Vehicle rear-wheel steering control method, apparatus and system, and vehicle

Abstract

A vehicle rear-wheel steering control method and apparatus, which are provided in a vehicle having a steering control system. The method comprises: acquiring an average wheel steering angle of a vehicle; on the basis of the average wheel steering angle and a preset mapping relationship, determining the steering angle difference between left and right rear wheels, wherein the preset mapping relationship is a mapping relationship designed to make an Ackermann percentage reach a preset threshold value; on the basis of the average wheel steering angle and the steering angle difference between the left and right rear wheels, determining respective steering angles of the left and right rear wheels; and on the basis of the respective steering angles of the left and right rear wheels, controlling the left rear wheel and the right rear wheel of the vehicle.

Description

Rear-wheel steering control methods, devices, systems and vehicles

[0001] This application claims priority to Chinese Patent Application No. 202410705382.1, filed on May 31, 2024, entitled "Rear Wheel Steering Control Method, Apparatus, System and Vehicle", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to, but is not limited to, the field of vehicle control technology, specifically to a method, device, system, and vehicle for controlling the rear wheel steering of a vehicle. Background Technology

[0003] As people's requirements for vehicle handling stability and safety have become increasingly higher, the shortcomings of front-wheel steering vehicles, such as poor low-speed steering flexibility and low high-speed steering stability, have led researchers to begin researching new steering technologies. Based on this, four-wheel steering technology, namely front-wheel steering + rear-wheel steering, was born.

[0004] Currently, the steering performance of rear-wheel steering control schemes is quite limited. Technical solutions

[0005] According to one aspect of this application, a method for controlling the rear wheel steering of a vehicle is provided. The method includes: acquiring the average wheel angle of the vehicle; determining the angle difference between the left and right rear wheels based on the average wheel angle and a preset mapping relationship, wherein the preset mapping relationship is a mapping relationship designed to make the Ackerman ratio reach a preset threshold; determining the respective steering angle of the left and right rear wheels based on the average wheel angle and the angle difference between the left and right rear wheels; and controlling the left and right rear wheels of the vehicle based on the respective steering angles of the left and right rear wheels.

[0006] In an embodiment of this application, obtaining the average wheel angle of the vehicle includes: obtaining a steering wheel angle signal; obtaining the average angle of the left and right front wheels based on the steering wheel angle signal; and obtaining the average angle of the left and right rear wheels based on the average angle of the left and right front wheels.

[0007] In an embodiment of this application, determining the angle difference between the left and right rear wheels based on the average turning angle of the wheels and a preset mapping relationship includes: obtaining the actual turning angle of the inner front wheel used for turning based on the average turning angle of the left and right front wheels; obtaining the ideal turning angle of the inner front wheel when the Ackerman ratio reaches 100% based on the actual turning angle of the inner front wheel; and obtaining the angle difference between the left and right rear wheels based on the ideal turning angle of the inner front wheel and a first preset mapping relationship, wherein the first preset mapping relationship is a preset mapping relationship between the ideal turning angle of the inner front wheel and the angle difference between the left and right rear wheels.

[0008] In an embodiment of this application, determining the angle difference between the left and right rear wheels based on the average turning angle of the wheels and a preset mapping relationship includes: obtaining the actual turning angle of the outer front wheel used for turning based on the average turning angle of the left and right front wheels; obtaining the ideal turning angle of the outer front wheel when the Ackerman ratio reaches 100% based on the actual turning angle of the outer front wheel; and obtaining the angle difference between the left and right rear wheels based on the ideal turning angle of the outer front wheel and a second preset mapping relationship, wherein the second preset mapping relationship is a preset mapping relationship between the ideal turning angle of the outer front wheel and the angle difference between the left and right rear wheels.

[0009] In an embodiment of this application, obtaining the average turning angle of the left and right rear wheels based on the average turning angle of the left and right front wheels includes: obtaining the vehicle speed; obtaining a proportionality coefficient between the average turning angle of the left and right rear wheels and the average turning angle of the left and right front wheels based on a preset function, wherein the independent variable of the preset function is the vehicle speed and the dependent variable of the preset function is the proportionality coefficient; and multiplying the average turning angle of the left and right front wheels by the proportionality coefficient to obtain the average turning angle of the left and right rear wheels.

[0010] In embodiments of this application, in response to the vehicle speed being less than a preset vehicle speed, the proportional coefficient is negative, and the turning directions of the left and right rear wheels are opposite to the turning directions of the left and right front wheels; in response to the vehicle speed being not less than the preset vehicle speed, the proportional coefficient is positive, and the turning directions of the left and right rear wheels are in the same direction as the turning directions of the left and right front wheels.

