EPB anti-lock control method and system based on composite tire pressure monitoring

Abstract

The invention discloses an EPB anti-lock control method and system based on composite tire pressure monitoring, and belongs to the field of automobile braking, and the method comprises the following steps: S1, collecting a wheel speed signal, an acceleration signal, a tire pressure signal, a driving slope angle signal and a temperature signal of each wheel in real time; s2, whether emergency braking is started or not is judged through an indirect tire pressure monitoring method and a direct tire pressure monitoring method, if yes, the step S3 is executed, and if not, the step S1 is returned; s3, calculating the initial holding force of the wheel; s4, initial holding force is applied; s5, dynamic braking adjustment is conducted, specifically, the slip rate is calculated based on the dynamically compensated tire radius, and the holding force of a left brake caliper and the holding force of a right brake caliper are dynamically adjusted based on the slip rate; and S6, braking is finished. By the adoption of the EPB anti-lock control method and system based on combined type tire pressure monitoring, the safety and reliability of vehicle braking and parking are remarkably improved through data sharing and cooperative control.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive braking, and particularly to an EPB anti-lock control method and system based on compound tire pressure monitoring. Background Art

[0002] As an upgraded solution to the traditional mechanical handbrake, the electronic parking brake system (EPB) has become a key component of modern automotive braking systems due to its convenience and intelligence advantages. In the early stage, EPB mainly relied on fixed clamping force control, and its function was similar to that of a mechanical handbrake, only providing auxiliary braking through the rear wheel calipers during emergency braking. Therefore, the improvement in safety performance was limited. With the progress of active safety technologies, the EPB anti-lock system adjusts the rear wheel braking force through wheel speed signals, but has not fully integrated multi-source information such as tire pressure monitoring. In the case of underinflated tires, its adaptability to complex road conditions (such as slippery roads and oncoming roads) is still insufficient.

[0003] In the above context, as a key factor affecting the safety performance of automobiles, the status monitoring of tires is particularly important. The indirect tire pressure monitoring system and the direct tire pressure monitoring system are currently the two most commonly used tire pressure monitoring solutions. The indirect tire pressure monitoring system can only judge whether the tire pressure is abnormal and cannot accurately display the specific pressure value of each tire; and due to factors such as differences in road conditions and uneven tire wear, false alarms are likely to occur; when the air pressure abnormality is detected, its reaction speed is slow and cannot meet the fast response requirements of EPB anti-lock control. The direct tire pressure monitoring system can make up for the deficiencies of the indirect tire pressure monitoring system in these aspects, but the service life of its sensor battery is limited and it is easily affected by signal interference, resulting in inaccurate tire pressure values reported. Summary of the Invention

[0004] The purpose of the present invention is to provide an EPB anti-lock control method and system based on compound tire pressure monitoring to solve the above technical problems.

[0005] To achieve the above purpose, the present invention provides an EPB anti-lock control method based on compound tire pressure monitoring, including the following steps: S1. Real-time collect the wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal, and temperature signal of each wheel; S2. Calculate the tire radius of the wheel using the indirect tire pressure monitoring method based on the wheel speed signal, and dynamically compensate the tire radius using the direct tire pressure monitoring method based on the tire pressure signal and temperature signal. Then calculate the tire pressure deviation ratio based on the compensated tire radius, and judge whether to start emergency braking. If so, execute step S3; otherwise, return to step S1; S3. Calculate the initial clamping force of the wheel based on the dynamically compensated tire radius; S4. Initial Braking: The left brake caliper and the right brake caliper apply initial clamping forces to the left rear wheel and the right rear wheel respectively; S5. Dynamic Braking Adjustment: Calculate the slip ratio based on the dynamically compensated tire radius, and dynamically adjust the clamping forces of the left brake caliper and the right brake caliper based on the slip ratio to avoid locking; S6. Braking End: When the detected vehicle speed is lower than the set vehicle speed, the deceleration stops, or the slip ratio of the set wheel is reached, stop braking.

