Braking anti-lock method and system of distributed electric drive vehicle

Abstract

The invention discloses a braking anti-lock method and system for a distributed electric drive vehicle, and belongs to the technical field of vehicle braking anti-lock control. The method comprises the following steps: constructing a two-dimensional mapping table; the real-time vehicle longitudinal speed and the brake pedal opening degree of the distributed electric drive vehicle are obtained, and the ideal braking time of the vehicle longitudinal speed and the brake pedal opening degree under the current time step is obtained in combination with the two-dimensional mapping table; on the basis of the obtained ideal braking time, an ideal braking curve is generated through quartic polynomial fitting; based on the ideal braking curve, the difference value delta vi between the current longitudinal speed of the vehicle and the ideal braking curve is calculated, the deviation condition of the current speed and the speed under the ideal braking condition is evaluated, the braking force is dynamically adjusted, the braking force output of each wheel is dynamically adjusted, wheel locking can be effectively prevented under different complex road conditions, and the service life of the vehicle is prolonged. The braking performance and the driving stability of the vehicle are ensured, and technical guarantee is provided for safety application of the distributed electric drive vehicle.

Description

Technical Field

[0001] The invention belongs to the technical field of vehicle anti-lock braking control, and in particular relates to an anti-lock braking method and system for a distributed electric drive vehicle. Background Art

[0002] With the rapid development of electric vehicle technology and the increasing popularity of autonomous driving technology, the braking control and safety requirements of vehicles have been significantly improved. In actual driving, especially in complex environments such as emergency braking or slippery roads, vehicles are prone to wheel locking, resulting in loss of control and causing safety hazards. Traditional anti-lock braking systems (ABS) prevent wheel locking by monitoring wheel speed and adjusting braking force, thereby improving braking performance and improving vehicle stability. However, as electric vehicles gradually adopt distributed electric drive systems, the limitations of traditional ABS in dealing with multi-motor drive systems are gradually exposed.

[0003] Distributed electric drive vehicles have the advantage of independently controlling each wheel, which makes it possible to have more precise braking control. However, existing ABS technology is mainly based on a single motor drive mode, which makes it difficult to fully utilize the flexibility of the distributed system and cannot respond to complex and changing driving conditions in real time. Therefore, the application effect of existing anti-lock braking strategies in multi-motor drive systems is relatively limited, especially in high-speed dynamic driving environments, where traditional ABS cannot provide sufficient stability and safety.

[0004] In order to solve these problems, the present invention proposes a novel anti-lock braking strategy for a distributed electric drive vehicle. Summary of the invention

[0005] In view of the deficiencies in the prior art, an object of the present invention is to provide an anti-lock braking method and system for a distributed electric drive vehicle, which solves the problems in the prior art.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A distributed electric drive vehicle anti-lock braking method comprises the following steps:

[0008] Construct a two-dimensional mapping table through historical data statistics and analysis;

[0009] Based on the two-dimensional table mapping, the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle are obtained, and combined with the two-dimensional mapping table, the ideal braking time of the vehicle longitudinal speed and brake pedal opening at the current time step is obtained;

[0010] Based on the obtained ideal braking time, an ideal braking curve is generated by fitting a fourth-order polynomial;

[0011] Based on the ideal braking curve, calculate the difference Δv between the current vehicle longitudinal speed and the ideal braking curve i , evaluates the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjusts the braking force.

[0012] Furthermore, the mapping function in the two-dimensional mapping table is:

[0013] t=f(v,σ)

[0014] Wherein, v represents the longitudinal speed of the vehicle, σ represents the brake pedal opening, and t represents the braking time required for the vehicle under ideal conditions.

[0015] Furthermore, the process of constructing the two-dimensional mapping table is:

[0016] S11, discretize the longitudinal speed v of the vehicle into a sampling space with an initial value of 0 m / s, a final value of 40 m / s, and a sampling interval of 2 m / s;

[0017] S12, discretize the brake pedal opening σ into a sampling space with an initial value of 0°, a final value of 30°, and a sampling interval of 1°, and construct a two-dimensional table with a size of 21×31; obtain the braking time of each cell in the two-dimensional table in the real scene, so as to obtain the two-dimensional table mapping of the function t=f(v,σ).

[0018] Furthermore, when generating the ideal braking curve, the current acceleration a is assumed to be i = 0, at the current vehicle longitudinal speed v i , ideal braking time t i Down, to the braking end speed v e =0, acceleration a e =0, the function of the ideal braking curve is: v πi =π(t).

