CN118722850A - Rear wheel steering control method, system, device, storage medium and vehicle - Google Patents

Abstract

The present invention discloses a rear-wheel steering control method, system, device, storage medium and vehicle. The rear-wheel steering control method is applied to a vehicle with a rear-wheel steering system. The rear-wheel steering system includes a lead screw for controlling the rear-wheel steering of the vehicle, including: in response to the rear wheel starting to turn, obtaining the actual position angle of the lead screw and the target position angle of the lead screw, determining the difference between the actual position angle and the target position angle as the position angle deviation of the lead screw, obtaining the vehicle speed, and obtaining a first preset threshold value according to the vehicle speed; according to the position angle deviation being greater than or equal to the first preset threshold value, controlling the rear-wheel steering system to return the rear wheel to the correct position. When the position angle deviation of the lead screw exceeds the first preset threshold value, the rear wheel can be promptly controlled to return to the correct position, thereby reducing the lateral force of the vehicle body and ensuring the functional safety of the whole vehicle.

Description

Rear wheel steering control method, system, device, storage medium and vehicle

Technical Field

The present invention relates to the field of vehicle control technology, and in particular to a rear wheel steering control method, system, device, storage medium and vehicle.

Background Art

As people's pursuit of vehicle driving convenience continues to improve, in order to enhance product competitiveness, more and more vehicles on the market are equipped with active rear-wheel steering systems. Because the active rear-wheel steering system has a great impact on the handling stability of the vehicle, and it is a wire-controlled product, its functional safety is particularly important. Inappropriate functional safety control strategies will affect user experience or endanger user safety.

In the related technology, when controlling the rear-wheel steering, due to the influence of external road conditions, such as asphalt, cement, ice and other road surfaces, the friction coefficient and external load of the rear wheels may change, which may easily cause the system to overshoot the rear wheel angle. The rear wheel angle controlled by the active rear-wheel steering system has a great influence on the handling stability of the entire vehicle. A rear wheel angle of 1° will generate a lateral force of more than 1000N. Unexpected rear wheel angle deviation may cause the entire vehicle to run off the track, skid or even roll over, causing property damage and threatening the lives of drivers and passengers.

Summary of the invention

To this end, an object of an embodiment of the present invention is to provide a rear-wheel steering control method, system, device, storage medium and vehicle. When the position angle deviation of the screw exceeds a threshold, the rear wheel can be controlled to return to the straight position in time, thereby reducing the lateral force of the vehicle body and ensuring the functional safety of the entire vehicle.

According to a first aspect of an embodiment of the present invention, a rear-wheel steering control method is applied to a vehicle having a rear-wheel steering system, wherein the rear-wheel steering system comprises a lead screw for controlling the steering of the rear wheels of the vehicle, and the rear-wheel steering control method comprises: in response to the rear wheels starting to turn, obtaining an actual position angle of the lead screw and a target position angle of the lead screw, determining a difference between the actual position angle and the target position angle as a position angle deviation of the lead screw, and obtaining a first preset threshold value according to the vehicle speed; and controlling the rear-wheel steering system to straighten the rear wheels according to the position angle deviation being greater than or equal to the first preset threshold value.

The rear wheel steering control method according to the embodiment of the present invention has at least the following beneficial effects:

The present invention can determine whether the rear-wheel steering is overshooting by judging whether the position angle deviation of the lead screw is greater than the first preset threshold value corresponding to the current vehicle speed. That is, the steering angle deviation of the rear wheel is judged by the position angle deviation of the lead screw. The result is relatively accurate. When the position angle deviation of the lead screw is greater than the first preset threshold value, it indicates that the rear-wheel steering is overshooting. At this time, the rear wheel is controlled to return to the straight position by the rear-wheel steering system. It can be understood that the rear wheel returns to the zero position, which can reduce the lateral force of the vehicle body and ensure the functional safety of the whole vehicle.

According to some embodiments of the present invention, the rear-wheel steering control method also includes the following steps: in response to the rear wheel completing the steering, when the position angle deviation is less than zero and the absolute value of the position angle deviation is greater than or equal to the first preset threshold, controlling the rear wheel to continue steering until the screw reaches the target position angle.

