A method and device for estimating reference vehicle speed under slope braking conditions

Abstract

This application provides a method and apparatus for estimating reference vehicle speed under slope braking conditions. The method includes: acquiring the actual wheel speed of the target vehicle and the acceleration detection value from the vehicle acceleration sensor; determining the wheel adhesion state of the target vehicle based on the actual wheel speed; determining the estimated wheel speed of the target vehicle based on the wheel adhesion state; estimating the initial value of the reference vehicle speed based on the estimated wheel speed and the wheel adhesion state; calculating the estimation error based on the initial value of the reference vehicle speed; and calculating the current vehicle body acceleration of the target vehicle based on the estimation error and the acceleration detection value. Therefore, this method and apparatus can estimate the reference vehicle speed under slope conditions, has good applicability, and a small estimation error.

Description

Technical Field

[0001] This application relates to the field of vehicle control technology, and more specifically, to a method and device for estimating reference vehicle speed under hill braking conditions. Background Technology

[0002] Currently, the main methods for calculating reference vehicle speed under braking conditions are the slope method and the Kalman filter method. The slope method utilizes the dynamics of ABS to calculate the slope of wheel speed reduction between the first two braking actions, and uses this to estimate the wheel speed at the next braking action. The Kalman filter method uses a complex vehicle model to perform vehicle dynamics calculations to derive the reference vehicle speed. In practice, it has been found that the slope method cannot estimate the vehicle speed at the instant ABS activation because it requires at least two wheel speed points with adhesion to form the first estimated slope. Furthermore, the slope method has high requirements for estimating wheel stability; errors in wheel stability estimation directly lead to deviations in the calculated slope. The slope method also cannot handle vehicle speed calculations for conditions such as short-term wheel lock-up, braking, and drive switching. The Kalman filter method requires a large amount of vehicle force information, including the actual braking force of each wheel. Therefore, existing methods are not suitable for estimating reference vehicle speed under slope conditions, have poor applicability, and suffer from large estimation errors. Summary of the Invention

[0003] The purpose of this application is to provide a method and apparatus for estimating reference vehicle speed under slope braking conditions, which can estimate reference vehicle speed under slope conditions, has good applicability, and has small estimation error.

[0004] The first aspect of this application provides a method for estimating reference vehicle speed under hill-start braking conditions, including:

[0005] Obtain the actual wheel speed of the target vehicle and the acceleration detection value of the vehicle acceleration sensor;

[0006] The wheel adhesion state of the target vehicle is determined based on the actual wheel speed.

[0007] The estimated wheel speed of the target vehicle is determined based on the wheel adhesion state.

[0008] The initial reference speed of the target vehicle is estimated based on the estimated wheel speed and the wheel adhesion state.

[0009] The estimation error is calculated based on the initial value of the reference vehicle speed;

[0010] The current vehicle acceleration of the target vehicle is calculated based on the estimation error and the acceleration detection value.

[0011] In the above implementation process, this method first obtains the actual wheel speed of the target vehicle and the acceleration detection value from the vehicle acceleration sensor; then, it determines the wheel adhesion state of the target vehicle based on the actual wheel speed; next, it determines the estimated wheel speed of the target vehicle based on the wheel adhesion state; then, it estimates the initial value of the reference vehicle speed based on the estimated wheel speed and the wheel adhesion state; then, it calculates the estimation error based on the initial value of the reference vehicle speed; finally, it calculates the current vehicle body acceleration of the target vehicle based on the estimation error and the acceleration detection value. It can be seen that the current vehicle body acceleration can be used to calculate the estimated wheel speed when the reference vehicle speed is being estimated and the wheel adhesion state is one of wheel instability. Therefore, this method can perform reference vehicle speed estimation under slope conditions, thereby improving applicability and reducing estimation error.

[0012] Further, determining the wheel adhesion state of the target vehicle based on the actual wheel speed includes:

[0013] Calculate wheel acceleration based on the actual wheel speed;

[0014] The wheel adhesion state of the target vehicle is determined based on the wheel acceleration and a preset acceleration boundary threshold; wherein the wheel adhesion state is either a wheel instability state or a wheel non-instability state.

[0015] Further, determining the estimated wheel speed of the target vehicle based on the wheel adhesion state includes:

[0016] When the wheel's attachment state is the wheel's unstable state, the vehicle body acceleration and the wheel speed value at the moment of instability are obtained, and the wheel speed is estimated based on the wheel speed value at the moment of instability and the vehicle body acceleration.

