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

Abstract

The invention relates to the technical field of automobile control, in particular to a method for constructing a high-frequency response characteristic model of a liquid-electric active suspension, which comprises the following steps of: constructing a refined model of the liquid-electric active suspension according to nonlinear factors of the liquid-electric active suspension; decoupling the established refined model, performing a simulation experiment on the electro-hydraulic active suspension, and obtaining a basic vector used for describing the active suspension from theoretical basic vectors obtained by decoupling; applying high-frequency excitation to the electrohydraulic active suspension, and determining a preliminary high-frequency response model of the electrohydraulic active suspension; and performing fitting optimization on the preliminary high-frequency response model by using the obtained basic vector to obtain a high-frequency response characteristic model of the electro-hydraulic active suspension. The method disclosed by the invention reveals the internal relation between the system parameters and the high-frequency response characteristics through a mode of combining theoretical analysis and experimental verification, and constructs an accurate and efficient model.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control, and particularly relates to a method for constructing a high-frequency response characteristic model of a hydroelectric active suspension. Background Art

[0002] During vehicle driving, due to the influence of factors such as road surface inequality, the vehicle will vibrate, the vehicle attitude will change, affecting the vertical tire force, and changing the ride comfort and handling stability of the vehicle. The hydroelectric active suspension can effectively control vehicle vibration and body attitude, and improve the ride comfort and handling stability of the vehicle 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 hydroelectric active suspension uses electric energy - kinetic energy - liquid pressure energy as the energy transfer link. The motor of the hydroelectric active suspension converts the electric energy of the vehicle into kinetic energy, the motor is linked with the hydraulic pump to convert kinetic energy into liquid pressure energy, and the force is transmitted to the unsprung mass and sprung mass through the hydraulic cylinder, thereby realizing the active control of the vertical motion state of the vehicle.

[0003] Currently, the modeling methods of active suspensions focus on the modeling of electromechanical active suspensions. The invention patent application with the Chinese patent publication number CN115828419A, publication date of March 21, 2023, and patent name "A Method for Modeling an Electromechanical Active Suspension" has established a complete mathematical model of an electromechanical active suspension in the kinematic field and the dynamic field; while for the hydroelectric active suspension, it is mainly modeled through software based on characteristic solution and software based on finite element solution. The existing technologies mainly have the following deficiencies: (1) High complexity of model solution: The hydroelectric active suspension system involves multiple non-linear links, such as the friction of the hydraulic cylinder, the compressibility of the oil, the dynamic characteristics of the pipeline fluid, and the electromagnetic and mechanical characteristics of the motor, etc., resulting in complex calculation of the accurate model and difficult real-time solution, which limits its wide application in vehicle dynamic control; (2) Unclear relationship between system parameters and high-frequency response characteristics: High-frequency vibration is an important part that cannot be ignored during vehicle driving, and has an important impact on ride comfort and vehicle stability. However, existing models often fail to directly reveal the clear relationship between model parameters (such as the structural form 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 in design optimization, fault diagnosis, and performance evaluation. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method for constructing a high-frequency response characteristic model of a hydroelectric active suspension to meet the real-time solution requirements of the high-frequency response characteristics of the hydroelectric active suspension, and to reveal the influence mechanism between system parameters and the high-frequency response characteristics of the active suspension, ensuring the accuracy and rapid solution of the model.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A method for constructing a high-frequency response characteristic model of a hydroelectric active suspension, comprising: S1: Construct a refined model of the hydroelectric active suspension according to the nonlinear factors of the hydroelectric active suspension; S2: Decouple the refined model established in step S1, and conduct a simulation experiment on the hydroelectric active suspension to obtain the basic vectors for describing the active suspension from the theoretically basic vectors obtained by decoupling; S3: Apply a high-frequency excitation to the hydroelectric active suspension and determine the preliminary high-frequency response model of the hydroelectric active suspension; S4: Use the basic vectors obtained in step S2 to fit and optimize the preliminary high-frequency response model in step S3 to obtain the high-frequency response characteristic model of the hydroelectric active suspension.

