Automobile brake stability control method and system considering random parameters and automobile

Abstract

The invention relates to an automobile braking stability control method considering random parameters, a system thereof and an automobile in the technical field of automobile braking. The method comprises the steps that when an automobile is braked and the frequency ratio of automobile braking angular velocity response is larger than or equal to a calibrated threshold value, target braking pressure FN0 is calculated according to the wheel angular velocity omega0 at the initial time of automobile braking, and the target braking pressure FN0 is output to a brake block through a braking pressure regulator. C is torsional damping of the brake disc, D is Gaussian white noise, kappa 1 is 1.5 (mu s-mu m) / vm, kappa 3 is 0.5 (mu s-mu m) / vm < 3 >, mu s, mu m, vm and k are static friction coefficient, sliding friction coefficient, sliding angular velocity and torsional rigidity of the brake disc respectively, rho1 is random control parameter of k, and R is equivalent action radius of a brake block acting on the brake disc. According to the method, the technical problem that the automobile brake chatter control effect is poor due to the fact that the brake chatter stability boundary is difficult to obtain due to the fact that the brake disc rigidity parameter has remarkable uncertainty is solved, and effective suppression of automobile brake chatter is achieved.

Description

Technical Field

[0001] This invention relates to a vehicle braking stability control method in the field of automotive braking technology, and particularly to a vehicle braking stability control method considering random parameters, a vehicle braking control method employing the aforementioned vehicle braking stability control method, a vehicle braking stability control system considering random parameters, a vehicle braking control system equipped with the aforementioned vehicle braking stability control system, and a vehicle. Background Technology

[0002] Brake shudder is a harmful nonlinear vibration phenomenon, typically manifesting as small-amplitude, low-frequency shaking during braking. This vibration can be transmitted to the brake pedal, steering wheel, and vehicle body, reducing ride comfort. Furthermore, brake shudder causes fluctuations in braking torque, severely impacting braking safety. Existing technologies are primarily limited to deterministic theoretical frameworks, identifying brake shudder occurrence by collecting wheel-related vibration signals and calculating the desired braking pressure to suppress the phenomenon. However, due to uneven brake disc material distribution, wear, and corrosion, significant uncertainties exist in brake disc stiffness parameters, making it difficult to accurately obtain the brake shudder stability boundary and resulting in poor brake shudder control.

[0003] For example, ZL202011615043.2, "A Method and Device for Suppressing Brake Flutter Based on Operating Conditions," utilizes an accelerometer to detect the vehicle's braking vibration state. The control unit calculates the friction coefficient at the current sampling point to determine the friction force change function, predicting the braking force change value based on this, and thus suppressing brake flutter by adjusting the brake fluid state. Another example is ZL201110407289.5, "A Control System and Method for Braking Vibration Reduction in Four-Wheel Wheel-Side Drive Electric Vehicles," which identifies braking torque fluctuation signals through brake pressure and pedal displacement signals. It controls the motor output to reduce the motor torque that reduces braking force fluctuations, thereby suppressing vehicle vibration caused by braking flutter. Yet another example is ZL202211340883.1, "An Electric Wheel Braking Flutter Prediction Control System and Method," which acquires the desired braking force signal, wheel angular velocity signal, and wheel hub motor angular velocity signal to predict flutter. It combines this with a stability curve to calculate the wheel cylinder braking pressure to suppress flutter and compensates for insufficient braking torque through motor torque. Summary of the Invention

[0004] To address the problem that traditional technologies suffer from poor brake flutter control due to the significant uncertainty in brake disc stiffness parameters, making it difficult to obtain brake flutter stability boundaries, this invention discloses a vehicle brake stability control method considering random parameters, a vehicle brake control method employing the aforementioned method, a vehicle brake stability control system considering random parameters, a vehicle brake control system equipped with the aforementioned vehicle brake stability control system, and a vehicle.

[0005] This invention is achieved using the following technical solution:

[0006] A vehicle braking stability control method considering random parameters includes the following steps:

[0007] When a car brakes, and λ≥λ0, the target braking pressure F is calculated based on the wheel angular velocity ω0 at the initial moment of braking. N0 ;

[0008] Adjust the brake pressure output from the brake pressure regulator to the brake pads to F. N0 ;

[0009] Wherein, λ is the frequency ratio of the vehicle's braking angular velocity response;

[0010] λ0 is the calibrated threshold;

[0011] c is the torsional damping of the brake disc, D is Gaussian white noise, and κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ s μ m v m ρ1 and k are the static friction coefficient, sliding friction coefficient, sliding angular velocity, and torsional stiffness of the brake disc, respectively. ρ1 is a random control parameter of k, and R is the equivalent radius of action of the brake block on the brake disc.

