A preset performance output feedback control method for an electro-hydraulic servo system based on disturbance compensation and full-state constraints

Abstract

The present invention discloses a method for controlling a preset performance output feedback of an electro-hydraulic servo system based on interference compensation and full-state constraints in the technical field of electro-hydraulic servo systems, comprising the following steps: establishing a double-rod hydraulic cylinder servo system model; designing a preset performance controller of the electro-hydraulic servo system based on model uncertainty compensation and full-state constraints; adjusting a parameter u based on a control law; the preset performance output feedback controller of the electro-hydraulic servo system based on an obstacle Lyapunov function designed by the present invention estimates system interference and unknown states and uses them for controller design, which can effectively improve the practicality of the electro-hydraulic servo system and greatly reduce the feedback gain of the system; the tracking error and state of the system are constrained by the design of a preset performance function and an obstacle Lyapunov function, thereby ensuring that the position output of the double-rod hydraulic cylinder servo system can accurately track the desired position instruction.

Description

Technical Field

[0001] The present invention relates to the technical field of electro-hydraulic servo systems, and in particular to a preset performance output feedback control method of an electro-hydraulic servo system based on disturbance compensation and full-state constraints. Background Art

[0002] The electro-hydraulic servo system refers to a hydraulic control system with servo elements (servo valves or servo pumps) as the control core. It is usually composed of a command device, a controller, an amplifier, a hydraulic source, a servo element, an actuator, a feedback sensor and a load. The electro-hydraulic servo system, also known as a tracking system, is an automatic control system in which the actuator can automatically, quickly and accurately act according to the changing rules of the input signal. At the same time, the system also plays the role of amplifying the signal power. This system composed of electro-hydraulic elements is called a hydraulic servo system.

[0003] Electro-hydraulic servo systems have the advantages of high control accuracy, large output power, flexible signal processing, and easy feedback of various parameters. Therefore, they have been widely used in various fields of national defense and industry. However, with the progress of the times, the performance requirements of hydraulic systems are getting higher and higher, and the influencing factors that need to be considered are also increasing, resulting in the extremely complex design of high-performance controllers. In order to improve the tracking performance of electro-hydraulic systems, designers have studied many advanced nonlinear controllers, such as robust adaptive control, adaptive robust control, disturbance compensation control, sliding mode control, etc. Although they have achieved excellent tracking performance, these controls only focus on steady-state control errors, and there is no intuitive display and quantitative control of transient tracking errors and system operation status. In addition, most controllers need to know all the state information of the system, which is almost impossible for actual hydraulic application systems. Because of structural, space, reliability, and economic considerations, actual systems often only install displacement sensors for measuring position signals. How to obtain controllable transient errors and high-precision steady-state tracking while constraining the state of the system when only the position state information is known is an important issue.

[0004] Therefore, it is urgent to design a preset performance output feedback control method for the electro-hydraulic servo system based on disturbance compensation and full-state constraints. Summary of the invention

[0005] The object of the present invention is to provide a preset performance output feedback control method of an electro-hydraulic servo system based on disturbance compensation and full-state constraints, so as to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for output feedback control of a preset performance of an electro-hydraulic servo system based on disturbance compensation and full-state constraints, characterized in that it comprises the following steps:

[0007] S1: Establish a double-rod hydraulic cylinder servo system model;

[0008] S2: Design a preset performance controller for an electro-hydraulic servo system based on model uncertainty compensation and full-state constraints;

[0009] S3: Adjustment of parameters based on control law u.

[0010] Furthermore, in the above-mentioned preset performance output feedback control method of the electro-hydraulic servo system based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S1 are: according to Newton's second law, the dynamic model equation of the inertial load of the double-rod hydraulic cylinder is:

[0011]

[0012] Where: y is the load displacement, m is the inertial load, P L =P1-P2 is the load driving pressure, P1 and P2 are the pressures in the two chambers of the hydraulic cylinder, A is the effective working area of ​​the piston rod, and B represents the viscous friction coefficient. represents other unmodeled disturbances, such as nonlinear friction, external disturbances, and unmodeled dynamics;

[0013] The dynamic equation of hydraulic cylinder load pressure is:

[0014]

