Method for constructing high-frequency response characteristic model of electrohydraulic active suspension

Abstract

The present invention relates to the field of automotive control technology, and in particular to a method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension, comprising: constructing a refined model of the hydraulic-electric active suspension based on the nonlinear factors of the hydraulic-electric active suspension; decoupling the established refined model, conducting simulation experiments on the hydraulic-electric active suspension, and obtaining basic vectors used to describe the active suspension from the theoretical basic vectors obtained by decoupling; applying high-frequency excitation to the hydraulic-electric active suspension and determining a preliminary high-frequency response model of the hydraulic-electric active suspension; and fitting and optimizing the preliminary high-frequency response model using the obtained basic vectors to obtain a high-frequency response characteristic model of the hydraulic-electric active suspension. The present invention reveals the intrinsic relationship between system parameters and high-frequency response characteristics by combining theoretical analysis with experimental verification, thereby constructing a model that is both accurate and efficient.

Description

Technical Field

[0001] The present invention belongs to the field of automobile control technology, and in particular relates to a method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension. Background Art

[0002] During vehicle driving, uneven road conditions can cause the vehicle to vibrate and change its posture, affecting the vertical force on the tires and altering the vehicle's ride comfort and handling stability. The electrohydraulic active suspension effectively controls vehicle vibration and posture, improving ride comfort and handling stability by controlling the rotation of the hydraulic pump to adjust the pressure difference on both sides of the piston to output control force in real time. The electrohydraulic active suspension uses electrical energy, kinetic energy, and liquid pressure energy as the energy transfer link. The electrohydraulic active suspension's motor converts the vehicle's electrical energy into kinetic energy, which is then linked to the hydraulic pump to convert the kinetic energy into liquid pressure energy. This force is then transferred to the sprung and unsprung masses via hydraulic cylinders, thereby achieving active control of the vehicle's vertical motion.

[0003] Current active suspension modeling methods focus on electromechanical active suspension. The Chinese patent application, CN115828419A, published on March 21, 2023, and titled "A Method for Modeling Electromechanical Active Suspension," establishes a complete mathematical model for electromechanical active suspension in the fields of kinematics and dynamics. Modeling for hydro-electric active suspensions is primarily performed using software based on characteristic solutions and finite element methods. The existing technology suffers from the following deficiencies:

[0004] (1) High model solution complexity: The electrohydraulic active suspension system involves multiple nonlinear links, such as friction in the hydraulic cylinder, compressibility of the oil, dynamic characteristics of the pipeline fluid, and electromagnetic and mechanical characteristics of the motor. This makes accurate model calculation complex and difficult to solve in real time, limiting its widespread application in vehicle dynamic control.

[0005] (2) Unclear relationship between system parameters and high-frequency response characteristics: High-frequency vibration is an important part of vehicle driving and has a significant impact on ride comfort and vehicle stability. However, existing models often fail to directly reveal the clear relationship between model parameters (such as the structure of the hydraulic cylinder, the characteristics of the damping orifice, the characteristics of the pipeline fluid, the response characteristics of the motor, the characteristics of the external excitation source, etc.) and the high-frequency response characteristics of the suspension, resulting in a lack of effective basis for design optimization, fault diagnosis, and performance evaluation. Summary of the Invention

[0006] In view of this, the present invention aims to provide a method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension to meet the demand for real-time solution of the high-frequency response characteristics of the hydraulic-electric active suspension, reveal the influence mechanism between system parameters and the high-frequency response characteristics of the active suspension, and ensure the accuracy and rapid solution of the model.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0008] A method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension includes:

[0009] S1: Based on the nonlinear factors of the hydraulic active suspension, a refined model of the hydraulic active suspension is constructed;

[0010] S2: Decoupling the refined model established in step S1, and conducting a simulation experiment on the electrohydraulic active suspension, to obtain basic vectors used to describe the active suspension from the theoretical basic vectors obtained by decoupling;

[0011] S3: Apply high-frequency excitation to the electrohydraulic active suspension and determine the preliminary high-frequency response model of the electrohydraulic active suspension;

[0012] S4: Using the basic vectors obtained in step S2, the preliminary high-frequency response model of step S3 is fitted and optimized to obtain a high-frequency response characteristic model of the electro-hydraulic active suspension.

