Four-wheel synchronization method and system based on EMB

Abstract

The invention relates to an EMB-based four-wheel synchronization method and system, and relates to the technical field of vehicle braking. The method is applied to EMBs, and comprises the following steps: obtaining response duration of each EMB for a target clamping force request sent by a main controller; for each EMB, if the response duration of the EMB is greater than a preset response duration threshold value, judging that the EMB is a response lagging EMB; determining the EMB with the shortest response duration as a standard response EMB; respectively obtaining a first clamping force of a standard response EMB, a current motor rotating speed and a second clamping force of a response lag EMB; determining the clamping force adjustment amount of the response lag EMB; according to the first clamping force of the standard response EMB, the current motor rotating speed, the second clamping force of the response lagging EMB and a preset rotating speed proportion adjusting coefficient, the target motor rotating speed of the response lagging EMB is determined; and the response lag EMB operates according to the clamping force adjusting amount and the target motor rotating speed. According to the invention, the consistency of four-wheel braking response can be improved.

Description

Technical Field

[0001] The present application relates to the field of vehicle braking technology, and in particular to a four-wheel synchronization method and system based on EMB. Background Art

[0002] At present, in the automotive braking system, electromechanical brakes (EMB) are widely used in various vehicles due to their advantages such as fast response speed, high control accuracy, and high energy utilization efficiency. However, in actual applications, when the EMB system responds to the braking request issued by the domain controller (i.e., the upper controller), the response of the four-wheel EMB is often difficult to be completely synchronized, resulting in the possibility of lateral swing of the vehicle during braking, especially in emergency braking or high-speed driving, the driving safety of the vehicle is threatened.

[0003] Therefore, how to achieve synchronous response of four-wheel EMB and improve the braking stability and safety of the vehicle has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] Based on this, it is necessary to provide a four-wheel synchronization method and system based on EMB to address the above technical problems.

[0005] In a first aspect, a four-wheel synchronization method based on EMB is provided, the method being applied to EMB, the method comprising:

[0006] Obtaining the response time of each EMB to the target clamping force request sent by the main controller;

[0007] For each of the EMBs, if the response time of the EMB is greater than a preset response time threshold, the EMB is determined to be a delayed response EMB;

[0008] Determine the EMB with the shortest response time as the standard response EMB;

[0009] Respectively obtaining a first clamping force of the standard response EMB, a current motor speed, and a second clamping force of the delayed response EMB;

[0010] Determining a clamping force adjustment amount of the response lag EMB according to a first clamping force of the standard response EMB and a second clamping force of the response lag EMB;

[0011] Determine the target motor speed of the response lag EMB according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and a preset speed ratio adjustment coefficient;

[0012] The response lag EMB operates according to the clamping force adjustment amount and the target motor speed.

[0013] As an optional implementation manner, obtaining the response time of each EMB to the target clamping force request sent by the main controller includes:

[0014] Acquire a first moment when the main controller sends a target clamping force request and a second moment when each of the EMBs reaches the target clamping force;

[0015] For each of the EMBs, the difference between the second moment and the second moment when the EMB reaches the target clamping force is determined as the response duration of the EMB to the target clamping force request sent by the main controller.

[0016] As an optional implementation, the preset response time threshold is 50ms.

[0017] As an optional implementation, the method further includes:

[0018] For each of the EMBs, if the response duration of the EMB is less than or equal to the response duration threshold, the EMB is determined to be a normal response EMB.

[0019] As an optional implementation, the formula for determining the clamping force adjustment amount of the response lag EMB according to the first clamping force of the standard response EMB and the second clamping force of the response lag EMB is:

[0020] ΔF = F1 - F2;

[0021] Wherein, ΔF is the clamping force adjustment amount of the response hysteresis EMB, F1 is the first clamping force of the standard response EMB, and F2 is the second clamping force of the response hysteresis EMB.