[0012] As a further improvement to the above scheme, when λ < λ0, vehicle braking stability control is not required during vehicle braking.

[0013] As a further improvement to the above scheme, λ is: Among them, f s It is the dominant frequency of the brake disc's angular velocity response, f. t It is the calibrated frequency of vehicle braking vibration.

[0014] As a further improvement to the above scheme, FN0 The design methodology includes the following steps:

[0015] Establish a system that includes ω0 and the braking pressure F on the brake disc at the initial moment of braking. N A single-degree-of-freedom dynamic model of the transmission system torque T:

[0016]

[0017] In the formula, θ, These are the brake disc's rotation angle, angular velocity, and acceleration, respectively; I is the brake disc's moment of inertia; F μ It is the braking friction force on the brake disc, based on the Stribeck friction effect, and its polynomial expression is as follows.

[0018]

[0019] In the formula, It is the angular velocity of the brake disc relative to the brake pads, sgn(v r ) is a sign function;

[0020] To solve for the steady-state solution of the vehicle braking system, let Substituting into equation (1), and combining equations (1) and (2), we obtain the steady-state solution of the vehicle braking system as follows: Introducing a new state variable φ=θ-θ0, and substituting θ=φ+θ0 into equations (1) to (2), while using 2D Gaussian white noise ξ(t) to represent the uncertainty of the brake disc torsional stiffness, the equivalent stochastic dynamic model of vehicle brake flutter is obtained as follows:

[0021]

[0022] Let q = φ, Transform equation (3) into

[0023]

[0024] In the formula, It is the system Hamiltonian function, m 11 =c 11 +c 12 p+c 13 p 2 , B(t) is a standard Weiner process;

[0025] Based on the stochastic averaging method, equation (4) is transformed into a one-dimensional Iton stochastic differential equation.

[0026] dH=m(H)dt+σ(H)dB(t) (17)

[0027] In the formula, m(H) is the drift coefficient, and σ(H) is the diffusion coefficient. The specific expression is as follows:

[0028]

[0029] In the formula, O(H) is a first-order infinitesimal with respect to H. 2 ) is a second-order infinitesimal with respect to H;

[0030] Based on the behavior analysis of the singular boundaries of the stochastic differential equations, the stochastic stability condition of the system for achieving vehicle braking stability control is as follows: The stability boundary of the vehicle braking pressure is F. N0 .

[0031] The present invention also provides a vehicle braking stability control system that considers random parameters, comprising:

[0032] An angular velocity sensor is used to collect the wheel angular velocity ω0 at the initial stage of vehicle braking.

[0033] The electronic control unit, used during vehicle braking, calculates the target braking pressure F based on the wheel angular velocity ω0 at the initial moment of braking, provided that λ≥λ0. N0 And adjust the braking pressure output from the brake pressure regulator to the brake pads to F. N0 ;

[0034] Wherein, λ is the frequency ratio of the vehicle's braking angular velocity response;

[0035] λ0 is the calibrated threshold;

[0036] c is the torsional damping of the brake disc, D is Gaussian white noise, and κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ s μ m v m ρ1 and k are the static friction coefficient, sliding friction coefficient, sliding angular velocity, and torsional stiffness of the brake disc, respectively. ρ1 is a random control parameter of k, and R is the equivalent radius of action of the brake block on the brake disc.

[0037] As a further improvement to the above scheme, λ is: Among them, f s It is the dominant frequency of the brake disc's angular velocity response, f. t It is the calibrated frequency of vehicle braking vibration.

[0038] As a further improvement to the above solution, the vehicle braking stability control system also includes F N0 Design system, F N0 The design system includes:

[0039] The angular velocity sensor;

[0040] A brake pressure sensor is used to collect the brake pressure F of the brake disc at the initial stage of vehicle braking. N ;

[0041] A torque sensor is used to collect the torque T of the brake disc when the car is initially braking.

[0042] Designer, used according to F N T design F N0 F N0 The design methodology includes the following steps:

[0043] Establish a system containing ω0 and F N Single-degree-of-freedom dynamic model of T:

[0044]

[0045] In the formula, θ, These are the brake disc's rotation angle, angular velocity, and acceleration, respectively; I is the brake disc's moment of inertia; F μ It is the braking friction force on the brake disc, based on the Stribeck friction effect, and its polynomial expression is as follows.

