeled leakage and the like. When the electro-hydraulic proportional servo valve control system is developed towards high precision and high frequency response, the influence of the nonlinear characteristics presented by the system on the system performance is more obvious, and the existence of modeling uncertainty can cause the controller designed by a system nominal model to be unstable or reduced, so the nonlinear characteristics and the modeling uncertainty of the electro-hydraulic proportional servo valve control system are important factors for limiting the improvement of the system performance. With the continuous progress of the technical level in the industrial and defense fields, the traditional controller designed based on the traditional linear theory can not meet the high-performance requirement of the system gradually, so that a more advanced nonlinear control strategy must be researched aiming at the nonlinear characteristic in the electro-hydraulic proportional servo valve shaft control system.
Aiming at the problem of nonlinear control of an electro-hydraulic proportional servo valve control system, a plurality of methods are proposed in succession. The self-adaptive control method is an effective method for processing the uncertainty problem of parameters, and can obtain the steady-state performance of asymptotic tracking, but the uncertainty nonlinearity such as external load interference is not good at all, the system can be unstable when the uncertainty nonlinearity is too large, and the actual electro-hydraulic proportional servo valve control system has uncertainty nonlinearity, so that the self-adaptive control method cannot obtain the high-precision control performance in practical application; as a robust control method, classical sliding mode control can effectively process any bounded modeling uncertainty and obtain steady-state performance of asymptotic tracking, but a discontinuous controller designed by classical sliding mode control easily causes the flutter problem of a sliding mode surface, so that the tracking performance of a system is deteriorated; in order to solve the problems of parameter uncertainty and uncertainty nonlinearity simultaneously, an adaptive robust control method is provided, the control method can enable a system to obtain determined transient and steady-state performances under the condition that two modeling uncertainties exist simultaneously, if high-precision tracking performance is obtained, a tracking error must be reduced by improving feedback gain, and due to the existence of measurement noise, the gain is excessively obtained, so that high-gain feedback is caused, the jitter of control input is caused, the control performance is further deteriorated, and even the system is unstable.
Disclosure of Invention
The invention provides an electro-hydraulic proportional servo valve shaft control method considering time-varying parameter uncertainty, which can ensure the active elimination of the time-varying parameter uncertainty of a system, improve the parameter uncertainty resistance of the system, avoid the problem of differential explosion in the traditional backstepping control of the electro-hydraulic system, reduce the influence of measurement noise on the control precision and realize high-precision tracking performance.
The technical solution for realizing the purpose of the invention is as follows: an electro-hydraulic proportional servo valve control method considering uncertainty of time-varying parameters comprises the following steps:
step 1, establishing a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and turning to step 2;
step 2, designing a self-adaptive dynamic surface controller considering uncertainty of time-varying parameters based on a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and turning to step 3;
and 3, performing stability verification of the adaptive dynamic surface controller by using the Lyapunov stability theory in consideration of time-varying parameter uncertainty to obtain a result that the tracking error of the system is gradually stable.
Compared with the prior art, the invention has the following remarkable advantages: (1) the uncertainty of system time-varying parameters and the active compensation of unknown disturbance are realized, and the anti-interference capability is strong; (2) the problem of differential explosion in the traditional backstepping control of the electro-hydraulic system is avoided, the influence of measurement noise on the control precision is reduced, the high-precision tracking performance is realized, and the effectiveness of the simulation result is verified.
Drawings
FIG. 1 is a schematic diagram of the principle of the electro-hydraulic proportional servo valve control method considering uncertainty of time-varying parameters.
FIG. 2 is a schematic diagram of an electro-hydraulic proportional servo valve control system according to the present invention.
FIG. 3 is a graph of the trace process of the system output to the desired command under the action of the ADSC controller designed by the present invention.
FIG. 4 is a graph showing the tracking error of the ADSC controller system over time.
FIG. 5 is a graph comparing tracking error of the ADSC controller and a conventional PID controller.
FIG. 6 is a control input graph of the system under the action of the ADSC controller designed by the present invention.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
With reference to fig. 1 and 2, the electro-hydraulic proportional servo valve control method considering uncertainty of time-varying parameters of the invention comprises the following steps:
step 1, establishing a mathematical model of an electro-hydraulic proportional servo valve position shaft control system.
