Method and device for determining braking force of vehicle

Abstract

The invention discloses a vehicle braking force determination method and device. The method comprises the steps that the minimum wheel slip rate corresponding to each axle of a vehicle serves as a target, and a target function is constructed; based on the target constraint condition, the minimum wheel slip rate corresponding to each axle of the target function under the target braking strength and the braking force distribution result corresponding to the minimum wheel slip rate are solved, the target constraint conditions include that the wheel slip rates corresponding to all the axles are different and conform to the preset locking sequence of all the axles, the wheel slip rates of all the axles determine the longitudinal adhesion coefficients corresponding to all the axles, and the longitudinal adhesion coefficients corresponding to all the axles determine the braking force distribution results corresponding to all the axles; and the sum of the braking force distribution results corresponding to the axles is equal to the total adhesive force corresponding to the target braking strength, and the safety and stability of the vehicle can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vehicle braking force, and particularly relates to a method and device for determining vehicle braking force. BACKGROUND

[0002] For the distribution of braking force of a vehicle, a traditional braking force distribution system distributes braking force to the vehicle in a fixed ratio, which is difficult to meet the needs of a vehicle with a large change in load. An electronic braking force distribution system can distribute braking force of a vehicle in real time according to the state of the vehicle and the road surface.

[0003] At present, there is a lack of a method for distributing braking force of a vehicle with a large change in load by using an electronic braking force distribution system, which leads to difficulty in improving the stability and safety of the vehicle with a large change in load. SUMMARY

[0004] The embodiments of the application provide a method and device for determining vehicle braking force, which can improve the safety and stability of a vehicle.

[0005] In a first aspect, the embodiments of the application provide a method for determining vehicle braking force, comprising: constructing a target function with the minimum wheel slip rate of each axle of a vehicle as a target; and solving the minimum wheel slip rate of each axle of the vehicle and a braking force distribution result corresponding to the minimum wheel slip rate under a target braking intensity based on a target constraint condition, wherein the target constraint condition comprises that the wheel slip rate of each axle is different and meets a preset locking sequence of each axle, the wheel slip rate of each axle determines a longitudinal adhesion coefficient of each axle, the longitudinal adhesion coefficient of each axle determines the braking force distribution result of each axle, and the sum of the braking force distribution result of each axle is equal to a total adhesion force corresponding to the target braking intensity.

[0006] In an optional embodiment of the first aspect, the wheel slip rate of each axle is different and meets the preset locking sequence of each axle, comprising: the wheel slip rate of a target axle is equal to the product of the wheel slip rate of each other axle and a weight coefficient corresponding to each other axle, the target axle is an axle with the maximum wheel slip rate among the axles, each other axle is an axle other than the target axle among the axles, the weight coefficient is set according to the preset locking sequence, and the weight coefficient is greater than 1.

[0007] In an optional embodiment of the first aspect, the target function is constructed with the minimum wheel slip rate of each axle of the vehicle as a target, comprising: the target function is constructed based on the sum of squares of the wheel slip rate of each axle.

[0008] In an optional embodiment of the first aspect, the vehicle includes a tractor and at least one semi-trailer, the tractor and the at least one semi-trailer are connected via a saddle, and the axles include a front axle of the tractor, a rear axle of the tractor, and at least one axle of the semi-trailer; with the goal of minimizing the wheel slip rate corresponding to each axle of the vehicle, constructing an objective function includes: constructing Among them, J(λ f ,λ m ,λ r ) is used to represent the objective function, λ f Used to express the wheel slip rate of the tractor's front axle, λ m Used to express the wheel slip rate of the tractor's rear axle, λ r Used to indicate the wheel slip rate of a semi-trailer axle.

[0009] In an optional embodiment of the first aspect, the wheel slip rates corresponding to the axles are different and conform to the preset locking order of the axles, including: f =ε m λ m and λ f =ε r λ r , so that the wheel slip rates corresponding to each axle are different and conform to the preset locking order of each axle, ε m Used to represent the weight coefficient corresponding to the rear axle of the tractor, ε r Used to represent the weight coefficient corresponding to the semi-trailer axle, ε m >1,ε r >1 and ε m >ε r .

[0010] In an optional embodiment of the first aspect, the target constraint condition further includes: based on F Hx =W2z-F xr , so that the longitudinal force at the saddle is balanced, where F Hx is the longitudinal force transmitted from the tractor to the semi-trailer by the saddle, W2 is the weight of the semi-trailer, z is the braking strength, F xr The braking force distribution results for the semi-trailer axles.

[0011] In an optional embodiment of the first aspect, the longitudinal adhesion coefficient corresponding to each axle determines the braking force distribution result corresponding to each axle, including: based on The longitudinal adhesion coefficient corresponding to the front axle of the tractor determines the braking force distribution result corresponding to the front axle of the tractor, F xf Used to indicate the braking force distribution result of the tractor's front axle. Used to express the longitudinal adhesion coefficient of the front axle of the tractor, F zf Used to represent the vertical force on the front axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the tractor rear axle determines the braking force distribution result corresponding to the tractor rear axle, F xm The braking force distribution result corresponding to the tractor rear axle, The longitudinal adhesion coefficient corresponding to the tractor rear axle, F zm is the vertical force of the tractor rear axle; based on The longitudinal adhesion coefficient corresponding to the tractor rear axle determines the braking force distribution result corresponding to the tractor rear axle, F xr is the braking force distribution result of the tractor rear axle, The longitudinal adhesion coefficient corresponding to the tractor rear axle, F zr The vertical force of the tractor rear axle.

[0012] In an optional embodiment of the first aspect, the process of determining the vertical force of the tractor front axle, the vertical force of the tractor rear axle and the vertical force of the tractor rear axle of the tractor includes: constructing the vertical force balance equation and the moment balance equation of the tractor, the vertical force balance equation of the tractor and the vertical moment balance equation of the saddle; the vertical force balance equation and the moment balance equation of the tractor, the vertical force balance equation of the tractor and the vertical moment balance equation of the saddle are solved to obtain the vertical force of the tractor front axle, the vertical force of the tractor rear axle and the vertical force of the tractor rear axle of the tractor.

[0013] In an optional embodiment of the first aspect, the wheel slip rate of each axle determines the longitudinal adhesion coefficient corresponding to each axle, including: based on The wheel slip rate of the tractor front axle determines the longitudinal adhesion coefficient corresponding to the tractor front axle, The longitudinal adhesion coefficient corresponding to the tractor front axle; based on The wheel slip rate of the tractor rear axle determines the longitudinal adhesion coefficient corresponding to the tractor rear axle, The longitudinal adhesion coefficient corresponding to the tractor rear axle; based on The wheel slip rate of the tractor rear axle determines the longitudinal adhesion coefficient corresponding to the tractor rear axle, The longitudinal adhesion coefficient corresponding to the tractor rear axle; wherein c1, c2 and c3 are fitting parameters.