[0015] Where: V t Indicates the total effective volume of the two chambers of the hydraulic cylinder, β e is the effective oil elastic modulus, C t is the hydraulic cylinder leakage coefficient, Q L =(Q1+Q2) / 2 is the load flow, Q1 is the oil supply flow of the hydraulic cylinder oil inlet chamber, Q2 is the oil return flow of the hydraulic cylinder oil return chamber, and q(t) is the modeling error and unmodeled dynamics;

[0016] Q L is the servo valve spool displacement x v Function:

[0017]

[0018] Where: is the gain coefficient of the flow servo valve, C d is the flow coefficient of the servo valve, w is the area gradient of the servo valve, ρ is the density of the hydraulic oil, P s is the oil supply pressure;

[0019] sign(x v )for:

[0020]

[0021] Assume that the servo valve spool displacement is proportional to the control input u, that is, x v =k i u, where k i >0 is the proportionality coefficient, and u is the control input voltage; therefore, equation (3) can be transformed into:

[0022]

[0023] Where: k t =k q k i represents the total flow gain;

[0024] Defining state variables Then the whole system can be written in the following state space form:

[0025]

[0026] In the formula: β1=B / m, β2=4β e A 2 / mV t , β3=4β e C t / V t , d2(t)=4β e Aq(t) / mV t It is hoped that the output state of the system is constrained in Ω, Ω = {x i :|x i |≤c i ,i=1,2,3},c i >0 is a constant;

[0027] Assumption 1: The derivatives of d1(x,t) and d2(t) are bounded, that is

[0028]

[0029] Where: δ, ζ are known normal constants;

[0030] Assumption 2: Expected instruction x 1d (t) and its time i-th reciprocal Satisfy x 1d (t)≤υ0≤c1-L1, υ i >0 is a constant, L1>0 is a design parameter.

[0031] Furthermore, in the above-mentioned electro-hydraulic servo system preset performance output feedback control method based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S2 are:

[0032] S2.1: Construct state observer and disturbance observer;

[0033] S2.2: Design controller;

[0034] S2.3: Verify system stability.

[0035] Furthermore, in the above-mentioned preset performance output feedback control method of the electro-hydraulic servo system based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S2.1 are: in order to compensate for the uncertainty of the system in the controller, an extended state observer is designed, and the extended state x e =d2(t), based on formula (6), the extended state observer (ESO) is designed as follows:

[0036]

[0037] Where: ω>0 is the observer parameter, is the estimated value of , represents the estimation error;

[0038] definition The error dynamics can be obtained as follows:

[0039]

[0040] Where: C1=[0,1,0,0] T , C2=[0,0,1,0] T , C3=[0,0,0,1] T , h(t) is the derivative of d2(t);

[0041] Since A is a Hurwitz matrix, there exists a positive definite matrix P such that A T P+PA=-2I;

[0042] To estimate the system mismatched disturbance, the nonlinear disturbance observer is designed as follows:

[0043] First, define a new transition state χ

[0044] χ=d1-μ1x2 (10)

[0045] Where: μ1>0 is the observer parameter;

[0046] From formula (6), we can get:

[0047]

[0048] According to the above formula, the estimate of χ can be designed as follows:

[0049]

[0050] Then, we can get an estimate of d1:

[0051]

[0052] From (10) and (13), we can get:

[0053]

[0054] The estimated error dynamics of χ is:

[0055]

[0056] Furthermore, in the above-mentioned electro-hydraulic servo system preset performance output feedback control method based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S2.2 are: define the tracking error e(t) = x1-x 1d , in order to achieve the preset control performance, the tracking error e(t) is required to strictly satisfy the following inequality:

[0057]

[0058] Where: g(t) is a positive strictly decreasing smooth preset performance function, and its equation is as follows:

[0059]

[0060] Where: g0, g ∞ , k is a positive constant; g0 represents the limit of the maximum overshoot, k represents the convergence speed, and the steady-state tracking error e(t) is affected by g ∞ constraint.

