Vehicle steering control method and apparatus, and storage medium

Abstract

A vehicle steering control method and apparatus, and a storage medium. The method comprises: in response to a vehicle steering instruction, controlling a first motor corresponding to a first rear wheel of a vehicle to output a first torque, and a second motor corresponding to a second rear wheel to output a second torque, wherein the first rear wheel is the rear wheel located on a steering side among two rear wheels of the vehicle, and the second rear wheel is the rear wheel located on a non-steering side of the vehicle.

Description

Vehicle steering control methods, devices and storage media

[0001] This application claims priority to Chinese patent application No. 202411523013.7, filed on October 29, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of vehicle technology, and in particular to a vehicle steering control method, device and storage medium. Background Technology

[0003] In related technologies, steering performance is one of the fundamental characteristics of a vehicle, and the key indicator for evaluating steering performance is the vehicle's turning radius. Currently, during a turn, both front and rear wheels of the vehicle rotate in the direction of the turn. Summary of the Invention

[0004] This disclosure provides a vehicle steering control method, apparatus, and storage medium that can reduce the turning radius of a vehicle. The vehicle steering control method provided in this disclosure can be applied to vehicles with distributed three motors, as well as vehicles with four-wheel independent drive or rear-wheel independent drive, to achieve on-the-spot steering functionality.

[0005] In a first aspect, a vehicle steering control method is provided, the method comprising: responding to a vehicle steering command, controlling a first motor corresponding to a first rear wheel of the vehicle to output a first torque and a second motor corresponding to a second rear wheel to output a second torque. The first torque has a reverse torque direction, the second torque has a forward torque direction, the first rear wheel is the rear wheel located on the steering side of the vehicle, and the second rear wheel is the rear wheel located on the non-steering side of the vehicle.

[0006] In some embodiments, in response to a vehicle steering command, controlling a first motor corresponding to a first rear wheel of the vehicle to output a first torque and a second motor corresponding to a second rear wheel to output a second torque includes: in response to a vehicle steering command, controlling the first motor corresponding to the first rear wheel to output the first torque to achieve rotation of the first rear wheel, and controlling the second motor corresponding to the second rear wheel to output the second torque to achieve forward rotation of the second rear wheel; the rotation of the first rear wheel includes forward rotation or reverse rotation.

[0007] In some embodiments, the first torque is determined by: obtaining a first actual slip ratio and a first target slip ratio of the first rear wheel; determining a first slip ratio difference and a first rate of change of the difference based on the first actual slip ratio and the first target slip ratio; the first slip ratio difference is the difference between the first target slip ratio and the first actual slip ratio, and the first rate of change of the difference is the rate of change of the first slip ratio difference per unit time; and determining the first torque based on the first slip ratio difference and the first rate of change of the difference.

[0008] In some embodiments, the first actual slip ratio is determined by: obtaining the rear axle center point velocity of the vehicle; determining the target wheel speed of the first rear wheel based on the rear axle center point velocity and the vehicle's yaw rate; and determining the actual slip ratio of the first rear wheel based on the target wheel speed and the actual wheel speed of the first rear wheel.

[0009] In some embodiments, the first target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio map, which indicates the target slip ratio corresponding to each of a plurality of candidate steering modes of the vehicle, wherein the steering mode is one of the plurality of candidate steering modes.

[0010] In some embodiments, determining the first torque based on the first slip ratio difference and the first rate of change of the difference includes: determining a first integral gain coefficient and a first proportional gain coefficient based on the first slip ratio difference and the first rate of change of the difference; and performing a proportional-integral (PI) operation on the first slip ratio difference based on the first integral gain coefficient and the first proportional gain coefficient to obtain the first torque.

[0011] In some embodiments, the second torque is determined by: obtaining a second target slip ratio and a second actual slip ratio of the second rear wheel; determining a second slip ratio difference and a second rate of change of the difference based on the second target slip ratio and the second actual slip ratio; the second slip ratio difference is the difference between the second target slip ratio and the second actual slip ratio, and the second rate of change of the difference is the rate of change of the second slip ratio difference per unit time; and determining the second torque based on the second slip ratio difference and the second rate of change of the difference.

[0012] In some embodiments, the second actual slip ratio is determined by: obtaining the rear axle center point speed of the vehicle; determining the target wheel speed of the second rear wheel based on the rear axle center point speed and the yaw rate of the vehicle; and determining the second actual slip ratio based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0013] In some embodiments, the second target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio map; the slip ratio map indicates the target slip ratio corresponding to each of a plurality of candidate steering modes of the vehicle, wherein the steering mode is one of the plurality of candidate steering modes.