[0014] In a second aspect, the embodiments of the present application provide a vehicle braking force determination apparatus, comprising: a construction module configured to construct a target function with a minimum wheel slip rate of each axle of a vehicle as a target; and a determination module configured to solve the minimum wheel slip rate of each axle and a braking force distribution result corresponding to the minimum wheel slip rate under a target braking intensity based on a target constraint condition, wherein the target constraint condition comprises that the wheel slip rates of each axle are different and meet a preset locking sequence of each axle, the wheel slip rates of each axle determine longitudinal adhesion coefficients of each axle, the longitudinal adhesion coefficients of each axle determine the braking force distribution result of each axle, and a sum of the braking force distribution result of each axle is equal to a total adhesion force corresponding to the target braking intensity.

[0015] In the embodiments of the present application, the target function can be constructed with the minimum wheel slip rate of each axle of the vehicle as the target, the wheel slip rates of each axle are set to be different and meet the preset locking sequence of each axle to avoid brake instability of the vehicle under extreme working conditions and improve the stability of the vehicle. The wheel slip rates of each axle determine the longitudinal adhesion coefficients of each axle, the longitudinal adhesion coefficients of each axle determine the braking force distribution result of each axle, and the sum of the braking force distribution result of each axle is equal to the total adhesion force under the target braking intensity, so that the vehicle is in a stable state whether it is stationary or moving at a constant speed. By using the longitudinal adhesion coefficients, the braking force distribution result of each axle can be adjusted based on the wheel slip rates of each axle, and the braking force can be reasonably distributed to each axle. It can be seen that, under the constraint of the target constraint condition, the target function is solved to obtain the minimum wheel slip rate of each axle and the braking force distribution result under the state of the minimum overall slip rate, so that the braking force distribution result of each axle is more reasonable, thereby improving the stability and safety of the vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced as follows, and other drawings can also be obtained by those of ordinary skill in the art without creative labor on the basis of these drawings.

[0017] Figure 1 is a flowchart of a vehicle braking force determination method provided by an embodiment of the present application;

[0018] Figure 2 is a force schematic diagram of a semitrailer train provided by another embodiment of the present application;

[0019] Figure 3 is a flowchart of a semitrailer train braking force determination method provided by an embodiment of the present application;

[0020] Figure 4a is a schematic diagram of target braking intensity and vertical force provided by one embodiment of the present application;

[0021] Figure 4b and Figure 4c is a schematic diagram of target braking intensity and wheel slip rate provided by one embodiment of the present application;

[0022] Figure 4d is a schematic diagram of target braking intensity and braking force distribution result provided by one embodiment of the present application;

[0023] Figure 5 is a schematic diagram of a structure of a vehicle braking force determination apparatus provided by one embodiment of the present application;

[0024] Figure 6 is a schematic diagram of a structure of an electronic device provided by another embodiment of the present application.

[0025] The above drawings include the following reference signs:

[0026] 500, vehicle braking force determination apparatus; 510, construction module; 520, determination module; 601, processor; 602, memory; 603, communication interface; 610, bus. DETAILED DESCRIPTION

[0027] The features and exemplary embodiments of the various aspects of the present application will be described in detail below with reference to the drawings. To make the purpose, technical solutions and advantages of the present application more clear, the present application will be further described in detail below with reference to the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, but not to limit the present application. The present application can be implemented without some of the specific details by those skilled in the art. The following description of the embodiments is only to provide a better understanding of the present application by showing examples of the present application.

[0028] It should be noted that, in this document, relational terms such as first and second, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement "comprising" does not exclude the existence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0029] For the distribution of braking force of a vehicle, a traditional braking force distribution system distributes braking force to the vehicle in a fixed ratio, which is difficult to meet the needs of a vehicle with a large change in load. An electronic braking force distribution system can distribute braking force to the vehicle in real time according to the state of the vehicle and the road surface.

[0030] At present, there is a lack of methods for distributing braking force to a vehicle with a large change in load by using an electronic braking force distribution system, which makes it difficult to improve the stability and safety of the vehicle with a large change in load.

[0031] For example, a semi-trailer truck has very high flexibility, and it can change the type of trailer at any time according to the needs, so the overall mass of this type of vehicle changes greatly. Compared with a traditional two-axle vehicle, a semi-trailer truck connects the tractor and the semi-trailer together through a saddle. During braking, the tractor and the semi-trailer move coupled and affect each other, which is easy to produce limit conditions such as fishtailing and folding, thereby making it difficult to improve the stability and safety of the semi-trailer truck.

[0032] To improve the stability and safety of the semi-trailer truck, a target function can be constructed based on the wheel slip rates of each axle of the semi-trailer truck, the interaction between the tractor and the semi-trailer is considered, the longitudinal adhesion coefficients of each axle of the semi-trailer truck are calculated based on a tire model, and the braking force distribution method of the semi-trailer truck is converted into a nonlinear programming problem with linear and nonlinear constraints.

[0033] Before determining the braking force of the semi-trailer truck, the following assumptions can be made:

[0034] 1. The adhesion conditions of each wheel of the tractor and the semi-trailer on the ground are the same.

[0035] 2. The influence of wheel inertia on the vertical force of the axle is not considered.

[0036] 3. It is assumed that the braking forces of the left and right wheels of the semi-trailer truck are the same.

[0037] 4. The tractor and the semi-trailer are rigidly connected, and the tractor and the semi-trailer maintain the same braking deceleration at each instant.

[0038] 5. The mass center position of the tractor and the semi-trailer does not change during movement.

[0039] Embodiments of the present application provide a method and apparatus for determining vehicle braking force. With the goal of minimizing the wheel slip ratio corresponding to each axle of the vehicle, an objective function can be constructed. By setting different wheel slip ratios for each axle and conforming to a preset locking order for each axle, this method prevents vehicle braking instability under extreme operating conditions and improves vehicle stability. By setting the wheel slip ratios of each axle to determine the longitudinal adhesion coefficient of each axle, the longitudinal adhesion coefficients of each axle to determine the braking force distribution results for each axle, and the sum of the braking force distribution results for each axle to equal the total adhesion at a target braking intensity, the vehicle remains stable whether stationary or in constant motion. By utilizing the longitudinal adhesion coefficient, the braking force distribution results for each axle can be adjusted based on the wheel slip ratio of each axle, thereby rationally allocating braking force to each axle. Thus, within the constraints of the objective constraints, the present application solves the objective function to obtain the minimum wheel slip ratio and braking force distribution results for each axle when the overall slip ratio is minimized. This ensures a more rational braking force distribution result for each axle, thereby improving vehicle stability and safety.

[0040] In an embodiment of the present application, the method for determining the vehicle braking force provided in the embodiment of the present application can be implemented when the processor of an electronic device executes a program or instruction. However, in some embodiments, the electronic control unit (Electronic Control Unit, ECU) of the vehicle or other devices may also have similar functions. For example, the method for determining the vehicle braking force provided in the embodiment of the present application is implemented when the electronic control unit of the vehicle executes a program or instruction. The embodiment of the present application does not limit this.