[0006] Preferably, step S2 specifically includes the following steps: S21. Calculate the vehicle speed based on the wheel speed signal: (1); Wherein, , , , respectively represent the wheel speeds of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel of the vehicle; S22. Calculate the tire radius: (2); Wherein, , , , respectively represent the tire radii of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel; , , , respectively represent the angular velocities of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel; S23. Dynamically compensate the tire radius using the direct tire pressure monitoring method: (3); (4); (5); (6); Wherein, , , , respectively represent the dynamically compensated tire radii of the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel; represents the tire pressure influence coefficient; and respectively represent the current tire pressure and the standard tire pressure; and respectively represent the current temperature and the standard temperature; represents the elastic modulus coefficient; S24. Calculate the tire pressure deviation ratio : (7); S25. Determine whether to activate emergency braking: When the tire pressure deviation ratio is reached, activate emergency braking.

[0007] Preferably, the initial clamping force described in step S3 includes the clamping forces of the left caliper and the right caliper, and its calculation formula is as follows: (8); (9); In the formula, and respectively represent the clamping forces of the left caliper and the right caliper; represents the vehicle mass; represents the gravitational acceleration; represents the driving slope angle; represents the friction coefficient between the wheel and the ground; represents the effective radius of the brake caliper.

[0008] Preferably, step S5 specifically includes the following steps: S51. Calculate the slip ratio: (10); (11); (12); (13); In the formula, , , , respectively represent the slip ratios of the left front wheel, right front wheel, left rear wheel and right rear wheel; S52. Dynamically adjust the clamping force based on the slip ratio: If is greater than the preset locked slip ratio for a time of , and the clamping force is , then release the left brake caliper until the clamping force is 0; if is less than the preset locked slip ratio for a time of , then continue to clamp the left brake caliper, and the clamping step size is , and alternately execute the clamping and releasing operations at intervals of ; If is greater than the preset locked slip ratio for a time of , and the clamping force is , the right brake caliper is released until the clamping force is 0; if the time less than the preset anti-lock slip ratio is , the right brake caliper continues to be clamped, and the clamping step is , and the clamping and releasing operations are alternately executed at the time interval of .

[0009] Preferably, in step S6, it is judged whether to stop decelerating according to the instantaneous deceleration : (14); In the formula, represents the change value of the front wheel speed of the vehicle; represents the time taken for the change of the front wheel speed of the vehicle.

[0010] A system for implementing an EPB anti-lock control method based on compound tire pressure monitoring includes a data acquisition module, an EPB controller, a left brake caliper and a right brake caliper. Among them, the data acquisition module is used to collect the wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal and temperature signal of each wheel in real time. The EPB controller is used to calculate the initial clamping force and dynamically adjust the clamping force based on the collected wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal and temperature signal; the left brake caliper and the right brake caliper are respectively used to apply the initial clamping force and the dynamically adjusted clamping force to the left rear wheel and the right rear wheel.

[0011] Preferably, the data acquisition module includes a wheel speed sensor, an acceleration sensor, a tire pressure sensor and a temperature sensor integrated on each wheel, and a slope sensor integrated on the vehicle. Among them, the wheel speed sensor, acceleration sensor, tire pressure sensor and temperature sensor are respectively used to collect the wheel speed signal, acceleration signal, tire pressure signal and temperature signal of the corresponding wheel, and the slope sensor is used to collect the driving slope angle signal.

