Motor vehicle stability control methods, electronic control units and systems

Abstract

The present application discloses a motor vehicle stability control system, an electronic control unit and a method, comprising: during the driving process of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the tire pressure detection values ​​of all wheels of the motor vehicle are determined; according to a pre-prepared library function (F(T)), the determined tire pressure detection values ​​are converted into the static friction force corresponding to each wheel; the static friction forces of each wheel are compared, and when the static friction force of a certain wheel differs from the static friction force of other wheels by more than a predetermined threshold, the wheel is selectively braked.

Description

Technical Field

[0001] The present application generally relates to a control method, an electronic control unit and a system for controlling the body stability of a motor vehicle during driving, especially at high speed, thereby preventing the occurrence of a "wheel hop" phenomenon. Background Art

[0002] At present, the Electronic Stability Program (ESP) module has been widely used in motor vehicles. As an active safety system, it is used to actively provide braking force to the wheels as needed when the motor vehicle understeers or oversteers, or in emergency avoidance, to ensure that the normal trajectory of the motor vehicle is not affected.

[0003] ESP mainly uses various sensors installed on motor vehicles to detect whether the wheels are slipping or lateral slipping during the driving process of the motor vehicle to determine the current condition of the motor vehicle. In order to prevent accidents, it assists the driver in controlling the stability of the vehicle body by braking the wheels accordingly, reducing the engine output power, and other measures.

[0004] When a vehicle is traveling at relatively high speeds, if the driver rapidly and repeatedly turns the steering wheel (for example, to avoid a sudden foreign object on the road while traveling normally at high speed on the highway, the driver turns the wheel first to the left and then suddenly to the right), the vehicle's suspension can suddenly and significantly deform. Centrifugal force can cause the wheel on the inside of the turn (particularly the drive wheel) to jump. This is known as "wheel hop." Wheel hop causes the wheel on the inside of the turn to lift off the ground, resulting in a sudden change in the friction distribution across all four wheels. If the onboard computer does not intervene at this point, the vehicle could even roll over or seriously affect passenger comfort.

[0005] But the ESP system of prior art is seldom equipped with the sensor that detects for the motor vehicle suspension state. In addition, even if configuration, cost also can increase a lot, causes being difficult to promote use on a large scale on common motor vehicle. Summary of the Invention

[0006] In response to the above problems, this application aims to utilize the hardware of the existing ESP system of a motor vehicle to determine "wheel hop" through data analysis of the tire pressure sensor and eliminate this phenomenon accordingly, thereby improving the stability of the motor vehicle during driving.

[0007] According to one aspect of the present application, a method for vehicle stability control executed by an electronic control unit of a vehicle is provided, comprising:

[0008] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives a tire pressure detection value from the tire pressure sensor of the vehicle;

[0009] The electronic control unit converts the received tire pressure detection value into the static friction force corresponding to each wheel according to the pre-prepared library function F(T);

[0010] The electronic control unit compares the static friction forces of the wheels and issues a command to selectively brake a wheel when the static friction force of a wheel differs from that of other wheels by more than a predetermined threshold.

[0011] Optionally, braking of a braked wheel is reduced or stopped as the static friction of that wheel increases.

[0012] Optionally, for each model of motor vehicle, the library function F(T) is obtained by conducting actual road tests in advance and fitting the acquired data.

[0013] Optionally, during the driving of a motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel is rotated in a first direction and then in a second direction opposite to the first direction, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

[0014] Optionally, after the sum of the absolute value of the steering wheel rotation angle in the first direction and the absolute value of the steering wheel rotation angle in the second direction is greater than a predetermined value, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

[0015] Optionally, the predetermined speed value is above 40 km / h.

[0016] According to another aspect of the present application, a method for vehicle stability control executed by an electronic control unit of a vehicle is provided, comprising:

[0017] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives a tire pressure detection value from the tire pressure sensor of the vehicle;

[0018] The electronic control unit compares the tire pressure detection values ​​of each wheel and issues a command to selectively brake the wheel when the tire pressure detection value of a certain wheel differs from the tire pressure detection values ​​of other wheels by more than a predetermined threshold.

[0019] Optionally, when the tire pressure detection value of the braked wheel increases, braking of the wheel is reduced or stopped.

[0020] Optionally, for each model of motor vehicle, the library function F(T) is obtained by conducting actual road tests in advance and fitting the acquired data.