Step 1-1, the electro-hydraulic proportional servo valve position shaft control system is applied to linear motion of large-scale industrial heavy-load mechanical equipment, wherein a load is fixedly connected with a piston rod on a hydraulic oil cylinder, and the electro-hydraulic proportional servo valve controls the piston rod on the hydraulic oil cylinder to move so as to drive the load to move.
According to Newton's second law, the force balance equation of the electro-hydraulic proportional servo valve position shaft control system is as follows:
Figure BDA0003649426410000031
formula (1), m represents the mass of the load, y represents the displacement of the piston rod of the hydraulic oil cylinder,
Figure BDA0003649426410000032
the speed of a piston rod of the hydraulic oil cylinder is shown,
Figure BDA0003649426410000033
representing the acceleration of the piston rod of the hydraulic cylinder, A representing the effective active area of the piston of the hydraulic cylinder, P 1 Indicating the oil pressure in the inlet chamber of the hydraulic cylinder, P 2 Representing the oil pressure of an oil outlet cavity of the hydraulic oil cylinder, B representing the viscous damping coefficient of the hydraulic cylinder, A f The coulomb friction amplitude of the hydraulic cylinder is shown,
Figure BDA0003649426410000034
representing the approximate shape function of the Coulomb friction of the hydraulic cylinder, d 1 (t) represents unmodeled disturbance of the system machinery, and t represents time.
Then equation (1) is rewritten as:
Figure BDA0003649426410000035
in the position shaft control system of the electro-hydraulic proportional servo valve, if oil leakage of an oil cylinder is ignored, the pressure dynamic equation is as follows:
Figure BDA0003649426410000036
in the formula (3), beta e Representing the effective modulus of elasticity, C, of the oil t The oil pressure difference P of oil inlet and outlet chambers at two sides of the oil cylinder is expressed by the leakage coefficient in the hydraulic cylinder L =P 1 -P 2 Control volume V of oil inlet chamber 1 =V 01 + Ay, control volume V of oil outlet chamber 2 =V 02 -Ay,V 01 Indicates the initial volume of the oil inlet chamber, V 02 Showing the initial volume, Q, of the oil chamber 1 Indicating the flow of the inlet chamber, Q 2 Shows the flow of the oil chamber, q 1 Represents P 1 Unmodeled interference of q 2 Represents P 2 Is measured in a non-modeled interference of (c),
Figure BDA0003649426410000041
represents P 1 The first derivative of (a) is,
Figure BDA0003649426410000042
represents P 2 The first derivative of (a).
Q 1 、Q 2 Respectively proportional to the displacement x of the spool of the electrohydraulic servo valve v The following relationships exist:
Figure BDA0003649426410000043
wherein, the valve coefficient of the electro-hydraulic proportional servo valve
Figure BDA0003649426410000044
C d Indicating the flow coefficient, w, of an electro-hydraulic proportional servo valve 0 Showing the area gradient of a valve core of the electro-hydraulic proportional servo valve, wherein rho shows the density of oil liquid and P s Indicating the supply pressure, P r Represents the return pressure, s (-) represents a function of the intermediate variable, defined as:
Figure BDA0003649426410000045
neglecting the dynamic of the valve core of the electro-hydraulic proportional servo valve, assuming the control input u acting on the valve core and the valve core displacement x v Proportional relationship, i.e. satisfying x v =k i u, wherein k i Since the voltage-spool displacement gain coefficient is expressed, equation (4) is rewritten as:
Figure BDA0003649426410000046
formula (6), intermediate variable k u =k q k i Intermediate variables
Figure BDA0003649426410000047
Intermediate variables
Figure BDA0003649426410000048
Step 1-2, defining a state variable:
Figure BDA0003649426410000049
wherein the intermediate variable x 1 Y, intermediate variables
Figure BDA00036494264100000410
Intermediate variable x 3 =(AP 1 -AP 2 ) /m, system unknown time-varying parameter Θ 1 =[θ 123 ] T =[B,A f ,D 1 ] T Wherein the intermediate variable θ 1 B, intermediate variable θ 2 =A f Intermediate variable θ 3 =D 1 The system unknown time-varying parameter Θ 2 =D 2 Then, equation (2) is converted into an equation of state:
Figure BDA00036494264100000411
the compound of the formula (7),
Figure BDA00036494264100000412
denotes x 1 The first derivative of (a) is,
Figure BDA00036494264100000413
denotes x 2 The first derivative of (a) is,
Figure BDA00036494264100000414
denotes x 3 First derivative, intermediate variable of
Figure BDA00036494264100000415
Intermediate variables
Figure BDA00036494264100000416
Intermediate variable D 1 =d 1 (t)/m, intermediate variable
Figure BDA0003649426410000051
Intermediate variables
Figure BDA0003649426410000052
Intermediate variables
Figure BDA0003649426410000053
Intermediate variables
Figure BDA0003649426410000054
To facilitate the design of the controller and unknown dynamic observer, the following assumptions are made:
assume that 1: system expected tracking position instruction x d Is second order continuous and the system expects that the position command, velocity command, and acceleration command are bounded.