[0022] As an optional implementation, the formula for determining the target motor speed of the response lag EMB according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and a preset speed ratio adjustment coefficient is:

[0023] V1=V0+K(F1-F2);

[0024] Among them, V1 is the target motor speed, V0 is the current motor speed of the standard response EMB, F1 is the first clamping force of the standard response EMB, F2 is the second clamping force of the response lag EMB, and K is the preset speed ratio adjustment coefficient.

[0025] As an optional implementation, the method further includes:

[0026] Obtaining the clamping force change rate of the response hysteresis EMB;

[0027] When the clamping force change rate is greater than a preset rate change safety threshold, the motor speed of the response lag EMB is dynamically reduced.

[0028] As an optional implementation, the method further includes:

[0029] The EMB control of the front and rear wheels is independent of each other.

[0030] In a second aspect, a four-wheel synchronization system based on an EMB is provided, the system comprising a main controller and the EMB as described in any one of the first aspect.

[0031] The present application provides a four-wheel synchronization method and system based on EMB. The technical solution provided by the embodiments of the present application brings at least the following beneficial effects. The method is applied to EMB, and the method includes: obtaining the response time of each EMB to the target clamping force request sent by the main controller; for each EMB, if the response time of the EMB is greater than a preset response time threshold, the EMB is determined to be a response-delayed EMB; the EMB with the shortest response time is determined as the standard response EMB; the first clamping force of the standard response EMB, the current motor speed and the second clamping force of the response-delayed EMB are respectively obtained; according to the first clamping force of the standard response EMB and the second clamping force of the response-delayed EMB, the clamping force adjustment amount of the response-delayed EMB is determined; according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response-delayed EMB and a preset speed ratio adjustment coefficient, the target motor speed of the response-delayed EMB is determined; the response-delayed EMB operates according to the clamping force adjustment amount and the target motor speed. The present application obtains the response time of each EMB, determines the response lag EMB, and uses the standard response EMB as a benchmark to adjust the motor speed and clamping force output of the lag EMB, which can significantly improve the consistency of the four-wheel response and effectively solve the problems of poor braking stability and loss of control under extreme conditions caused by asynchronous response in the prior art.

[0032] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 A schematic diagram of the structure of a four-wheel synchronization system based on EMB provided in an embodiment of the present application;

[0035] Figure 2 A flowchart of a four-wheel synchronization method based on EMB provided in an embodiment of the present application;

[0036] Figure 3 A flowchart of a method for calculating the EMB response duration provided in an embodiment of the present application;

[0037] Figure 4 A flowchart of a method for monitoring an EMB adjustment process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0039] The four-wheel synchronization method based on EMB provided in the embodiment of the present application can be applied to a four-wheel synchronization system based on EMB. Figure 1 As shown, the system includes a main controller 110 and several EMBs 120. The main controller 110 is connected to all EMBs 120 via a vehicle communication bus (such as a CAN bus, a FlexRay bus or an Ethernet) to send control instructions and receive operating status data. Each EMB 120 is independently connected to the communication bus, and shares data and receives instructions through the bus, forming a distributed braking control architecture. The main controller 110 can also calculate the target clamping force request of each wheel according to the driver's braking demand or the intervention signal of the vehicle stability control system, and send it to the corresponding EMB 120. Several EMBs 120 integrate synchronization monitoring programs, and each EMB 120 can collect its own operating status parameters in real time, including actual clamping force, relative position, motor speed, current, response time, etc. The collected parameters are uploaded to the main controller 110 via the communication bus and broadcast to other EMBs 120 at the same time. The status data of other EMBs are read through the communication bus, and the clamping force difference and motor speed difference between itself and the standard response EMB are calculated. According to the adjustment instructions sent by the main controller 110, adjust its own motor speed and clamping force output to catch up with the standard response EMB. According to the target clamping force request sent by the main controller 110, drive the motor to generate the corresponding braking torque, and adjust in real time to achieve rapid response. Monitor the change rate of its own motor current and clamping force. If it exceeds the safety threshold, trigger the protection mechanism, dynamically reduce the motor speed and report the abnormal state.