[0013] Furthermore, the nonlinear factors in step S1 include friction factors of the hydraulic cylinder, oil leakage factors, oil compression factors, hydraulic pipeline factors, hydraulic component characteristic factors, and motor factors of the active suspension; wherein:

[0014] The friction factor is expressed as follows:

[0015] F fiction =μ·(P·A)·sign(v)+b·v;

[0016] Among them, F fiction represents the friction force of the hydraulic cylinder, μ represents the friction coefficient, P represents the working pressure, A represents the effective area of ​​the piston in the hydraulic cylinder, v represents the movement speed of the piston in the hydraulic cylinder, and b represents the viscous friction coefficient of the lubricating fluid in the hydraulic cylinder;

[0017] The oil leakage factor is expressed by the following formula:

[0018] Q=K·ΔP·e αT ;

[0019] Where K represents the total correction factor and ΔP represents the working pressure difference;

[0020] The oil compressibility factor is expressed by the following formula:

[0021] ;

[0022] Among them, K eff represents the effective elastic modulus of the gas-containing oil; B represents damping, ρ represents the fluid density of the oil, c represents the pressure wave velocity, L represents the length of the pipeline through which the oil flows, ω represents the excitation frequency, and ΔP res represents the peak value of pressure fluctuation caused by oil compressibility, φ represents the phase corresponding to the excitation frequency ω, represents the equivalent time delay;

[0023] The hydraulic pipeline factor is expressed by the following formula

[0024] ;

[0025] Among them, P i-loss It represents the pressure loss along the i-th section of pipeline, L i represents the length of the i-th pipeline, v i represents the dynamic viscosity in the i-th section of the pipeline, f i It is obtained from the following formula:

[0026] ;

[0027] Among them, R ei represents the Reynolds number of the i-th pipeline, λ i represents the wall roughness of the i-th section of pipeline;

[0028] The hydraulic component characteristic factors include the small hole fluid characteristic factors and the throttle valve fluid characteristic factors;

[0029] Motor factors include the relationship between the voltage, current and speed of the active suspension motor, the torque conditions and the mechanical movement conditions.

[0030] Furthermore, factors of the small hole fluid characteristics include the small hole flow characteristics and the local pressure loss of the small hole;

[0031] The orifice flow characteristics are expressed by the following formula:

[0032] ;

[0033] Among them, Q s Indicates the flow rate of the small hole, C q represents the flow coefficient, A represents the orifice cross-sectional area,

[0034] The local pressure loss of the small hole is obtained by the following formula:

[0035] ;

[0036] in, Indicates the local pressure loss of the small hole.

[0037] Furthermore, the throttle valve fluid characteristic factors include the flow characteristics of the throttle valve and the local pressure loss of the throttle valve;

[0038] The flow characteristics of the throttle valve are expressed by the following formula:

[0039] ;

[0040] Among them, Q j represents the flow rate of the throttle valve, A(x) represents the orifice cross-sectional area;

[0041] The local pressure loss of the throttle valve is expressed by the following formula:

[0042] .

[0043] Furthermore, in step S1, the process of constructing a refined model of the electro-hydraulic active suspension includes:

[0044] High-order differential equations are used to describe the flow and pressure of the hydraulic cylinder, as well as the dynamic changes of the current and speed of the motor to obtain a refined model, and the model parameters of the refined model are estimated using a system identification algorithm.

[0045] Furthermore, step S2 includes:

[0046] S21: Determine the mathematical relationship between the motion parameters of the vehicle as it traverses the road surface and the dynamic response of the electrohydraulic active suspension based on the key parameters of the electrohydraulic active suspension and the load input;

[0047] S22: Decoupling the refined model using a differential geometry decoupling method for the mathematical relationship obtained in step S1 to obtain theoretical basic vectors for describing the active suspension;

[0048] S23: Based on the theoretical basic vector obtained in step S22, a sensitivity test analysis is performed on the vehicle, and multiple parameters in the theoretical basic vector that have the greatest impact on the high-frequency response characteristics of the suspension are combined into a basic vector.