According to some embodiments of the present invention, controlling the rear wheel to return to the positive position based on the position angle deviation being greater than or equal to the first preset threshold comprises: determining a second preset threshold based on the first preset threshold, the second preset threshold being less than the first preset threshold; when the position angle deviation is greater than or equal to the second preset threshold, controlling the lead screw to decelerate to zero at a preset deceleration and rotate at a preset safety speed until the actual position angle is zero.

According to some embodiments of the present invention, determining the second preset threshold according to the first preset threshold includes: calculating the second preset threshold using the following formula: The first preset threshold is the maximum tolerance value of the rear wheel angle deviation δ _zmi , the second preset threshold is δ _smi , the rotation speed of the screw is V _si , the preset reaction time of the system is t _f , and the preset deceleration of the screw is a _si .

According to some embodiments of the present invention, the preset safety speed is less than the preset deceleration.

According to some embodiments of the present invention, the vehicle is inversely proportional to the first preset value.

According to the second aspect of the embodiment of the present invention, the rear-wheel steering control system includes: an acquisition unit for acquiring the vehicle speed and the actual position angle and target position angle of the lead screw for controlling the rear-wheel steering; a processing unit for determining the difference between the actual position angle and the target position angle as the position angle deviation of the lead screw, and determining a first preset threshold value corresponding to the vehicle speed; and a control unit for controlling the rear wheel to return to the straight position according to the position angle deviation being greater than or equal to the first preset threshold value.

The rear-wheel steering control system according to the embodiment of the present invention has at least the following beneficial effects: the present invention can determine whether the rear-wheel steering is overshooting by judging whether the position angle deviation of the lead screw is greater than the first preset threshold value corresponding to the current vehicle speed, and the steering angle deviation of the rear wheel is judged by the position angle deviation of the lead screw with a relatively accurate result. When the position angle deviation of the lead screw is greater than the first preset threshold value, it indicates that the rear-wheel steering is overshooting. At this time, the rear wheel is controlled to return to the straight position by the rear-wheel steering system, which can be understood as returning the rear wheel to the zero position, thereby reducing the lateral force of the vehicle body and ensuring the functional safety of the entire vehicle.

According to an embodiment of the third aspect of the present invention, the rear-wheel steering control device comprises: at least one processor; at least one memory for storing at least one program; when the at least one program is executed by the at least one processor, the at least one processor implements the rear-wheel steering control method as described in the embodiment of the first aspect.

The rear-wheel steering control device according to the embodiment of the present invention has at least the above-mentioned beneficial effects, as its processor implements the rear-wheel steering control method of the above-mentioned embodiment, which will not be described in detail here.

The vehicle according to the fourth embodiment of the present invention comprises the rear-wheel steering control system of the second embodiment or the rear-wheel steering control device of the third embodiment.

The vehicle according to the embodiment of the present invention comprises the rear-wheel steering control system of the second aspect embodiment or the rear-wheel steering control device of the third aspect, and therefore has at least the above-mentioned beneficial effects, which will not be described in detail here.

According to the computer-readable storage medium of the fifth aspect embodiment of the present invention, processor-executable instructions are stored therein, and the processor-executable instructions are used to execute the rear-wheel steering control method of the first aspect embodiment when executed by the processor.

Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

FIG1 is a flowchart of the steps of a rear wheel steering control method according to some embodiments of the present invention;

FIG2 is a flowchart of the steps of a rear wheel steering control method according to some embodiments of the present invention;

FIG3 is a flowchart of the steps of a rear wheel steering control method according to some embodiments of the present invention;

FIG4 is a schematic diagram of the steering of the rear wheels in some embodiments of the present invention;

FIG5 is a schematic diagram of the steering of the rear wheels in some embodiments of the present invention;

FIG6 is a schematic diagram of a module of an active rear wheel steering control system function according to some embodiments of the present invention;

FIG7 is a graph showing the relationship between the speed and time of a lead screw in some embodiments of the present invention;

FIG8 is a flowchart of the function of the active rear wheel steering control system according to some embodiments of the present invention;

FIG9 is an example diagram of maximum tolerance values of rear wheel angle deviation corresponding to different vehicle speed ranges in some embodiments of the present invention;

FIG10 is a schematic diagram of a module of a rear wheel steering control system according to some embodiments of the present invention;

FIG. 11 is a schematic diagram of a module of a rear-wheel steering control device according to some embodiments of the present invention.

Reference numerals:

Rear wheel 100 , initial position 101 , current position 102 .

