Vehicle braking curve calibration method and device

Abstract

The invention discloses a braking curve calibration method and device for a vehicle, an initial clamping stroke corresponding to a target clamping force is determined based on an initial curve, the initial clamping stroke is compensated according to the difference between vehicle deceleration to obtain a target clamping stroke, and the target clamping stroke can be used for controlling the vehicle to brake. Based on this, the target clamping stroke obtained through compensation is more accurate than the initial clamping stroke. If it is determined that the target clamping force and the target clamping stroke meet the stable conditions, the target clamping force and the target clamping stroke are constructed into a calibration data pair. Next, curve fitting can be carried out according to the multiple calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle, and compared with an initial curve, the target curve can more accurately reflect the corresponding relation between the clamping force and the clamping stroke; the target curve is obtained, namely calibration of the braking curve of the vehicle is completed, and then the target curve can be used for conducting braking control over the vehicle more accurately.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a method and device for calibrating a braking curve of a vehicle. Background Art

[0002] The development of vehicle braking systems can be divided into three stages. The first stage is pure mechanical braking, where the braking energy is completely provided by the human body. The cars at this stage are small in mass and slow in speed, so the braking force requirements are not high. Relying on a pure mechanical braking system is sufficient to meet the braking requirements. The second stage is pressure braking, including hydraulic braking and pneumatic braking, such as the Electro Hydraulic Brake (EHB). At this stage, the car mass is getting larger and the speed is getting faster, which requires higher and higher braking systems. Therefore, it is necessary to use related power-assisting devices (such as vacuum boosters) to help the driver provide greater braking force. The third stage, which is currently developing rapidly, is the wire control brake system. The braking system at this stage is not only to meet the braking performance requirements, but more to pursue high efficiency, reliability, integration and other characteristics, and also provide more possibilities for intelligent driving.

[0003] In the wire control brake system, braking can be achieved based on the Electro Mechanical Brake (EMB). Specifically, after the EMB receives the clamping force request sent by the upper controller (for example, the vehicle controller), it uses its internal motor to provide power and drives the clamping caliper through the internal mechanical mechanism to form a certain clamping stroke, clamp the wheel brake disc, slow down the wheel, and finally generate vehicle braking force to achieve braking.

[0004] However, in the related art, when the EMB responds to the clamping force request to form the tightening stroke, there is a problem of poor control accuracy, which makes it difficult to provide stable braking service. Summary of the invention

[0005] In order to solve the above technical problems, the present application provides a vehicle braking curve calibration method and device to determine the target curve between the vehicle's clamping force and clamping stroke. Compared with the initial curve, the target curve can more accurately reflect the correspondence between the clamping force and the clamping stroke.

[0006] The embodiments of the present application disclose the following technical solutions:

[0007] On the one hand, an embodiment of the present application provides a method for calibrating a braking curve of a vehicle, the method comprising:

[0008] In response to a first clamping force request for the vehicle, determining an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between clamping force and clamping stroke;

[0009] According to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, the initial clamping stroke is compensated to obtain a target clamping stroke corresponding to the target clamping force; the target clamping stroke is used to control the vehicle to brake;

[0010] If it is determined that the target clamping force and the target clamping stroke meet a stability condition, constructing the target clamping force and the target clamping stroke into a calibration data pair;

[0011] Performing curve fitting according to a plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle;

[0012] When a second clamping force request for the vehicle is received, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request is determined according to the target curve, and the brake clamping stroke is used to control the vehicle to brake.

[0013] On the other hand, an embodiment of the present application provides a braking curve calibration device for a vehicle, the device comprising a determination unit, a compensation unit, a construction unit and a fitting unit:

[0014] The determining unit is configured to determine, in response to a first clamping force request for the vehicle, an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between the clamping force and the clamping stroke;

[0015] The compensation unit is used to compensate the initial clamping stroke according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, so as to obtain a target clamping stroke corresponding to the target clamping force; the target clamping stroke is used to control the vehicle to brake;

[0016] The construction unit is used to construct the target clamping force and the target clamping stroke into a calibration data pair if it is determined that the target clamping force and the target clamping stroke meet a stability condition;

[0017] The fitting unit is used to perform curve fitting according to a plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle;

[0018] The determination unit is further configured to determine, when receiving a second clamping force request for the vehicle, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request according to the target curve, wherein the brake clamping stroke is used to control the vehicle to brake.