[0019] Furthermore, the quartic polynomial function is:

[0020]

[0021] Where b1 is the current vehicle speed v i , b2 is the current acceleration a i , b3 and b4 are coefficients.

[0022] Furthermore, the solution process of coefficients b3 and b4 is: let the matrix Solve the linear equation system Ax = c, solution is a vector of length 2, and the elements in the vector correspond to the coefficients b3 and b4 in the quartic polynomial.

[0023] Furthermore, the process of dynamically adjusting the braking force includes:

[0024] S41, constructing a speed-pressure characteristic curve to reflect the corresponding relationship between the speed change and the required pressure value;

[0025] S42, when it is determined that Δv i ≥0, the strategy for applying braking force is: solve the corresponding Δv through the speed pressure characteristic curve i Required pressure value ΔF i And output to the brake system;

[0026] S43, when it is determined that Δv i When ≤0, the strategy for withdrawing the braking force is: correct the braking force to 0.98 times the current braking force and output it to the braking system.

[0027] A distributed electric drive vehicle anti-lock braking system, comprising:

[0028] Two-dimensional mapping table construction module: construct a two-dimensional mapping table through historical data statistics and analysis;

[0029] Ideal braking time calculation module: Based on the two-dimensional table mapping, the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle are obtained, and combined with the two-dimensional mapping table, the ideal braking time of the vehicle longitudinal speed and brake pedal opening at the current time step is obtained;

[0030] Ideal braking curve generation module: based on the ideal braking time obtained, the ideal braking curve is generated through fourth-order polynomial fitting;

[0031] And, a braking adjustment module: based on the ideal braking curve, calculates the difference Δv between the current vehicle longitudinal speed and the ideal braking curve i , evaluates the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjusts the braking force.

[0032] A computer storage medium stores a readable program, which can execute the above-mentioned anti-lock braking method for a distributed electric drive vehicle when the program is running.

[0033] An electronic device, comprising: a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus;

[0034] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute operations corresponding to the above-mentioned anti-lock braking method for a distributed electric drive vehicle.

[0035] Beneficial effects of the present invention:

[0036] 1. The present invention constructs a two-dimensional table mapping between vehicle speed and brake pedal opening through historical data, calculates the ideal braking time, and generates an ideal braking curve in combination with polynomial fitting; by real-time monitoring of the vehicle status and comparing the current vehicle speed with the ideal braking curve, the braking force output of each wheel is dynamically adjusted; thereby effectively preventing wheel locking under different complex road conditions, ensuring the vehicle's braking performance and driving stability, and providing technical guarantee for the safe application of distributed electric drive vehicles.

[0037] 2. The present invention automatically adjusts the size of the braking force to ensure the braking effect under different road conditions and environments, enhances the safety and adaptability of distributed electric drive vehicles, and provides a solid guarantee for driving safety in complex dynamic environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0039] Figure 1 It is a flow chart of the anti-lock braking method of the distributed electric drive vehicle of the present invention;

[0040] Figure 2 It is a two-dimensional mapping representation diagram constructed by the present invention;

[0041] Figure 3 It is a schematic diagram of dynamic braking force adjustment of the present invention. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] A distributed electric drive vehicle anti-lock braking method comprises the following steps:

[0045] S1, construct a two-dimensional mapping table through historical data statistics and analysis;

[0046] The mapping function in the two-dimensional mapping table is:

[0047] t=f(v,σ)

[0048] Among them, v represents the longitudinal speed of the vehicle, σ represents the brake pedal opening, and t represents the braking time required for the vehicle under ideal conditions. After completing the construction of the two-dimensional mapping table, the braking time required for the vehicle under any v, σ can be estimated by interpolation and other strategies;

[0049] like Figure 2 As shown, the process of constructing a two-dimensional mapping table is:

[0050] S11, discretize the longitudinal speed v of the vehicle into a sampling space with an initial value of 0 m / s, a final value of 40 m / s, and a sampling interval of 2 m / s;

[0051] S12, discretize the brake pedal opening σ into a sampling space with an initial value of 0°, a final value of 30°, and a sampling interval of 1°, and construct a two-dimensional table of size 21×31; obtain the braking time of each cell in the two-dimensional table in a real scenario, so as to obtain the two-dimensional table mapping of the function t=f(v,σ); since the sampling space is dense enough, the braking time required for the vehicle under any v,σ can be estimated by interpolation.

[0052] S2, based on the two-dimensional table mapping constructed in S1, obtains the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle, and combines the two-dimensional mapping table constructed in S1 to obtain the vehicle longitudinal speed v at the current time step i i and brake pedal opening σ i The ideal braking time t i .

