A control method and system for a U-turn of a vehicle with rear-wheel steering

Abstract

A control method and system for a U-turn of a vehicle with rear-wheel steering, belonging to the field of vehicle control, includes selecting two points on a proportional control curve as the starting point and end point of a hysteresis control curve, the starting point being the starting point of the steering wheel returning to center, and the end point being the point where the rear wheel angle is less than the maximum rear wheel angle, and the slope of the hysteresis control curve is fixed; after the vehicle enters the U-turn condition, it is determined whether the product of the steering wheel angle and the steering wheel angular velocity is positive, and if so, the proportional control curve is used to control the front and rear wheel angles; if not, the hysteresis control curve is used to control the front and rear wheel angles. This application uses the hysteresis control curve to control the front and rear wheels to return to center together when the steering wheel begins to return to center, thereby avoiding vehicle body instability caused by the lag of the rear wheel returning to center during the initial return stage. In other time periods other than the initial return to center, the traditional proportional control curve is still used, thereby reducing changes to the existing system and improving practicality.

Description

Technical Field

[0001] The present application relates to the field of vehicle control, and in particular to a control method and system for a vehicle with rear-wheel steering making a U-turn. Background Art

[0002] Nowadays, more and more new energy vehicles have rear-wheel steering functions. This function can control the rear wheel angle to be opposite to the front wheel angle at low speeds, reduce the turning radius, and increase the vehicle's maneuverability. At high speeds, it can control the rear wheel angle to be in the same direction as the front wheel angle to increase stability.

[0003] Generally, the rear wheel steering angle is controlled by proportional control, which is related to the size of the front wheel turning angle. When the vehicle makes a U-turn, the driver will first turn the steering wheel to the full angle, and the front wheel turning angle is the largest. At this time, the rear wheel turning angle is also the largest, and the front and rear wheels turn in opposite directions. The vehicle turns around. After the front of the vehicle is turned around, the steering wheel returns to the center, and the front wheel turning angle changes with the steering wheel angle. However, due to the proportional relationship between the front wheel turning angle and the rear wheel turning angle, the rear wheel turning angle will still maintain the maximum angle when it is just started to return to the center. After returning to a certain angle, the rear wheel will suddenly decrease back to the center. The sudden decrease in the rear wheel turning angle will cause the rear axle of the vehicle to suddenly produce a yaw in the opposite direction of the vehicle body, causing the rear axle of the vehicle to shake, affecting the driving experience.

[0004] For example, the angle control of the rear wheel steering uses a proportional control curve, such as Figure 1 As shown in the figure, the x-axis of the curve is the front wheel angle, and the y-axis is the rear wheel angle. There is a proportional relationship between the steering wheel angle and the front wheel angle based on a mechanical connection. That is, when the steering wheel angle is turned to the left, the front wheels also turn to the left to the maximum, and when the steering wheel angle is turned to the right, the front wheels also turn to the right to the maximum. On some models, the maximum steering wheel angle can reach 450°, and accordingly, the maximum front wheel angle can reach 40°.

[0005] Reference Figure 1As shown, between points A and C, the front wheel angle increases with the steering wheel angle, and the rear wheel angle also increases with the front wheel angle, but the front and rear wheels turn in opposite directions. At point A, the steering wheel angle is 200°, the front wheel angle af is 20°, and the rear wheel angle ar is 8°. At point C, the steering wheel angle is 330°, the front wheel angle cf is 30°, and the rear wheel angle cr reaches its maximum of 10°. From point C onward, the front wheel angle continues to increase with the steering wheel angle, while the rear wheel angle remains unchanged. At point B, the steering wheel angle is 360°, the front wheel angle bf is 35°, and the rear wheel angle br is 10°, where cr = br. From point B onward, the steering wheel angle can continue to increase, with the front wheel angle increasing while the rear wheel angle remains unchanged until the vehicle completes the U-turn and the steering wheel begins to return to the center. The vehicle then follows the proportional control curve, returning from the final point through points B, C, and A to the origin, o.

