Air pressure ABS brake pressure calculation system

Abstract

The invention discloses an air pressure ABS brake pressure calculation system, and relates to the technical field of drive-by-wire chassis. The system comprises a slip rate calculation module used for calculating the slip rate of wheels; the wheel deceleration calculation module is used for calculating the deceleration of the wheel and filtering; the state monitoring module is used for judging the state of the wheels according to the slip rate, the wheel deceleration and the vehicle speed; the basic target braking force calculation module is used for calculating the target braking force in the initial state; the output target braking force calculation module is used for calculating and processing the target braking force according to the state of the wheels; and the target braking force filtering module is used for filtering the target braking force according to the pressure increasing and decreasing states of the wheels. According to the technical scheme, the stable braking function of the air pressure ABS braking system of the commercial vehicle under different road surface conditions can be achieved, and the high application value is achieved.

Description

[0001] This application is a divisional application of a Chinese patent application with the application number "202411864437.X", the application date "December 18, 2024", and the invention title "A Pneumatic ABS Braking Pressure Calculation System and Method". Technical Field

[0002] The present invention relates to the technical field of by-wire chassis, and particularly to a pneumatic ABS braking pressure calculation system. Background Art

[0003] As a production tool, commercial vehicles drive economic development. Due to their complex usage scenarios, safety accidents frequently occur during the use of commercial vehicles. How to improve the safety of commercial vehicles has become a major problem in the production process of commercial vehicles. As one of the active safety devices of vehicles, the anti-lock braking system adjusts the wheel locking degree by controlling the braking torque according to the wheel speed feedback, can make full use of the road adhesion and ensure the stability of the vehicle during emergency braking, which is crucial for improving the safety of the vehicle. Existing commercial vehicles usually use compressed air as the power source to perform braking control on the vehicle. The equipped ABS braking system uses the method of target slip rate control, estimates the friction coefficient of the current road surface based on the slip rate and the recovery of the wheel speed, and thus calculates the target braking force of a single wheel to perform braking control on the vehicle. However, due to the unstable actual pressure response of the air pressure, the estimation of the friction coefficient is prone to deviation, and the ABS braking system frequently triggers pressure reduction or pressure increase, resulting in unstable braking intensity of the braking system. Therefore, the research and development of a simple and efficient method to improve the stability of the pneumatic ABS braking system of commercial vehicles under different road conditions is imminent.

[0004] Currently, most of the existing methods that can improve the stability of the pneumatic ABS braking system of commercial vehicles under different road conditions have certain defects in one aspect. For example, the method based on the electronic braking system controls the pressure of the brake chamber through an electronic control unit and an axle control module, which can accurately control the braking force, but this method has the problems of high cost and over-reliance on the electronic system. Therefore, based on this problem, this application proposes a pneumatic ABS braking pressure calculation system. Summary of the Invention

[0005] Technical Objectives In order to solve the above problems, the purpose of the present invention is to provide a pneumatic ABS braking pressure calculation system, which solves the problem that the stability of the pneumatic ABS braking system of commercial vehicles is easily affected under different road conditions. The application scenarios of this system and method are extensive, ensuring the braking intensity of the braking system under different road conditions, reducing the response time of the target braking force and the adjustment time of the system, and eliminating the phenomenon of abrupt braking.

[0006] Technical solution To achieve the above object, the present invention provides a pneumatic ABS braking pressure calculation system, which differentiates the states of wheels according to the slip ratio and deceleration of the wheels, determines the control mode of coaxial wheels according to the states of the wheels and the actual wheel cylinder pressure difference, and adjusts the braking pressure in a timely manner according to different states of the wheels. When the wheels have a tendency to slip, the braking pressure is adjusted according to the actual wheel cylinder pressure of the wheels. When the wheels have entered the slipping state, the braking pressure is adjusted according to the comparison result between the actual slip ratio and the target slip ratio, thereby realizing the stable braking function of the pneumatic ABS braking system of commercial vehicles under different road conditions.

