Antilock brake control method without wheel speed sensor

Abstract

This application relates to the field of vehicle braking control technology, and in particular to an anti-lock braking control method that does not require wheel speed sensors. The method includes acquiring current longitudinal acceleration data and current braking pressure data of the target vehicle during braking; determining disturbance braking pressure data based on the current braking pressure data, and controlling a valve body to adjust the disturbance based on the disturbance braking pressure data; determining acceleration change rate data and road adhesion coefficient change trend based on the longitudinal acceleration data of the vehicle before and after the disturbance; determining the target vehicle's operating point position state based on the direction of the braking pressure disturbance; and generating a braking pressure adjustment command, wherein the braking pressure adjustment command is used to adjust the current braking pressure of the target vehicle. This application improves the convenience of anti-lock braking control and reduces hardware maintenance costs.

Description

Technical Field

[0001] This application relates to the field of vehicle braking control technology, and in particular to an anti-lock braking control method that does not require wheel speed sensors. Background Technology

[0002] Currently, anti-lock braking system (ABS) is an important component of vehicle braking control. It is typically used to regulate braking pressure during vehicle braking to reduce the probability of wheels locking up and to help maintain directional controllability and driving stability during vehicle braking.

[0003] Existing anti-lock braking systems (ABS) typically rely on wheel speed sensors mounted at the wheels to collect wheel rotation speed information. Based on this information, they calculate parameters such as wheel angular velocity, vehicle speed, or slip ratio. Then, based on the relationship between the slip ratio and a preset control range, they control the braking pressure by increasing, decreasing, or maintaining pressure. This approach can determine the wheel braking status based on changes in wheel rotation speed, but it requires the installation of wheel speed sensors, their associated wiring, mounting structures, and signal processing units on the vehicle. However, the installation and wiring of wheel speed sensors increase the complexity of vehicle assembly. Furthermore, sensors are prone to signal distortion or hardware failure in harsh environments such as bumpy roads, mud and sand obstruction, or wear, leading to increased maintenance costs. Moreover, if wheel speed signals are lost, existing systems cannot achieve stable anti-lock control, thus leaving room for improvement. Summary of the Invention

[0004] To improve the convenience of anti-lock braking control and reduce hardware maintenance costs, this application provides an anti-lock braking control method that does not require wheel speed sensors.

[0005] The above-mentioned inventive objective of this application is achieved through the following technical solutions:

[0006] An anti-lock braking control method without wheel speed sensors is applied to an anti-lock braking control system including an electronic control unit and a valve body. The electronic control unit has a built-in vehicle acceleration sensor, and the valve body has a built-in hydraulic pressure sensor. The anti-lock braking control method includes:

[0007] During the braking process of the target vehicle, the current longitudinal acceleration data a of the target vehicle in the current braking cycle is acquired. x And current braking pressure data P b ;

[0008] According to the current braking pressure data P b Determine the disturbance braking pressure data P b The system generates a disturbance braking pressure adjustment command, which controls the valve body to adjust the pressure according to the disturbance braking pressure data P. b'Perform disturbance adjustment on the current braking pressure of the target vehicle;'

[0009] Based on the vehicle longitudinal acceleration data before and after the disturbance adjustment, determine the acceleration change rate data. and the trend of changes in road surface adhesion coefficient;

[0010] Based on the current braking pressure data P b and the disturbance braking pressure data P b ', determine the direction of the braking pressure disturbance, and based on the acceleration change rate data. The direction of the braking pressure disturbance and the trend of the road surface adhesion coefficient are used to determine the working point position of the target vehicle in the current braking cycle.

[0011] Based on the working point position state, a brake pressure adjustment command is generated for the current braking cycle, wherein the brake pressure adjustment command is used to adjust the current brake pressure of the target vehicle.

[0012] By adopting the above technical solution, the current longitudinal acceleration data and current braking pressure data of the vehicle are acquired during braking. Based on the current braking pressure data, disturbance braking pressure data is determined, allowing the valve body to adjust the current braking pressure according to the disturbance braking pressure data. This enables the establishment of a correspondence between braking pressure changes and the vehicle's longitudinal acceleration response without collecting wheel speed signals. By determining the acceleration change rate data and the road adhesion coefficient change trend based on the vehicle's longitudinal acceleration data before and after disturbance adjustment, and combining this with the direction of braking pressure disturbance, the operating point position state within the current braking cycle can be determined. This allows the system to determine whether the current braking operating point is in a stable region, a lock-up trend region, or near a peak value. By generating braking pressure adjustment commands based on the operating point position state, the braking pressure can be adjusted accordingly based on the current braking operating point state without the need for wheel speed sensors and slip ratio calculations. This reduces the reliance of anti-lock braking control on wheel speed sensors and their associated structures, improving the system's economy and ease of maintenance.

[0013] In a preferred embodiment, this application can be further configured as follows: during the braking process of the target vehicle, the current longitudinal acceleration data a of the target vehicle in the current braking cycle is acquired. x And current braking pressure data P b Specifically, it includes:

[0014] When the braking pressure of the target vehicle is detected to be generated or changed, it is determined that the target vehicle has entered the current braking cycle;

[0015] During the current braking cycle, the initial longitudinal acceleration data a of the vehicle is acquired by the vehicle acceleration sensor.x0 And the initial braking pressure data P acquired through the oil pressure sensor. b0 ;

[0016] The initial longitudinal acceleration data a of the whole vehicle were respectively... x0 and the initial braking pressure data P b0 After filtering, the current longitudinal acceleration data a of the whole vehicle is obtained. x and the current braking pressure data P b .

[0017] By adopting the above technical solution, the target vehicle enters the current braking cycle when the braking pressure is detected to be generated or changed, and the initial vehicle longitudinal acceleration data and initial braking pressure data are collected within the current braking cycle. This enables the braking pressure input and the vehicle longitudinal acceleration response to correspond within the same control cycle. By filtering the initial data, signal noise caused by road bumps or electromagnetic interference can be filtered out, thereby improving the stability of the current vehicle longitudinal acceleration data and current braking pressure data.

[0018] In a preferred embodiment, this application can be further configured such that: the step based on the current braking pressure data P... b Determine the disturbance braking pressure data P b Specifically, it includes:

[0019] Obtain preset disturbance signal parameters, wherein the disturbance signal parameters include at least disturbance amplitude parameters and disturbance frequency parameters;

[0020] A pressure disturbance signal is generated based on the disturbance amplitude parameter and the disturbance frequency parameter;

[0021] The current braking pressure data P b The disturbance braking pressure data P is obtained by superimposing the disturbance signal with the disturbance signal. b '.

[0022] By adopting the above technical solution, by obtaining the disturbance amplitude parameters and disturbance frequency parameters, and generating a pressure disturbance signal based on the disturbance signal parameters and superimposing it on the current braking pressure data, pressure testing conditions are provided for subsequent determination of the working point position status based on the longitudinal acceleration response of the vehicle.