[0061] Furthermore, in the above-mentioned preset performance output feedback control method of the electro-hydraulic servo system based on disturbance compensation and full-state constraints, by selecting appropriate preset performance function parameters, the transient and steady-state performance of the system can be improved;

[0062] Step 1: Define the errors z2=x2-α1, z3=x3-α2, where α1 and α2 are the virtual control laws of x2 and x3 respectively; define the obstacle Lyapunov function combined with the preset performance function as follows:

[0063]

[0064] Where: z1 = e(t) / g(t);

[0065] By taking the derivative of formula (18), we can get:

[0066]

[0067] The virtual control law α1 is designed as:

[0068]

[0069] Where: k1>0 is the controller gain;

[0070] At this time, the time derivative of function V1 is:

[0071]

[0072] According to Young's inequality, we can get:

[0073]

[0074] Substituting (22) into (21) yields:

[0075]

[0076] Step 2: Define the following barrier Lyapunov function:

[0077]

[0078] Where: L2>0 is the design parameter;

[0079] The time derivative of function V2 is:

[0080]

[0081] α2 is the virtual control law of the second step, which is designed as follows:

[0082]

[0083] Where: k2>0 is the controller gain. is the computable part, is the incalculable part,

[0084] Substituting (26) into (25), we get:

[0085]

[0086] Step 3: Design the actual control input u to ensure that z3 does not violate the preset range (-L3, L3). To this end, define the following obstacle Lyapunov function:

[0087]

[0088] Where: L3>0 is the design parameter;

[0089] The time derivative of function V3 is:

[0090]

[0091] The control law u is designed as follows:

[0092]

[0093] Where: k3>0 is the controller gain,

[0094]

[0095] Where: and They are of computable and incomputable quantities;

[0096]

[0097] According to Young's inequality, we can get:

[0098]

[0099] Substituting (34) into (33) we obtain;

[0100]

[0101] Furthermore, in the above-mentioned electro-hydraulic servo system preset performance output feedback control method based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S2.3 are: In order to facilitate subsequent analysis, a set of scalars is expressed as:

[0102]

[0103] γ2=μ1-1 (36)

[0105] If the following conditions are met:

[0106] (1) Appropriate parameters can be selected to satisfy the following matrix:

[0107]

[0108] (2) The initial value z(0) of the system can satisfy the following conditions:

[0109]

[0110] Then the controller (31) has the following conclusion:

[0111] Performance Theorem 1: All signals in a closed-loop control system are bounded, and the system tracking error and state can be effectively constrained; the positive definite Lyapunov function is defined as follows:

[0112]

[0113] Then it satisfies:

[0114]

[0115] Where: λ min (·) and λ max (·) are the minimum and maximum eigenvalues ​​of ·,

[0116] Proof of Performance Theorem 1: Derivative (39) and substitute (9) and (15) into it to obtain:

[0117]

[0118] Because A T P+PA=-2I, we can get:

[0119]

[0120] According to Young's inequality:

[0121]

[0122]

[0123]

[0124]

[0125]

[0126]

[0127] Substituting (43) into (42) yields:

[0128]

[0129] When z j <L j When but:

[0130]

[0131] Integrating (45) yields (40), so the error z i , and is bounded, e1 is also bounded, and further we know that and is bounded; since x1=e(t)+x 1d(t), z1=e(t) / ρ(t), |z1|<1, based on assumption 2, we can get |x1|≤c1. And because α1 is z1 and function. x1, z1 and is bounded, so α1 is bounded; by From |z2|<L2, we can see that |x2|≤c2, and α2 is bounded; similarly, |x3| and u are bounded, so all signals in the closed-loop system are bounded, and the system tracking error can be constrained within the preset performance function boundary. In addition, the state of the system is also constrained; therefore, the controller is convergent and the system is stable.

[0132] Furthermore, in the above-mentioned preset performance output feedback control method of the electro-hydraulic servo system based on disturbance compensation and full-state constraints, the specific steps of the above-mentioned S3 are: adjusting the parameters k1, k2, k3, ω, μ1, L2, L3, g0, g ∞ , k makes the system meet the control performance indicators.

[0133] Compared with the prior art, the present invention has the following beneficial effects:

[0134] The present invention establishes a valve-controlled double-rod hydraulic cylinder position servo system model based on the characteristics of the valve-controlled double-rod hydraulic cylinder position servo system; the electro-hydraulic servo system preset performance output feedback controller based on the obstacle Lyapunov function designed by the present invention estimates the system interference and unknown state and uses them for controller design, which can effectively improve the practicability of the electro-hydraulic servo system and greatly reduce the feedback gain of the system; in addition, considering the system tracking error and state constraint problems, the tracking error and state of the system are constrained by designing a preset performance function and an obstacle Lyapunov function, ensuring that the position output of the double-rod hydraulic cylinder servo system can accurately track the expected position instruction; the present invention simplifies the controller design and is more conducive to application in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0136] Figure 1 This is a schematic diagram of preset performance control of the present invention;