[0019] It can be seen from the above technical solution that in response to the first clamping force request for the vehicle, the initial clamping stroke corresponding to the target clamping force in the first clamping force request can be determined according to the initial curve between the clamping force and the clamping stroke. Then, the initial clamping stroke can be compensated according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the actual value of the vehicle deceleration, and the target clamping stroke corresponding to the target clamping force can be obtained, and the target clamping stroke can be used to control the vehicle for braking. Among them, the difference can be used to reflect the difference between the actual deceleration situation and the theoretical deceleration situation. Based on this, the compensation is performed, and the target clamping stroke obtained can more accurately control the vehicle for braking compared with the initial clamping stroke, so that the actual deceleration situation is close to the theoretical deceleration situation. If it is determined that the target clamping force and the target clamping stroke meet the stability condition, it means that the two are stable. At this time, the state of the vehicle's braking system is basically stable, so the target clamping force and the target clamping stroke can be constructed as a calibration data pair. Next, a target curve between the clamping force and the clamping stroke of the vehicle can be obtained by curve fitting based on multiple calibration data pairs. The target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke than the initial curve. Obtaining the target curve means completing the calibration of the vehicle's braking curve, and then the target curve can be used to guide the vehicle's braking process. Specifically, when a second clamping force request for the vehicle is received, the brake clamping stroke corresponding to the brake clamping force in the second clamping force request can be determined based on the target curve, and the brake clamping stroke can be used to control the vehicle to brake. Since the target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke, the brake clamping stroke determined based on the target curve can more accurately control the vehicle's braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram of an EMB controller structure provided in an embodiment of the present application;

[0022] Figure 2A schematic diagram of another EMB controller structure provided in an embodiment of the present application;

[0023] Figure 3 A flow chart of a vehicle braking curve calibration method provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of a curve fitting provided in an embodiment of the present application;

[0025] Figure 5 A schematic diagram of the architecture of a braking curve calibration system provided in an embodiment of the present application;

[0026] Figure 6 A structural diagram of a vehicle braking curve calibration device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0028] In the wire-controlled braking system, braking can be achieved based on EMB. Specifically, after the EMB receives the clamping force request sent by the upper controller (for example, the vehicle controller), it uses its internal motor to provide power and drives the clamping caliper through the internal mechanical mechanism to form a certain clamping stroke, clamping the wheel brake disc, so that the wheel slows down, and finally generates vehicle braking force to achieve braking.

[0029] Most existing EMBs include clamping force sensors. For details, please refer to Figure 1 As shown, the clamping force sensor is mainly used to collect the clamping force of the caliper, so as to perform closed-loop control on the clamping force, such as Figure 1 The structure of the EMB controller including the clamping force closed loop is described. However, due to factors such as possible installation deviation of the clamping force sensor and coaxial deviation of the EMB assembly, the actual brake caliper clamping force cannot be correctly fed back, which ultimately leads to the EMB being unable to complete the clamping force requested by the upper control layer, or there are differences between EMBs on the same vehicle. In addition, from the perspective of cost and reliability, the clamping force sensor also tends to be gradually eliminated. Therefore, how to control the EMB actuator so that it can accurately apply the clamping force becomes an important issue.

[0030] In the scenario where the clamping force sensor is not installed, since there is no clamping force feedback, the EMB itself can only perform open-loop control of the clamping force, that is, according to the requested clamping force, look up a table (usually a scatter table) or an initial curve (the initial curve can be drawn based on the scatter table) to obtain the clamping stroke of the EMB clamping transmission mechanism. For details, please refer to Figure 2 As shown. Although the stroke of the EMB internal transmission mechanism can be precisely controlled, the relationship curve between the stroke and the clamping force cannot be completely accurate due to the aforementioned deviation. Usually, the initial curve, i.e., the value in the scatter table, is determined by engineers based on experience. As the vehicle mileage increases, the EMB internal transmission mechanism will also experience certain wear, which will also introduce deviations.

[0031] It can be seen that in the related art, when the EMB responds to the clamping force request to form the tightening stroke, there is a problem of poor control accuracy, which makes it difficult to provide stable braking service.

[0032] To this end, the present application provides a vehicle braking curve calibration method and device, which calibrates a target curve that is more accurate than an initial curve to achieve more precise braking control.

[0033] The vehicle braking curve calibration method provided in the embodiment of the present application can be implemented by a computer device, which can be a terminal device or a server, wherein the server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing cloud computing services. The terminal device includes but is not limited to mobile phones, computers, intelligent voice interaction devices, smart home appliances, vehicle-mounted terminals, etc. The terminal device and the server can be directly or indirectly connected via wired or wireless communication, and this application does not impose any restrictions on this.

[0034] The specific examples are as follows:

[0035] Figure 3 A flowchart of a vehicle braking curve calibration method provided in an embodiment of the present application is provided, and a server is used as the aforementioned computer device as an example for explanation. The method includes S301-S305:

[0036] S301: In response to a first clamping force request for a vehicle, determine an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between clamping force and clamping stroke.

