Time-lag acceleration feedback control method for improving vehicle driving smoothness

Abstract

The invention relates to a time-delay acceleration feedback control method for improving vehicle driving smoothness. The time-delay acceleration feedback control method comprises the steps that a target vehicle active suspension mathematical model under time-delay acceleration feedback control is established; based on the target vehicle active suspension mathematical model, sprung mass, suspension dynamic stroke and tire dynamic load under simple harmonic road excitation are obtained; establishing a characteristic model of the suspension system, and obtaining a relation curve of a feedback gain coefficient g and a time lag tau which meet a preset condition on a g-tau plane; based on the relation curve of g and tau and the mathematical model of the active suspension of the target vehicle, a stability partition map of the suspension system on the g-tau plane is obtained; constructing a target function; determining an optimization target based on the amplitude of the target function; and in combination with the stability partition map and the optimization target, obtaining an optimization value of tau. According to the invention, the vibration control effect of the suspension system can be optimized within the broadband of 4-12.5 Hz.

Description

Technical Field

[0001] The invention relates to the technical field of active vehicle suspension control, and in particular to a time-delay acceleration feedback control method for improving vehicle driving smoothness. Background Art

[0002] As an important part of the vehicle, the suspension system plays an important role in the smoothness, ride comfort and handling stability of the vehicle. Compared with the passive suspension, the active and semi-active suspension can adjust the control force in real time according to the driving conditions of the vehicle, which improves the driving characteristics of the vehicle to a certain extent. It is worth noting that in active and semi-active control systems, time lag is inevitable. Considering the influence of time lag factors in active and semi-active suspension has certain theoretical significance and application value.

[0003] At present, the research on time lag mainly focuses on two aspects: time lag compensation and time lag utilization. In terms of time lag compensation, some scholars have proposed time lag compensation methods such as the Smith prediction method and the adaptive linear quadratic Gaussian time lag compensation algorithm to improve or eliminate the adverse effects of time lag. In-depth research on time lag has found that if time lag is used reasonably, it can achieve the purposes of vibration absorption, vibration isolation and control of chaotic motion. Therefore, scholars have focused on the research of time lag utilization technology in vehicle suspension systems, and proposed time lag feedback control methods such as time lag state feedback, time lag displacement feedback and time lag velocity feedback to improve the driving smoothness of the vehicle. The existing technology has the following main problems in studying the vibration characteristics of vehicle active suspension:

[0004] 1. Acceleration sensors are widely used in vibration measurement and control systems due to their advantages of accurate measurement, simple structure, and light weight. For time-delay displacement, velocity, or state feedback control, the measured acceleration signal needs to be integrated, which leads to cumulative error problems.

[0005] 2. In the study of time-delay feedback control of vehicle suspension systems, constant time delay is mostly considered, and there is little discussion on variable time delay, which to a certain extent limits the flexibility of the time delay.

[0006] 3. When a vehicle is driving, the human body is most sensitive to vertical vibrations in the 4-12.5Hz frequency band. In the 4-8Hz frequency band, the human internal organs resonate; vibrations in the 8-12.5Hz frequency band have a greater impact on the human spinal system. Current research focuses on improving suspension performance through time-delay feedback control in the 4-8Hz frequency band, and rarely optimizes the vibration control effect of the suspension system in the wide frequency band of 4-12.5Hz. Summary of the invention

[0007] The purpose of the present invention is to provide a time-delay acceleration feedback control method for improving the ride smoothness of a vehicle. The time-delay acceleration feedback can bring about good vibration control effects in both constant time delay and variable time delay cases, providing flexibility for the value of the time delay.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] A time-delay acceleration feedback control method for improving vehicle driving comfort, comprising:

[0010] Based on the mechanical model of active suspension of target vehicle under time-delay acceleration feedback control and Newton's second law, a mathematical model of active suspension of target vehicle under time-delay acceleration feedback control is established.