[0021] According to another aspect of the present application, a vehicle stability control system for executing the aforementioned method is proposed, comprising:

[0022] Electronic control units; and

[0023] A tire pressure sensor and a wheel brake electrically connected to the electronic control unit, the electronic control unit being configured to:

[0024] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives tire pressure detection values ​​of all wheels of the motor vehicle from the tire pressure sensors;

[0025] The electronic control unit converts the received tire pressure detection value into the static friction force corresponding to each wheel according to a pre-prepared library function;

[0026] The electronic control unit compares the static friction forces of the wheels and issues a command to the wheel brake to selectively brake the wheel when the static friction force of a wheel differs from that of other wheels by more than a predetermined threshold.

[0027] According to another aspect of the present application, a motor vehicle electronic control unit is provided, wherein the electronic control unit is electrically connected to a tire pressure sensor and a wheel brake, and the electronic control unit is configured to:

[0028] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives tire pressure detection values ​​of all wheels of the motor vehicle from the tire pressure sensors;

[0029] The electronic control unit converts the received tire pressure detection value into the static friction force corresponding to each wheel according to a pre-prepared library function;

[0030] The electronic control unit compares the static friction forces of the wheels and issues a command to the wheel brake to selectively brake the wheel when the static friction force of a wheel differs from that of other wheels by more than a predetermined threshold.

[0031] By employing the above-mentioned technical means of this application, the occurrence of "wheel hop" when repeatedly turning the steering wheel to avoid danger while driving a vehicle at a certain speed can be avoided, thereby ensuring the safety and stability of the vehicle's driving. In addition, the technical solution of this application can be implemented by simply modifying the existing ESP system of a vehicle at a significantly increased cost, thereby reducing the manufacturer's cost of upgrading and modifying the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The following detailed description and the accompanying drawings will provide a more comprehensive understanding of the principles and various aspects of this application. It should be noted that the scales of the various drawings may vary for the purpose of clarity, but this does not affect the understanding of this application. In the accompanying drawings:

[0033] Figure 1 A block diagram of a vehicle stability control system according to an embodiment of the present application is schematically shown;

[0034] Figure 2 A flowchart of a vehicle stability control system method according to an embodiment of the present application is schematically shown; and

[0035] Figure 3a schematically shows a friction circle diagram of a wheel when a motor vehicle is braking while traveling in a straight line; and

[0036] Figure 3b The friction circle diagram (at a certain moment) of the wheels during steering braking of a motor vehicle is schematically shown. DETAILED DESCRIPTION

[0037] In the various figures of this application, features with the same structure or similar functions are indicated by the same reference numerals.

[0038] Figure 1 A schematic diagram illustrates a vehicle stability control system 100 according to one embodiment of the present application. The system includes, for example, an electronic control unit 10 electrically connected to tire pressure sensors 20FL, 20FR, 20RL, and 20RR, respectively, located on the tires of the vehicle's four wheels. The electronic control unit 10, for example, is an onboard computer and includes memory for storing relevant applications and data. Furthermore, the electronic control unit 10 is electrically connected to brakes 30FL, 30FR, 30RL, and 30RR, respectively, located on the vehicle's four wheels. In the above and following descriptions, FL, FR, RL, and RR represent features associated with the left front wheel, right front wheel, left rear wheel, and right rear wheel, respectively.

[0039] It should be clear to those skilled in the art that, although the following description takes a four-wheeled motor vehicle as an example to introduce the technical content of the present application, the same content can be applied to motor vehicles with more or fewer (eg, three) wheels.

[0040] Furthermore, because tire pressure sensors have become standard components of vehicle ESP systems, the vehicle stability control system 100 of the present application can also be directly implemented using existing vehicle ESP systems. This requires only a software upgrade of the ESP system's control program to implement the method embodiments described below, reducing vehicle upgrade and manufacturing costs. In this case, measurements such as vehicle speed, steering wheel angle, and wheel yaw angle can be obtained using sensors in existing ESP systems.

[0041] Next, refer to Figure 2 The following describes the vehicle stability control method according to the present application. This figure merely schematically illustrates an example of the method. It should be noted that the vehicle stability control method according to the present application can be implemented as a subroutine within an ESP control program. Those skilled in the art will appreciate that the method described herein can be executed by the electronic control unit 10.

