Brake anti-lock control method, reference vehicle speed calculation method, and torque difference correction calculation method

Abstract

The application provides a brake anti-lock control method, a reference vehicle speed calculation method and a torque difference correction calculation method, comprising a plurality of brake modules with an axle as a basic unit, power supply of each brake module is connected to a same battery, air supply of each brake module is connected to a same gas storage tank, and communication of each brake module is connected to a same main control ECU; the brake module comprises a brake pressure module, a brake wheel cylinder and a wheel speed sensor, the brake pressure module comprises a first brake output port and a second brake output port, at least one brake wheel cylinder is connected to the first brake output port and the second brake output port respectively, and the brake pressure module controls actual pressure of the brake wheel cylinder according to brake pressure of a vehicle wheel received on a vehicle network; the technical scheme can realize reduction of main control calculation and support of a chassis with more axle numbers.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field, in particular to a brake anti-lock control method, a reference vehicle speed calculation method and a torque difference correction calculation method. BACKGROUND

[0002] The multi-axle commercial vehicles on the market are mainly 6-axle (3-axle main vehicle + 3-axle trailer), and the number of vehicles with more than 6-axle (referred to as multi-axle vehicle) is very low. There are few brake systems (which require anti-lock function) for vehicles with more than 6-axle on the market, which has a great impact on the chassis design and safety of multi-axle vehicles. In addition, due to the large number of axles of multi-axle vehicles, the configuration of multi-axle chassis brake system is inevitably complex. It is a great workload to develop brake system hardware and responsive anti-lock control software for multi-axle vehicles with different numbers of axles. If a brake system and software are developed for vehicles with different numbers of axles, the workload will inevitably increase. Patent CN114954390B invents a distributed system for 6-axle vehicles. This system reduces the complexity of the system to some extent due to its distributed and modular characteristics. However, the software (calculation of reference vehicle speed) and circuit (such as central control unit) are designed for 6-axle vehicles and cannot be extended to multi-axle vehicles with more axles. In patent CN118560443B, a brake system configuration for 6-axle vehicles is proposed. The first main control unit is responsible for controlling the 1st, 3rd and 5th axles, and the second main control unit is responsible for controlling the 2nd, 4th and 6th axles. This method can control the 6-axle chassis. If a third main control unit is added, the control of 9-axle vehicles can be realized. This method can easily expand the number of axles. However, each main control unit is an independent unit and does not communicate with other systems, i.e. the three axles connected to it are considered as one vehicle in software control. However, these three axles are not actually one vehicle. This independent control ignores the interaction between other axles and these axles, affecting the braking intensity of the whole vehicle and the braking deviation (yaw) on uneven road surface. To solve the above problems, the present application is proposed. SUMMARY

[0003] Therefore, the present application aims to provide a brake anti-lock control method, a reference vehicle speed calculation method and a torque difference correction calculation method, which can reduce the calculation of the main control unit and support more axles of the chassis.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical solution: a brake anti-lock control method, comprising the following steps:

[0005] Step A1, calculating the locking tendency of a single wheel: first, calculating the slip rate of the wheel;

[0006] Step A2, calculating the differential value of the wheel speed, i.e. the instantaneous acceleration; then calculating the filtered wheel acceleration according to the mean value filtering;

[0007] Step A3, calculating the vehicle acceleration according to the wheel acceleration calculation mode;

[0008] Step A4, calculating the locking degree fuzzy logic;

[0009] Step A5, jumping the pressure control of the single wheel according to the fuzzy logic;

[0010] Step A6, correcting the pressure control logic according to the torque difference limitation of the left and right wheels;

[0011] The step A4 specifically comprises:

[0012] Firstly, the fuzzy logic 1, is an index of locking degree aggravation, the slip rate of the wheel is larger when the locking degree aggravates, or the deceleration of the wheel is larger than the deceleration of the vehicle, or the deceleration of the wheel has exceeded the deceleration of the vehicle;

[0013] The expression of setting the fuzzy large is ,

[0014] The expression of setting the fuzzy small is ,

[0015] The fuzzy or logic is ; wherein, γ represents a variable, and max(*) represents the maximum value of the variable x and the variable y;