[0049] Furthermore, step S21 includes:

[0050] Based on the principles of fluid mechanics, electricity, and mechanical dynamics, a first mathematical relationship between the load input of the electrohydraulic active suspension and the dynamic response of the electrohydraulic active suspension is obtained;

[0051] Based on the principles of vehicle dynamics and tire dynamics, a second mathematical relationship between the motion parameters and the load input of the hydro-electric active suspension is obtained;

[0052] The mathematical relationship between the motion parameter and the dynamic response is obtained by combining the first mathematical relationship obtained in step S21 and the second mathematical relationship obtained in step S22.

[0053] Furthermore, step S3 includes:

[0054] Perform time and frequency domain analysis on a hydro-electric active suspension subjected to high-frequency excitation to obtain high-frequency characteristic parameters describing amplitude attenuation and phase lag in the high-frequency band.

[0055] Based on the high-frequency characteristic parameters, the excitation frequency of the high-frequency excitation and the system parameters of the electrohydraulic active suspension, a preliminary high-frequency response model is fitted using the statistical learning method.

[0056] Furthermore, in step S4: the basic vectors are used in combination with an optimization algorithm to perform fitting optimization on the preliminary high-frequency response model to obtain a high-frequency response characteristic model.

[0057] Furthermore, step S4 further includes simplifying the preliminary high-frequency response model using a model order reduction technique to reduce the complexity of the preliminary high-frequency response model.

[0058] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0059] (1) The method for constructing the high-frequency response characteristic model of the hydraulic-electric active suspension created by the present invention extracts the key parameters of the hydraulic-electric active suspension model by combining theoretical derivation with experimental verification, and abstracts the basic vectors that affect the high-frequency excitation response characteristics of the hydraulic-electric active suspension model, thereby providing a solid foundation for subsequent model construction and performance analysis.

[0060] (2) The present invention creates a method for constructing a high-frequency response characteristic model of a hydro-electric active suspension, conducts in-depth research on the dynamic behavior of the suspension under high-frequency excitation, and abstracts key characteristics such as high-frequency amplitude attenuation and phase lag, providing an important basis for optimizing suspension performance and developing intelligent control strategies.

[0061] (3) The present invention creates a method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension, which utilizes basic vectors and abstracted high-frequency response characteristics to construct a high-frequency response characteristic model with both solution speed and model accuracy:

[0062] (4) The method for constructing the high-frequency response characteristic model of the electric-hydraulic active suspension created by the present invention innovatively combines model order reduction technology, optimization algorithm, etc., and uses the abstracted basic vectors and high-frequency response characteristics to construct a high-frequency response characteristic model of the electric-hydraulic active suspension that has both efficient solution speed and guaranteed model accuracy, thus solving the problem in the prior art of difficulty in balancing solution speed and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0064] Figure 1 A schematic flow chart of a method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to an embodiment of the present invention;

[0065] Figure 2 This is a flowchart of step S1 according to an embodiment of the present invention;

[0066] Figure 3 This is a flowchart of step S2 according to an embodiment of the present invention;

[0067] Figure 4 This is a flowchart of step S3 according to an embodiment of the present invention;

[0068] Figure 5 This is a flowchart of step S4 according to an embodiment of the present invention;

[0069] Figure 6 A schematic diagram of a hydraulic-electric active suspension according to an embodiment of the present invention;

[0070] Figure 7 This is a schematic diagram of an AMESIM simulation of a hydraulic cylinder according to an embodiment of the present invention;

[0071] Figure 8 A graph showing the force characteristics of the electric-hydraulic active suspension according to an embodiment of the present invention;

[0072] Figure 9 A frequency domain response Bode diagram of the amplitude of the electrohydraulic active suspension according to an embodiment of the present invention;

[0073] Figure 10 The frequency domain response Bode diagram of the phase of the electrohydraulic active suspension described in the embodiment of the present invention is created. DETAILED DESCRIPTION

[0074] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0075] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0076] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0077] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0078] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0079] like Figures 1 to 7 As shown, the method for constructing the high-frequency response characteristic model of the electric-hydraulic active suspension according to the embodiment of the present invention includes:

[0080] S1: Based on the nonlinear factors of the hydraulic active suspension, a refined model of the hydraulic active suspension is constructed.

[0081] In some embodiments, the nonlinear factors in step S1 include friction factors of the hydraulic cylinder, oil leakage factors, oil compression factors, hydraulic pipeline factors, hydraulic component characteristics factors, and motor factors.