[0023] In a preferred embodiment, this application can be further configured such that the disturbance braking pressure data is based on formula P. b '=P b +A·sin(ωt) is determined, where P b 'P' represents the disturbance braking pressure data. bHere, A is the current braking pressure data, ω is the disturbance amplitude parameter, t is the disturbance frequency parameter, and t is the current time corresponding to the current braking cycle. The value range of the disturbance amplitude parameter is 0.1MPa to 0.5MPa, and the value range of the disturbance frequency parameter is 2Hz to 20Hz.

[0024] By adopting the above technical solution, by adopting P b '=P b +A·sin(ωt) determines the disturbance braking pressure data and limits the range of values ​​for the disturbance amplitude parameter and the disturbance frequency parameter. This enables the disturbance braking pressure to form a periodic small change around the current braking pressure, reducing the interference of pressure disturbance on the current braking pressure regulation process.

[0025] In a preferred embodiment, this application can be further configured to: determine the rate of change of acceleration data based on the longitudinal acceleration data of the vehicle before and after the disturbance adjustment. And the trend of changes in road surface adhesion coefficient, specifically including:

[0026] Acquire the longitudinal acceleration data a of the target vehicle after disturbance during the current braking cycle. x Based on the current longitudinal acceleration data of the whole vehicle a x The absolute value of the longitudinal acceleration data of the whole vehicle after the disturbance, a x The acceleration change rate data is calculated by taking the absolute value of ' and the corresponding control cycle time interval. ;

[0027] Based on the current vehicle longitudinal acceleration data a x Estimate the current road surface adhesion coefficient μ, and based on the longitudinal acceleration data a of the vehicle after the disturbance. x 'Estimate the road surface adhesion coefficient μ after disturbance';

[0028] The current road surface adhesion coefficient μ and the road surface adhesion coefficient μ' after disturbance are compared to determine the trend of road surface adhesion coefficient change. The trend of road surface adhesion coefficient change includes an increasing trend of road surface adhesion coefficient, a decreasing trend of road surface adhesion coefficient, and a stable trend of road surface adhesion coefficient.

[0029] By adopting the above technical solution, the acceleration change rate data is determined based on the longitudinal acceleration data of the whole vehicle before and after the disturbance adjustment, and the current road adhesion coefficient and the road adhesion coefficient after the disturbance are estimated respectively. The changing trend of vehicle deceleration response and adhesion state before and after pressure disturbance can be obtained, thereby providing a basis for judging the position of the current braking working point relative to the peak value of the road adhesion coefficient.

[0030] In a preferred embodiment, this application can be further configured such that the calculation process of the road surface adhesion coefficient specifically includes:

[0031] Obtain the vehicle dynamics parameters of the target vehicle, wherein the vehicle dynamics parameters include at least the total vehicle mass and wheel vertical load;

[0032] Based on the vehicle's longitudinal acceleration data, the vehicle's total mass, and the wheel's vertical load, the formula μ=(|a|·M) / F is used. z The corresponding road surface adhesion coefficient is calculated, where μ is the road surface adhesion coefficient, |a| is the absolute value of the vehicle's longitudinal acceleration data, M is the total mass of the vehicle, and F... z The vertical load on the wheel is given.

[0033] By adopting the above technical solution, by obtaining the total mass of the vehicle and the vertical load of the wheels, and calculating the corresponding road adhesion coefficient based on the absolute value of the longitudinal acceleration data of the whole vehicle, the longitudinal acceleration response of the whole vehicle can be converted into road adhesion state parameters, so that the current road adhesion coefficient and the road adhesion coefficient after disturbance can be compared, thereby improving the ability to perceive different road adhesion conditions.

[0034] In a preferred embodiment, this application can be further configured such that: the basis of the current braking pressure data P b and the disturbance braking pressure data P b Determine the direction of the braking pressure disturbance, specifically including:

[0035] The disturbance braking pressure data P b 'Compared with the current braking pressure data P b By comparing the values, the difference in braking pressure disturbance is obtained;

[0036] When the disturbance braking pressure data P b 'Greater than the current braking pressure data P' b When the absolute value of the brake pressure disturbance difference is greater than the preset pressure disturbance threshold, the direction of the brake pressure disturbance is determined to be the pressure boosting direction.

[0037] When the disturbance braking pressure data P b 'Less than the current braking pressure data P' b When the absolute value of the braking pressure disturbance difference is greater than the preset pressure disturbance threshold, the braking pressure disturbance direction is determined to be the decompression direction.

[0038] By adopting the above technical solution, by comparing the disturbed braking pressure data with the current braking pressure data, and by combining the preset pressure disturbance threshold to determine the direction of braking pressure disturbance, it is possible to distinguish between effective pressure increase direction disturbance and pressure decrease direction disturbance, thereby providing a directional basis for subsequent judgment of the pressure disturbance effect by combining acceleration change rate data and road adhesion coefficient change trend.

[0039] In a preferred embodiment, this application can be further configured such that: the operating point position state includes at least a stable region state, a dead-end trend region state, and a peak near-state, and the state is based on the acceleration rate of change data. The direction of the braking pressure disturbance and the trend of the road surface adhesion coefficient are used to determine the operating point position of the target vehicle within the current braking cycle, specifically including:

[0040] If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point position state is determined to be the stable zone state.

[0041] If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data If the value is less than zero and the trend of the road surface adhesion coefficient is a decreasing trend, then the working point position state is determined to be the lock-up trend zone state.

[0042] If the direction of the braking pressure disturbance is the decompression direction, and the acceleration change rate data If the value is less than zero and the trend of the road surface adhesion coefficient is a decreasing trend, then the working point position state is determined to be the stable zone state.

[0043] If the direction of the braking pressure disturbance is the decompression direction, and the acceleration change rate data If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point position state is determined to be the lock-up trend zone state.

[0044] If the acceleration change rate data If the absolute value of the road surface adhesion coefficient is less than the preset rate of change threshold, and the trend of the road surface adhesion coefficient change is a stable trend, then the working point position state is determined to be near the peak value.

[0045] By adopting the above technical solution, the stable zone state, the lock-up trend zone state, or the state near the peak can be determined based on the direction of braking pressure disturbance, the acceleration change rate data, and the change trend of road adhesion coefficient. This allows for the correspondence between the vehicle deceleration response changes after pressure disturbance and the changes in road adhesion state, which helps to classify the braking state and improve the pertinence of judging the current braking working point position.

[0046] In a preferred embodiment, this application can be further configured such that: the brake pressure adjustment command includes at least a pressure increase command, a pressure decrease command, and a pressure hold command; and the generation of the brake pressure adjustment command for the current braking cycle based on the operating point position state specifically includes:

[0047] When the working point position is in the stable zone state, the boost command is generated, and the boost command is used to increase the braking pressure of the target vehicle in the current braking cycle;

[0048] When the working point position is in the lock-up tendency zone state, the decompression command is generated, and the decompression command is used to reduce the braking pressure of the target vehicle in the current braking cycle;

[0049] When the operating point position is near the peak value, the pressure holding command is generated to maintain the braking pressure of the target vehicle during the current braking cycle.

[0050] By adopting the above technical solution, by generating a boost command in the stable region, a depressurization command in the lock-up trend region, and a pressure holding command near the peak value, the braking pressure adjustment action can correspond to the current braking operating point position, thereby achieving periodic adjustment of the braking pressure.