[0016] The fuzzy and logic is ; wherein, min(*) represents the minimum value of the variable x and the variable y;

[0017] Then, the condition 1 is calculated as ,

[0018] The condition 2 is calculated as , wherein, a i represents the acceleration of the i-th wheel, represents the vehicle acceleration;

[0019] The condition 3 is calculated as ,

[0020] Then is represented as ;

[0021] The fuzzy logic 2, is an index of too small brake pressure, when the brake pressure is too small, the speed of the wheel is close to the vehicle speed, i.e. the slip rate is smaller, or the deceleration of the wheel is close to the deceleration of the vehicle;

[0022] Then, the condition 1 is calculated as ,

[0023] Condition 2 is calculated as ,

[0024] Then ;

[0025] The step A5 specifically includes: when is satisfied, it indicates that the brake pressure is very small, and the pressure needs to be increased quickly; when is satisfied, it indicates that the brake pressure is small, and the pressure is increased slowly; when is satisfied, it indicates that the lockup degree is very large, and the pressure needs to be decreased quickly; when is satisfied, it indicates that the lockup degree is small, and the pressure is decreased slowly; when is satisfied, it indicates that the brake pressure is appropriate at this time, and the pressure should be maintained; , , , and all represent threshold values, and satisfy , ;

[0026] The step A6 specifically includes: when the torque deviation upper limit given by the master control strategy is , the brake pressures of the left and right wheels of the single axle and should satisfy , wherein is the distance between the left and right wheels of the axle, is the brake disc coefficient, indicating the ratio of the brake torque and the brake pressure, is the rolling radius of the wheel, if , the brake pressure of the left wheel is required to be not more than a certain value, i.e. , if , the brake pressure of the right wheel is limited to be not more than a certain value, i.e. .

[0027] In a preferred embodiment, the brake system is applied to a modularly expandable brake system, which includes a modularly expandable brake unit. The modularly expandable brake unit includes a plurality of brake modules which are basic units of an axle. The power supply of each brake module is connected to the same battery, the gas supply of each brake module is connected to the same gas tank, and the communication of each brake module is connected to the same master ECU. The master ECUs of each modularly expandable brake unit form a star communication network, and the star communication networks communicate with each other.

[0028] The brake module comprises a brake pressure module, brake wheel cylinders and wheel speed sensors, the brake pressure module comprises a first brake output port and a second brake output port; the first brake output port and the second brake output port are respectively connected with at least one brake wheel cylinder; the brake pressure module controls the actual pressure of the brake wheel cylinder according to the brake pressure of the wheels received on the vehicle network.

[0029] In a preferred embodiment, when the first brake output port and the second brake output port are respectively connected with two brake wheel cylinders, the brake wheel cylinders connected with the same brake output port are two wheels on the same side.

[0030] The application also provides a reference vehicle speed calculation method, which is applied to the modularly expandable brake system of the brake anti-lock control method, and provides a speed reference for judging the wheel state, and comprises the following steps:

[0031] Step B1: constructing a 6-wheel vehicle reference vehicle speed calculation method and converting it into a 4-wheel calculation mode; the method for calculating the reference vehicle speed based on the four-wheel speed is denoted as For a 6-wheel vehicle, the reference vehicle speed calculation of the first and second axes is The reference vehicle speed calculation of the second and third axes is The reference vehicle speed calculation of the whole vehicle is A variable is added ; wherein v1, v2, v3, v4, v5 and v6 respectively represent the first axis left wheel, the first axis right wheel, the second axis left wheel, the second axis right wheel, the third axis left wheel and the third axis right wheel.

[0032] Step B2: splitting the multi-axis vehicle into a combination of 2-axis or 3-axis vehicle bodies, and then calculating the reference vehicle speed; the reference vehicle speed of the ith vehicle body is denoted as The vehicle reference vehicle speed is , wherein is the total number of wheels of the ith vehicle body.