[0046]

[0047] In the formula, It is the angular velocity of the brake disc relative to the brake pads, sgn(v r ) is a sign function;

[0048] To solve for the steady-state solution of the vehicle braking system, let Substituting into equation (1), and combining equations (1) and (2), we obtain the steady-state solution of the vehicle braking system as follows: Introducing a new state variable φ=θ-θ0, and substituting θ=φ+θ0 into equations (1) to (2), while using 2D Gaussian white noise ξ(t) to represent the uncertainty of the brake disc torsional stiffness, the equivalent stochastic dynamic model of vehicle brake flutter is obtained as follows:

[0049]

[0050] Let q = φ, Transform equation (3) into

[0051]

[0052] In the formula, It is the system Hamiltonian function, m 11 =c 11 +c 12 p+c 13 p 2 , B(t) is a standard Weiner process;

[0053] Based on the stochastic averaging method, equation (4) is transformed into a one-dimensional Iton stochastic differential equation.

[0054] dH=m(H)dt+σ(H)dB(t) (23)

[0055] In the formula, m(H) is the drift coefficient, and σ(H) is the diffusion coefficient. The specific expression is as follows:

[0056]

[0057] In the formula, O(H) is a first-order infinitesimal with respect to H. 2 ) is a second-order infinitesimal with respect to H;

[0058] Based on the behavior analysis of the singular boundaries of the stochastic differential equations, the stochastic stability condition of the system for achieving vehicle braking stability control is as follows: The stability boundary of the vehicle braking pressure is F. N0 .

[0059] The present invention also provides a vehicle braking control method, which, when the vehicle is braking, adopts the above-mentioned vehicle braking stability control method that arbitrarily considers random parameters, adjusts the braking pressure output by the brake pressure regulator to the brake pads, and realizes braking control of the vehicle's brake disc.

[0060] The present invention also provides an automotive braking control system, comprising: a brake pressure regulator for adjusting the brake pressure on the brake pads; and an automotive braking stability control system for controlling any of the above-mentioned random parameters of the brake pressure regulator.

[0061] The present invention also provides a car equipped with the above-mentioned car braking control system for achieving random stability control of the car during braking.

[0062] Compared with the prior art, the advantages of the present invention are as follows:

[0063] (1) This invention constructs a stochastic dynamic model of vehicle braking flutter based on the Stribeck friction effect, studies the stochastic bifurcation characteristics of vehicle braking, obtains the stochastic instability conditions and boundaries of vehicle braking flutter, and designs a vehicle braking stability control method based on this, which is extremely important for improving vehicle braking stability.

[0064] (2) This invention establishes a stochastic dynamic model of vehicle brake flutter, obtains the Iton stochastic differential process and its drift coefficient and diffusion coefficient, solves the stochastic stability boundary of vehicle braking pressure under different driving conditions, and solves the technical problem of poor vehicle brake flutter control effect due to the significant uncertainty of brake disc stiffness parameters in traditional technology.

[0065] The core advantage of the method described in this invention is that:

[0066] (1) Construct a dynamic model of vehicle braking flutter, collect the wheel angular velocity, braking pressure on the brake disc, and transmission torque signal on the brake disc during vehicle braking, and establish an equivalent stochastic dynamic model of vehicle braking flutter considering stiffness uncertainty.

[0067] (2) The random stability boundary of vehicle braking pressure is determined by the random averaging method, the target braking pressure is solved in real time, and the vehicle braking vibration is suppressed by adjusting the wheel braking force, so as to provide technical support for better improving vehicle braking performance. Attached Figure Description

[0068] Figure 1 This is a flowchart of the automobile braking control method provided in Embodiment 1 of the present invention.

[0069] Figure 2 for Figure 1 The design principle diagram of the target braking pressure model used in the Chinese automotive braking control method.

[0070] Figure 3 This is a schematic diagram illustrating the working principle of an automotive braking control system provided in Embodiment 2 of the present invention.

[0071] Figure 4 for Figure 3 After adopting the vehicle braking stability control method, the random stability boundary of braking pressure at different wheel speeds is determined in the Chinese automotive braking control system.