[0011] In an embodiment of this application, determining the respective turning angles of the left and right rear wheels based on the average turning angle of the wheel and the difference in turning angles between the left and right rear wheels includes: multiplying the difference in turning angles between the left and right rear wheels by a preset coefficient to obtain a turning angle offset, wherein the preset coefficient is greater than 0 and less than 1; adding the turning angle offset to the average turning angle of the left and right rear wheels to obtain the turning angle of the inner rear wheel; and subtracting the turning angle offset from the average turning angle of the left and right rear wheels to obtain the turning angle of the outer rear wheel.

[0012] According to another aspect of this application, a vehicle rear-wheel steering control device is provided, the control device including a memory and a processor, wherein the memory stores a computer-executable program executed by the processor, the computer-executable program, when executed by the processor, causes the processor to perform the above-described vehicle rear-wheel steering control method.

[0013] According to another aspect of this application, a vehicle rear-wheel steering control system is provided. The control system includes a sensor, a left rear-wheel steering gear, a right rear-wheel steering gear, and the aforementioned vehicle rear-wheel steering control device, wherein: the vehicle rear-wheel steering control device is used to obtain the average wheel angle of the vehicle from the sensor, determine the respective steering angles of the left and right rear wheels based on the average wheel angle, generate a left rear wheel steering angle signal and a right rear wheel steering angle signal, and send the left rear wheel steering angle signal and the right rear wheel steering angle signal to the left rear wheel steering gear and the right rear wheel steering gear, respectively; the left rear wheel steering gear is used to control the left rear wheel based on the left rear wheel steering angle signal; and the right rear wheel steering gear is used to control the right rear wheel based on the right rear wheel steering angle signal.

[0014] According to another aspect of this application, a vehicle is provided, the vehicle including the above-described vehicle rear wheel steering control device or the above-described vehicle rear wheel steering control system.

[0015] According to another aspect of this application, a storage medium is provided that stores a computer program executed by a processor, which, when executed by the processor, causes the processor to perform the aforementioned vehicle rear wheel steering control method.

[0016] According to another aspect of this application, a computer program is provided that, when run by a processor, causes the processor to perform the above-described vehicle rear wheel steering control method.

[0017] The vehicle rear-wheel steering control method, device, system, and vehicle of this application, through reasonable control strategies to adjust the rear wheel steering angle, can achieve better steering performance than other rear-wheel steering methods, improve the steering limit grip, reduce tire wear, and reduce the probability of tire low-temperature abnormal noise. Attached Figure Description

[0018] The above and other objects, features, and advantages of this application will become more apparent from the more detailed description of the embodiments of this application in conjunction with the accompanying drawings. The drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the embodiments of this application to explain this application and do not constitute a limitation thereof. In the drawings, the same reference numerals generally represent the same components or steps.

[0019] Figure 1 shows a schematic flowchart of a vehicle rear wheel steering control method according to an embodiment of this application.

[0020] Figure 2 shows a schematic diagram of a vehicle with ideal Arman steering when there is no rear wheel steering.

[0021] Figure 3 shows a schematic diagram of a vehicle with non-ideal Arman steering when there is no rear wheel steering.

[0022] Figure 4 shows a schematic diagram of an example vehicle achieving ideal Alman rate steering based on the vehicle rear wheel steering control method according to an embodiment of this application.

[0023] Figure 5 shows a vehicle schematic diagram of another example of achieving ideal Arman rate steering based on the vehicle rear wheel steering control method according to an embodiment of this application.

[0024] Figure 6 shows a schematic structural block diagram of a vehicle rear wheel steering control device according to an embodiment of this application.

[0025] Figure 7 shows a schematic structural block diagram of a vehicle rear wheel steering control system according to an embodiment of this application.

[0026] Figure 8 shows a schematic operation flowchart of a vehicle rear wheel steering control system according to an embodiment of this application.

[0027] Implementation methods of this application

[0028] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of this application, and not all of the embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0029] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of this application, and not all of the embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0030] Figure 1 shows a schematic flowchart of a vehicle rear-wheel steering control method 100 according to an embodiment of the present application. As shown in Figure 1, the vehicle rear-wheel steering control method 100 according to an embodiment of the present application may include the following steps:

[0031] In step S110, the average wheel angle of the vehicle is obtained.

[0032] In step S120, the angle difference between the left and right rear wheels is determined based on the average wheel angle and a preset mapping relationship, wherein the preset mapping relationship is a mapping relationship designed to make the Ackerman ratio reach a preset threshold.