[0041] It should be noted that the application scenarios described in the above embodiments of the present application are intended to more clearly illustrate the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions provided by the embodiments of the present application. Persons skilled in the art will appreciate that as new application scenarios emerge, the technical solutions provided by the embodiments of the present application will also be applicable to similar technical problems. The method for determining vehicle braking force provided in the embodiments of the present application can be applied to various application scenarios requiring the distribution of vehicle braking force.

[0042] For ease of understanding, here, taking the determination of the braking force of a semi-trailer vehicle train as an example, a brief introduction is given to the method and device for determining the vehicle braking force provided in this application.

[0043] Figure 1 FIG. 1 is a flow chart showing a method for determining vehicle braking force according to an embodiment of the present application. Figure 1 As shown, the method for determining the vehicle braking force provided in the embodiment of the present application includes step S101 and step S102.

[0044] In step S101, a target function is constructed with the minimum wheel slip ratio of each axle of the vehicle as the target.

[0045] The wheel slip ratio refers to the proportion of the sliding component in the wheel movement.

[0046] When the vehicle brakes, the greater the lateral reaction force of the ground on the wheel, the stronger the anti-sideslip ability of the vehicle, and the lateral force is closely related to the wheel slip ratio. When the wheel slip ratio is 0, the lateral reaction force of the vehicle is the largest. As the wheel slip ratio increases, the lateral reaction force of the vehicle rapidly decreases, and a small lateral disturbance can cause the vehicle to sideslip. If the rear axle of the vehicle locks before the front axle, a small lateral disturbance can cause the vehicle to spin and other dangerous working conditions. Therefore, the braking stability of the vehicle depends on whether the wheel locks and the locking order of the wheel. Whether the wheel locks can be indicated by the wheel slip ratio, and the greater the wheel slip ratio, the higher the component of the wheel slip, and the more likely the wheel locks.

[0047] For the target function constructed with the minimum wheel slip ratio of each axle of the vehicle as the target, there can be multiple implementation manners.

[0048] In one embodiment, the target function is constructed based on the sum of the wheel slip ratios of each axle.

[0049] The sum of the wheel slip ratios of each axle can be used to directly calculate the overall slip ratio of the vehicle.

[0050] In another embodiment, the target function is constructed based on the sum of the squares of the wheel slip ratios of each axle.

[0051] The greater the wheel slip ratio, the greater the possibility of locking the corresponding axle, which can cause the braking distance of the vehicle to be longer or the vehicle to lose the steering ability. By constructing the target function based on the sum of the squares of the wheel slip ratios of each axle, the larger wheel slip ratio can have a larger proportion in the overall slip ratio of the vehicle, so that the possible slip situation can be focused on and controlled, and the safety and stability of the vehicle are further improved.

[0052] In the case of a vehicle being a semitrailer train, the vehicle can include a tractor and at least one semitrailer, the tractor and the at least one semitrailer being connected through a saddle, and each axle includes a tractor front axle, a tractor rear axle, and at least one semitrailer axle. Based on the sum of the squares of the wheel slip ratios of each axle, the target function can be constructed as wherein J(λ f ,λ m ,λ r ) is used to represent the target function, λ f is used to represent the wheel slip ratio of the tractor front axle, λ mλ r λ

[0053] Based on the square sum of the wheel slip rate of the front axle of the tractor, the square sum of the wheel slip rate of the rear axle of the tractor, and the square sum of the wheel slip rate of the axle of the semitrailer, the overall slip rate of the semitrailer train is constructed. Through the form of the square sum, the slip of each axle can be better focused, and the safety and stability of the semitrailer train are further improved.

[0054] In step S102, based on the target constraint condition, the minimum wheel slip rate of each axle corresponding to the target braking intensity of the target function is solved, and the braking force distribution result corresponding to the minimum wheel slip rate, wherein the target constraint condition includes: the wheel slip rates of each axle are different and meet the preset locking sequence of each axle, the wheel slip rates of each axle determine the longitudinal adhesion coefficients of each axle, the longitudinal adhesion coefficients of each axle determine the braking force distribution result of each axle, and the sum of the braking force distribution results of each axle is equal to the total adhesion force corresponding to the target braking intensity.

[0055] The braking intensity is an important indicator to measure the braking ability of the vehicle. From the physical meaning, the braking intensity refers to the ratio of the vehicle braking deceleration to the gravitational acceleration. In actual application scenarios, the braking intensity can directly reflect the intensity of the vehicle braking.

[0056] The braking force is the force that hinders the movement of the vehicle during braking. The braking force distribution result of each axle is the braking force distributed to each axle under the condition that the overall slip rate of the vehicle is minimum and the wheel slip rate of each axle is minimum.

[0057] Since the locking of the axle is related to the wheel slip rate, in order to improve the braking stability of the vehicle, the wheel slip rates of each axle are set to be different and meet the preset locking sequence of each axle. Specifically, the wheel slip rate of the target axle is equal to the product of the wheel slip rate of each other axle and the weight coefficient corresponding to each other axle, the target axle is the axle with the maximum wheel slip rate among the axles, each other axle is an axle other than the target axle among the axles, and the weight coefficient is set according to the preset locking sequence and is greater than 1.

[0058] Setting the product of the wheel slip rate of each other axle and the weight coefficient corresponding to each other axle to be equal to the wheel slip rate of the target axle can make the wheel slip rate of the target axle be the maximum among the axles, i.e., the target axle is the first to lock. Setting the weight coefficient of each other axle according to the preset locking sequence can control the locking sequence of the other axles other than the target axle among the axles according to the weight coefficient, so that the axles can lock according to the preset locking sequence.

[0059] In one embodiment, in the case of the vehicle being a tractor-semitrailer, λ f = ε m λ m and λ f = ε r λ r are set to make the wheel slip ratios of the respective axles different and in accordance with a preset locking sequence, ε m is used to represent the weight coefficient corresponding to the rear axle of the tractor, ε r is used to represent the weight coefficient corresponding to the axle of the semitrailer, ε m > 1, ε r > 1 and ε m > ε r .

[0060] For a tractor-semitrailer, the requirement for braking stability is that the tractor-semitrailer does not fold, spin, and the semitrailer does not collide with the tractor, and the like. Therefore, in the case of a low or more extreme longitudinal adhesion coefficient, the reasonable locking sequence of the tractor-semitrailer should be: first the front axle of the tractor, then the axle of the semitrailer, and finally the rear axle of the tractor. In order to achieve the locking sequence of “first the front axle of the tractor, then the axle of the semitrailer, and finally the rear axle of the tractor”, λ f = ε m λ m and λ f = ε r λ r are set, so that the wheel slip ratio of the front axle of the tractor is the largest, i.e., the front axle of the tractor is the first to lock. Since ε m > ε r , the wheel slip ratio of the rear axle of the tractor is less than the wheel slip ratio of the axle of the semitrailer, so that the locking sequence of the axles of the tractor, the rear axle of the tractor, and the axle of the semitrailer is in accordance with the preset locking sequence.