[0006] Further, the nonlinear factors in step S1 include the friction factor of the hydraulic cylinder, the oil leakage factor, the oil compression factor, the hydraulic pipeline factor, the characteristics factor of hydraulic components, and the motor factor of the active suspension; among them: The friction factor is expressed by the following formula: F fiction =μ·(P·A)·sign(v)+b·v; Wherein, F fiction represents the frictional 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 moving speed of the piston in the hydraulic cylinder, and b represents the viscous friction coefficient of the lubricating fluid in the hydraulic cylinder; The oil leakage factor is expressed by the following formula: Q=K·ΔP·e αT ; Wherein, K represents the total correction factor, and ΔP represents the working pressure difference; The oil compression factor is expressed by the following formula: ; Wherein, K eff represents the effective elastic modulus of the gas-containing oil, B represents the damping, ρ represents the fluid density of the oil, c represents the pressure wave speed, L represents the length of the pipeline through which the oil flows, ω represents the excitation frequency, ΔP res represents the peak value of the pressure fluctuation caused by the oil compressibility, φ represents the phase corresponding to the excitation frequency ω, represents the equivalent time delay; The hydraulic pipeline factor is expressed by the following formula ; Wherein, P i-lossDenote the frictional pressure loss in the $i$-th pipeline section, $L$ i Denote the pipe length of the $i$-th pipeline section, $v$ i Denote the dynamic viscosity in the $i$-th pipeline section, $f$ i Obtained from the following formula: ; where, $R$ ei Denote the Reynolds number of the $i$-th pipeline section, $\lambda$ i Denote the pipe wall roughness of the $i$-th pipeline section; The characteristics factors of hydraulic components include the characteristics factors of orifice fluid and the characteristics factors of throttle valve fluid; 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.

[0007] Furthermore, the characteristics factors of orifice fluid include the orifice flow characteristics and the local pressure loss of the orifice; The orifice flow characteristics are expressed by the following formula: ; where, $Q$ s Denote the flow rate of the orifice, $C$ q Denote the flow coefficient, $A$ denotes the orifice cross-sectional area, The local pressure loss of the orifice is obtained from the following formula: ; where, Denote the local pressure loss of the orifice.

[0008] Furthermore, the characteristics factors of throttle valve fluid 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: ; where, $Q$ j Denote the flow rate of the throttle valve, $A(x)$ denotes the orifice cross-sectional area; The local pressure loss of the throttle valve is expressed by the following formula: .

[0009] Furthermore, in step S1, the process of constructing the refined model of the hydroelectric active suspension includes: Describing the flow rate and pressure of the hydraulic cylinder and the dynamic changes of the current and speed of the motor by using high-order differential equations, obtaining the refined model, and estimating the model parameters of the refined model by using the system identification algorithm.

[0010] Furthermore, step S2 includes: S21: Determine the mathematical relationship between the motion parameters of the vehicle when passing through the road surface and the dynamic response of the hydroelectric active suspension according to the key parameters and load input of the hydroelectric active suspension; S22: Decouple the refined model using the differential geometry decoupling method for the mathematical relationship obtained in step S1 to obtain the theoretical basic vectors for describing the active suspension; S23: Based on the theoretical basic vectors obtained in step S22, conduct a sensitivity experiment analysis on the vehicle, and form basic vectors by combining multiple parameters in the theoretical basic vectors that have the greatest influence on the high-frequency response characteristics of the suspension.

[0011] Further, step S21 includes: Based on the principles of fluid mechanics, electrical principles, and mechanical dynamics, obtain the first mathematical relationship between the load input of the hydroelectric active suspension and the dynamic response of the hydroelectric active suspension; Based on the principles of vehicle dynamics and tire dynamics, obtain the second mathematical relationship between the motion parameters and the load input of the hydroelectric active suspension; Combine the first mathematical relationship obtained in step S21 and the second mathematical relationship obtained in step S22 to obtain the mathematical relationship between the motion parameters and the dynamic response.