[0082] A detailed analysis of the friction force of the hydraulic cylinder is conducted, taking into account its variation with pressure and speed. The friction factor is expressed by the following formula:

[0083] F fiction =μ·(P·A)·sign(v)+b·v;

[0084] Among them, F fictionrepresents the friction force of the hydraulic cylinder, μ represents the friction coefficient, P represents the hydraulic cylinder's operating pressure (Pa), A represents the effective area of ​​the piston in the hydraulic cylinder (m²), v represents the piston's velocity in the hydraulic cylinder (m / s), and b represents the viscous friction coefficient of the lubricant in the hydraulic cylinder (N·s / m). The friction coefficient μ is related to the seal material and surface roughness, while the viscous friction coefficient b is related to the lubricant's viscosity and clearance.

[0085] In-depth study of hydraulic cylinder leakage, including the relationship between leakage volume, pressure difference, and oil temperature, that is, the oil leakage factor is expressed by the following formula:

[0086] Q=K·ΔP·e αT ;

[0087] Where Q is the leakage flow, K is the total correction factor, ΔP is the working pressure difference on both sides of the piston (Pa), α is the temperature correction factor, and T is the temperature;

[0088] Analyze the compressibility of the oil, especially the impact of the oil compressibility on the dynamic response of the system under high-frequency excitation. That is, the oil compressibility factor is expressed by the following formula:

[0089] ;

[0090] In the above formula, is the mechanical dynamics term, where K eff represents the effective elastic modulus of the gas-laden oil; B represents the damping term caused by the compressibility of the oil; is the pressure fluctuation caused by the flow excitation propagating through the pipeline, ρ represents the fluid density of the oil, L represents the length of the pipeline through which the oil flows, ω represents the excitation frequency of the external input, c represents the oil pressure wave velocity, and the pressure wave velocity ; is the standing wave resonance term, ΔP res represents the peak value of pressure fluctuation caused by oil compressibility; φ(ω)·x(t-Δt) is the phase lag correction term, φ represents the phase corresponding to the excitation frequency ω, Represents the equivalent time delay.

[0091] The pressure loss in the pipeline is calculated segmentally, taking into account factors such as the length, diameter, roughness of the pipeline and the viscosity of the fluid. That is, the hydraulic pipeline factor is expressed by the following formula

[0092] ;

[0093] Among them, P i-loss It represents the pressure loss along the i-th section of the pipeline, that is, the friction force that hinders the movement of the fluid along the process, L i represents the length of the i-th pipeline, v i represents the dynamic viscosity in the i-th section of the pipeline, fi represents the equivalent friction coefficient, which is obtained from the following formula:

[0094] ;

[0095] Among them, R ei represents the Reynolds number of the i-th pipeline, , R ei <2000 indicates laminar flow, R ei >2000 indicates turbulence, λ i represents the wall roughness of the i-th section of pipeline;

[0096] Carefully study the fluid characteristics of components such as small orifices and throttle valves, including flow coefficients and pressure losses. Specifically, the hydraulic component characteristic factors include small orifice fluid characteristic factors and throttle valve fluid characteristic factors. Specifically, small orifice fluid characteristic factors include small orifice flow characteristics and small orifice local pressure loss.

[0097] The orifice flow characteristics are expressed by the following formula:

[0098] ;

[0099] Among them, Q s Indicates the flow rate of the small hole, C q represents the flow coefficient, Indicates the cross-sectional area of ​​the orifice;

[0100] The local pressure loss of the small hole is obtained by the following formula:

[0101] ;

[0102] in, Indicates the local pressure loss of the small hole.

[0103] The fluid characteristic factors of the throttle valve include the flow characteristics of the throttle valve and the local pressure loss of the throttle valve;

[0104] The flow characteristics of the throttle valve are expressed by the following formula:

[0105] ;

[0106] Among them, Q j represents the flow rate of the throttle valve, A(x) represents the cross-sectional area of ​​the valve port, and x represents the displacement of the valve core;

[0107] The local pressure loss of the throttle valve is expressed by the following formula:

[0108] .

[0109] in, is the local pressure loss coefficient of the throttle valve.