[0061] In one embodiment, in the case of the vehicle being a tractor-semitrailer, the target constraint condition further comprises: based on F Hx = W2z - F xr , balancing the longitudinal force at the saddle, wherein F Hx is the longitudinal force transmitted from the tractor to the semitrailer at the saddle, W2 is the weight of the semitrailer, z is the braking intensity, and F xr is the braking force distribution result of the axle of the semitrailer.

[0062] The tractor-semitrailer includes a tractor and a semitrailer, and the tractor and the semitrailer are connected through a saddle. The movements of the tractor and the semitrailer are coupled and influenced each other during braking. If the longitudinal force at the saddle is unbalanced, the tractor-semitrailer may spin or fold, and the like. By setting FHx = W2z - F xr The longitudinal force at the saddle is balanced, so that the problems such as fishtailing and folding of the semi-trailer vehicle train can be avoided.

[0063] In actual application, the longitudinal force at the saddle is not limited to be balanced by analysis, so that the overall force of the semi-trailer vehicle train is balanced. The longitudinal force of the traction connecting device can also be analyzed to balance the overall force of the semi-trailer vehicle train. The traction connecting device is other connecting components except the saddle.

[0064] In an embodiment, the longitudinal adhesion coefficient corresponding to each axle determines the braking force distribution result corresponding to each axle, including: The longitudinal adhesion coefficient corresponding to the front axle of the tractor determines the braking force distribution result corresponding to the front axle of the tractor, F xf is used to represent the braking force distribution result of the front axle of the tractor, is used to represent the longitudinal adhesion coefficient of the front axle of the tractor, F zf is the vertical force of the front axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the rear axle of the tractor determines the braking force distribution result corresponding to the rear axle of the tractor, F xm is used to represent the braking force distribution result of the rear axle of the tractor, is used to represent the longitudinal adhesion coefficient of the rear axle of the tractor, F zm is the vertical force of the rear axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the axle of the semi-trailer determines the braking force distribution result corresponding to the axle of the semi-trailer, F xr is the braking force distribution result of the axle of the semi-trailer, is used to represent the longitudinal adhesion coefficient of the axle of the semi-trailer, F zr is used to represent the vertical force of the axle of the semi-trailer.

[0065] The longitudinal adhesion coefficient is used to represent the adhesion ability between the tire and the ground in the longitudinal direction (the driving direction of the vehicle). There are many ways to determine the longitudinal adhesion coefficient of the vehicle.

[0066] In an embodiment, the traction test method can be used to determine the longitudinal adhesion coefficient of the vehicle. Specifically, the tractor is used to pull the measured vehicle, the traction force and the vertical load of the tractor are measured, and the longitudinal adhesion coefficient of the vehicle is determined.

[0067] In another embodiment, the empirical formula method can be used to determine the longitudinal adhesion coefficient of each axle. Specifically, the longitudinal adhesion coefficient of each axle can be estimated based on the empirical formula according to the road surface type and condition.

[0068] For example, the Burckhardt tire model is a mathematical model used to describe the adhesion characteristics between the tire and the road surface. The Burckhardt tire model is a tire empirical model proposed on the basis of the classic magic formula tire model through theoretical derivation and simulation analysis, and can accurately reflect the relationship between the longitudinal adhesion coefficient and the wheel slip rate of the tire under different road conditions. The Burckhardt tire model can be used in the embodiment to determine the longitudinal adhesion coefficients of the axles.

[0069] Specifically, based on determining the wheel slip rate of the front axle of the tractor to determine the corresponding longitudinal adhesion coefficient of the front axle of the tractor, for representing the longitudinal adhesion coefficient of the front axle of the tractor; based on determining the wheel slip rate of the rear axle of the tractor to determine the corresponding longitudinal adhesion coefficient of the rear axle of the tractor, for representing the longitudinal adhesion coefficient of the rear axle of the tractor; based on determining the wheel slip rate of the axle of the semitrailer to determine the corresponding longitudinal adhesion coefficient of the axle of the semitrailer, for representing the longitudinal adhesion coefficient of the axle of the semitrailer; wherein c1, c2 and c3 are fitting parameters.

[0070] Since the mathematical expression of the Burckhardt tire model is relatively simple, based on the Burckhardt tire model, the longitudinal adhesion coefficients of the front axle of the tractor, the rear axle of the tractor and the axle of the semitrailer can be determined relatively quickly and simply.

[0071] In some examples, based on the Burckhardt tire model, the longitudinal adhesion coefficients of the front axle of the tractor, the rear axle of the tractor and the axle of the semitrailer are also represented as:

[0072]

[0073] wherein λ n for representing the wheel slip rate of the front axle of the tractor, the rear axle of the tractor and the axle of the semitrailer, the subscript n can be f, m or r, when the subscript n = f, for representing the longitudinal adhesion coefficient of the front axle of the tractor, when the subscript n = m, for representing the longitudinal adhesion coefficient of the rear axle of the tractor, when the subscript n = r, for representing the longitudinal adhesion coefficient of the axle of the semitrailer, c1, c2 and c3 are fitting parameters related to the road surface state.

[0074] The load distribution on each axle, road conditions, and vehicle driving state all affect the wheels on the corresponding axle. Because the wheel slip rate of each axle determines its longitudinal adhesion coefficient, using the longitudinal adhesion coefficient allows for real-time monitoring of the wheel slip rate dynamics of the corresponding axle. Based on the longitudinal adhesion coefficient and vertical force of each axle, the braking force distribution for each axle is determined. This allows for more reasonable braking force distribution to each axle while the vehicle is stable.

[0075] In one embodiment, the process of determining the vertical force of the front axle of the tractor, the vertical force of the rear axle of the tractor, and the vertical force of the axle of the semi-trailer includes: constructing the vertical force balance equation and the torque balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the vertical force and torque balance equation of the saddle; and simultaneously solving the vertical force balance equation and the torque balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the vertical force and torque balance equation of the saddle to obtain the vertical force of the front axle of the tractor, the vertical force of the rear axle of the tractor, and the vertical force of the axle of the semi-trailer.

[0076] Combined with Figure 2 The force diagram of the tractor and semi-trailer shown in the figure takes the tractor as the research object, and the vertical force balance equation of the tractor can be expressed as:

[0077] F zf +F zm -F Hz -W1=0

[0078] Among them, F zf Used to express the vertical force on the front axle of the tractor, F zm Used to express the vertical force on the rear axle of the tractor, F Hz It is used to indicate the vertical force of the saddle, and W1 is used to indicate the weight of the tractor.