[0033] The application also provides a moment difference correction calculation method, which is applied to the modularly expandable brake system of the brake anti-lock control method, and comprises the following steps:

[0034] For the whole vehicle yaw moment limit , it should be split into the yaw moment limit of each axis , wherein j represents the jth axis.

[0035] Step C1: decomposing the whole vehicle yaw moment to each axis according to n axes, .

[0036] Step C2: judging which axes reach the limit , the number of axes reaching the limit is calculated as m;

[0037] Step C3: for the axes not reaching the limit, record the current generated yaw moment difference as , the maximum change of the yaw moment at the next time is , the limit amount at the next time is ;

[0038] Step C4: for the axes reaching the limit, the limit amount is calculated as ;

[0039] Step C5: loop Step C2 to Step C5, update .

[0040] Compared with the prior art, the application has the following beneficial effects: reducing the calculation of the master control, and supporting more axes of the chassis. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a single-axis braking module schematic diagram of the preferred embodiment of the application;

[0042] Figure 2 is a double-axis braking module schematic diagram of the preferred embodiment of the application;

[0043] Figure 3 is a single master control ECU architecture schematic diagram of the preferred embodiment of the application;

[0044] Figure 4 is a multi-master control ECU architecture schematic diagram of the preferred embodiment of the application;

[0045] Figure 5 is a whole vehicle control architecture schematic diagram of the preferred embodiment of the application;

[0046] Figure 6 is a single-wheel ABS control logic schematic diagram of the preferred embodiment of the application;

[0047] Figure 7 is a four-axis vehicle ABS control effect schematic diagram of the preferred embodiment of the application, wherein (a) is the front four-wheel speed, (b) is the rear four-wheel speed, (c) is the front four-wheel brake pressure, and (d) is the rear four-wheel brake pressure. DETAILED DESCRIPTION

[0048] The application will be further described below in combination with the drawings and embodiments.

[0049] ​It should be noted that the following detailed description is illustrative only, and is intended to provide further description in order to provide a fuller enabling and understanding of the present application. Unless otherwise indicated herein, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application pertains.

[0050] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application; as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0051] I. Modularly expandable brake unit

[0052] In particular, with reference to Figure 1 , the modularly expandable brake unit comprises a plurality of brake modules as basic units of an axle, the power supply of each brake module is connected to the same battery, the gas supply of each brake module is connected to the same gas tank, and the communication of each brake module is connected to the same master ECU;

[0053] The brake module comprises a brake pressure module b1, a brake wheel cylinder a, and a wheel speed sensor. The brake pressure module comprises a first brake output port 21 and a second brake output port 22. The first brake output port 21 and the second brake output port 22 are respectively connected to at least one brake wheel cylinder a. The brake pressure module b1 comprises an ECU and a mechanical structure. The ECU controls the actual pressure of the wheel cylinder according to the brake pressure of each wheel received on the vehicle network. The wheel speed sensor c is used to measure the actual speed of the wheel. The connection of the brake module with the outside includes a communication network for communication with other controllers, gas supply, and power supply. The brake module is used to process the braking of a single axle. If two brake wheel cylinders are connected to the same first brake output port 21 and the second brake output port 22, as shown in Figure 2 , they can be used for dual axle braking. The wheel cylinders connected to the same output port must be on the same side (both left wheels or both right wheels). At the same time, the wheel speed sensor measures the speed of the corresponding wheels of the wheel cylinders. Since the pressures of the two wheels are the same, low selection control logic is used in control to prevent one wheel from being locked and the other from not being locked.

[0054] II. Modularly expandable brake system

[0055] In particular, in order to adapt to vehicles with different numbers of axles while minimizing the complexity of the system, as Figure 3The system shown can expand the system architecture, the main features are 1) each axis is the single-axis brake unit described above, which controls the pressure of the axis according to the wheel speed state of the axis, thereby realizing different ABS control functions, so that adding axes does not need to change the ABS control code; 2) the system is a star architecture, that is, the power supply, gas supply, and communication of each module are directly with the battery, gas tank, and main control ECU, so that it is very convenient to want to add an axis module to the system; 3) the main control ECU is responsible for calculating the common information of the whole vehicle (such as vehicle speed, brake deviation correction value), and distributing it to each axis module, so that the common information does not need to be calculated repeatedly at each axis, reducing the calculation amount. In this configuration, the axis module shown can also be used Figure 2 The axis module shown replaces the existing axis module to realize a chassis that supports more axes.