[0012] Therefore, the present invention adopts the above-mentioned EPB anti-lock control method and system based on compound tire pressure monitoring, and has the following beneficial effects: 1. Improve braking and parking safety: By using compound tire pressure monitoring to collect tire pressure and temperature data in real time, and combining with the wheel speed sensor to analyze the wheel speed difference, tire abnormalities can be detected in time; when detecting abnormal reduction of tire pressure or abnormal increase of wheel speed (change of tire radius), the system accurately controls the braking force to ensure that the vehicle decelerates smoothly until it stops, avoiding vehicle out of control and enhancing the driving safety factor (for example, when the tire suddenly leaks, the system can quickly respond and adjust the clamping force of the rear wheel caliper to prevent the vehicle from skidding); 2. Optimize the collaborative efficiency of multiple systems: The compound tire pressure monitoring and EPB system share data and cooperate in control, solving the problems of insufficient safety of traditional EPB emergency braking and low collaborative efficiency of multiple systems. The direct and indirect tire pressure monitoring modules complement each other, improving the accuracy of tire status monitoring, providing reliable data for the EPB system, and making the braking control more precise and efficient. 3. Meet the development needs of intelligent driving: Meet the requirements of high precision and fast response of the braking system for autonomous driving, and provide an innovative path for the upgrade of the braking system in the era of intelligent driving.

[0013] In summary, through the collaborative analysis of tire pressure data and wheel speed signals, the present invention can effectively cope with complex working conditions such as low-adhesion road surfaces and oncoming road surfaces of vehicles, meet the requirements of high precision and fast response of the braking system for autonomous driving. Moreover, it solves the problems of insufficient safety of traditional EPB emergency braking and low collaborative efficiency of multiple systems, providing an innovative path for the upgrade of the braking system in the era of intelligent driving.

[0014] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0015] Figure 1 It is a flowchart of an EPB anti-lock control method based on compound tire pressure monitoring of the present invention. Detailed Embodiments

[0016] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of this application. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end.

[0017] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or server that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0018] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] As Figure 1As shown in the figure, an EPB anti-lock control method based on compound tire pressure monitoring includes the following steps: S1. Real-time collect the wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal, and temperature signal of each wheel; S2. Calculate the tire radius of the wheel using the indirect tire pressure monitoring method based on the wheel speed signal, and dynamically compensate the tire radius using the direct tire pressure monitoring method based on the tire pressure signal and temperature signal. Then, calculate the tire pressure deviation ratio based on the compensated tire radius, and determine whether to activate the emergency brake. If so, execute step S3; otherwise, return to step S1; Step S2 specifically includes the following steps: S21. Calculate the vehicle speed based on the wheel speed signal: (1); In the formula, , , , respectively represent the wheel speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel of the vehicle; S22. Calculate the tire radius: (2); In the formula, , , , respectively represent the tire radii of the left front wheel, right front wheel, left rear wheel, and right rear wheel; , , , respectively represent the angular velocities of the left front wheel, right front wheel, left rear wheel, and right rear wheel; S23. Dynamically compensate the tire radius using the direct tire pressure monitoring method: (3); (4); (5); (6); In the formula, , , , respectively represent the tire radii of the left front wheel, right front wheel, left rear wheel, and right rear wheel after dynamic compensation; represents the tire pressure influence coefficient; and respectively represent the current tire pressure and the standard tire pressure; and respectively represent the current temperature and the standard temperature; Denote the elastic modulus coefficient; S24. Calculate the tire pressure deviation ratio : (7); S25. Determine whether to activate emergency braking: When the tire pressure deviation ratio is reached, activate emergency braking.

[0020] S3. Calculate the initial clamping force of the wheel based on the dynamically compensated tire radius; The initial clamping force described in step S3 includes the clamping forces of the left caliper and the right caliper, and its calculation formula is as follows: (8); (9); In the formula, and respectively represent the clamping forces of the left caliper and the right caliper; Denotes the vehicle mass; Denotes the acceleration due to gravity; Denotes the driving slope angle; Denotes the friction coefficient between the wheel and the ground; Denotes the effective radius of the brake caliper.

