A vehicle brake control system using a proportional valve adjustment

Abstract

The application discloses a kind of vehicle brake control systems using proportional valve regulation, it is related to vehicle brake control technical field, including input processing module, control generation module, valve control module, model analysis module and closed-loop supervision module.System calculates target brake pressure by receiving brake request and vehicle state, and generates initial control signal of proportional valve accordingly.Valve control module drives proportional valve and monitors actual pressure change, model analysis module is corrected valve opening control strategy according to the comparison result of pressure change data and pre-stored model, to improve pressure tracking accuracy and system robustness.Closed-loop supervision module synchronously collects wheel speed and vehicle dynamic parameters, supervises and compensates pressure regulation process, realizes the collaborative optimization of brake control and vehicle stability control.The application improves the adaptability of brake pressure control and vehicle driving safety.

Description

Technical Field

[0001] This invention belongs to the field of vehicle braking control technology, specifically a vehicle braking control system that utilizes a proportional valve for adjustment. Background Technology

[0002] In vehicle braking systems, especially brake-by-wire systems, proportional valves are a common technique for regulating brake pressure. Existing solutions typically rely on classical control algorithms, using a proportional-integral-derivative (PID) controller to directly calculate and output the valve opening control signal. This method employs fixed control logic, with parameters often set based on ideal operating conditions or specific calibration states. However, when the braking system operates under complex nonlinear factors such as temperature variations in fluid characteristics, valve wear or manufacturing tolerances, and pipeline pressure fluctuations, fixed control parameters struggle to achieve accurate, rapid, and stable pressure tracking, potentially leading to pressure overshoot, slow response, or increased steady-state error.

[0003] Braking control and vehicle stability control are closely related in modern vehicles. In existing technical architectures, the basic brake pressure regulation module and vehicle dynamic control modules such as the anti-lock braking system (ABS) and electronic stability control system typically operate in layers or relatively independently. The basic braking module is responsible for executing pressure requests, while the advanced stability control module overrides or intervenes in the basic braking request when wheel slippage or vehicle instability is detected. This discrete or loosely coupled approach may lead to delays or conflicts in the generation, transmission, and execution of control commands. Under extreme conditions such as emergency braking or low-traction road surfaces, optimal coordination between brake pressure regulation and vehicle dynamics cannot be achieved, affecting braking performance and driving safety.

[0004] There is a need for an integrated solution that can overcome the nonlinear effects of the braking system itself, achieve high-precision pressure adaptive control, and deeply integrate basic braking adjustment with overall vehicle dynamic monitoring. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art;

[0006] Therefore, the present invention proposes a vehicle braking control system using a proportional valve, comprising:

[0007] The input processing module is used to receive vehicle braking request commands and obtain current vehicle driving status data, and calculate target braking pressure based on the vehicle braking request commands and the vehicle driving status data.

[0008] The control generation module is used to generate an initial proportional valve opening control signal based on the difference between the target braking pressure and the current actual braking pressure.

[0009] The valve control module is used to drive the proportional valve in the braking circuit to adjust the opening degree according to the initial proportional valve opening degree control signal, and to monitor the actual braking pressure change data caused by the opening degree change.

[0010] The model analysis module is used to compare and analyze the actual braking pressure change data with the pre-stored pressure-flow-valve opening relationship model, and correct the proportional valve opening control strategy based on the comparison and analysis results, so as to update the control signal so that the actual braking pressure follows the target braking pressure change.

[0011] The closed-loop monitoring module is used to continuously collect wheel speed signals and vehicle dynamic parameters during the brake pressure adjustment process, and to use the signals and parameters to perform closed-loop monitoring and compensation for the brake pressure adjustment process.

[0012] Furthermore, the acquisition of current vehicle driving status data specifically includes:

[0013] Vehicle speed signals, longitudinal acceleration signals, steering wheel angle signals, and yaw rate signals are collected through an onboard sensor network.

[0014] Read the status flags of the electronic stability program system and the activation status of the anti-lock braking system;

[0015] Acquire the real-time wheel speed pulse signal of each wheel and calculate the instantaneous slip ratio of each wheel;

[0016] The vehicle speed signal, longitudinal acceleration signal, steering wheel angle signal, yaw rate signal, status flag, activation status, real-time wheel speed pulse signal, and instantaneous slip ratio value are integrated to form the vehicle driving status data.

[0017] Furthermore, the calculation of the target braking pressure based on the vehicle braking request command and the vehicle driving state data specifically includes:

[0018] The vehicle braking request command is parsed to obtain the braking intensity required by the driver or the deceleration value requested by the advanced driver assistance system.

[0019] By combining the current vehicle speed and vehicle load information in the vehicle driving status data, a preset braking pressure benchmark mapping table is queried to obtain the basic braking pressure requirement.

[0020] Based on the steering wheel angle and yaw rate in the vehicle driving status data, the vehicle steering status is determined, and the steering condition is corrected for the basic braking pressure requirement.

[0021] Based on the activation status of the electronic stability program system or anti-lock braking system in the vehicle driving status data, the additional braking pressure required for dynamic stability control or the pressure modulation component required for anti-lock adjustment is superimposed.

[0022] By combining the basic braking pressure requirement, the steering condition correction, and the additional braking pressure or pressure modulation component, the target braking pressure finally applied to each wheel is calculated.

[0023] Furthermore, the step of generating an initial proportional valve opening control signal based on the difference between the target braking pressure and the current actual braking pressure specifically includes:

[0024] The current actual braking pressure of each brake wheel cylinder is obtained in real time by pressure sensors in the brake line;

[0025] For each wheel, calculate the pressure difference between the target braking pressure and the current actual braking pressure;

[0026] Based on the sign and magnitude of the pressure difference, determine the adjustment direction and adjustment intensity reference value of the proportional valve;

[0027] Based on the preset proportional valve opening-pressure change rate characteristic curve, the adjustment intensity reference value is converted into the corresponding pulse width modulation duty cycle or current command initial value.

[0028] The pulse width modulation duty cycle or the initial value of the current command is encapsulated into the initial proportional valve opening control signal, which includes the target proportional valve identifier and the corresponding control quantity.

[0029] Furthermore, the step of adjusting the opening of the proportional valve in the braking circuit based on the initial proportional valve opening control signal specifically includes:

[0030] The initial proportional valve opening control signal is sent to the corresponding proportional valve driver;

[0031] The proportional valve driver outputs a corresponding drive current to the electromagnetic coil of the target proportional valve according to the received control signal.