[0056] The single-ECU architecture described above has a significant problem that as the number of axes increases, the ECU's calculation amount will gradually increase. A feasible solution is to use a larger ECU when the calculation power is not enough, but this requires the development of a new ECU. To solve this problem, a multi-main control ECU architecture is proposed as shown Figure 4 The multi-main control ECU architecture is used to adapt to more axis vehicles. The main features are 1) the main control 1 and the corresponding axis module form a star communication network 1, the main control 2 forms a star communication network 2, and the main control 1 and 2 communicate with each other; 2) power supply and gas supply can be two independent star networks or one large star network; 3) the main control 1 is responsible for processing the common information of the axes connected to it, and the main control 2 is responsible for processing the common information of the axes connected to it, and the information between them is interacted. Compared with patent CN118560443B, this way can share information between the two systems, which can avoid the problem of affecting the braking intensity of the whole vehicle and the brake deviation (yaw) on the uneven road surface. At the same time, since the above problem can be avoided, it is not necessary to connect the 135 axes and the 246 axes alternately to the two main controls as mentioned in patent CN118560443B, but can connect the corresponding main controls according to the principle of proximity 123 axes and 456 axes, which makes the system installation more convenient, and the communication line is shorter and the cost is lower.

[0057] III. Modular brake anti-lock control method

[0058] As shown in Figure 5 The main features are that the axis 1 to axis n module is responsible for feeding back the current left and right wheel speed and the torque difference of the left and right wheels, the main control calculates the vehicle speed according to the feedback wheel speed, and calculates the upper limit value of the torque difference allowed by each axis. The axis 1 to axis n module performs ABS control according to the reference vehicle speed and the current wheel speed, and limits the brake force value of the wheel with larger brake pressure to exceed the brake force value of the wheel with smaller brake pressure + the brake force difference required by the torque difference limit when controlling.

[0059] The control strategy of ABS is that ABS intervenes when the wheel has a tendency to lock or has locked, at this time the pressure of the wheel is limited to the pressure expected by the driver, when ABS exits, the pressure of the wheel is not limited, at this time the pressure of the wheel automatically follows the pressure expected by the driver. The ABS strategy proposed by the method includes the following steps.

[0060] Step A1: Calculate the locking tendency of a single wheel: first calculate the slip ratio of the wheel , in which is the longitudinal speed of the vehicle, since the actual longitudinal speed of the vehicle is unknown, it is taken as the reference speed here, is the longitudinal speed of the i-th wheel (1 represents the left of the first axle, 2 represents the right of the first axle, 3 represents the left of the second axle, …), which is calculated by the rotation angular velocity of the wheel speed sensor and the wheel radius . .

[0061] Step A2: Calculate the differential value of the wheel speed (i.e. the instantaneous acceleration) , in which is the instantaneous acceleration at the current time (t time), and and are the wheel speeds at the current time and the previous time, is the time interval of each sampling (which can be set to 10 ms), and then the filtered wheel acceleration is calculated according to the mean filtering, which is to filter out the wheel speed fluctuations caused by vehicle vibration, and is calculated as , represents the instantaneous acceleration of the wheel at the j-th time before the current time, and n is the total number of mean filtering (which can be taken as 5).

[0062] Step A3: Calculate the vehicle acceleration according to the way of calculating the wheel acceleration , i.e. , , is the longitudinal speed of the vehicle, and are the vehicle speeds at the current time and the previous time, is the vehicle acceleration, represents the instantaneous acceleration of the vehicle at the j-th time before the current time, since the fluctuation of the vehicle deceleration is generally small, n should be taken as a larger number (such as 10).

[0063] Step A4: Calculate the locking degree fuzzy logic.