[0011] Based on the mathematical model of the active suspension of the target vehicle, the harmonic balance method is used to obtain the sprung mass acceleration, suspension dynamic travel and tire dynamic load under simple harmonic road excitation;

[0012] Establishing a characteristic model of the suspension system, and based on the characteristic model, obtaining a relationship curve between g and τ that satisfies preset conditions on a g-τ plane, wherein g is a feedback gain coefficient and τ is a time lag;

[0013] Based on the relationship curve between g and τ and the mathematical model of the active suspension of the target vehicle, a stability partition diagram of the suspension system on the g-τ plane is obtained;

[0014] constructing an objective function based on the sprung mass acceleration, the suspension dynamic travel and the tire dynamic load;

[0015] Determining an optimization target based on the magnitude of the objective function;

[0016] The stability partition diagram and the optimization target are combined to obtain an optimized value of τ.

[0017] Optionally, the method for establishing a mathematical model of the active suspension of the target vehicle under time-delay acceleration feedback control includes:

[0018]

[0019] Where m1 is the sprung mass, k1 and c1 are the stiffness and damping coefficient of the suspension, m2 is the unsprung mass, k2 and c2 are the stiffness and damping coefficient of the tire, x1 and x2 are the vertical displacements of the sprung mass and the unsprung mass, respectively. d is the road surface excitation displacement, t is the time, represents the time-delay feedback control force, g is the feedback gain coefficient, τ is the time lag, is the vertical velocity of the sprung mass, is the vertical velocity of the unsprung mass, is the vertical acceleration of the sprung mass, is the vertical acceleration of the unsprung mass, To encourage speed for the road surface.

[0020] Optionally, obtaining the sprung mass, suspension dynamic travel, and tire dynamic load under simple harmonic road excitation includes:

[0021] According to the harmonic balance method, obtaining the form of a theoretical solution of the mathematical model;

[0022] Substituting the theoretical solution into the mathematical model of the active suspension of the target vehicle to obtain the coefficients in the theoretical solution;

[0023] Based on the coefficients, the sprung mass, the suspension dynamic stroke, and the tire dynamic load under simple harmonic road excitation are calculated.

[0024] Optionally, the acceleration of the sprung mass and the unsprung mass, the suspension dynamic travel and the tire dynamic load under simple harmonic road excitation are calculated as:

[0025] W i =G i sin(ωt+θ i )(i=1,3,4),

[0026]

[0027]

[0028] Wherein, W1 is the sprung mass acceleration, W3 is the suspension dynamic travel, W4 is the tire dynamic load, G1, G3, G4 are the amplitudes of W1, W3 and W4 respectively, θ1, θ3, θ4 are the phase angles of W1, W3 and W4 respectively, and a1, b1, a2 and b2 are coefficients.

[0029] Optionally, obtaining a relationship curve between g and τ that satisfies a preset condition on a g-τ plane includes:

[0030] Assume s=λi, and substitute it into the characteristic model, and obtain the first model and the second model respectively according to the real part and the imaginary part on the left side of the equal sign of the characteristic model being equal to 0, wherein λ represents the imaginary part of the characteristic root s, and i is the imaginary unit;

[0031] According to the first model and the second model, obtaining expressions of sin(λτ) and cos(λτ);

[0032] According to sin 2 (λτ)+cos 2 (λτ)=1, and the expression of feedback gain coefficient g is obtained;

[0033] According to the physical parameter values ​​of the suspension system, for the preset λ value, based on the expressions of sin(λτ) and cos(λτ) and the expression of the feedback gain coefficient g, several relationship curves between g and τ that satisfy the characteristic roots of the characteristic model as pure imaginary roots are obtained.

[0034] Optionally, obtaining a stability partition diagram of the suspension system on the g-τ plane includes:

[0035] The relationship curve between g and τ divides the g-τ plane into a number of closed areas, and a point is randomly selected in the closed area, and the coordinate value of the point and the physical parameters of the suspension system are substituted into the mathematical model to obtain an acceleration time history response curve;

[0036] The stability of the suspension system in the closed area is judged according to the acceleration time-history response curve, and a stability partition diagram of the suspension system on the g-τ plane is obtained.