[0032] The electromagnetic coil generates electromagnetic force under the action of the driving current, which drives the valve core of the proportional valve to move against the spring preload.

[0033] The displacement of the valve core changes the flow area of ​​the throttling orifice inside the proportional valve, thereby adjusting the opening degree of the proportional valve.

[0034] The opening adjustment directly changes the flow resistance of brake fluid from the master cylinder to the wheel cylinder or from the wheel cylinder to the reservoir.

[0035] Furthermore, the monitoring of actual braking pressure changes caused by changes in brake opening specifically includes:

[0036] After the proportional valve opening adjustment begins, the pressure sensor signal of the brake wheel cylinder is acquired at a frequency higher than the conventional sampling rate.

[0037] Record the sequence of pressure sensor signals over time to obtain the original curve of pressure rise or fall;

[0038] The original curve is digitally filtered to remove high-frequency noise interference, resulting in a smooth pressure change curve.

[0039] Key features are extracted from the smooth pressure change curve, including the initial response time of the pressure change, the rise time to reach the steady value, the rate of pressure change, and the final stable pressure value.

[0040] The key features are associated with and stored along with the corresponding timestamps, proportional valve identifiers, and initial control signals to form the actual braking pressure change data.

[0041] Furthermore, the comparison and analysis of the actual braking pressure change data with the pre-stored pressure-flow-valve opening relationship model specifically includes:

[0042] Read the pressure change rate and the final stable pressure value under the current control signal from the actual braking pressure change data;

[0043] From the pre-stored pressure-flow-valve opening relationship model, query the theoretical pressure change rate and theoretical stable pressure value under the same ambient temperature and brake fluid characteristics.

[0044] Calculate the deviation between the pressure change rate and the theoretical pressure change rate, and calculate the deviation between the final stable pressure value and the theoretical stable pressure value;

[0045] Analyze whether the deviation exceeds the preset allowable range, and determine the cause of the deviation, such as the drift of the proportional valve response characteristics, leakage in the brake line, or air in the brake fluid.

[0046] Furthermore, the proportional valve opening control strategy based on the comparative analysis results specifically includes:

[0047] If the deviation is within the allowable range, the current opening control strategy is maintained, and only the model parameters are fine-tuned and updated.

[0048] If the deviation exceeds the allowable range and is determined to be a drift in the proportional valve response characteristics, then the mapping relationship of the pulse width modulation duty cycle or current command value in the proportional valve opening control signal is adjusted in reverse according to the magnitude and direction of the deviation.

[0049] If the deviation exceeds the allowable range and it is determined that there is a slow leak, a compensation component to maintain the opening is superimposed on the generated control signal to counteract the insufficient pressure maintenance caused by the leak.

[0050] If the deviation exceeds the allowable range and is determined to be due to air in the brake fluid, a correction strategy is generated that includes a small-amplitude oscillation opening signal at a specific frequency to promote the expulsion of air bubbles.

[0051] The adjustment and compensation rules adopted for different causes of deviation are integrated to form a corrected pulse width modulation duty cycle-target pressure relationship or current-pressure relationship, which serves as the new opening control strategy.

[0052] Furthermore, the closed-loop monitoring and compensation of the braking pressure regulation process using the aforementioned signals and parameters specifically includes:

[0053] During the brake pressure follow-up adjustment process, the slip ratio of each wheel based on the wheel speed signal is calculated in real time;

[0054] The slip ratio is compared with the optimal slip ratio range. If the slip ratio of a certain wheel is close to or exceeds the critical value, an anti-lock braking intervention signal is generated for the wheel proportional valve.

[0055] Simultaneously, the yaw rate and lateral acceleration in the vehicle dynamic parameters are analyzed. If they deviate too much from the expected values ​​based on the steering wheel angle, an electronic stability program intervention signal is generated.

[0056] The anti-lock braking intervention signal or the electronic stability program intervention signal serves as a higher priority superimposed instruction, temporarily overriding or modifying the current proportional valve opening control signal.

[0057] During the period when the intervention signal is in effect, relevant parameters are continuously monitored. Once the condition is lifted, proportional valve opening control based on the target braking pressure is restored.

[0058] Furthermore, the method for constructing the pre-stored pressure-flow-valve opening relationship model specifically includes:

[0059] In the hydraulic bench test environment of the vehicle braking system, the target proportional valve is installed in the simulated braking circuit;

[0060] Input a set of known and accurate pulse width modulation duty cycle or current command values ​​covering its operating range into the solenoid coil of the proportional valve, and record the corresponding valve core displacement as the actual opening degree.

[0061] At each stable opening degree, the steady-state flow rate of the brake fluid flowing through the proportional valve under different inlet pressures is measured by a flow meter, generating multiple sets of opening degree-pressure-flow data points;

[0062] Inside the environmental test chamber, the ambient temperature was changed and different types of brake fluid were used. The following measurement operations were repeated: a set of known and accurate pulse width modulation duty cycle or current command values ​​covering its operating range were input into the solenoid coil of the proportional valve, and the corresponding valve core displacement was recorded as the actual opening degree; at each stable opening degree, the steady-state flow rate of the brake fluid flowing through the proportional valve under different inlet pressures was measured by a flow meter, generating multiple sets of opening degree-pressure-flow rate data points, and obtaining a set of opening degree-pressure-flow rate data points under different temperatures and brake fluid characteristics;

[0063] Based on the data point set, a mathematical model is established through surface fitting or neural network training, with ambient temperature, brake fluid viscosity parameters, and target pressure change rate as inputs, and the required proportional valve theoretical opening degree or theoretical control current as outputs. The mathematical model is then stored as the pressure-flow-valve opening degree relationship model.

[0064] Compared with the prior art, the beneficial effects of the present invention are:

[0065] The model analysis module compares and analyzes real-time monitored actual braking pressure changes with the pre-stored pressure-flow-valve opening relationship model in the system. Based on the comparison results, it dynamically corrects the proportional valve opening control strategy and updates the control signal. This process identifies the deviation between the actual system characteristics and the model's expectations. By adjusting control parameters online, it directly compensates for internal parameter perturbations and external disturbances, significantly improving the tracking accuracy of the actual braking pressure to the target pressure. The steady-state error of pressure establishment is reduced, the response process is more stable, and overshoot and oscillation are suppressed. The system's adaptability to different operating conditions, ambient temperatures, and component wear states is enhanced, and control robustness is improved.