[0014] In some embodiments, determining the second torque based on the second slip ratio difference and the second rate of change of the difference includes: determining a second integral gain coefficient and a second proportional gain coefficient based on the second slip ratio difference and the second rate of change of the difference; and performing a PI operation on the second slip ratio difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain the second torque.

[0015] In some embodiments, the multiple candidate steering modes include a spin turn mode and a non-spin turn mode. The non-spin turn mode includes a normal mode and a track mode. The target slip ratio corresponding to the normal mode is less than the target slip ratio of the track mode.

[0016] In some embodiments, the method further includes: when the vehicle is in a turnaround mode, in response to a vehicle steering command, controlling the braking of a first front wheel and the forward rotation of a second front wheel; the first front wheel is the front wheel on the steering side of the two front wheels of the vehicle, and the second front wheel is the other front wheel of the two front wheels of the vehicle besides the first front wheel.

[0017] In some embodiments, when the vehicle is in a turnaround mode, in response to a vehicle steering command, controlling the braking of the first front wheel and the forward rotation of the second front wheel includes: in response to a vehicle steering command, controlling the braking system of the first front wheel to apply braking force to the first front wheel to achieve braking of the first front wheel, and controlling the motor of the second front wheel to output a third torque to achieve forward rotation of the second front wheel.

[0018] Therefore, in the turn-around mode, the braking of the first front wheel, the forward rotation of the second front wheel, the reverse rotation of the first rear wheel, and the forward rotation of the second rear wheel are integrated, enabling the vehicle to turn around on the spot with a very small turning radius, and the vehicle can generate yaw moment while allowing users to experience a "drift" effect.

[0019] In some embodiments, the method further includes: when the vehicle is in a non-turn-around mode, controlling both the first and second front wheels of the vehicle to rotate in the forward direction in response to a vehicle steering command.

[0020] In some embodiments, when the vehicle is in a non-turn-around mode, in response to a vehicle steering command, controlling both the first and second front wheels of the vehicle to rotate in the forward direction includes: in response to a vehicle steering command, controlling the motors of the first and second front wheels to output a third torque to achieve both the first and second front wheels rotating in the forward direction.

[0021] In some embodiments, the method further includes: determining a third torque based on a first mapping relationship between the vehicle's accelerator pedal depth, motor speed, and the vehicle's steering mode. The first mapping relationship is a mapping relationship between the accelerator pedal depth, motor speed, and the third torque; different steering modes correspond to different first mapping relationships.

[0022] In some embodiments, the method further includes: displaying a steering mode setting interface, the steering mode setting interface including a plurality of candidate steering modes for the vehicle; and determining the vehicle's steering mode from the plurality of candidate steering modes in response to a user's setting operation on the steering mode setting interface.

[0023] In some embodiments, the method further includes: in response to vehicle operation, exiting a vehicle-activated steering mode and adjusting the vehicle's current torque at a torque adjustment rate; the torque adjustment rate is determined based on the current torque and the desired torque.

[0024] In some embodiments, the operation includes at least one of the following: vehicle speed greater than a preset threshold; brake pedal depth greater than a depth threshold; steering wheel speed greater than a speed threshold; deactivation of steering mode; rear wheel slip rate greater than a slip threshold; rear wheel slip change rate greater than a change threshold; gear shift; activation of electronic parking brake.

[0025] In a second aspect, a vehicle steering control device is provided, the device comprising: a processing component; the processing component being configured to, in response to a vehicle steering command, control a first motor corresponding to a first rear wheel of the vehicle to output a first torque and a second motor corresponding to a second rear wheel to output a second torque.

[0026] The first torque has a reverse torque direction, the second torque has a forward torque direction, the first rear wheel is the rear wheel on the steering side of the vehicle, and the second rear wheel is the rear wheel on the non-steering side of the vehicle.

[0027] Thirdly, a vehicle is provided, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the vehicle steering control method described above.

[0028] Fourthly, a computer-readable storage medium is provided, which stores instructions that, when executed on a terminal, cause the terminal to perform the vehicle steering control method described above.

[0029] Fifthly, a computer program product containing instructions is provided, which, when executed by a computer, causes the computer to perform the vehicle steering control method described above.

[0030] In a sixth aspect, a chip is provided, the chip including a processor and a communication interface, the communication interface and the processor being coupled, the processor being configured to run a computer program or instructions to implement the vehicle steering control method described above.