[0007] In a first aspect, the present invention provides a pneumatic ABS braking pressure calculation system, comprising: A slip ratio calculation module for calculating the slip ratio of the wheels; A wheel deceleration calculation module for calculating the deceleration of the wheels and performing filtering; A state monitoring module for determining the state of the wheels according to the slip ratio, wheel deceleration and vehicle speed; A basic target braking force calculation module for calculating the target braking force in the initial state; An output target braking force calculation module for calculating and processing the target braking force according to the state of the wheels; A target braking force filtering module for filtering the target braking force according to the pressure increasing and decreasing state of the wheels.

[0008] Further, the state of the wheels is determined according to the slip ratio of the wheels and the deceleration of the wheels.

[0009] Furthermore, the calculation logic of the slip ratio of the wheels is that the difference between the vehicle speed and the wheel speed is divided by the vehicle speed and then multiplied by one hundred percent. Zero percent means the wheels do not slip, and one hundred percent means the wheels are completely locked; the calculation logic of the wheel deceleration is to differentiate the wheel speed, and the differential value is filtered by the Kalman filter algorithm, and the filtered result is the final wheel deceleration value.

[0010] Further, the states of the wheels include a non-slip state, a state with a tendency to slip, and a slipping state; the states of the wheels are determined according to the magnitude of the slip ratio and the magnitude of the wheel deceleration.

[0011] Furthermore, when the slip ratio is 0 and the wheel deceleration is greater than a certain threshold, the wheels are determined to be in a non-slip state; when the slip ratio is greater than 0 and less than a certain threshold and the wheel deceleration is greater than a certain threshold, the wheels are determined to be in a state with a tendency to slip; when the slip ratio is greater than a certain threshold and the wheel deceleration is less than a certain threshold, the wheels are determined to be in a slipping state.

[0012] Further, the target braking force in the initial state, i.e., the braking force generated when the ABS braking system is just triggered, is calculated as the vehicle mass multiplied by the target deceleration, multiplied by the tire rolling radius, and divided by the wheel cylinder braking coefficient.

[0013] Further, the pressure increase and decrease states of the wheel include a pressure increase state, a pressure decrease state, and a pressure holding state; the filtering algorithm is a variable step - slope filtering, and the filtering coefficient depends on the vehicle speed and the type of pressure increase and decrease.

[0014] Further, when two wheels on the same axle are in a state of having a tendency to slip, the control mode of this axle is determined according to the actual wheel cylinder pressure difference between the two wheels at this time; if the actual wheel cylinder pressure difference is small, the wheels enter the independent control mode, and the target braking pressure of each wheel is calculated separately; if the actual wheel cylinder pressure difference is large, the wheels enter the low - select control mode, and at this time, the target braking pressures of the two wheels are the same and are calculated according to the target braking pressure of the wheel on the low - adhesion road surface side. It improves the stability of the vehicle during emergency braking, reduces the risk of vehicle out - of - control caused by wheel lock - up; improves the driving performance of the vehicle on wet or uneven road surfaces; enhances the stability of the vehicle during curve driving or obstacle avoidance operations, and improves driving comfort.

[0015] Further, when the wheel is in a non - slipping state, its target braking force is calculated according to the vehicle target deceleration corresponding to the brake pedal and the vehicle parameters according to the high - adhesion road surface; when the wheel enters a state of having a tendency to slip, its target braking force is calculated according to the actual wheel cylinder pressure at the instant when the wheel enters the state of having a tendency to slip; when the wheel is in a state of having a tendency to slip, if its actual slip ratio is less than the target slip ratio, a feed - forward compensation braking pressure and a feedback pressure are added to the current actual braking force and a time delay is performed, if its actual slip ratio is greater than the target slip ratio, the feed - forward compensation braking pressure and the feedback pressure are reduced from the current actual braking force and a time delay is performed. By adjusting the braking pressure in a way that combines feed - forward compensation and feedback control, it can reduce the braking distance and improve the braking efficiency of the vehicle; a time - delay mechanism is introduced when adjusting the braking pressure, and the braking pressure is adjusted smoothly to reduce the impact brought by the braking process and improve the riding comfort.