[0037] The first clamping force request may be initiated by the vehicle when braking is required, and the first clamping force request may be sent by the upper controller to the clamping force control module (such as the EMB clamping force control module), and may be based on an initial curve between the clamping force and the clamping stroke (for example, Figure 2 The initial clamping stroke corresponding to the target clamping force in the first clamping force request is determined, the target clamping force may refer to the clamping force currently requested, corresponding to the horizontal axis in the initial curve, and the initial clamping stroke may refer to the value of the vertical axis corresponding to the target clamping force in the initial curve, representing the stroke request value.

[0038] S302: Compensating the initial clamping stroke according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, to obtain a target clamping stroke corresponding to the target clamping force.

[0039] Due to the inaccuracy of the initial curve, the initial clamping stroke may be biased, making it difficult to meet the braking demand corresponding to the target clamping force. Therefore, the initial clamping stroke can be compensated according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the actual value of the vehicle deceleration, and the target clamping stroke corresponding to the target clamping force can be obtained. Among them, the difference can be used to reflect the difference between the actual deceleration situation and the theoretical deceleration situation. Based on this, the compensation is performed, and the target clamping stroke obtained can more accurately control the vehicle for braking compared to the initial clamping stroke, so that the actual deceleration situation is close to the theoretical deceleration situation. After determining the target clamping stroke, the target clamping stroke can be used to control the vehicle for braking. Usually, the target clamping stroke can be sent to the underlying controller of the EMB to realize the control of the clamping stroke according to the target clamping stroke, so as to respond to the braking demand of the vehicle.

[0040] It should be noted that the present application does not impose any limitation on how to compensate for the difference. For ease of understanding, the present application provides the following methods as examples:

[0041] In a possible implementation, a compensation stroke may be determined based on the difference between the vehicle deceleration request value and the vehicle deceleration actual value, and the compensation stroke may represent the clamping stroke required to compensate for the difference between the decelerations. Then, a target clamping stroke may be determined based on the initial clamping stroke and the compensation stroke. Based on this, compensation is implemented based on the method of determining the compensation stroke to obtain the target clamping stroke.

[0042] In practical applications, the aforementioned difference can be the difference between the vehicle deceleration request value and the vehicle deceleration actual value. In the present application, the deceleration value is defined as being greater than zero when the vehicle and wheel speeds decrease. Therefore, if the difference is greater than zero, the clamping stroke can be increased (the clamping force is increased so that the actual clamping force is close to the requested target clamping force), and accordingly, the target clamping stroke is greater than the initial clamping stroke. If the difference is less than zero, the clamping stroke can be reduced (the clamping force is reduced so that the actual clamping force is close to the requested target clamping force), and accordingly, the target clamping stroke is less than the initial clamping stroke. If the difference is equal to zero, the target clamping stroke is equal to the initial clamping stroke. In specific implementation, if the difference is greater than zero, it can be determined that the compensation stroke is greater than zero, so as to achieve the purpose of increasing the clamping stroke and achieve compensation, and vice versa.

[0043] It should be noted that the present application does not make any limitation on how to determine the compensation stroke based on the difference. For ease of understanding, the present application provides the following methods as examples:

[0044] In a possible implementation, a proportional-integral control algorithm can be used to perform proportional-integral control on the difference to determine the compensation stroke. In specific implementation, it can be determined by the following formula:

[0045]

[0046] In the above formula, can represent the compensation stroke, e can represent the difference, K p and K i Can represent the proportional coefficient and integral coefficient in the proportional-integral control algorithm respectively, K p and K i Both are greater than zero.

[0047] In practical applications, K p and K i It can be preset or flexibly adjusted according to actual conditions. And, the aforementioned difference can be determined by the following formula:

[0048]

[0049] In the above formula, e can represent the difference, Can represent the vehicle deceleration request value, a w It can represent the real value of vehicle deceleration. In practical applications, the real value of vehicle deceleration can be the real value of wheel deceleration collected.

[0050] Accordingly, the target clamping stroke can be determined by the following formula:

[0051]

[0052] In the above formula, The target clamping stroke can be indicated. It can represent the initial clamping stroke, Can indicate compensation travel.

[0053] S303: If it is determined that the target clamping force and the target clamping stroke meet the stability condition, the target clamping force and the target clamping stroke are constructed as a calibration data pair.

[0054] In the present application, the aforementioned target clamping force and target clamping stroke are collected during the actual vehicle process, that is, the calibration of the braking curve based on the actual vehicle data in the present application is implemented, which is conducive to improving the accuracy of the application of the calibrated target curve in the actual vehicle. In practical applications, in order to improve the accuracy, the collected data is screened to a certain extent to ensure the accuracy of the data used for the calibration of the braking curve, thereby improving the accuracy of the target curve. Specifically, if it is determined that the target clamping force and the target clamping stroke meet the stability conditions, it indicates that the stable state is met, that is, the braking control is performed based on the target clamping stroke, and the braking can be stably achieved. At this time, the target clamping force and the target clamping stroke can be constructed as a calibration data pair. Among them, the stability condition is related to the process of controlling the vehicle to brake according to the target clamping stroke.