[0079] Taking the torque from the front axle of the tractor, the torque balance equation of the tractor can be expressed as:

[0080] W1L1+F HZ L Hf -W1zh1-F Hx HF zm L f =0

[0081] Among them, L1 is used to represent the distance between the center of mass of the tractor and the front axle of the tractor, L Hf It is used to indicate the distance between the saddle and the front axle of the tractor, z is used to indicate the braking strength, h1 is used to indicate the height between the center of mass of the tractor and the ground, F Hx It is used to indicate the longitudinal force transmitted from the tractor to the semi-trailer by the saddle. H is used to indicate the height between the saddle and the ground. L fis used to represent the distance between the front axle of the tractor and the rear axle of the tractor.

[0082] Taking the semitrailer as the research object, the vertical force balance equation of the semitrailer can be expressed as:

[0083] F zr +F Hz -W2=0

[0084] Wherein, F zr is used to represent the vertical force of the semitrailer axle, and W2 is used to represent the weight of the semitrailer.

[0085] Taking the moment of the saddle, the moment balance equation of the saddle can be expressed as:

[0086] W2L Hr -W2z(h2-H)-F zr L r -F xr H=0

[0087] Wherein, L Hr is used to represent the distance between the center of mass of the semitrailer and the saddle, h2 is used to represent the height between the center of mass of the semitrailer and the ground, L r is used to represent the distance between the semitrailer axle and the saddle, and F xr is the braking force distribution result of the semitrailer axle.

[0088] Solving the vertical force balance equation of the tractor, the moment balance equation of the tractor, the vertical force balance equation of the semitrailer, and the moment balance equation of the saddle together can obtain:

[0089] The vertical force of the front axle of the tractor is:

[0090] The vertical force of the rear axle of the tractor is:

[0091] The vertical force of the semitrailer axle is:

[0092] The vertical force of the saddle is:

[0093] In the actual application process, when the force balance analysis of the tractor is carried out, it is not limited to taking the moment of the front axle of the tractor to obtain the moment balance equation of the tractor, but also can take the moment of other parts of the tractor to obtain the moment balance equation of the tractor, for example, the moment of the rear axle of the tractor can also be taken to obtain the moment balance equation of the tractor.

[0094] Compared with taking the torque from the rear axle of the tractor, taking the torque from the front axle of the tractor can more easily obtain the torque balance equation of the tractor, and the overall calculation can be simpler during the solution process.

[0095] For a vehicle that is stationary or moving at a constant speed, according to Newton's first law, the sum of the external forces acting on the vehicle must be zero. Therefore, the vehicle's equilibrium state can be analyzed based on the force balance equation, ensuring that the vehicle is in equilibrium whether stationary or moving at a constant speed. When analyzing the balance of a vehicle in a dynamic state such as acceleration, braking, or cornering, in addition to considering static balance, the influence of inertia and other dynamic factors must also be considered. Therefore, the vehicle's equilibrium state can be analyzed using the moment balance equation.

[0096] By simultaneously solving the constructed vertical force balance equation of the tractor, the moment balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the moment balance equation of the saddle, the vertical forces of the tractor's front axle, the tractor's rear axle, and the semi-trailer's axle can be accurately calculated based on the statics and dynamics principles of the vehicle, and further, the braking forces of the tractor's front axle, the tractor's rear axle, and the semi-trailer's axle can be distributed more reasonably.

[0097] To ensure that the longitudinal adhesion coefficient of each axle is fully utilized and the vehicle stability is maximized during braking, in one embodiment, the sum of the braking force distribution results corresponding to each axle is equal to the total adhesion corresponding to the target braking intensity.

[0098] Adhesion refers to the force that can be generated on the contact surface to prevent the wheel from sliding when the tire and the ground contact and interact with each other.

[0099] In the case of a semi-trailer train, the sum of the braking force distribution results corresponding to each axle is equal to the total adhesion corresponding to the target braking intensity, which can be expressed as:

[0100] F xf +F xm +F xr =(W1+W2)z

[0101] Among them, F xf Used to indicate the braking force distribution result of the front axle of the tractor, F xm Used to indicate the braking force distribution result of the tractor's rear axle, F xr The braking force distribution results for the semi-trailer axles.

[0102] In the embodiments of the present application, the minimum wheel slip rate corresponding to each axle of the vehicle is taken as the target, a target function can be constructed, and by setting the wheel slip rates corresponding to each axle to be different and in accordance with the preset locking sequence of each axle, the vehicle can be prevented from losing stability under extreme conditions and the stability of the vehicle can be improved. By setting the wheel slip rates of each axle, the longitudinal adhesion coefficients of each axle are determined, the longitudinal adhesion coefficients of each axle determine the braking force distribution results corresponding to each axle, and the sum of the braking force distribution results of each axle is equal to the total adhesion force under the target braking intensity, so that the vehicle is in a stable state whether it is stationary or moving at a constant speed. By using the longitudinal adhesion coefficients, the braking force distribution results of each axle can be adjusted based on the wheel slip rates of each axle, and the braking force can be reasonably distributed to each axle. It can be seen that, under the constraint of the target constraint condition, the target function is solved to obtain the minimum wheel slip rate corresponding to each axle and the braking force distribution results in the state of the minimum overall slip rate, so that the braking force distribution results corresponding to each axle are more reasonable, and the stability and safety of the vehicle can be improved.

[0103] To improve the stability and safety of the semi-trailer train, a straight-line braking force distribution strategy is designed: the semi-trailer train generates the maximum braking deceleration to shorten the braking distance, the weight coefficient of the wheel slip rate is used to control the locking sequence of each axle of the tractor and the semi-trailer, and the wheel slip rate of each axle is controlled to remain at a small level.

[0104] Therefore, the braking force distribution strategy of the semi-trailer train based on the wheel slip rate can be converted into a multivariable nonlinear programming problem with equality and inequality constraints. Specifically:

[0105] The target function is:

[0106]

[0107] The target constraint conditions include:

[0108] λ f =ε m λ m , λ f =ε r λ r

[0109] 0≤λ f ≤1, 0≤λ m ≤1, 0≤λ r ≤1

[0110] F xf +F xm +F xr =(W1+W2)z

[0111]

[0112] F Hx =W2z-F xr

[0113] Among them, λ f =ε m λ m and λ f =ε r λ r Used to express the weight coefficient based on the tractor's rear axle and the semi-trailer's axle, controlling the locking order of the tractor's front axle, the tractor's rear axle and the semi-trailer's axle; 0≤λ f ≤1, 0≤λ m ≤1 and 0≤λ r ≤1 is used to represent the range of wheel slip rates of the tractor's front axle, tractor's rear axle, and semi-trailer's axle; F xf +F xm +F xr =(W1+W2)z is used to indicate that the sum of the braking force distribution results of the tractor front axle, the tractor rear axle and the semi-trailer axle is equal to the total adhesion corresponding to the target braking intensity; as well as It is used to indicate the braking force distribution result of each axle based on the longitudinal adhesion coefficient and vertical force of each axle; F Hx =W2z-F xr Used to indicate the longitudinal force balance at the saddle.