[0033] In step S130, the turning angles of the left and right rear wheels are determined based on the average turning angle of the wheels and the difference in turning angles between the left and right rear wheels.

[0034] In step S140, the left and right rear wheels of the vehicle are controlled based on the respective turning angles of the left and right rear wheels.

[0035] In embodiments of this application, a control method is provided for separately controlling the left and right rear wheels when a vehicle is turning, including a method for calculating the required turning angles for each of the left and right rear wheels. In this method, firstly, the average wheel turning angles of the vehicle are obtained, including the average turning angles of the left and right front wheels and the average turning angles of the left and right rear wheels; then, based on the average wheel turning angles and a preset mapping relationship, the turning angle difference between the left and right rear wheels is obtained; finally, the corresponding turning angles of the left and right rear wheels are obtained using the obtained average wheel turning angles and the turning angle differences between the left and right rear wheels.

[0036] Here, in this preset mapping relationship, the average steering angle of the left and right front wheels is used as the independent variable, or the steering angle of each of the left and right front wheels obtained from the average steering angle of the left and right front wheels is used as the independent variable, to obtain the dependent variable—the steering angle difference between the left and right rear wheels. Since this preset mapping relationship is designed to make the Ackerman ratio reach a preset threshold (e.g., 90% to 100%), the steering angle of the left and right rear wheels calculated by this control method, and the control of the left and right rear wheels based on it, can improve the Ackerman ratio, thereby improving steering performance and reducing tire wear.

[0037] The concept of Ackermann's law is shown in the following formula (1):

[0038] Where Ackerman is the Ackerman law, θ i θ is the actual turning angle of the inside front wheel used for turning. o θ is the actual steering angle of the outer front wheel used for turning. id The ideal turning angle for the inner front wheel of the vehicle when turning. That is, when the turning angle of the outer front wheel is taken as a quantifier, the Ackermann ratio is the ratio between a first difference and a second difference, where the first difference is the actual turning angle θ of the inner front wheel of the vehicle. i The actual steering angle θ of the outer front wheel o The difference between the two values, the second difference being the ideal steering angle θ of the vehicle's inner front wheel. id The actual steering angle θ of the outer front wheel o The difference between them.

[0039] Alternatively, the concept of the Ackermann law can also be expressed as the following formula (2):

[0040] Where Ackerman is the Ackerman law, θ iθ is the actual turning angle of the inside front wheel used for turning. o θ is the actual steering angle of the outer front wheel used for turning. od The ideal steering angle for the outer front wheel of the vehicle when turning. That is, when the steering angle of the inner front wheel is taken as a quantifier, the Ackerman ratio is the ratio between the first difference and the third difference, where the first difference is the actual steering angle θ of the vehicle's inner front wheel. i The actual steering angle θ of the outer front wheel o The difference between the two values, the third difference is the actual steering angle θ of the vehicle's inner front wheel. i The ideal steering angle θ of the outer front wheel od The difference between them.

[0041] Figure 2 shows a vehicle with ideal Ackermann steering when there is no rear-wheel steering. In this case, the turning centers of the front and rear axles coincide, and all four wheels can roll purely. However, conventional vehicles, due to layout limitations, cannot achieve 100% Ackermann steering, i.e., the ideal Ackermann steering. In this case, as shown in Figure 3, the turning centers of the front and rear axles are not aligned. This misalignment causes tire deformation, creating a slip angle that shifts the vehicle's actual center of motion to the same point, leading to tire wear. Furthermore, in winter, the tires harden, drastically reducing the slip angle limit. A larger slip angle in this condition can easily produce abnormal noises.

[0042] In the embodiments of this application, since the rear wheel steering can be controlled, and the calculation of the rear wheel steering angle is based on a mapping relationship designed to improve the Ackerman ratio, under certain conditions, the Ackerman ratio can reach over 90%, or even 100%. This ensures that the turning center of the front axle coincides with or is nearly coincident with the turning center of the rear axle, and both the front and rear axle wheels roll purely as much as possible, without initial lateral slip due to the different centers of motion of the front and rear suspension tires. In this situation, the tires do not produce initial lateral slip, resulting in less uneven tire wear and reduced tire wear. Simultaneously, the tire's slip angle has an upper limit. Since the tire's trajectory does not produce an initial slip angle, the distance from the slip angle limit is large, providing more lateral force and improving the vehicle's lateral limits. Furthermore, in winter, the tires harden, and the slip angle limit decreases sharply. At this time, a large slip angle can easily produce abnormal noise. The rear wheel steering scheme of this application effectively reduces the tire slip angle, reducing the probability of abnormal tire noise in winter.