[0110] Analyze the relationship between the motor's voltage, current, speed, torque, and mechanical motion. The motor factor is expressed as follows:

[0111] The relationship between the voltage, current and speed of a permanent magnet synchronous motor is described in the rotating coordinate system (dq coordinate system):

[0112] ;

[0113] in, and Respectively represent the voltage of the d-axis and q-axis of the motor in the rotating coordinate system, represents the stator resistance, t represents the time, and Respectively represent the current of the motor on the d-axis and q-axis in the rotating coordinate system, and They represent the inductance of the motor along the d-axis and q-axis in the rotating coordinate system, represents the electrical angular velocity of the motor, represents the permanent magnet flux of the motor;

[0114] The torque equation of the motor is:

[0115]

[0116] in, represents the torque of the motor, and p represents the number of pole pairs;

[0117] The mechanical motion equation of the motor is:

[0118] ;

[0119] in, represents the load torque of the motor, J represents the moment of inertia, B represents the viscous friction coefficient, Indicates the mechanical angular velocity of the motor.

[0120] In some embodiments, the process of constructing a refined model of a hydraulic-electric active suspension includes: constructing a hydraulic-electric active suspension model that integrates nonlinear factors and hydraulic component characteristics, that is, using high-order differential equations to describe the flow and pressure of the hydraulic cylinder, and the dynamic changes of the voltage and speed of the motor to obtain a refined model, and using a system identification algorithm to estimate the model parameters of the refined model.

[0121] In the embodiment of the present invention, taking the pump type active suspension as an example, Figure 6 and Figure 7 , the refined model has the following formula:

[0122] ;

[0123] ;

[0124] ;

[0125] ;

[0126] ;

[0127] ;

[0128] ;

[0129] ;

[0130] in, and are the sprung and unsprung masses of the suspension, and are the suspension stiffness and tire stiffness, 、 and are the sprung mass displacement, unsprung mass displacement and road elevation, represents the sprung mass displacement The second derivative of represents the sprung mass displacement The first derivative of represents the unsprung mass displacement The first derivative of represents the unsprung mass displacement The second derivative of is the active suspension actuator force, k 缸 It represents the output force correction coefficient due to factors such as hydraulic cylinder friction, leakage and oil compressibility, P A1 and P B1 The oil pressure at the position of pipe A1 and B1 is r 泵理想 Indicates the ideal speed of the pump (or motor), r 泵实际 Indicates the actual speed of the pump (or motor), k 电机 It represents the correction coefficient of the mismatch between the expected and actual speed of the motor due to factors such as its internal control and load influence. k2 represents the influence of factors such as small holes and pipelines on the flow at A2 and B2. v 泵 Indicates the displacement of the pump (or motor), Q A1 and Q A2 Flow rate at pipes A1 and A2, Q B1 and Q AB2 The flow rate at the pipes B1 and B2, k1 represents the influence of factors such as small holes and pipelines on the flow rate at A1 and B1, and P represents the pressure at pipe A. (0) and (A) represents the density of the liquid at no pressure and at the pressure at pipe A, vol A Indicates the solution volume at position A1 or A2, V B It represents the bulk modulus of the liquid, where the correction coefficient can be theoretically deduced based on the above nonlinear factors and calibrated by experiments.

[0131] Through the function mapping relationship, the above nonlinear factors and hydraulic component characteristics are converted into functions of state variables, thereby accurately reflecting the nonlinear behavior of the system.

[0132] This method applies known input signals to the hydraulic and motor systems, measures the system's output responses, and then uses system identification algorithms (such as least squares and maximum likelihood methods) to estimate the system's model parameters. This approach does not require a deep understanding of the system's physical mechanisms, but rather builds a model based on experimental data.

[0133] S2: Decouple the refined model established in step S1 and conduct simulation experiments on the electrohydraulic active suspension to obtain basic vectors for describing the active suspension from the theoretical basic vectors obtained from the decoupling. In the present invention, theoretical derivation is combined with experimental verification to obtain basic vectors.