[0053] S3, based on the ideal braking time obtained in S2, an ideal braking curve is generated by fitting a fourth-order polynomial;

[0054] When generating the ideal braking curve, assume that the current acceleration a i = 0, at the current vehicle longitudinal speed v i , ideal braking time t i Down, to the braking end speed v e =0, acceleration a e =0, the function of the ideal braking curve is: v πi =π(t);

[0055] The fourth-order polynomial is used to fit the ideal braking curve to solve the speed of the vehicle at any time under ideal braking conditions. The fourth-order polynomial function is as follows:

[0056]

[0057] Where b1 is the current vehicle speed v i , b2 is the current acceleration a i , coefficients b3 and b4 are solved by the following strategy:

[0058] Let the matrix Solve the linear equation system Ax = c, solution is a vector of length 2, the elements in the vector correspond to the coefficients b3 and b4 in the quartic polynomial;

[0059] S4, based on the ideal braking curve obtained in S3, calculate the current vehicle longitudinal speed v i Compared with the ideal braking curve v πi The difference Δv i , evaluate the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjust the braking force;

[0060] If the judgment condition Δv i ≥0, indicating that the current vehicle speed is greater than the current speed under ideal braking conditions, and the braking force is applied to keep the vehicle braking; if Δv i ≤0, indicating that the current vehicle speed is lower than the current speed under ideal braking conditions, and the braking force is reduced to prevent the vehicle from locking. The above anti-lock control simulation process code can be constructed in SIMULINK, and the code can be written into the real vehicle controller after simulation testing to realize the anti-lock braking of the distributed electric drive vehicle.

[0061] like Figure 3 As shown, the process of dynamically adjusting the braking force includes:

[0062] S41, constructing a speed-pressure characteristic curve through prior knowledge to construct a corresponding relationship between the speed change magnitude and the required pressure value, thereby solving the pressure magnitude required by the vehicle when the speed changes;

[0063] S42, when it is determined that Δv i ≥0, the strategy for applying braking force is: solve the corresponding Δv through the speed pressure characteristic curve i Required pressure value ΔF i And output to the brake system;

[0064] S43, when it is determined that Δv i When ≤0, the strategy for withdrawing the braking force is: correct the braking force to 0.98 times the current braking force and output it to the braking system.

[0065] Through the above steps, the ideal speed of the vehicle at the current time step when braking under ideal braking conditions can be repeatedly solved, the actual vehicle speed is subtracted from the ideal speed and the braking force is dynamically compensated based on this to ensure that the current vehicle speed does not deviate excessively from the ideal braking speed curve.

[0066] Based on similar inventive concepts, an embodiment of the present invention further provides a computer storage medium storing a readable program, which can execute the above-mentioned anti-lock braking method for a distributed electric drive vehicle when the program is running.

[0067] Based on similar inventive concepts, an embodiment of the present invention provides an electronic device, comprising: a processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other through the communication bus;

[0068] The memory is used to store at least one executable instruction, and the executable instruction enables the processor to execute operations corresponding to the above-mentioned anti-lock braking method for a distributed electric drive vehicle.

[0069] Example 2

[0070] In this embodiment, a distributed electric drive vehicle anti-lock braking system is proposed, which specifically includes:

[0071] Two-dimensional mapping table construction module: construct a two-dimensional mapping table through historical data statistics and analysis;

[0072] Ideal braking time calculation module: Based on the two-dimensional table mapping, the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle are obtained, and combined with the two-dimensional mapping table, the ideal braking time of the vehicle longitudinal speed and brake pedal opening at the current time step is obtained;

[0073] Ideal braking curve generation module: based on the ideal braking time obtained, the ideal braking curve is generated through fourth-order polynomial fitting;

[0074] And, a braking adjustment module: based on the ideal braking curve, calculates the difference Δv between the current vehicle longitudinal speed and the ideal braking curve i , evaluates the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjusts the braking force.

[0075] The method of the present invention may be implemented in hardware, firmware, or as software or computer code that may be stored in a recording medium (such as a CDROM, RAM, floppy disk, hard disk, or magneto-optical disk), or as computer code that is originally stored in a remote recording medium or a non-temporary machine-readable medium downloaded over a network and will be stored in a local recording medium, so that the method described herein may be stored in such software processing on a recording medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware (such as an ASIC or FPGA). It is understood that a computer, processor, microprocessor controller, or programmable hardware includes a storage component (e.g., RAM, ROM, flash memory, etc.) that can store or receive software or computer code, and when the software or computer code is accessed and executed by a computer, processor, or hardware, the method described herein is implemented. In addition, when a general-purpose computer accesses the code for implementing the method shown herein, the execution of the code converts the general-purpose computer into a dedicated computer for executing the method shown herein.