[0066] The closed-loop monitoring module continuously collects wheel speed signals and dynamic parameters such as vehicle yaw rate and lateral acceleration during brake pressure regulation. This information is used for real-time closed-loop monitoring and dynamic compensation of pressure regulation. This module integrates multi-source vehicle state data, enabling the system to simultaneously assess wheel-ground adhesion and vehicle stability trends while adjusting pressure. Based on the assessment results, compensation or correction commands are directly applied to the pressure control process, achieving functional integration of basic brake pressure regulation and vehicle dynamic stability control. The generation and changes in brake pressure directly serve to maintain optimal wheel-ground interaction and vehicle stability, improving the system's predictability and proactive intervention capabilities against wheel slippage or vehicle instability risks. Under complex operating conditions, the synergy between braking performance and vehicle handling stability is enhanced. Attached Figure Description

[0067] Figure 1 This is a timing diagram of the vehicle braking control system using a proportional valve as described in this invention.

[0068] Figure 2 A flowchart for calculating the target braking pressure;

[0069] Figure 3 A bar chart comparing key characteristics of pressure changes at each wheel of a vehicle's braking system;

[0070] Figure 4 A bar chart comparing pressure deviations in vehicle braking systems;

[0071] Figure 5 A bar chart comparing the braking pressure of each wheel before and after ESP intervention. Detailed Implementation

[0072] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0073] See Figure 1 During operation, the system's input processing module first receives vehicle braking request commands from the brake pedal sensor or advanced driver assistance system (ADAS), and simultaneously acquires current vehicle driving status data collected through the onboard sensor network. Based on these commands and data, this module determines the target braking pressure required for each wheel through internal calculation logic. Subsequently, the control generation module generates an initial proportional valve opening control signal based on the difference between the calculated target braking pressure and the current actual braking pressure fed back in real time by the pressure sensor. Upon receiving this control signal, the valve control module drives the proportional valve solenoid coil in the corresponding braking circuit, causing its valve core to displace and adjust the throttle opening, thereby changing the brake fluid flow rate. During this process, the valve control module also monitors the actual braking pressure changes caused by the opening changes through a high-frequency sampling pressure sensor. The model analysis module then performs real-time comparison and analysis of the monitored actual braking pressure change data with the pre-stored pressure-flow-valve opening relationship model in the system. Based on the identified deviations and their possible causes, the module corrects the current proportional valve opening control strategy online and updates the control signal sent to the valve control module accordingly, so that the actual braking pressure can more accurately follow the target braking pressure changes. Throughout the entire braking pressure regulation process, the closed-loop monitoring module continuously collects dynamic parameters such as wheel speed signals and vehicle yaw rate. It uses these signals and parameters to monitor the braking process and generates higher-priority intervention signals to compensate for proportional valve control when necessary, ensuring vehicle braking stability.

[0074] In one embodiment of the present invention, the input processing module acquires vehicle speed signals, longitudinal acceleration signals, steering wheel angle signals, and yaw rate signals through an onboard sensor network. Simultaneously, the input processing module reads the status flags of the electronic stability program system and the activation status of the anti-lock braking system from the vehicle bus network. The input processing module also acquires real-time wheel speed pulse signals emitted by the wheel speed sensors of each wheel, and calculates the instantaneous slip ratio of each wheel based on the real-time wheel speed pulse signals and the vehicle speed signal; the instantaneous slip ratio calculation formula is as follows:

[0075] ;

[0076] in: This represents the slip ratio of the i-th wheel. Indicates vehicle speed. This represents the angular velocity of the i-th wheel. This represents the effective rolling radius of the i-th wheel. The input processing module integrates vehicle speed signal, longitudinal acceleration signal, steering wheel angle signal, yaw rate signal, electronic stability program system status flag, anti-lock braking system activation status, real-time wheel speed pulse signal, and instantaneous slip ratio value to form a complete set of vehicle driving status data.

[0077] See Figure 2After obtaining vehicle driving status data, the input processing module parses the vehicle braking request command to obtain the driver's required braking intensity or the deceleration value requested by the advanced driver assistance system. Combining the current vehicle speed and vehicle load information from the driving status data, the input processing module queries a preset braking pressure benchmark mapping table to obtain the basic braking pressure requirement. Based on the steering wheel angle and yaw rate in the driving status data, the input processing module determines the vehicle's steering state and corrects the basic braking pressure requirement for steering conditions. This correction is achieved through a correction coefficient determined based on the difference between the steering wheel angle and the yaw rate. Based on the activation status of the electronic stability program system or anti-lock braking system in the driving status data, the input processing module superimposes the additional braking pressure required for dynamic stability control or the pressure modulation component required for anti-lock braking adjustment. In essence, the input processing module integrates the basic braking pressure requirement, the steering condition correction, and the additional braking pressure or pressure modulation component to calculate the final target braking pressure applied to each wheel. The calculation of the target braking pressure follows a linear superposition principle to ensure coordinated action of all components. In practical implementation, the basic braking pressure requirement is directly used as the benchmark after being looked up from the mapping table. The steering condition correction adjusts the benchmark as a percentage, while the additional braking pressure or pressure modulation component is superimposed as an absolute value. Optionally, the preset braking pressure benchmark mapping table is a three-dimensional lookup table, with dimensions including vehicle speed, vehicle load, and requested deceleration value. The mapping table is obtained through bench testing. In some embodiments, vehicle load information is indirectly estimated through a suspension height sensor or air spring pressure sensor, and this vehicle load information is used to adjust the lookup index of the braking pressure benchmark mapping table. It can be understood that the judgment logic for steering condition correction is based on a preset steering threshold value; when the absolute value of the steering wheel angle is greater than the threshold value and the ratio of yaw rate to steering wheel angle exceeds the expected range, the vehicle is determined to be in an oversteer or understeer state, thereby triggering steering condition correction. In practical implementation, the magnitude of the steering condition correction is proportional to the deviation of the steering wheel angle and yaw rate; the greater the deviation, the greater the correction. Optionally, the additional braking pressure required for dynamic stability control is calculated in real time by the control algorithm of the electronic stability program system, and the pressure modulation component is dynamically generated by the control algorithm of the anti-lock braking system based on the slip ratio deviation; the input processing module receives these components through the vehicle bus and directly superimposes them into the target braking pressure calculation.