DETAILED DESCRIPTION

Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

Referring to FIG1 , a rear-wheel steering control method according to some embodiments of the present invention is shown, and the rear-wheel steering control method includes steps S100 and S200. The rear-wheel steering control method is applied to a vehicle having rear wheels and a rear-wheel steering system, and the rear-wheel steering system includes a motor and a lead screw, and the motor is used to drive the lead screw to rotate, and the lead screw converts the rotational motion output by the motor into linear motion, so that the lead screw drives the rear wheel to steer.

Among them, step S100: in response to the rear wheels starting to turn, the actual position angle of the screw and the target position angle of the screw are obtained, the difference between the actual position angle and the target position angle is determined as the position angle deviation of the screw, and the first preset threshold is obtained according to the vehicle speed.

In this step, when the driver turns the steering wheel, the steering wheel inputs a signal to the rear-wheel steering system, and the rear-wheel steering system can know that the rear wheel starts to turn at this time. The rear-wheel steering system calculates the target position angle of the lead screw according to the rotation amplitude of the steering wheel, and calculates the time when the motor needs to output power, and transmits power to the lead screw through the motor, thereby driving the lead screw to rotate, and the lead screw then drives the rear wheel to rotate. The actual position angle of the lead screw can be obtained according to the sensor on the lead screw, and then the position angle deviation of the lead screw can be obtained by subtracting the target position angle from the actual position angle. Since the lead screw drives the rear wheel to rotate, the position angle deviation of the lead screw can be understood as the steering angle deviation of the rear wheel. It should be noted that the position angle deviation of the lead screw is unexpected and changes with environmental factors. Then, the vehicle speed is obtained, and the first preset threshold is obtained according to the vehicle speed. It should be noted that for different vehicle speeds, the corresponding first preset thresholds are different. The greater the vehicle speed, the smaller the first preset threshold. At high speeds, the vehicle force is unstable and the safety risk is greater. Therefore, a higher steering angle deviation amount of the rear wheels is required. It can be understood that the vehicle speed is inversely proportional to the first preset threshold.

Step S200: When the position angle deviation is greater than or equal to a first preset threshold, the rear wheel steering system is controlled to return the rear wheels to the straight position.

In this step, when it is judged that the position angle deviation of the lead screw is greater than or equal to the first preset threshold value, it means that the position angle deviation of the lead screw exceeds the preset value, that is, the steering angle deviation of the rear wheel exceeds the preset value. It can be understood that the rear wheel steering system overshoots the rear wheel, mainly due to the influence of external road conditions, such as asphalt, cement, ice and other road surfaces, which easily cause the friction coefficient and external load of the rear wheel to change. At this time, the rear wheel steering system is controlled to slowly return the rear wheel to the correct position, which can also be understood as aligning the rear wheel and returning the rear wheel to the initial position. Specifically, the rear wheel steering system controls the motor to drive the lead screw to rotate in the opposite direction, and the rear wheel is driven by the lead screw to return to the correct position, which can reduce the lateral force generated by the rear wheel and ensure the functional safety of the whole vehicle. It should be noted that when the vehicle has a steering demand, since the front wheel can be turned normally, the rear wheel will not hinder the vehicle from turning even if it returns to the correct position. In this embodiment, it can be understood as entering the return to zero mode to return the rear wheel to zero.

It should be noted that in this embodiment, the steering angle deviation of the rear wheel is determined by the position angle deviation of the screw, and the result is relatively accurate. The steering angle of the rear wheel is affected by the deformation of the rubber bushing, etc., and the steering angle of the rear wheel obtained directly by the rear wheel angle sensor is not accurate enough.

4 and 5, in some embodiments, the position angle deviation of the lead screw is δ _si , the actual position angle of the lead screw is δ _sai , the target position angle of the lead screw is δ _sti , δ _si =δ _sai -δ _sti , δ _sai and δ _sti are both calculated from 0°, when the lead screw rotates to the position of δ _sai , the rear wheel 100 rotates by an angle θ ₁ , δ _sti is the position angle that the lead screw needs to reach, and it can also be understood that when the rear wheel 100 reaches the position of the target angle θ ₂ , the lead screw needs to rotate to the position corresponding to δ _sti . It should be noted that the rear wheel 100 has an initial position 101 and a current position 102. When the rear wheel 100 is at the initial position 101, the steering angle of the rear wheel 100 is 0, and the corresponding actual position angle δ _sai of the lead screw is also 0. When the screw controls the rear wheel 100 to start turning, the rear wheel 100 can swing from 0° to 90°, and the rear wheel 100 swings from the initial position 101 to the current position 102. When the rear wheel 100 reaches the current position 102, δ _sai is greater than 0.