[0055] It should be noted that the present application does not make any limitation on the setting of the stability condition, that is, how to determine the target clamping force and the target clamping stroke to meet the stability condition. For ease of understanding, the present application provides the following methods as examples:

[0056] In one possible implementation, if, within a continuous preset time period, the fluctuation value of the target clamping force is less than or equal to a first threshold, the fluctuation value of the target clamping stroke is less than or equal to a second threshold, and the fluctuation value of the vehicle's deceleration is less than or equal to a third threshold, then it can be determined that the target clamping force and the target clamping stroke meet stability conditions.

[0057] Based on the above embodiments, the determination of the calibration data pair is illustrated. For better understanding, the present application embodiment further provides the following examples for determining the stability conditions of the above examples:

[0058] During the vehicle braking process, data sampling can be performed, and then the data that meets the stability conditions can be selected to construct a calibration data pair. Specifically, real-time data will be generated at each sampling time t=0, Δt, 2Δt, ... Among them, the data that needs to be collected includes the vehicle deceleration request value and the current actual wheel deceleration a w,t The error between t , the clamping force request value issued by the upper controller (i.e., the target clamping force corresponding to the sampling time t), the actual value of the EMB transmission mechanism stroke D t (i.e. the actual value of the clamping stroke corresponding to the sampling time t). The main purpose is to filter the real-time data according to the given conditions to obtain the data that can be used by the subsequent modules. The specific filtering conditions are that the following items are met at the same time and continuously met after a given time T (i.e. the system state is basically stable):

[0059] On the one hand, the clamping force request value issued by the upper controller Basically stable, that is, the fluctuation value of the aforementioned target clamping force is less than or equal to the first threshold value, which can be specifically expressed by the following formula:

[0060]

[0061] In the above formula, For the time interval [tT, t] The maximum value of For the time interval [tT, t] The minimum value of ε F >0 is a given threshold value, namely, the first threshold value.

[0062] On the other hand, the actual value D of the EMB transmission mechanism stroke t Basically stable, that is, the fluctuation value of the aforementioned target clamping stroke is less than or equal to the second threshold value, which can be specifically expressed by the following formula:

[0063] D max -D min ≤ε D

[0064] In the above formula, D max D in the time interval [tT, t] t The maximum value, D min D in the time interval [tT, t] t The minimum value of ε D >0 is a given threshold value, namely, the second threshold value.

[0065] On the other hand, the absolute value of the error between the wheel deceleration and the vehicle deceleration is less than or equal to the given threshold value, that is, the deceleration fluctuation value of the vehicle is less than or equal to the third threshold value, which can be specifically expressed by the following formula:

[0066] |e t |≤ε e

[0067] In the above formula, e t It can represent the vehicle's deceleration fluctuation value, ε e >0, indicating the third threshold.

[0068] In practical applications, the above data sampling and data filtering can be implemented through the data filtering module to construct calibration data pairs. Usually, the data that meets the above stability conditions can be filtered and stored in the vehicle controller memory in the form of calibration data pairs for subsequent calibration. For example, it can be stored as in, It can represent the target clamping force in the kth calibration data pair, D k The target clamping stroke in the kth calibration data pair can be represented.

[0069] S304: Performing curve fitting according to the plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle.

[0070] After constructing multiple calibration data pairs (such as the K calibration data pairs mentioned above), curve fitting can be performed to obtain a target curve between the clamping force and the clamping stroke of the vehicle. The target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke than the initial curve. Obtaining the target curve means completing the calibration of the vehicle's braking curve, and then the target curve can be used to guide the vehicle's braking process.

[0071] It should be noted that the present application does not impose any limitation on how to perform curve fitting to obtain the target curve. For ease of understanding, the present application provides the following methods as examples:

[0072] It is understandable that multiple calibration data pairs are also distributed as multiple points in a rectangular coordinate system with clamping force as the horizontal coordinate and clamping stroke as the vertical coordinate. In order to achieve more precise fitting, in a possible implementation, multiple calibration data pairs can be divided into multiple calibration data groups according to the magnitudes of multiple target clamping forces included in the multiple calibration data pairs. Then, a calibration curve can be obtained by curve fitting based on the calibration data pairs included in a calibration data group. Correspondingly, multiple calibration data groups can fit multiple calibration curves. In order to ensure the continuity of the obtained target curve, for the connection points of two adjacent calibration curves, the connection points correspond to the same clamping force and clamping stroke on the two calibration curves. Finally, the target curve can be determined based on the calibration curves corresponding to the multiple calibration data groups.