[0137] Figure 2 It is a schematic diagram of a double-rod hydraulic cylinder system of the present invention;

[0138] Figure 3 The invention expects instruction x1d , schematic diagram of output state x1 and control input u;

[0139] Figure 4 Schematic diagram of tracking errors and preset performance function boundaries of two controllers of the present invention;

[0140] Figure 5 Schematic diagram of system states x1, x2 and x3 of the present invention; DETAILED DESCRIPTION

[0141] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0142] The present invention provides a technical solution:

[0143] A method for output feedback control of a preset performance of an electro-hydraulic servo system based on disturbance compensation and full-state constraints, characterized in that it comprises the following steps:

[0144] S1: Establish a double-rod hydraulic cylinder servo system model; according to Newton's second law, the dynamic model equation of the double-rod hydraulic cylinder inertial load is:

[0145]

[0146] Where: y is the load displacement, m is the inertial load, P L =P1-P2 is the load driving pressure, P1 and P2 are the pressures in the two chambers of the hydraulic cylinder, A is the effective working area of ​​the piston rod, and B represents the viscous friction coefficient. represents other unmodeled disturbances, such as nonlinear friction, external disturbances, and unmodeled dynamics;

[0147] The dynamic equation of hydraulic cylinder load pressure is:

[0148]

[0149] Where: V t Indicates the total effective volume of the two chambers of the hydraulic cylinder, β e is the effective oil elastic modulus, C t is the hydraulic cylinder leakage coefficient, Q L =(Q1+Q2) / 2 is the load flow, Q1 is the oil supply flow of the hydraulic cylinder oil inlet chamber, Q2 is the oil return flow of the hydraulic cylinder oil return chamber, and q(t) is the modeling error and unmodeled dynamics;

[0150] QL is the displacement x of the servo valve corev Function:

[0151]

[0152] Where: is the gain coefficient of the flow servo valve, C d is the flow coefficient of the servo valve, w is the area gradient of the servo valve, ρ is the density of the hydraulic oil, P s is the oil supply pressure;

[0153] sign(x v )for:

[0154]

[0155] Assume that the servo valve spool displacement is proportional to the control input u, that is, x v =k i u, where k i >0 is the proportionality coefficient, and u is the control input voltage; therefore, equation (3) can be transformed into:

[0156]

[0157] Where: k t =k q k i represents the total flow gain;

[0158] Defining state variables Then the whole system can be written in the following state space form:

[0159]

[0160] In the formula: β1=B / m, β2=4β e A 2 / mV t , β3=4β e C t / V t , d2(t)=4β e Aq(t) / mV t It is hoped that the output state of the system is constrained in Ω, Ω = {x i :|x i |≤c i ,i=1,2,3},c i >0 is a constant;

[0161] Assumption 1: The derivatives of d1(x,t) and d2(t) are bounded, that is

[0162]

[0163] Where: δ, ζ are known normal constants;

[0164] Assumption 2: Expected instruction x 1d (t) and its time i-th reciprocal Satisfy x 1d (t)≤υ0≤c1-L1, υ i >0 is a constant, L1>0 is a design parameter.

[0165] S2: Design a preset performance controller for an electro-hydraulic servo system based on model uncertainty compensation and full-state constraints;

[0166] S2.1: Construct state observer and disturbance observer; In order to compensate for the uncertainty of the system in the controller, an extended state observer is designed. e =d2(t), based on formula (6), the extended state observer (ESO) is designed as follows:

[0167]

[0168] Where: ω>0 is the observer parameter, is the estimated value of , represents the estimation error;

[0169] definition The error dynamics can be obtained as follows:

[0170]

[0171] Where: C1=[0,1,0,0] T , C2=[0,0,1,0] T , C3=[0,0,0,1] T , h(t) is the derivative of d2(t);

[0172] Since A is a Hurwitz matrix, there exists a positive definite matrix P such that A T P+PA=-2I;

[0173] To estimate the system mismatched disturbance, the nonlinear disturbance observer is designed as follows:

[0174] First, define a new transition state χ

[0175] χ=d1-μ1x2 (10)

[0176] Where: μ1>0 is the observer parameter;

[0177] From formula (6), we can get:

[0178]

[0179] According to the above formula, the estimate of χ can be designed as follows:

[0180]

[0181] Then, we can get an estimate of d1:

[0182]

[0183] From (10) and (13), we can get:

[0184]

[0185] The estimated error dynamics of χ is:

[0186]

[0187] S2.2: Design controller; define tracking error e(t) = x1-x 1d , in order to achieve the preset control performance, the tracking error e(t) is required to strictly satisfy the following inequality:

[0188]

[0189] Where: g(t) is a positive strictly decreasing smooth preset performance function, and its equation is as follows:

[0190]

[0191] Where: g0, g ∞ , k is a positive constant; g0 represents the limit of the maximum overshoot, k represents the convergence speed, and the steady-state tracking error e(t) is affected by g ∞ constraint.