[0043] In one embodiment of this application, step S120, which involves obtaining the angle difference between the left and right rear wheels based on the average wheel angle and a preset mapping relationship, may include: obtaining the actual angle of the inner front wheel used for turning based on the average angle of the left and right front wheels; obtaining the ideal angle of the inner front wheel when the Ackerman ratio reaches 100% based on the actual angle of the inner front wheel; and obtaining the angle difference between the left and right rear wheels based on the ideal angle of the inner front wheel and a first preset mapping relationship, wherein the first preset mapping relationship is a preset mapping relationship between the ideal angle of the inner front wheel and the angle difference between the left and right rear wheels.

[0044] In this embodiment, the aforementioned formula (1) is used. That is, when the steering angle of the outer front wheel is taken as a quantifier, the Ackerman ratio is the ratio between the first difference and the second difference, where the first difference is the difference between the actual steering angle of the inner front wheel and the actual steering angle of the outer front wheel, and the second difference is the difference between the ideal steering angle of the inner front wheel and the actual steering angle of the outer front wheel. Based on this, in order for the Ackerman ratio to reach a preset threshold, for example, 100%, the ideal steering angle of the inner front wheel needs to be equal to the actual steering angle of the inner front wheel. The actual turning angle of the inner front wheel can be obtained from the steering wheel angle signal. Therefore, it is only necessary to design a mapping relationship (called the first preset mapping relationship) so that the ideal turning angle of the inner front wheel and the difference in turning angle between the left and right rear wheels are mapped. The following can be obtained: the average turning angle of the left and right front wheels is obtained from the steering wheel angle signal, then the actual turning angle of the inner front wheel is obtained, then the ideal turning angle of the inner front wheel is obtained (where the ideal turning angle of the inner front wheel is equal to the actual turning angle of the inner front wheel), and then the difference in turning angle between the left and right rear wheels is obtained through the first preset mapping relationship.

[0045] In a simpler example, since the ideal turning angle of the inner front wheel is equal to the actual turning angle of the inner front wheel when the Ackerman ratio reaches 100%, the mapping relationship between the actual turning angle of the inner front wheel and the turning angle difference between the left and right rear wheels can also be directly designed (called the third preset mapping relationship). The result is as follows: the average turning angle of the left and right front wheels is obtained from the steering wheel turning angle signal, and then the actual turning angle of the inner front wheel is obtained. Then, the turning angle difference between the left and right rear wheels is obtained through the third preset mapping relationship.

[0046] In a simpler example, since the ideal turning angle of the inner front wheel is equal to the actual turning angle of the inner front wheel when the Ackerman ratio reaches 100%, and the actual turning angle of the inner front wheel can be obtained from the average turning angle of the left and right front wheels, the mapping relationship between the average turning angle of the left and right front wheels and the turning angle difference of the left and right rear wheels can also be directly designed (called the fourth preset mapping relationship), which is as follows: the average turning angle of the left and right front wheels is obtained from the steering wheel turning angle signal, and then the turning angle difference of the left and right rear wheels is obtained through the fourth preset mapping relationship.

[0047] In another embodiment of this application, step S120, which obtains the angle difference between the left and right rear wheels based on the average wheel angle and a preset mapping relationship, includes: obtaining the actual angle of the outer front wheel used for turning based on the average angle of the left and right front wheels; obtaining the ideal angle of the outer front wheel when the Ackerman ratio reaches 100% based on the actual angle of the outer front wheel; and obtaining the angle difference between the left and right rear wheels based on the ideal angle of the outer front wheel and a second preset mapping relationship, wherein the second preset mapping relationship is a preset mapping relationship between the ideal angle of the outer front wheel and the angle difference between the left and right rear wheels.

[0048] In this embodiment, the aforementioned formula (2) is used. That is, when the turning angle of the inner front wheel is used as a quantifier, the Ackerman ratio is the ratio between the first difference and the third difference, where the first difference is the difference between the actual turning angle of the inner front wheel and the actual turning angle of the outer front wheel, and the third difference is the difference between the actual turning angle of the inner front wheel and the ideal turning angle of the outer front wheel. Based on this, in order to make the Ackerman ratio reach a preset threshold, for example, 100%, the ideal turning angle of the outer front wheel needs to be equal to the actual turning angle of the outer front wheel. The actual turning angle of the outer front wheel can be obtained from the steering wheel angle signal, so it is only necessary to design a mapping relationship (called the second preset mapping relationship) so that the ideal turning angle of the outer front wheel and the difference in turning angles of the left and right rear wheels are mapped, and the following can be obtained: the average turning angle of the left and right front wheels is obtained from the steering wheel angle signal, and then the actual turning angle of the outer front wheel is obtained, and then the ideal turning angle of the outer front wheel is obtained (where the ideal turning angle of the outer front wheel is equal to the actual turning angle of the outer front wheel), and then the difference in turning angles of the left and right rear wheels is obtained through the second preset mapping relationship.

