Brake-by-wire system and brake monitoring method

Abstract

The invention belongs to the technical field of brake monitoring, and particularly relates to a brake-by-wire system and a brake monitoring method. The drive-by-wire brake system comprises a drive-by-wire pedal, a domain controller, a brake actuator and a wheel speed sensor. According to the invention, dual verification is carried out on the braking force and the wheel speed information through the domain controller, and the deviation between the detection value of the braking force sensor and the calculation value of the domain controller and the deviation between the wheel speed change value and the expected value are calculated. If the deviation is within the preset range, the braking cycle is ended; and if the deviation exceeds the range, a fault alarm prompt signal is sent out. According to the method, sensor faults can be found in time, braking failure is avoided, the safety and reliability of a braking system are improved, and meanwhile the stability and adaptability of the system are considered.

Description

Technical Field

[0001] The present invention belongs to the technical field of brake monitoring, and in particular relates to a brake-by-wire control system and a brake monitoring method. Background Art

[0002] With the continuous development of automobile technology, the wire control brake system has gradually become an important development direction of modern vehicle braking technology. The wire control brake system transmits braking commands through electronic signals. Compared with the traditional mechanical brake system, it has the advantages of fast response speed, high control accuracy, and easy integration with other electronic systems of the vehicle. However, the existing wire control brake system still has some problems in practical application.

[0003] like Figure 1 As shown in the figure, in the existing wire control brake system, the driver's braking intention is converted into an electrical signal through the wire control pedal and transmitted to the domain controller. The domain controller calculates the required braking force according to the preset algorithm and sends the corresponding command to the brake actuator. The brake actuator establishes the braking force according to the command and feeds the braking force data back to the domain controller through the force sensor to realize the control of the braking force.

[0004] This type of brake-by-wire system mainly relies on feedback data from force sensors to monitor braking force. However, the accuracy and stability of force sensors are affected by many factors, such as ambient temperature, humidity, electromagnetic interference, differences in parts manufacturing, and wear and failure of internal parts. When a force sensor fails or data drifts, the domain controller may receive incorrect braking force data, making it unable to accurately determine the braking status of the vehicle, which in turn may cause serious consequences such as vehicle deviation, instability, or even brake failure, affecting the vehicle's driving safety. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a brake-by-wire system and a brake monitoring method, aiming to improve the safety and reliability of the brake-by-wire system without increasing the hardware cost.

[0006] A first aspect of the present invention is to provide a wire control braking system, comprising a wire control pedal, a domain controller, a brake actuator and a wheel speed sensor; the wire control pedal is used to receive a driver's braking request and transmit a braking request signal to the domain controller; the domain controller is used to receive a braking request signal, calculate a required braking force value and send a braking force request to the brake actuator; the brake actuator is used to establish a corresponding braking force according to the received braking force request; the brake actuator includes a force sensor, and the brake actuator feeds back a braking force sensor detection value to the domain controller; the wheel speed sensor is used to monitor the vehicle wheel speed and feed back the wheel speed information to the domain controller; wherein the domain controller synchronously verifies the braking force and wheel speed information, including verifying the deviation between the braking force sensor detection value and the braking force calculation value given by the domain controller, and also includes verifying the deviation between the wheel speed change value in the current braking cycle and the expected wheel speed change calibration value; if the braking force deviation and the wheel speed change deviation are both within the preset range, the current braking cycle is terminated.

[0007] As a further optimization scheme of the wire control brake system of the present invention, let F_request be the required braking force value calculated by the domain controller, F_sensor be the braking force detected by the force sensor in the brake actuator, V_initial be the wheel speed measured by the wheel speed sensor at the beginning of the current braking cycle, V_current be the wheel speed measured by the current wheel speed sensor, ΔV_expected be the calibration value of the expected wheel speed change, ΔV_actual be the actual wheel speed change value, i.e. V_initial - V_current, ε_F be the preset braking force deviation, and ε_V be the preset wheel speed change deviation; If |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual - ΔV_expected| / ΔV_expected ≤ ε_V, then end the current braking cycle; Among them, ε_F is in the range of 3-6%, ε_V is in the range of 5-10%, and ε_F<ε_V.

[0008] As a further optimization scheme of the brake-by-wire system of the present invention, ε_F is 5% and ε_V is 8%.