Specifically, there are two situations in which the position of the lead screw deviates. The first situation is as shown in FIG4 , when δ _sai ＞δ _sti , δ _si ＞0, which can be understood as the rear wheel 100 turns beyond the target position, the rear wheel steering system overshoots the rear wheel, and the rear wheel 100 turns too far, and if δ _si is greater than the first preset threshold, it means that δ _si is too large, and the rear wheel steering system controls the motor to drive the lead screw to rotate in the opposite direction, and the lead screw drives the rear wheel 100 to swing in the direction of 0° until the rear wheel 100 returns to the initial position 101. As shown in FIG5 , when δ _sai ＜δ _sti , δ _si ＜0, which can be understood as the rear wheel steering system understeers the rear wheel 100, and the rear wheel 100 is not in place and is in a safe position. At this time, there is no need to return the rear wheel 100 to meet the vehicle steering requirements.

It can be understood that, as shown in FIG5 , when δ _sai ＜δ _sti and the rear wheel 100 has completed the steering, it means that the rear wheel 100 has not yet reached the correct position. If |δ _si | is greater than the first preset value, it means that the rear wheel 100 is far from the current position and the degree to which the rear wheel 100 has not yet reached the correct position is relatively large. At this time, the rear wheel 100 can be controlled to continue to reach the correct position. Based on this, in some embodiments, the rear wheel steering control method further includes step S300.

Specifically, as shown in FIG. 2 , step S300 : in response to the rear wheels completing steering, when the position angle deviation is less than zero and the absolute value of the position angle deviation is greater than a first preset threshold, the rear wheels are controlled to continue steering until the lead screw reaches the target position angle.

In this step, when the rear wheel completes the steering, it can also be understood that the rotation speed of the lead screw is 0, and the lead screw no longer drives the rear wheel to continue steering. At this time, if the absolute value of the position angle deviation of the lead screw |δ _si | is greater than the first preset value, the rear wheel can be controlled to continue steering, and the lead screw is rotated to the position of the target position angle, that is, the rear wheel is steered in place, so that the vehicle steering is more accurate. It should be noted that in this step, controlling the rear wheel to continue steering can be understood as the rear wheel starting to turn, and the system can respond to this, that is, after executing step S300, step S100 can be executed according to the response condition. If it is determined that the condition for executing step S300 is met, step S300 is executed again to allow the rear wheel to continue steering. If it is determined that the condition for executing step S200 is met, step S200 is executed.

In some embodiments, the first preset value is set to the maximum tolerance value δ _zmi of the angle deviation of the rear wheel. It should be noted that δ _zmi is obtained through CAE and actual vehicle calibration. For different speed intervals, the value of δ _zmi is different. If δ _si exceeds δ _zmi , it means that the rear wheel steering angle deviation is large, the lateral force on the whole vehicle is large, and driving is more dangerous. Specifically, as shown in FIG. 9, a plurality of speed intervals V _zi are divided within the commonly used speed range, and one speed interval V _zi corresponds to one δ _zmi . When the speed is higher, the value of δ _zmi is smaller, and the higher the speed, the larger the range covered by the speed interval V _zi .

It should be noted that, as shown in Figure 4, when δ _sai >δ _sti , δ _si >0, it can be understood that the rear wheel 100 turns beyond the target position, and the rear-wheel steering system overshoots the rear wheel. At this time, if δ _si is greater than δ _zmi , the motor is controlled to drive the lead screw to reverse. However, in the actual process, it takes a while for the motor to drive the lead screw to reverse and decelerate to 0, and the system also needs reaction time from receiving the deceleration instruction to starting to implement measures. This will cause the lead screw to continue to drive the rear wheel to turn during this period of time, causing δ _si to further increase, exceeding the range of δ _zmi . Therefore, it is necessary to give an advance amount when judging δ _si .

Based on this, in some embodiments, in step S200, according to the position angle deviation being greater than or equal to the first preset threshold, the step of controlling the rear wheels to return to the initial position specifically includes step S201 and step S202.