[0049] In a simpler example, since the ideal turning angle of the outer front wheel is equal to the actual turning angle of the outer front wheel when the Ackerman ratio reaches 100%, the mapping relationship between the actual turning angle of the outer front wheel and the turning angle difference between the left and right rear wheels can also be directly designed (called the fifth preset mapping relationship), which can be obtained as follows: the average turning angle of the left and right front wheels is obtained from the steering wheel turning angle signal, and then the actual turning angle of the outer front wheel is obtained, and then the turning angle difference between the left and right rear wheels is obtained through the fifth preset mapping relationship.

[0050] In a simpler example, since the ideal steering angle of the outer front wheel is equal to the actual steering angle of the outer front wheel when the Ackerman ratio reaches 100%, and the actual steering angle of the outer front wheel can be obtained from the average steering angle of the left and right front wheels, the mapping relationship between the average steering angle of the left and right front wheels and the steering angle difference of the left and right rear wheels can also be directly designed (called the fourth preset mapping relationship, which is the same as described above), and the following can be obtained: the average steering angle of the left and right front wheels is obtained from the steering wheel angle signal, and then the steering angle difference of the left and right rear wheels is obtained through the fourth preset mapping relationship.

[0051] In embodiments of this application, obtaining the average turning angle of the left and right rear wheels of a vehicle based on the average turning angle of the left and right front wheels may include: obtaining the vehicle speed; obtaining a proportionality coefficient between the average turning angle of the left and right rear wheels and the average turning angle of the left and right front wheels based on a preset function, wherein the independent variable of the preset function is the vehicle speed and the dependent variable of the preset function is the proportionality coefficient; and multiplying the average turning angle of the left and right front wheels by the proportionality coefficient to obtain the average turning angle of the left and right rear wheels.

[0052] For example, suppose the vehicle speed is represented by v, the preset function is represented by f, and the average steering angle of the left and right front wheels is represented by θ. f The average steering angle of the left and right rear wheels is expressed as θ. r Let the proportionality constant be k. Then, it can be expressed by the following formulas (3) and (4): θ r =k×θ f (3) k=f(v) (4)

[0053] Among them, the average steering angle θ of the left and right front wheels f The steering wheel angle signal can be obtained from the steering wheel angle sensor. Vehicle speed can be obtained from the vehicle speed sensor.

[0054] In the embodiments of this application, when the vehicle speed is less than the preset speed, the proportional coefficient is negative, and the turning direction of the left and right rear wheels is opposite to that of the left and right front wheels; when the vehicle speed is not less than the preset speed, the proportional coefficient is positive, and the turning direction of the left and right rear wheels is in the same direction as that of the left and right front wheels. Continuing with the example described above, in formula (4), f can be a piecewise function: when the vehicle speed is less than a certain value, k is negative, making the average turning angle θ of the left and right front wheels... f The average steering angle θ of the left and right rear wheels r One value is positive, and the other is negative, ensuring that the turning directions of the left and right rear wheels are opposite to those of the left and right front wheels; when the vehicle speed is not less than this value, k is positive, making the average turning angle θ of the left and right front wheels... f The average steering angle θ of the left and right rear wheels r Both values ​​are either positive or both are negative, ensuring that the turning direction of the left and right rear wheels is the same as that of the left and right front wheels. The advantage of this design is that:

[0055] When the vehicle speed is below the speed threshold, the rear wheel steering angle is opposite to the front wheel steering angle, which reduces the turning diameter. In this application, when the rear wheels steer, the inner rear wheel steering angle is greater than the outer rear wheel steering angle. Taking a left turn as an example, the left rear wheel steering angle is greater than the right rear wheel steering angle, and the relationship between the front and rear wheel steering angles allows the steering center of the front wheels to coincide with the steering center of the rear wheels, as shown in Figure 4. At this time, the vehicle's Ackerman ratio reaches 100%, and both the front and rear axle wheels are rolling purely, without initial lateral slip due to the different centers of motion of the front and rear suspension tires. In this situation, the tires do not produce initial lateral slip, resulting in less tire wear and reduced tire wear. At the same time, the tire's slip angle has an upper limit. Since the tire's trajectory does not produce an initial slip angle, the distance from the slip angle limit is large, providing more lateral force and improving the vehicle's lateral limits. In winter, the tires harden, and the slip angle limit decreases sharply. At this time, a large slip angle is very likely to produce abnormal noise. The rear wheel steering scheme of this application effectively reduces the tire slip angle and reduces the probability of abnormal tire noise in winter.