[0073] For a better understanding, see Figure 4 As shown, multiple calibration data pairs take the aforementioned K calibration data pairs as an example. The calibration data pairs can be found in Figure 4 In the example, the K calibration data pairs are multiple points distributed in a rectangular coordinate system with the clamping force as the horizontal coordinate and the clamping stroke as the vertical coordinate.

[0074] The present application does not limit the method of dividing the multiple calibration data groups. For ease of understanding, the present application provides the following method as an example:

[0075] In a possible implementation, the clamping force segmentation points are determined based on the initial curve, and two adjacent clamping force segmentation points are used to identify a segment of the initial curve. Figure 4 For example, six clamping force segmentation points (the first one is the coordinate origin) are determined based on the initial curve. Then, for the clamping force segmentation intervals identified by two adjacent clamping force segmentation points, a calibration data pair whose target clamping force satisfies the clamping force of the clamping force segmentation interval can be used to form a calibration data group. That is, the calibration data pairs falling into the clamping force segmentation interval constitute a calibration data group, so that the division of the calibration data group can be achieved.

[0076] In practical applications, the clamping force can be divided into segments according to the Where N represents the number of clamping force segmentation points. Figure 4 In this example, N = 6, the new data points to be stored (i.e., the aforementioned multiple calibration data pairs, see Figure 4 The fork point in the example is divided into N-1 groups according to the clamping force value, that is, N-1 calibration data groups are obtained, which can be specifically expressed by the following formula:

[0077]

[0078] In the above formula, It can represent the nth calibration data group. It can be seen that the size of the target clamping force of the calibration data pair included in the calibration data group falls within the clamping force segmentation interval corresponding to the calibration data group. The clamping force segmentation interval is marked by two adjacent clamping force segmentation points, and the two adjacent clamping force segmentation points constitute the upper and lower limits of the clamping force.

[0079] Next, a curve fitting can be performed for the specific values ​​of the calibration data pairs in each calibration data set. In a specific implementation, a piecewise linear function can be fitted, that is, multiple calibration data sets are fitted to multiple linear functions, and at the same time, the connection points of adjacent linear functions must have the same value on the two linear functions. In a possible implementation, in order to simplify the curve fitting, the aforementioned connection points and the clamping force segmentation points correspond to the same clamping force. That is, see Figure 4 For example, the connection point is the original clamping force segmentation point.

[0080] In actual fitting, in order to ensure that the connection points have the same value on the two linear functions, in a possible implementation method, the following optimization problem can be established to achieve fitting, specifically:

[0081]

[0082]

[0083] Solving the optimization problem, we obtain the piecewise linear function y=a n x+b n The coefficients in n ,b n >, n = 1, 2, ..., N-1, based on this, the function expression of each calibration curve can be obtained, and the punctuation curve can be determined accordingly. This problem belongs to a quadratic optimization problem that only contains equality constraints. It has a unique optimal solution, and the calculation amount required for solving it is small. It can realize curve fitting simply and quickly, which is conducive to improving the calibration efficiency.

[0084] After completing the curve fitting, in some scenarios, if new clamping force segmentation points need to be defined for the target curve, new segmentation data points can also be obtained. Specifically, the segmentation data points are the corresponding clamping force segmentation points of each piecewise linear function. The function value obtained above can be expressed by the following formula:

[0085]

[0086] The last segmented data point is similar and is calculated using the last segment of the piecewise linear function, which can be expressed by the following formula:

[0087]

[0088] Based on this method, the horizontal coordinate of the clamping force segmentation point (i.e. the clamping force) can be kept unchanged, and the segmentation data point can be adjusted only by adjusting the value of the stroke segmentation point. Figure 4 For example, the clamping force segmentation points on the initial curve before calibration and the target curve after calibration correspond to the same clamping force value, but the clamping stroke value is different. It is understandable that the new clamping force segmentation point can also be determined by controlling the ordinate value of the clamping force segmentation point to remain unchanged and adjusting the abscissa value.

[0089] S305: When a second clamping force request for the vehicle is received, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request is determined according to the target curve.

[0090] ​After the target curve is calibrated, the calibration of the vehicle's braking curve is completed, and then the target curve can be used to guide the vehicle's braking process. Specifically, when a second clamping force request for the vehicle is received, the brake clamping stroke corresponding to the brake clamping force in the second clamping force request can be determined according to the target curve, and the brake clamping stroke can be used to control the vehicle to brake. Since the target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke, the brake clamping stroke determined based on the target curve can more accurately control the vehicle's braking.

[0091] For example, see Figure 4 Example, brake clamping force is If there is no newly calibrated target curve, you can only check the original initial curve to get the initial clamping stroke. However, due to inaccuracies, it is difficult to perform good brake control. However, after calibrating the target curve, a more accurate target curve can be checked to obtain the brake clamping stroke. This allows for better brake control.