[0017] When the wheel's attachment state is that the wheel is not unstable, the actual wheel speed is determined as the estimated wheel speed.

[0018] Further, estimating the initial reference vehicle speed of the target vehicle based on the estimated wheel speed and the wheel adhesion state includes:

[0019] The number of non-unstable wheels out of the four wheels of the target vehicle is determined based on the wheel attachment state.

[0020] When the number of wheels that are not unstable is 0 or 4, the average value of the estimated wheel speed is calculated to obtain the initial value of the reference vehicle speed.

[0021] When the number of non-unstable wheels is greater than 0 and less than 4, the non-unstable wheels are identified, and the average value of the estimated wheel speed of the non-unstable wheels is calculated to obtain the initial value of the reference vehicle speed.

[0022] Further, the step of calculating the estimation error based on the initial value of the reference vehicle speed includes:

[0023] The maximum value of the actual wheel speed of the four wheels is determined based on the actual wheel speed.

[0024] The normal deviation is calculated based on the initial reference vehicle speed and the maximum value.

[0025] Obtain the average speed of the stabilizing wheels, and calculate the stabilization deviation based on the average speed of the stabilizing wheels and the initial reference speed.

[0026] The estimated error is calculated based on the normal deviation and the stabilization deviation.

[0027] A second aspect of this application provides a reference vehicle speed estimation device for hill-start braking conditions, the reference vehicle speed estimation device for hill-start braking conditions comprising:

[0028] The acquisition unit is used to acquire the actual wheel speed of the target vehicle and the acceleration detection value of the vehicle acceleration sensor;

[0029] The first determining unit is used to determine the wheel adhesion state of the target vehicle based on the actual wheel speed.

[0030] The second determining unit is used to determine the estimated wheel speed of the target vehicle based on the wheel adhesion state.

[0031] An estimation unit is used to estimate an initial reference vehicle speed of the target vehicle based on the estimated wheel speed and the wheel adhesion state.

[0032] The first calculation unit is used to calculate the estimation error based on the initial value of the reference vehicle speed;

[0033] The second calculation unit is used to calculate the current vehicle acceleration of the target vehicle based on the estimation error and the acceleration detection value.

[0034] In the above implementation process, the device can acquire the actual wheel speed of the target vehicle and the acceleration detection value from the vehicle acceleration sensor through the acquisition unit; determine the wheel adhesion state of the target vehicle based on the actual wheel speed through the first determination unit; determine the estimated wheel speed of the target vehicle based on the wheel adhesion state through the second determination unit; estimate the initial reference speed of the target vehicle based on the estimated wheel speed and wheel adhesion state through the estimation unit; calculate the estimation error based on the initial reference speed through the first calculation unit; and calculate the current vehicle body acceleration of the target vehicle based on the estimation error and the acceleration detection value through the second calculation unit. Therefore, this device can estimate the reference speed under slope conditions, improving applicability and reducing estimation errors.

[0035] Further, the first determining unit includes:

[0036] The first calculation subunit is used to calculate the wheel acceleration based on the actual wheel speed.

[0037] The first determining subunit is used to determine the wheel adhesion state of the target vehicle based on the wheel acceleration and a preset acceleration boundary threshold; wherein the wheel adhesion state is either a wheel instability state or a wheel non-instability state.

[0038] Furthermore, the second determining unit is specifically used to acquire the vehicle body acceleration and the wheel speed value at the moment of instability when the wheel attachment state is the wheel instability state, and to calculate and estimate the wheel speed based on the wheel speed value at the moment of instability and the vehicle body acceleration; when the wheel attachment state is the wheel not instability state, the actual wheel speed is determined as the estimated wheel speed.

[0039] Furthermore, the estimation unit includes:

[0040] The second determining subunit is used to determine the number of non-unstable wheels among the four wheels of the target vehicle based on the wheel attachment state.

[0041] The second calculation subunit is used to calculate the average value of the estimated wheel speed when the number of the non-unstable wheels is 0 or 4, so as to obtain the initial value of the reference vehicle speed.

[0042] The second determining subunit is further configured to determine the unstable wheels when the number of unstable wheels is greater than 0 and less than 4, and calculate the average value of the estimated wheel speed of the unstable wheels to obtain the initial value of the reference speed.