[0056] When a vehicle reaches a certain speed, the tires will generate an initial sideslip angle due to lateral forces. At this point, when the inner rear wheel's turning angle is greater than that of the outer rear wheel, the turning centers of the two front axle wheels and the two rear axle wheels can be essentially aligned, as shown in Figure 5, effectively improving the Ackerman ratio. In this situation, the lateral rubber deformation of the front and rear tires is less than that of vehicles without rear-wheel steering or other existing rear-wheel steering vehicles. Under these conditions, tire lateral wear is reduced. Similarly, in low winter temperatures, the tire carcass hardens, and lateral deformation can easily produce a creaking noise. The rear-wheel steering control method of this application can effectively reduce the tire sideslip angle and decrease the probability of tire noise.

[0057] In general, when the vehicle speed is below the threshold, the rear wheel steering angle is opposite to that of the front wheels, which reduces the turning diameter. Simultaneously, the inner rear wheel steering angle is greater than the outer rear wheel steering angle, achieving a higher Ackerman ratio and reducing tire wear. When the vehicle speed is above the threshold, the rear wheel steering angle is in the same direction as the front wheels, which enhances rear axle stability. Again, the inner rear wheel steering angle is greater than the outer rear wheel steering angle, achieving a higher Ackerman ratio and reducing tire wear.

[0058] In the embodiments of this application, step S130, which determines the turning angles of the left and right rear wheels based on the average turning angle of the wheels and the difference in turning angles between the left and right wheels, may include: multiplying the difference in turning angles between the left and right rear wheels by a preset coefficient to obtain a turning angle offset, wherein the preset coefficient is greater than 0 and less than 1; adding the turning angle offset to the average turning angle of the left and right rear wheels to obtain the turning angle of the inner rear wheel; and subtracting the turning angle offset from the average turning angle of the left and right rear wheels to obtain the turning angle of the outer rear wheel.

[0059] For example, the angle difference between the left and right rear wheels, obtained earlier based on the average steering angle of the left and right front wheels and a preset mapping relationship, is expressed by formula (5): Δθr =f(θ) f (5)

[0060] Where, Δθ r θ is the difference in steering angle between the left and right rear wheels. f Let f be the average turning angle of the left and right front wheels, and f be a preset mapping relationship. Let θ be the turning angle of the inner rear wheel used for turning. ri The steering angle of the outer rear wheel is represented by θ. ro The average steering angle of the left and right rear wheels is θ r Therefore, the turning angles of the inner and outer rear wheels are expressed by formulas (6) and (7), respectively: θ ri =θ r +0.5Δθ r (6) θ ro =θ r -0.5Δθ r (7)

[0061] In this example, the steering angle difference Δθ between the left and right rear wheels is... r Multiply by a preset coefficient of 0.5 to obtain the angular offset of 0.5Δθ. r The average steering angle θ of the left and right rear wheels r Add a rotational offset of 0.5Δθ r The turning angle θ of the inner rear wheel is obtained. ri The average steering angle θ of the left and right rear wheels r Reduce the rotational offset by 0.5Δθ r The steering angle θ of the outer rear wheel is obtained. ro .

[0062] The above exemplarily illustrates a vehicle rear-wheel steering control method 100 according to an embodiment of this application. Based on the above description, the vehicle rear-wheel steering control method 100 according to an embodiment of this application adjusts the rear wheel steering angle through a reasonable control strategy, achieving better steering performance than other rear-wheel steering methods, improving the steering limit grip, reducing tire wear, and reducing the probability of tire low-temperature abnormal noise.

[0063] The following description, in conjunction with FIG6, describes a vehicle rear-wheel steering control device according to another aspect of this application. FIG6 shows a schematic structural block diagram of a vehicle rear-wheel steering control device 600 according to an embodiment of this application. As shown in FIG6, the vehicle rear-wheel steering control device 600 includes a memory 610 and a processor 620, wherein the memory 610 stores a computer-executable program executed by the processor, and when the computer-executable program is executed by the processor 620, the processor 620 performs the aforementioned vehicle rear-wheel steering control method 100. The vehicle rear-wheel steering control method 100 has been described in detail above, and those skilled in the art can understand the operation of the processor 620 in conjunction with the foregoing description; for the sake of brevity, it will not be described again here.