[0006] Assuming that point B is selected as the starting point for the steering wheel to return to the center, in the process of returning from point B to point C, the steering wheel is in the initial stage of returning to the center. The front wheel angle begins to return to the center as the steering wheel returns to the center, the vehicle runs smoothly, and the rear wheel angle remains unchanged. After reaching point C, the rear wheel begins to return to the center. The sudden decrease in the rear wheel angle will cause the rear axle of the vehicle to suddenly produce a yaw in the opposite direction of the body, causing the rear axle of the vehicle to shake, affecting the driving experience.

[0007] Therefore, how to control a vehicle with rear-wheel steering during a U-turn is a problem that needs to be solved. Summary of the Invention

[0008] The present application provides a control method and system for a vehicle with rear-wheel steering to perform a U-turn, which can solve the technical problem in the prior art that the vehicle body is prone to instability during a U-turn.

[0009] In a first aspect, an embodiment of the present application provides a control method for a vehicle with rear-wheel steering during a U-turn, the method comprising:

[0010] Two points are selected on the proportional control curve as the starting point and ending point of the hysteresis control curve. The starting point is the starting point of the steering wheel returning to center, and the ending point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve.

[0011] After determining that the vehicle has entered a U-turn condition, determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive. If so, a proportional control curve is used to control the front and rear wheel angles; if not, a hysteresis control curve is used to control the front and rear wheel angles.

[0012] In combination with the first aspect, in one embodiment, the front wheel steering angle at the starting point of the hysteresis control curve is no greater than the maximum front wheel steering angle, and the rear wheel steering angle is the maximum rear wheel steering angle;

[0013] The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

[0014] In combination with the first aspect, in one embodiment, the method further includes:

[0015] The road condition information of the U-shaped road condition and the historical operation information of the vehicle are collected in advance, and the starting point of the steering wheel returning to the center is estimated by combining the road condition information and the operation information.

[0016] In combination with the first aspect, in one embodiment, the method further includes:

[0017] When the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel turning angle is greater than the rear wheel turning angle at the end point, it is determined that the vehicle enters a U-turn condition.

[0018] In conjunction with the first aspect, in one embodiment, when the hysteresis control curve is adopted, the rear wheel steering angle is calculated using the following formula:

[0019]

[0020] Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

[0021] In a second aspect, an embodiment of the present application provides a control system for a vehicle with rear-wheel steering during a U-turn, the system comprising:

[0022] The curve configuration module is used to select two points on the proportional control curve as the starting point and end point of the hysteresis control curve. The starting point is the starting point of the steering wheel returning to center, and the end point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve.

[0023] The control module is used to determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive after determining that the vehicle enters a U-turn condition. If so, the front wheel angle and the rear wheel angle are controlled using a proportional control curve; if not, the front wheel angle and the rear wheel angle are controlled using a hysteresis control curve.

[0024] In conjunction with the second aspect, in one embodiment, the front wheel steering angle at the starting point of the hysteresis control curve is no greater than the maximum front wheel steering angle, and the rear wheel steering angle is the maximum rear wheel steering angle;

[0025] The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

[0026] In combination with the second aspect, in one embodiment, the curve configuration module is further used to pre-collect road condition information of U-shaped road conditions and historical vehicle operation information, and estimate the starting point of the steering wheel returning to the center position based on the road condition information and the operation information.

[0027] In combination with the second aspect, in one embodiment, the control module is further used to determine that the vehicle enters a U-turn condition when the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel angle is greater than the rear wheel angle at the end point.

[0028] In conjunction with the second aspect, in one embodiment, when the hysteresis control curve is adopted, the rear wheel steering angle is calculated using the following formula:

[0029]

[0030] Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

[0031] The beneficial effects of the technical solutions provided in the embodiments of the present application include:

[0032] By using a hysteresis control curve to control the front and rear wheels to return to center together when the steering wheel begins to return to center, vehicle instability caused by the lag of the rear wheel returning to center during the initial return phase can be avoided. During other time periods other than the initial return phase, the traditional proportional control curve is still used, minimizing changes to the existing system and improving practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of a proportional control curve in the prior art;

[0034] Figure 2 Schematic diagram of the proportional control curve and the hysteresis control curve in this application;

[0035] Figure 3 This is a flow chart of an embodiment of a control method for a U-turn of a vehicle with rear-wheel steering according to the present invention;

[0036] Figure 4 This is a functional module diagram of an embodiment of a control system for a U-turn of a vehicle with rear-wheel steering according to the present application. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0038] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0039] In a first aspect, an embodiment of the present application provides a control method for a vehicle with rear-wheel steering making a U-turn.