[0012] Further, step S3 includes: Conduct time-domain and frequency-domain analyses on the hydroelectric active suspension subjected to high-frequency excitation to obtain high-frequency characteristic parameters for describing the amplitude attenuation and phase lag in the high-frequency band; Based on the high-frequency characteristic parameters, as well as the excitation frequency of the high-frequency excitation and the system parameters of the hydroelectric active suspension, use the statistical learning method to fit and obtain a preliminary high-frequency response model.

[0013] Further, in step S4: Use the basic vectors and combine the optimization algorithm to fit and optimize the preliminary high-frequency response model to obtain a high-frequency response characteristic model.

[0014] Further, in step S4, it also includes using the model reduction technology to simplify the preliminary high-frequency response model to reduce the complexity of the preliminary high-frequency response model.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The method for constructing the high-frequency response characteristic model of the hydroelectric active suspension described in the present invention extracts the key parameters of the hydroelectric active suspension model through a method combining theoretical derivation and experimental verification, and abstracts the basic vectors affecting the high-frequency excitation response characteristics of the hydroelectric active suspension model, providing a solid foundation for subsequent model construction and performance analysis; (2)The method for constructing the high-frequency response characteristic model of the hydroelectric active suspension according to the present invention creatively studies the dynamic behavior of the suspension under high-frequency excitation, abstracts key characteristics such as amplitude attenuation and phase lag in the high-frequency band, and provides an important basis for optimizing the suspension performance and developing intelligent control strategies; (3)The method for constructing the high-frequency response characteristic model of the hydroelectric active suspension according to the present invention creatively constructs a high-frequency response characteristic model with both solution speed and model accuracy by using basic vectors and the abstracted high-frequency response characteristics: (4)The method for constructing the high-frequency response characteristic model of the hydroelectric active suspension according to the present invention creatively combines model reduction technology, optimization algorithms, etc., and constructs a high-frequency response characteristic model of the hydroelectric active suspension that has both high solution speed and can ensure model accuracy by using the abstracted basic vectors and high-frequency response characteristics, solving the problem that it is difficult to balance solution speed and accuracy in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings forming a part of the present invention creatively provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a flowchart of the method for constructing the high-frequency response characteristic model of the hydroelectric active suspension according to the embodiment of the present invention; Figure 2 is a flowchart block diagram of step S1 according to the embodiment of the present invention; Figure 3 is a flowchart block diagram of step S2 according to the embodiment of the present invention; Figure 4 is a flowchart block diagram of step S3 according to the embodiment of the present invention; Figure 5 is a flowchart block diagram of step S4 according to the embodiment of the present invention; Figure 6 is a schematic diagram of the hydroelectric active suspension according to the embodiment of the present invention; Figure 7 is a schematic AMESIM simulation diagram of the hydraulic cylinder according to the embodiment of the present invention; Figure 8 is a curve graph of the force characteristics of the hydroelectric active suspension according to the embodiment of the present invention; Figure 9 is a Bode diagram of the frequency-domain response of the amplitude of the hydroelectric active suspension according to the embodiment of the present invention; Figure 10 is a Bode diagram of the frequency-domain response of the phase of the hydroelectric active suspension according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the following further describes the present invention in detail 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 to the present invention.

[0018] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0019] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and defined, the terms "mounted", "connected" and "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0021] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0022] As Figures 1 to 7 shown, the method for constructing a high-frequency response characteristic model of a liquid-electric active suspension according to an embodiment of the present invention includes: S1: Construct a refined model of the liquid-electric active suspension according to the non-linear factors of the liquid-electric active suspension.

[0023] In some embodiments, the non-linear factors in step S1 include the friction factor of the hydraulic cylinder, the oil leakage factor, the oil compression factor, the hydraulic pipeline factor, the characteristics factor of the hydraulic components, and the motor factor. Among them: Conduct a detailed analysis of the frictional force of the hydraulic cylinder, considering its variation laws with pressure and speed, that is: the friction factor is expressed by the following formula: F fiction =μ·(P·A)·sign(v)+b·v; Among them, F fiction represents the frictional force of the hydraulic cylinder, μ represents the friction coefficient, P represents the working pressure of the hydraulic cylinder (Pa), A represents the effective area of the piston in the hydraulic cylinder (m²), v represents the moving speed of the piston in the hydraulic cylinder (m / s), and b represents the viscous friction coefficient of the lubricating fluid in the hydraulic cylinder (N·s / m). The friction coefficient μ is related to the sealing material and surface roughness, and the viscous friction coefficient b is related to the lubricating fluid viscosity and clearance.