[0043] Furthermore, the first computing unit includes:

[0044] The third determining subunit is used to determine the maximum value of the actual wheel speed of the four wheels based on the actual wheel speed;

[0045] The third calculation subunit is used to calculate the normal deviation based on the initial value of the reference vehicle speed and the maximum value;

[0046] The third calculation subunit is also used to obtain the average speed of the stabilizing wheels and calculate the stabilization deviation based on the average speed of the stabilizing wheels and the initial reference speed.

[0047] The third calculation subunit is also used to calculate the estimation error based on the normal deviation and the stabilization deviation.

[0048] A third aspect of this application provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor runs the computer program to cause the electronic device to perform the reference vehicle speed estimation method for ramp braking conditions as described in any one of the first aspects of this application.

[0049] The fourth aspect of this application provides a computer-readable storage medium storing computer program instructions, which, when read and executed by a processor, perform the reference vehicle speed estimation method for the ramp braking condition as described in any one of the first aspects of this application. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 A flowchart illustrating a method for estimating reference vehicle speed under hill braking conditions, provided in an embodiment of this application;

[0052] Figure 2 This is a schematic diagram of a reference vehicle speed estimation device for hill braking conditions provided in an embodiment of this application. Detailed Implementation

[0053] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0054] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0055] Example 1

[0056] Please refer to Figure 1 , Figure 1 This embodiment provides a flowchart illustrating a method for estimating reference vehicle speed under hill-start braking conditions. The method includes:

[0057] S101. Obtain the actual wheel speed of the target vehicle and the acceleration detection value of the vehicle acceleration sensor.

[0058] S102. Calculate wheel acceleration based on actual wheel speed.

[0059] S103. Determine the wheel adhesion state of the target vehicle based on the wheel acceleration and the preset acceleration boundary threshold.

[0060] In this embodiment, the wheel attachment state is either a wheel unstable state or a wheel not unstable state.

[0061] In this embodiment, the method calculates the acceleration of each wheel based on its wheel speed. Acceleration boundaries (A1 / A2 / A3) are set according to the road surface type (high adhesion / medium adhesion / low adhesion). Specifically, the method determines whether the acceleration of each wheel exceeds the adhesion boundary based on the current road surface type. If it does, the wheel becomes unstable; otherwise, it maintains adhesion and remains stable. The acceleration boundaries (A1 / A2 / A3) are confirmed through actual vehicle testing.

[0062] S104. When the wheel is in an unstable state, obtain the vehicle acceleration and the wheel speed at the moment of instability, and calculate and estimate the wheel speed based on the wheel speed at the moment of instability and the vehicle acceleration; or when the wheel is in an unstable state, determine the actual wheel speed as the estimated wheel speed.

[0063] In this embodiment, the method can calculate the estimated wheel speed of the unstable wheel by integrating the vehicle acceleration signal based on the wheel speed value at the moment of instability after the wheel becomes unstable.

[0064] In this embodiment, when the wheel is not unstable, the estimated wheel speed is equal to its actual wheel speed.

[0065] In this embodiment, each wheel has one wheel speed. Therefore, an unspecified wheel speed may refer to a single wheel speed or multiple wheel speeds.

[0066] S105. Determine the number of non-unstable wheels among the four wheels of the target vehicle based on the wheel adhesion status.

[0067] S106. When the number of non-unstable wheels is 0 or 4, calculate the average value based on the estimated wheel speed to obtain the initial reference speed; or when the number of non-unstable wheels is greater than 0 and less than 4, identify the non-unstable wheels and calculate the average value based on the estimated wheel speed of the non-unstable wheels to obtain the initial reference speed.

[0068] In this embodiment, when all four wheels are stable, the average speed of the four stable wheels is used. When some wheels are unstable, the average speed of the remaining stable wheels is used.

[0069] In this embodiment, when all four wheels are unstable, the average of the estimated wheel speeds of the four wheels (V) is used. avg ).

[0070] S107. Determine the maximum value of the actual wheel speed of the four wheels based on the actual wheel speed.

[0071] S108. Calculate the normal deviation based on the initial and maximum values ​​of the reference vehicle speed.

[0072] S109. Obtain the average speed of the stabilizing wheels and calculate the stabilization deviation based on the average speed of the stabilizing wheels and the initial reference speed.