[0040] In one embodiment, referring to Figure 2 and Figure 3 , Figure 2 Schematic diagram of the proportional control curve and the hysteresis control curve in this application, Figure 3 This is a flow chart of an embodiment of a control method for a U-turn of a vehicle with rear-wheel steering according to the present invention. Figure 2 and Figure 3 As shown, the control method for a U-turn of a vehicle with rear-wheel steering includes:

[0041] Step S1: Select two points on the proportional control curve as the starting point and the end point of the hysteresis control curve. The starting point is the starting point of the steering wheel returning to the center position, and the end point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve.

[0042] Step S2: After determining that the vehicle has entered a U-turn condition, determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive. If so, use the proportional control curve to control the front and rear wheel angles. If not, use the hysteresis control curve to control the front and rear wheel angles.

[0043] In this embodiment, when the steering wheel begins to return to center, a hysteresis control curve is used to control the front and rear wheels to return to center together, thereby avoiding vehicle body instability caused by the lag of the rear wheel returning to center during the initial return phase. In other time periods other than the initial return phase, the traditional proportional control curve is still used, thereby reducing changes to the existing system and improving practicality.

[0044] In a specific embodiment, when the vehicle begins to enter a U-turn condition, a traditional proportional control curve is used, and the front wheel angle increases as the steering wheel angle increases, and the rear wheel angle increases in the opposite direction as the front wheel angle increases. When the rear wheel angle reaches a maximum, the front wheel angle and the steering wheel angle have not yet reached a maximum, and the front wheel angle and the steering wheel angle continue to increase. At a certain moment, the vehicle completes the U-turn and the steering wheel begins to return to the center. When the steering wheel returns to the center, the product of the steering wheel angle and the steering wheel angle speed is negative. At this time, the hysteresis control curve is switched to control the front wheel angle and the rear wheel angle to return to the center together. The starting point of the steering wheel returning to the center is the starting point of the hysteresis control curve. After the front wheel angle and the rear wheel angle reach the end point of the hysteresis control curve, the proportional control curve is switched back.

[0045] It should be noted that if it is determined that the steering wheel begins to return to the center position and the control mode has been switched to using the hysteresis control curve to control the front and rear wheel angles, if the steering wheel angle increases again, that is, when the product of the steering wheel angle and the steering wheel angle velocity is a positive number, the control of the rear wheel angle directly returns to normal proportional control and is output at the normal angle.

[0046] Furthermore, in one embodiment, the front wheel turning angle at the starting point of the hysteresis control curve is not greater than the maximum front wheel turning angle, and the rear wheel turning angle is the maximum rear wheel turning angle.

[0047] The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

[0048] In this embodiment, due to factors such as different drivers and different U-shaped road conditions, for example, some U-shaped road conditions have a relatively small curvature, while some U-shaped road conditions have a relatively large curvature. As a result, the point where the steering wheel starts to return to the center position is not necessarily the point of the maximum front wheel turning angle. Therefore, the hysteresis control curve can be generated based on the general proportional control curve. However, the slope of the hysteresis control curve in different scenarios is consistent.

[0049] The front wheel turning angle at the end point of the control curve must be less than the maximum front wheel turning angle, and the rear wheel turning angle can be 80% of the maximum rear wheel turning angle. For example, if the maximum rear wheel turning angle is 10°, the rear wheel turning angle at the end point can be selected as 8°.

[0050] Furthermore, in one embodiment, the above method further includes:

[0051] The road condition information of the U-shaped road condition and the historical operation information of the vehicle are collected in advance, and the starting point of the steering wheel returning to the center position is estimated by combining the road condition information and the operation information.

[0052] In this embodiment, taking into account factors such as different drivers and different U-shaped road conditions, it is possible to pre-collect multiple sets of training data and use deep learning models and other means to estimate the steering wheel starting return points that different drivers will choose under different U-shaped road conditions, thereby configuring a hysteresis control curve, thereby improving the control effect of the hysteresis control curve and avoiding sudden yaw of the rear axle.