[0064] The following describes a vehicle rear-wheel steering control system according to another aspect of this application with reference to FIG. 7. FIG. 7 shows a schematic structural block diagram of a vehicle rear-wheel steering control system 700 according to an embodiment of this application. As shown in FIG. 7, the vehicle rear-wheel steering control system 700 includes a sensor 710, a left rear-wheel steering unit 720, a right rear-wheel steering unit 730, and a vehicle rear-wheel steering control device 740. The vehicle rear-wheel steering control device 740 can be the vehicle rear-wheel steering control device 600 described above, which executes the vehicle rear-wheel steering control method 100 described above. Specifically, the vehicle rear-wheel steering control device 740 can obtain the average wheel angle of the vehicle from the sensor 710 (such as a steering wheel angle sensor), determine the respective steering angles of the left and right rear wheels based on the average wheel angle, generate a left rear wheel steering angle signal and a right rear wheel steering angle signal, and send the left rear wheel steering angle signal and the right rear wheel steering angle signal to the left rear wheel steering unit 720 and the right rear wheel steering unit 730, respectively. In this process, the vehicle speed from a vehicle speed sensor can also be used, as described above. The left rear wheel steering unit 720 is used to control the left rear wheel based on the left rear wheel steering angle signal. The right rear wheel steering unit 730 is used to control the right rear wheel based on the right rear wheel steering angle signal. The vehicle rear wheel steering control method 100 executed by the vehicle rear wheel steering control device 600 has been described in detail above. Those skilled in the art can understand the operation of the vehicle rear wheel steering control device 740 in conjunction with the above description. For the sake of brevity, it will not be described again here.

[0065] The operation flowchart of the vehicle's rear-wheel steering control system 700 is shown in Figure 8 (where the electronic control center in Figure 8 can be equivalent to the vehicle's rear-wheel steering control device 740). When the vehicle speed is below a threshold, the rear wheel steering angle is opposite to that of the front wheels, which reduces the turning diameter. Simultaneously, the inner rear wheel steering angle is greater than the outer rear wheel steering angle, achieving a higher Ackerman ratio and reducing tire wear. When the vehicle speed is above the threshold, the rear wheel steering angle is in the same direction as the front wheels, enhancing rear axle stability. Again, the inner rear wheel steering angle is greater than the outer rear wheel steering angle, achieving a higher Ackerman ratio and reducing tire wear.

[0066] According to another aspect of this application, a vehicle is also provided, the vehicle including the aforementioned rear wheel steering control device 600 or the aforementioned rear wheel steering control system 700.

[0067] According to another aspect of this application, a storage medium is also provided, on which a computer program executed by a processor is stored, wherein when the computer program is executed by the processor, the processor performs the above-described vehicle rear wheel steering control method 100.

[0068] According to another aspect of this application, a computer program is provided that, when run by a processor, causes the processor to execute the aforementioned vehicle rear wheel steering control method 100.

[0069] Based on the above description, the vehicle rear wheel steering control method, device, system and vehicle according to the embodiments of this application can adjust the rear wheel steering angle through a reasonable control strategy, which can achieve better steering performance than other rear wheel steering methods, improve the steering limit grip and reduce tire wear, and reduce the probability of tire low temperature abnormal noise.

[0070] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0071] Those skilled in the art will recognize that the elements and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0072] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of elements is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple elements or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0073] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0074] Similarly, it should be understood that, in order to streamline this application and aid in understanding one or more of the various inventive aspects, features of this application may sometimes be grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, its inventive point lies in solving the corresponding technical problem with features fewer than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0075] Those skilled in the art will understand that, apart from the mutual exclusion of features, any combination of all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or elements of any method or apparatus so disclosed may be employed. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0076] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0077] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules according to the embodiments of this application. This application can also be implemented as a program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such a program implementing this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0078] It should be noted that the above embodiments are illustrative of this application and not limiting of it, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the claims listing several elements for vehicle rear-wheel steering control, several of these vehicle refrigerator control devices may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0079] The above description is merely a specific embodiment or illustration of the embodiments of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A method for controlling the rear-wheel steering of a vehicle, wherein, The method includes: Obtain the average wheel angle of the vehicle; The difference in steering angle between the left and right rear wheels is determined based on the average wheel steering angle and a preset mapping relationship, wherein the preset mapping relationship is a mapping relationship designed to make the Ackerman ratio reach a preset threshold. Based on the average turning angle of the wheels and the difference in turning angle between the left and right rear wheels, the turning angle of each of the left and right rear wheels is determined; and, The left and right rear wheels of the vehicle are controlled based on the respective turning angles of the left and right rear wheels.

2. The method according to claim 1, wherein, The acquisition of the vehicle's average wheel angle includes: Acquire the steering wheel angle signal, and based on the steering wheel angle signal, obtain the average steering angle of the left and right front wheels; and, The average steering angle of the left and right rear wheels is obtained based on the average steering angle of the left and right front wheels.