[0092] In a possible implementation, the brake clamping stroke can be sent to the brake controller corresponding to the brake of the vehicle, and the brake controller can be used to control the brake according to the brake clamping stroke to achieve braking of the vehicle. Among them, the brake can be, for example, the aforementioned EMB, and the brake controller can be the bottom controller of the EMB, which controls the brake mechanism of the EMB to achieve braking. In actual use, according to the clamping force request value sent by the upper controller (i.e., the aforementioned brake clamping force), the corresponding brake clamping stroke can be obtained by linear interpolation in the target curve, and can be sent to the bottom controller of the EMB to achieve braking control.

[0093] In practical applications, the above curve fitting can be realized through the correspondence table calibration module to obtain the target curve. Through the above curve fitting process, the purpose of recalibrating the existing "clamping force-stroke correspondence table" (i.e., initial curve) based on the piecewise linear least squares algorithm is achieved to obtain the target curve.

[0094] It can be seen from the above technical solution that in response to the first clamping force request for the vehicle, the initial clamping stroke corresponding to the target clamping force in the first clamping force request can be determined according to the initial curve between the clamping force and the clamping stroke. Then, the initial clamping stroke can be compensated according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the actual value of the vehicle deceleration, and the target clamping stroke corresponding to the target clamping force can be obtained, and the target clamping stroke can be used to control the vehicle for braking. Among them, the difference can be used to reflect the difference between the actual deceleration situation and the theoretical deceleration situation. Based on this, the compensation is performed, and the target clamping stroke obtained can more accurately control the vehicle for braking compared with the initial clamping stroke, so that the actual deceleration situation is close to the theoretical deceleration situation. If it is determined that the target clamping force and the target clamping stroke meet the stability condition, it means that the two are stable. At this time, the state of the vehicle's braking system is basically stable, so the target clamping force and the target clamping stroke can be constructed as a calibration data pair. Next, a target curve between the clamping force and the clamping stroke of the vehicle can be obtained by curve fitting based on multiple calibration data pairs. The target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke than the initial curve. Obtaining the target curve means completing the calibration of the vehicle's braking curve, and then the target curve can be used to guide the vehicle's braking process. Specifically, when a second clamping force request for the vehicle is received, the brake clamping stroke corresponding to the brake clamping force in the second clamping force request can be determined based on the target curve, and the brake clamping stroke can be used to control the vehicle to brake. Since the target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke, the brake clamping stroke determined based on the target curve can more accurately control the vehicle's braking.

[0095] For better understanding, the present application also provides the following examples: Figure 5 The schematic diagram of the braking curve calibration system shown in the figure is as follows:

[0096] The EMB clamping force control module can directly interact with the EMB and receive the first clamping force request sent by the upper-level controller. The first clamping force request includes a target clamping force and can input the actual value of the wheel deceleration (i.e., the aforementioned actual value of the vehicle deceleration). The module determines the aforementioned initial clamping stroke based on the target clamping force and the initial curve, compensates based on the difference, obtains the target clamping stroke, and sends it to the bottom-level controller of the EMB to control the EMB stroke controller and the actuator to achieve braking.

[0097] The data screening module can be used to implement the aforementioned data sampling and data screening and construct calibration data pairs.

[0098] The data storage device can be used to store calibration data pairs for calibration calls.

[0099] The correspondence table calibration module can be used to implement the aforementioned curve fitting and obtain the target curve.

[0100] It can be understood that it basically corresponds to the method embodiment, so the relevant parts can refer to the partial description of the method embodiment.

[0101] Figure 6 This is a structural diagram of a vehicle braking curve calibration device provided in an embodiment of the present application, wherein the device includes a determination unit 601, a compensation unit 602, a construction unit 603, and a fitting unit 604:

[0102] The determining unit 601 is configured to determine, in response to a first clamping force request for the vehicle, an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between the clamping force and the clamping stroke;

[0103] The compensation unit 602 is used to compensate the initial clamping stroke according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, so as to obtain a target clamping stroke corresponding to the target clamping force; the target clamping stroke is used to control the vehicle to brake;

[0104] The construction unit 603 is used to construct the target clamping force and the target clamping stroke into a calibration data pair if it is determined that the target clamping force and the target clamping stroke meet a stability condition;

[0105] The fitting unit 604 is used to perform curve fitting according to a plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle;

[0106] The determination unit 601 is further configured to determine, when receiving a second clamping force request for the vehicle, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request according to the target curve, wherein the brake clamping stroke is used to control the vehicle to brake.