[0053] Furthermore, in one embodiment, the above method further includes:

[0054] When the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel turning angle is greater than the rear wheel turning angle at the end point, it is determined that the vehicle enters a U-turn condition.

[0055] In this embodiment, the rear wheel turning angle of the vehicle is generally not too large. If a rear wheel turning angle is relatively large, for example, it is greater than the rear wheel turning angle at the end point, the vehicle is definitely turning, but it is impossible to determine whether it is turning in place or making a U-turn. At this time, a judgment is made based on the vehicle. If the real-time vehicle speed is greater than a preset minimum threshold, such as 5km / h, it can be determined that the vehicle has entered a U-turn condition. Thereafter, the front and rear wheels of the vehicle can be controlled based on the proportional control curve and the hysteresis control curve.

[0056] Furthermore, in one embodiment, when the hysteresis control curve is used, the rear wheel steering angle is calculated using the following formula (1):

[0057]

[0058] Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

[0059] In this embodiment, after the hysteresis control curve is used to control the front and rear wheel angles, S(sf, sr) at any point in the hysteresis curve is calculated using the above formula (1). Specifically, sf is calculated based on the steering wheel angle, and sr is calculated based on sf and the above formula (1). If the steering wheel is increased again during the process of returning to the center position, the front and rear wheel angles are immediately switched to the proportional control curve, and the new rear wheel angle is determined based on the front wheel angle before the switch.

[0060] In a specific embodiment, the present invention proposes a control method for a vehicle with rear-wheel steering during a U-turn, which can solve the problem of sudden yaw of the rear axle due to a sudden change in the rear wheel angle during the vehicle's steering wheel return process, resulting in a poor driving experience for the driver and passengers. The control method is divided into several steps:

[0061] Identify the working conditions of a U-turn. Assume that when the steering wheel angle is 330° (the steering wheel angle and the front wheel angle are in a proportional relationship based on mechanical relationship, for example, the front wheel angle is 30° at this time), the rear wheel angle reaches the maximum value such as 10°. When the rear wheel angle reaches ar = 8° (the rear wheel angle will not reach 8° during normal driving), and the vehicle speed is greater than 5 km / h (to avoid steering the wheel in place and ensure it is in a driving state), record the steering wheel angle af. At this time, it can be confirmed that the vehicle is in a large-angle U-turn working condition. As the steering wheel angle continues to increase, the rear wheel angle will also reach the maximum angle of 10°. When the product of the steering wheel angle and the steering wheel angular velocity is negative, record the steering wheel angle bf. Because the product of the steering wheel angle and the steering wheel angular velocity is negative, it indicates that the steering wheel is being straightened at this time. At this time, it is certain that the front wheel angle is greater than af, and the control angle of the rear wheel angle no longer follows the original proportional curve (proportional control curve) but enters another hysteresis curve mode. When in this mode, the rear wheel angle is calculated based on the above formula (1). When the front wheel angle < af, exit this angle control strategy, and the control angle of the rear wheel angle resumes normal proportional control. If during the activation of the strategy, the steering wheel angle increases again, that is, when the product of the steering wheel angle and the steering wheel angular velocity is positive, the control of the rear wheel angle directly resumes normal proportional control and outputs at the normal angle.

[0062] This solution can solve the problem that when a vehicle with rear-wheel steering makes a U-turn, due to the proportional control of the rear wheel angle, when the steering wheel is being straightened, the sudden change of the rear wheel angle deteriorates the yaw of the rear axle of the vehicle and generates an unpleasant driving experience.

[0063] In a second aspect, the embodiments of the present application further provide a control system for a vehicle with rear-wheel steering during a U-turn.

[0064] In one embodiment, refer to Figure 4 , Figure 4 is a schematic diagram of the functional modules of an embodiment of the control system for a vehicle with rear-wheel steering during a U-turn in the present application. As Figure 4 shown, the control system for a vehicle with rear-wheel steering during a U-turn includes:

[0065] Curve configuration module 1, which is used to select two points on the proportional control curve as the starting point and the ending point of the hysteresis control curve. The starting point is the starting point of the steering wheel straightening, and the ending point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve.