[0016] Further, the system also includes an intelligent braking module, which is used to calculate the required braking pressure according to the sensor signals and through the electronic control unit, and adjust the pressure of the brake chamber by controlling the brake pressure regulator. It can intelligently select the combination form of mechanical braking and electric braking according to the vehicle state and driving conditions, improve the reliability and safety of the system, and provide the necessary technical support for autonomous driving.

[0017] Furthermore, the system further includes a dynamic matrix control module, which is used to analyze the dynamic characteristics of the target braking force, and perform optimization calculations within the control cycle through a rolling optimization strategy to determine the control strategy for a period of time in the future. It adjusts the braking strategy in real time through a rolling optimization and feedback correction mechanism to adapt to changes in vehicle state and road surface conditions, reduces the braking distance, improves the active safety of the vehicle, and enhances the stability and reliability of the system when facing non-linear characteristics.

[0018] In a second aspect, the present invention also provides a method for calculating the air pressure ABS braking pressure. The method is based on the system described in the first aspect above and includes: Determine the state of the wheel according to the slip ratio and deceleration of the wheel; Calculate and process the target braking force according to the state of the wheel; Filter the target braking force according to the pressure increase and decrease state of the wheel; Finally, obtain the air pressure ABS braking pressure.

[0019] In a third aspect, the present invention also provides a computer device, including a processor and a memory. The processor is connected to the memory. The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory so that the computer device implements the method for calculating the air pressure ABS braking pressure described above.

[0020] In a fourth aspect, the present invention also provides a computer-readable storage medium. A computer program is stored in the computer-readable storage medium. When the computer program is executed by a processor, the method for calculating the air pressure ABS braking pressure described above is implemented.

[0021] The present invention differentiates the state of the wheel according to the slip ratio and deceleration of the wheel, and determines the control mode of the coaxial wheels according to the state of the wheel and the actual wheel cylinder pressure difference; adjusts the braking pressure in a timely manner according to different states of the wheel, adjusts the braking pressure according to the actual wheel cylinder pressure of the wheel when the wheel has a tendency to slip, and adjusts the braking pressure according to the comparison result of the actual slip ratio and the target slip ratio when the wheel has entered the slipping state; the intelligent braking module can calculate the required braking pressure according to the sensor signals and through the electronic control unit, and adjust the pressure of the brake chamber by controlling the braking pressure regulator; the dynamic matrix control module can analyze the dynamic characteristics of the target braking force, and perform optimization calculations within the control cycle through a rolling optimization strategy to determine the control strategy for a period of time in the future. The system and method solve the problem that the stability of the air pressure ABS braking system of commercial vehicles is easily affected under different road surface conditions. The application scenarios of the system and method are wide, which ensures the braking intensity of the braking system under different road surface conditions, reduces the response time of the target braking force and the adjustment time of the system, and eliminates the phenomenon of sudden braking.

[0022] Beneficial effects By implementing the air pressure ABS braking pressure calculation system and method provided by the present invention as described above, the following technical effects are achieved: (1) Differentiate the states of wheels according to the slip ratio and deceleration of the wheels, and determine the control mode of coaxial wheels according to the states of the wheels and the actual wheel cylinder pressure difference; this improves the stability of the vehicle during emergency braking, reduces the risk of vehicle out of control caused by wheel locking; improves the driving performance of the vehicle on wet or uneven roads; enhances the stability of the vehicle during curve driving or obstacle avoidance operations, and improves driving comfort.

[0023] (2) Adjust the braking pressure in a timely manner according to different states of the wheels. When the wheels have a tendency to slip, adjust the braking pressure according to the actual wheel cylinder pressure of the wheels. When the wheels have entered the slipping state, adjust the braking pressure according to the comparison result between the actual slip ratio and the target slip ratio; it adjusts the braking pressure through a combination of feedforward compensation and feedback control, which can reduce the braking distance and improve the braking efficiency of the vehicle; a delay mechanism is introduced when adjusting the braking pressure, and the braking pressure is adjusted smoothly to reduce the impact brought by the braking process and improve the riding comfort.