[0009] As a further optimization scheme of the wire control brake system of the present invention, a method for the domain controller to calculate the required braking force value F_request includes the following steps: receiving a braking request signal from a wire control pedal, the braking request signal including pedal stroke or pedal force information; obtaining the required braking force value F_request based on the pedal stroke or pedal force information in combination with a preset pedal stroke-braking force mapping table or a pedal force-braking force mapping table.

[0010] As a further optimization scheme of the brake-by-wire system of the present invention, if |F_sensor - F_request| / F_request>ε_F or |ΔV_actual - ΔV_expected| / ΔV_expected>ε_V, the domain controller sends a fault alarm prompt signal.

[0011] As a further optimization solution of the brake-by-wire system of the present invention, the process of calibrating ΔV_expected includes the following steps: (1) Perform brake tests at different braking force levels F and different vehicle loads L; (2) In each test, record the initial wheel speed V_initial, real-time wheel speed V_current, and actual braking force F_sensor; (3) Calculate the actual wheel speed change ΔV_actual for each test, where ΔV_actual = V_initial - V_current; (4) Based on the data obtained in steps (2) and (3), establish a mapping function ΔV_expected = func(F, L).

[0012] As a further optimization solution of the wire control brake system of the present invention, the calibrated expected wheel speed change ΔV_expected is expressed as the following linear combination form: ΔV_expected = a⋅F+b⋅L+c; Among them, a, b and c are constants determined by braking test data using a linear regression method.

[0013] A second aspect of the present invention is to provide a braking force monitoring method, which uses the above-mentioned wire control brake system to monitor the braking force of a vehicle.

[0014] The braking force monitoring method comprises the following steps: Step 1: The control-by-wire pedal receives a brake request and transmits a brake request signal to a domain controller; Step 2: After receiving the brake request signal, the domain controller obtains the required brake force value F_request based on the pedal travel or pedal force information and the preset pedal travel-brake force mapping table or pedal force-brake force mapping table, and sends a brake force request to the brake actuator; Step 3: The brake actuator establishes a corresponding braking force according to the received braking force request, and the force sensor in the brake actuator detects the braking force and feeds back the detection value F_sensor to the domain controller; Step 4: The wheel speed sensor monitors the vehicle wheel speed in real time and feeds the wheel speed information back to the domain controller. The domain controller records the wheel speed V_current measured by the current wheel speed sensor and the wheel speed V_initial measured by the wheel speed sensor at the beginning of the current braking cycle, and then calculates the actual wheel speed change value ΔV_actual = V_initial - V_current; Step 5: The domain controller synchronously verifies the braking force and wheel speed information, including: calculating |F_sensor - F_request| / F_request; calculating |ΔV_actual - ΔV_expected| / ΔV_expected; Step 6: Determine whether |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual -ΔV_expected| / ΔV_expected ≤ ε_V, where ε_F is in the range of 3 - 6% and ε_V is in the range of 5 - 10%; Step 7: If both deviations are within the preset range, the current braking cycle ends; if |F_sensor -F_request| / F_request>ε_F or |ΔV_actual - ΔV_expected| / ΔV_expected>ε_V, the domain controller issues a fault alarm prompt signal Beneficial Effects The present invention uses a dual verification mechanism of the braking force and wheel speed information by the domain controller to timely detect the failure of the braking force sensor or the wheel speed sensor, avoid braking failure caused by sensor failure, and improve the safety and reliability of the braking system; at the same time, by setting a reasonable deviation range, the stability and adaptability of the system are taken into account, and false alarms caused by slight errors of the sensor are avoided, thereby ensuring the continuity and reliability of the braking process; in addition, by performing braking tests under different working conditions and establishing a mapping function, the expected wheel speed change value is made closer to reality, further improving the adaptability, safety and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the architecture of a wire control brake system in the prior art.

[0016] Figure 2 FIG. 1 is a schematic diagram of the architecture of the brake-by-wire system of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, but are not intended to be limiting.

[0018] like Figure 2 A wire control brake system is shown, comprising a wire control pedal, a domain controller, a brake actuator and a wheel speed sensor.