[0072] Figure 5 for Figure 3 The response time history of the vehicle braking system under different braking pressures after the vehicle braking control system adopts the vehicle braking stability control method. Detailed Implementation

[0073] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0074] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0075] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0076] Please see Figure 1 This is a flowchart of an automotive braking control method provided in Embodiment 1 of the present invention. The automotive braking control method is mainly used in automobiles to control the brake discs. In this embodiment, the automotive braking control method is used to: during vehicle braking, employ an automotive braking stability control method that considers random parameters to adjust the braking pressure output from the brake pressure regulator to the brake pads, thereby achieving braking control of the vehicle's brake discs. Therefore, the automotive braking control method includes the steps of: vehicle braking, while simultaneously employing an automotive braking stability control method that considers random parameters.

[0077] The vehicle braking stability control method includes the following steps:

[0078] When a car brakes, calculate the frequency ratio λ of the car's braking angular velocity response;

[0079] Determine whether λ≥λ0 holds true;

[0080] When λ≥λ0, the target braking pressure F is calculated based on the wheel angular velocity ω0 at the initial braking point of the vehicle. N0 ;

[0081] Adjust the brake pressure output from the brake pressure regulator to the brake pads to F. N0 ;

[0082] When λ < λ0, vehicle braking stability control is not required during vehicle braking.

[0083] There are many methods for calculating λ. In this embodiment, a relatively common method is introduced. The angular velocity ω0 of the car's brake disc at the initial moment of braking is collected. Noise signals can be removed from ω0 using a filter. Then, the power spectrum of the brake disc's angular velocity ω0 is solved. Based on this, the frequency ratio λ of the car's braking angular velocity response is calculated as follows: Among them, f s It is the dominant frequency of the brake disc's angular velocity response, f. t This is the calibrated frequency of vehicle brake shudder. A pre-calibrated threshold λ0 is used as the brake shudder identification condition; that is, when λ≥λ0, vehicle braking will result in brake shudder. Therefore, vehicle brake stability control methods can be used to control vehicle brake stability: adjusting the brake pressure output from the brake pressure regulator to the brake pads to F. N0 This helps to suppress brake vibration and improve vehicle braking stability.

[0084] In other embodiments, when the vehicle brakes, the steps of calculating the frequency ratio λ of the vehicle's braking angular velocity response and determining whether λ≥λ0 holds true can be placed before the vehicle braking stability control method. Only when λ≥λ0 holds true will the vehicle braking control method call the vehicle braking stability control method that considers random parameters.

[0085] Target braking pressure F N0 The calculation of this is an innovative design element in this invention. Target braking pressure F N0 It can be calculated using the designed target braking pressure model:

[0086]

[0087] In the formula, c is the torsional damping of the brake disc, D is Gaussian white noise, and κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ s μ m v m ρ1 and k are the static friction coefficient, sliding friction coefficient, sliding angular velocity, and torsional stiffness of the brake disc, respectively. ρ1 is a random control parameter of k, and R is the equivalent radius of action of the brake block on the brake disc.

[0088] In other words, when invoking the vehicle braking stability control method, the target braking pressure F can be calculated using the target braking pressure model based solely on the wheel angular velocity ω0. N0 This invention establishes a stochastic dynamic model of vehicle braking flutter, obtains the Iton stochastic differential process and its drift and diffusion coefficients, solves the stochastic stability boundary of vehicle braking pressure under different driving conditions, and effectively suppresses vehicle braking flutter by adjusting the vehicle braking force.

[0089] The design of the target braking pressure model can be achieved through an F N0 Design system implementation. For example... Figure 2 As shown, F N0 The design system may include: torque sensor 12, brake pressure sensor 13, angular velocity sensor 14, and designer 10. N0 The system design needs to be based on the vehicle's braking control system. The vehicle includes the brake disc 3 and the braking control system for the brake disc 3.

[0090] Figure 2 The vehicle's braking control system includes a pair of brake pads 5, a float caliper 6, a piston 7, and a brake pressure regulator 8. The brake pressure regulator 8 applies braking pressure to the brake pads 5 by driving the piston 7, which, through the float caliper 6, causes the pair of brake pads 5 to clamp the brake disc 3, thereby braking the brake disc 3. Adjusting the braking pressure output by the brake pressure regulator 8 changes the rotational speed of the brake disc 3, thus altering the braking distance and braking speed of the vehicle during braking.

[0091] Torque sensor 12 is used to collect the transmission torque T on the brake disc 3 at the initial stage of vehicle braking; pressure sensor 13 is used to collect the braking pressure F on the brake pad 5 at the initial stage of vehicle braking. N Angular velocity sensor 14 is used to collect the wheel angular velocity ω0 at the initial stage of vehicle braking. Designer 10 is used to design the target braking pressure model according to the design method of the target braking pressure model. In this embodiment, based on F... N 、T、ω0 design F N0 The design method of the target braking pressure model will be described in detail next to demonstrate its feasibility.