[0024] Deeply study the leakage problem of the hydraulic cylinder, including the variation relationship of the leakage amount with the pressure difference and oil temperature, that is: the oil leakage factor is expressed by the following formula: Q=K·ΔP·e αT ; Among them, Q represents the leakage flow rate, K represents the total correction factor, ΔP represents the working pressure difference between both sides of the piston (Pa), α is the temperature correction factor, and T is the temperature; Analyze the compressibility of the oil, especially the influence of the compressibility of the oil under high-frequency excitation on the system dynamic response, that is: the oil compression factor is expressed by the following formula: ; In the above formula, is the mechanical dynamics term, among which, K eff represents the effective elastic modulus of the oil containing gas; B represents the damping term caused by the compressibility of the oil; is the pressure fluctuation caused by the propagation of the flow excitation 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 the pressure fluctuation caused by the compressibility of the oil; 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.

[0025] Conduct a segmented calculation of the pressure loss in the pipeline, considering 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 ; Among them, P i-loss represents the frictional pressure loss along the i-th section of the pipeline, that is, the frictional force that hinders the fluid movement along the flow path, L iDenote the pipe length of the i-th pipe segment, v i Denote the dynamic viscosity in the i-th pipe segment, f i Denote the equivalent friction coefficient, obtained by the following formula: ; where, R ei Denote the Reynolds number of the i-th pipe segment, , R ei <2000 indicates laminar flow, R ei >2000 indicates turbulent flow, λ i Denote the pipe wall roughness of the i-th pipe segment; Carefully study the fluid characteristics of components such as small holes and throttle valves, including the flow coefficient and pressure loss, that is: the hydraulic component characteristic factors include the small hole fluid characteristic factors and the throttle valve fluid characteristic factors. Specifically, the small hole fluid characteristic factors include the small hole flow characteristics and the local pressure loss of the small hole; The small hole flow characteristics are expressed by the following formula: ; where, Q s Denote the flow rate of the small hole, C q Denote the flow coefficient, Denote the orifice cross-sectional area; The local pressure loss of the small hole is obtained by the following formula: ; where, Denote the local pressure loss of the small hole.

[0026] The throttle valve fluid characteristic factors include the throttle valve flow characteristics and the local pressure loss of the throttle valve; The throttle valve flow characteristics are expressed by the following formula: ; where, Q j Denote the flow rate of the throttle valve, A(x) denotes the valve port cross-sectional area, and x denotes the spool displacement; The local pressure loss of the throttle valve is expressed by the following formula: .

[0027] where, Is the local pressure loss coefficient of the throttle valve.

[0028] Analyze the relationship between the voltage, current and speed of the motor, the torque situation and the mechanical motion situation, that is: the motor factors are expressed by the following formula: Describe the relationship between the voltage, current and speed of the permanent magnet synchronous motor in the rotating coordinate system (d-q coordinate system) as: ; Among them, and respectively represent the voltages on the d-axis and q-axis of the motor in the rotating coordinate system, represents the stator resistance, t represents time, and respectively represent the currents on the d-axis and q-axis of the motor in the rotating coordinate system, and respectively represent the inductances on the d-axis and q-axis of the motor in the rotating coordinate system, represents the electrical angular velocity of the motor, represents the permanent magnet flux linkage of the motor; The torque equation of the motor is:

[0029] Among them, represents the torque of the motor, p represents the number of pole pairs; The mechanical motion equation of the motor is: ; Among them, represents the load torque of the motor, J represents the moment of inertia, B represents the viscous friction coefficient, represents the mechanical angular velocity of the motor.