[0066] Control module 2, which is used to determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive after determining that the vehicle enters the U-turn working condition. If so, use the proportional control curve to control the front wheel angle and the rear wheel angle. If not, use the hysteresis control curve to control the front wheel angle and the rear wheel angle.

[0067] In this embodiment, when the steering wheel begins to return to center, a hysteresis control curve is used to control the front and rear wheels to return to center together, thereby avoiding vehicle body instability caused by the lag of the rear wheel returning to center during the initial return phase. In other time periods other than the initial return phase, the traditional proportional control curve is still used, thereby reducing changes to the existing system and improving practicality.

[0068] In a specific embodiment, when the vehicle begins to enter a U-turn condition, a traditional proportional control curve is used, and the front wheel angle increases as the steering wheel angle increases, and the rear wheel angle increases in the opposite direction as the front wheel angle increases. When the rear wheel angle reaches a maximum, the front wheel angle and the steering wheel angle have not yet reached a maximum, and the front wheel angle and the steering wheel angle continue to increase. At a certain moment, the vehicle completes the U-turn and the steering wheel begins to return to the center. When the steering wheel returns to the center, the product of the steering wheel angle and the steering wheel angle speed is negative. At this time, the hysteresis control curve is switched to control the front wheel angle and the rear wheel angle to return to the center together. The starting point of the steering wheel returning to the center is the starting point of the hysteresis control curve. After the front wheel angle and the rear wheel angle reach the end point of the hysteresis control curve, the proportional control curve is switched back.

[0069] It should be noted that if it is determined that the steering wheel begins to return to the center position and the control mode has been switched to using the hysteresis control curve to control the front and rear wheel angles, if the steering wheel angle increases again, that is, when the product of the steering wheel angle and the steering wheel angle velocity is a positive number, the control of the rear wheel angle directly returns to normal proportional control and is output at the normal angle.

[0070] Furthermore, in one embodiment, the front wheel steering angle at the starting point of the hysteresis control curve is not greater than the maximum front wheel steering angle, and the rear wheel steering angle is the maximum rear wheel steering angle;

[0071] The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

[0072] In this embodiment, due to factors such as different drivers and different U-shaped road conditions, for example, some U-shaped road conditions have a relatively small curvature, while some U-shaped road conditions have a relatively large curvature. As a result, the point where the steering wheel starts to return to the center position is not necessarily the point of the maximum front wheel turning angle. Therefore, the hysteresis control curve can be generated based on the general proportional control curve. However, the slope of the hysteresis control curve in different scenarios is consistent.

[0073] The front wheel turning angle at the end point of the control curve must be less than the maximum front wheel turning angle, and the rear wheel turning angle can be 80% of the maximum rear wheel turning angle. For example, if the maximum rear wheel turning angle is 10°, the rear wheel turning angle at the end point can be selected as 8°.

[0074] Furthermore, in one embodiment, the curve configuration module 1 is further configured to pre-collect road condition information of a U-shaped road condition and historical vehicle operation information, and estimate the steering wheel return start point based on the road condition information and the operation information.

[0075] In this embodiment, taking into account factors such as different drivers and different U-shaped road conditions, it is possible to pre-collect multiple sets of training data and use deep learning models and other means to estimate the steering wheel starting return points that different drivers will choose under different U-shaped road conditions, thereby configuring a hysteresis control curve, thereby improving the control effect of the hysteresis control curve and avoiding sudden yaw of the rear axle.

[0076] Furthermore, in one embodiment, the control module 2 is further configured to determine that the vehicle enters a U-turn condition when the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel turning angle is greater than the rear wheel turning angle at the end point.

[0077] In this embodiment, the rear wheel turning angle of the vehicle is generally not too large. If a rear wheel turning angle is relatively large, for example, it is greater than the rear wheel turning angle at the end point, the vehicle is definitely turning, but it is impossible to determine whether it is turning in place or making a U-turn. At this time, a judgment is made based on the vehicle. If the real-time vehicle speed is greater than a preset minimum threshold, such as 5km / h, it can be determined that the vehicle has entered a U-turn condition. Thereafter, the front and rear wheels of the vehicle can be controlled based on the proportional control curve and the hysteresis control curve.