[0031] In some embodiments of this disclosure, the chip also includes a memory configured to store computer programs or instructions.

[0032] Based on the above technical solutions, the vehicle steering control method provided in some embodiments of this disclosure, the steering control system, in response to the vehicle steering command, controls the output torque of the first motor corresponding to the first rear wheel of the vehicle to be in the opposite direction and the output torque of the second motor corresponding to the second rear wheel to be in the positive direction, so that when the vehicle is turning, the rotational speed of the second rear wheel is higher than that of the first rear wheel, thereby creating a wheel speed difference between the two rear wheels. This wheel speed difference allows the vehicle to turn more flexibly, thereby reducing the turning radius. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 is a schematic diagram of a vehicle Ackerman turn according to some embodiments;

[0035] Figure 2 is an architecture diagram of a vehicle according to some embodiments;

[0036] Figure 3 is an architecture diagram of a steering control system according to some embodiments;

[0037] Figure 4 is a flowchart of a vehicle steering control method according to some embodiments;

[0038] Figure 5 is a scene diagram of a non-rotational turning mode according to some embodiments;

[0039] Figure 6 is a scene diagram of a rotation and turning mode according to some embodiments;

[0040] Figure 7 is a schematic diagram of the longitudinal force coefficient and lateral force coefficient under different slip rates according to some embodiments;

[0041] Figure 8 is a schematic diagram of a fuzzy PI control algorithm according to some embodiments;

[0042] Figure 9 is a flowchart of another vehicle steering control method according to some embodiments;

[0043] Figure 10 is a schematic diagram of a steering mode activation according to some embodiments;

[0044] Figure 11 is a schematic diagram of exiting a steering mode according to some embodiments;

[0045] Figure 12 is a schematic diagram of a vehicle steering control device according to some embodiments. Detailed Implementation

[0046] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0047] In the description of this disclosure, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or relative positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. Unless otherwise specified, the above-mentioned orientational descriptions can be flexibly set in practical applications, provided that the relative positional relationships shown in the accompanying drawings are satisfied.

[0048] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, unless otherwise stated, "a plurality of" means two or more.

[0049] In the description of this disclosure, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "communication" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. They can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0050] In embodiments of this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes that element.

[0051] In this disclosure, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or illustration. Any embodiment or design described as "exemplary" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments or designs. Rather, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0052] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0053] In related technologies, vehicle steering performance is one of its fundamental characteristics, and the key indicator for evaluating steering performance is the vehicle's turning radius. The minimum turning radius refers to the radius of the circle traced by the center of the outer steering wheel on the support surface when the steering wheel is turned to its limit and the vehicle is turning at its lowest stable speed.

[0054] For traditional vehicles, the minimum turning radius is mainly determined by the wheelbase and the maximum front wheel steering angle. Generally, once a vehicle's design is finalized, its minimum turning radius is also determined. The minimum turning radius also largely reflects a vehicle's ability to traverse narrow, winding areas or bypass obstacles that cannot be directly passed through.

[0055] As shown in Figure 1, during the current turning process, both the front and rear wheels of the vehicle rotate in the direction of the turn, which can easily affect the minimum turning radius of the vehicle and cause the turning radius R to be too large.

[0056] V L1 The speed of the front wheel on the turning side, V R1 V is the speed of the non-turning front wheel. L2 The speed of the rear wheel on the turning side, V R2 This refers to the speed of the rear wheel on the non-turning side.

[0057] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings.

[0058] As shown in Figure 2, some embodiments of this disclosure provide a vehicle 100, which may include a chassis 110, a body 120, and wheels 130. It is understood that the vehicle 100 may be a gasoline-powered vehicle, an electric vehicle, a hybrid vehicle, a natural gas vehicle, a methanol vehicle, a solar-powered vehicle, etc.

[0059] In some embodiments, vehicle 100 may be a passenger car such as a sedan, sport utility vehicle (SUV), or multi-purpose vehicle (MPV), or a bus, truck, or semi-trailer. This disclosure does not impose any limitations in this regard.

[0060] It is understood that the above-mentioned components are merely examples of some components of vehicle 100 and are not a limitation on the structure of vehicle 100.

[0061] In some embodiments, for the purpose of controlling the vehicle, the vehicle 100 may further include a steering control system 140. The steering control system 140 can realize steering control of the vehicle 100.