[0114] Based on the above-mentioned objective function and objective constraints, using tools or algorithms for solving the minimum problem of constrained nonlinear multivariable functions, the minimum wheel slip rate of the tractor's front axle, tractor's rear axle and semi-trailer axle, as well as the braking force distribution results of the tractor's front axle, tractor's rear axle and semi-trailer axle under the target braking intensity can be solved.

[0115] For ease of understanding, the following describes the process of determining the vehicle braking force of the present application by taking the determination of the braking force of a semi-trailer vehicle train as an example. Figure 3 This is a flow chart of a method for determining the braking force of a semi-trailer vehicle train provided in an embodiment of the present application. The method for determining the braking force of a semi-trailer vehicle train includes steps S301 to S305.

[0116] In step S301, the vertical forces of the tractor front axle, tractor rear axle, semi-trailer axle and saddle are obtained by simultaneously solving the constructed vertical force balance equation of the tractor, the moment balance equation of the tractor, the vertical force balance equation of the semi-trailer and the moment balance equation of the saddle.

[0117] In step S302, the longitudinal adhesion coefficients of the tractor front axle, the tractor rear axle and the semitrailer axle are determined based on the Burckhardt tire model and the vehicle slip ratios of the tractor front axle, the tractor rear axle and the semitrailer axle.

[0118] In step S303, a multi-element objective function about the wheel slip ratios of the tractor front axle, the tractor rear axle and the semitrailer axle is constructed. The objective function can be expressed as:

[0119]

[0120] In step S304, the equation constraints and inequality constraints about the wheel slip ratios of the tractor front axle, the tractor rear axle and the semitrailer axle and the braking force distribution results are set, and the equation constraints about the longitudinal force balance of the saddle are set, so as to obtain the objective constraints. Specifically:

[0121] λ f = ε m λ m , λ f = ε r λ r

[0122] 0≤ λ f ≤1, 0≤ λ m ≤1, 0≤ λ r ≤1

[0123] F xf +F xm +F xr =(W1+W2)z

[0124]

[0125] F Hx =W2z-F xr

[0126] In step S305, the minimum wheel slip ratio, vertical force, longitudinal adhesion coefficient and braking force distribution result of the tractor front axle, the tractor rear axle and the semitrailer axle under the target braking intensity are solved by using a tool or algorithm for solving the minimum value problem of a constrained nonlinear multivariate function.

[0127] Optionally, the tool or algorithm for solving the minimum value problem of a constrained nonlinear multivariate function can be the fmincon function.

[0128] Returning to step S301, the minimum wheel slip ratio, vertical force, longitudinal adhesion coefficient and braking force distribution result of the tractor front axle, the tractor rear axle and the semitrailer axle under the target braking intensity of the next step are calculated.

[0129] Take dry asphalt pavement as an example, Figure 4a 、 Figure 4b 、 Figure 4c as well as Figure 4d As shown, the minimum wheel slip rate, vertical force, longitudinal adhesion coefficient and braking force distribution results of the tractor front axle, tractor rear axle and semi-trailer axle are calculated respectively.

[0130] like Figure 4a As shown in the figure, the vertical forces on the front axle, rear axle and semi-trailer axle of the tractor under different target braking intensities. As the target braking intensity increases, the braking force on the front axle of the tractor gradually increases, and the braking force on the rear axle of the tractor also gradually increases. However, the increasing trend of the braking force on the rear axle of the tractor is smaller than the increasing trend of the braking force on the front axle of the tractor.

[0131] like Figure 4b As shown in the figure, the minimum wheel slip ratios of the tractor front axle, tractor rear axle and semi-trailer axle under different target braking intensities are small. Figure 4b Difficult to distinguish. Figure 4c This is a partial enlarged view of the minimum wheel slip rate of the tractor front axle, tractor rear axle and semi-trailer axle under different target braking intensities. Figure 4c It can be seen that as the target braking intensity gradually increases, the minimum wheel slip rates of the tractor's front axle, the tractor's rear axle, and the semi-trailer's axle all increase continuously. Furthermore, as the target braking intensity gradually increases, the minimum wheel slip rate of the tractor's front axle reaches its maximum, while the minimum wheel slip rate of the semi-trailer's axle is smaller than the minimum wheel slip rate of the tractor's front axle, but larger than the minimum wheel slip rate of the tractor's rear axle. In other words, the wheel slip rate weight coefficients can be used to control the wheel slip rates of the tractor's front axle, the tractor's rear axle, and the semi-trailer's axle, further ensuring the locking order of the tractor's front axle, the tractor's rear axle, and the semi-trailer's axle, and improving the braking directional stability of the semi-trailer train.

[0132] like Figure 4d The figure shows the braking force distribution results for the tractor's front axle, rear axle, and semi-trailer axle under different target braking intensities. As the target braking intensity increases, the braking force distribution results for the tractor's front axle, rear axle, and semi-trailer axle also gradually increase. The braking force distribution result for the semi-trailer axle is the largest, while the braking force distribution result for the tractor's rear axle is smaller than that for the semi-trailer axle and larger than that for the tractor's front axle.

[0133] Based on the same inventive concept, the embodiment of the present application also provides a device for determining the braking force of a vehicle. Figure 5 The vehicle braking force determination device provided by the embodiment of the present application is described in detail.

[0134] Figure 5 FIG. 1 is a structural schematic diagram of a vehicle braking force determination device provided by an embodiment of the present application.

[0135] As shown in Figure 5 , the vehicle braking force determination device 500 can include a construction module 510 and a determination module 520.

[0136] The construction module 510 can be configured to construct a target function with the minimum wheel slip ratio of each axle of the vehicle as the target.

[0137] The determination module 520 can be configured to solve the minimum wheel slip ratio of each axle corresponding to the target braking intensity of the target function based on a target constraint condition, and the braking force distribution result corresponding to the minimum wheel slip ratio, wherein the target constraint condition includes that the wheel slip ratios of each axle are different and meet a preset locking sequence of each axle, the wheel slip ratios of each axle determine the longitudinal adhesion coefficients of each axle, the longitudinal adhesion coefficients of each axle determine the braking force distribution result of each axle, and the sum of the braking force distribution result of each axle is equal to the total adhesion force corresponding to the target braking intensity.

[0138] In one embodiment, the determination module can be further configured to set the wheel slip ratio of a target axle equal to the product of the wheel slip ratio of each other axle and the weight coefficient corresponding to each other axle, the target axle is the axle with the maximum wheel slip ratio among the axles, each other axle is an axle other than the target axle among the axles, the weight coefficient is set according to the preset locking sequence, and the weight coefficient is greater than 1.

[0139] In one embodiment, the construction module can be further configured to construct the target function based on the sum of the squares of the wheel slip ratios of each axle.