[0078] In one embodiment of the present invention, the control generation module acquires the current actual braking pressure of each brake wheel cylinder in real time through pressure sensors installed in the brake lines; the pressure sensors installed in the brake lines convert the pressure analog signal into a digital signal at a fixed sampling frequency and transmit it to the control generation module. For each independently controlled wheel, the control generation module calculates the pressure difference between its target braking pressure and the current actual braking pressure, the pressure difference being defined as:

[0079] ;

[0080] in: This represents the pressure difference value corresponding to the j-th wheel. This represents the target braking pressure of the j-th wheel calculated by the input processing module. This represents the current actual braking pressure of the j-th wheel, as fed back by the pressure sensor. The control generation module determines the adjustment direction and adjustment intensity reference value of the proportional valve based on the sign and magnitude of the pressure difference. When the pressure difference is positive, the adjustment direction is to increase the proportional valve opening to increase braking pressure; when the pressure difference is negative, the adjustment direction is to decrease the proportional valve opening to decrease braking pressure. The adjustment intensity reference value is determined based on the absolute value of the pressure difference; the larger the absolute value, the larger the adjustment intensity reference value. In some embodiments, the control generation module converts the adjustment intensity reference value into the corresponding pulse width modulation duty cycle or current command initial value based on a preset proportional valve opening-pressure change rate characteristic curve. The proportional valve opening-pressure change rate characteristic curve describes the mapping relationship between the braking pressure change per unit time and the pulse width modulation duty cycle or drive current under specific system operating conditions. It can be understood that the control generation module encapsulates the pulse width modulation duty cycle or the initial value of the current command into an initial proportional valve opening control signal. This initial proportional valve opening control signal includes a target proportional valve identifier and the corresponding control quantity. The target proportional valve identifier specifies the specific proportional valve driver receiving the control signal, and the control quantity is the specific value of the calculated pulse width modulation duty cycle or the initial value of the current command. In specific implementations, the pressure difference calculation is performed synchronously within each control cycle, and the control cycle is synchronized with or an integer multiple of the sampling cycle of the pressure sensor. Optionally, a piecewise function strategy is used to determine the adjustment intensity reference value. For the absolute value of the pressure difference in different intervals, different gain coefficients are applied to optimize the dynamic response. In some embodiments, the proportional valve opening-pressure change rate characteristic curve is stored in the memory of the control generation module in the form of a two-dimensional data table. The data table is obtained through bench testing calibration, and the calibration process covers different initial pressure and ambient temperature conditions. The process of converting the regulation intensity reference value into the initial value of the pulse width modulation duty cycle or current command is a lookup and interpolation process. The control generation module queries the characteristic curve data table based on the current regulation intensity reference value and system state parameters, and calculates the accurate control quantity value through linear interpolation. In specific implementation, the encapsulated initial proportional valve opening control signal follows a specific vehicle network communication protocol. The signal frame contains a frame header, target address, control command data, and checksum to ensure the integrity and reliability of the signal during transmission. Optionally, for the pulse width modulation duty cycle control method, the control quantity value range is limited to 0% to 100%; for the current command control method, the control quantity value range is limited to the rated operating current range of the proportional valve solenoid coil.

[0081] In one embodiment of the present invention, the valve control module sends an initial proportional valve opening control signal to the corresponding proportional valve driver. Based on the received control signal, the proportional valve driver outputs a corresponding drive current to the solenoid coil of the target proportional valve. Under the action of the drive current, the solenoid coil generates an electromagnetic force, driving the valve core of the proportional valve to displace over the spring preload. This displacement of the valve core changes the flow area of ​​the internal throttling orifice of the proportional valve, thereby adjusting the opening of the proportional valve. This opening adjustment directly changes the flow resistance of brake fluid from the master cylinder to the wheel cylinder or from the wheel cylinder to the reservoir.

[0082] After the proportional valve opening adjustment begins, the valve control module acquires pressure sensor signals from the brake wheel cylinders at a frequency higher than the conventional sampling rate. The module records the sequence of pressure sensor signal changes over time, obtaining the raw curve of pressure rise or fall. The module performs digital filtering on the raw curve to remove high-frequency noise interference, resulting in a smooth pressure change curve. The module extracts key features from the smooth pressure change curve, including the initial response time of the pressure change, the rise time to reach the stable value, the pressure change rate, and the final stable pressure value. The module associates and stores the key features with the corresponding timestamp, proportional valve identifier, and initial control signal to form actual brake pressure change data. In specific implementation, the valve control module sends the initial proportional valve opening control signal to the corresponding proportional valve driver. The proportional valve driver, acting as a power amplification unit, receives digital or analog commands from the control generation module. Based on the received initial proportional valve opening control signal, the proportional valve driver outputs a corresponding drive current to the electromagnetic coil of the target proportional valve. The amplitude of the drive current is linearly or functionally related to the control quantity encapsulated in the initial proportional valve opening control signal. The electromagnetic coil generates an electromagnetic force under the action of a driving current. This electromagnetic force is proportional to the magnitude of the driving current. The electromagnetic force drives the valve core of the proportional valve to displace, overcoming the spring preload. The direction of the valve core's displacement depends on the polarity of the driving current or the adjustment direction specified in the initial proportional valve opening control signal. The displacement of the valve core changes the flow area of ​​the internal throttling orifice of the proportional valve, thus adjusting the valve opening. The relationship between the flow area and the valve core displacement is determined by the mechanical structure of the proportional valve. The opening adjustment directly changes the flow resistance of brake fluid from the master cylinder to the wheel cylinders or from the wheel cylinders to the reservoir. This change in flow resistance leads to a redistribution of fluid flow and pressure in the brake lines. It can be understood that there is a brief rise time in the driving current, and the valve core's displacement response also exhibits inertial hysteresis. The entire opening adjustment process is a dynamic electromechanical-hydraulic coupling process.