[0019] The wire-controlled pedal is used to receive the driver's braking request and transmit the braking request signal to the domain controller; the domain controller is used to receive the braking request signal, calculate the required braking force value and send a braking force request to the brake actuator; the brake actuator is used to establish a corresponding braking force according to the received braking force request; the brake actuator includes a force sensor, and the brake actuator feeds back the braking force sensor detection value to the domain controller; the wheel speed sensor is used to monitor the vehicle wheel speed and feed back the wheel speed information to the domain controller.

[0020] Among them, the domain controller synchronously verifies the braking force and wheel speed information, including verifying the deviation between the braking force sensor detection value and the braking force calculation value given by the domain controller, and also includes verifying the deviation between the wheel speed change value in the current braking cycle and the expected wheel speed change calibration value; if the braking force deviation and the wheel speed change deviation are both within the preset range, the current braking cycle is ended.

[0021] The domain controller double-checks the braking force sensor detection value and calculated value, and the wheel speed change value and expected value. Through this double-check mechanism, the domain controller can monitor the braking force and wheel speed changes at the same time, and use them as references. When the braking force sensor or wheel speed sensor drifts and distorts, the domain controller can detect it in time so that subsequent measures can be taken in time to improve the reliability and safety of the braking system.

[0022] Assume that F_request is the required braking force value calculated by the domain controller, F_sensor is the braking force detected by the force sensor in the brake actuator, V_initial is the wheel speed measured by the wheel speed sensor at the beginning of the current braking cycle, V_current is the wheel speed measured by the current wheel speed sensor, ΔV_expected is the calibration value of the expected wheel speed change, ΔV_actual is the actual wheel speed change value, that is, V_initial - V_current, ε_F is the preset braking force deviation, and ε_V is the preset wheel speed change deviation.

[0023] If |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual - ΔV_expected| / ΔV_expected ≤ ε_V, the current braking cycle is ended.

[0024] Among them, ε_F is in the range of 3-6%, ε_V is in the range of 5-10%, and ε_F<ε_V. The detection of braking force is more direct, and the setting accuracy requirement is higher. The smaller ε_F range (3-6%) ensures the accuracy and stability of braking force monitoring, and avoids poor braking effect or braking failure due to excessive braking force deviation. The wheel speed is affected by the braking force over a longer link, and the accuracy of the change is set lower than that of the braking force. The larger ε_V range (5-10%) can tolerate a certain degree of wheel speed fluctuations, forming appropriate redundancy to adapt to different road conditions and vehicle states, avoiding false alarms due to slight errors in the wheel speed sensor, and ensuring the continuity and reliability of the braking process. This setting enables the domain controller to take into account the stability and adaptability of the system while ensuring the safety and reliability of the braking system.

[0025] More preferably, ε_F is 5% and ε_V is 8%.

[0026] The method for the domain controller to calculate the required braking force value F_request includes the following steps: receiving a braking request signal from a wire-controlled pedal, the braking request signal including pedal stroke or pedal force information; obtaining the required braking force value F_request based on the pedal stroke or pedal force information in combination with a preset pedal stroke-braking force mapping table or a pedal force-braking force mapping table.

[0027] If |F_sensor - F_request| / F_request>ε_F or |ΔV_actual - ΔV_expected| / ΔV_expected>ε_V, the domain controller sends a fault alarm prompt signal.

[0028] Through the above dual verification mechanism of braking force and wheel speed change, the domain controller can promptly detect the failure of the braking force sensor or wheel speed sensor, so as to take follow-up measures in time to avoid brake failure caused by the failure. The fault alarm prompt signal can remind the driver or maintenance personnel to check and repair the braking system in time, thereby improving the safety of the system.

[0029] The process of calibrating ΔV_expected includes the following steps: (1) Perform brake tests at different braking force levels F and different vehicle loads L; (2) In each test, record the initial wheel speed V_initial, real-time wheel speed V_current, and actual braking force F_sensor; (3) Calculate the actual wheel speed change ΔV_actual for each test, where ΔV_actual = V_initial - V_current; (4) Based on the data obtained in steps (2) and (3), establish a mapping function ΔV_expected = func(F, L).

[0030] This process of calibrating ΔV_expected conducts braking tests at different braking force levels and vehicle loads, and establishes a mapping function based on actual data. This can fully cover various operating conditions and make the expected wheel speed change value closer to reality, thereby improving the adaptability, safety and reliability of the system.