Specifically, as shown in FIG. 3 , step S201 : determining a second preset threshold according to the first preset threshold, where the second preset threshold is smaller than the first preset threshold.

In this step, since the second preset threshold is less than the first preset threshold, it can be understood that an advance amount is given, and by judging δ _si by the second preset value, the rear wheel can start to return to the correct position in advance. In some embodiments, the second preset threshold can be obtained by subtracting a constant value from the first preset threshold. The constant value can be selected by a large number of experiments or experience. The constant value cannot be too large or too small. A too large constant value causes the second preset threshold to be too small, which can easily trigger the rear wheel to return to the correct position by mistake. A too small constant value causes the second preset threshold to be too large, which causes the value of δ _si to exceed δ _zmi too much.

Step S202: When the position angle deviation is greater than or equal to a second preset threshold, the lead screw is controlled to decelerate to zero at a preset deceleration rate and rotate at a preset safety speed until the actual position angle of the lead screw is zero.

In this step, when it is determined that the position angle deviation δ _si is less than the second preset threshold, the rear wheel is controlled to return to the correct position. At this time, δ _si has not reached the first preset threshold δ _zmi , which is equivalent to controlling the lead screw to decelerate to 0 in advance, so as to avoid the lead screw driving the rear wheel to continue to turn and causing δ _si to exceed δ _zmi too much, which is equivalent to giving an advance amount, which can ensure timely control of the rear wheel to return to the correct position and ensure the safety of the whole vehicle. The preset deceleration and the preset safety speed can be selected according to the actual vehicle condition. In some embodiments, the preset deceleration and the preset safety speed can be selected according to the current vehicle speed. The greater the vehicle speed, the smaller the preset deceleration and the preset safety speed. In some embodiments, the preset safety speed can be less than the preset deceleration to avoid the rear wheel steering speed being too fast when the rear wheel returns to the correct position, so as to ensure the safety of the whole vehicle.

In some embodiments, the second preset threshold value can be calculated according to the deceleration characteristics of the rotation speed of the lead screw. Specifically, the first preset threshold value is the maximum tolerance value of the angle deviation of the rear wheel δ _zmi , the second preset threshold value is δ _smi , the preset rotation speed of the lead screw is V _si , the preset reaction time of the rear wheel steering system is t _f , and the preset deceleration of the lead screw is a _si , according to the formula: The numerical value of the second preset threshold δ _smi can be calculated.

It should be explained that, referring to FIG. 7 , which is a graph showing the relationship between the lead screw velocity V and time t, it can be understood as constituting a velocity function V(t): t→V, and the integral value of the velocity function V(t) in the interval [0, t ₀ ] is equal to the actual position angle δ _sai of the lead screw at time t ₀ , and it can also be understood that the area enclosed by the line segment of the lead screw velocity V and the time t axis is equal to the actual position angle δ _sai of the lead screw. The lead screw velocity V is the preset rotation speed of the lead screw, V _si . When the lead screw drives the rear wheel to turn, the lead screw rotates at a uniform speed, so the lead screw velocity V remains unchanged. Specifically, if the steering system overshoots the rear wheel, at a certain moment before _t1 , _δsi will be equal to 0. At _t1 , the system determines that _δsi is equal to _δsmi and _δsi is about to be greater than _δsmi . The system issues a deceleration control instruction to the motor. Since the system requires a certain response time, the system starts to control the motor to reverse at _t2 . It can be understood that _t2 is the moment when the system starts to take measures. In the above formula, _tf = _t1 - _t2 , _tf can be understood as the reaction time from the rear wheel steering system identifying and sending a deceleration signal to taking deceleration measures. _tf depends on the internal communication cycle and the controller hardware. _asi is obtained by combining the motor drive characteristics. In addition, in the above formula, It can be understood as the value of δ _smi obtained by subtracting δ _zmi . is equal to the integral value of the velocity function V(t) in the interval [t ₁ , t ₃ ], where t ₃ is the moment when the screw velocity V is equal to 0, which can be understood as, It is exactly equal to the area of the trapezoid enclosed by the line segment of the screw speed V from time _t1 to the time when the screw speed V is 0 and the time t axis. When the screw speed V decreases to 0, δ _{si is} exactly equal to δ _zmi .