[0042] like Figure 2 As shown, in step S10, the motor vehicle stability control method (subroutine) according to the present application is entered. Next, in step S20, it is determined whether the speed of the motor vehicle exceeds a predetermined value, for example, whether it is greater than 40 km / h, 50 km / h, 60 km / h or greater. If the judgment result of step S20 is no, then return to step S10; if the judgment result of step S20 is yes, then go to step S30. In step S30, it is determined whether the steering wheel of the motor vehicle is repeatedly turned. If the judgment result of step S30 is no, then go to step S10; if the judgment result of step S30 is yes, then go to step S40. In the context of the present application, "repeatedly turned" means that the steering wheel is turned in one direction and then immediately turned in the opposite direction. When viewed from the outside of the motor vehicle, it means that the wheel turns to one side and then immediately turns to the opposite side.

[0043] The purpose of setting steps S20 and S30 is to prevent the vehicle stability control system of the present application from being activated unnecessarily. In step S40, the tire pressures T of the four wheels of the vehicle are determined. FL 、T FR 、T RL and T RR For example, this can be achieved by the electronic control unit 10 instructing the tire pressure sensors 20FL, 20FR, 20RL and 20RR to obtain tire pressure data. Then, in step S50, based on the tire pressure T FL 、T FR 、T RL and T RR The measured value is used to judge the contact between the wheel and the ground, and then determine the impact of the motor vehicle suspension on the vehicle body stability control.

[0044] For example, a library function F(T) prepared in advance may be stored in the electronic control unit 10 to convert the tire pressure T FL 、T FR 、T RL and T RR The static friction of the corresponding wheel can be obtained by inputting the measured value. It should be clear that when a motor vehicle is driving, if the wheel does not slip, there should only be static friction between the wheel and the ground. The magnitude of this static friction is proportional to the contact area between the motor vehicle tire and the ground. In this way, by using the tire pressure T FL 、T FR 、T RL and T RR The measured value can indirectly determine the static friction of each wheel.

[0045] The library function F(T) can be determined by vehicle or parts manufacturers through extensive measurements simulating actual road conditions before a vehicle leaves the factory. For example, a large number of actual road tests can be conducted on different road surfaces, with different tire sizes, and with vehicles of different weights, and the resulting data can be fitted to obtain the library function F(T). Those skilled in the art will appreciate that this process can be accomplished using big data analysis.

[0046] Next, in step S60, it is determined whether there is a "wheel hop" phenomenon. For example, when a motor vehicle turns right and then suddenly turns left while driving, causing the suspension to tilt significantly, the tire pressure T of the front left wheel is FL The measured value of may increase first and then suddenly decrease significantly - the internal pressure of the wheel decreases due to the loss or imminent loss of contact with the ground, which will cause the static friction of the wheel to decrease or even become zero; the tire pressure of other wheels, such as T FR and T RR The measured value may suddenly increase significantly - this is because the tire is in excessive contact with the ground due to the influence of the suspension, causing the internal pressure to increase, which will cause the static friction of the corresponding wheel to increase. Because when a motor vehicle is turning, if it is driving normally, each wheel is in contact with the ground, resulting in a similar static friction. If monitoring finds that the static friction of a certain wheel decreases abnormally while the static friction of other wheels suddenly increases, it can be determined that "wheel hop" is about to occur or has already occurred. For another example, the tire pressure threshold when the tire is not in contact with the ground can be determined in advance through a large number of tests. If the measured tire pressure value suddenly exceeds the tire pressure threshold, it is determined that "wheel hop" is about to occur or has already occurred on that wheel.

[0047] If the judgment result of step S60 is no, go to step S10; if the judgment result of step S60 is yes, go to step S70.

[0048] In step S70, the static friction of the corresponding wheels when the motor vehicle is turning can be controlled by correspondingly increasing or decreasing the braking force of the corresponding wheels to avoid the "wheel hop" phenomenon.

[0049] In order to explain the measures of the present application to deal with the "round jump" phenomenon, the following first refers to Figure 3a and 3b Explain the static friction experienced by the wheels of a motor vehicle when braking in a straight line and when braking in a corner.