[0021] S4. Preliminary braking: The left brake caliper and the right brake caliper apply the initial clamping force to the left rear wheel and the right rear wheel respectively; S5. Dynamic braking adjustment: Calculate the slip ratio (which represents the proportion of the wheel's sliding in the vehicle's driving) based on the dynamically compensated tire radius, and dynamically adjust the clamping forces of the left brake caliper and the right brake caliper based on the slip ratio to avoid locking; Step S5 specifically includes the following steps: S51. Calculate the slip ratio: (10); (11); (12); (13); In the formula, , , , respectively represent the slip ratios of the left front wheel, the right front wheel, the left rear wheel and the right rear wheel; S52. Dynamically adjust the clamping force based on the slip ratio: If is greater than the preset lock-up slip ratio for a time of , the clamping force is , release the left brake caliper until the clamping force is 0; if the time less than the preset locked slip ratio is , continue to clamp the left brake caliper, and the clamping step is , and perform the clamping and releasing operations alternately at the time interval of ; If the time greater than the preset locked slip ratio is , and the clamping force is , release the right brake caliper until the clamping force is 0; if the time less than the preset locked slip ratio is , continue to clamp the right brake caliper, and the clamping step is , and perform the clamping and releasing operations alternately at the time interval of .

[0022] S6. Braking end: When it is detected that the vehicle speed is lower than the set vehicle speed, the deceleration stops, or the slip ratio of the set wheel is reached, the braking stops.

[0023] In step S6, it is judged whether to stop decelerating according to the instantaneous deceleration : (14); In the formula, represents the change value of the front wheel speed of the vehicle; represents the time taken for the change of the front wheel speed of the vehicle.

[0024] A system for implementing the EPB anti-lock control method based on compound tire pressure monitoring includes a data acquisition module, an EPB controller, a left brake caliper, and a right brake caliper. Among them, the data acquisition module is used to collect the wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal, and temperature signal of each wheel in real time. The EPB controller is used to calculate the initial clamping force and dynamically adjust the clamping force based on the collected wheel speed signal, acceleration signal, tire pressure signal, driving slope angle signal, and temperature signal; the left brake caliper and the right brake caliper are respectively used to apply the initial clamping force and the dynamically adjusted clamping force to the left rear wheel and the right rear wheel.

[0025] Specifically, the data acquisition module includes a wheel speed sensor, an acceleration sensor, a tire pressure sensor, and a temperature sensor integrated on each wheel, and a slope sensor integrated on the vehicle. Among them, the wheel speed sensor, acceleration sensor, tire pressure sensor, and temperature sensor are respectively used to collect the wheel speed signal, acceleration signal, tire pressure signal, and temperature signal of the corresponding wheel, and the slope sensor is used to collect the driving slope angle signal.

[0026] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements do not cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An EPB anti-lock control method based on compound tire pressure monitoring, characterized in that: It includes the following steps: S1. Real-time collect the wheel speed signal, acceleration signal, tire pressure signal, driving gradient angle signal and temperature signal of each wheel; S2. Based on the wheel speed signal, use the indirect tire pressure monitoring method to calculate the tire radius of the wheel, and based on the tire pressure signal and temperature signal, use the direct tire pressure monitoring method to dynamically compensate the tire radius. Then, based on the compensated tire radius, calculate the tire pressure deviation ratio and determine whether to activate the emergency brake. If so, execute step S3; otherwise, return to step S1; S3. Calculate the initial clamping force of the wheel based on the dynamically compensated tire radius; S4. Preliminary braking: The left brake caliper and the right brake caliper respectively apply the initial clamping force to the left rear wheel and the right rear wheel; S5. Dynamic braking adjustment: Calculate the slip ratio based on the dynamically compensated tire radius, and dynamically adjust the clamping forces of the left brake caliper and the right brake caliper based on the slip ratio to avoid locking; S6. Braking end: When it is detected that the vehicle speed is lower than the set vehicle speed, the deceleration stops or the slip ratio of the set wheel is reached, stop braking.