[0140] In one embodiment, the vehicle includes a tractor and at least one semitrailer, the tractor and the at least one semitrailer are connected through a saddle, each axle includes a tractor front axle, a tractor rear axle, and at least one semitrailer axle; the construction module can be further configured to construct wherein J(λ f ,λ m ,λ r ) is used to represent the target function, λ f is used to represent the wheel slip ratio of the tractor front axle, λ m is used to represent the wheel slip ratio of the tractor rear axle, and λ r is used to represent the wheel slip ratio of the semitrailer axle.

[0141] In one embodiment, the determination module can be further configured to solve the minimum wheel slip ratio of each axle corresponding to the target braking intensity of the target function based on λf =ε m λ m and λ f =ε r λ r , so that the wheel slip rates corresponding to each axle are different and conform to the preset locking order of each axle, ε m Used to represent the weight coefficient corresponding to the rear axle of the tractor, ε r Used to represent the weight coefficient corresponding to the semi-trailer axle, ε m >1,ε r >1 and ε m >ε r .

[0142] In one embodiment, the determination module can also be used to determine the Hx =W2z-F xr , so that the longitudinal force at the saddle is balanced, where F Hx is the longitudinal force transmitted from the tractor to the semi-trailer by the saddle, W2 is the weight of the semi-trailer, z is the braking strength, F xr The braking force distribution results for the semi-trailer axles.

[0143] In one embodiment, the determination module can also be used based on The longitudinal adhesion coefficient corresponding to the front axle of the tractor determines the braking force distribution result corresponding to the front axle of the tractor, F xf Used to indicate the braking force distribution result of the tractor's front axle. Used to express the longitudinal adhesion coefficient of the front axle of the tractor, F zf Used to represent the vertical force on the front axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the rear axle of the tractor determines the braking force distribution result corresponding to the rear axle of the tractor, F xm Used to indicate the braking force distribution result of the tractor's rear axle. Used to express the longitudinal adhesion coefficient of the tractor's rear axle, F zm is the vertical force on the rear axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the semi-trailer axle determines the braking force distribution result corresponding to the semi-trailer axle, F xr is the braking force distribution result of the semi-trailer axle, Used to express the longitudinal adhesion coefficient of the semi-trailer axle, F zr Used to represent the vertical force on the axle of a semi-trailer.

[0144] In one embodiment, the determination module can also be used to construct the vertical force balance equation and the torque balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the vertical moment balance equation of the saddle; the vertical force balance equation and the torque balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the vertical moment balance equation of the saddle are solved simultaneously to obtain the vertical force of the tractor's front axle, the vertical force of the tractor's rear axle, and the vertical force of the semi-trailer's axle.

[0145] In one embodiment, the determination module can also be used based on The wheel slip rate of the tractor's front axle determines the longitudinal adhesion coefficient corresponding to the tractor's front axle. Used to express the longitudinal adhesion coefficient of the tractor's front axle; based on The wheel slip rate of the tractor's rear axle determines the longitudinal adhesion coefficient corresponding to the tractor's rear axle. Used to express the longitudinal adhesion coefficient of the tractor's rear axle; based on The wheel slip rate of the semi-trailer axle determines the longitudinal adhesion coefficient corresponding to the semi-trailer axle. Used to represent the longitudinal adhesion coefficient of the semi-trailer axle; where c1, c2, and c3 are fitting parameters.

[0146] Figure 6 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application is shown.

[0147] The electronic device may include a processor 601 and a memory 302 storing computer program instructions.

[0148] Specifically, the processor 601 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiments of the present application.

[0149] The memory 602 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 602 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive, or a combination of two or more of these. Where appropriate, the memory 602 may include removable or non-removable (or fixed) media. Where appropriate, the memory 602 may be inside or outside the integrated gateway disaster recovery device. In a specific embodiment, the memory 602 is a non-volatile solid-state memory.

[0150] The memory can include read-only memory (ROM), random-access memory (RAM), magnetic disk storage mediums devices, optical storage mediums devices, flash memory devices, electrical, optical, or other physical / tangible memory storage devices. Thus, generally, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software that, when executed (by one or more processors), is operable to perform operations described with reference to the methods according to an aspect of the present disclosure.

[0151] The processor 601 implements the vehicle braking force determination method of any of the above-described embodiments by reading and executing computer program instructions stored in the memory 602.

[0152] In one example, the electronic device can further include a communication interface 603 and a bus 610. As shown, the processor 601, the memory 602, and the communication interface 603 are connected through the bus 610 and complete communication with each other. Figure 6

[0153] The communication interface 603 is mainly used to realize the communication between the modules, devices, units and / or equipment in the embodiments of the present application.

[0154] The bus 610 includes components of hardware, software, or both that couple to each other in a functional manner. By way of example and not limitation, the bus can include an accelerated graphics port (AGP) or other graphics bus, an enhanced industry standard architecture (EISA) bus, a front-side bus (FSB), a hypertransport (HT) interconnect, an industry standard architecture (ISA) bus, an infiniband interconnect, a low pin count (LPC) bus, a memory bus, a microchannel architecture (MCA) bus, a peripheral component interconnect (PCI) bus, a PCI-Express (PCI-X) bus, a serial advanced technology attachment (SATA) bus, a video electronics standards association local (VLB) bus, or other suitable bus or combination of two or more of these. Where appropriate, the bus 610 can include one or more buses. Although the present embodiments describe and show a particular bus, the present application contemplates any suitable bus or interconnect.

[0155] The electronic device can perform the vehicle braking force determination method in the embodiments of the present application based on the objective function and the objective constraint condition, thereby realizing Figure 1 the described vehicle braking force determination method.

[0156] ​In addition, in combination with the method for determining vehicle braking force in the above embodiments, the embodiments of the present application can provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; the computer program instructions are executed by a processor to implement any of the above-described methods for determining vehicle braking force.

[0157] The embodiments of the present application also provide a computer program product, comprising a computer program, which is executed by a processor to implement any of the above-described methods for determining vehicle braking force.

[0158] It should be noted that the present application is not limited to the specific configurations and processes described above and shown in the drawings. For the sake of brevity, detailed descriptions of well-known methods are omitted. In the above embodiments, several specific steps are described and shown as examples. However, the method processes of the present application are not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order of the steps, after understanding the spirit of the present application.

[0159] The functional blocks shown in the above-described structural block diagrams can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a functional card, etc. When implemented in software, the elements of the present application are program or code segments used to perform the required tasks. The program or code segments can be stored in a machine-readable medium or transmitted through a data signal carried in a carrier wave over a transmission medium or communication link. The "machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROM, flash memory, erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segments can be downloaded via a computer network such as the Internet, an intranet, etc.

[0160] It should also be noted that the exemplary embodiments mentioned in the present application describe some methods or systems based on a series of steps or devices. However, the present application is not limited to the order of the above steps, that is, the steps can be executed in the order mentioned in the embodiments, or in an order different from the embodiments, or several steps can be executed simultaneously.