Assume 2: system unknown time varying parameter theta 1 And theta 2 Satisfies the following conditions:
||Θ 1 ||≤δ 1 ,||Θ 2 ||≤δ 2 (8)
formula (8), δ 1 And delta 2 Are all unknown positive constants.
And (5) transferring to the step 2.
Step 2, designing a self-adaptive dynamic surface controller considering uncertainty of time-varying parameters based on a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and specifically comprising the following steps:
step 2-1, defining the tracking error z of the system for designing the controller 1 =x 1 -x d ,x d Is a system expected tracking position instruction, and the following nonlinear filter is designed:
Figure BDA0003649426410000055
equation (9), filter gain τ 1 >0,α 1 Denotes x 2 Virtual control of alpha 1f Denotes alpha 1 Of the filtered signal, alpha 1f And x 2 Error z of 2 =x 21f ,α 1 Filter error e 1 =α 1f1 Gain l 1 > 0 represents
Figure BDA0003649426410000056
Upper bound of (a) 1 (t) represents a constant positive function, and satisfies
Figure BDA0003649426410000057
Wherein, v represents an integral variable,
Figure BDA0003649426410000058
a constant that is constant and positive is represented,
Figure BDA0003649426410000059
denotes alpha 1 The first derivative of (a) is,
Figure BDA00036494264100000510
denotes alpha 1f The first derivative of (a).
To z 1 And (5) obtaining a derivative:
Figure BDA00036494264100000511
designing virtual control alpha 1 Comprises the following steps:
Figure BDA00036494264100000512
wherein,
Figure BDA0003649426410000061
denotes x d First derivative, gain k 1 If greater than 0, then
Figure BDA0003649426410000062
Step 2-2, for z 2 And (5) obtaining a derivative:
Figure BDA0003649426410000063
the following nonlinear filter is designed:
Figure BDA0003649426410000064
equation (14), filter gain τ 2 >0,α 2 Denotes x 3 Virtual control of,α 2f Denotes alpha 2 Of the filtered signal, alpha 2f And x 3 Error z of 3 =x 32f ,α 2 Filter error e 2 =α 2f2 Gain l 2 > 0 represents
Figure BDA0003649426410000065
Upper bound of (a) ("σ 2 (t) represents a constant positive function, and satisfies
Figure BDA0003649426410000066
Wherein, v represents an integral variable,
Figure BDA0003649426410000067
a constant that is constant and positive is represented,
Figure BDA0003649426410000068
denotes alpha 2 The first derivative of (a) is,
Figure BDA0003649426410000069
denotes alpha 2f The first derivative of (a).