[0024] (3) The intelligent braking module can calculate the required braking pressure based on sensor signals and through the electronic control unit, and adjust the pressure of the brake air chamber by controlling the braking pressure regulator; it can intelligently select the combination form of mechanical braking and electric braking according to the vehicle state and driving conditions, improve the reliability and safety of the system, and provide the necessary technical support for autonomous driving.

[0025] (4) The dynamic matrix control module can analyze the dynamic characteristics of the target braking force, and perform optimization calculations through a rolling optimization strategy within the control period to determine the control strategy for a future period of time; it adjusts the braking strategy in real time through a rolling optimization and feedback correction mechanism to adapt to changes in vehicle state and road conditions, reduces the braking distance, improves the active safety of the vehicle, and improves the stability and reliability of the system when facing non-linear characteristics. Brief description of the drawings

[0026] To make the above air pressure ABS braking pressure calculation system and method of the present invention more obvious and understandable, the drawings required for the specific implementation manners of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative efforts.

[0027] Figure 1 It shows a schematic diagram of the air pressure ABS braking pressure calculation system; Figure 2Schematic diagram showing the air pressure ABS braking pressure calculation method Figure 3 Schematic diagram showing the control process for coordinating the wheel braking pressure Figure 4 Schematic diagram showing the calculation process of the braking pressure of a single wheel Detailed implementation method

[0028] Example 1 Provided is an air pressure ABS braking pressure calculation system and method. The pressure calculation system is as shown in Figure 1 and the pressure calculation method is as shown in Figure 2 . Among them, the system includes: a slip ratio calculation module, a wheel deceleration calculation module, a state monitoring module, a basic target braking force calculation module, an output target braking force calculation module, and a target braking force filtering module, which are specifically as follows

[0029] The slip ratio calculation module is used to calculate the slip ratio of the wheel. The calculation logic of the slip ratio of the wheel is that the difference between the vehicle speed and the wheel speed is divided by the vehicle speed and then multiplied by 100%. 0% means the wheel is not slipping, and 100% means the wheel is completely locked

[0030] The wheel deceleration calculation module is used to calculate the deceleration of the wheel and perform filtering. The calculation logic of the deceleration of the wheel is to differentiate the wheel speed, and the differential value is filtered through the Kalman filter algorithm. The filtered result is the final wheel deceleration value

[0031] The state monitoring module is used to determine the state of the wheel according to the slip ratio, wheel deceleration, and vehicle speed. The states of the wheel include a non-slip state, a state with a tendency to slip, and a slip state. The state of the wheel is determined according to the slip ratio and deceleration of the wheel: when the slip ratio is 0 and the wheel deceleration is greater than a certain threshold, the wheel is determined to be in a non-slip state; when the slip ratio is greater than 0 and less than a certain threshold, and the wheel deceleration is greater than a certain threshold, the wheel is determined to be in a state with a tendency to slip; when the slip ratio is greater than a certain threshold and the wheel deceleration is less than a certain threshold, the wheel is determined to be in a slip state

[0032] The basic target braking force calculation module is used to calculate the target braking force in the initial state. The target braking force in the initial state is the braking force generated when the ABS braking system is just triggered. Its calculation logic is that the vehicle mass is multiplied by the target deceleration, the tire rolling radius is divided by the wheel cylinder braking coefficient

[0033] The output target braking force calculation module is used to calculate and process the target braking force according to the state of the wheel

[0034] The target braking force filtering module is used to filter the target braking force according to the pressure increase and decrease state of the wheel; the pressure increase and decrease state of the wheel includes the pressure increase state, the pressure decrease state and the pressure holding state; the filtering algorithm is variable step - slope filtering, and the filtering coefficient depends on the vehicle speed and the type of pressure increase and decrease.