[0064] First fuzzy logic 1, is an index of the aggravation of the lock, under which condition mainly the slip ratio of the wheel is large, or the deceleration of the wheel (negative value of acceleration) is larger than the deceleration of the whole vehicle, or the deceleration of the wheel has exceeded the deceleration of the whole vehicle (usually the deceleration of the vehicle will not exceed 10 m / s2, i.e. the value of gravitational acceleration);

[0065] The expression of setting the large blur is ,

[0066] The expression of setting the small blur is ,

[0067] Fuzzy or logic ;

[0068] Fuzzy and logic ;

[0069] The condition 1 is calculated as ,

[0070] The condition 2 is calculated as ,

[0071] The condition 3 is calculated as ,

[0072] Then is expressed as .

[0073] Fuzzy logic 2, is an index of the too small brake pressure, when the brake pressure is too small, the speed of the wheel should be close to the speed of the whole vehicle, i.e. the slip ratio is small, or the deceleration of the wheel is close to the deceleration of the whole vehicle. Then the condition 1 is calculated as , the condition 2 is calculated as , and . It should be noted that the above preset constants 0.1, etc. are pre-given values, and the values of different vehicles may have slight differences.

[0074] Step A5: Jumping the pressure control of the single wheel according to the fuzzy logic.

[0075] Reference Figures 6-7 , when is satisfied (the typical value of may be 0.8), it means that the brake pressure is very small, and the pressure needs to be increased quickly; when is satisfied (the typical value of may be 0.5), it means that the brake pressure is small, and the pressure can be increased slowly (if the pressure is increased quickly at this time, it is easy to cause the pressure to be increased too much to cause lock); when , it means that the lock degree is very large (the typical value of may be 0.8), and the pressure needs to be reduced quickly; when , it means that the lock degree is small ( A typical value for this is 0.5), requiring slow decompression; when This indicates that there is almost no degree of hold-up ( A typical value for this is 0.3), at which point the braking pressure is appropriate and should be maintained. It is important to note that the above threshold must be met. , .

[0076] The above-mentioned rapid pressurization means that the software does not limit the pressurization speed (only limited by hardware), slow pressurization means switching between rapid pressurization and pressure holding at certain intervals, for example, 10ms rapid pressurization and 30ms pressure holding. Pressure holding means that the pressure does not increase or decrease. Rapid decompression means that the software does not limit the decompression speed, and slow decompression means switching between rapid decompression and pressure holding at certain intervals.

[0077] Step A6: Correct the pressure control logic according to the torque difference between the left and right wheels. When the upper limit of torque deviation given by the main control strategy is... At that time, the braking pressure of the left and right wheels of a single axle and Should meet In the formula The distance between the left and right wheels of this axle. The brake disc braking coefficient represents the ratio of braking torque to braking pressure. Let be the rolling radius of the wheel, if This requires that the braking pressure on the left wheel does not exceed a certain value, i.e. ,if This limits the braking pressure of the right wheel to a certain value, namely... .

[0078] Step A7: If using Figure 2 The architecture shown requires further application of low-selection logic to the wheel. This is done by still using step five to calculate the control logic for the four wheels. For two wheels on the same side, the logic that is more inclined towards decompression is used (the order of decompression logic is fast decompression > slow decompression > pressure holding > pressure boosting). For example, if one wheel needs fast decompression and the other needs slow decompression, then fast decompression will be used for output.

[0079] IV. Modular Reference Speed ​​Calculation Method

[0080] Existing technologies for calculating the reference speed of a four-wheeled vehicle based on the wheel speed of the four wheels are very mature, such as using fuzzy logic methods or vehicle dynamics models. However, there is less focus on how to extend this to six wheels or even more. In order to meet the needs of modular expansion of ABS algorithms and braking systems, the reference speed should also be modularly expanded with minor modifications.