Defining intermediate variables
Figure BDA00036494264100000618
Designing virtual control alpha 2 Comprises the following steps:
Figure BDA00036494264100000610
formula (15), χ 1 The intermediate variable is represented by a number of variables,
Figure BDA00036494264100000611
to represent
Figure BDA00036494264100000619
Estimate of (2), gain k 2 > 0, intermediate variable
Figure BDA00036494264100000612
Figure BDA00036494264100000613
Law of update of
Figure BDA00036494264100000614
Is composed of
Figure BDA00036494264100000615
Formula (16), gain μ 1 >0。
Substituting formula (15) for formula (13) to obtain:
Figure BDA00036494264100000616
step 2-3, for z 3 And (5) obtaining a derivative:
Figure BDA00036494264100000617
defining intermediate variables
Figure BDA00036494264100000711
According to equation (18), the control input of the spool, i.e., the adaptive dynamic surface controller u designed to take into account the uncertainty of the time-varying parameters, is:
Figure BDA0003649426410000071
formula (19), gain k 3 > 0, intermediate variable
Figure BDA0003649426410000072
χ 2 The intermediate variable is represented by a number of variables,
Figure BDA0003649426410000073
to represent
Figure BDA00036494264100000712
Is determined by the estimated value of (c),
Figure BDA0003649426410000074
law of update
Figure BDA0003649426410000075
Is composed of
Figure BDA0003649426410000076
Formula (20), gain μ 2 >0。
Substituting formula (19) into formula (18):
Figure BDA0003649426410000077
and (5) turning to the step 3.
Step 3, the stability of the adaptive dynamic surface controller is proved by using the Lyapunov stability theory and considering the uncertainty of the time-varying parameters, and a result that the tracking error of the system is gradually stable is obtained, which is concretely as follows:
the lyapunov function is defined as follows:
Figure BDA0003649426410000078
wherein the intermediate variable
Figure BDA0003649426410000079
Intermediate variables
Figure BDA00036494264100000710
Derivation of equation (22) and substitution of equations (9), (12), (14), (16), (17), (20), and (21) can result:
Figure BDA0003649426410000081
in view of
Figure BDA0003649426410000082
And
Figure BDA0003649426410000083
the expression can be obtained:
Figure BDA0003649426410000084
it is noted that
Figure BDA0003649426410000085
Can obtain the product
Figure BDA0003649426410000086
By substituting formula (24) with formula (25) and formula (26), the compound can be obtained
Figure BDA0003649426410000087
Defining the intermediate variables z and Λ as:
z=[z 1 ;z 2 ;z 3 ;ε 1 ;ε 2 ] (28)
Figure BDA0003649426410000091
equation (29), intermediate variable Λ 1 And Λ 2 Are respectively as
Figure BDA0003649426410000092
By adjusting the gain k 1 、k 2 、k 3 And a filter gain τ 1 、τ 2 If the symmetric matrix Λ is a positive definite matrix, then:
Figure BDA0003649426410000093
formula (31), intermediate variable Φ ═ z T Λz。
Integrating the two sides of equation (31) to obtain:
Figure BDA0003649426410000094
from equation (32), V is bounded and Φ is bounded by an integral. It follows that all signals of the system are bounded. Thus, Φ is consistently continuous. According to the Barbalt theorem, the tracking error z is obtained when the time tends to be infinite 1 Tending towards 0.
It is therefore concluded that: by adjusting the gain k 1 、k 2 、k 3 And a filter gain τ 1 、τ 2 The adaptive dynamic surface controller designed for the electro-hydraulic proportional servo valve position shaft control system and considering time-varying parameter uncertainty can enable the system to obtain a result that a tracking error gradually converges to 0, and the schematic diagram of the principle of the adaptive dynamic surface controller of the electro-hydraulic proportional servo valve position shaft control system and considering the time-varying parameter uncertainty is shown in fig. 1.