[0062] As shown in Figure 3, the steering control system of some embodiments of this disclosure may include: a steering system 210, a braking control system 220, a vehicle controller 230, a front wheel motor 240, and a rear wheel motor. The steering system 210, the braking control system 220, the front wheel motor 240, and the rear wheel motor are connected to the vehicle controller 230 via a controller area network (CAN).

[0063] In some embodiments, the vehicle controller 230 sends a vehicle steering command to the steering system 210, and the steering system 210 controls the first motor corresponding to the first rear wheel of the vehicle to output a first torque and the second motor corresponding to the second rear wheel to output a second torque.

[0064] The first torque has a reverse torque direction, the second torque has a forward torque direction, the first rear wheel is the rear wheel on the steering side of the vehicle, and the second rear wheel is the rear wheel on the non-steering side of the vehicle.

[0065] In some embodiments, the vehicle controller 230 can receive a driver's steering intention signal and send a vehicle steering command to the steering system 210, thereby controlling the rear wheel motor to output a first torque to achieve the rotation of the first rear wheel, and controlling the rear wheel motor to output a second torque to achieve the reverse rotation of the second rear wheel.

[0066] In some embodiments, the rotation of the first rear wheel includes forward rotation or reverse rotation.

[0067] In some embodiments, the rear wheel motor includes a first motor 250 corresponding to a first rear wheel and a second motor 260 corresponding to a second rear wheel.

[0068] In some embodiments, the vehicle controller 230 can receive the driver's steering intention signal. When the conditions for entering the steering function are met, the steering system 210 controls the first motor 250 corresponding to the first rear wheel to output a first torque to realize the rotation of the first rear wheel, and controls the second motor 260 corresponding to the second rear wheel to output a second torque to realize the forward rotation of the second rear wheel.

[0069] Similarly, the front wheel motor 240 can output torque to make the front wheel rotate.

[0070] In some embodiments, the vehicle controller 230 may, in response to a vehicle steering command, control the braking control system 220 to apply braking force to any one or more wheels of the vehicle.

[0071] In some embodiments, the steering control system 140 further includes a front axle differential 270, which is disposed on the front axle of the vehicle and mechanically connected to the front wheel motor 240.

[0072] The front axle differential 270 is configured to adjust the speed difference between the inner and outer drive wheels when the vehicle is turning, ensuring that the outer wheels can rotate at a higher speed than the inner wheels, thereby improving the vehicle's cornering performance.

[0073] In some embodiments, the steering control system 140 further includes a wheel speed sensor 280, which is connected to the vehicle controller 230 via a CAN network. The wheel speed sensor 280 is configured to measure the rotational speed of the wheels of the vehicle during driving, i.e., wheel speed information, and send the wheel speed information of the four wheels of the vehicle to the vehicle controller 230.

[0074] Each of the vehicle's wheels corresponds to a wheel speed sensor 280.

[0075] In some embodiments, the steering control system 140 further includes a yaw rate sensor 290, which is connected to the vehicle controller 230 via a CAN network. The yaw rate sensor 290 is configured to monitor the vehicle's trajectory about its vertical axis (i.e., longitudinal axis) to determine whether the vehicle is slipping or out of control, and to send yaw information of the vehicle to the vehicle controller 230.

[0076] It should be noted that the control system described in this disclosure is for the purpose of more clearly illustrating the technical solutions of this disclosure, and does not constitute a limitation on the technical solutions provided in this disclosure. Those skilled in the art will understand that with the evolution of electronic devices and the emergence of other electronic devices, the technical solutions provided in this disclosure are also applicable to similar technical problems. The methods in the following embodiments can all be implemented in a control system having the above-described hardware structure.

[0077] The methods described in the following embodiments can all be implemented in a control system with the above-described hardware structure.

[0078] The vehicle steering control method provided by some embodiments of this disclosure will be described in detail below with reference to the accompanying drawings.

[0079] The vehicle steering control method of some embodiments disclosed herein can be applied to the steering control of a vehicle. As shown in FIG4, the vehicle steering control method may include steps 301-302. Step 301 may also be referred to as the "acquiring vehicle steering command" process, and step 302 may be referred to as the "performing vehicle steering control" process. Steps 301-302 are described in detail below.

[0080] Step 301: Obtain vehicle steering commands.

[0081] In some embodiments, the vehicle steering command includes at least a first rear wheel rotation command and a second rear wheel rotation command. The first rear wheel is the rear wheel on the steering side of the vehicle, and the second rear wheel is the rear wheel on the non-steering side of the vehicle. The first rear wheel may be referred to as the inner rear wheel, and the second rear wheel may be referred to as the outer rear wheel; this disclosure does not limit the scope of the application.