[0040] The following will describe in detail a four-wheel synchronization method based on EMB provided in an embodiment of the present application in conjunction with a specific implementation method. Figure 2 A flowchart of a four-wheel synchronization method based on EMB is provided in an embodiment of the present application, such as Figure 2 As shown, the method is applied to EMB, and the specific steps are as follows:

[0041] Step 201 : Obtain the response time of each EMB to the target clamping force request sent by the main controller.

[0042] In practice, the response time is the time interval after the main controller sends a target clamping force request and each EMB reaches the target clamping force. By comparing the response time, it is possible to determine which EMBs respond normally or lag. For example, the main controller sends a target clamping force request and records the timestamp of the request. Each EMB adjusts the clamping force according to the request and records the timestamp when the clamping force reaches the target value. Then, the response time is determined based on the time interval between the timestamps.

[0043] As an optional implementation, Figure 3 A flowchart of a method for calculating the EMB response time provided in an embodiment of the present application is shown in FIG. Figure 3 As shown, the specific steps of obtaining the response time of each EMB to the target clamping force request sent by the main controller in step 201 are as follows:

[0044] Step 301 , obtaining the first moment when the main controller sends a target clamping force request and the second moment when each EMB reaches the target clamping force.

[0045] In practice, the main controller sends a target clamping force request instruction to each EMB and records the time of sending the instruction as the first moment (T1). After receiving the instruction, each EMB starts to perform the clamping action and monitors its own clamping force output in real time. When the actual clamping force of an EMB reaches the target clamping force requested by the main controller, the moment is recorded as the second moment (T2).

[0046] Step 302 : for each EMB, determine the difference between the second moment and the second moment when the EMB reaches the target clamping force as the response time of the EMB to the target clamping force request sent by the main controller.

[0047] In implementation, each EMB can determine the time taken by each EMB from receiving the target clamping force request from the main controller to actually reaching the clamping force. The response time reflects the efficiency of the EMB in executing the main controller's instructions.

[0048] Step 202: for each EMB, if the response time of the EMB is greater than a preset response time threshold, the EMB is determined to be a delayed response EMB.

[0049] In implementation, the response time of each EMB is compared with a preset response time threshold (e.g., 50ms) to determine the response-delayed EMB so that synchronous compensation measures can be taken in subsequent steps. For example, if the preset response time threshold is 50ms, the response time of EMB1 is 40ms, and the response time of EMB2 is 60ms, EMB2 determines itself as the response-delayed EMB.

[0050] As an optional implementation, the preset response time threshold is 50ms.

[0051] As an optional implementation manner, for each EMB, if the response duration of the EMB is less than or equal to the response duration threshold, the EMB is determined to be a normal response EMB.

[0052] Step 203: determine the EMB with the shortest response time as the standard response EMB.

[0053] In implementation, the EMB with the shortest response time is selected as the benchmark, and its state parameters are used to calculate the compensation parameters of other EMBs with delayed response. For example, the response times of four EMBs are EMB140ms, EMB260ms, EMB345ms, and EMB450ms, respectively. The one with the shortest response time is EMB1, and the other EMBs determine EMB1 as the standard response EMB.

[0054] Step 204 , respectively obtain the first clamping force of the standard response EMB, the current motor speed, and the second clamping force of the delayed response EMB.

[0055] In implementation, each EMB can obtain the actual clamping force (first clamping force) and current motor speed of the standard response EMB through the communication bus, and the lagging EMB can obtain its own actual clamping force (second clamping force) to provide basic data for subsequent synchronization adjustment. For example: the first clamping force of the standard response EMB (EMB1) is 950N, and the current motor speed is 1500rpm. The second clamping force of the response lagging EMB (EMB2) is 900N.