[0050] Figure 3a and Figure 3b All are schematic diagrams of friction circles. Figure 3a Taking a certain wheel of a motor vehicle as an example, the maximum static friction force Fmax experienced when the motor vehicle is braking while traveling in a straight line is shown. Figure 3b The figure shows the situation at a certain moment when a motor vehicle is turning (for example, to the right) and braking. During the driving process of a motor vehicle, if the friction between the wheel and the ground exceeds the maximum static friction, slipping will occur. If the motor vehicle is turning while braking, then the maximum static friction of the wheel can actually be decomposed into a steering force and a braking force that are perpendicular to each other according to the parallelogram law, wherein the steering force is provided by the driver turning the steering wheel, and the braking force is provided by the wheel brakes. Further as shown Figure 3b As shown in the figure, when braking to the right, the maximum static friction force Fmax can be decomposed into a braking force component Fb and a (rightward) steering force component Fs. As the turn progresses, the braking force component Fb gradually decreases and the steering force component Fs gradually increases. Of course, as the turn is completed, the braking force component Fb gradually decreases and the steering force component Fs gradually decreases, and eventually returns to the state shown in the figure. Figure 3a The situation shown.

[0051] From this, it can be seen that in the process of steering and braking the wheel, changing the braking force of the wheel can correspondingly change the static friction of the wheel, thereby changing the braking force to control the stability of the motor vehicle body when "wheel hop" is predicted to occur.

[0052] Going to step S70, for example, the electronic control unit 10 can brake one or more wheels accordingly based on the determined distribution of wheel static friction forces in order to adjust their static friction forces to avoid the occurrence of "wheel hop". The braking rules can be determined based on a large number of actual road tests conducted in advance on different road surfaces, tires of different sizes, and motor vehicles of different weights. Additionally or alternatively, the electronic control unit 10 can actively steer the wheels to change the static friction forces experienced by the wheels and tires. For example, the static friction forces of the wheels are compared, and when the static friction forces of a certain wheel differ from those of the other wheels by more than a predetermined threshold, the wheel is selectively braked.

[0053] In step S70, it can also be configured that if the static friction of the braked wheel increases, the braking of the wheel is correspondingly reduced or stopped. This is because when the "wheel hop" tendency has significantly weakened, reducing or stopping the wheel braking can continue to maintain the turning motion characteristics of the vehicle.

[0054] Furthermore, when a motor vehicle is traveling at high speeds, drivers often turn the steering wheel in one direction and then immediately in the opposite direction to avoid danger. In this situation, the front wheels of the motor vehicle corresponding to the opposite direction are often more likely to experience wheel hop. For example, when a motor vehicle is traveling at high speeds, if the driver first turns the steering wheel left and then right to avoid danger, the right front wheel may often experience wheel hop. To prevent wheel hop, the system can be configured such that, during driving, if the vehicle speed exceeds a predetermined speed value and the steering wheel is rotated in a first direction and then in a second direction opposite to the first direction, selective braking is applied to the front wheels of the motor vehicle corresponding to the second direction. To ensure that front wheel braking is not accidentally triggered, the system can also be configured such that selective braking is applied to the front wheels of the motor vehicle corresponding to the second direction when the sum of the absolute value of the steering wheel rotation angle in the first direction and the absolute value of the steering wheel rotation angle in the second direction exceeds a predetermined value.

[0055] In summary, the present application provides a vehicle stability control method, comprising:

[0056] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the tire pressure detection values ​​of all wheels of the motor vehicle are determined;

[0057] Convert the determined tire pressure detection value into the static friction force corresponding to each wheel according to the pre-prepared library function F(T);

[0058] The static friction forces of the wheels are compared with each other, and when the static friction force of a certain wheel differs from the static friction force of other wheels by more than a predetermined threshold, the wheel is selectively braked.

[0059] As explained above, the above method of the present application can also be implemented based on the results of tire pressure detection. For example, a vehicle stability control method is provided, comprising:

[0060] During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the tire pressure detection values ​​of all wheels of the motor vehicle are determined;

[0061] The tire pressure detection values ​​of each wheel are compared with each other, and when the tire pressure detection value of a certain wheel differs from the tire pressure detection values ​​of other wheels by more than a predetermined threshold, the wheel is selectively braked.

[0062] Although specific embodiments of the present application are described in detail herein, they are provided for illustrative purposes only and should not be construed as limiting the scope of the present application. Furthermore, it will be apparent to those skilled in the art that the various embodiments described herein may be used in combination with one another. Various substitutions, variations, and modifications may be contemplated without departing from the spirit and scope of the present application.