[0037] Optionally, the objective function can be constructed as follows:

[0038]

[0039] Among them, W 10 , W 30 and W 40 They respectively represent the peak values ​​of the sprung mass acceleration, suspension dynamic travel, and tire dynamic load in the 4-12.5Hz frequency band when g=0kg. J is the objective function, α, β, and γ are all parameters, W1 is the sprung mass acceleration, W3 is the suspension dynamic travel, and W4 is the tire dynamic load.

[0040] Optionally, the optimization goal is: after applying time-delay acceleration feedback in a frequency band of 4-12.5 Hz, the amplitude of the objective function is smaller than the amplitude of the objective function under uncontrolled conditions.

[0041] Optionally, combining the stability partition map and the optimization target, obtaining an optimized value of τ includes:

[0042] Obtain a three-dimensional relationship diagram of Ω, g, and τ that meets the optimization goal, and obtain partitions of Ω and τ that meet the optimization goal according to a preset value of g;

[0043] The optimal value of τ is determined by combining the stability partition diagram and the partitions of Ω and τ.

[0044] The beneficial effects of the present invention are:

[0045] 1. Wide range of applications:

[0046] In view of the fact that acceleration sensors are widely used in vibration measurement and control systems, the time-delay feedback control force is in the form of time-delay acceleration feedback of the sprung mass. The use of time-delay acceleration feedback only requires the measured acceleration signal to be directly delayed and output, which not only fully utilizes the advantages of the acceleration sensor, but also effectively avoids the cumulative error problem caused by signal integration in displacement, velocity and state feedback. It can be seen that the application scope of time-delay acceleration feedback is wider.

[0047] 2. Flexible time delay value:

[0048] In the expression of the hysteresis feedback control force in the present invention, the value of the time lag τ can be a constant value or a variable value that changes with the change of Ω, so the value of the time lag is not limited to a constant value but can also be a variable value. Thus, flexibility is brought to the value of the time lag in the time-delay acceleration feedback.

[0049] 3. Good vibration control effect over a wide frequency band:

[0050] In the 4-12.5Hz frequency band, both constant-delay and variable-delay acceleration feedback can bring excellent vibration control effects. The peak values ​​of sprung mass acceleration, suspension dynamic travel and tire dynamic load are significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 The present invention is a flowchart of a time-delay acceleration feedback control method for improving vehicle driving smoothness according to an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0055] This embodiment provides a time-delay acceleration feedback control method for improving vehicle driving smoothness, including:

[0056] Based on the mechanical model of active suspension of target vehicle under time-delay acceleration feedback control and Newton's second law, a mathematical model of active suspension of target vehicle under time-delay acceleration feedback control is established.

[0057] In this embodiment, the mechanical model of the active suspension of the target vehicle refers to the mechanical model of the active suspension of a 1 / 4 vehicle.

[0058] Based on the mathematical model of active suspension of the target vehicle, the harmonic balance method is used to obtain the sprung mass acceleration, suspension dynamic travel and tire dynamic load under simple harmonic road excitation.

[0059] Establish a characteristic model of the suspension system, and based on the characteristic model, obtain a relationship curve between g and τ that meets preset conditions on the g-τ plane, where g is the feedback gain coefficient and τ is the time lag;

[0060] Based on the relationship curve between g and τ and the mathematical model of the active suspension of the target vehicle, the stability partition diagram of the suspension system on the g-τ plane is obtained;

[0061] Construct the objective function based on sprung mass acceleration, suspension dynamic travel and tire dynamic load;

[0062] Based on the magnitude of the objective function, the optimization target is determined;

[0063] Combine the stability partition map and the optimization objective to obtain the optimal value of τ.