3. The method according to claim 2, wherein, The determination of the steering angle difference between the left and right rear wheels based on the average wheel steering angle and a preset mapping relationship includes: The actual turning angle of the inner front wheel used for turning is obtained based on the average turning angle of the left and right front wheels; The ideal steering angle of the inner front wheel when the Ackerman ratio reaches 100% is obtained based on the actual steering angle of the inner front wheel; and... The angle difference between the left and right rear wheels is obtained based on the ideal turning angle of the inner front wheel and the first preset mapping relationship.

4. The method according to claim 3, wherein, The first preset mapping relationship is the preset mapping relationship between the ideal turning angle of the inner front wheel and the difference in turning angle between the left and right rear wheels.

5. The method according to claim 2, wherein, The determination of the steering angle difference between the left and right rear wheels based on the average wheel steering angle and a preset mapping relationship includes: The actual turning angle of the outer front wheel used for turning is obtained based on the average turning angle of the left and right front wheels; The ideal steering angle of the outer front wheel when the Ackerman ratio reaches 100% is obtained based on the actual steering angle of the outer front wheel; and... The angle difference between the left and right rear wheels is obtained based on the ideal turning angle of the outer front wheel and the second preset mapping relationship.

6. The method according to claim 5, wherein, The second preset mapping relationship is a preset mapping relationship between the ideal turning angle of the outer front wheel and the turning angle difference between the left and right rear wheels.

7. The method according to any one of claims 2 to 6, wherein, The step of obtaining the average steering angle of the left and right rear wheels based on the average steering angle of the left and right front wheels includes: Obtain the vehicle speed; The proportionality coefficient between the average steering angle of the left and right rear wheels and the average steering angle of the left and right front wheels is obtained based on a preset function, wherein the independent variable of the preset function is the vehicle speed, and the dependent variable of the preset function is the proportionality coefficient; and, The average turning angle of the left and right front wheels is multiplied by the proportional coefficient to obtain the average turning angle of the left and right rear wheels.

8. The method according to claim 7, wherein, In response to the vehicle speed being less than a preset speed, the proportional coefficient becomes negative, and the turning direction of the left and right rear wheels is opposite to the turning direction of the left and right front wheels.

9. The method according to claim 7, wherein, In response to the vehicle speed being not less than the preset vehicle speed, the proportional coefficient is a positive number, and the turning direction of the left and right rear wheels is the same as the turning direction of the left and right front wheels.

10. The method according to any one of claims 2 to 9, wherein, Determining the rotation angle of each of the left and right rear wheels based on the average rotation angle of the wheel and the rotation angle difference between the left and right rear wheels includes: The angle difference between the left and right rear wheels is multiplied by a preset coefficient to obtain the angle offset, wherein the preset coefficient is greater than 0 and less than 1; The angle of the inner rear wheel is obtained by adding the average steering angle of the left and right rear wheels to the steering angle offset; and, The angle of the outer rear wheel is obtained by subtracting the angle offset from the average angle of the left and right rear wheels.

11. A vehicle rear-wheel steering control device, wherein, The control device includes a memory and a processor, wherein the memory stores a computer-executable program that is executed by the processor, and the computer-executable program, when executed by the processor, causes the processor to perform the vehicle rear-wheel steering control method as described in any one of claims 1-10.

12. A vehicle rear-wheel steering control system, wherein, The control system includes sensors, a left rear wheel steering gear, a right rear wheel steering gear, and the vehicle rear wheel steering control device as described in claim 11, wherein: The vehicle rear wheel steering control device is used to obtain the average wheel angle of the vehicle from the sensor, determine the respective steering angle of the left and right rear wheels based on the average wheel angle, generate a left rear wheel steering angle signal and a right rear wheel steering angle signal, and send the left rear wheel steering angle signal and the right rear wheel steering angle signal to the left rear wheel steering gear and the right rear wheel steering gear respectively. The left rear wheel steering mechanism is used to control the left rear wheel based on the left rear wheel steering angle signal; and The right rear wheel steering system is used to control the right rear wheel based on the right rear wheel steering angle signal.

13. A vehicle, wherein, The vehicle includes the rear-wheel steering control device of claim 11 or the rear-wheel steering control system of claim 12.

14. A storage medium applied to the rear-wheel steering control method of the vehicle shown in claim 1, wherein, The storage medium stores computer instructions that are executed by a processor, which, when executed by the processor, cause the processor to perform the vehicle rear-wheel steering control method as described in any one of claims 1-10.

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