[0192] By selecting appropriate preset performance function parameters, the transient and steady-state performance of the system can be improved;

[0193] Step 1: Define the errors z2=x2-α1, z3=x3-α2, where α1 and α2 are the virtual control laws of x2 and x3 respectively; define the obstacle Lyapunov function combined with the preset performance function as follows:

[0194]

[0195] Where: z1 = e(t) / g(t);

[0196] By taking the derivative of formula (18), we can get:

[0197]

[0198] The virtual control law α1 is designed as:

[0199]

[0200] Where: k1>0 is the controller gain;

[0201] At this time, the time derivative of function V1 is:

[0202]

[0203] According to Young's inequality, we can get:

[0204]

[0205] Substituting (22) into (21) yields:

[0206]

[0207] Step 2: Define the following barrier Lyapunov function:

[0208]

[0209] Where: L2>0 is the design parameter;

[0210] The time derivative of function V2 is:

[0211]

[0212] α2 is the virtual control law of the second step, which is designed as follows:

[0213]

[0214] Where: k2>0 is the controller gain. is the computable part, is the incalculable part,

[0215] Substituting (26) into (25), we get:

[0216]

[0217] Step 3: Design the actual control input u to ensure that z3 does not violate the preset range (-L3, L3). To this end, define the following obstacle Lyapunov function:

[0218]

[0219] Where: L3>0 is the design parameter;

[0220] The time derivative of function V3 is:

[0221]

[0222] The control law u is designed as follows:

[0223]

[0224] Where: k3>0 is the controller gain,

[0225]

[0226] Where: and They are of computable and incomputable quantities;

[0227]

[0228] According to Young's inequality, we can get:

[0229]

[0230] Substituting (34) into (33) we obtain;

[0231]

[0232] S2.3: Verify system stability. To facilitate subsequent analysis, a set of scalars is expressed as:

[0233]

[0234] γ2=μ1-1 (36)

[0236] If the following conditions are met:

[0237] (1) Appropriate parameters can be selected to satisfy the following matrix:

[0238]

[0239] (2) The initial value z(0) of the system can satisfy the following conditions:

[0240]

[0241] Then the controller (31) has the following conclusion:

[0242] Performance Theorem 1: All signals in a closed-loop control system are bounded, and the system tracking error and state can be effectively constrained; the positive definite Lyapunov function is defined as follows:

[0243]

[0244] Then it satisfies:

[0245]

[0246] Where: λ min (·) and λ max (·) are the minimum and maximum eigenvalues ​​of ·,

[0247] Proof of Performance Theorem 1: Derivative (39) and substitute (9) and (15) into it to obtain:

[0248]

[0249] Because A T P+PA=-2I, we can get:

[0250]

[0251] According to Young's inequality, we can get:

[0252]

[0253]

[0254]

[0255]

[0256]

[0257]

[0258] Substituting (43) into (42) yields:

[0259]

[0260] When z j <L j When but:

[0261]

[0262] Integrating (45) yields (40), so the error z i , and is bounded, e1 is also bounded, and further we know that and is bounded; since x1=e(t)+x 1d(t), z1=e(t) / ρ(t), |z1|<1, based on assumption 2, we can get |x1|≤c1. And because α1 is z1 and function. x1, z1 and is bounded, so α1 is bounded; by From |z2|<L2, we can see that |x2|≤c2, and α2 is bounded; similarly, |x3| and u are bounded, so all signals in the closed-loop system are bounded, and the system tracking error can be constrained within the preset performance function boundary. In addition, the state of the system is also constrained; therefore, the controller is convergent and the system is stable.

[0263] S3: Adjust the parameters k1, k2, k3, ω, μ1, L2, L3, g0, g based on the control law u ∞ , k makes the system meet the control performance indicators.