[0030] In some embodiments, the process of constructing a refined model of a hydro-pneumatic active suspension includes: constructing a hydro-pneumatic active suspension model that incorporates comprehensive non-linear factors and the characteristics of hydraulic components, that is, using high-order differential equations to describe the flow rate and pressure of the hydraulic cylinder, as well as the dynamic changes in the voltage and rotational speed of the motor, to obtain a refined model, and using a system identification algorithm to estimate the model parameters of the refined model.

[0031] In the embodiments of the present invention, taking the pump-type active suspension as an example, combined with Figure 6 and Figure 7 , the refined model has the following formula: ; ; ; ; ; ; ; ; Among them, and are the unsprung and sprung masses of the suspension, and are the suspension stiffness and the tire stiffness, , and are the displacement of the unsprung mass, the displacement of the sprung mass, and the road surface elevation, represents the second derivative of the displacement of the sprung mass , represents the first derivative of the displacement of the sprung mass , represents the first derivative of the displacement of the unsprung mass , represents the second derivative of the displacement of the unsprung mass , is the actuation force of the active suspension actuator, k 缸 represents the output force correction coefficient affected by factors such as hydraulic cylinder friction, leakage, and oil compressibility, P A1 and P B1 are the hydraulic pressures at the positions of pipelines A1 and B1, r 泵理想 represents the ideal rotational speed of the pump (or motor), r 泵实际 represents the actual rotational speed of the pump (or motor), k 电机 represents the correction coefficient for the mismatch between the expected and actual rotational speeds of the motor due to factors such as its internal control and load influence, k 2 represents the influence of factors such as small holes and pipelines on the flow rates at A2 and B2, v 泵 represents the displacement of the pump (or motor), Q A1 and Q A2 are the flow rates at the positions of pipelines A1 and A2, Q B1 and Q AB2 are the flow rates at the positions of pipelines B1 and B2, k 1 represents the influence of factors such as small holes and pipelines on the flow rates at A1 and B1, P represents the pressure at pipeline A, (0) and (A) represent the liquid densities under no pressure and the pressure at pipeline A, vol A represents the calculated volume at the position of A1 or A2, V B represents the bulk modulus of the liquid, where the correction coefficients can all be calibrated through theoretical derivation based on the above non - linear factors and by means of experiments.

[0032] Through the function mapping relationship, the above non - linear factors and factors such as the characteristics of hydraulic components are transformed into functions of state variables, so as to accurately reflect the non - linear behavior of the system.

[0033] The present invention applies known input signals to the hydraulic system and the motor system, measures the output response of the system, and then uses system identification algorithms (such as the least squares method, the maximum likelihood method, etc.) to estimate the model parameters of the system. This method does not require in-depth understanding of the physical mechanism of the system, but constructs the model through experimental data.

[0034] S2: Decouple the refined model established in step S1, and conduct a simulation experiment on the hydroelectric active suspension to obtain the basic vectors for describing the active suspension from the theoretically derived basic vectors. In the present invention, the theoretical derivation and experimental verification are combined to obtain the basic vectors.

[0035] In some embodiments, step S2 includes: S21: Determine the mathematical relationship between the motion parameters of the vehicle when passing through the road surface and the dynamic response of the hydroelectric active suspension according to the key parameters and load input of the hydroelectric active suspension. Among them, step S21 includes: Based on the principles of fluid mechanics, electrical principles, and mechanical dynamics, obtain the first mathematical relationship between the load input of the hydroelectric active suspension and the dynamic response of the hydroelectric active suspension; Based on the principles of vehicle dynamics and tire dynamics, obtain the second mathematical relationship between the motion parameters of the vehicle when passing through the road surface and the load input of the hydroelectric active suspension; Combine the first mathematical relationship obtained in step S21 and the second mathematical relationship obtained in step S22 to obtain the mathematical relationship between the motion parameters and the dynamic response.

[0036] S22: Use the differential geometry decoupling method to decouple the refined model for the mathematical relationship obtained in step S1 to obtain the theoretically derived basic vectors for describing the active suspension.