For example, at a certain vehicle speed, δ _zmi = 4°, δ _smi = 3.5°, When it is detected that δ _si = δ _smi = 3.5°, the screw is controlled to decelerate to 0 at the preset deceleration a _si . During this process, since the screw speed V is not 0, δ _si will continue to increase. When the screw speed V decelerates to 0 at the preset deceleration a _si , the increment of δ _si is the trapezoidal area mentioned above, that is, Then δ _si will increase to 4°, which is exactly equal to δ _zmi . Therefore, in this embodiment, after δ _smi is obtained according to the above formula, δ _smi is used to judge δ _si . If, the degree of change of δ _si can be better controlled.

It should be noted that δ _smi and V _si are mutually adjusted quantities. If δ _smi is set too large, the system is robust, but V _si needs to be set small, which affects the system response speed; if δ _smi is set too small, V _si can be set large, making the system response speed fast, but the system is weak in robustness and easily affected by the environment. The two need to be balanced through actual vehicle calibration to ensure functional safety while achieving the best response speed and improve the competitiveness of the vehicle product.

Referring to FIG. 10 , a schematic diagram of a rear-wheel steering control system of some embodiments of the present invention is shown. The rear-wheel steering control system includes an acquisition unit, a processing unit, and a control unit. The acquisition unit is used to acquire the vehicle speed and the actual position angle and target position angle of the lead screw for controlling the rear-wheel steering. The processing unit is used to determine the difference between the actual position angle and the target position angle as the position angle deviation of the lead screw, and to determine the first preset threshold corresponding to the vehicle speed. The control unit is used to control the rear wheel to return to the positive position according to the position angle deviation being greater than or equal to the first preset threshold. Referring to FIG. 6 , the rear-wheel steering control system includes an ECU unit and an active rear-wheel steering actuator. The ECU unit can be understood as the above-mentioned processing unit, and the active rear-wheel steering actuator can be understood as the above-mentioned control unit. The ECU unit includes a comprehensive judgment module, which receives the input of the system hardware fault code signal G _d , the vehicle speed signal V _zi , the lead screw actual position angle signal δ _sai , the lead screw target position angle signal δ _sti , and the lead screw speed signal V _si , and makes a judgment.

Referring to FIG6 and FIG7 , a flowchart of the rear wheel steering control system of some embodiments of the present invention is shown. First, the start step S10 is executed, and then the step S20 is executed to obtain the vehicle status information. In step S30, it is identified whether the vehicle has a hardware fault. If there is no hardware fault, Gd=0. Then, the process proceeds to S40 for comprehensive judgment. When it is determined that δ _si ≥δ _smi , step S60 is executed to enter the zero return mode, that is, to return the rear wheel to the correct position. Specifically, it can be understood as executing the above step S200. When it is determined that δ _si ＜δ _smi , step S50 is executed to enter the normal mode, that is, to allow the rear wheel to steer normally without intervening the rear wheel.

An embodiment of the present invention also provides a rear-wheel steering control device, which includes at least one processor and at least one memory, where the memory is used to store at least one program. When the at least one program is executed by the at least one processor, the above-mentioned rear-wheel steering control method is implemented.

An embodiment of the present invention further provides a computer-readable storage medium, in which a computer program executable by a processor is stored. When the computer program executable by the processor is executed by the processor, it is used to implement the above-mentioned rear-wheel steering control method.

The embodiment of the present invention further provides a vehicle, comprising the rear wheel steering control system or the rear wheel steering control device of the above embodiment. Since the vehicle adopts the rear wheel steering control system or the rear wheel steering control device of the above embodiment, it has at least all the beneficial effects brought by the technical solution of the above embodiment, which will not be repeated here.

In some embodiments, the vehicle includes a front-wheel steering device, which provides steering wheel angle information, and the rear axle of the vehicle is equipped with a rear-wheel steering device that can perform follow-up steering according to the front wheel angle. The rear-wheel steering device generally includes an electronic control unit, a rear-wheel steering actuator, etc., and is also equipped with detection devices such as system hardware fault, vehicle speed, screw target position angle, screw actual position angle, screw speed, etc., and provides signals such as system hardware fault code, vehicle speed, screw target position angle, screw actual position angle, screw speed, etc.

Specifically, the vehicle may be a private car, such as a sedan, SUV, MPV or pickup truck. The vehicle may also be an operating vehicle, such as a van, bus, small truck or large trailer. The vehicle may be a gasoline vehicle or a new energy vehicle. When the vehicle is a new energy vehicle, it may be a hybrid vehicle or a pure electric vehicle.