[0076] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A distributed electric drive vehicle anti-lock braking method, characterized in that: The following steps are involved: Construct a two-dimensional mapping table through historical data statistics and analysis; Based on the two-dimensional table mapping, the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle are obtained, and combined with the two-dimensional mapping table, the ideal braking time of the vehicle longitudinal speed and brake pedal opening at the current time step is obtained; Based on the obtained ideal braking time, an ideal braking curve is generated by fitting a fourth-order polynomial; Based on the ideal braking curve, calculate the difference Δv between the current vehicle longitudinal speed and the ideal braking curve i , evaluates the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjusts the braking force.

2. The anti-lock braking method for a distributed electric drive vehicle according to claim 1, characterized in that: The mapping function in the two-dimensional mapping table is: t=f(v,σ) Wherein, v represents the longitudinal speed of the vehicle, σ represents the brake pedal opening, and t represents the braking time required for the vehicle under ideal conditions.

3. The anti-lock braking method for a distributed electric drive vehicle according to claim 2, characterized in that: The process of constructing the two-dimensional mapping table is: S11, discretize the longitudinal speed v of the vehicle into a sampling space with an initial value of 0 m / s, a final value of 40 m / s, and a sampling interval of 2 m / s; S12, discretize the brake pedal opening σ into a sampling space with an initial value of 0°, a final value of 30°, and a sampling interval of 1°, and construct a two-dimensional table with a size of 21×31; obtain the braking time of each cell in the two-dimensional table in a real scenario, so as to obtain a two-dimensional table mapping of the function t=f(v,σ).

4. The anti-lock braking method for a distributed electric drive vehicle according to claim 1, characterized in that: When generating the ideal braking curve, assume that the current acceleration a i = 0, at the current vehicle longitudinal speed v i , ideal braking time t i Down, to the braking end speed v e =0, acceleration a e =0, the function of the ideal braking curve is: v πi =π(t).

5. The anti-lock braking method for a distributed electric drive vehicle according to claim 4, characterized in that: The quartic polynomial function is: Where b1 is the current vehicle speed v i , b2 is the current acceleration a i , b3 and b4 are coefficients.

6. The anti-lock braking method for a distributed electric drive vehicle according to claim 5, characterized in that: The solution process of coefficients b3 and b4 is: let the matrix Solve the linear equation system Ax = c, solution is a vector of length 2, and the elements in the vector correspond to the coefficients b3 and b4 in the quartic polynomial.

7. The anti-lock braking method for a distributed electric drive vehicle according to claim 1, characterized in that: The process of dynamically adjusting the braking force includes: S41, constructing a speed-pressure characteristic curve to reflect the corresponding relationship between the speed change and the required pressure value; S42, when it is determined that Δv i When ≥0, the strategy for applying braking force is: solve the corresponding Δv through the speed-pressure characteristic curve i Required pressure value ΔF i And output to the brake system; S43, when it is determined that Δv i When ≤0, the strategy for withdrawing the braking force is: correct the braking force to 0.98 times the current braking force and output it to the braking system.

8. A distributed electric drive vehicle anti-lock braking system, characterized in that: include: Two-dimensional mapping table construction module: construct a two-dimensional mapping table through historical data statistics and analysis; Ideal braking time calculation module: Based on the two-dimensional table mapping, the real-time vehicle longitudinal speed and brake pedal opening of the distributed electric drive vehicle are obtained, and combined with the two-dimensional mapping table, the ideal braking time of the vehicle longitudinal speed and brake pedal opening at the current time step is obtained; Ideal braking curve generation module: based on the ideal braking time obtained, the ideal braking curve is generated through fourth-order polynomial fitting; And, a braking adjustment module: based on the ideal braking curve, calculates the difference Δv between the current vehicle longitudinal speed and the ideal braking curve i , evaluates the deviation between the current speed and the speed under ideal braking conditions, and dynamically adjusts the braking force.

9. A computer storage medium storing a readable program, characterized in that: When the program is running, it can execute the anti-lock braking method for a distributed electric drive vehicle as described in any one of claims 1 to 7.

10. An electronic device, characterized in that: include: A processor, a memory, a communication interface and a communication bus, wherein the processor, the memory and the communication interface communicate with each other via the communication bus; The memory is used to store at least one executable instruction, and the executable instruction enables the processor to perform operations corresponding to the anti-lock braking method for a distributed electric drive vehicle as described in any one of claims 1-7.

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