[0264] This paper designs a controller and takes the following parameters to experiment on the system: m = 30 kg, A = 2 × 10 -4 m 2 , b=2000N·s / m, β e =700Mpa, V 01 =1×10 -3 m 3 ,V 02 =1×10 -3 m 3 ,C t =9×10 -12 m 5 / Ns, P s =10Mpa,P r =0Mpa. In order to verify the performance of the designed controller, the following two controllers are compared:

[0265] 1) The preset performance output feedback controller (PPOFC) of the electro-hydraulic servo system based on the barrier Lyapunov function proposed in this chapter has the following controller parameters: k1=1300, k2=800, k3=220, μ1=200, ω=350, L2=30, L3=500, g0=0.2, g ∞ =0.06, k=2.

[0266] 2) VFPI: Speed ​​feedforward proportional integral controller, the parameters obtained through self-tuning are: k p =4200,k i =1206, k v =6.

[0267] The system command is x 1d=10arctan(sin(2πt)) / 0.7815, the effect of the control law can be seen from the attached figure; combined with the attached figure, it can be seen that compared with the traditional VFPI controller, the controller designed by the present invention can achieve good output feedback control accuracy, can effectively constrain the system tracking error and state, and the research results show that under the influence of uncertainty, the method proposed in this paper can meet the performance indicators.

[0268] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0269] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A preset performance output feedback control method for an electro-hydraulic servo system based on disturbance compensation and full-state constraints, characterized in that: The following steps are involved: S1: Establish a double-rod hydraulic cylinder servo system model; S2: Design a preset performance controller for an electro-hydraulic servo system based on model uncertainty compensation and full-state constraints; S3: Adjustment of parameters based on control law u; The specific steps of S1 above are: According to Newton's second law, the dynamic model equation of the inertial load of the double-rod hydraulic cylinder is: Where: y is the load displacement, m is the inertial load, P L =P1-P2 is the load driving pressure, P1 and P2 are the pressures in the two chambers of the hydraulic cylinder, A is the effective working area of ​​the piston rod, and B represents the viscous friction coefficient. represents other unmodeled disturbances, including nonlinear friction, external disturbances, and unmodeled dynamics; The dynamic equation of hydraulic cylinder load pressure is: Where: V t Indicates the total effective volume of the two chambers of the hydraulic cylinder, β e is the effective oil elastic modulus, C t is the hydraulic cylinder leakage coefficient, Q L =(Q1+Q2) / 2 is the load flow, Q1 is the oil supply flow of the hydraulic cylinder oil inlet chamber, Q2 is the oil return flow of the hydraulic cylinder oil return chamber, and q(t) is the modeling error and unmodeled dynamics; Q L is the servo valve spool displacement x v Function: Where: is the gain coefficient of the flow servo valve, C d is the flow coefficient of the servo valve, w is the area gradient of the servo valve, ρ is the density of the hydraulic oil, P s is the oil supply pressure; sign(x v )for: Assume that the servo valve spool displacement is proportional to the control input u, that is, x v =k i u, where k i >0 is the proportionality coefficient, and u is the control input voltage; therefore, equation (3) is transformed into: Where: k t =k q k i represents the total flow gain; Defining state variables Then the whole system is written in the following state space form: In the formula: β1=B / m, β2=4β e A 2 / mV t ,β3=4β e C t / V t , d2(t)=4β e Aq(t) / mV t ; It is hoped that the output state of the system is constrained in Ω, Ω = {x i :|x i |≤c i ,i=1,2,3},c i >0 is a constant; Assumption 1: The derivatives of d1(x,t) and d2(t) are bounded, that is Where: δ, ζ are known normal constants; Assumption 2: Expected instruction x 1d (t) and its time i-th reciprocal i=1, 2, 3 satisfy x 1d (t)≤υ0≤c1-L1, υ i >0 is a constant, L1>0 is a design parameter; The specific steps of S2.2 are as follows: define the tracking error e(t) = x1-x 1d , in order to achieve the preset control performance, the tracking error e(t) is required to strictly satisfy the following inequality: Where: g(t) is a positive strictly decreasing smooth preset performance function, and its equation is as follows: Where: g0, g ∞ , k is a positive constant; g0 represents the limit of the maximum overshoot, k represents the convergence speed, and the steady-state tracking error e(t) is affected by g ∞ constraint; By selecting appropriate preset performance function parameters, the transient and steady-state performance of the system can be improved; Step 1: Define the errors z2=x2-α1, z3=x3-α2, where α1 and α2 are the virtual control laws of x2 and x3 respectively; define the obstacle Lyapunov function combined with the preset performance function as follows: Where: z1 = e(t) / g(t); By taking the derivative of formula (18), we can get: The virtual control law α1 is designed as: Where: k1>0 is the controller gain; At this time, the time derivative of function V1 is: According to Young's inequality: Substituting formula (22) into formula (21) yields: Step 2: Define the following barrier Lyapunov function: Where: L2>0 is the design parameter; The time derivative of function V2 is: α2 is the virtual control law of the second step, which is designed as follows: Where: k2>0 is the controller gain; is the computable part, is the incalculable part, Substituting formula (26) into formula (25) yields: Step 3: Design the actual control input u to ensure that z3 does not violate the preset range (-L3, L3); for this purpose, define the following obstacle Lyapunov function: Where: L3>0 is the design parameter; The time derivative of function V3 is: The control law u is designed as follows: Where: k3>0 is the controller gain, Where: and They are of computable and incomputable quantities; According to Young's inequality: Substituting equation (34) into equation (33), we can obtain: The specific steps of S3 are as follows: adjusting the parameters k1, k2, k3, ω, μ1, L2, L3, g0, g ∞ , k makes the system meet the control performance indicators.