[0092] The design method of the target braking pressure model, namely F N0 The design method mainly includes the following steps: modeling vehicle braking flutter considering stiffness uncertainty, and solving the target braking pressure under random parameter excitation.

[0093] 1. Modeling of vehicle braking chatter considering uncertain stiffness

[0094] Establish a system that includes the wheel angular velocity ω0 during vehicle braking and the braking pressure F on the brake disc.N A single-degree-of-freedom dynamic model of the transmission system torque T:

[0095]

[0096] In the formula, θ, These are the brake disc's rotation angle, angular velocity, and acceleration, respectively; I is the brake disc's moment of inertia; c is the brake disc's torsional damping; k is the brake disc's torsional stiffness; R is the equivalent radius of action of the brake pads on the brake disc; T is the transmission torque acting on the brake disc during braking; F μ It is the braking friction force on the brake disc, based on the Stribeck friction effect, and its polynomial expression is as follows.

[0097]

[0098] In the formula, μ s κ1 is the static friction coefficient of the brake disc; κ1 and κ3 are both intermediate variables, and their formulas are as follows: κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ m It is the coefficient of sliding friction of the brake disc, v m It is the angular velocity of the brake disc; F N It is braking pressure; ω is the angular velocity of the brake disc relative to the brake pads, and ω0 is the initial angular velocity of the wheel during braking; sgn(v r ) is a symbolic function.

[0099] To solve for the steady-state solution of the vehicle braking system, let Substituting into equation (1), and combining equations (1) and (2), we can obtain the steady-state solution of the vehicle braking system as follows: Introducing a new state variable φ=θ-θ0, substituting θ=φ+θ0 into equations (1) to (2), and using Gaussian white noise ξ(t) of intensity 2D to represent the uncertainty of the brake disc torsional stiffness, the equivalent stochastic dynamic model of vehicle brake flutter is obtained as follows:

[0100]

[0101] In the formula, ρ1 is the random control parameter of the torsional stiffness of the brake disc.

[0102] 2. Solution of target braking pressure under random parameter excitation

[0103] Let q = φ, Equation (3) can be transformed into

[0104]

[0105] In the formula, It is the system Hamiltonian function, m 11 =c 11 +c 12 p+c 13 p 2 , B(t) is a standard Weiner process. 11 c 11 c 12 c 13 σ 11 k 11 They are all intermediate variables.

[0106] Based on the stochastic averaging method, equation (4) can be transformed into a one-dimensional Iton stochastic differential equation as follows:

[0107] dH=m(H)dt+σ(H)dB(t) (29)

[0108] In the formula, m(H) is the drift coefficient, and σ(H) is the diffusion coefficient. The specific expression is as follows:

[0109]

[0110] In the formula, O(H) is a first-order infinitesimal with respect to H. 2 ) is a second-order infinitesimal with respect to H.

[0111] Based on the behavior analysis of the singular boundaries of the stochastic differential equations, the stochastic stability condition of the system for achieving vehicle braking stability control is as follows: The stability boundary of the vehicle braking pressure can be obtained as follows:

[0112] This invention constructs a stochastic dynamic model of vehicle braking flutter based on the Stribeck friction effect, studies the stochastic bifurcation characteristics of vehicle braking, obtains the stochastic instability conditions and boundaries of vehicle braking flutter, and designs a vehicle braking stability control method based on this, which is extremely important for improving vehicle braking stability. Therefore, the "vehicle braking stability control method and system considering stochastic parameters" proposed in this invention mainly establishes a stochastic dynamic model of vehicle braking flutter, obtains the Iton stochastic differential process and its drift coefficient and diffusion coefficient, solves the stochastic stability boundary of vehicle braking pressure under different driving conditions, and achieves effective suppression of vehicle braking flutter by adjusting the vehicle braking force.

[0113] The core advantage of the method described in this invention is that:

[0114] 1) Construct a dynamic model of vehicle braking flutter, collect wheel angular velocity, braking pressure on brake disc, and transmission torque signal on brake disc during vehicle braking, and establish an equivalent stochastic dynamic model of vehicle braking flutter considering stiffness uncertainty.