[0073] S110. Calculate and estimate the error based on the normal deviation and the stabilization deviation.

[0074] In this embodiment, during braking, the stability state of the wheels rapidly switches between partial wheel instability and complete wheel instability. The wheel speed when all wheels are unstable depends on the accuracy of the estimated wheel speed obtained by integrating the vehicle body acceleration. Since the vehicle body acceleration signal itself is also an estimate, it is necessary to calculate and correct the current estimation deviation.

[0075] The estimation error (E) consists of normal deviation and stabilization deviation.

[0076] Normal deviation (E) norm Normal deviation is merely an estimate characterizing the error trend, and its value is V. avg Subtract the maximum actual wheel speed of the four wheels (V) max ).

[0077] Stabilization deviation (E) stb ): The average speed (V) of the wheels that have regained stability when the wheel stability changes from complete instability to partial wheel stability. stb This can represent the actual vehicle speed at that time. Therefore, the stabilization deviation E stb =V stb -V avg When the vehicle partially stabilizes and then re-enters a state of complete instability, E stb The value is locked until the next time a wheel comes to a stop before it is refreshed.

[0078] Specifically, the estimation error is a weighted average of the normal deviation and the stabilization deviation, and its weighting factor (k) is determined by E. norm The rate of change is determined by looking up a table, and the specific table value is determined by actual vehicle testing. The calculation formula is as follows:

[0079] E = k * E norm +(1-k)*E stb .

[0080] S111. Calculate the current vehicle acceleration of the target vehicle based on the estimation error and the acceleration detection value.

[0081] In this embodiment, the current vehicle acceleration ab is calculated by subtracting the slope component gsin(θ+γ) from the acceleration sensor value ax:

[0082] a b =a x -gsin(θ+γ);

[0083] Where θ is the dynamically estimated slope value, output by the dynamic slope estimation logic.

[0084] γ is the closed-loop slope correction value, which is calculated by a PI (proportional-integral) controller. The input of the controller is E, and the output is γ.

[0085] In this embodiment, it can be seen that the vehicle acceleration output by this method is a necessary input for the previous steps, thereby enabling continuous control loops for the aforementioned multiple steps. This allows for rapid correction of speed estimation errors, significantly improving the accuracy of speed estimation during ramp braking. Specifically, based on the above description, it can be understood that after step S111, this method can continue to execute steps S104 to S111, thus forming a control loop.

[0086] In this embodiment, the aforementioned current vehicle acceleration can be used to calculate and estimate the wheel speed when performing reference vehicle speed estimation and the wheel adhesion state is wheel instability.

[0087] In this embodiment, the significance of calculating the reference vehicle speed lies in the fact that when a wheel slips or tends to lock up, it loses traction, and its wheel speed cannot represent the vehicle's true speed. In this case, software algorithms are needed to estimate the vehicle's speed. Therefore, this method should be applied to scenarios where one or more wheels are unstable.

[0088] In this embodiment, the subject executing the method can be a computing device such as a computer or server, and no limitation is made in this embodiment.

[0089] In this embodiment, the subject executing the method can also be a smart device such as a smartphone or tablet, and no limitation is made in this embodiment.

[0090] As can be seen, the reference vehicle speed estimation method for hill braking described in this embodiment can accurately estimate the reference vehicle speed during hill braking based on error estimation closed-loop correction using readily available sensor hardware configurations in general mass-produced vehicles. This avoids the reliance on vehicle models in traditional methods, allowing the method to estimate based on the wheel adhesion state, thereby greatly improving the practicality and scalability of the method, and also helping to improve the adaptability and efficiency of different vehicle models.

[0091] Example 2

[0092] Please refer to Figure 2 , Figure 2 This is a schematic diagram of a reference vehicle speed estimation device for hill braking conditions provided in this embodiment. Figure 2 As shown, the reference vehicle speed estimation device for this slope braking condition includes:

[0093] The acquisition unit 210 is used to acquire the actual wheel speed of the target vehicle and the acceleration detection value of the vehicle acceleration sensor;

[0094] The first determining unit 220 is used to determine the wheel adhesion state of the target vehicle based on the actual wheel speed.

[0095] The second determining unit 230 is used to determine the estimated wheel speed of the target vehicle based on the wheel adhesion state.