Examples
In order to examine the performance of the designed controller, the physical parameters of the electro-hydraulic proportional servo valve position shaft control system in the simulation are shown in table 1:
TABLE 1 physical parameters of the System
Physical parameters Numerical value Physical parameters Numerical value
A(m 2 ) 2×10 -4 β e (Pa) 2×10 8
m(kg) 40 B(N·s/m) 80
C t (m 5 /(N·s)) 7×10 -12 k u (m/V) 4×10 -8
V 01 (m 3 ) 1×10 -3 V 02 (m 3 ) 1×10 -3
P s (MPa) 7 P r (MPa) 0
A f (N·s/m) 10
The expected instruction for a given system is
Figure BDA0003649426410000101
Coulomb friction shape function of S f (x 2 )=2arctan(1000x 2 )/π。
The following controller comparisons were taken in the simulation:
electro-hydraulic proportional servo valve position shaft controller (UDORC) taking into account unknown dynamic compensation of the system: gain k is taken 1 =10,k 2 =1,k 3 =1,μ 1 =20,μ 2 =20,τ 1 =100,τ 2 =1000,l 1 =l 2 =1。
A PID controller: the PID controller parameter selection steps are as follows: firstly, a set of controller parameters is obtained through a PID parameter self-tuning function in Matlab under the condition of neglecting the nonlinear dynamics of an electro-hydraulic proportional servo valve shaft control system, and then the obtained self-tuning parameters are subjected to fine tuning after the nonlinear dynamics of the system is added, so that the system obtains the optimal tracking performance. The selected controller parameter is k P =10,k I =1,k D =1。
The expected command of the system, the ADSC controller tracking error compared to the PID controller tracking error are shown in FIGS. 3, 4 and 5, respectively. As can be seen from FIG. 4, under the action of the ADSC controller, the position output of the proportional servo valve axis control system has high tracking precision to the command, and the amplitude of the steady-state tracking error is about 5 × 10 -4 And m is selected. It can be seen from the comparison of the tracking errors of the two controllers in fig. 5 that the tracking error of the ADSC controller proposed by the present invention is much smaller than that of the PID controller, and the tracking performance is more excellent.
FIG. 6 is a graph of the control input of the electro-hydraulic proportional servo valve control system changing with time under the action of the ADSC controller, and it can be seen from the graph that the obtained control input is a continuous signal, which is more beneficial to be implemented in practical application.

Claims (4)

1. An electro-hydraulic proportional servo valve control method considering uncertainty of time-varying parameters is characterized by comprising the following steps of:
step 1, establishing a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and turning to step 2;
step 2, designing a self-adaptive dynamic surface controller considering uncertainty of time-varying parameters based on a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and turning to step 3;
and 3, performing stability verification of the adaptive dynamic surface controller by using the Lyapunov stability theory in consideration of time-varying parameter uncertainty to obtain a result that the tracking error of the system is gradually stable.
2. The electro-hydraulic proportional servo valve shaft control method considering uncertainty of time-varying parameters as claimed in claim 1, wherein in step 1, a mathematical model of an electro-hydraulic proportional servo valve position shaft control system is established, specifically as follows:
step 1-1, the electro-hydraulic proportional servo valve position shaft control system is applied to linear motion of large-scale industrial heavy-load mechanical equipment, wherein a load is fixedly connected with a piston rod on a hydraulic oil cylinder, and the electro-hydraulic proportional servo valve controls the piston rod on the hydraulic oil cylinder to move so as to drive the load to move;
according to Newton's second law, the force balance equation of the electro-hydraulic proportional servo valve position shaft control system is as follows:
Figure FDA0003649426400000011
formula (1), m represents the mass of the load, y represents the displacement of the piston rod of the hydraulic oil cylinder,
Figure FDA0003649426400000012
the speed of a piston rod of the hydraulic oil cylinder is shown,
Figure FDA0003649426400000013