[0115] 2) The stochastic stability boundary of vehicle braking pressure is determined by the stochastic averaging method, the target braking pressure is solved in real time, and the vehicle braking vibration is suppressed by adjusting the wheel braking force, so as to provide technical support for better improving vehicle braking performance.

[0116] Example 2

[0117] Please see Figure 3 This is a schematic diagram illustrating the working principle of an automotive braking control system provided in Embodiment 2 of the present invention. The automotive braking control system is mainly used in automobiles to control the brake disc 3. After the automotive braking control system is installed in the automobile, it can be used to achieve stochastic stability control of the automobile during braking. This embodiment is one example of implementing the automotive braking control method in Embodiment 1, used to demonstrate the feasibility of the automotive braking control method in Embodiment 1.

[0118] The vehicle braking control system of this embodiment includes a pair of brake pads 5, a float caliper 6, a piston 7, a brake pressure regulator 8 for adjusting the braking pressure on the brake pads 5, and a vehicle braking stability control system for controlling the brake pressure regulator 8. The vehicle braking stability control system adjusts the braking pressure output by the brake pressure regulator 8 to the pair of brake pads 5. Specifically, the brake pressure regulator 8 applies braking pressure to the brake pads 5 by driving the piston 7, which, with the help of the float caliper 6, drives the pair of brake pads 5 to clamp the brake disc 3, thereby braking the brake disc 3. Adjusting the braking pressure output by the brake pressure regulator 8 changes the rotational speed of the brake disc 3, thereby changing the braking distance and braking speed of the vehicle when braking.

[0119] The function of the vehicle braking stability control system is to, when the brake pressure regulator 8 is engaged during braking, calculate the target braking pressure F based on the wheel angular velocity ω0 at the initial braking point, provided that the calibration conditions are met. N0 Adjust the brake pressure output from brake pressure regulator 8 to brake block 5 to F. N0 This system helps suppress vehicle braking vibration. Therefore, installing a vehicle braking stability control system allows for stable vehicle control during braking. The vehicle braking stability control system includes a data acquisition unit and an electronic control unit.

[0120] The data acquisition unit may include a torque sensor 12, a brake pressure sensor 13, and an angular velocity sensor 14. The torque sensor 12 is used to acquire the transmission torque T experienced by the brake disc 3 at the initial stage of vehicle braking; the pressure sensor 13 is used to acquire the brake pressure F on the brake pads 5 at the initial stage of vehicle braking. N ; Angular velocity sensor 14 is used to collect the wheel angular velocity ω0 at the initial braking of the vehicle.

[0121] Electronic control unit 9 is used to: determine whether λ is greater than or equal to λ0 when the vehicle brakes; if so, calculate the target braking pressure F based on the wheel angular velocity ω0 at the initial braking point. N0 Adjust the brake pressure output from the brake pressure regulator to the brake pads to F. N0 Otherwise, there is no need for vehicle braking stability control.

[0122] Among them, the angular velocity sensor 14 is a necessary component, while the torque sensor 12 and brake pressure sensor 13 are optional. When the vehicle braking stability control system directly uses the target brake pressure model in Example 1 to calculate F... N0 In this case, there is no need to additionally install torque sensor 12 and brake pressure sensor 13. Otherwise, torque sensor 12 and brake pressure sensor 13 need to be installed, and then the F output from these three sensors will be used to determine the braking force. N T, ω0, the electronic control unit 9 also needs to design the target braking pressure model (i.e., F) using the target braking pressure model design method introduced in Example 1. N0 (Calculation formula).

[0123] To demonstrate the effectiveness of the vehicle braking stability control system of the present invention, experimental data is provided in this embodiment.

[0124] The parameter for the example is I = 0.65 kg·m 2 , c=1N·m·s / rad, k=300000N·m / rad, R=0.12m, μ s =0.5, μ m =0.3, v m =5.6 rad / s, ρ1 = 500 N·m / rad, D = 0.15 s, then the stochastic stability boundary of braking pressure under different initial wheel braking angular velocities can be obtained as follows: Figure 4 As shown.

[0125] Furthermore, with the initial angular velocity of the wheel during braking ω0 = 3 rad / s, and the braking pressure F N1 =200N and F N2 Taking 230N as an example, solve for the dynamic response of the vehicle braking system as follows: Figure 5 As shown, when the braking pressure is F N1When the braking pressure reaches 200N, the braking pressure is adjusted to a stable range, and the vehicle's braking system response will converge. Clearly, the stochastic stability control method proposed in this invention can effectively suppress vehicle flutter and improve vehicle braking stability.