2. The method for controlling the preset performance output feedback of an electro-hydraulic servo system based on disturbance compensation and full-state constraints according to claim 1, characterized in that: The specific steps of S2 above are: S2.1: Construct state observer and disturbance observer; S2.2: Design controller; S2.3: Verify system stability.

3. The method for controlling the preset performance output feedback of an electro-hydraulic servo system based on disturbance compensation and full-state constraints according to claim 2, characterized in that: The specific steps of S2.1 above are: In order to compensate for the uncertainty of the system in the controller, an extended state observer is designed. The extended state x e =d2(t), based on formula (6), the extended state observer (ESO) is designed as follows: Where: ω>0 is the observer parameter, for The estimated value of represents the estimation error; definition The error dynamics can be obtained as follows: Where: C1=[0,1,0,0] T , C2=[0,0,1,0] T , C3=[0,0,0,1] T , h(t) is the derivative of d2(t); Since A is a Hurwitz matrix, there exists a positive definite matrix P such that A T P+PA=-2I; To estimate the system mismatched disturbance, the nonlinear disturbance observer is designed as follows: First, define a new transition state χ χ=d1-μ1x2 (10) Where: μ1>0 is the observer parameter; From formula (6), we can get: According to the above formula, the estimate of χ can be designed as follows: Then, we can get an estimate of d1: From formula (10) and formula (13), we can get: The estimated error dynamics of χ is:

4. The method for controlling the preset performance output feedback of an electro-hydraulic servo system based on disturbance compensation and full-state constraints according to claim 2, characterized in that: The specific steps of S2.3 above are: To facilitate subsequent analysis, a set of scalars is expressed as: If the following conditions are met: (1) Appropriate parameters can be selected to satisfy the following matrix: (2) The initial value z(0) of the system satisfies the following conditions: Then the controller (31) has the following conclusion: Performance Theorem 1: All signals in a closed-loop control system are bounded, and the system tracking error and state can be effectively constrained; the positive definite Lyapunov function is defined as follows: Then it satisfies: Where: λ min (●) and λ max (●) are the minimum and maximum eigenvalues ​​of ●, Proof of Performance Theorem 1: Derivative (39) and substitute (9) and (15) into the equation to obtain: Because A T P+PA=-2I, we can get: According to Young's inequality: Substituting formula (43) into formula (42) yields: When z j <L j When but: Integrating equation (45) yields equation (40), so the error z i , and is bounded, e1 is also bounded, and further we know that and is bounded; since x1=e(t)+x 1d (t), z1=e(t) / ρ(t), |z1|<1, based on assumption 2, we can get |x1|≤c1; and because α1 is z1 and function; x1, z1 and is bounded, so α1 is bounded; by From |z2|<L2, we can see that |x2|≤c2, and α2 is bounded; similarly, |x3| and u are bounded, so all signals in the closed-loop system are bounded, and the system tracking error can be constrained within the preset performance function boundary. In addition, the state of the system is also constrained; therefore, the controller is convergent and the system is stable.

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