[0081] Step B1: Construct a six-wheel vehicle reference speed calculation method and convert it to a four-wheel calculation method. The existing four-wheel speed-based reference speed calculation method in the prior art is For a six-wheel vehicle, the reference speed of the first and second axes can be calculated as The reference speed of the second and third axes can be calculated as The reference speed of the entire vehicle can be calculated as This method has simple calculation logic and fully utilizes the speeds of the six wheels, providing higher precision and anti-disturbance capability compared to four-wheel-based calculation. However, the third and fourth wheels are used twice in the calculation, and if the wheel speeds of these two wheels are erroneous, the reference speed is more likely to be erroneous. Therefore, the variable can be considered to increase This method avoids the above problems but slightly increases the calculation amount.

[0082] Step B2: Split the multi-axle vehicle into a combination of 2-axle or 3-axle bodies (preferably split into a 2-axle combination), and then calculate the reference speed. For example, a 4-axle vehicle is split into 2+2, a 5-axle vehicle is split into 2+3, and a 6-axle vehicle is split into 2+2+2 (here, it can also be split into 3+3, but the calculation amount of a 3-axle vehicle is 3 times that of a 2-axle vehicle, assuming that the calculation amount of a 2-axle vehicle is 1, then the total calculation amount of 2+2+2 is 3, and the total calculation amount of 3+3 is 6). Let the reference speed of the i-th body be The vehicle reference speed is where is the total number of wheels of the i-th body, and for a 3-axle body, it is 6, and for a 2-axle body, it is 4, i.e., for a 3-axle body, the calculated reference speed has a larger weight.

[0083] Five, modular torque difference correction calculation method

[0084] For the yaw moment limit of the entire vehicle It should be split into the yaw moment limit of each axle (j represents the j-th axle) Obviously, the sum of the yaw moment limits of each axle should be less than the yaw moment limit of the entire vehicle. For convenience of description, assume i.e., at this time, it is desired to limit the left wheel pressure to be no greater than a certain value. If <0, the same logic can be used to limit the right wheel.

[0085] Step C1: Decompose the yaw moment of the entire vehicle into each axle according to n axes, .

[0086] Step C2: Determine which axes have reached the limit Calculate the number of axes that have reached the limit as m.

[0087] Step C3: for the axis not reaching the limit, record its current generated yaw moment difference as , then its maximum change of yaw moment at next time (limited by the response speed of the braking system) is , then its limit at next time is = .

[0088] Step C4: for the axis reaching the limit, its limit is calculated as .

[0089] Step C5: loop Step C2 to Step C5, update .

Claims

1. A braking anti-lock braking control method, characterized in that, Includes the following steps: Step A1, calculate the locking tendency of a single wheel: First, calculate the wheel slip ratio; Step A2: Calculate the differential value of the wheel speed, i.e., the instantaneous acceleration; then calculate the filtered wheel acceleration using mean filtering. Step A3: Calculate the vehicle acceleration using the same method as wheel acceleration calculation; Step A4: Calculate the fuzzy logic for the degree of lock-in; Step A5: Based on fuzzy logic, switch to single-wheel pressure control; Step A6: Correct the pressure control logic according to the torque difference between the left and right wheels; Step A4 specifically includes: First, fuzzy logic 1, This is an index indicating an increased degree of wheel lock-up. When the degree of wheel lock-up is increased, the wheel slip ratio is larger, or the deceleration of the wheel is greater than the deceleration of the whole vehicle, or the deceleration of the wheel has exceeded the deceleration of the whole vehicle. Set the expression for fuzzy large as Where a, b, and x are variables; Set the expression for fuzzy small as , Fuzzy or logical Where γ represents a variable, and max(*) represents taking the maximum value between variables x and y; Fuzzy logic is ; where min(*) represents taking the minimum value of variables x and y; Then condition 1 is calculated as follows: s i For the slip ratio of the wheel, Condition 2 is calculated as follows , where a i This represents the acceleration of the i-th wheel. Indicates the acceleration of the entire vehicle; Condition 3 is calculated as follows , but Represented as ; Fuzzy Logic 2 This is an index indicating insufficient braking pressure. When braking pressure is too low, the speed of the wheels is close to the speed of the entire vehicle, meaning the slip ratio is small, or the wheel deceleration is close to the deceleration of the entire vehicle. Then condition 1 is calculated as follows: , Condition 2 is calculated as follows , but ; Step A5 specifically includes: when When this condition is met, it indicates that the braking pressure is very low and requires rapid pressure increase; when... When the condition is met, it indicates that the braking pressure is too low, so the pressure should be increased slowly; when... This indicates a high degree of seizure, requiring rapid decompression; when This indicates a relatively small degree of seizure, requiring slow decompression; when This indicates that the braking pressure is appropriate at this point and should be maintained. , , , as well as Both represent thresholds and satisfy the following conditions: , ; Step A6 specifically includes: when the upper limit of torque deviation given by the main control strategy is... At that time, the braking pressure of the left and right wheels of a single axle and Should meet In the formula The distance between the left and right wheels of this axle. The brake disc braking coefficient represents the ratio of braking torque to braking pressure. Let be the rolling radius of the wheel, if This requires that the braking pressure on the left wheel does not exceed a certain value, i.e. ,if This limits the braking pressure of the right wheel to a certain value, namely... .