[0064] Furthermore, the method for establishing a mathematical model of the active suspension of the target vehicle under time-delay acceleration feedback control includes:

[0065]

[0066] Where m1 is the sprung mass, k1 and c1 are the stiffness and damping coefficient of the suspension, m2 is the unsprung mass, k2 and c2 are the stiffness and damping coefficient of the tire, x1 and x2 are the vertical displacements of the sprung mass and the unsprung mass, respectively. d =rsin(ωt) is the road excitation displacement, t is time, r is the road excitation amplitude, ω=2πΩ, Ω is the road excitation frequency, represents the time-delay feedback control force, g is the feedback gain coefficient, τ is the time lag, is the vertical velocity of the sprung mass, is the vertical velocity of the unsprung mass, is the vertical acceleration of the sprung mass, is the vertical acceleration of the unsprung mass, To encourage speed for the road surface.

[0067] Furthermore, obtaining the acceleration of the sprung mass and the unsprung mass, the suspension dynamic travel and the tire dynamic load under the simple harmonic road excitation includes:

[0068] According to the harmonic balance method, the form of the theoretical solution of the mathematical model is obtained;

[0069] Substitute the theoretical solution into the mathematical model of the active suspension of the target vehicle to obtain the coefficients in the theoretical solution;

[0070] Based on the coefficients, the sprung mass, suspension travel and tire dynamic load under simple harmonic road excitation are calculated.

[0071] Furthermore, the sprung mass, suspension travel and tire dynamic load under simple harmonic road excitation are calculated as:

[0072] W i =G i sin(ωt+θ i )(i=1,3,4),

[0073]

[0074] Wherein, W1 is the sprung mass acceleration, W3 is the suspension dynamic travel, W4 is the tire dynamic load, G1, G3, G4 are the amplitudes of W1, W3 and W4 respectively, θ1, θ3, θ4 are the phase angles of W1, W3 and W4 respectively, and a1, b1, a2 and b2 are coefficients.

[0075] Furthermore, obtaining a relationship curve between g and τ that satisfies a preset condition on the g-τ plane includes:

[0076] Assume s = λi, and substitute it into the characteristic model. According to the fact that the real part and the imaginary part on the left side of the characteristic model are equal to 0, the first model and the second model are obtained respectively, where λ represents the imaginary part of the characteristic root s;

[0077] According to the first model and the second model, expressions of sin(λτ) and cos(λτ) are obtained;

[0078] According to sin 2 (λτ)+cos 2 (λτ)=1, and the expression of feedback gain coefficient g is obtained;

[0079] According to the physical parameter values ​​of the suspension system, for the preset λ value, based on the expressions of sin(λτ) and cos(λτ) and the expression of the feedback gain coefficient g, several relationship curves between g and τ that satisfy the characteristic model and whose characteristic roots are pure imaginary roots are obtained.

[0080] Furthermore, obtaining the stability partition diagram of the suspension system on the g-τ plane includes:

[0081] The relationship curve between g and τ divides the g-τ plane into several closed areas. Select any point in the closed area, substitute the coordinate value of the point and the physical parameters of the suspension system into the mathematical model, and obtain the acceleration time history response curve;

[0082] According to the acceleration time-history response curve, the stability of the suspension system in the closed area is judged, and the stability partition diagram of the suspension system on the g-τ plane is obtained.

[0083] Furthermore, the method of constructing the objective function is:

[0084]

[0085] Among them, W 10 , W 30 and W 40 They represent the acceleration of the sprung mass, the suspension dynamic travel, and the peak value of the tire dynamic load in the 4-12.5Hz frequency band when g=0kg. J is the objective function, and α, β, and γ are all parameters.

[0086] Furthermore, the optimization goal is that the amplitude of the objective function after applying the delayed acceleration feedback in the 4-12.5 Hz frequency band is smaller than the amplitude of the objective function under the uncontrolled condition.

[0087] Furthermore, combining the stability partition diagram and the optimization goal, the optimal value of τ is obtained including:

[0088] Obtain a three-dimensional relationship diagram of Ω, g, and τ that meets the optimization goal, and obtain the partitions of Ω and τ that meet the optimization goal according to the preset value of g;

[0089] Combining the stability partition diagram, the partitions of Ω and τ, the optimal value of τ is determined.