representing the acceleration of the piston rod of the hydraulic cylinder, A representing the effective active area of the piston of the hydraulic cylinder, P 1 Indicating the oil pressure in the inlet chamber of the hydraulic cylinder, P 2 Representing the oil pressure of an oil outlet cavity of the hydraulic oil cylinder, B representing the viscous damping coefficient of the hydraulic cylinder, A f The coulomb friction amplitude of the hydraulic cylinder is shown,
Figure FDA0003649426400000016
representing the approximate shape function of the Coulomb friction of the cylinder, d 1 (t) represents unmodeled disturbance of the system machinery, t represents time;
then equation (1) is rewritten as:
Figure FDA0003649426400000014
in the position shaft control system of the electro-hydraulic proportional servo valve, if oil leakage of an oil cylinder is ignored, the pressure dynamic equation is as follows:
Figure FDA0003649426400000015
in the formula (3), beta e Representing the effective modulus of elasticity, C, of the oil t The oil pressure difference P of oil inlet and outlet chambers at two sides of the oil cylinder is expressed by the leakage coefficient in the hydraulic cylinder L =P 1 -P 2 Control volume V of oil inlet chamber 1 =V 01 + Ay, control volume V of oil outlet chamber 2 =V 02 -Ay,V 01 Indicates the initial volume of the oil inlet chamber, V 02 Showing the initial volume, Q, of the oil chamber 1 Indicating the flow of the inlet chamber, Q 2 Shows the flow of the oil chamber, q 1 Represents P 1 Unmodeled interference of q 2 Represents P 2 Is measured in a non-modeled interference of (c),
Figure FDA0003649426400000021
represents P 1 The first derivative of (a) is,
Figure FDA0003649426400000022
represents P 2 The first derivative of (a);
Q 1 、Q 2 respectively proportional to the displacement x of the spool of the electrohydraulic servo valve v The following relationships exist:
Figure FDA0003649426400000023
wherein, the valve coefficient of the electro-hydraulic proportional servo valve
Figure FDA0003649426400000024
C d Indicating the flow coefficient, w, of an electro-hydraulic proportional servo valve 0 Showing the area gradient of a valve core of the electro-hydraulic proportional servo valve, wherein rho shows the density of oil liquid and P s Indicating the supply pressure, P r Represents the return pressure, s (-) represents a function of the intermediate variable, defined as:
Figure FDA0003649426400000025
neglecting the dynamic of the valve core of the electro-hydraulic proportional servo valve, assuming the control input u acting on the valve core and the valve core displacement x v Proportional relationship, i.e. satisfying x v =k i u, wherein k i Since the voltage-spool displacement gain coefficient is expressed, equation (4) is rewritten as:
Figure FDA0003649426400000026
formula (6), intermediate variable k u =k q k i Intermediate variables
Figure FDA0003649426400000027
Intermediate variables
Figure FDA0003649426400000028
Step 1-2, defining a state variable:
Figure FDA0003649426400000029
wherein the intermediate variable x 1 Y, intermediate variables
Figure FDA00036494264000000210
Intermediate variable x 3 =(AP 1 -AP 2 ) /m, system unknown time-varying parameter Θ 1 =[θ 123 ] T =[B,A f ,D 1 ] T Wherein the intermediate variable θ 1 B, intermediate variable θ 2 =A f Intermediate variable θ 3 =D 1 The system unknown time-varying parameter Θ 2 =D 2 Then, equation (2) is converted into an equation of state:
Figure FDA0003649426400000031
in the formula (7),
Figure FDA0003649426400000032
denotes x 1 The first derivative of (a) is,
Figure FDA0003649426400000033
denotes x 2 The first derivative of (a) is,
Figure FDA0003649426400000034
denotes x 3 First derivative, intermediate variable of
Figure FDA0003649426400000035
Intermediate variables
Figure FDA0003649426400000036
Intermediate variable D 1 =d 1 (t)/m, intermediate variable
Figure FDA0003649426400000037
Intermediate variables
Figure FDA0003649426400000038
Intermediate variables
Figure FDA0003649426400000039
Intermediate variables
Figure FDA00036494264000000310
To facilitate the design of the controller and unknown dynamic observer, the following assumptions are made:
assume that 1: system expected tracking position instruction x d Is second order continuous and the system expects that the position command, the speed command and the acceleration command are bounded;
assume 2: system unknown time varying parameter theta 1 And theta 2 Satisfies the following conditions:
||Θ 1 ||≤δ 1 ,||Θ 2 ||≤δ 2 (8)
formula (8), δ 1 And delta 2 Are all unknown positive constants;
and (5) transferring to the step 2.