[0051] In summary, this application includes at least one of the following beneficial technical effects:

[0052] 1. By acquiring current vehicle longitudinal acceleration data and current braking pressure data during braking, and determining disturbance braking pressure data based on the current braking pressure data, the valve body adjusts the current braking pressure according to the disturbance braking pressure data. This allows for the establishment of a correspondence between braking pressure changes and vehicle longitudinal acceleration response without collecting wheel speed signals. Furthermore, by determining the acceleration change rate data and road adhesion coefficient change trend based on the vehicle longitudinal acceleration data before and after disturbance adjustment, and combining this with the direction of braking pressure disturbance, the operating point position within the current braking cycle can be determined. This enables the system to identify whether the current braking operating point is in a stable zone, a lock-up tendency zone, or near a peak value. By generating braking pressure adjustment commands based on the operating point position, the braking pressure can be adjusted accordingly based on the current braking operating point state without the need for wheel speed sensors and slip ratio calculations. This reduces the reliance of anti-lock braking control on wheel speed sensors and their associated structures, improving the system's economy and ease of maintenance.

[0053] 2. By generating boost commands in the stable region, depressurization commands in the lock-up trend region, and pressure holding commands near the peak value, the brake pressure adjustment action can correspond to the current brake operating point position, thereby achieving periodic adjustment of the brake pressure. Attached Figure Description

[0054] Figure 1 This is a flowchart illustrating the implementation of an anti-lock braking control method without wheel speed sensors in one embodiment of this application. Detailed Implementation

[0055] The following embodiments will help those skilled in the art to further understand the function of this application, but do not limit this application in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of this application. These all fall within the protection scope of this application.

[0056] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0057] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0058] The present application will be further described in detail below with reference to the accompanying drawings.

[0059] In one embodiment, such as Figure 1 As shown, this application discloses an anti-lock braking control method without wheel speed sensors. This method is applied to an anti-lock braking control system including an electronic control unit and a valve body. The electronic control unit has a built-in vehicle acceleration sensor, and the valve body has a built-in hydraulic pressure sensor. Specifically, it includes the following steps:

[0060] S10. During the braking process of the target vehicle, acquire the current longitudinal acceleration data of the target vehicle within the current braking cycle. x And current braking pressure data P b .

[0061] In this embodiment, the target vehicle refers to a vehicle undergoing braking. The current braking cycle refers to the control cycle used by the target vehicle during braking to perform one braking state acquisition, pressure disturbance, response judgment, and pressure adjustment. The current longitudinal acceleration data a of the entire vehicle. x This refers to the acceleration data corresponding to the vehicle's longitudinal braking response within the current braking cycle, and the current braking pressure data P. b This refers to the pressure data corresponding to the vehicle's braking actuator during the current braking cycle.

[0062] Specifically, during the braking process of the target vehicle, the longitudinal acceleration data of the target vehicle during the current braking cycle is acquired through the built-in vehicle acceleration sensor, and the braking pressure data of the target vehicle during the current braking cycle is acquired through the hydraulic pressure sensor built into the valve body. The processed longitudinal acceleration data is then used as the current longitudinal acceleration data of the vehicle. x The processed brake pressure data is used as the current brake pressure data P. b Among them, the current longitudinal acceleration data of the whole vehicle a x The current braking pressure data P is used as the basis for judging changes in the braking response of a target vehicle. b This data will be used as the basis for determining the disturbance braking pressure data Pb'.

[0063] S20, Based on the current braking pressure data P b Determine the disturbance braking pressure data P b ', Generates a disturbance braking pressure adjustment command, which is used to control the valve body according to the disturbance braking pressure data P b 'Perform disturbance adjustment on the current braking pressure of the target vehicle.'

[0064] In this embodiment, the disturbed braking pressure data Pb' refers to the data at the current braking pressure data P b The braking pressure data is obtained by superimposing a pressure disturbance signal on the basis of the data. The disturbance braking pressure adjustment command refers to the command used to control the valve body according to the disturbance braking pressure data P. b 'Execute the control command for pressure disturbance regulation, which is used to create a tentative pressure change near the current braking pressure.'

[0065] Specifically, based on the current braking pressure data P b Determine the disturbance braking pressure data P b ', and based on the disturbance braking pressure data P b Generate a disturbance braking pressure adjustment command and send it to the valve body, causing the valve body to adjust the pressure according to the disturbance braking pressure data P. bThe current braking pressure of the target vehicle is disturbed and adjusted, so that the target vehicle produces a corresponding longitudinal acceleration response change after the disturbance adjustment, so as to determine the position state of the current braking point based on the response change.

[0066] S30. Based on the vehicle longitudinal acceleration data before and after disturbance adjustment, determine the acceleration change rate data. And the changing trend of road surface adhesion coefficient.

[0067] In this embodiment, the vehicle longitudinal acceleration data before and after disturbance adjustment includes the current vehicle longitudinal acceleration data a before disturbance adjustment. x The longitudinal acceleration data of the whole vehicle after disturbance adjustment a x 'Acceleration rate of change data' The change trend of the road surface adhesion coefficient is used to represent the change in the absolute value of the longitudinal acceleration of the vehicle before and after disturbance adjustment.

[0068] Specifically, the valve body is adjusted according to the disturbance braking pressure data P. b After completing the disturbance adjustment, acquire the longitudinal acceleration data of the whole vehicle after the disturbance. x ', based on the current longitudinal acceleration data of the whole vehicle a x And the longitudinal acceleration data of the whole vehicle after disturbance a x Determine the rate of change of acceleration data The corresponding road adhesion coefficient is estimated based on the longitudinal acceleration data of the whole vehicle before and after the disturbance adjustment. The trend of the road adhesion coefficient change is determined by comparing the road adhesion coefficient before and after the disturbance adjustment, thus forming the acceleration response basis and adhesion status basis for judging the working point position status.

[0069] S40, Based on current brake pressure data P b And disturbance braking pressure data P b 'Determine the direction of the braking pressure disturbance based on the acceleration rate of change data'. By analyzing the direction of braking pressure disturbance and the trend of road surface adhesion coefficient changes, the operating point position of the target vehicle within the current braking cycle can be determined.

[0070] In this embodiment, the direction of brake pressure disturbance refers to the direction of the disturbed brake pressure data P. b 'Relative to the current braking pressure data P b The direction of change, the working point position state refers to the position state of the target vehicle's braking working point relative to the peak value of the road surface adhesion coefficient in the current braking cycle. The working point position state can include the stable zone state, the lock-up tendency zone state, and the state near the peak value.

[0071] Specifically, based on the current braking pressure data Pb And disturbance braking pressure data P b The magnitude relationship between the values ​​determines the direction of the braking pressure disturbance, and is combined with the acceleration rate of change data. The relationship between the vehicle's braking response and adhesion state after pressure disturbance is determined by the trend of road adhesion coefficient change. When the pressure increase direction disturbance increases the absolute value of the vehicle's longitudinal acceleration and road adhesion coefficient, or the pressure decrease direction disturbance decreases the absolute value of the vehicle's longitudinal acceleration and road adhesion coefficient, the current braking operating point is determined to be in the stable zone. When the pressure increase direction disturbance decreases the absolute value of the vehicle's longitudinal acceleration and road adhesion coefficient, or the pressure decrease direction disturbance increases the absolute value of the vehicle's longitudinal acceleration and road adhesion coefficient, the current braking operating point is determined to be in the lock-up tendency zone. When the changes in the absolute value of the vehicle's longitudinal acceleration and road adhesion coefficient before and after the disturbance are both small, the current braking operating point is determined to be near the peak value.