[0031] Preferably, the calibrated expected wheel speed change ΔV_expected is expressed as the following linear combination form: ΔV_expected = a⋅F+b⋅L+c.

[0032] Among them, a, b and c are constants determined by braking test data using a linear regression method.

[0033] Expressing ΔV_expected as a⋅F+b⋅L+c is a concise description of the combined effect of braking force F and vehicle load L on the expected wheel speed change through linear combination. Among them, a is a parameter reflecting the rate of change of wheel speed caused by each unit braking force, b is a parameter reflecting the rate of change of wheel speed caused by each unit vehicle load, and c is a bias term, which includes the fixed contribution of other factors (such as vehicle design constants or basic braking characteristics) to ΔV_expected in addition to F and L. The coefficients a, b, and c can be determined based on the measured data through the linear regression method, thereby ensuring that the model is easy to calculate and save computing power under various working conditions while also having high accuracy and reliability.

[0034] Based on the above-mentioned brake-by-wire system, a braking force monitoring method can be executed to monitor the braking force of a vehicle.

[0035] The braking force monitoring method comprises the following steps: Step 1: The control-by-wire pedal receives a brake request and transmits a brake request signal to a domain controller; Step 2: After receiving the brake request signal, the domain controller obtains the required brake force value F_request based on the pedal travel or pedal force information and the preset pedal travel-brake force mapping table or pedal force-brake force mapping table, and sends a brake force request to the brake actuator; Step 3: The brake actuator establishes a corresponding braking force according to the received braking force request, and the force sensor in the brake actuator detects the braking force and feeds back the detection value F_sensor to the domain controller; Step 4: The wheel speed sensor monitors the vehicle wheel speed in real time and feeds the wheel speed information back to the domain controller. The domain controller records the wheel speed V_current measured by the current wheel speed sensor and the wheel speed V_initial measured by the wheel speed sensor at the beginning of the current braking cycle, and then calculates the actual wheel speed change value ΔV_actual = V_initial - V_current; Step 5: The domain controller synchronously verifies the braking force and wheel speed information, including: calculating |F_sensor - F_request| / F_request; calculating |ΔV_actual - ΔV_expected| / ΔV_expected; Step 6: Determine whether |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual -ΔV_expected| / ΔV_expected ≤ ε_V, where ε_F is in the range of 3 - 6% and ε_V is in the range of 5 - 10%; Step 7: If both deviations are within the preset range, the current braking cycle ends; if |F_sensor -F_request| / F_request>ε_F or |ΔV_actual - ΔV_expected| / ΔV_expected>ε_V, the domain controller issues a fault alarm prompt signal.

[0036] The braking force monitoring method can timely detect the fault of the braking force sensor or the wheel speed sensor through the double verification of the braking force and wheel speed information by the domain controller, so as to take follow-up measures in time to avoid braking failure caused by the fault and improve the safety of the system; at the same time, by setting a reasonable deviation range, the stability and adaptability of the system are taken into account, and false alarms caused by slight errors of the sensor are avoided, thereby ensuring the continuity and reliability of the braking process. In addition, by conducting braking tests under different working conditions and establishing a mapping function, the expected wheel speed change value is closer to reality, further improving the adaptability, safety and reliability of the system.

[0037] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and features of the present invention so that people familiar with the technology in this field can understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A brake-by-wire system, characterized in that: It includes a wire-controlled pedal, a domain controller, a brake actuator and a wheel speed sensor; the wire-controlled pedal is used to receive the driver's braking request and transmit the brake request signal to the domain controller; the domain controller is used to receive the brake request signal, calculate the required braking force value and send a braking force request to the brake actuator; the brake actuator is used to establish a corresponding braking force according to the received braking force request; the brake actuator includes a force sensor, and the brake actuator feeds back the braking force sensor detection value to the domain controller; the wheel speed sensor is used to monitor the vehicle wheel speed and feed back the wheel speed information to the domain controller; wherein, the domain controller synchronously verifies the braking force and wheel speed information, including verifying the deviation between the braking force sensor detection value and the braking force calculation value given by the domain controller, and also includes verifying the deviation between the wheel speed change value in the current braking cycle and the expected wheel speed change calibration value; if the braking force deviation and the wheel speed change deviation are both within the preset range, the current braking cycle is terminated.