[0078] Furthermore, in one embodiment, when the hysteresis control curve is used, the rear wheel steering angle is calculated using the following formula (1):

[0079]

[0080] Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

[0081] In this embodiment, after the hysteresis control curve is used to control the front and rear wheel angles, S(sf, sr) at any point in the hysteresis curve is calculated using the above formula (1). Specifically, sf is calculated based on the steering wheel angle, and sr is calculated based on sf and the above formula (1). If the steering wheel is increased again during the process of returning to the center position, the front and rear wheel angles are immediately switched to the proportional control curve, and the new rear wheel angle is determined based on the front wheel angle before the switch.

[0082] Among them, the functional implementation of each module in the control system for the above-mentioned U-turn of the rear-wheel steering vehicle corresponds to the various steps in the embodiment of the control method for the above-mentioned U-turn of the rear-wheel steering vehicle, and their functions and implementation processes will not be repeated here one by one.

[0083] On the third aspect, an embodiment of the present application provides a control device for a U-turn of a vehicle with rear-wheel steering. The control device for a U-turn of a vehicle with rear-wheel steering can be a personal computer (PC), a laptop computer, a server, or other device with data processing capabilities.

[0084] In an embodiment of the present application, a control device for a rear-wheel steering vehicle performing a U-turn may include a processor, a memory, a communication interface, and a communication bus.

[0085] The communication bus may be of any type and is used to interconnect the processor, memory, and communication interface.

[0086] Communication interfaces include input / output (I / O) interfaces, physical interfaces, and logical interfaces. These interfaces are used to interconnect components within the control device when a rear-wheel steering vehicle performs a U-turn, as well as interfaces used to interconnect the control device with other devices (such as other computing devices or user devices) when a rear-wheel steering vehicle performs a U-turn. Physical interfaces can be Ethernet, fiber optic, or ATM interfaces; user devices can be displays, keyboards, and other devices.

[0087] The memory can be various types of storage media, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), flash memory, optical storage, hard disk, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), etc.

[0088] The processor may be a general-purpose processor that can call a control program for a U-turn for a vehicle with rear-wheel steering stored in a memory and execute the control method for a U-turn for a vehicle with rear-wheel steering provided in the embodiments of the present application. For example, the general-purpose processor may be a central processing unit (CPU). The method executed when the control program for a U-turn for a vehicle with rear-wheel steering is called can be referred to in the various embodiments of the control method for a U-turn for a vehicle with rear-wheel steering provided in the present application, and will not be further described here.

[0089] In a fourth aspect, an embodiment of the present application also provides a computer-readable storage medium.

[0090] The computer-readable storage medium of the present application stores a control program for a U-turn of a vehicle with rear-wheel steering, wherein when the control program for a U-turn of a vehicle with rear-wheel steering is executed by a processor, the steps of the control method for a U-turn of a vehicle with rear-wheel steering as described above are implemented.

[0091] Among them, the method implemented when the control program for a rear-wheel steering vehicle making a U-turn is executed can refer to the various embodiments of the control method for a rear-wheel steering vehicle making a U-turn in this application, and will not be repeated here.

[0092] It should be noted that the serial numbers of the above-mentioned embodiments of the present application are for description only and do not represent the advantages or disadvantages of the embodiments.

[0093] The terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. The terms "first", "second" and "third" are used to distinguish different objects, etc., and do not represent a sequence, nor do they limit the "first", "second" and "third" to different types.

[0094] In the description of the embodiments of this application, the words "exemplary," "for example," or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary," "for example," or "for example" in the embodiments of this application should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary," "for example," or "for example" is intended to present the relevant concepts in a concrete manner.

[0095] In the description of the embodiments of the present application, unless otherwise specified, “ / ” means or, for example, A / B can mean A or B; “and / or” in the text is merely a description of the association relationship of associated objects, indicating that three relationships may exist, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, “multiple” refers to two or more than two.