[0056] Step 205 , determining a clamping force adjustment amount of the response hysteresis EMB according to the first clamping force of the standard response EMB and the second clamping force of the response hysteresis EMB.

[0057] In implementation, the response hysteresis EMB can calculate a clamping force adjustment amount for quickly approaching the clamping force of the standard response EMB.

[0058] As an optional implementation, in step 205, the formula for determining the clamping force adjustment amount of the response hysteresis EMB is as follows according to the first clamping force of the standard response EMB and the second clamping force of the response hysteresis EMB:

[0059] ΔF = F1 - F2;

[0060] Wherein, ΔF is the clamping force adjustment amount of the response hysteresis EMB, F1 is the first clamping force of the standard response EMB, and F2 is the second clamping force of the response hysteresis EMB.

[0061] In implementation, the first clamping force (F1) of the standard response EMB is the clamping force applied by the EMB with the fastest response under the current conditions, and this value can be used as the target clamping force benchmark for the entire system. The second clamping force (F2) of the response lag EMB is the clamping force value actually applied by the response lag EMB. By calculating ΔF=F1-F2, the clamping force difference between the response lag EMB and the standard response EMB can be obtained, that is, the clamping force that the response lag EMB needs to increase or decrease to achieve the synchronization target. For example: the clamping force of the standard response EMB is F1=950N, and the clamping force of the response lag EMB is F2=920N; according to the formula: ΔF=F1-F2=950N-920N=30N. The response lag EMB needs to adjust its motor output or control parameters to increase its clamping force by 30N, so that its clamping force is synchronized with the standard response EMB.

[0062] Step 206 , determining a target motor speed of the response lag EMB according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and a preset speed ratio adjustment coefficient.

[0063] In implementation, the response lag EMB can calculate the target motor speed through the current motor speed and clamping force difference of the standard response EMB, ensuring that the adjustment speed of the lag EMB meets the synchronization requirement.

[0064] As an optional implementation, in step 206, according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and the preset speed ratio adjustment coefficient, the formula for determining the target motor speed of the response lag EMB is:

[0065] V1=V0+K(F1-F2);

[0066] Among them, V1 is the target motor speed, V0 is the current motor speed of the standard response EMB, F1 is the first clamping force of the standard response EMB, F2 is the second clamping force of the response lag EMB, and K is the preset speed ratio adjustment coefficient.

[0067] In practice, V1 is the target motor speed of the response lag EMB, representing the adjusted motor running speed to achieve the purpose of synchronous clamping force. V0 is the current motor speed of the standard response EMB, which is used as a reference value to reflect the motor running state of the fastest response EMB. F1 and F2 are the first clamping force of the standard response EMB and the second clamping force of the response lag EMB, respectively, reflecting the difference in clamping force between the two. K is the preset speed proportional adjustment coefficient, which is used to balance the relationship between the clamping force and the motor speed to avoid excessive or insufficient adjustment. When the clamping force (F2) of the response lag EMB is less than the clamping force (F1) of the standard response EMB, the motor speed needs to be increased, and the target speed V1>V0. The larger the clamping force difference (F1-F2), the higher the adjustment range of the motor speed, ensuring the rapid response of the synchronous action. The speed proportional adjustment coefficient K can control the sensitivity of the speed adjustment, which needs to be preset according to the specific braking requirements of the vehicle to ensure that the clamping force after adjustment gradually approaches the target value without causing overshoot or oscillation. For example: the current motor speed V0 of the standard response EMB is 1500rpm, the clamping force F1 of the standard response EMB is 950N, the clamping force F2 of the delayed response EMB is 900N, and the speed proportional adjustment coefficient K is 5rpm / N. According to the formula, the target motor speed of the delayed response EMB is calculated to be 1750rpm, which is 250rpm higher than the current motor speed of the standard response EMB, in order to reduce the clamping force difference (ΔF).