[0096] The estimation unit 240 is used to estimate the initial reference speed of the target vehicle based on the estimated wheel speed and wheel adhesion state.

[0097] The first calculation unit 250 is used to calculate the estimation error based on the initial value of the reference vehicle speed;

[0098] The second calculation unit 260 is used to calculate the current vehicle body acceleration of the target vehicle based on the estimation error and the acceleration detection value.

[0099] In this embodiment, the current vehicle acceleration can be used to calculate and estimate the wheel speed when the reference vehicle speed is estimated and the wheel adhesion state is wheel instability.

[0100] As an optional implementation, the first determining unit 220 includes:

[0101] The first calculation subunit 221 is used to calculate the wheel acceleration based on the actual wheel speed.

[0102] The first determining subunit 222 is used to determine the wheel adhesion state of the target vehicle based on the wheel acceleration and a preset acceleration boundary threshold; wherein the wheel adhesion state is either a wheel instability state or a wheel non-instability state.

[0103] As an optional implementation, the second determining unit 230 is specifically used to obtain the vehicle body acceleration and the wheel speed value at the moment of instability when the wheel adhesion state is the wheel instability state, and to calculate and estimate the wheel speed based on the wheel speed value at the moment of instability and the vehicle body acceleration; when the wheel adhesion state is the wheel not instability state, the actual wheel speed is determined as the estimated wheel speed.

[0104] As an optional implementation, the estimation unit 240 includes:

[0105] The second determining subunit 241 is used to determine the number of non-unstable wheels among the four wheels of the target vehicle based on the wheel attachment state.

[0106] The second calculation subunit 242 is used to calculate the average value of the estimated wheel speed when the number of non-unstable wheels is 0 or 4, and obtain the initial value of the reference vehicle speed.

[0107] The second determining subunit 241 is also used to determine the unstable wheels when the number of unstable wheels is greater than 0 and less than 4, and to calculate the average value of the estimated wheel speed of the unstable wheels to obtain the initial value of the reference speed.

[0108] As an optional implementation, the first computing unit 250 includes:

[0109] The third determining subunit 251 is used to determine the maximum value of the actual wheel speed of the four wheels based on the actual wheel speed;

[0110] The third calculation subunit 252 is used to calculate the normal deviation based on the initial and maximum values ​​of the reference vehicle speed;

[0111] The third calculation subunit 252 is also used to obtain the average speed of the stabilizing wheels and calculate the stabilization deviation based on the average speed of the stabilizing wheels and the initial reference speed.

[0112] The third calculation subunit 252 is also used to calculate the estimation error based on the normal deviation and the stabilization deviation.

[0113] In this embodiment, the explanation of the reference speed estimation device for the slope braking condition can be referred to the description in Embodiment 1, and will not be repeated here.

[0114] As can be seen, the reference vehicle speed estimation device for hill braking described in this embodiment can accurately estimate the reference vehicle speed during hill braking based on the error estimation closed-loop correction method using readily available sensor hardware configurations in general mass-produced vehicles. This avoids the reliance on vehicle models in traditional devices, allowing the device to estimate based on the wheel adhesion state, thereby greatly improving the device's operability and scalability, and also improving the adaptability and efficiency of different vehicle models.

[0115] This application provides an electronic device, including a memory and a processor. The memory stores a computer program, and the processor runs the computer program to enable the electronic device to perform the reference vehicle speed estimation method for hill braking conditions in embodiment 1 of this application.

[0116] This application provides a computer-readable storage medium storing computer program instructions. When the computer program instructions are read and executed by a processor, the reference vehicle speed estimation method for the ramp braking condition in embodiment 1 of this application is performed.

[0117] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0118] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0119] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0120] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0121] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0122] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A method of estimating a reference vehicle speed in a hill-hold braking condition, characterized by, The method comprises: acquiring actual wheel speeds of a target vehicle and an acceleration detection value of a vehicle acceleration sensor; determining a wheel adhesion state of the target vehicle according to the actual wheel speeds; determining an estimated wheel speed of the target vehicle according to the wheel adhesion state; estimating a reference vehicle speed initial value of the target vehicle according to the estimated wheel speed and the wheel adhesion state; calculating an estimation error according to the reference vehicle speed initial value; calculating a current vehicle body acceleration of the target vehicle according to the estimation error and the acceleration detection value.