[0083] After the proportional valve opening adjustment begins, the valve control module acquires the pressure sensor signal from the brake wheel cylinder at a higher sampling rate than usual. This high sampling rate ensures the capture of transient details of pressure changes. The valve control module records the sequence of pressure sensor signal changes over time, obtaining the raw curve of pressure rise or fall. This raw curve contains inherent pressure pulsations and sensor noise inherent in the braking system. Digital filtering is performed on the raw curve to remove high-frequency noise interference, resulting in a smooth pressure change curve. This digital filtering is implemented using a low-pass filter with a configurable cutoff frequency. Key features are extracted from the smooth pressure change curve, including the initial response time of the pressure change, the rise time to reach a stable value, the rate of pressure change, and the final stable pressure value. Calculation formula:

[0084] ;

[0085] in: This represents the final stable pressure value. This represents the pressure value at the moment the pressure change begins. This represents the rise time from the initial moment to reaching the final stable pressure value. In some embodiments, the high-frequency sampling rate is set to five times or more of the sampling rate of a conventional control system to ensure sufficient capture of transient pressure changes. The extracted key features are associated and stored with the corresponding timestamps, proportional valve identifiers, and initial control signals to form actual braking pressure change data. This data is temporarily stored in the buffer of the valve control module as an array of structures. Optionally, digital filtering uses a moving average filter or a Butterworth low-pass digital filter algorithm, with the filter parameters pre-calibrated based on the inherent frequency of the braking system. In some embodiments, the initial response time is defined as the time interval from the moment the control signal is issued until the pressure change curve first deviates from the initial pressure value by more than a preset threshold, where the threshold is the minimum resolvable pressure change of the braking system. It is understood that the pressure change rate and the final stable pressure value are core indicators for evaluating the proportional valve opening adjustment effect and the braking circuit state; these two indicators are directly used for subsequent model comparison analysis. Optionally, after feature extraction and storage, the actual braking pressure change data is sent to the model analysis module via an internal data bus. The sending process is event-triggered to ensure data timeliness. In practical implementation, for the pressure decrease process, the rise time in the above formula... The actual time of descent is the rate of pressure change. A negative value indicates the rate at which the pressure decreases.

[0086] See Figure 3This is a bar chart comparing key characteristics of pressure changes at each wheel of a vehicle's braking system. It's a core visualization result from the "Pressure Change Feature Extraction Stage" of the valve control module, used to quantitatively evaluate the pressure response characteristics of different wheels during braking. This chart can be used to identify differences in braking system response. For example, a longer rise time and initial response time for the right rear wheel may indicate a lag in the proportional valve or a slight resistance anomaly in the brake line, requiring further investigation. By comparing the pressure change rates of each wheel, a quantitative basis can be provided for correcting the proportional valve opening control strategy. For instance, for the low change rate of the right rear wheel, its response efficiency can be improved by adjusting its drive current mapping relationship. If the characteristic value of a particular wheel deviates significantly from that of other wheels, it can serve as an early warning signal for faults such as brake line leakage or proportional valve sticking, assisting the closed-loop monitoring module in achieving proactive compensation.

[0087] In one embodiment of the present invention, referring to Table 1, the model analysis module reads the pressure change rate and final stable pressure value under the current control signal from the actual braking pressure change data. These values ​​are extracted and transmitted by the valve control module in the most recent control cycle. The model analysis module queries the theoretical pressure change rate and theoretical stable pressure value under the same ambient temperature and brake fluid characteristics from the pre-stored pressure-flow-valve opening relationship model. Ambient temperature and brake fluid characteristic parameters are obtained in real time from the thermal management module and the fluid condition monitoring module via the vehicle bus. The model analysis module calculates the deviation between the pressure change rate and the theoretical pressure change rate, and calculates the deviation between the final stable pressure value and the theoretical stable pressure value. The deviation calculation uses absolute difference or percentage difference. It analyzes whether the deviation exceeds the preset allowable range and determines the tendency of the deviation. The determination criteria include the sign, magnitude, and historical trend of the deviation. Possible causes include proportional valve response characteristic drift, brake line leakage, or air in the brake fluid. Specific analysis logic can be found in the deviation analysis mapping relationship shown in Table 1.

[0088] Table 1: Deviation Analysis and Causal Tendency Mapping Relationship:

[0089]

[0090] Based on the comparative analysis results, the model analysis module corrects the proportional valve opening control strategy. If the deviation is within the allowable range, the current opening control strategy is maintained, and only the relevant parameters in the pressure-flow-valve opening relationship model are fine-tuned and updated. If the deviation exceeds the allowable range and is determined to be a drift in the proportional valve response characteristics, the mapping relationship of the pulse width modulation duty cycle or current command value in the proportional valve opening control signal is adjusted in reverse according to the magnitude and direction of the deviation; the correction calculation follows the following formula:

[0091] ;

[0092] in: This represents the corrected control gain coefficient. This represents the default control gain coefficient obtained based on the pre-stored model. Representative based on bias (Pressure change rate deviation) and The compensation amount is calculated based on the deviation of the stable pressure value. If the deviation exceeds the allowable range and a slow leak is identified, a compensation component to maintain the opening is superimposed on the generated control signal. This compensation component is a small, continuous positive current bias or pulse width modulation duty cycle bias to offset the insufficient pressure maintenance caused by the leak. If the deviation exceeds the allowable range and the brake fluid is identified as containing air, a correction strategy is generated that includes a small-amplitude oscillating opening signal at a specific frequency. This oscillating opening signal is a sine or square wave modulated signal superimposed on the original control signal to promote the expulsion of air bubbles. The model analysis module integrates the adjustment and compensation rules adopted for different causes of deviation to form a corrected pulse width modulation duty cycle-target pressure relationship or current-pressure relationship, which serves as the new opening control strategy. This new opening control strategy will override the original strategy and be applied to subsequent control cycles.