[0082] In some embodiments, the vehicle steering command may further include a first front wheel and a second front wheel forward rotation command, or a first front wheel braking command and a second front wheel forward rotation command. The first front wheel is the front wheel on the steering side of the vehicle's two front wheels, and the second front wheel is the other front wheel of the vehicle besides the first front wheel.

[0083] Step 302: In response to the vehicle steering command, control the first motor corresponding to the first rear wheel of the vehicle to output the first torque and the second motor corresponding to the second rear wheel to output the second torque.

[0084] The first torque has a reverse torque direction, while the second torque has a forward torque direction.

[0085] In one possible implementation, in response to a vehicle steering command, the steering control system controls a first motor corresponding to the first rear wheel to output a first torque to achieve rotation of the first rear wheel, and controls a second motor corresponding to the second rear wheel to output a second torque to achieve forward rotation of the second rear wheel. The rotation of the first rear wheel can be either forward or reverse.

[0086] Understandably, when a vehicle turns, in addition to the steering force and direction of the front wheels, the rear-wheel steering system can also cause the rear wheels to have a steering angle. By controlling the motor output torque of the inner rear wheel to be in the opposite direction (first torque), it helps to reduce the rotational speed of the inner rear wheel. Conversely, by controlling the motor output torque of the outer rear wheel to be in the positive direction (second torque), it helps to increase the rotational speed of the outer wheel, thereby applying a yaw moment to the vehicle in the same direction as the steering direction, allowing the wheels to turn with a smaller turning radius.

[0087] Furthermore, the counter-rotation of the inner rear wheel reduces its rotational speed, making it easier for the vehicle to lean inwards. Conversely, the forward rotation of the outer rear wheel increases its rotational speed and friction, applying a yaw moment in the same direction as the steering. Combined, these factors allow the vehicle to stay more closely around its center point when cornering, thus reducing its turning radius.

[0088] This disclosure provides embodiments of a vehicle with multiple candidate steering modes, such as a U-turn mode and a non-U-turn mode. The U-turn mode is used for rapid U-turns on narrow roads. The non-U-turn mode includes at least one of the following: a normal mode and a track mode. The normal mode can be used as the vehicle's default operating mode, which can reduce tire wear and increase vehicle ride smoothness. The track mode allows the vehicle to quickly navigate U-turns by adjusting the motor's torque output, thereby reducing cornering time.

[0089] In some embodiments, when the vehicle is in a non-turn-around mode, the steering control system responds to the vehicle steering command by controlling both the first and second front wheels of the vehicle to turn in the forward direction.

[0090] As shown in Figure 5, when the vehicle is in normal mode or track mode, the steering control system responds to the forward rotation commands of the first and second front wheels by controlling the motors of the first and second front wheels to output a third torque to achieve forward rotation of both the first and second front wheels. Furthermore, responding to the rotation commands of the first and second rear wheels and the forward rotation commands of the second rear wheels, the system controls the first motor corresponding to the first rear wheel to output a first torque to achieve rotation of the first rear wheel, and controls the second motor corresponding to the second rear wheel to output a second torque to achieve forward rotation of the second rear wheel. Here, the rotation of the first rear wheel can be either forward or reverse; this disclosure does not limit this.

[0091] Understandably, the steering control system responds to vehicle steering commands by controlling the output torque of the first motor of the first rear wheel to be in the opposite direction to achieve rotation of the first rear wheel, and controlling the output torque of the second motor of the second rear wheel to be in the positive direction to achieve rotation of the second rear wheel. This results in the second rear wheel rotating at a higher speed than the first rear wheel when the vehicle is turning, thereby creating a wheel speed difference between the two rear wheels. This wheel speed difference allows the vehicle to steer more flexibly, thus reducing the turning radius.

[0092] Understandably, the torque output by the motor in normal mode and track mode is different, thus achieving different steering effects. Furthermore, the target slip ratio in normal mode is lower than that in track mode.

[0093] In some embodiments, when the vehicle is in a turnaround mode, the steering control system responds to the vehicle steering command by controlling the braking of the first front wheel and the forward rotation of the second front wheel.