[0090] The invention will be further described below in conjunction with the accompanying drawings. Figure 1 The specific steps shown include:

[0091] 1. Establish a mathematical model of the 1 / 4 vehicle active suspension under time-delay acceleration feedback control: Establishing the mathematical model of the suspension system provides a theoretical basis for the stability analysis of the suspension system and the optimization of the time delay.

[0092] Based on the mechanical model of 1 / 4 vehicle active suspension under time-delay acceleration feedback control and Newton's second law, the mathematical model of 1 / 4 vehicle active suspension under time-delay acceleration feedback control is established. The harmonic balance method is used to determine the analytical expressions of the acceleration of sprung and unsprung masses, suspension dynamic travel, and tire dynamic load under simple harmonic road excitation.

[0093] Specifically, step 1: establishing a dynamic model of a quarter vehicle active suspension under time-delay acceleration feedback control includes:

[0094] (a) Mathematical modeling: Acceleration sensors are widely used in vibration measurement and control systems. This mathematical model constructs a time-delay feedback control force based on the acceleration signal of the sprung mass, which can not only give full play to the advantages of the acceleration sensor, but also effectively avoid the cumulative error problem caused by signal integration in displacement, velocity and state feedback control.

[0095] Based on the mechanical model of 1 / 4 vehicle active suspension under time-delay acceleration feedback control, the mathematical model of the system is established according to Newton's second law as follows:

[0096]

[0097] Where m1 is the sprung mass, k1 and c1 are the stiffness and damping coefficient of the suspension, m2 is the unsprung mass, k2 and c2 are the stiffness and damping coefficient of the tire, x1 and x2 are the vertical displacements of the sprung mass and the unsprung mass, and x is the road excitation displacement. d =rsin(ωt), where t represents time, r represents the road excitation amplitude, ω=2πΩ, Ω represents the road excitation frequency in Hz. represents the time-delay feedback control force, g is the feedback gain coefficient, τ is the time lag, is the vertical velocity of the sprung mass, is the vertical velocity of the unsprung mass, is the vertical acceleration of the sprung mass, is the vertical acceleration of the unsprung mass, is the road excitation speed. In this model, the time lag τ and the feedback gain coefficient g are used as control parameters, and their values ​​determine the stability and vibration control effect of the suspension system.

[0098] (b) Theoretical solution of system response:

[0099] According to the harmonic balance method, the theoretical solutions of equations (1) and (2) have the following form:

[0100] x1=a1sin(ωt)+b1cos(ωt) (3)

[0101] x2=a2sin(ωt)+b2cos(ωt) (4)

[0102] Where a1, b1, a2 and b2 are coefficients in the theoretical solution.

[0103] Substituting equations (3) and (4) into equations (1) and (2), we can obtain the expressions for a1, b1, a2, and b2 based on the equality of the coefficients of sin(ωt) and cos(ωt) on both sides of the equation:

[0104]

[0105] The theoretical expressions of sprung mass acceleration W1, unsprung mass acceleration W2, suspension dynamic travel W3 and tire dynamic load W4 under simple harmonic road excitation are as follows:

[0106] W i =G i sin(ωt+θ i ) (i=1,2,3,4) (6)

[0107] in

[0108]

[0109] G1, G2, G3, G4 are the amplitudes of W1, W2, W3 and W4 respectively; θ1, θ2, θ3 and θ4 are the phase angles of W1, W2, W3 and W4 respectively. The unsprung mass acceleration W2 here reflects the completeness of the above formula.

[0110] 2. Use semi-analytical and semi-numerical methods to analyze the stability of the suspension system

[0111] The stability of the suspension system is the premise for its normal operation. By analyzing the stability of the suspension system, the range of g and τ that ensures the stability of the suspension system can be determined.

[0112] Firstly, based on the characteristic equation of the system, namely the characteristic model, the analytical expressions of the time lag and feedback gain coefficients satisfying the requirement that the characteristic roots are pure imaginary roots are determined.

[0113] Secondly, on the two-parameter plane of time lag and feedback gain coefficient, several relationship curves between time lag and feedback gain coefficient satisfying the characteristic root being a pure imaginary root are drawn. These relationship curves divide the two-parameter plane into several closed areas.