[0068] Step 207 , the response hysteresis EMB operates according to the clamping force adjustment amount and the target motor speed.

[0069] In implementation, the response lag EMB performs synchronous adjustment so that its clamping force and click speed gradually approach the standard response EMB, and finally achieves four-wheel synchronous response. For example: the response lag EMB (EMB2) adjusts the motor speed to 2000rpm and increases the clamping force by 40N to reach the target clamping force of 950N required by the main controller.

[0070] As an optional implementation, Figure 4 A flow chart of a method for monitoring an EMB adjustment process provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the specific steps are as follows:

[0071] Step 401, obtaining the clamping force change rate of the response-delayed EMB.

[0072] In practice, the clamping force change rate refers to the change in the clamping force per unit time. If the clamping force change rate is too fast, there is a risk of overshoot, which will cause vibration or instability in the brake system and even affect the braking effect of the entire vehicle. By real-time monitoring of the clamping force change rate, the motor speed of the EMB with a response lag can be intervened in time to avoid safety hazards.

[0073] Step 402 : When the clamping force change rate is greater than a preset rate change safety threshold, dynamically reduce the motor speed of the response lag EMB.

[0074] In practice, technicians can preset a safety threshold for the clamping force change rate. If the response hysteresis EMB detects that the clamping force change rate is greater than the preset safety threshold, it means that the clamping force is adjusted too fast, and the adjustment process can be slowed down by reducing the motor speed. For example, a dynamic adjustment coefficient that is negatively correlated with the clamping force change rate is set.

[0075] As an optional implementation, the EMB controls of the front wheel group and the rear wheel group are independent of each other.

[0076] In practice, the EMB control of the front wheel group and the rear wheel group is independent of each other to ensure the synchronization of the EMB response within the front wheel group and the rear wheel group. Specifically, the cross-coupling control method can be used. In the synchronous control of the four-wheel EMB, the cross-coupling control is mainly applied between the front wheel group and the rear wheel group. The two EMBs in each wheel group share parameters such as clamping force and motor speed, calculate each other's errors (such as clamping force difference, motor speed difference), and adjust their own control output according to the error to achieve synchronization. Independent control between the front wheel group and the rear wheel group can avoid the difference in adhesion conditions between the front and rear wheels affecting each other's dynamic stability.

[0077] The embodiment of the present application provides a four-wheel synchronization method based on EMB. The method is applied to EMB, and the method includes: obtaining the response time of each EMB to the target clamping force request sent by the main controller; for each EMB, if the response time of the EMB is greater than the preset response time threshold, the EMB is determined to be a response-delayed EMB; the EMB with the shortest response time is determined as the standard response EMB; the first clamping force of the standard response EMB, the current motor speed and the second clamping force of the response-delayed EMB are respectively obtained; according to the first clamping force of the standard response EMB and the second clamping force of the response-delayed EMB, the clamping force adjustment amount of the response-delayed EMB is determined; according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response-delayed EMB and the preset speed ratio adjustment coefficient, the target motor speed of the response-delayed EMB is determined; the response-delayed EMB operates according to the clamping force adjustment amount and the target motor speed. The embodiment of the present application obtains the response time of each EMB, determines the response hysteresis EMB, and uses the standard response EMB as a reference to adjust the motor speed and clamping force output of the hysteresis EMB, which can significantly improve the consistency of the four-wheel response and effectively solve the problems of poor braking stability and loss of control under extreme conditions caused by asynchronous response in the prior art. By independently controlling the front and rear wheel groups, the left and right swaying phenomenon of the vehicle body caused by uneven clamping force can be effectively reduced. Under low-adhesion road or open road conditions, rapid compensation for the hysteresis EMB can be achieved to ensure vehicle braking stability and avoid the risk of loss of control. Dynamically adjust the motor speed and clamping force output of the hysteresis EMB, which can quickly respond to the target clamping force request of the main controller and adapt to different vehicle operating states and braking conditions. Adjust the speed ratio adjustment coefficient according to the vehicle speed, yaw rate and acceleration to improve the robustness and control accuracy of the system under complex conditions. Real-time monitoring of the motor current and clamping force change rate, when exceeding the safety threshold, dynamically adjust the motor speed and generate a warning signal to avoid motor damage caused by overload. By precisely adjusting the response lag EMB, unnecessary energy consumption caused by asynchrony is reduced, the overall energy utilization efficiency of the system is optimized, and the service life of the equipment is extended.