2. The brake-by-wire system according to claim 1, characterized in that: Let F_request be the required braking force value calculated by the domain controller, F_sensor be the braking force detected by the force sensor in the brake actuator, V_initial be the wheel speed measured by the wheel speed sensor at the beginning of the current braking cycle, V_current be the wheel speed measured by the current wheel speed sensor, ΔV_expected be the calibration value of the expected wheel speed change, ΔV_actual be the actual wheel speed change value, i.e. V_initial - V_current, ε_F be the preset braking force deviation, and ε_V be the preset wheel speed change deviation; If |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual - ΔV_expected| / ΔV_expected ≤ ε_V, then end the current braking cycle; Among them, ε_F is in the range of 3-6% and ε_V is in the range of 5-10%.

3. The brake-by-wire system according to claim 2, characterized in that: ε_F is 5% and ε_V is 8%.

4. The brake-by-wire system according to claim 2, characterized in that: The method for the domain controller to calculate the required braking force value F_request includes the following steps: receiving a braking request signal from a wire-controlled pedal, wherein the braking request signal includes pedal stroke or pedal force information; obtaining the required braking force value F_request based on the pedal stroke or pedal force information in combination with a preset pedal stroke-braking force mapping table or a pedal force-braking force mapping table.

5. The brake-by-wire system according to claim 2, characterized in that: If |F_sensor - F_request| / F_request > ε_F and |ΔV_actual - ΔV_expected| / ΔV_expected > ε_V, the domain controller sends a fault alarm prompt signal.

6. The brake-by-wire system according to claim 2, characterized in that: The process of calibrating ΔV_expected includes the following steps: (1) Perform brake tests at different braking force levels F and different vehicle loads L; (2) In each test, record the initial wheel speed V_initial, real-time wheel speed V_current, and actual braking force F_sensor; (3) Calculate the actual wheel speed change ΔV_actual for each test, where ΔV_actual = V_initial - V_current; (4) Based on the data obtained in steps (2) and (3), establish a mapping function ΔV_expected = func(F,L).

7. The brake-by-wire system according to claim 6, characterized in that: The calibrated expected wheel speed change ΔV_expected is expressed as the following linear combination: ΔV_expected = a⋅F+b⋅L+c; Among them, a, b and c are constants determined by braking test data using linear regression method.

8. A braking force monitoring method, characterized in that: The brake force of a vehicle is monitored using the brake-by-wire system according to any one of claims 1 to 7.

9. The braking force monitoring method according to claim 8, characterized in that: The following steps are involved: Step 1: The control-by-wire pedal receives a brake request and transmits a brake request signal to a domain controller; Step 2: After receiving the brake request signal, the domain controller obtains the required brake force value F_request based on the pedal travel or pedal force information and the preset pedal travel-brake force mapping table or pedal force-brake force mapping table, and sends a brake force request to the brake actuator; Step 3: The brake actuator establishes the corresponding braking force according to the received braking force request, and the force sensor in the brake actuator detects the braking force and feeds back the detection value F_sensor to the domain controller; Step 4: The wheel speed sensor monitors the vehicle wheel speed in real time and feeds the wheel speed information back to the domain controller. The domain controller records the wheel speed V_current measured by the current wheel speed sensor and the wheel speed V_initial measured by the wheel speed sensor at the beginning of the current braking cycle, and then calculates the actual wheel speed change value ΔV_actual = V_initial - V_current; Step 5: The domain controller synchronously verifies the braking force and wheel speed information, including: calculating |F_sensor - F_request| / F_request; calculating |ΔV_actual - ΔV_expected| / ΔV_expected; Step 6: Determine whether |F_sensor - F_request| / F_request ≤ ε_F and |ΔV_actual - ΔV_expected| / ΔV_expected ≤ ε_V, where ε_F is in the range of 3 - 6% and ε_V is in the range of 5 - 10%; Step 7: If both deviations are within the preset range, the current braking cycle ends; if |F_sensor - F_request| / F_request > ε_F or |ΔV_actual - ΔV_expected| / ΔV_expected > ε_V, the domain controller issues a fault alarm prompt signal.

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