[0096] In some processes described in the embodiments of the present application, multiple operations or steps are included that appear in a specific order. However, it should be understood that these operations or steps may not be performed in the order in which they appear in the embodiments of the present application or may be performed in parallel. The sequence numbers of the operations are only used to distinguish between different operations, and the sequence numbers themselves do not represent any order of execution. In addition, these processes may include more or fewer operations, and these operations or steps may be performed in sequence or in parallel, and these operations or steps may be combined.

[0097] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus the necessary general hardware platform, of course, it can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for enabling a terminal device to execute the methods described in each embodiment of the present application.

[0098] The above are only preferred embodiments of the present application and do not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A control method for a vehicle with rear-wheel steering making a U-turn, characterized in that: The method comprises: Two points are selected on the proportional control curve as the starting point and ending point of the hysteresis control curve. The starting point is the starting point of the steering wheel returning to center, and the ending point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve. After determining that the vehicle has entered a U-turn condition, determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive. If so, a proportional control curve is used to control the front and rear wheel angles; if not, a hysteresis control curve is used to control the front and rear wheel angles.

2. The control method for a rear-wheel steering vehicle making a U-turn according to claim 1, wherein: The front wheel turning angle at the starting point of the hysteresis control curve is not greater than the maximum front wheel turning angle, and the rear wheel turning angle is the maximum rear wheel turning angle; The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

3. The control method for a rear-wheel steering vehicle making a U-turn according to claim 1, wherein: The method further comprises: The road condition information of the U-shaped road condition and the historical operation information of the vehicle are collected in advance, and the starting point of the steering wheel returning to the center is estimated by combining the road condition information and the operation information.

4. The method for controlling a U-turn of a vehicle with rear-wheel steering according to claim 1, wherein: The method further comprises: When the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel turning angle is greater than the rear wheel turning angle at the end point, it is determined that the vehicle enters a U-turn condition.

5. The method for controlling a U-turn of a vehicle with rear-wheel steering according to claim 1, wherein: When the hysteresis control curve is used, the rear wheel steering angle is calculated using the following formula: Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

6. A control system for a U-turn of a vehicle with rear-wheel steering, characterized in that: The system comprises: The curve configuration module is used to select two points on the proportional control curve as the starting point and end point of the hysteresis control curve. The starting point is the starting point of the steering wheel returning to center, and the end point is the point where the rear wheel angle is less than the maximum rear wheel angle. The slope of the hysteresis control curve is fixed, and the hysteresis control curve is added on the basis of the proportional control curve. The control module is used to determine whether the product of the steering wheel angle and the steering wheel angular velocity is positive after determining that the vehicle enters a U-turn condition. If so, the front wheel angle and the rear wheel angle are controlled using a proportional control curve; if not, the front wheel angle and the rear wheel angle are controlled using a hysteresis control curve.

7. The control system for a U-turn of a rear-wheel steering vehicle according to claim 6, characterized in that: The front wheel turning angle at the starting point of the hysteresis control curve is not greater than the maximum front wheel turning angle, and the rear wheel turning angle is the maximum rear wheel turning angle; The front wheel turning angle at the end point of the hysteresis control curve is less than the maximum front wheel turning angle, and the rear wheel turning angle is the product of the maximum rear wheel turning angle and a preset percentage.

8. The control system for a U-turn of a rear-wheel steering vehicle according to claim 6, characterized in that: The curve configuration module is further used to pre-collect road condition information of the U-shaped road condition and historical operation information of the vehicle, and estimate the starting point of the steering wheel returning to the center position by combining the road condition information and the operation information.

9. The control system for a U-turn of a vehicle with rear-wheel steering according to claim 6, characterized in that: The control module is further configured to determine that the vehicle enters a U-turn condition when the real-time vehicle speed is greater than a preset minimum threshold and the real-time rear wheel turning angle is greater than the rear wheel turning angle at the end point.

10. The control system for a U-turn of a vehicle with rear-wheel steering according to claim 6, characterized in that: When the hysteresis control curve is used, the rear wheel steering angle is calculated using the following formula: Among them, sr represents the real-time front wheel angle, br represents the maximum rear wheel angle, ar represents the rear wheel angle at the end point, bf represents the front wheel angle at the starting point of the return, af represents the front wheel angle at the end point, and sf represents the real-time rear wheel angle.

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