[0114] Again, select a point in any closed area. Substitute the coordinate value of the point, the physical parameters of the suspension, and the road excitation parameters into the mathematical model of the suspension system for numerical calculation to obtain the time history curve of the sprung mass acceleration response. If the curve diverges, it means that the suspension system is unstable in the closed area where the point is located; if the curve converges, it means that the suspension system is stable in the closed area where the point is located.

[0115] In this way, the stability of the suspension system in each closed area can be determined, and finally the stability partition diagram of the suspension system on the two-parameter plane of time lag and feedback gain coefficient can be obtained.

[0116] Specifically, step 2: system stability analysis includes:

[0117] (a) Establish the characteristic equation (characteristic model) of the system:

[0118]

[0119] Where s represents the characteristic root of the characteristic equation.

[0120] (b) Determine the time lag and feedback gain coefficient values ​​that satisfy the requirement that the characteristic root is a pure imaginary root:

[0121] Assume s = λi, λ represents the imaginary part of the characteristic root s, i is the imaginary unit, substitute s = λi into the characteristic equation (7), and the real and imaginary parts on the left side of the equation are equal to 0 respectively, so we get:

[0122] -c2gλ 3 sin(λτ)+gλ 2 (m2λ 2 -k2)cos(λτ)+m1m2λ 4 +(-c1c2-k1m1-k2m1-k1m2)λ 2 +k1k2=0(8)

[0123] g 2 (k2-m2λ 2 )sin(λτ)-c2gλ 3 cos(λτ)+(c2k1+c1k2)λ-(c1m1+c2m1+c1m2)λ 3 =0(9)

[0124] Solving equations (8) and (9) simultaneously, we obtain the expressions for sin(λτ) and cos(λτ):

[0125]

[0126] By sin 2 (λτ)+cos 2 (λτ)=1, the expression of feedback gain coefficient g can be obtained:

[0127]

[0128] When the physical parameters of the given suspension system are: m1 = 136.05kg, m2 = 24.288kg, k1 = 10200N / m, k2 = 98000N / m, c1 = 15N·s / m, c2 = 153N·s / m. For any value of λ, the corresponding feedback gain coefficient g and time lag τ are obtained according to equations (10)-(12). Let λ be taken in the interval of 0.1 in the range of 0.01 to 500, and obtain several relationship curves between g and τ on the two parameter planes of g and τ, whose characteristic roots satisfy the characteristic equation (7) as pure imaginary roots.

[0129] (c) Draw the stability partition diagram of the system:

[0130] The relationship curve between g and τ divides the g-τ plane into several closed areas. To determine the stability of the system in each closed area, select a point in each closed area. Substitute the coordinate value of the point, r = 0.004m, ω = 4πrad / s, and the physical parameters of the system m1, m2, c1, c2, k1, k2 into equations (1) and (2) for numerical calculation to obtain the acceleration time-history response curve of the system. If the curve diverges, it means that the system is unstable in the closed area where the point is located; if the curve converges, it means that the system is stable in the closed area where the point is located. In this way, the stability of the suspension system in each closed area can be determined, and finally the stability partition diagram of the system on the g-τ plane, that is, the result of the stability analysis, is obtained.

[0131] 3. Optimization of time delay:

[0132] Sprung mass acceleration, suspension dynamic travel and tire dynamic load are important indicators for evaluating the performance of the suspension system, which directly affect the smoothness of vehicle driving.

[0133] Taking into account the acceleration of sprung mass, suspension travel and tire dynamic load, the weighted value of the above three indicators is used as the objective function. The optimization goal is: the amplitude of the objective function is reduced compared with the uncontrolled case after applying delayed acceleration feedback in the 4-12.5Hz frequency band. When the feedback gain coefficient takes a certain value, a partition diagram of the excitation frequency and time lag that achieves the optimization goal is drawn. Combined with the partition diagram and the stability analysis results, the optimal value of the time lag is obtained.