Claims

1. A method for vehicle stability control executed by an electronic control unit of a vehicle, comprising: During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives a tire pressure detection value from the tire pressure sensor of the vehicle; The electronic control unit converts the received tire pressure detection value into the static friction force corresponding to each wheel according to the library function (F(T)) prepared in advance; The electronic control unit compares the static friction forces of each wheel to issue a command to selectively brake the wheel when the static friction force of a wheel differs from that of other wheels by more than a predetermined threshold value. During the driving process of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel is rotated in a first direction and then in a second direction opposite to the first direction, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

2. The method according to claim 1, characterized in that When the static friction of the braked wheel increases, braking of the wheel is reduced or stopped.

3. The method according to claim 1 or 2, characterized in that: For each model of motor vehicle, the library function (F(T)) is obtained by performing actual road tests in advance and fitting the acquired data.

4. The method according to claim 1 or 2, characterized in that: After the sum of the absolute value of the rotation angle of the steering wheel in the first direction and the absolute value of the rotation angle of the steering wheel in the second direction is greater than a predetermined value, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

5. The method according to claim 1 or 2, characterized in that: The predetermined speed value is above 40 km / h.

6. A method for vehicle stability control executed by an electronic control unit of a vehicle, comprising: During the driving of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is repeatedly turned, the electronic control unit receives a tire pressure detection value from the tire pressure sensor of the vehicle; The electronic control unit compares the tire pressure detection values ​​of each wheel to issue a command to selectively brake the wheel when the tire pressure detection value of a certain wheel differs from the tire pressure detection values ​​of other wheels by more than a predetermined threshold value. During the driving process of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel is rotated in a first direction and then in a second direction opposite to the first direction, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

7. The method according to claim 6, characterized in that When the tire pressure detection value of the braked wheel increases, braking of the wheel is reduced or stopped.

8. A vehicle stability control system for executing the method according to any one of claims 1 to 5, comprising: Electronic control unit (10); and A tire pressure sensor (20FL, 20FR, 20RL and 20RR) and a wheel brake (30FL, 30FR, 30RL and 30RR) electrically connected to the electronic control unit (10), wherein the electronic control unit is configured as follows: During the running of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is turned repeatedly, the electronic control unit (10) receives tire pressure detection values ​​of all wheels of the motor vehicle from the tire pressure sensor; The electronic control unit (10) converts the received tire pressure detection value into the static friction force corresponding to each wheel according to a library function (F(T)) prepared in advance; The electronic control unit (10) compares the static friction forces of the wheels to issue a command to the wheel brake to selectively brake the wheel when the static friction force of a wheel differs from the static friction forces of other wheels by more than a predetermined threshold value. During the driving process of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel rotates in a first direction and then in a second direction opposite to the first direction, the front wheel of the motor vehicle corresponding to the second direction is selectively braked.

9. A motor vehicle electronic control unit (10), wherein: The electronic control unit (10) is electrically connected to tire pressure sensors (20FL, 20FR, 20RL and 20RR) and wheel brakes (30FL, 30FR, 30RL and 30RR), and the electronic control unit is configured as follows: During the running of the motor vehicle, if the vehicle speed exceeds a predetermined speed value and the steering wheel of the motor vehicle is turned repeatedly, the electronic control unit (10) receives tire pressure detection values ​​of all wheels of the motor vehicle from the tire pressure sensor; The electronic control unit (10) converts the received tire pressure detection value into the static friction force corresponding to each wheel according to a library function (F(T)) prepared in advance; The electronic control unit (10) compares the static friction forces of the wheels to issue a command to the wheel brake to selectively brake the wheel when the static friction force of a wheel differs from the static friction forces of other wheels by more than a predetermined threshold value, and selectively brakes the front wheels of the motor vehicle corresponding to the second direction if the vehicle speed exceeds a predetermined speed value and the steering wheel rotates in a first direction and then in a second direction opposite to the first direction.

10. The electronic control unit (10) according to claim 9, characterized in that When the static friction of the braked wheel increases, braking of the wheel is reduced or stopped.

11. The electronic control unit (10) according to claim 9 or 10, characterized in that: For each model of motor vehicle, the library function (F(T)) is obtained by performing actual road tests in advance and fitting the acquired data.

12. The electronic control unit (10) according to claim 11, characterized in that After the sum of the absolute value of the rotation angle of the steering wheel in the first direction and the absolute value of the rotation angle of the steering wheel in the second direction is greater than a predetermined value, the front wheels of the motor vehicle corresponding to the second direction are selectively braked.

13. The electronic control unit (10) according to claim 9 or 10, characterized in that: The predetermined speed value is above 40 km / h.

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