[0072] S50. Based on the working point position status, generate a brake pressure adjustment command for the current braking cycle, wherein the brake pressure adjustment command is used to adjust the current brake pressure of the target vehicle.

[0073] In this embodiment, the brake pressure adjustment command refers to the pressure control command generated based on the working point position state. The brake pressure adjustment command may include a pressure increase command, a pressure decrease command, and a pressure hold command. The pressure increase command is used to increase the current brake pressure of the target vehicle, the pressure decrease command is used to decrease the current brake pressure of the target vehicle, and the pressure hold command is used to maintain the current brake pressure of the target vehicle.

[0074] Specifically, when the operating point is in a stable state, a pressure boosting command is generated to increase the current braking pressure of the target vehicle. When the operating point is in a lock-up tendency state, a pressure reduction command is generated to decrease the current braking pressure of the target vehicle. When the operating point is near the peak value, a pressure holding command is generated to maintain the current braking pressure of the target vehicle. After completing the braking pressure adjustment in the current braking cycle, the system enters the next braking cycle and continues to perform data acquisition, pressure disturbance, state judgment, and pressure adjustment processes.

[0075] In one embodiment, in step S10, i.e. during the braking process of the target vehicle, the current longitudinal acceleration data a of the target vehicle in the current braking cycle is acquired. x And current braking pressure data P b Specifically, it includes:

[0076] S11. When the braking pressure of the target vehicle is detected to be generated or changed, determine that the target vehicle has entered the current braking cycle.

[0077] In this embodiment, "braking pressure generation" refers to the change in braking pressure from zero to one when the target vehicle enters the braking state from a non-braking state. "Braking pressure change" refers to the change in braking pressure, such as an increase, decrease, or fluctuation, when the target vehicle is already in the braking state. "Current braking cycle" refers to a control judgment cycle triggered based on this change in braking pressure.

[0078] Specifically, the braking pressure is continuously acquired by the oil pressure sensor built into the valve body. When the braking pressure is detected to have entered the braking pressure range from the preset no braking pressure range, or when the difference between the braking pressure at adjacent sampling times meets the preset change conditions, the target vehicle is determined to enter the current braking cycle, so that subsequent longitudinal acceleration acquisition, braking pressure acquisition, disturbance adjustment and working point position determination can be performed within the current braking cycle.

[0079] S12. During the current braking cycle, the initial longitudinal acceleration data a of the vehicle is acquired through the vehicle acceleration sensor. x0 And the initial braking pressure data P obtained through the oil pressure sensor. b0 .

[0080] In this embodiment, the initial longitudinal acceleration data of the whole vehicle a x0 This refers to the unfiltered raw longitudinal acceleration data of the whole vehicle and the initial braking pressure data P. b0 This refers to the raw, unfiltered brake pressure data, which is used to form the basis of the raw data for the current braking cycle.

[0081] Specifically, during the current braking cycle, the initial longitudinal acceleration data of the target vehicle is collected using the built-in vehicle acceleration sensor. x0 The initial braking pressure data P of the target vehicle is collected through the oil pressure sensor built into the valve body. b0 Simultaneously, based on the initial vehicle longitudinal acceleration data a at the time of acquisition... x0 and initial braking pressure data P b0 This allows for the corresponding application of braking pressure input and longitudinal acceleration response of the target vehicle within the same current braking cycle.

[0082] S13, respectively, the initial longitudinal acceleration data of the whole vehicle a x0 and initial braking pressure data P b0 After filtering, the current longitudinal acceleration data a of the whole vehicle is obtained. x And current braking pressure data P b .

[0083] In this embodiment, filtering is used to reduce the impact of road impact, vehicle body vibration, sensor noise, and transient fluctuations in braking pressure on subsequent judgments. The current vehicle longitudinal acceleration data a... x The data is the filtered longitudinal acceleration of the vehicle, and the current braking pressure data P. b This is the filtered braking pressure data.

[0084] Specifically, regarding the initial longitudinal acceleration data of the whole vehicle a x0 After filtering, the current longitudinal acceleration data a of the whole vehicle is obtained. x And the initial braking pressure data P b0 After filtering, the current braking pressure data P is obtained. b Among them, the current longitudinal acceleration data of the whole vehicle a x Data used for subsequent calculation of the rate of change of acceleration And estimate the current road surface adhesion coefficient μ, and the current braking pressure data P. b Used for subsequent determination of disturbance braking pressure data P b 'and the direction of braking pressure disturbance.

[0085] In one embodiment, in step S20, i.e., based on the current braking pressure data P b Determine the disturbance braking pressure data P b Specifically, it includes:

[0086] S21. Obtain preset disturbance signal parameters, wherein the disturbance signal parameters include at least disturbance amplitude parameters and disturbance frequency parameters.

[0087] In this embodiment, the disturbance signal parameter refers to the parameter used to generate the pressure disturbance signal, and the disturbance amplitude parameter is used to limit the pressure disturbance signal relative to the current braking pressure data P. b The variation range, and the disturbance frequency parameter are used to limit the frequency at which the pressure disturbance signal changes over time.

[0088] Specifically, during the current braking cycle, pre-set disturbance amplitude and frequency parameters are read to ensure that the subsequently generated pressure disturbance signal is compatible with the current braking pressure data P. b A small pressure change occurs nearby, which causes a change in the longitudinal acceleration response of the target vehicle, thereby providing response data for determining the position and status of the working point.

[0089] S22. Generate a pressure disturbance signal based on the disturbance amplitude parameter and the disturbance frequency parameter.

[0090] In this embodiment, the pressure disturbance signal refers to a time-varying pressure signal generated based on the disturbance amplitude parameter and the disturbance frequency parameter. This pressure disturbance signal is used to superimpose onto the current braking pressure data P.b Above, to form disturbance braking pressure data P b '.

[0091] Specifically, a pressure disturbance signal is generated based on the disturbance amplitude parameter, the disturbance frequency parameter, and the current time corresponding to the current braking cycle, so that the pressure disturbance signal has a corresponding disturbance amplitude and disturbance direction. When the value of the pressure disturbance signal is positive, it can form a pressure increase direction disturbance, and when the value of the pressure disturbance signal is negative, it can form a pressure decrease direction disturbance.

[0092] S23, Transfer the current braking pressure data P b The disturbance braking pressure data P is obtained by superimposing the disturbance signal onto the pressure disturbance signal. b '.

[0093] In this embodiment, the overlay process refers to overlaying the current braking pressure data P... b The disturbance braking pressure data P is obtained by adding the disturbance signal to the pressure disturbance signal. b 'This is the pressure target data obtained after overlay processing.'