[0035] The control process of the wheel braking pressure coordination is as follows Figure 3 shown. The wheel speed and vehicle speed signals pass through the slip ratio calculation and wheel deceleration calculation module to calculate the slip ratio and wheel deceleration of each wheel. Taking the front axle as an example, the slip ratio and wheel deceleration signals of the FR (front - engine rear - wheel drive) and FF (front - engine front - wheel drive) wheels are respectively input into the FR and FF state monitoring modules. This module determines the current state of the wheel according to the slip ratio and wheel deceleration. When the two wheels are in a state of having a tendency to slip, the actual wheel cylinder pressures when the two wheels are in a state of having a tendency to slip are respectively recorded and compared. According to the actual wheel cylinder pressure difference when the two wheels on the same axle are in a state of having a tendency to slip, it is segmented and the control mode of this axle is determined. If the actual wheel cylinder pressure difference when the two wheels are in a state of having a tendency to slip is small, it indicates that the road adhesion of the left and right wheels is not very different, and the left and right wheels enter the independent control mode, and their target braking pressures are calculated separately for each wheel. If the actual wheel cylinder pressure difference when the two wheels are in a state of having a tendency to slip is large, it indicates that the road adhesion of the left and right wheels is quite different, and the left and right wheels enter the low - selection control mode. At this time, the target braking pressures of the two wheels are the same and are calculated according to the target braking pressure of the wheel on the low - adhesion road surface side. The working principle of the rear axle is the same as that of the front axle.

[0036] The calculation process of the braking pressure of a single wheel is as follows Figure 4As shown, the wheel speed and vehicle speed signals pass through the slip ratio calculation and wheel deceleration calculation modules to calculate the slip ratio and wheel deceleration of each wheel. Taking a single wheel from a uniform high-adhesion road surface to a uniform low-adhesion road surface and then back to a uniform high-adhesion road surface as an example, when the driver steps on the brake, the system monitors the state of the wheel in real time based on the calculated slip ratio and wheel deceleration of the wheel, and calculates the required target braking force according to the different states of the wheel. When the wheel is in a non-slip state, its target braking force is calculated according to the vehicle target deceleration corresponding to the brake pedal and vehicle parameters on a high-adhesion road surface. When the wheel shows a tendency to lock on a uniform low-adhesion road surface, the target braking force of the wheel is calculated based on the actual wheel cylinder pressure at the instant when the wheel enters the state of having a tendency to slip. The main control target of the system when the wheel is in the state of having a tendency to slip is the target slip ratio of the wheel. If its actual slip ratio is less than the target slip ratio, a feedforward compensation braking pressure and a feedback pressure are increased on the basis of the current actual braking force and a time delay is performed. If its actual slip ratio is greater than the target slip ratio, the feedforward compensation braking pressure and the feedback pressure are reduced on the basis of the current actual braking force and a time delay is performed to ensure that the actual slip ratio of the wheel is within the target range. When the vehicle goes from a uniform low-adhesion road surface to a uniform high-adhesion road surface, the state of the wheel changes from the state of having a tendency to slip to the non-slip state, and at this time its target braking force is recalculated according to the calculated value in the non-slip state.

[0037] The system further includes an intelligent braking module for calculating the required braking pressure according to the sensor signals and through the electronic control unit, and adjusting the pressure of the brake chamber by controlling the brake pressure regulator, specifically including: solving the compatibility problem between the intelligent braking system and the pneumatic braking system through a pneumatic braking structure; collecting vehicle state information in real time through sensors and transmitting the sensor data to the electronic control unit through the CAN bus; calculating the required braking pressure in real time through the electronic control unit and establishing a calculation model of the braking pressure according to the pneumatic characteristics and pressure response; formulating corresponding control strategies according to the driver's braking intention and external conditions and through the calculation model, and finally transmitting the calculated braking pressure to each brake chamber through the electro-hydraulic brake master valve; the application of the intelligent braking scheme can reduce the response time of the pneumatic ABS braking system from about 600 milliseconds to within 150 milliseconds.

[0038] Embodiment 2: On the basis of the foregoing embodiment, the system is additionally provided with a dynamic matrix control module to realize the dynamic characteristic analysis of the target braking force, and optimize the calculation within the control period through a rolling optimization strategy to determine the control strategy for a future period of time; Among them, the dynamic characteristics of the pneumatic ABS braking pressure are described by the relationship between the braking pressure and the braking time, specifically as:

[0039] Among them, represents the braking pressure at time . represents the proportionality coefficient, which is related to the pressure increasing rate of the braking system; represents the attenuation coefficient, which is related to the pressure attenuation rate of the braking system; represents the steady-state pressure, that is, the value when the braking pressure reaches stability.