2. The EPB anti-lock control method based on compound tire pressure monitoring according to claim 1, wherein: Step S2 specifically includes the following steps: S21. Calculate the vehicle speed based on the wheel speed signal: （1）； In the formula, , , , respectively represent the wheel speeds of the left front wheel, right front wheel, left rear wheel and right rear wheel of the vehicle; S22. Calculate the tire radius: （2）； In the formula, , , , respectively represent the tire radii of the left front wheel, right front wheel, left rear wheel, and right rear wheel; , , , respectively represent the angular velocities of the left front wheel, right front wheel, left rear wheel, and right rear wheel; S23. Dynamically compensate the tire radius using the direct tire pressure monitoring method: （3）； （4）； （5）； （6）； Wherein, , , , respectively represent the tire radii of the left front wheel, right front wheel, left rear wheel, and right rear wheel after dynamic replenishment; represents the tire pressure influence coefficient; and respectively represent the current tire pressure and the standard tire pressure; and respectively represent the current temperature and the standard temperature; represents the elastic modulus coefficient; S24. Calculate the tire pressure deviation ratio : （7）； S25. Determine whether to activate emergency braking: When the tire pressure deviation ratio is reached, activate emergency braking.

3. The EPB anti-lock control method based on compound tire pressure monitoring according to claim 2, wherein: The initial clamping force described in step S3 includes the clamping forces of the left caliper and the right caliper, and its calculation formula is as follows: （8）； （9）； In the formula, and respectively represent the clamping forces of the left caliper and the right caliper; represents the vehicle mass; represents the acceleration due to gravity; represents the driving slope angle; represents the friction coefficient between the wheel and the ground; represents the effective radius of the brake caliper.

4. The EPB anti-lock control method based on compound tire pressure monitoring according to claim 3, wherein: Step S5 specifically includes the following steps: S51. Calculate the slip ratio: （10）； （11）； （12）； （13）； In the formula, , , , respectively represent the slip ratios of the left front wheel, right front wheel, left rear wheel and right rear wheel; S52. Dynamically adjust the clamping force based on the slip ratio: If the time greater than the preset locking slip ratio is and the clamping force is , release the left brake caliper until the clamping force is 0; If the time less than the preset locking slip ratio is , continue to clamp the left brake caliper, and the clamping step is . Alternately execute the clamping and releasing operations at the time interval of . If the time greater than the preset locking slip ratio is and the clamping force is , release the right brake caliper until the clamping force is 0; if the time less than the preset locking slip ratio is , continue to clamp the right brake caliper, and the clamping step is . Execute the clamping and releasing operations alternately at the time interval of .

5. The EPB anti-lock control method based on compound tire pressure monitoring according to claim 4, characterized in that: In step S6, based on the instantaneous deceleration judge whether to stop decelerating: （14）； Wherein, represents the change value of the front wheel speed of the vehicle; represents the time taken for the change of the front wheel speed of the vehicle.

6. A system for implementing the EPB anti-lock control method based on compound tire pressure monitoring according to claim 5 above, characterized in that: It includes a data acquisition module, an EPB controller, a left brake caliper and a right brake caliper. Among them, the data acquisition module is used to real-time collect the wheel speed signal, acceleration signal, tire pressure signal, driving gradient angle signal and temperature signal of each wheel. The EPB controller is used to calculate the initial clamping force and dynamically adjust the clamping force based on the technically collected wheel speed signal, acceleration signal, tire pressure signal, driving gradient angle signal and temperature signal; the left brake caliper and the right brake caliper are respectively used to apply the initial clamping force and the dynamically adjusted clamping force to the left rear wheel and the right rear wheel.

7. The system of the EPB anti-lock control method based on compound tire pressure monitoring according to claim 6, characterized in that: The data acquisition module includes a wheel speed sensor, an acceleration sensor, a tire pressure sensor and a temperature sensor integrated on each wheel, and a gradient sensor integrated on the vehicle. Among them, the wheel speed sensor, the acceleration sensor, the tire pressure sensor and the temperature sensor are respectively used to collect the wheel speed signal, acceleration signal, tire pressure signal and temperature signal of the corresponding wheel, and the gradient sensor is used to collect the driving gradient angle signal.

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