[0094] Specifically, the current braking pressure data P b The disturbance braking pressure data Pb' is obtained by superimposing it with the pressure disturbance signal, and then the disturbance braking pressure data Pb' is used to obtain the disturbance braking pressure data Pb'. b Generate a disturbance braking pressure adjustment command, causing the valve body to adjust according to the disturbance braking pressure data P. b The target vehicle's current braking pressure is disturbed and adjusted so that the target vehicle generates a corresponding longitudinal acceleration response after the disturbance adjustment.

[0095] In one embodiment, in step S23, the disturbance braking pressure data is determined according to formula P. b '=P b +A·sin(ωt) is determined, where P b 'This is the data for the disturbance braking pressure, P' b Here is the current braking pressure data, A is the disturbance amplitude parameter, ω is the disturbance frequency parameter, and t is the current time corresponding to the current braking cycle. The value range of the disturbance amplitude parameter is 0.1MPa to 0.5MPa, and the value range of the disturbance frequency parameter is 2Hz to 20Hz.

[0096] In this embodiment, A·sin(ωt) is the pressure disturbance signal, the disturbance amplitude parameter A is used to limit the amplitude of the pressure disturbance signal, the disturbance frequency parameter ω is used to limit the frequency of change of the pressure disturbance signal in the current braking cycle, and the current time t is used to determine the instantaneous value of the pressure disturbance signal in the current braking cycle.

[0097] Specifically, when A·sin(ωt) is positive, the disturbance braking pressure data Pb 'Greater than the current braking pressure data P' b This results in a pressure disturbance in the boost direction. When A·sin(ωt) is negative, the disturbance braking pressure data P b 'Less than the current braking pressure data P' b This results in a pressure disturbance in the decompression direction. As the value of A·sin(ωt) changes, the disturbance braking pressure data P b 'Subsequently, in the current braking pressure data P b Based on changes in the vicinity, the position of the current braking point can be determined according to the direction of pressure disturbance and the longitudinal acceleration response of the vehicle.

[0098] In one embodiment, in step S30, the acceleration change rate data is determined based on the vehicle longitudinal acceleration data before and after disturbance adjustment. And the trend of changes in road surface adhesion coefficient, specifically including:

[0099] S31. Obtain the longitudinal acceleration data of the target vehicle after disturbance during the current braking cycle. x Based on the current longitudinal acceleration data of the whole vehicle, a x The absolute value of the longitudinal acceleration data of the whole vehicle after the disturbance a x The absolute value of ' and the corresponding control cycle time interval are used to calculate the acceleration change rate data. .

[0100] In this embodiment, the longitudinal acceleration data a of the entire vehicle after disturbance x 'Refers to the longitudinal acceleration data of the whole vehicle collected after the valve body completes disturbance adjustment according to the disturbance braking pressure data Pb', and the control cycle time interval refers to the current longitudinal acceleration data a of the whole vehicle. x The corresponding acquisition time and longitudinal acceleration data of the whole vehicle after disturbance a x 'The time interval between the corresponding data collection moments.'

[0101] Specifically, after the valve body completes the disturbance adjustment, the longitudinal acceleration data a of the whole vehicle after the disturbance is acquired. x ', and calculate the current longitudinal acceleration data of the whole vehicle a x The absolute value and longitudinal acceleration data of the whole vehicle after disturbance a x The absolute value of ', and then the longitudinal acceleration data of the whole vehicle after disturbance a x The absolute value of ' minus the current longitudinal acceleration data of the whole vehicle a x Dividing the absolute value of the acceleration by the corresponding control cycle time interval yields the acceleration rate of change data. , making the acceleration change rate data It can be used to determine whether the braking deceleration response of the target vehicle after disturbance adjustment increases, decreases, or tends to stabilize compared to before disturbance adjustment.

[0102] S32, Based on the current vehicle longitudinal acceleration data a x Estimate the current road surface adhesion coefficient μ, and based on the longitudinal acceleration data of the vehicle after the disturbance a. x 'Estimate the road surface adhesion coefficient μ after disturbance'.

[0103] In this embodiment, the current road surface adhesion coefficient μ refers to the coefficient of friction relative to the current longitudinal acceleration data a of the vehicle. x The corresponding road surface adhesion coefficient, the road surface adhesion coefficient μ' after disturbance refers to the coefficient of friction between the road surface adhesion coefficient μ' and the longitudinal acceleration data a of the vehicle after disturbance. x 'Corresponding road surface adhesion coefficient'.

[0104] Specifically, based on the current longitudinal acceleration data of the whole vehicle a x The vehicle's total mass and wheel vertical load are used to estimate the current road adhesion coefficient μ, and the longitudinal acceleration data a of the whole vehicle after disturbance is used to estimate the road adhesion coefficient μ. x The total vehicle mass and wheel vertical load are used to estimate the road adhesion coefficient μ after disturbance, so that the road adhesion state before and after disturbance adjustment can be compared in the form of road adhesion coefficient.

[0105] S33. Compare the current road surface adhesion coefficient μ with the road surface adhesion coefficient μ' after disturbance to determine the trend of road surface adhesion coefficient change. The trend of road surface adhesion coefficient change includes the trend of increasing road surface adhesion coefficient, the trend of decreasing road surface adhesion coefficient, and the trend of stable road surface adhesion coefficient.

[0106] In this embodiment, the trend of road surface adhesion coefficient change is used to indicate the direction of change of the road surface adhesion coefficient after disturbance adjustment relative to the road surface adhesion coefficient before disturbance adjustment. An increasing trend of road surface adhesion coefficient indicates that the road surface adhesion coefficient μ' after disturbance is greater than the current road surface adhesion coefficient μ. A decreasing trend of road surface adhesion coefficient indicates that the road surface adhesion coefficient μ' after disturbance is less than the current road surface adhesion coefficient μ. A stable trend of road surface adhesion coefficient indicates that the amount of change between the road surface adhesion coefficient μ' after disturbance and the current road surface adhesion coefficient μ is within a preset range.

[0107] Specifically, the current road surface adhesion coefficient μ and the road surface adhesion coefficient μ' after disturbance are compared. When the road surface adhesion coefficient μ' after disturbance is greater than the current road surface adhesion coefficient μ, the trend of road surface adhesion coefficient change is determined to be an increasing trend. When the road surface adhesion coefficient μ' after disturbance is less than the current road surface adhesion coefficient μ, the trend of road surface adhesion coefficient change is determined to be a decreasing trend. When the absolute value of the difference between the road surface adhesion coefficient μ' after disturbance and the current road surface adhesion coefficient μ is less than or equal to the preset adhesion coefficient change threshold, the trend of road surface adhesion coefficient change is determined to be a stable trend.

[0108] In one embodiment, step S32, namely the calculation process of the road surface adhesion coefficient, specifically includes:

[0109] S321. Obtain the vehicle dynamics parameters of the target vehicle, wherein the vehicle dynamics parameters include at least the total vehicle mass and the vertical load on the wheels.

[0110] In this embodiment, vehicle dynamics parameters are used to convert the longitudinal acceleration data of the whole vehicle into the corresponding road adhesion coefficient. The total vehicle mass refers to the whole vehicle mass parameter corresponding to the target vehicle. The wheel vertical load can be the equivalent vertical load parameter between the target vehicle's braking wheel assembly and the road surface, or it can be the vertical load parameter determined according to the vehicle load state, axle load distribution relationship, or preset vehicle parameters.