[0037] In the embodiments of the present invention, taking the vertical two-degree-of-freedom vehicle model with an active suspension as an example: The vehicle vibration model is: ; ; Its state space representation is: state variables , Output , at this time, the active suspension system can be rewritten into the following non-linear form: ; Among them: ; Derive each term in each output y until the input u appears, and it is easy to obtain that the total relative order is 4, meeting the decoupling condition.

[0038] The decoupling matrix D(x) is composed of the derivative of the second-order derivative of the output with respect to the input: ; If the decoupling matrix D(x) is invertible, the active suspension system can be completely decoupled, and then input-output linearization can be achieved through non-linear feedback, as shown in the following equation: ; where, E .

[0039] Furthermore, it can be obtained that: ; After decoupling, the dynamics of the closed-loop active suspension system are ,

[0040] That is, the body displacement and the wheel displacement are decoupled into two independent integrators.

[0041] S23: Based on the theoretical basic vectors obtained in step S22, perform a sensitivity experiment analysis on the vehicle, and form basic vectors by combining multiple parameters that have the greatest influence on the high-frequency response characteristics of the suspension in the theoretical basic vectors.

[0042] In the embodiments of the present invention, based on the AMESIM simulation platform, simulation experiments such as a step, sine, sweep frequency, and random road surface excitation input are designed and implemented to explore the response data of the suspension under different excitations, and to verify the correctness of the theoretical derivation. The model parameters are corrected using the experimental data to ensure the accuracy of the basic vectors. Perform a sensitivity analysis of the theoretical basic vectors to identify multiple parameters that have the greatest influence on the high-frequency response characteristics of the suspension and form basic vectors, providing a basis for subsequent model optimization.

[0043] The present invention selects parameters that have a greater influence on the high-frequency response characteristics of the suspension as the basic vectors of the model by analyzing the sensitivity of system parameters to the suspension response. This method can more directly reflect the influence of system parameters on the suspension performance.

[0044] S3: Apply a high-frequency excitation to the hydroelectric active suspension and determine the preliminary high-frequency response model of the hydroelectric active suspension.

[0045] In some embodiments, step S3 includes: Perform time-domain and frequency-domain analyses on the hydroelectric active suspension subjected to high-frequency excitation to obtain high-frequency characteristic parameters for describing amplitude attenuation and phase lag in the high-frequency band; Based on the high-frequency characteristic parameters, as well as the excitation frequency of the high-frequency excitation and the system parameters of the hydroelectric active suspension, use statistical learning methods to fit and obtain a preliminary high-frequency response model.

[0046] In the embodiments of the present invention, by means of technical means such as time-domain and frequency-domain analysis, the dynamic behavior of the hydroelectric active suspension under high-frequency excitation is deeply studied. High-frequency characteristic parameters describing the key characteristics of the hydroelectric active suspension, such as amplitude attenuation and phase lag in the high-frequency band, are extracted, such as resonance frequency, damping ratio, etc. Based on the high-frequency characteristic parameters, the excitation frequency of the high-frequency excitation, and the system parameters of the hydroelectric active suspension, preliminary high-frequency response models are obtained by fitting using statistical learning methods such as regression analysis and neural networks. In the present invention, a surrogate model (such as a response surface model, a neural network model, etc.) is constructed to replace the complex physical model, thereby improving the solution speed of the model on the premise of ensuring a certain accuracy. This method can significantly reduce the computational complexity of the model while ensuring the accuracy of the model.

[0047] S4: Use the basic vectors obtained in step S2 to fit and optimize the preliminary high-frequency response model in step S3 to obtain the high-frequency response characteristic model of the hydroelectric active suspension.

[0048] In some embodiments, the preliminary high-frequency response model is fitted and optimized by using the basic vectors in combination with an optimization algorithm to obtain the high-frequency response characteristic model.

[0049] In some embodiments, step S4 further includes simplifying the preliminary high-frequency response model by using model order reduction technology to reduce the complexity of the preliminary high-frequency response model.