[0107] In a possible implementation manner, the fitting unit is further configured to:

[0108] Dividing the plurality of calibration data pairs into a plurality of calibration data groups according to the magnitudes of a plurality of target clamping forces included in the plurality of calibration data pairs;

[0109] According to the calibration data pairs included in a calibration data group, curve fitting is performed to obtain a calibration curve; for the connection points of two adjacent calibration curves, the connection points correspond to the same clamping force and clamping stroke on the two calibration curves;

[0110] The target curve is determined according to the calibration curves respectively corresponding to the multiple calibration data groups.

[0111] In a possible implementation manner, the fitting unit is further configured to:

[0112] Obtaining and determining the clamping force segmentation points according to the initial curve; two adjacent clamping force segmentation points are used to identify a section of the curve on the initial curve;

[0113] For the clamping force segmentation interval marked by two adjacent clamping force segmentation points, a calibration data pair in which the target clamping force satisfies the clamping force in the clamping force segmentation interval is used to form a calibration data group.

[0114] In a possible implementation manner, the connection point and the clamping force segmentation point correspond to the same clamping force.

[0115] In a possible implementation manner, the compensation unit is further configured to:

[0116] determining a compensation stroke based on a difference between the vehicle deceleration request value and the vehicle deceleration actual value;

[0117] The target clamping stroke is determined based on the initial clamping stroke and the compensation stroke.

[0118] In a possible implementation manner, the compensation unit is further configured to:

[0119] The difference is subjected to proportional-integral control using a proportional-integral control algorithm to determine the compensation stroke.

[0120] In one possible implementation, the difference is the difference between the vehicle deceleration request value and the vehicle deceleration actual value. If the difference is greater than zero, the target clamping stroke is greater than the initial clamping stroke. If the difference is less than zero, the target clamping stroke is less than the initial clamping stroke. If the difference is equal to zero, the target clamping stroke is equal to the initial clamping stroke.

[0121] In a possible implementation manner, the determining unit is further configured to:

[0122] If, within a continuous preset time period, the fluctuation value of the target clamping force is less than or equal to a first threshold, the fluctuation value of the target clamping stroke is less than or equal to a second threshold, and the deceleration fluctuation value of the vehicle is less than or equal to a third threshold, it is determined that the target clamping force and the target clamping stroke meet the stability condition.

[0123] In a possible implementation manner, the determining unit is further configured to:

[0124] The brake clamping stroke is sent to a brake controller corresponding to the brake of the vehicle, and the brake controller is used to control the brake according to the brake clamping stroke to achieve braking of the vehicle.

[0125] It can be seen from the above technical solution that in response to the first clamping force request for the vehicle, the initial clamping stroke corresponding to the target clamping force in the first clamping force request can be determined according to the initial curve between the clamping force and the clamping stroke. Then, the initial clamping stroke can be compensated according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the actual value of the vehicle deceleration, and the target clamping stroke corresponding to the target clamping force can be obtained, and the target clamping stroke can be used to control the vehicle for braking. Among them, the difference can be used to reflect the difference between the actual deceleration situation and the theoretical deceleration situation. Based on this, the compensation is performed, and the target clamping stroke obtained can more accurately control the vehicle for braking compared with the initial clamping stroke, so that the actual deceleration situation is close to the theoretical deceleration situation. If it is determined that the target clamping force and the target clamping stroke meet the stability condition, it means that the two are stable. At this time, the state of the vehicle's braking system is basically stable, so the target clamping force and the target clamping stroke can be constructed as a calibration data pair. Next, a target curve between the clamping force and the clamping stroke of the vehicle can be obtained by curve fitting based on multiple calibration data pairs. The target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke than the initial curve. Obtaining the target curve means completing the calibration of the vehicle's braking curve, and then the target curve can be used to guide the vehicle's braking process. Specifically, when a second clamping force request for the vehicle is received, the brake clamping stroke corresponding to the brake clamping force in the second clamping force request can be determined based on the target curve, and the brake clamping stroke can be used to control the vehicle to brake. Since the target curve can more accurately reflect the corresponding relationship between the clamping force and the clamping stroke, the brake clamping stroke determined based on the target curve can more accurately control the vehicle's braking.

[0126] A person of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above method embodiment; and the aforementioned storage medium can be at least one of the following media: read-only memory (English: Read-only Memory, abbreviated: ROM), RAM, magnetic disk or optical disk, etc. Various media that can store program codes.

[0127] For the device embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment. The device embodiment described above is only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0128] It should be noted that, in this article, relational terms such as "first" and "second", etc. (if any) are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0129] The above is a detailed introduction to a vehicle brake curve calibration method and device provided by the embodiment of the present application. The principle and implementation method of the present application are described in detail using specific examples. The description of the above embodiment is only used to help understand the method of the present application. At the same time, for those skilled in the art, according to the method of the present application, there will be changes in the specific implementation method and application scope.

[0130] In summary, the content of this specification should not be understood as limiting the present application, and any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in this application should be included in the protection scope of this application. Moreover, based on the implementations provided in the above aspects, this application can also be further combined to provide more implementations.