[0111] Specifically, the system reads the pre-stored total vehicle mass and wheel vertical load of the target vehicle, or obtains the corrected total vehicle mass and wheel vertical load based on the current load state of the target vehicle, so that the corresponding road adhesion coefficient can be calculated based on the longitudinal acceleration data of the whole vehicle.

[0112] S322. Based on the vehicle's longitudinal acceleration data, total vehicle mass, and wheel vertical load, the formula μ=(|a|·M) / F is used. z The corresponding road adhesion coefficient is calculated, where μ is the road adhesion coefficient, |a| is the absolute value of the vehicle's longitudinal acceleration data, M is the total mass of the vehicle, and F... z This refers to the vertical load on the wheel.

[0113] In this embodiment, the vehicle longitudinal acceleration data can be the current vehicle longitudinal acceleration data a. x It can also be the longitudinal acceleration data of the whole vehicle after the disturbance, a x The corresponding road surface adhesion coefficient can be the current road surface adhesion coefficient μ or the road surface adhesion coefficient μ' after disturbance.

[0114] Specifically, when the vehicle longitudinal acceleration data is the current vehicle longitudinal acceleration data a x At that time, based on the current longitudinal acceleration data of the whole vehicle a x The current road adhesion coefficient μ is calculated from the absolute value of the vehicle's total mass and the vertical load on the wheels. When the vehicle's longitudinal acceleration data is the disturbed vehicle longitudinal acceleration data a... x At that time, based on the longitudinal acceleration data of the whole vehicle after the disturbance, a x The road adhesion coefficient μ' after disturbance is calculated by taking the absolute value of ', the total mass of the vehicle and the vertical load of the wheels, so that the road adhesion coefficient before and after disturbance adjustment can be obtained by using the same calculation relationship.

[0115] In one embodiment, in step S40, based on the current braking pressure data P bAnd disturbance braking pressure data P b Determine the direction of the braking pressure disturbance, specifically including:

[0116] S41, Transfer the disturbance braking pressure data P b 'Compared with current brake pressure data P b By comparing the values, the difference in braking pressure disturbance is obtained.

[0117] In this embodiment, the brake pressure disturbance difference refers to the disturbance brake pressure data P. b 'Relative to the current braking pressure data P b The difference, the brake pressure disturbance difference, is used to represent the disturbance brake pressure data P. b 'Relative to the current braking pressure data P b The range of change.

[0118] Specifically, the disturbance braking pressure data P b 'Subtract the current braking pressure data P' b The braking pressure disturbance difference is obtained, and the braking pressure disturbance data P is used as a basis. b 'Compared with current brake pressure data P b The relationship between the magnitudes determines the direction of brake pressure change, and the absolute value of the brake pressure disturbance difference determines whether the pressure disturbance reaches the preset effective disturbance amplitude.

[0119] S42, When the disturbance braking pressure data P b 'Greater than the current braking pressure data P' b When the absolute value of the brake pressure disturbance difference is greater than the preset pressure disturbance threshold, the brake pressure disturbance direction is determined to be the pressure boosting direction.

[0120] In this embodiment, the pressure boosting direction refers to the disturbance braking pressure data P. b 'Relative to the current braking pressure data P b The direction of increase, and the preset pressure disturbance threshold are used to determine the disturbance braking pressure data P. b 'Compared with current brake pressure data P b Whether the pressure difference between them reaches the effective disturbance range.

[0121] Specifically, when the disturbance braking pressure data P b 'Greater than the current braking pressure data P' b Furthermore, if the absolute value of the braking pressure disturbance difference is greater than the preset pressure disturbance threshold, the disturbance adjustment is determined to be an effective boost direction disturbance, and thus, in subsequent steps, it is combined with acceleration change rate data. The influence of pressure-boosting directional disturbance on the braking response of the target vehicle is determined by the trend of road surface adhesion coefficient change.

[0122] S43, When the disturbance braking pressure data P b 'Less than the current braking pressure data P' b When the absolute value of the difference in braking pressure disturbance is greater than the preset pressure disturbance threshold, the direction of braking pressure disturbance is determined to be the decompression direction.

[0123] In this embodiment, the decompression direction refers to the disturbance braking pressure data P. b 'Relative to the current braking pressure data P b The direction of decrease, and the preset pressure disturbance threshold are used to determine the disturbance braking pressure data P. b 'Compared with current brake pressure data P b Whether the pressure difference between them reaches the effective disturbance range.

[0124] Specifically, when the disturbance braking pressure data P b 'Less than the current braking pressure data P' b Furthermore, if the absolute value of the braking pressure disturbance difference is greater than the preset pressure disturbance threshold, the disturbance adjustment is determined to be an effective pressure reduction directional disturbance, and thus, in subsequent steps, it is combined with acceleration change rate data. The influence of pressure relief directional disturbance on the braking response of the target vehicle is determined by the trend of road surface adhesion coefficient change.

[0125] In one embodiment, in step S40, the operating point position state includes at least a stable region state, a dead-end trend region state, and a state near the peak, based on acceleration rate of change data. The direction of braking pressure disturbance and the trend of road surface adhesion coefficient changes are used to determine the target vehicle's operating point position and status within the current braking cycle, specifically including:

[0126] S44. If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data... If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point location is determined to be in a stable zone.

[0127] In this embodiment, the stable zone state refers to the state where the current braking point is located to the left of the peak value of the road surface adhesion coefficient. In the stable zone state, the pressure boosting direction disturbance can increase the absolute value of the vehicle's longitudinal acceleration and increase the road surface adhesion coefficient.

[0128] Specifically, when the direction of the braking pressure disturbance is the direction of pressure increase, the acceleration change rate data... When the pressure is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, the pressure disturbance in the direction of pressure increase is determined to enhance the braking response of the target vehicle and cause the road surface adhesion coefficient to change in the increasing direction. Thus, it is determined that the current braking working point has not yet exceeded the peak value of the road surface adhesion coefficient, and the working point position state is determined to be the stable zone state.

[0129] S45. If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data... If the value is less than zero and the trend of the road surface adhesion coefficient is decreasing, then the working point location state is determined to be in the dead zone state.

[0130] In this embodiment, the lock-up tendency zone state refers to the state where the current braking point is located to the right of the peak value of the road adhesion coefficient. In the lock-up tendency zone state, continuing to increase the pressure will reduce the absolute value of the longitudinal acceleration of the whole vehicle and reduce the road adhesion coefficient.

[0131] Specifically, when the direction of the braking pressure disturbance is the direction of pressure increase, the acceleration change rate data... When the pressure is less than zero and the road surface adhesion coefficient changes in a decreasing trend, the pressure disturbance in the direction of pressure increase weakens the braking response of the target vehicle and causes the road surface adhesion coefficient to change in a decreasing direction. Thus, it is determined that the current braking working point has passed the peak value of the road surface adhesion coefficient, and the working point position state is determined to be the lock-up trend zone state.