[0093] It is understandable that the pre-built pressure-flow-valve opening relationship model is constructed in the hydraulic bench test environment of the vehicle braking system, which can precisely control pressure, flow, and temperature variables. In specific implementation, the target proportional valve is installed in a simulated braking circuit, which includes an adjustable pressure source, a precision flow meter, a temperature control unit, and a data acquisition system. A set of known and precise pulse width modulation duty cycle or current command values ​​covering its operating range are input to the electromagnetic coil of the proportional valve, and the corresponding valve core displacement is recorded as the actual opening. The valve core displacement is measured by a laser displacement sensor or a built-in linear variable differential transformer sensor. At each stable opening, the steady-state flow rate of the brake fluid flowing through the proportional valve at different inlet pressures is measured by the flow meter, generating multiple sets of opening-pressure-flow data points, covering the entire operating pressure and flow range of the proportional valve. Inside the environmental test chamber, the ambient temperature was varied, and different types of brake fluid were used. The following measurement operations were repeated: A set of known and precise pulse width modulation duty cycle or current command values ​​covering the operating range of the proportional valve's solenoid coil were input, and the corresponding valve core displacement was recorded as the actual opening degree. At each stable opening degree, the steady-state flow rate of the brake fluid flowing through the proportional valve under different inlet pressures was measured using a flow meter, generating multiple sets of opening-pressure-flow data points. A set of opening-pressure-flow data points under different temperatures and brake fluid characteristics was obtained. Brake fluid characteristic parameters included viscosity and bulk modulus. Optionally, the range of ambient temperature variation covered extreme low and high temperature conditions that the vehicle might encounter, such as from -40 degrees Celsius to 120 degrees Celsius. Based on the complete set of data points, a mathematical model was established through surface fitting or neural network training. This model took ambient temperature, brake fluid viscosity parameters, and the target pressure change rate as inputs, and the theoretical opening degree or theoretical control current of the proportional valve as outputs. The output of the mathematical model was the predicted control quantity required to achieve the target pressure change rate. In some embodiments, the surface fitting employs the least squares method to perform polynomial surface fitting on the three-dimensional data points, and the neural network training uses a fully connected neural network with hidden layers, with supervised learning using experimental data. The trained and validated mathematical model is stored in the non-volatile memory of the model analysis module, serving as a pressure-flow-valve opening relationship model for online comparison and analysis.

[0094] See Figure 4This is a bar chart comparing pressure deviations in a vehicle braking system, used to quantitatively display the deviation between theoretical calculations and actual measurements. The chart verifies the effectiveness of the "pressure-flow-valve opening relationship model." The quantified deviation results can be directly used to correct model parameters. For example, for minor deviations in the final stable pressure, the mapping relationship between the proportional valve opening and pressure can be fine-tuned to further improve model accuracy. All three types of deviations are at low levels and show a consistent trend, indicating that the braking system has not experienced any abnormalities such as proportional valve drift, pipeline leakage, or brake fluid aeration, and the system is stable. A sudden increase in any type of deviation can serve as a fault warning signal. The quantified deviation data provides a basis for correction in the control generation module. For example, when the pressure change rate deviation exceeds the allowable range, the mapping relationship of the proportional valve drive current can be adjusted in reverse to counteract the effects of system hysteresis or nonlinear characteristics.

[0095] In one embodiment of the invention, the closed-loop monitoring module calculates the slip ratio of each wheel based on the wheel speed signal in real time during the brake pressure following adjustment process. The module compares the slip ratio with the optimal slip ratio range. If the slip ratio of a certain wheel is close to or exceeds a critical value, an anti-lock braking intervention signal is generated for the proportional valve of that wheel. Simultaneously, the module analyzes the yaw rate and lateral acceleration in the vehicle's dynamic parameters. If their deviations from the expected values ​​based on the steering wheel angle are too large, an electronic stability program intervention signal is generated. The anti-lock braking intervention signal or the electronic stability program intervention signal, as a higher priority superimposed instruction, temporarily overrides or modifies the current proportional valve opening control signal. During the period when the intervention signal is in effect, the module continuously monitors the relevant parameters. After the condition is removed, the proportional valve opening control based on the target braking pressure is restored.

[0096] In practical implementation, the closed-loop monitoring module calculates the slip ratio of each wheel in real time based on the wheel speed signal during brake pressure adjustment. The wheel speed signal is provided by the wheel speed sensor in the form of a pulse frequency, and the closed-loop monitoring module converts the pulse period into wheel angular velocity. The closed-loop monitoring module compares the calculated slip ratio with a preset optimal slip ratio range, which is a dynamic upper and lower limit interval adjusted according to road adhesion conditions. If the slip ratio of a certain wheel approaches or exceeds the critical value, the closed-loop monitoring module generates an anti-lock braking intervention signal for the proportional valve of that wheel. The anti-lock braking intervention signal contains an instruction to forcibly reduce the braking pressure. Simultaneously, the closed-loop monitoring module analyzes the yaw rate and lateral acceleration in the vehicle dynamic parameters, which are obtained from the inertial measurement unit. If the measured values ​​of yaw rate and lateral acceleration deviate too much from the expected values ​​based on the steering wheel angle, the closed-loop monitoring module generates an electronic stability program intervention signal. The electronic stability program intervention signal may contain independent brake pressure modulation instructions for one or more wheels. In some embodiments, the condition for determining whether the slip ratio is close to the critical value is the current slip ratio. With the upper limit of the optimal slip ratio Deviation between The calculation method is as follows:

[0097] ;

[0098] when When the value exceeds the preset activation threshold, it is determined to be close to the critical state. It can be understood that the anti-lock braking intervention signal or electronic stabilization program intervention signal, as a higher priority superimposed instruction, temporarily overrides or modifies the current proportional valve opening control signal provided by the control generation module or model analysis module; the signal override is implemented through a priority arbitration logic, whereby the high-priority instruction is directly output to the valve control module, while the update of the low-priority instruction is suspended.

[0099] During the intervention signal's duration, the closed-loop monitoring module continuously monitors relevant parameters, including the wheel slip ratio that triggered the intervention, vehicle yaw rate, and lateral acceleration. Once the condition is resolved, the closed-loop monitoring module resumes proportional valve opening control based on the target braking pressure. The recovery process is gradual; the closed-loop monitoring module withdraws the intervention signal and returns control to the upstream module. The release condition for the anti-lock braking system (ABS) intervention signal is that the slip ratio of the relevant wheel falls back to the optimal slip ratio range and remains there for more than a predetermined duration to avoid control oscillations. The release condition for the electronic stability program (ESC) intervention signal is that the deviations between the measured and expected values ​​of vehicle yaw rate and lateral acceleration return to within the stability margin. Optionally, the pressure modulation strategy employed by the ABS intervention signal is a periodic cycle of pressure increase, holding, and depressurization, with the specific pressure change rate and amplitude dynamically calculated based on the real-time slip ratio deviation. The closed-loop monitoring module dynamically calculates the real-time slip ratio deviation, which is the difference between the wheel slip ratio calculated at the current moment and the median of the preset optimal slip ratio range. Based on the sign and magnitude of the deviation value, the closed-loop monitoring module determines the target pressure change rate and amplitude for each of the three stages—increase, hold, and decrease—in the pressure modulation cycle. During the increase stage, when the real-time slip ratio deviation is negative and has a large absolute value, it indicates that the wheel slip ratio is significantly lower than the optimal value. At this time, the module calculates a large positive pressure change rate and a high target pressure amplitude to rapidly increase the braking pressure. During the hold stage, the closed-loop monitoring module monitors the slip ratio change in real time. If the slip ratio increase rate is too fast and approaches the upper limit of the optimal range, the hold stage is immediately initiated to stabilize the pressure. During the decrease stage, when the real-time slip ratio deviation is positive, it indicates that the wheel slip ratio exceeds the optimal value. The closed-loop monitoring module calculates the required negative pressure change rate and pressure reduction amplitude for the decrease stage based on the magnitude of the deviation value. The larger the deviation value, the faster the calculated decrease rate and the larger the decrease amplitude. The dynamic calculation of the pressure change rate and amplitude relies on a pre-stored slip ratio deviation-pressure modulation parameter mapping table, which defines the benchmark values ​​for the increase rate, decrease rate, and pressure adjustment amplitude corresponding to different deviation intervals. The closed-loop monitoring module reads the real-time slip ratio deviation in each control cycle, queries the mapping table, and performs parameter interpolation and correction by combining the current vehicle speed and the estimated road adhesion coefficient. Finally, it outputs the pressure change rate command and target pressure command for directly driving the proportional valve. The entire calculation process is continuous to ensure that the pressure modulation strategy can follow the changes in slip ratio in real time.