In the description of the present invention, it is necessary to understand that descriptions involving orientation, such as orientation or positional relationship indicated as up, down, etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In the description of the present invention, "a plurality" means more than two. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

The terms "first", "second", "third", "fourth", etc. (if any) in the specification of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example. In addition, the terms "including" and "having" and any of their variations 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 necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

It should be understood that in the present application, "at least one (item)" means one or more, and "plurality" means two or more. "And/or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and/or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character "/" generally indicates that the objects associated before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, c can be single or multiple.

In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

In the embodiments of the present application, the term "module" or "unit" refers to a computer program or a part of a computer program with a predetermined function, and works together with other related parts to achieve a predetermined goal, and can be implemented in whole or in part by using software, hardware (such as processing circuits or memories) or a combination thereof. Similarly, a processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be part of an overall module or unit that includes the function of the module or unit.

The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, referred to as ROM), random access memory (Random Acce Memory, referred to as RAM), disk or optical disk and other media that can store program codes.

The step numbers in the above method embodiment are only provided for the convenience of explanation and description, and no limitation is imposed on the order of the steps. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

Claims (10)

1. A rear-wheel steering control method, characterized in that it is applied to a vehicle having a rear-wheel steering system, wherein the rear-wheel steering system comprises a lead screw for controlling the rear-wheel steering of the vehicle, and the rear-wheel steering control method comprises: In response to the rear wheel starting to turn, obtaining an actual position angle of the lead screw and a target position angle of the lead screw, determining a difference between the actual position angle and the target position angle as a position angle deviation of the lead screw, and obtaining a first preset threshold value according to a vehicle speed of the vehicle; When the position angle deviation is greater than or equal to the first preset threshold, the rear wheel steering system is controlled to return the rear wheel to the straight position. 2. The rear wheel steering control method according to claim 1, characterized in that the rear wheel steering control method further comprises the following steps: In response to the rear wheel completing the steering, when the position angle deviation is less than zero and the absolute value of the position angle deviation is greater than or equal to the first preset threshold, the rear wheel is controlled to continue steering until the lead screw reaches the target position angle. 3. The rear wheel steering control method according to claim 1, characterized in that the step of controlling the rear wheel to return to the normal position according to the position angle deviation being greater than or equal to the first preset threshold value comprises: Determine a second preset threshold according to the first preset threshold, wherein the second preset threshold is smaller than the first preset threshold; When the position angle deviation is greater than or equal to the second preset threshold, the lead screw is controlled to decelerate to zero at a preset deceleration speed and rotate at a preset safety speed until the actual position angle is zero. 4. The rear wheel steering control method according to claim 3, characterized in that the determining the second preset threshold according to the first preset threshold comprises: The second preset threshold is calculated using the following formula: The first preset threshold is the maximum tolerance value of the rear wheel angle deviation δ _zmi , the second preset threshold is δ _smi , the preset rotation speed of the screw is V _si , the preset reaction time of the rear wheel steering system is t _f , and the preset deceleration of the screw is a _si . 5 . The rear-wheel steering control method according to claim 3 , wherein the preset safety speed is smaller than the preset deceleration. 6 . The rear-wheel steering control method according to claim 1 , wherein the vehicle speed is inversely proportional to the first preset threshold. 7. A rear wheel steering control system, characterized by comprising: An acquisition unit, used for acquiring the vehicle speed and the actual position angle and target position angle of a lead screw for controlling rear wheel steering; a processing unit, configured to determine a difference between the actual position angle and the target position angle as a position angle deviation of the lead screw, and to determine a first preset threshold corresponding to the vehicle speed; A control unit is used to control the rear wheel to return to the straight position according to the position angle deviation being greater than or equal to the first preset threshold. 8. A rear wheel steering control device, comprising: at least one processor; at least one memory for storing at least one program; When the at least one program is executed by the at least one processor, the at least one processor implements the rear-wheel steering control method as described in any one of claims 1-6. 9. A computer-readable storage medium storing processor-executable instructions, wherein the processor-executable instructions are used to execute the rear-wheel steering control method according to any one of claims 1 to 6 when executed by the processor. 10. A vehicle, characterized by comprising the rear-wheel steering control system according to claim 7 or the rear-wheel steering control device according to claim 8.