[0040] A prediction model is constructed through the step response sequence of the system to predict the future output of the system under different control inputs:

[0041] Among them, represents the prediction of the system output at time , that is, the predicted value of the braking pressure; represents the initial prediction value, which is predicted based on the current state and historical data; represents the dynamic matrix, which is composed of the step response sequence of the system; represents the control increment sequence, that is, the change in the control amount that needs to be applied at time ; represents the coefficient matrix related to the braking pressure; represents the change in the braking pressure, that is, the increment of the pressure during the braking process.

[0042] In each control cycle, according to the current system state and the prediction model, an optimization algorithm is used to calculate the optimal control increment sequence. The objective function is defined in quadratic form, and the optimal control increment is obtained through quadratic calculation:

[0043] Among them, represents the optimal control increment, which is the optimal control increment at the current time obtained through the optimization algorithm and is used to achieve the optimal adjustment of the system state; represents the output weight matrix, which is used to adjust the weight of the prediction error in the optimization objective function; represents the control weight matrix, which is used to adjust the weight of the control increment in the optimization objective function; represents the braking pressure control weight matrix, which is used to adjust the priority of the braking pressure control; represents the reference trajectory, that is, the desired system output; represents the predicted system output.

[0044] After the control increment, by collecting the real-time output data of the system and comparing it with the prediction model to correct the prediction model, the corrected model prediction value is:

[0045] Among them, represents the predicted value of the corrected model, considering error correction; represents the predicted value of the model at time , without considering error correction; represents the error weighting sequence, used to adjust the influence of errors in the prediction model; represents the non-linear correction term, used to handle non-linear errors; represents the error between the predicted output and the actual output.

[0046] Apply the calculated control increment to the system to achieve precise control of the air pressure ABS braking pressure.

[0047] For example, assume there is a linear system, whose dynamic matrix is , and the control input influence matrix is ; set the weight matrix to be , and the control weight matrix to be ; the desired output ; the current output ; the current control increment ; Prediction model calculation:

[0048] Rolling optimization calculation:

[0049]

[0050]

[0051] Assume is the error vector, is the predicted output, and perform correction.

[0052] The effect of the dynamic matrix control scheme is shown in Table 1: Table 1. Summary of the effect of the dynamic matrix control scheme

[0053] As shown in Table 1, after the model is optimized by the dynamic matrix control scheme, the braking pressure control accuracy is significantly improved, and the error is greatly reduced; this shows that the dynamic matrix control scheme can significantly improve the accuracy of the air pressure ABS braking pressure calculation method.

[0054] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable non-transitory storage media containing computer-usable program code.

[0055] The present invention can provide computer program instructions to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, such that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the system.

[0056] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, such that the instructions stored in the computer-readable memory generate a manufactured article including instruction means that implement the functions of the system.

[0057] These computer program instructions can also be loaded onto a computer or other programmable data processing device, such that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process, and thus the instructions executed on the computer or other programmable device provide steps for implementing the functions of the system.

Claims

1. A pneumatic ABS brake pressure calculation system, characterized in that: include: A slip rate calculation module, used for calculating the slip rate of the wheel; Wheel deceleration calculation module, used to calculate the deceleration of the wheel and perform filtering; A state monitoring module is used to determine the state of the wheel based on the slip rate, wheel deceleration and vehicle speed; A basic target braking force calculation module, used to calculate the target braking force in the initial state; Output target braking force calculation module, used to calculate and process the target braking force according to the state of the wheel; The target braking force filtering module is used to filter the target braking force according to the pressure increase or decrease state of the wheel.

2. The pneumatic ABS brake pressure calculation system according to claim 1, characterized in that: The states of the wheels include a non-slip state, a slip tendency state and a slip state; the states of the wheels are determined based on the magnitude of the slip rate and the magnitude of the wheel deceleration.