[0132] S46. If the direction of the braking pressure disturbance is the direction of decompression, and the acceleration change rate data... If the value is less than zero and the trend of the road surface adhesion coefficient is a decreasing trend, then the working point location is determined to be in a stable zone.

[0133] In this embodiment, the stable region state can also be determined by the response change under decompression direction disturbance, wherein the decompression direction disturbance refers to the pressure disturbance formed when the disturbance braking pressure data is less than the current braking pressure data.

[0134] Specifically, when the direction of the braking pressure disturbance is the direction of decompression, the acceleration change rate data... When the pressure is less than zero and the road surface adhesion coefficient changes in a decreasing trend, the pressure disturbance in the direction of pressure reduction weakens the braking response of the target vehicle and causes the road surface adhesion coefficient to change in a decreasing direction. Thus, the current braking working point is determined to be to the left of the peak value of the road surface adhesion coefficient. In this position, reducing the braking pressure will cause the braking response and the road surface adhesion coefficient to decrease synchronously. Therefore, the working point position is determined to be in the stable zone.

[0135] S47. If the direction of the braking pressure disturbance is the direction of decompression, and the acceleration rate of change data... If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point location state is determined to be the dead-lock trend zone state.

[0136] In this embodiment, the lock-up trend zone state can also be determined by the response change under decompression direction disturbance, wherein the lock-up trend zone state corresponds to the state where the current braking operating point has exceeded the peak value of the road surface adhesion coefficient.

[0137] Specifically, when the direction of the braking pressure disturbance is the direction of decompression, the acceleration change rate data... When the pressure is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, the pressure disturbance in the direction of pressure reduction enhances the braking response of the target vehicle and causes the road surface adhesion coefficient to change in the increasing direction. Thus, the current braking operating point is determined to be to the right of the peak value of the road surface adhesion coefficient. In this position, reducing the braking pressure can cause the braking operating point to return to the direction of the peak value of the road surface adhesion coefficient. Therefore, the operating point position is determined to be the lock-up trend zone state.

[0138] S48. If the acceleration rate of change data If the absolute value of the coefficient of friction is less than the preset rate of change threshold, and the trend of the coefficient of friction is a stable trend, then the working point position is determined to be near the peak value.

[0139] In this embodiment, the near-peak state refers to the state where the current braking operating point is close to the peak value of the road adhesion coefficient. In the near-peak state, the absolute value of the vehicle's longitudinal acceleration changes little before and after the disturbance adjustment, and the road adhesion coefficient changes little.

[0140] Specifically, when the acceleration rate of change data When the absolute value of the road surface adhesion coefficient is less than the preset rate of change threshold and the road surface adhesion coefficient changes in a stable trend, it is determined that the absolute value of the longitudinal acceleration of the vehicle before and after the disturbance adjustment is within a stable range, and the road surface adhesion coefficient before and after the disturbance adjustment is within a stable range. Thus, it is determined that the current braking working point is near the peak value of the road surface adhesion coefficient, and the working point position state is determined to be near the peak value state.

[0141] In one embodiment, in step S50, the brake pressure adjustment command includes at least a pressure increase command, a pressure decrease command, and a pressure holding command. Based on the operating point position state, a brake pressure adjustment command for the current braking cycle is generated, specifically including:

[0142] S51. When the working point position is in the stable zone, a boost command is generated. The boost command is used to increase the braking pressure of the target vehicle in the current braking cycle.

[0143] In this embodiment, the boost command refers to the command used to control the valve body to increase the current braking pressure of the target vehicle, and the stable zone state corresponds to the state where the current braking working point is located to the left of the peak value of the road surface adhesion coefficient.

[0144] Specifically, when the working point position is in a stable state, a boost command is generated and sent to the valve body, causing the valve body to increase the braking pressure of the target vehicle in the current braking cycle, thereby causing the braking working point in the next braking cycle to move towards the peak value of the road adhesion coefficient.

[0145] S52. When the working point position is in the lock-up trend zone, a decompression command is generated. The decompression command is used to reduce the braking pressure of the target vehicle in the current braking cycle.

[0146] In this embodiment, the pressure reduction command refers to the command used to control the valve body to reduce the current braking pressure of the target vehicle, and the lock-up trend zone state corresponds to the state where the current braking operating point is located to the right of the peak value of the road surface adhesion coefficient.

[0147] Specifically, when the working point position is in the lock-up trend zone, a pressure reduction command is generated and sent to the valve body, causing the valve body to reduce the braking pressure of the target vehicle in the current braking cycle, so that the braking working point in the next braking cycle returns to the vicinity of the peak road adhesion coefficient.

[0148] S53. When the working point position is near the peak state, a pressure holding command is generated. The pressure holding command is used to maintain the braking pressure of the target vehicle in the current braking cycle.

[0149] In this embodiment, the pressure holding command refers to the command used to control the valve body to maintain the current braking pressure of the target vehicle, and the state near the peak corresponds to the state where the current braking working point is close to the peak value of the road adhesion coefficient.

[0150] Specifically, when the working point position is near the peak value, a pressure holding command is generated and sent to the valve body, so that the valve body maintains the braking pressure of the target vehicle in the current braking cycle, thereby keeping the target vehicle at the corresponding braking pressure level in the current braking state.

[0151] In one embodiment, after step S50, that is, after generating a brake pressure adjustment command for the current braking cycle based on the working point position state, the control valve body adjusts the current brake pressure of the target vehicle according to the brake pressure adjustment command, and determines whether the target vehicle meets the braking termination condition.

[0152] In this embodiment, the braking termination condition may include the target vehicle's braking pressure returning to a preset braking termination pressure range, the detection of a brake pedal release signal from the target vehicle, or the current braking pressure data being less than a preset braking pressure threshold.

[0153] Specifically, when the brake pressure adjustment command is a pressure increase command, the control valve increases the current brake pressure of the target vehicle; when the brake pressure adjustment command is a pressure decrease command, the control valve decreases the current brake pressure of the target vehicle; when the brake pressure adjustment command is a pressure hold command, the control valve maintains the current brake pressure of the target vehicle. After the valve completes the brake pressure adjustment within the current braking cycle, if the target vehicle does not meet the braking termination condition, the next braking cycle begins, and the current longitudinal acceleration data and current brake pressure data for the next braking cycle are reacquired. The steps of determining disturbance brake pressure data, adjusting disturbance brake pressure, determining acceleration rate of change data, determining the trend of road adhesion coefficient change, determining the working point position state, and generating brake pressure adjustment commands are then executed. If the target vehicle meets the braking termination condition, the generation of disturbance brake pressure adjustment commands and brake pressure adjustment commands is stopped, causing the anti-lock braking control method to exit the current braking process.