[0126] In summary, the core advantage of the method described in this invention is that:

[0127] 1) Construct a dynamic model of vehicle braking flutter, collect wheel angular velocity, brake disc rotation angle, brake pressure on brake disc, and transmission torque signal on brake disc during vehicle braking, and establish an equivalent stochastic dynamic model of vehicle braking flutter considering stiffness uncertainty.

[0128] 2) The stochastic stability boundary of vehicle braking pressure is determined by the stochastic averaging method, the target braking pressure is solved in real time, and the vehicle braking vibration is suppressed by adjusting the wheel braking force, so as to provide technical support for better improving vehicle braking performance.

[0129] The vehicle braking stability control system of this invention can upgrade the functions of old vehicles by adding a vehicle braking stability control function to the braking control function. In application, a wheel angular velocity sensor can be installed on the brake disc of the old vehicle to collect the wheel angular velocity ω0 at the initial braking of the vehicle. Finally, an electronic control unit that is linked to the brake pressure regulator of the old vehicle is installed in the vehicle to upgrade the functions of the old vehicle. Of course, it is also possible not to install an electronic control unit, but to design the functions of the electronic control unit as software, thereby patching the vehicle system of the old vehicle and performing the functions of the electronic control unit through the updated vehicle system.

[0130] Alternatively, for new vehicles designed with the functions of this invention, wheel angular velocity sensors may be installed at the factory, and the vehicle's onboard system may include a brake pressure regulator that can perform the functions of an electronic control unit, eliminating the need for consumers to purchase a separate vehicle braking stability control system.

[0131] Therefore, the technology of this invention can be well applied to both new and old cars, making it easy to promote and apply, and possessing high technological transformation value and commercial prospects.

[0132] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0133] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A vehicle braking stability control method considering random parameters, characterized in that, It includes the following steps: When a car brakes, and λ≥λ0, the target braking pressure F is calculated based on the wheel angular velocity ω0 at the initial moment of braking. N0 ; Adjust the brake pressure output from the brake pressure regulator to the brake pads to F. N0 ; Wherein, λ is the frequency ratio of the vehicle's braking angular velocity response; λ0 is the calibrated threshold; c is the torsional damping of the brake disc, D is Gaussian white noise, and κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ s μ m v m ρ1 and k are the static friction coefficient, sliding friction coefficient, sliding angular velocity, and torsional stiffness of the brake disc, respectively. ρ1 is a random control parameter of k, and R is the equivalent radius of action of the brake block on the brake disc.

2. The vehicle braking stability control method considering random parameters according to claim 1, characterized in that, When λ < λ0, vehicle braking stability control is not required during vehicle braking.

3. The vehicle braking stability control method considering random parameters according to claim 1, characterized in that, λ is: Among them, f s It is the dominant frequency of the brake disc's angular velocity response, f. t It is the calibrated frequency of vehicle braking vibration.

4. The vehicle braking stability control method considering random parameters according to claim 1, characterized in that, F N0 The design methodology includes the following steps: Establish a system that includes ω0 and the braking pressure F on the brake disc at the initial moment of braking. N A single-degree-of-freedom dynamic model of the transmission system torque T: In the formula, θ, These are the brake disc's rotation angle, angular velocity, and acceleration, respectively; I is the brake disc's moment of inertia; F μ This is the braking friction force acting on the brake disc. Based on the Stribeck friction effect, its polynomial expression is as follows: In the formula, It is the angular velocity of the brake disc relative to the brake pads, sgn(v r ) is a sign function; To solve for the steady-state solution of the vehicle braking system, let Substituting into equation (1), and combining equations (1) and (2), we obtain the steady-state solution of the vehicle braking system as follows: Introducing a new state variable φ=θ-θ0, and substituting θ=φ+θ0 into equations (1) to (2), while using 2D Gaussian white noise ξ(t) to represent the uncertainty of the brake disc torsional stiffness, the equivalent stochastic dynamic model of vehicle brake flutter is obtained as follows: Let q = φ, Transform equation (3) into In the formula, It is the system Hamiltonian function, m 11 =c 11 +c 12 p+c 13 p 2 , B(t) is a standard Weiner process; Based on the stochastic averaging method, equation (4) is transformed into a one-dimensional Iton stochastic differential equation. dH=m(H)dt+σ(H)dB(t) (5) In the formula, m(H) is the drift coefficient, and σ(H) is the diffusion coefficient, specifically expressed as follows: In the formula, O(H) is a first-order infinitesimal with respect to H. 2 ) is a second-order infinitesimal with respect to H; Based on the behavior analysis of the singular boundaries of the stochastic differential equations, the stochastic stability condition of the system for achieving vehicle braking stability control is as follows: The stability boundary of the vehicle braking pressure is F. N0 .