[0134] In some embodiments, step S2 includes:

[0135] S21: Determine the mathematical relationship between the motion parameters of the vehicle when it travels over the road surface and the dynamic response of the electrohydraulic active suspension based on the key parameters of the electrohydraulic active suspension and the load input. Step S21 includes:

[0136] Based on the principles of fluid mechanics, electricity, and mechanical dynamics, a first mathematical relationship between the load input of the electrohydraulic active suspension and the dynamic response of the electrohydraulic active suspension is obtained;

[0137] Based on the principles of vehicle dynamics and tire dynamics, a second mathematical relationship between the motion parameters of the vehicle as it travels over the road surface and the load input of the hydro-electric active suspension is obtained;

[0138] The mathematical relationship between the motion parameter and the dynamic response is obtained by combining the first mathematical relationship obtained in step S21 and the second mathematical relationship obtained in step S22.

[0139] S22: Decoupling the refined model using a differential geometry decoupling method for the mathematical relationship obtained in step S1 to obtain theoretical basic vectors for describing the active suspension.

[0140] In the embodiment of the present invention, a vertical two-degree-of-freedom vehicle model with active suspension is taken as an example:

[0141] The vehicle vibration model is:

[0142] ;

[0143] ;

[0144] Its state space is represented as: state variables ,

[0145] Output , at this time, the active suspension system can be rewritten as the following nonlinear form:

[0146] ;

[0147] in:

[0148] ;

[0149] By differentiating each term in each output y until the input u appears, it is easy to obtain a total relative order of 4, which satisfies the decoupling condition.

[0150] Then the decoupling matrix D(x) is composed of the derivatives of the second-order derivatives of the output with respect to the input:

[0151] ;

[0152] If the decoupling matrix D(x) is reversible, the active suspension system can be completely decoupled, and input-output linearization can be achieved through nonlinear feedback, as shown in the following formula:

[0153] ;

[0154] Among them, E .

[0155] Further we get:

[0156] ;

[0157] After decoupling, the closed-loop active suspension system dynamics is ,

[0158] Body displacement and wheel displacement Decoupled into two independent integrators.

[0159] S23: Based on the theoretical basic vector obtained in step S22, a sensitivity test analysis is performed on the vehicle, and multiple parameters in the theoretical basic vector that have the greatest impact on the high-frequency response characteristics of the suspension are combined into a basic vector.

[0160] In this embodiment of the present invention, simulation experiments using the AMESIM simulation platform, including single-step, sinusoidal, swept-frequency, and random road excitation inputs, were designed and implemented to investigate the suspension's response data under various excitations and verify the correctness of the theoretical derivation. The experimental data were used to modify the model parameters to ensure the accuracy of the basis vectors. A sensitivity analysis of the theoretical basis vectors was performed to identify the multiple parameters that most significantly influence the suspension's high-frequency response characteristics, forming the basis vectors. This provided a basis for subsequent model optimization.

[0161] The present invention analyzes the sensitivity of system parameters to suspension response and selects parameters that have a greater impact on the suspension's high-frequency response characteristics as the model's basic vectors. This method can more directly reflect the impact of system parameters on suspension performance.

[0162] S3: Apply high-frequency excitation to the electrohydraulic active suspension and determine a preliminary high-frequency response model of the electrohydraulic active suspension.

[0163] In some embodiments, step S3 includes:

[0164] Perform time and frequency domain analysis on a hydro-electric active suspension subjected to high-frequency excitation to obtain high-frequency characteristic parameters describing amplitude attenuation and phase lag in the high-frequency band.

[0165] Based on the high-frequency characteristic parameters, the excitation frequency of the high-frequency excitation and the system parameters of the electrohydraulic active suspension, a preliminary high-frequency response model is fitted using the statistical learning method.

[0166] In an embodiment of the present invention, technical means such as time domain and frequency domain analysis are used to conduct an in-depth study of the dynamic behavior of the hydraulic-electric active suspension under high-frequency excitation. High-frequency characteristic parameters such as resonance frequency and damping ratio are extracted to describe key characteristics of the hydraulic-electric active suspension, such as high-frequency amplitude attenuation and phase lag. Based on the high-frequency characteristic parameters, as well as the excitation frequency of the high-frequency excitation and the system parameters of the hydraulic-electric active suspension, a preliminary high-frequency response model is fitted using statistical learning methods such as regression analysis and neural networks. The present invention replaces complex physical models by constructing proxy models (such as response surface models, neural network models, etc.), thereby improving the model solution speed while ensuring a certain level of accuracy. This method can significantly reduce the computational complexity of the model while ensuring model accuracy.