Claims

1. A method for calibrating a braking curve of a vehicle, It is characterized in that The method comprises: In response to a first clamping force request for the vehicle, determining an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between clamping force and clamping stroke; According to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, the initial clamping stroke is compensated to obtain a target clamping stroke corresponding to the target clamping force; the target clamping stroke is used to control the vehicle to brake; If it is determined that the target clamping force and the target clamping stroke meet a stability condition, constructing the target clamping force and the target clamping stroke into a calibration data pair; Performing curve fitting according to a plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle; When a second clamping force request for the vehicle is received, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request is determined according to the target curve, and the brake clamping stroke is used to control the vehicle to brake.

2. The method according to claim 1, It is characterized in that The method of performing curve fitting according to the plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle includes: Dividing the plurality of calibration data pairs into a plurality of calibration data groups according to the magnitudes of a plurality of target clamping forces included in the plurality of calibration data pairs; According to the calibration data pairs included in a calibration data group, curve fitting is performed to obtain a calibration curve; for the connection points of two adjacent calibration curves, the connection points correspond to the same clamping force and clamping stroke on the two calibration curves; The target curve is determined according to the calibration curves respectively corresponding to the multiple calibration data groups.

3. The method according to claim 2, It is characterized in that The method of dividing the plurality of calibration data pairs into a plurality of calibration data groups according to the magnitudes of the plurality of target clamping forces included in the plurality of calibration data pairs comprises: Obtaining and determining the clamping force segmentation points according to the initial curve; two adjacent clamping force segmentation points are used to identify a section of the curve on the initial curve; For the clamping force segmentation interval marked by two adjacent clamping force segmentation points, a calibration data pair in which the target clamping force satisfies the clamping force in the clamping force segmentation interval is used to form a calibration data group.

4. The method according to claim 3, It is characterized in that The connection point and the clamping force segmentation point correspond to the same clamping force.

5. The method according to claim 1, It is characterized in that The compensating the initial clamping stroke according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value to obtain the target clamping stroke corresponding to the target clamping force includes: determining a compensation stroke based on a difference between the vehicle deceleration request value and the vehicle deceleration actual value; The target clamping stroke is determined based on the initial clamping stroke and the compensation stroke.

6. The method according to claim 5, It is characterized in that The determining of the compensation stroke based on the difference between the vehicle deceleration request value and the vehicle deceleration actual value comprises: The difference is subjected to proportional-integral control using a proportional-integral control algorithm to determine the compensation stroke.

7. The method according to claim 5, It is characterized in that The difference is the difference between the vehicle deceleration request value and the vehicle deceleration actual value. If the difference is greater than zero, the target clamping stroke is greater than the initial clamping stroke. If the difference is less than zero, the target clamping stroke is less than the initial clamping stroke. If the difference is equal to zero, the target clamping stroke is equal to the initial clamping stroke.

8. The method according to claim 1, It is characterized in that The determining that the target clamping force and the target clamping stroke meet a stability condition includes: If, within a continuous preset time period, the fluctuation value of the target clamping force is less than or equal to a first threshold, the fluctuation value of the target clamping stroke is less than or equal to a second threshold, and the deceleration fluctuation value of the vehicle is less than or equal to a third threshold, it is determined that the target clamping force and the target clamping stroke meet the stability condition.

9. The method according to any one of claims 1 to 8, It is characterized in that The method further comprises: The brake clamping stroke is sent to a brake controller corresponding to the brake of the vehicle, and the brake controller is used to control the brake according to the brake clamping stroke to achieve braking of the vehicle.

10. A braking curve calibration device for a vehicle, It is characterized in that The device comprises a determination unit, a compensation unit, a construction unit and a fitting unit: The determining unit is configured to determine, in response to a first clamping force request for the vehicle, an initial clamping stroke corresponding to a target clamping force in the first clamping force request according to an initial curve between the clamping force and the clamping stroke; The compensation unit is used to compensate the initial clamping stroke according to the difference between the vehicle deceleration request value corresponding to the first clamping force request and the vehicle deceleration actual value, so as to obtain a target clamping stroke corresponding to the target clamping force; The target clamping stroke is used to control the vehicle to brake; The construction unit is used to construct the target clamping force and the target clamping stroke into a calibration data pair if it is determined that the target clamping force and the target clamping stroke meet a stability condition; The fitting unit is used to perform curve fitting according to a plurality of calibration data pairs to obtain a target curve between the clamping force and the clamping stroke of the vehicle; The determination unit is further configured to determine, when receiving a second clamping force request for the vehicle, a brake clamping stroke corresponding to the brake clamping force in the second clamping force request according to the target curve, wherein the brake clamping stroke is used to control the vehicle to brake.

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