3. The pneumatic ABS brake pressure calculation system according to claim 2, characterized in that: When two coaxial wheels are in a state of slipping tendency, the control mode of the axle is determined according to the actual wheel cylinder pressure difference between the two wheels at this time; if the actual wheel cylinder pressure difference is small, the wheel enters the independent control mode, and each wheel calculates its target braking pressure separately; if the actual wheel cylinder pressure difference is large, the wheel enters the low-select control mode, and the target braking pressures of the two wheels are the same and are calculated according to the target braking pressure of the wheel on the low-adhesion road surface side.

4. The pneumatic ABS brake pressure calculation system according to claim 2, characterized in that: When the wheel is in a non-skidding state, its target braking force is calculated according to the target vehicle deceleration corresponding to the brake pedal and the vehicle parameters according to the high adhesion road surface; when the wheel enters a skidding tendency state, its target braking force is calculated according to the actual wheel cylinder pressure at the moment the wheel enters the skidding tendency state; when the wheel is in a skidding tendency state, if its actual slip rate is less than the target slip rate, the feedforward compensation braking pressure and feedback pressure are increased on the basis of the current actual braking force and a delay is performed; if its actual slip rate is greater than the target slip rate, the feedforward compensation braking pressure and feedback pressure are reduced on the basis of the current actual braking force and a delay is performed.

5. The pneumatic ABS brake pressure calculation system according to any one of claims 1 to 4, characterized in that: The system further comprises an intelligent brake module, which is used for calculating the required brake pressure according to the sensor signal through the electronic control unit and adjusting the pressure of the brake air chamber by controlling the brake pressure regulator.

6. The pneumatic ABS brake pressure calculation system according to any one of claims 1 to 4, characterized in that: The system also includes a dynamic matrix control module for realizing dynamic characteristic analysis of target braking force and performing optimization calculation within a control cycle through a rolling optimization strategy to determine a control strategy for a period of time in the future.

7. The pneumatic ABS brake pressure calculation system according to claim 6, characterized in that: The dynamic characteristics of air ABS brake pressure are described by the relationship between brake pressure and braking time, specifically: in, Indicates at time Braking pressure at It represents the proportionality factor, which is related to the pressure increase rate of the brake system; Represents the attenuation coefficient, which is related to the pressure decay rate of the brake system; Indicates steady-state pressure, that is, the value when the brake pressure reaches stability.

8. The pneumatic ABS brake pressure calculation system according to claim 7, characterized in that: The prediction model is constructed through the system's step response sequence to predict the future output of the system under different control inputs: in, Indicates at time The system output prediction, i.e. the predicted value of the brake pressure; Represents the initial forecast value, which is based on the current state and historical data; represents the dynamic matrix, which is composed of the step response sequence of the system; Represents the control increment sequence, that is, at time Changes in the amount of control that needs to be applied; represents the coefficient matrix related to brake pressure; Indicates the change in brake pressure, that is, the increase in pressure during the braking process.

9. The pneumatic ABS brake pressure calculation system according to claim 8, characterized in that: In each control cycle, the optimization algorithm is used to calculate the optimal control increment sequence according to the current system state and the prediction model. The objective function is defined in quadratic form, and the optimal control increment is obtained by quadratic calculation: in, Represents the optimal control increment, which is the optimal control increment at the current moment obtained by the optimization algorithm and is used to achieve the optimal adjustment of the system state; Represents the output weight matrix, which is used to adjust the weight of the prediction error in the optimization objective function; represents the control weight matrix, which is used to adjust the weight of the control increment in the optimization objective function; represents the brake pressure control weight matrix, which is used to adjust the priority of brake pressure control; represents the reference trajectory, i.e., the desired system output; Represents the predicted system output.

10. The pneumatic ABS brake pressure calculation system according to claim 9, characterized in that: After the control increment, the prediction model is corrected by collecting the real-time output data of the system and comparing it with the prediction model. The prediction value of the corrected model is: in, represents the corrected model prediction value, taking into account the error correction; Indicates at time The model prediction value of , without considering error correction; Represents the error weighted sequence, which is used to adjust the impact of errors in the prediction model; Represents the nonlinear correction term, which is used to deal with nonlinear errors; Represents the error between the predicted output and the actual output; The calculated control increment is applied to the system to achieve precise control of the air ABS brake pressure.

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