[0167] S4: Using the basic vectors obtained in step S2, the preliminary high-frequency response model of step S3 is fitted and optimized to obtain a high-frequency response characteristic model of the electro-hydraulic active suspension.

[0168] In some embodiments, the basic vectors are used in combination with an optimization algorithm to perform fitting optimization on the preliminary high-frequency response model to obtain a high-frequency response characteristic model.

[0169] In some embodiments, step S4 further includes simplifying the preliminary high-frequency response model using a model order reduction technique to reduce the complexity of the preliminary high-frequency response model.

[0170] It will be appreciated that in an embodiment of the present invention, step S4 includes simplifying the preliminary high-frequency response model using a model order reduction technique. Specifically, a model order reduction technique using modal truncation or balanced truncation is used to reduce the complexity of the model while ensuring model accuracy. The simplified preliminary high-frequency response model is then fitted and optimized using a basis vector in combination with an optimization algorithm to obtain a high-frequency response characteristic model. The optimization algorithm may be a genetic algorithm or a particle swarm algorithm, and the present invention does not limit the optimization algorithm.

[0171] In order to illustrate the beneficial effects of the method for constructing the high-frequency response characteristic model of the hydraulic-electric active suspension provided by the present invention, simulation analysis and experimental verification were carried out. The embodiment of the present invention uses AMESIM and MATLAB / Simulink simulation platforms to simulate and analyze the high-frequency response characteristic model and evaluate the solution speed and accuracy of the model. The AMESIM simulation of the hydraulic cylinder is as follows: Figure 7 As shown. Experimental verification is carried out on typical working conditions such as step working conditions, random road working conditions, and frequency sweeping working conditions. The model prediction results are compared with the experimental data, and the output force-time in the time domain and the amplitude-frequency characteristics and phase-frequency characteristics in the frequency domain are analyzed to ensure the feasibility and effectiveness of the model in practical applications. The embodiment of the present invention also conducts a robustness and adaptability analysis of the high-frequency response characteristic model. Specifically, the robustness and adaptability of the model under different working conditions and different parameter conditions are analyzed to ensure that the model can be widely applied to various hydraulic active suspension systems. The experimental results are shown in Figures 8 to 10 ,in, Figure 8 It can be seen that the expected force and the actual force of the active suspension follow each other. Figure 9 and Figure 10 The Bode diagram of the system response shows that the constructed hydraulic active suspension model can characterize the system's time domain hysteresis and frequency domain amplitude-frequency response and phase-frequency response characteristics.

[0172] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0173] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension, characterized in that: include: S1: Based on the nonlinear factors of the electrohydraulic active suspension, a refined model of the vertical two-degree-of-freedom vehicle model with electrohydraulic active suspension is constructed; S2: Decoupling the refined model established in step S1, and conducting a simulation experiment on the electrohydraulic active suspension, obtaining a basic vector for describing the active suspension from the theoretical basic vector obtained by decoupling, wherein the theoretical basic vector and elements in the basic vector reflect the state of the active suspension; S3: applying high-frequency excitation to the electrohydraulic active suspension and determining a preliminary high-frequency response model of the electrohydraulic active suspension; S4: Using the basic vectors obtained in step S2, the preliminary high-frequency response model of step S3 is fitted and optimized to obtain a high-frequency response characteristic model of the electrohydraulic active suspension.

2. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 1, characterized in that: The nonlinear factors in step S1 include friction factors of the hydraulic cylinder, oil leakage factors, oil compression factors, hydraulic pipeline factors, hydraulic component characteristic factors, and motor factors of the active suspension; wherein: The friction factor is expressed by the following formula: F fiction =μ·(P·A)·sign(v)+b·v; Among them, F fiction represents the friction force of the hydraulic cylinder, μ represents the friction coefficient, P represents the working pressure, A represents the effective area of ​​the piston in the hydraulic cylinder, v represents the movement speed of the piston in the hydraulic cylinder, b represents the viscous friction coefficient of the lubricating fluid in the hydraulic cylinder, and α represents the temperature correction factor; The oil leakage factor is expressed by the following formula: Q=K·ΔP·e αT ; Where K represents the total correction factor and ΔP represents the working pressure difference; The oil compressibility factor is expressed by the following formula: ； Among them, K eff represents the effective elastic modulus of the gas-containing oil; B represents damping, ρ represents the fluid density of the oil, c represents the pressure wave velocity, L represents the length of the pipeline through which the oil flows, ω represents the excitation frequency, ΔP res represents the peak value of pressure fluctuation caused by oil compressibility, φ represents the phase corresponding to the excitation frequency ω, represents the equivalent time delay; The hydraulic line factor is expressed by the following formula ； Among them, P i-loss It represents the pressure loss along the i-th section of pipeline, L i represents the length of the i-th pipeline, v i represents the dynamic viscosity in the i-th section of the pipeline, f i It is obtained from the following formula: ； Among them, R ei represents the Reynolds number of the i-th pipeline, λ i represents the wall roughness of the i-th section of pipeline; The hydraulic element characteristic factors include small hole fluid characteristic factors and throttle valve fluid characteristic factors; The motor factors include the relationship between the voltage, current and speed of the motor of the active suspension, the torque condition and the mechanical motion condition.

3. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: The small hole fluid characteristic factors include small hole flow characteristics and small hole local pressure loss; The orifice flow characteristics are expressed by the following formula: ； Among them, Q s Indicates the flow rate of the small hole, C q represents the flow coefficient, A represents the orifice cross-sectional area, The local pressure loss of the small hole is obtained by the following formula: ； in, Indicates the local pressure loss of the small hole.

4. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: The throttle valve fluid characteristic factors include the flow characteristics of the throttle valve and the local pressure loss of the throttle valve; The flow characteristics of the throttle valve are expressed by the following formula: ； Among them, Q j represents the flow rate of the throttle valve, A(x) represents the orifice cross-sectional area; The local pressure loss of the throttle valve is expressed by the following formula: 。 5. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: In step S1, the process of constructing a refined model of the electro-hydraulic active suspension includes: The refined model is obtained by using high-order differential equations to describe the flow and pressure of the hydraulic cylinder and the dynamic changes of the current and speed of the motor, and the model parameters of the refined model are estimated using a system identification algorithm.

6. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: Step S2 includes: S21: determining a mathematical relationship between a motion parameter of the vehicle when traversing a road surface and a dynamic response of the electrohydraulic active suspension based on key parameters of the electrohydraulic active suspension and a load input; S22: Based on the mathematical relationship obtained in step S21, decoupling the refined model using a differential geometry decoupling method to obtain theoretical basic vectors for describing the active suspension; S23: Based on the theoretical basic vector obtained in step S22, a sensitivity experimental analysis is performed on the vehicle, and multiple parameters in the theoretical basic vector that have the greatest impact on the high-frequency response characteristics of the suspension are combined into the basic vector.

7. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 6, characterized in that: Step S21 includes: Based on the principles of fluid mechanics, electricity, and mechanical dynamics, a first mathematical relationship between a load input of the electrohydraulic active suspension and a dynamic response of the electrohydraulic active suspension is obtained; Based on vehicle dynamics and tire dynamics principles, a second mathematical relationship between the motion parameter and the load input of the electrohydraulic active suspension is obtained; The mathematical relationship between the motion parameter and the dynamic response is obtained by combining the first mathematical relationship obtained in step S21 and the second mathematical relationship obtained in step S22.

8. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: Step S3 includes: Perform time and frequency domain analysis on a hydro-electric active suspension subjected to high-frequency excitation to obtain high-frequency characteristic parameters describing amplitude attenuation and phase lag in the high-frequency band. Based on the high-frequency characteristic parameters, the excitation frequency of the high-frequency excitation, and the system parameters of the electrohydraulic active suspension, the preliminary high-frequency response model is obtained by fitting using a statistical learning method.

9. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 2, characterized in that: In step S4: the basic vectors are used in combination with an optimization algorithm to perform fitting optimization on the preliminary high-frequency response model to obtain the high-frequency response characteristic model.

10. The method for constructing a high-frequency response characteristic model of a hydraulic-electric active suspension according to claim 9, characterized in that: Step S4 further includes simplifying the preliminary high-frequency response model using a model order reduction technique to reduce the complexity of the preliminary high-frequency response model.

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