3. The electro-hydraulic proportional servo valve shaft control method considering the uncertainty of the time-varying parameter as claimed in claim 2, wherein in step 2, an adaptive dynamic surface controller considering the uncertainty of the time-varying parameter is designed based on a mathematical model of an electro-hydraulic proportional servo valve position shaft control system, and the specific steps are as follows:
step 2-1, defining the tracking error z of the system for designing the controller 1 =x 1 -x d ,x d Is a system expected tracking position instruction, and the following nonlinear filter is designed:
Figure FDA00036494264000000311
equation (9), filter gain τ 1 >0,α 1 Denotes x 2 Virtual control of alpha 1f Denotes alpha 1 Of the filtered signal, alpha 1f And x 2 Error z of 2 =x 21f ,α 1 Filter error e 1 =α 1f1 Gain l 1 > 0 represents
Figure FDA00036494264000000312
Upper bound of (a) 1 (t) represents a constant positive function, and satisfies
Figure FDA00036494264000000313
Wherein, v represents an integral variable,
Figure FDA0003649426400000041
a constant that is constant and positive is represented,
Figure FDA0003649426400000042
denotes alpha 1 The first derivative of (a) is,
Figure FDA0003649426400000043
denotes alpha 1f The first derivative of (a);
to z 1 And (5) obtaining a derivative:
Figure FDA0003649426400000044
designing virtual control alpha 1 Comprises the following steps:
Figure FDA0003649426400000045
wherein,
Figure FDA0003649426400000046
denotes x d First derivative, gain k 1 If greater than 0, then
Figure FDA0003649426400000047
Step 2-2, for z 2 And (5) obtaining a derivative:
Figure FDA0003649426400000048
the following nonlinear filter is designed:
Figure FDA0003649426400000049
equation (14), filter gain τ 2 >0,α 2 Denotes x 3 Virtual control of alpha 2f Denotes alpha 2 Of the filtered signal, alpha 2f And x 3 Error z of 3 =x 32f ,α 2 Filter error e 2 =α 2f2 Gain l 2 > 0 represents
Figure FDA00036494264000000410
Upper bound of (a) 2 (t) represents a constant positive function, and satisfies
Figure FDA00036494264000000411
Wherein, v represents an integral variable,
Figure FDA00036494264000000412
a constant that is constant and positive is represented,
Figure FDA00036494264000000413
denotes alpha 2 The first derivative of (a) is,
Figure FDA00036494264000000414
denotes alpha 2f The first derivative of (a);
defining intermediate variables
Figure FDA00036494264000000422
Designing virtual control alpha 2 Comprises the following steps:
Figure FDA00036494264000000415
formula (15), χ 1 The intermediate variable is represented by a number of variables,
Figure FDA00036494264000000416
to represent
Figure FDA00036494264000000421
Estimate of (2), gain k 2 > 0, intermediate variable
Figure FDA00036494264000000417
Figure FDA00036494264000000418
Law of update of
Figure FDA00036494264000000419
Is composed of
Figure FDA00036494264000000420
Formula (16), gain μ 1 >0;
Substituting formula (15) for formula (13) to obtain:
Figure FDA0003649426400000051
step 2-3, for z 3 Obtaining a derivative:
Figure FDA0003649426400000052
defining intermediate variables
Figure FDA00036494264000000513
According to equation (18), the control input of the spool, i.e., the adaptive dynamic surface controller u designed to take into account the uncertainty of the time-varying parameters, is:
Figure FDA0003649426400000053
formula (19), gain k 3 > 0, intermediate variables
Figure FDA0003649426400000054
χ 2 The intermediate variable is represented by a number of variables,
Figure FDA0003649426400000055
to represent
Figure FDA00036494264000000514
Is determined by the estimated value of (c),
Figure FDA0003649426400000056
law of update
Figure FDA0003649426400000057
Is composed of
Figure FDA0003649426400000058
Formula (20), gain μ 2 >0;
Substituting formula (19) into formula (18):
Figure FDA0003649426400000059
and (5) turning to the step 3.
4. The electro-hydraulic proportional servo valve shaft control method considering the uncertainty of the time-varying parameter as claimed in claim 3, wherein the stability of the adaptive dynamic surface controller considering the uncertainty of the time-varying parameter is proved by applying the Lyapunov stability theory in step 3, so as to obtain a result that the tracking error of the system is gradually stabilized, specifically as follows:
the lyapunov function is defined as follows:
Figure FDA00036494264000000510
wherein the intermediate variable
Figure FDA00036494264000000511
Intermediate variables
Figure FDA00036494264000000512
And (3) carrying out stability verification by using the Lyapunov stability theory to obtain a result of gradual stabilization of the tracking error of the system.
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CN118192225A (en) * 2024-02-26 2024-06-14 南京理工大学 Electrohydraulic proportional servo valve self-learning gain position axis control method
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CN118192225A (en) * 2024-02-26 2024-06-14 南京理工大学 Electrohydraulic proportional servo valve self-learning gain position axis control method
CN118068714A (en) * 2024-03-04 2024-05-24 南京理工大学 Intelligent valve core displacement control method considering unknown hydrodynamic force compensation
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