[0078] It should be understood that although Figures 2 to 4 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figures 2 to 4At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0079] It can be understood that the same / similar parts between the various embodiments of the above method in this specification can refer to each other, and each embodiment focuses on the differences from other embodiments. For related points, please refer to the description of other method embodiments.

[0080] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0081] It should be noted that, in this article, relational terms such as first and second, etc. are only used 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 existence of other identical elements in the process, method, article or device including the elements.

[0082] It should also be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for display, data for analysis, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties.

[0083] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0084] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0085] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A four-wheel synchronization method based on EMB, characterized in that: The method is applied to EMB, and the method comprises: Obtaining the response time of each EMB to the target clamping force request sent by the main controller; For each of the EMBs, if the response time of the EMB is greater than a preset response time threshold, the EMB is determined to be a delayed response EMB; Determine the EMB with the shortest response time as the standard response EMB; Respectively obtaining a first clamping force of the standard response EMB, a current motor speed, and a second clamping force of the delayed response EMB; Determining a clamping force adjustment amount of the response lag EMB according to a first clamping force of the standard response EMB and a second clamping force of the response lag EMB; Determine the target motor speed of the response lag EMB according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and a preset speed ratio adjustment coefficient; The response lag EMB operates according to the clamping force adjustment amount and the target motor speed.

2. The method according to claim 1, characterized in that The step of obtaining the response time of each EMB to the target clamping force request sent by the main controller includes: Acquire a first moment when the main controller sends a target clamping force request and a second moment when each of the EMBs reaches the target clamping force; For each of the EMBs, the difference between the second moment and the second moment when the EMB reaches the target clamping force is determined as the response duration of the EMB to the target clamping force request sent by the main controller.

3. The method according to claim 1, characterized in that The preset response time threshold is 50ms.

4. The method according to claim 1, characterized in that: The method further comprises: For each of the EMBs, if the response duration of the EMB is less than or equal to the response duration threshold, the EMB is determined to be a normal response EMB.

5. The method according to claim 1, characterized in that: The formula for determining the clamping force adjustment amount of the response lag EMB according to the first clamping force of the standard response EMB and the second clamping force of the response lag EMB is: ΔF = F1 - F2; Wherein, ΔF is the clamping force adjustment amount of the response hysteresis EMB, F1 is the first clamping force of the standard response EMB, and F2 is the second clamping force of the response hysteresis EMB.

6. The method according to claim 1, characterized in that The formula for determining the target motor speed of the response lag EMB according to the first clamping force of the standard response EMB, the current motor speed, the second clamping force of the response lag EMB and the preset speed ratio adjustment coefficient is: V1=V0+K(F1-F2); Among them, V1 is the target motor speed, V0 is the current motor speed of the standard response EMB, F1 is the first clamping force of the standard response EMB, F2 is the second clamping force of the response lag EMB, and K is the preset speed ratio adjustment coefficient.

7. The method according to claim 1, characterized in that The method further comprises: Obtaining the clamping force change rate of the response hysteresis EMB; When the clamping force change rate is greater than a preset rate change safety threshold, the motor speed of the response lag EMB is dynamically reduced.

8. The method according to claim 1, characterized in that: The method further comprises: The EMB control of the front and rear wheels is independent of each other.

9. A four-wheel synchronization system based on EMB, characterized in that: The system comprises a main controller and an EMB as claimed in any one of claims 1-8.

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