2. The anti-lock braking control method according to claim 1, characterized in that, The invention relates to a modularly expandable braking system, comprising a modularly expandable braking unit, wherein the modularly expandable braking unit includes multiple braking modules based on shafts as basic units, each of the braking modules is powered by the same battery, each of the braking modules is supplied with air by the same air tank, and each of the braking modules is connected to the same main control ECU for communication; the main control ECUs of each modularly expandable braking unit form a star-shaped communication network, and the star-shaped communication networks communicate with each other. The braking module includes a braking pressure module, brake wheel cylinders, and wheel speed sensors. The braking pressure module includes a first brake output port and a second brake output port. The first brake output port and the second brake output port are respectively connected to at least one brake wheel cylinder. The braking pressure module controls the actual pressure of the brake wheel cylinders based on the braking pressure of each wheel received from the vehicle network.

3. The anti-lock braking control method according to claim 1, characterized in that, When the first brake output port and the second brake output port are connected to two brake wheel cylinders respectively, the brake wheel cylinders connected to the same brake output port are two wheels on the same side.

4. A method for calculating reference vehicle speed, characterized in that, A modularly expandable braking system applied to the anti-lock braking control method of claim 2 or 3 above provides a speed reference for determining wheel status, comprising the following steps: Step B1: Construct a method for calculating the reference speed of a 6-wheeled vehicle and convert it into a 4-wheeled calculation method; denoted as the method for calculating the reference speed based on the four-wheel speed. For a six-wheeled vehicle, the speed is calculated by referring to the reference speed of the four wheels on the first and second axles. The reference speeds for the second and third axles are calculated as follows: Then the reference speed of the whole vehicle is calculated as follows: Add variables ,but Where v1, v2, v3, v4, v5, and v6 represent the left wheel of the first axle, the right wheel of the first axle, the left wheel of the second axle, the right wheel of the second axle, the left wheel of the third axle, and the right wheel of the third axle, respectively. Step B2: Disassemble the multi-axle vehicle into combinations of 2-axle or 3-axle vehicle bodies, and then calculate the reference vehicle speed; let the reference vehicle speed of the i-th vehicle body be denoted as . The reference speed of the vehicle is In the formula Let be the total number of wheels of the i-th vehicle body.

5. A method for calculating torque difference correction, characterized in that, A modularly expandable braking system applied to the anti-lock braking control method of claim 2 or 3 above includes the following steps: For the yaw moment limitation of the whole vehicle It should be broken down into yaw moment limits for each axis. , j represents the j-th axis; Step C1: Decompose the yaw moment of the entire vehicle into n axes and distribute it to each axle. ; Step C2: Determine which axes have reached the limit The number of axes that reach the limit is calculated to be m; Step C3: For shafts that have not reached the limit, record the current difference in yaw moment as... Then the maximum change in its yaw moment at the next moment is Then the constraint quantity at the next moment is = ; Step C4: For axes that have reached the limit, the limit amount is calculated as follows: ; Step C5: Repeat steps C2 through C5, updating... .

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