[0154] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0155] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An anti-lock braking control method without wheel speed sensors, characterized in that, An anti-lock braking system (ABS) including an electronic control unit and a valve body, wherein the electronic control unit has a built-in vehicle acceleration sensor and the valve body has a built-in hydraulic pressure sensor, and the ABS control method includes: During the braking process of the target vehicle, the current longitudinal acceleration data a of the target vehicle in the current braking cycle is acquired. x And current braking pressure data P b ; According to the current braking pressure data P b Determine the disturbance braking pressure data P b The system generates a disturbance braking pressure adjustment command, which controls the valve body to adjust the pressure according to the disturbance braking pressure data P. b 'Perform disturbance adjustment on the current braking pressure of the target vehicle;' Based on the vehicle longitudinal acceleration data before and after the disturbance adjustment, determine the acceleration change rate data. and the trend of changes in road surface adhesion coefficient; Based on the current braking pressure data P b and the disturbance braking pressure data P b ', determine the direction of the braking pressure disturbance, and based on the acceleration change rate data. The direction of the braking pressure disturbance and the trend of the road surface adhesion coefficient are used to determine the working point position of the target vehicle in the current braking cycle. Based on the working point position state, a brake pressure adjustment command is generated for the current braking cycle, wherein the brake pressure adjustment command is used to adjust the current brake pressure of the target vehicle.

2. The anti-lock braking control method according to claim 1, characterized in that, During the braking process of the target vehicle, the current longitudinal acceleration data a of the target vehicle in the current braking cycle is acquired. x And current braking pressure data P b Specifically, it includes: When the braking pressure of the target vehicle is detected to be generated or changed, it is determined that the target vehicle has entered the current braking cycle; During the current braking cycle, the initial longitudinal acceleration data a of the vehicle is acquired by the vehicle acceleration sensor. x0 And the initial braking pressure data P acquired through the oil pressure sensor. b0 ; The initial longitudinal acceleration data a of the whole vehicle were respectively... x0 and the initial braking pressure data P b0 After filtering, the current longitudinal acceleration data a of the whole vehicle is obtained. x and the current braking pressure data P b .

3. The anti-lock braking control method according to claim 1, characterized in that, The method based on the current braking pressure data P b Determine the disturbance braking pressure data P b Specifically, it includes: Obtain preset disturbance signal parameters, wherein the disturbance signal parameters include at least disturbance amplitude parameters and disturbance frequency parameters; A pressure disturbance signal is generated based on the disturbance amplitude parameter and the disturbance frequency parameter; The current braking pressure data P b The disturbance braking pressure data P is obtained by superimposing the disturbance signal with the disturbance signal. b '.

4. The anti-lock braking control method according to claim 3, characterized in that, The disturbance braking pressure data is based on formula P. b '=P b +A·sin(ωt) is determined, where P b 'P' represents the disturbance braking pressure data. b Here, A is the current braking pressure data, ω is the disturbance amplitude parameter, t is the disturbance frequency parameter, and t is the current time corresponding to the current braking cycle. The value range of the disturbance amplitude parameter is 0.1MPa to 0.5MPa, and the value range of the disturbance frequency parameter is 2Hz to 20Hz.

5. The anti-lock braking control method according to claim 1, characterized in that, The acceleration change rate data is determined based on the vehicle longitudinal acceleration data before and after the disturbance adjustment. And the trend of changes in road surface adhesion coefficient, specifically including: Acquire the longitudinal acceleration data a of the target vehicle after disturbance during the current braking cycle. x Based on the current longitudinal acceleration data of the whole vehicle a x The absolute value of the longitudinal acceleration data of the whole vehicle after the disturbance, a x The acceleration change rate data is calculated by taking the absolute value of ' and the corresponding control cycle time interval. ; Based on the current vehicle longitudinal acceleration data a x Estimate the current road surface adhesion coefficient μ, and based on the longitudinal acceleration data a of the vehicle after the disturbance. x 'Estimate the road surface adhesion coefficient μ after disturbance'; The current road surface adhesion coefficient μ and the road surface adhesion coefficient μ' after disturbance are compared to determine the trend of road surface adhesion coefficient change. The trend of road surface adhesion coefficient change includes an increasing trend of road surface adhesion coefficient, a decreasing trend of road surface adhesion coefficient, and a stable trend of road surface adhesion coefficient.

6. The anti-lock braking control method according to claim 5, characterized in that, The calculation process for the road surface adhesion coefficient specifically includes: Obtain the vehicle dynamics parameters of the target vehicle, wherein the vehicle dynamics parameters include at least the total vehicle mass and wheel vertical load; Based on the vehicle's longitudinal acceleration data, the vehicle's total mass, and the wheel's vertical load, the formula μ=(|a|·M) / F is used. z The corresponding road surface adhesion coefficient is calculated, where μ is the road surface adhesion coefficient, |a| is the absolute value of the vehicle's longitudinal acceleration data, M is the total mass of the vehicle, and F... z The vertical load on the wheel is given.

7. The anti-lock braking control method according to claim 6, characterized in that, The data based on the current braking pressure P b and the disturbance braking pressure data P b Determine the direction of the braking pressure disturbance, specifically including: The disturbance braking pressure data P b 'Compared with the current braking pressure data P b By comparing the values, the difference in braking pressure disturbance is obtained; When the disturbance braking pressure data P b 'Greater than the current braking pressure data P' b When the absolute value of the brake pressure disturbance difference is greater than the preset pressure disturbance threshold, the direction of the brake pressure disturbance is determined to be the pressure boosting direction. When the disturbance braking pressure data P b 'Less than the current braking pressure data P' b When the absolute value of the braking pressure disturbance difference is greater than the preset pressure disturbance threshold, the braking pressure disturbance direction is determined to be the decompression direction.

8. The anti-lock braking control method according to claim 7, characterized in that, The operating point position state includes at least the stable region state, the dead-end trend region state, and the state near the peak, based on the acceleration change rate data. The direction of the braking pressure disturbance and the trend of the road surface adhesion coefficient are used to determine the operating point position of the target vehicle within the current braking cycle, specifically including: If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point position state is determined to be the stable zone state. If the direction of the braking pressure disturbance is the direction of pressure increase, and the acceleration change rate data If the value is less than zero and the trend of the road surface adhesion coefficient is a decreasing trend, then the working point position state is determined to be the lock-up trend zone state. If the direction of the braking pressure disturbance is the decompression direction, and the acceleration change rate data If the value is less than zero and the trend of the road surface adhesion coefficient is a decreasing trend, then the working point position state is determined to be the stable zone state. If the direction of the braking pressure disturbance is the decompression direction, and the acceleration change rate data If the value is greater than zero and the trend of the road surface adhesion coefficient is an increasing trend, then the working point position state is determined to be the lock-up trend zone state. If the acceleration change rate data If the absolute value of the road surface adhesion coefficient is less than the preset rate of change threshold, and the trend of the road surface adhesion coefficient change is a stable trend, then the working point position state is determined to be near the peak value.

9. The anti-lock braking control method according to claim 8, characterized in that, The brake pressure adjustment command includes at least a pressure increase command, a pressure decrease command, and a pressure hold command. The generation of the brake pressure adjustment command for the current braking cycle based on the operating point position state specifically includes: When the working point position is in the stable zone state, the boost command is generated, and the boost command is used to increase the braking pressure of the target vehicle in the current braking cycle; When the working point position is in the lock-up tendency zone state, the decompression command is generated, and the decompression command is used to reduce the braking pressure of the target vehicle in the current braking cycle; When the operating point position is near the peak value, the pressure holding command is generated to maintain the braking pressure of the target vehicle during the current braking cycle.

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