2. The method of estimating a reference vehicle speed for a hill-hold operating condition according to claim 1, wherein, The determination of the wheel adhesion state of the target vehicle according to the actual wheel speeds comprises: calculating a wheel acceleration according to the actual wheel speeds; determining the wheel adhesion state of the target vehicle according to the wheel acceleration and a preset acceleration boundary threshold value; wherein the wheel adhesion state is a wheel instability state or a wheel non-instability state.

3. The method of estimating a reference vehicle speed for a hill-hold operating condition according to claim 2, wherein, The determination of the estimated wheel speed of the target vehicle according to the wheel adhesion state comprises: when the wheel adhesion state is the wheel instability state, acquiring a vehicle body acceleration and a wheel speed value at an instability moment, and calculating an estimated wheel speed according to the wheel speed value at the instability moment and the vehicle body acceleration; when the wheel adhesion state is the wheel non-instability state, determining the actual wheel speed as the estimated wheel speed.

4. The method of estimating a reference vehicle speed for a hill brake condition according to claim 1, characterized in that, The estimation of the reference vehicle speed initial value of the target vehicle according to the estimated wheel speed and the wheel adhesion state comprises: determining a number of non-instability wheels among four wheels of the target vehicle according to the wheel adhesion state; when the number of non-instability wheels is 0 or 4, calculating an average value according to the estimated wheel speed to obtain the reference vehicle speed initial value; when the number of non-instability wheels is greater than 0 and less than 4, determining a non-instability wheel, and calculating an average value according to the estimated wheel speed of the non-instability wheel to obtain the reference vehicle speed initial value.

5. The method of estimating a reference vehicle speed for a hill-hold operating condition according to claim 1, wherein, The calculation of the estimation error according to the reference vehicle speed initial value comprises: determining a maximum value of four actual wheel speeds according to the actual wheel speeds; calculating a normal deviation according to the reference vehicle speed initial value and the maximum value; acquiring an average value of wheel speeds of recovery stability wheels, and calculating a recovery stability deviation according to the average value of the wheel speeds of the recovery stability wheels and the reference vehicle speed initial value; calculating the estimation error according to the normal deviation and the recovery stability deviation.

6. A device for estimating a reference vehicle speed in a hill-hold braking condition, characterized by The reference vehicle speed estimation device for the hill braking working condition comprises: an acquiring unit, configured to acquire actual wheel speeds of a target vehicle and an acceleration detection value of a vehicle acceleration sensor; a first determining unit, configured to determine a wheel adhesion state of the target vehicle according to the actual wheel speeds; a second determining unit, configured to determine an estimated wheel speed of the target vehicle according to the wheel adhesion state; an estimating unit, configured to estimate a reference vehicle speed initial value of the target vehicle according to the estimated wheel speed and the wheel adhesion state; a first calculating unit, configured to calculate an estimation error according to the reference vehicle speed initial value; a second calculating unit, configured to calculate a current vehicle body acceleration of the target vehicle according to the estimation error and the acceleration detection value.

7. The device for estimating a reference vehicle speed in a hill-hold mode according to claim 6, characterized in that, The first determining unit comprises: The first calculation subunit is configured to calculate wheel acceleration according to the actual wheel speed; The first determination subunit is configured to determine a wheel adhesion state of the target vehicle according to the wheel acceleration and a preset acceleration boundary threshold value, wherein the wheel adhesion state is a wheel instability state or a wheel non-instability state.

8. The device for estimating a reference vehicle speed in a hill-hold mode according to claim 7, characterized in that, The second determination unit is specifically configured to, when the wheel adhesion state is the wheel instability state, acquire a vehicle body acceleration and a wheel speed value at an instability moment, and calculate an estimated wheel speed according to the wheel speed value at the instability moment and the vehicle body acceleration; and when the wheel adhesion state is the wheel non-instability state, determine the actual wheel speed as the estimated wheel speed.

9. An electronic device, comprising: The electronic device comprises a memory and a processor, the memory is used for storing a computer program, and the processor runs the computer program to enable the electronic device to execute the reference vehicle speed estimation method in the hill braking working condition according to any one of claims 1 to 5.

10. A readable storage medium, characterized by, The readable storage medium stores computer program instructions, and the computer program instructions are read and run by a processor to execute the reference vehicle speed estimation method in the hill braking working condition according to any one of claims 1 to 5.

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