[0100] In practical implementation, temporarily overriding the control signal means that the valve control module only responds to instructions from the closed-loop monitoring module within the current control cycle, ignoring instructions from the control generation module or model analysis module, until the closed-loop monitoring module sends an instruction end flag. It can be understood that the monitoring frequency of the closed-loop monitoring module is much higher than the conventional brake pressure adjustment frequency to ensure rapid perception and response to vehicle instability or wheel lock-up tendencies. Optionally, the desired yaw rate based on the steering wheel angle is calculated using a vehicle reference model, whose inputs include parameters such as steering wheel angle, vehicle speed, and vehicle center of gravity position. When the closed-loop monitoring module generates an electronic stability program intervention signal, it may apply asymmetric corrections to the target braking pressure of different wheels to generate the yaw moment required to correct the vehicle's attitude. During the intervention signal's active period, the closed-loop monitoring module simultaneously alerts the driver that the system is activated, through methods such as illuminating the instrument panel icon or slight steering wheel vibration.

[0101] See Figure 5 This is a bar chart comparing the braking pressure of each wheel before and after ESP intervention, illustrating the mechanism by which the Electronic Stability Program (ESP) corrects vehicle attitude through asymmetric pressure correction. This asymmetric pressure distribution generates a rightward yaw moment in the vehicle, used to correct instability conditions such as oversteer or understeer, returning the vehicle attitude to the desired trajectory matched with the steering wheel angle. The chart visually demonstrates the asymmetric pressure correction mechanism of ESP intervention, verifying the effectiveness of the closed-loop monitoring module in maintaining vehicle dynamic stability by independently modulating the pressure of each wheel. The pressure correction magnitude of each wheel can serve as a quantitative basis for optimizing the pressure modulation strategy of ESP intervention, such as adjusting the correction magnitude to balance the corrective effect and braking comfort. If the pressure correction of a particular wheel does not reach the expected magnitude, it can indicate an abnormality in the proportional valve or brake line of that wheel, assisting in troubleshooting the system.

[0102] The above embodiments are only used to illustrate the technical methods of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical methods of the present invention without departing from the spirit and scope of the technical methods of the present invention.

Claims

1. A vehicle braking control system utilizing a proportional valve, characterized in that, include: The input processing module is used to receive vehicle braking request commands and obtain current vehicle driving status data, and calculate the target braking pressure based on the vehicle braking request commands and the vehicle driving status data. The control generation module is used to generate an initial proportional valve opening control signal based on the difference between the target braking pressure and the current actual braking pressure. The valve control module is used to drive the proportional valve in the braking circuit to adjust the opening degree according to the initial proportional valve opening degree control signal, and to monitor the actual braking pressure change data caused by the opening degree change. The model analysis module is used to compare and analyze the actual braking pressure change data with the pre-stored pressure-flow-valve opening relationship model, and correct the proportional valve opening control strategy based on the comparison and analysis results, so as to update the control signal so that the actual braking pressure follows the target braking pressure change. The closed-loop monitoring module is used to continuously collect wheel speed signals and vehicle dynamic parameters during the brake pressure adjustment process, and to use the signals and parameters to perform closed-loop monitoring and compensation for the brake pressure adjustment process. The step of comparing and analyzing the actual braking pressure change data with the pre-stored pressure-flow-valve opening relationship model specifically includes: Read the pressure change rate and the final stable pressure value under the current control signal from the actual braking pressure change data; From the pre-stored pressure-flow-valve opening relationship model, query the theoretical pressure change rate and theoretical stable pressure value under the same ambient temperature and brake fluid characteristics. Calculate the deviation between the pressure change rate and the theoretical pressure change rate, and calculate the deviation between the final stable pressure value and the theoretical stable pressure value; Analyze whether the deviation exceeds the preset allowable range, and determine the cause of the deviation, such as the proportional valve response characteristics drift, the brake line leakage, or the brake fluid containing air. The proportional valve opening control strategy based on comparative analysis results specifically includes: If the deviation is within the allowable range, the current opening control strategy is maintained, and only the model parameters are fine-tuned and updated. If the deviation exceeds the allowable range and is determined to be a drift in the proportional valve response characteristics, then the mapping relationship of the pulse width modulation duty cycle or current command value in the proportional valve opening control signal is adjusted in reverse according to the magnitude and direction of the deviation. If the deviation exceeds the allowable range and it is determined that there is a slow leak, a compensation component to maintain the opening is superimposed on the generated control signal to counteract the insufficient pressure maintenance caused by the leak. If the deviation exceeds the allowable range and is determined to be due to air in the brake fluid, a correction strategy is generated that includes a small-amplitude oscillation opening signal at a specific frequency to promote the expulsion of air bubbles. The adjustment and compensation rules adopted for different causes of deviation are integrated to form a corrected pulse width modulation duty cycle-target pressure relationship or current-pressure relationship, which serves as the new opening control strategy.