[0134] Specifically, the optimal value of the time delay in the 4-12.5 Hz frequency band obtained in step 3 includes:

[0135] Taking into account the sprung mass acceleration, suspension dynamic travel and tire dynamic load, the weighted value of the above three indicators is used as the objective function. The expression of the objective function J is as follows:

[0136]

[0137] Where W 10 , W 30 and W 40 They represent the acceleration of the sprung mass, the suspension dynamic travel, and the peak value of the tire dynamic load in the 4-12.5 Hz frequency band when g=0 kg. In this embodiment, W 10 =2.69m / s 2 , W 30 =0.036m, W 40 = 3413.53 N. In addition, α = 0.6, β = γ = 0.2.

[0138] (a) Define J1 as the magnitude of the objective function J, It indicates the percentage of J1 reduction after applying the time-delay acceleration feedback control. The optimization target is determined as: D0>0 in the 4-12.5Hz frequency band.

[0139] (b) Draw a three-dimensional relationship diagram of the excitation frequency Ω, feedback gain coefficient g and time lag τ that satisfies D0>0 in the frequency band of 4-12.5 Hz.

[0140] (c) In this three-dimensional relationship diagram, the feedback gain coefficient is taken as 80kg, and the partition of the excitation frequency Ω and the time lag τ that satisfies D0>0 is obtained.

[0141] (d) Combining the stability analysis results and the partitioning of the excitation frequency Ω and the time lag τ in (c), it is determined that both the constant time lag τ = 0.02s and the variable time lag τ = (0.252-0.013Ω)s satisfy D0>0.

[0142] (e) Comparative analysis of the changes in the amplitude of the objective function, sprung mass acceleration, suspension dynamic travel and tire dynamic load under no control, constant time-delay and variable time-delay acceleration feedback control shows that: within the 4-12.5 Hz frequency band, compared with the no control case, the amplitude of the objective function and the amplitude of the sprung mass acceleration under constant time-delay and variable time-delay acceleration feedback control are significantly reduced; the reduction in suspension dynamic deflection and peak road tire dynamic load under constant time-delay and variable time-delay acceleration feedback control is basically the same, at 22% and 21% respectively.

[0143] The technical solution of this embodiment can solve the following technical problems:

[0144] 1. Introduce time-delay acceleration feedback control in the passive vehicle suspension system. In the controller, the collected acceleration signal is directly delayed and output to the actuator, which effectively avoids the cumulative error problem caused by signal integration in displacement, velocity and state feedback.

[0145] 2. Considering that the human body's sensitive frequency band to vertical vibration is 4-12.5 Hz, an optimized value of the time lag within the 4-12.5 Hz frequency band is proposed, which reduces the acceleration amplitude of the sprung mass, the dynamic travel of the suspension and the peak dynamic load of the tire.

[0146] 3. It is verified that time-delay acceleration feedback can bring good vibration control effects in both constant time delay and variable time delay cases, providing flexibility for the value of time delay.

[0147] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A time-delay acceleration feedback control method for improving vehicle driving comfort, characterized in that: include: Based on the mechanical model of active suspension of target vehicle under time-delay acceleration feedback control and Newton's second law, a mathematical model of active suspension of target vehicle under time-delay acceleration feedback control is established. Based on the mathematical model of the active suspension of the target vehicle, the harmonic balance method is used to obtain the sprung mass acceleration, suspension dynamic travel and tire dynamic load under simple harmonic road excitation; Establishing a characteristic model of the suspension system, and based on the characteristic model, obtaining a relationship curve between g and τ that satisfies preset conditions on a g-τ plane, wherein g is a feedback gain coefficient and τ is a time lag; Based on the relationship curve between g and τ and the mathematical model of the active suspension of the target vehicle, a stability partition diagram of the suspension system on the g-τ plane is obtained; constructing an objective function based on the sprung mass acceleration, the suspension dynamic travel and the tire dynamic load; Determining an optimization target based on the magnitude of the objective function; The stability partition diagram and the optimization target are combined to obtain an optimized value of τ.

2. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: The method of establishing the mathematical model of the active suspension of the target vehicle under the time-delay acceleration feedback control includes: Where m1 is the sprung mass, k1 and c1 are the stiffness and damping coefficient of the suspension, m2 is the unsprung mass, k2 and c2 are the stiffness and damping coefficient of the tire, x1 and x2 are the vertical displacements of the sprung mass and the unsprung mass, respectively. d is the road surface excitation displacement, t is the time, represents the time-delay feedback control force, g is the feedback gain coefficient, τ is the time lag, is the vertical velocity of the sprung mass, is the vertical velocity of the unsprung mass, is the vertical acceleration of the sprung mass, is the vertical acceleration of the unsprung mass, To encourage speed for the road surface.

3. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 2, characterized in that: Obtaining the sprung mass, suspension travel, and tire dynamic load under simple harmonic road excitation includes: According to the harmonic balance method, obtaining the form of a theoretical solution of the mathematical model; Substituting the theoretical solution into the mathematical model of the active suspension of the target vehicle to obtain the coefficients in the theoretical solution; Based on the coefficients, the sprung mass, the suspension dynamic stroke, and the tire dynamic load under simple harmonic road excitation are calculated.

4. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 3, characterized in that: The acceleration of the sprung mass and the unsprung mass, the suspension dynamic travel and the tire dynamic load under simple harmonic road excitation are calculated as: W i =G i sin(ωt+θ i (i=1,3,4), Wherein, W1 is the sprung mass acceleration, W3 is the suspension dynamic travel, W4 is the tire dynamic load, G1, G3, G4 are the amplitudes of W1, W3 and W4 respectively, θ1, θ3, θ4 are the phase angles of W1, W3 and W4 respectively, and a1, b1, a2 and b2 are coefficients.

5. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: Obtaining a relationship curve between g and τ that satisfies preset conditions on the g-τ plane includes: Assume s=λi, and substitute it into the characteristic model, and obtain the first model and the second model respectively according to the real part and the imaginary part on the left side of the equal sign of the characteristic model being equal to 0, wherein λ represents the imaginary part of the characteristic root s, and i is the imaginary unit; According to the first model and the second model, obtaining expressions of sin(λτ) and cos(λτ); According to sin 2 (λτ)+cos 2 (λτ)=1, and the expression of feedback gain coefficient g is obtained; According to the physical parameter values ​​of the suspension system, for the preset λ value, based on the expressions of sin(λτ) and cos(λτ) and the expression of the feedback gain coefficient g, several relationship curves between g and τ that satisfy the characteristic roots of the characteristic model as pure imaginary roots are obtained.

6. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: Obtaining the stability partition diagram of the suspension system on the g-τ plane includes: The relationship curve between g and τ divides the g-τ plane into a number of closed areas, and a point is randomly selected in the closed area, and the coordinate value of the point and the physical parameters of the suspension system are substituted into the mathematical model to obtain an acceleration time history response curve; The stability of the suspension system in the closed area is judged according to the acceleration time-history response curve, and a stability partition diagram of the suspension system on the g-τ plane is obtained.

7. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: The method to construct the objective function is: Among them, W 10 , W 30 and W 40 They respectively represent the peak values ​​of the sprung mass acceleration, suspension dynamic travel, and tire dynamic load in the 4-12.5Hz frequency band when g=0kg. J is the objective function, α, β, and γ are all parameters, W1 is the sprung mass acceleration, W3 is the suspension dynamic travel, and W4 is the tire dynamic load.

8. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: The optimization goal is that the amplitude of the objective function after applying the time-delay acceleration feedback in the 4-12.5 Hz frequency band is smaller than the amplitude of the objective function under the uncontrolled condition.

9. The time-delay acceleration feedback control method for improving vehicle driving comfort according to claim 1, characterized in that: Combining the stability partition map and the optimization target, obtaining the optimal value of τ includes: Obtain a three-dimensional relationship diagram of Ω, g, and τ that meets the optimization goal, and obtain partitions of Ω and τ that meet the optimization goal according to a preset value of g; The optimal value of τ is determined by combining the stability partition diagram and the partitions of Ω and τ.

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