5. A vehicle braking stability control system considering random parameters, characterized in that, It includes: An angular velocity sensor is used to collect the wheel angular velocity ω0 at the initial stage of vehicle braking. The electronic control unit, used during vehicle braking, calculates the target braking pressure F based on the wheel angular velocity ω0 at the initial moment of braking, provided that λ≥λ0. N0 And adjust the braking pressure output from the brake pressure regulator to the brake pads to F. N0 ; Wherein, λ is the frequency ratio of the vehicle's braking angular velocity response; λ0 is the calibrated threshold; c is the torsional damping of the brake disc, D is Gaussian white noise, and κ1 = 1.5(|μ s |-|μ m |) / |v m |,κ3=0.5(|μ s |-|μ m |) / |v m | 3 μ s μ m v m ρ1 and k are the static friction coefficient, sliding friction coefficient, sliding angular velocity, and torsional stiffness of the brake disc, respectively. ρ1 is a random control parameter of k, and R is the equivalent radius of action of the brake block on the brake disc.

6. The vehicle braking stability control system considering random parameters according to claim 5, characterized in that, λ is: Among them, f s It is the dominant frequency of the brake disc's angular velocity response, f. t It is the calibrated frequency of vehicle braking vibration.

7. The vehicle braking stability control system considering random parameters according to claim 5, characterized in that, The vehicle braking stability control system also includes F N0 Design system, F N0 The design system includes: The angular velocity sensor; A brake pressure sensor is used to collect the brake pressure F of the brake disc at the initial stage of vehicle braking. N ; A torque sensor is used to collect the torque T of the brake disc when the car is initially braking. Designer, used according to F N T design F N0 F N0 The design methodology includes the following steps: Establish a system containing ω0 and F N Single-degree-of-freedom dynamic model of T: In the formula, θ, These are the brake disc's rotation angle, angular velocity, and acceleration, respectively; I is the brake disc's moment of inertia; F μ It is the braking friction force on the brake disc, based on the Stribeck friction effect, and its polynomial expression is as follows. In the formula, It is the angular velocity of the brake disc relative to the brake pads, sgn(v r ) is a sign function; To solve for the steady-state solution of the vehicle braking system, let Substituting into equation (1), and combining equations (1) and (2), we obtain the steady-state solution of the vehicle braking system as follows: Introducing a new state variable φ=θ-θ0, and substituting θ=φ+θ0 into equations (1) to (2), while using 2D Gaussian white noise ξ(t) to represent the uncertainty of the brake disc torsional stiffness, the equivalent stochastic dynamic model of vehicle brake flutter is obtained as follows: Let q = φ, Transform equation (3) into In the formula, It is the system Hamiltonian function, m 11 =c 11 +c 12 p+c 13 p 2 , B(t) is a standard Weiner process; Based on the stochastic averaging method, equation (4) is transformed into a one-dimensional Iton stochastic differential equation. dH=m(H)dt+σ(H)dB(t) (11) In the formula, m(H) is the drift coefficient, and σ(H) is the diffusion coefficient. The specific expression is as follows: In the formula, O(H) is a first-order infinitesimal with respect to H. 2 ) is a second-order infinitesimal with respect to H; Based on the behavior analysis of the singular boundaries of the stochastic differential equations, the stochastic stability condition of the system for achieving vehicle braking stability control is as follows: The stability boundary of the vehicle braking pressure is F. N0 .

8. A method for controlling vehicle braking, characterized in that, When the vehicle brakes, it adopts the vehicle braking stability control method considering random parameters as described in any one of claims 1 to 4, and adjusts the braking pressure output from the brake pressure regulator to the brake pads to achieve braking control of the vehicle's brake disc.

9. A vehicle braking control system, comprising: Brake pressure regulator, used to adjust the brake pressure on the brake pads; The vehicle braking control system is characterized in that it further includes a vehicle braking stability control system considering random parameters as described in any one of claims 5 to 7 for controlling the brake pressure regulator.

10. A car, characterized in that, It is equipped with the vehicle braking control system as described in claim 9, which is used to achieve random stability control of the vehicle during braking.

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