2. The vehicle braking control system using a proportional valve as described in claim 1, characterized in that, The acquisition of current vehicle driving status data specifically includes: Vehicle speed signals, longitudinal acceleration signals, steering wheel angle signals, and yaw rate signals are collected through an onboard sensor network. Read the status flags of the electronic stability program system and the activation status of the anti-lock braking system; Acquire the real-time wheel speed pulse signal of each wheel and calculate the instantaneous slip ratio of each wheel; The vehicle speed signal, longitudinal acceleration signal, steering wheel angle signal, yaw rate signal, status flag, activation status, real-time wheel speed pulse signal, and instantaneous slip ratio value are integrated to form the vehicle driving status data.

3. A vehicle braking control system utilizing a proportional valve for adjustment according to claim 2, characterized in that, The calculation of the target braking pressure based on the vehicle braking request command and the vehicle driving status data specifically includes: The vehicle braking request command is parsed to obtain the braking intensity required by the driver or the deceleration value requested by the advanced driver assistance system. By combining the current vehicle speed and vehicle load information in the vehicle driving status data, a preset braking pressure benchmark mapping table is queried to obtain the basic braking pressure requirement. Based on the steering wheel angle and yaw rate in the vehicle driving status data, the vehicle steering status is determined, and the steering condition is corrected for the basic braking pressure requirement. Based on the activation status of the electronic stability program system or anti-lock braking system in the vehicle driving status data, the additional braking pressure required for dynamic stability control or the pressure modulation component required for anti-lock adjustment is superimposed. By combining the basic braking pressure requirement, the steering condition correction, and the additional braking pressure or pressure modulation component, the target braking pressure finally applied to each wheel is calculated.

4. A vehicle braking control system utilizing a proportional valve as described in claim 3, characterized in that, The step of generating an initial proportional valve opening control signal based on the difference between the target braking pressure and the current actual braking pressure specifically includes: The current actual braking pressure of each brake wheel cylinder is obtained in real time by pressure sensors in the brake line; For each wheel, calculate the pressure difference between the target braking pressure and the current actual braking pressure; Based on the sign and magnitude of the pressure difference, determine the adjustment direction and adjustment intensity reference value of the proportional valve; Based on the preset proportional valve opening-pressure change rate characteristic curve, the adjustment intensity reference value is converted into the corresponding pulse width modulation duty cycle or current command initial value. The pulse width modulation duty cycle or the initial value of the current command is encapsulated into the initial proportional valve opening control signal, which includes the target proportional valve identifier and the corresponding control quantity.

5. A vehicle braking control system utilizing a proportional valve as described in claim 4, characterized in that, The step of driving the proportional valve in the braking circuit to adjust the opening based on the initial proportional valve opening control signal specifically includes: The initial proportional valve opening control signal is sent to the corresponding proportional valve driver; The proportional valve driver outputs a corresponding drive current to the electromagnetic coil of the target proportional valve according to the received control signal. The electromagnetic coil generates electromagnetic force under the action of the driving current, which drives the valve core of the proportional valve to move against the spring preload. The displacement of the valve core changes the flow area of ​​the throttling orifice inside the proportional valve, thereby adjusting the opening degree of the proportional valve. The opening adjustment directly changes the flow resistance of brake fluid from the master cylinder to the wheel cylinder or from the wheel cylinder to the reservoir.

6. A vehicle braking control system utilizing a proportional valve according to claim 5, characterized in that, The monitoring of actual brake pressure changes caused by changes in brake opening specifically includes: After the proportional valve opening adjustment begins, the pressure sensor signal of the brake wheel cylinder is acquired at a frequency higher than the conventional sampling rate. Record the sequence of pressure sensor signals over time to obtain the original curve of pressure rise or fall; The original curve is digitally filtered to remove high-frequency noise interference, resulting in a smooth pressure change curve. Key features are extracted from the smooth pressure change curve, including the initial response time of the pressure change, the rise time to reach the steady value, the rate of pressure change, and the final stable pressure value. The key features are associated with and stored along with the corresponding timestamps, proportional valve identifiers, and initial control signals to form the actual braking pressure change data.

7. A vehicle braking control system utilizing a proportional valve according to claim 6, characterized in that, The closed-loop monitoring and compensation of the braking pressure regulation process using the aforementioned signals and parameters specifically includes: During the brake pressure follow-up adjustment process, the slip ratio of each wheel based on the wheel speed signal is calculated in real time; The slip ratio is compared with the optimal slip ratio range. If the slip ratio of a certain wheel is close to or exceeds the critical value, an anti-lock braking intervention signal is generated for the proportional valve. Simultaneously, the yaw rate and lateral acceleration in the vehicle dynamic parameters are analyzed. If they deviate too much from the expected values ​​based on the steering wheel angle, an electronic stability program intervention signal is generated. The anti-lock braking intervention signal or the electronic stability program intervention signal serves as a higher priority superimposed instruction, temporarily overriding or modifying the current proportional valve opening control signal. During the period when the intervention signal is in effect, relevant parameters are continuously monitored. Once the condition is lifted, proportional valve opening control based on the target braking pressure is restored.

8. A vehicle braking control system utilizing a proportional valve according to claim 7, characterized in that, The method for constructing the pre-stored pressure-flow-valve opening relationship model specifically includes: In the hydraulic bench test environment of the vehicle braking system, the target proportional valve is installed in the simulated braking circuit; Input a set of known and accurate pulse width modulation duty cycle or current command values ​​covering its operating range into the solenoid coil of the proportional valve, and record the corresponding valve core displacement as the actual opening degree. At each stable opening degree, the steady-state flow rate of the brake fluid flowing through the proportional valve under different inlet pressures is measured by a flow meter, generating multiple sets of opening degree-pressure-flow data points; Inside the environmental test chamber, the ambient temperature was changed and different types of brake fluid were used. The following measurement operations were repeated: a set of known and accurate pulse width modulation duty cycle or current command values ​​covering its operating range were input into the solenoid coil of the proportional valve, and the corresponding valve core displacement was recorded as the actual opening degree; at each stable opening degree, the steady-state flow rate of the brake fluid flowing through the proportional valve under different inlet pressures was measured by a flow meter, generating multiple sets of opening degree-pressure-flow rate data points, and obtaining a set of opening degree-pressure-flow rate data points under different temperatures and brake fluid characteristics; Based on the data point set, a mathematical model is established through surface fitting or neural network training, with ambient temperature, brake fluid viscosity parameters, and target pressure change rate as inputs, and the required proportional valve theoretical opening degree or theoretical control current as outputs. The mathematical model is then stored as the pressure-flow-valve opening degree relationship model.

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