[0050] It can be understood that in the embodiments of the present invention, step S4 includes: simplifying the preliminary high-frequency response model by using model order reduction technology. Specifically, model order reduction technologies such as modal truncation or balanced truncation are adopted to reduce the complexity of the model on the premise of ensuring the accuracy of the model. The simplified preliminary high-frequency response model is fitted and optimized by using the basic vectors in combination with an optimization algorithm to obtain the high-frequency response characteristic model, where the optimization algorithm can be a genetic algorithm or a particle swarm algorithm, and the present invention does not limit the optimization algorithm.

[0051] To illustrate the beneficial effects of the method for constructing the high-frequency response characteristic model of the hydroelectric active suspension provided by the present invention, simulation analysis and experimental verification are carried out. In the embodiments of the present invention, the AMESIM and MATLAB / Simulink simulation platforms are used to perform simulation analysis on the high-frequency response characteristic model to evaluate the solution speed and accuracy of the model. The AMESIM simulation of the hydraulic cylinder is as Figure 7As shown. Design and conduct experiments to verify typical working conditions such as step working conditions, random road surface conditions, and swept-frequency working conditions. Compare the model prediction results with the experimental data, and analyze the output force-time in the time domain and the amplitude-frequency characteristics and phase-frequency characteristics in the frequency domain to ensure the feasibility and effectiveness of the model in practical applications. The embodiments of the present invention also conduct robustness and adaptability analysis of the high-frequency response characteristic model. Specifically, analyze the robustness and adaptability of the model under different working conditions and different parameter conditions to ensure that the model can be widely applied to various electro-hydraulic active suspension systems. The experimental results are as Figures 8 to 10 , where Figure 8 it can be seen the following situation of the expected force and the actual force of the active suspension, Figure 9 and Figure 10 are the Bode diagrams of the system response, which can reflect that the constructed electro-hydraulic active suspension model can characterize the time-domain hysteresis and the amplitude-frequency response and phase-frequency response characteristics in the frequency domain of the system.

[0052] It should be understood that various forms of the processes shown above can be used, reordering, adding or deleting steps. For example, the steps recorded in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present invention can be achieved, and no limitations are imposed herein.

[0053] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope 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 hydraulic-electric active suspension, a refined model of the hydraulic-electric active suspension is constructed; S2: decoupling the refined model established in step S1, and conducting a simulation experiment on the hydraulic-electric active suspension, and obtaining a basic vector for describing the active suspension from the theoretical basic vectors obtained by decoupling; S3: applying high-frequency excitation to the hydraulic-electric active suspension, and determining a preliminary high-frequency response model of the hydraulic-electric active suspension; S4: using the basic vectors obtained in step S2 to perform fitting optimization on the preliminary high-frequency response model of step S3, to obtain a high-frequency response characteristic model of the hydraulic-electric 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, and b represents the viscous friction coefficient of the lubricating fluid in the hydraulic cylinder; 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 represents the pressure loss along the i-th section of the 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, the torque and the mechanical movement of the motor of the active suspension.

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 characteristic is 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, Represents the local pressure loss of a 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 cross-sectional area of ​​the orifice; 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 hydraulic-electric 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 rotation 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 a vehicle passing through a road surface and a dynamic response of the hydraulic-electric active suspension according to key parameters of the hydraulic-electric active suspension and a load input; S22: Decoupling the refined model using a differential geometry decoupling method for the mathematical relationship obtained in step S1, to obtain a theoretical basic vector 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 a plurality of 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 the load input of the electric-hydraulic active suspension and the dynamic response of the electric-hydraulic active suspension is obtained; Based on the vehicle dynamics principle and the tire dynamics principle, a second mathematical relationship between the motion parameter and the load input of the hydraulic-electric 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: The time domain and frequency domain analysis of the hydraulic-electric active suspension with high-frequency excitation is performed to obtain high-frequency characteristic parameters used to describe the 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 hydraulic-electric active suspension, the preliminary high-frequency response model is fitted by 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 also includes simplifying the preliminary high-frequency response model by using a model order reduction technique to reduce the complexity of the preliminary high-frequency response model.

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