[0161] The computer program instructions can also be loaded onto a computer, other programmable data processing apparatus, or other processing device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other processing device to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide processes for implementing the functions / acts specified in the flowchart and / or block diagram block or blocks.

[0162] The above only is a specific implementation of the present application, and those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the above-described system, module and unit can refer to the corresponding process in the foregoing method embodiments, which will not be described herein. It should be understood that the protection scope of the present application is not limited to this, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical range disclosed in the present application, and these modifications or replacements shall be covered within the protection scope of the present application.

Claims

1. A method for determining vehicle braking force, characterized in that: include: The objective function is constructed with the goal of minimizing the wheel slip rate corresponding to each axle of the vehicle; Based on the target constraints, the objective function is solved for the minimum wheel slip rate corresponding to each axle under the target braking intensity, and the braking force distribution result corresponding to the minimum wheel slip rate, wherein the target constraints include: the wheel slip rates corresponding to the axles are different and comply with the preset locking order of the axles, the wheel slip rates of the axles determine the longitudinal adhesion coefficients corresponding to the axles, the longitudinal adhesion coefficients corresponding to the axles determine the braking force distribution results corresponding to the axles, and the sum of the braking force distribution results corresponding to the axles is equal to the total adhesion corresponding to the target braking intensity.

2. The method according to claim 1, characterized in that The wheel slip rates corresponding to the axles are different and comply with a preset locking order of the axles, including: The wheel slip rate of the target axle is equal to the product of the wheel slip rate of each other axle and the weight coefficient corresponding to each other axle. The target axle is the axle with the largest wheel slip rate among the axles, and each other axle is the axle among the axles other than the target axle. The weight coefficient is set according to the preset locking order, and the weight coefficient is greater than 1.

3. The method according to claim 1, characterized in that With the goal of minimizing the wheel slip rate corresponding to each axle of the vehicle, an objective function is constructed, including: The objective function is constructed based on the sum of squares of the wheel slip rates corresponding to the axles.

4. The method according to claim 3, characterized in that The vehicle includes a tractor and at least one semi-trailer, the tractor and the at least one semi-trailer are connected via a saddle, and the axles include a tractor front axle, a tractor rear axle and at least one semi-trailer axle; With the goal of minimizing the wheel slip rate corresponding to each axle of the vehicle, an objective function is constructed, including: Build Among them, J(λ f ,λ m ,λ r ) is used to represent the objective function, λ f Used to represent the wheel slip rate of the front axle of the tractor, λ m Used to represent the wheel slip rate of the rear axle of the tractor, λ r Used to represent the wheel slip rate of the semi-trailer axle.

5. The method according to claim 4, characterized in that The wheel slip rates corresponding to the axles are different and comply with a preset locking order of the axles, including: Based on λ f =ε m λ m and λ f =ε r λ r , so that the wheel slip rates corresponding to the axles are different and conform to the preset locking order of the axles, ε m Used to represent the weight coefficient corresponding to the rear axle of the tractor, ε r Used to represent the weight coefficient corresponding to the semi-trailer axle, ε m >1,ε r >1 and ε m >ε r .

6. The method according to claim 4, characterized in that The target constraints also include: Based on F Hx =W2z-F xr , so that the longitudinal force at the saddle is balanced, where F Hx is the longitudinal force transmitted from the tractor to the semi-trailer by the saddle, W2 is the weight of the semi-trailer, z is the braking strength, F xr The braking force distribution result of the semi-trailer axle.

7. The method according to claim 4, characterized in that The longitudinal adhesion coefficient corresponding to each axle determines the braking force distribution result corresponding to each axle, including: based on The longitudinal adhesion coefficient corresponding to the front axle of the tractor determines the braking force distribution result corresponding to the front axle of the tractor, F xf Used to indicate the braking force distribution result of the front axle of the tractor, Used to express the longitudinal adhesion coefficient of the front axle of the tractor, F zf Used to represent the vertical force on the front axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the rear axle of the tractor determines the braking force distribution result corresponding to the rear axle of the tractor, F xm It is used to indicate the braking force distribution result of the rear axle of the tractor. Used to express the longitudinal adhesion coefficient of the rear axle of the tractor, F zm is the vertical force on the rear axle of the tractor; based on The longitudinal adhesion coefficient corresponding to the semi-trailer axle determines the braking force distribution result corresponding to the semi-trailer axle, F xr is the braking force distribution result of the semi-trailer axle, Used to express the longitudinal adhesion coefficient of the semi-trailer axle, F zr Used to represent the vertical force on the semi-trailer axle.

8. The method according to claim 7, characterized in that The process of determining the vertical force of the front axle of the tractor, the vertical force of the rear axle of the tractor, and the vertical force of the axle of the semi-trailer includes: Constructing a vertical force balance equation and a moment balance equation of the tractor, a vertical force balance equation of the semi-trailer, and a vertical moment balance equation of the saddle; The vertical force balance equation and moment balance equation of the tractor, the vertical force balance equation of the semi-trailer, and the vertical moment balance equation of the saddle are solved simultaneously to obtain the vertical force of the front axle of the tractor, the vertical force of the rear axle of the tractor, and the vertical force of the axle of the semi-trailer.

9. The method according to any one of claims 4 to 8, characterized in that The wheel slip ratio of each axle determines the longitudinal adhesion coefficient corresponding to each axle, including: based on The wheel slip rate of the front axle of the tractor determines the longitudinal adhesion coefficient corresponding to the front axle of the tractor, Used to express the longitudinal adhesion coefficient of the front axle of the tractor; based on The wheel slip rate of the rear axle of the tractor determines the longitudinal adhesion coefficient corresponding to the rear axle of the tractor, Used to express the longitudinal adhesion coefficient of the rear axle of the tractor; based on The wheel slip rate of the semi-trailer axle determines the longitudinal adhesion coefficient corresponding to the semi-trailer axle, Used to express the longitudinal adhesion coefficient of the semi-trailer axle; Among them, c1, c2 and c3 are fitting parameters.

10. A device for determining vehicle braking force, characterized in that: include: A construction module is used to construct an objective function with the goal of minimizing the wheel slip rate corresponding to each axle of the vehicle; A determination module is configured to solve the objective function for the minimum wheel slip rate corresponding to each axle under the target braking intensity, and the braking force distribution result corresponding to the minimum wheel slip rate, based on target constraints, wherein the target constraints include: the wheel slip rates corresponding to each axle are different and comply with a preset locking order of each axle; the wheel slip rates of each axle determine the longitudinal adhesion coefficient corresponding to each axle; the longitudinal adhesion coefficient corresponding to each axle determines the braking force distribution result corresponding to each axle; and the sum of the braking force distribution results corresponding to each axle is equal to the total adhesion corresponding to the target braking intensity.

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