[0094] As shown in Figure 6, in response to a first front wheel braking command, the steering control system controls the braking system of the first front wheel to apply braking force to the first front wheel to brake it. In response to a second front wheel forward rotation command, the system controls the motor of the second front wheel to output a third torque to make the second front wheel rotate forward. In response to a first rear wheel rotation command and a second rear wheel forward rotation command, the system controls the first motor corresponding to the first rear wheel to output a first torque to achieve the rotation of the first rear wheel, and controls the second motor corresponding to the second rear wheel to output a second torque to achieve the forward rotation of the second rear wheel.

[0095] It should be noted that in the spin-turn mode, if the first rear wheel rotates in the opposite direction, the turning radius of the vehicle can be reduced.

[0096] The braking force applied to the first front wheel is directly proportional to the depth of the accelerator pedal. By applying braking force to the first front wheel, the torque of the front wheel motor can be provided to the second front wheel as much as possible, thereby increasing the yaw gain when the vehicle is turning. In addition, when the braking force of the first front wheel reaches the braking force threshold, the first front wheel can be controlled to roll with a certain slip ratio to avoid wheel wear.

[0097] Understandably, applying braking force to the front wheels on the steering side causes the vehicle to decelerate during a turn, creating a force that pulls the vehicle inwards towards the curve. This inward force helps the vehicle stay closer to the turn. In other words, when braking is applied to the front wheels on the steering side, because those wheels have a larger steering angle and lower speed, the vehicle is more inclined to turn around those front wheels (i.e., the static steering center point), thus reducing the turning radius. Combined with the first rear wheel rotating in the opposite direction and the second rear wheel rotating in the forward direction, this further helps to reduce the vehicle's turning radius.

[0098] The above provides a detailed overview of how to perform vehicle steering control. The following section details how to calculate the first torque of the first rear wheel, the second torque of the second rear wheel, and the third torque of the second front wheel.

[0099] In one possible implementation, the first torque of the first rear wheel can be determined by: obtaining the first actual slip ratio and the first target slip ratio of the first rear wheel, and determining the first slip ratio difference and the first rate of change of the difference based on the first actual slip ratio and the first target slip ratio, and then determining the first torque based on the first slip ratio difference and the first rate of change of the difference.

[0100] The first slip ratio difference is the difference between the first target slip ratio and the first actual slip ratio, and the first difference change rate is the rate of change of the first slip ratio difference per unit time. Slip ratio refers to the proportion of wheel slip in the longitudinal motion of the wheel.

[0101] It should be noted that the first target slip ratio can be determined based on the vehicle's steering mode and a pre-calibrated slip ratio mapping table. The slip ratio mapping table indicates the target slip ratio corresponding to each of the vehicle's multiple candidate steering modes. In other words, the first target slip ratio of the first rear wheel can be obtained based on the vehicle's steering mode. For example, when the vehicle is in normal mode, the first target slip ratio of the first rear wheel can be obtained from the slip ratio mapping table corresponding to that mode. Similarly, when the vehicle is in track mode or spin-around mode, the corresponding slip ratio mapping table can be obtained, and thus the target slip ratio can be derived.

[0102] Understandably, users can select a steering mode that suits their driving habits based on their needs. The steering control system can then obtain the corresponding slip ratio mapping table based on the selected steering mode to determine the first target slip ratio for the first rear wheel. The degree to which different steering modes reduce the vehicle's turning radius can be ranked as follows: Normal mode < Track mode < U-turn mode. That is, the U-turn mode has the greatest effect on reducing the turning radius, followed by Track mode, and finally Normal mode.

[0103] In some embodiments, as shown in Figure 7, the rear wheels of a vehicle do indeed slip or spin to a certain extent when turning in order to effectively reduce the vehicle's turning radius. However, when the driving force of the tires reaches its limit, the longitudinal adhesion of the tires will decrease significantly, leading to a decrease in vehicle stability. Therefore, during the control process, the output torque of the rear wheels must be precisely controlled to prevent the rear wheels from over-spinning (i.e., flying).

[0104] It is understandable that when the vehicle is traveling in a straight line or turning at a small steering angle, the formulas for calculating the wheel slip ratio S and the slip ratio St can be the following formulas 1 and 2.

[0105] Where v is the vehicle speed, w r Let ω be the angular velocity of the wheel, and r be the rolling radius of the wheel.

[0106] In conventional vehicle speed estimation, the average wheel speed of the two non-driving front wheels or the two non-driving rear wheels is usually used to approximate the vehicle speed. However, this method becomes inaccurate when the vehicle turns at a large steering angle. This is because the wheel speed of the inner wheel is lower than that of the outer wheel, and the wheel speed of the front wheels is generally higher than that of the rear wheels. If the slip ratio S and the turning ratio S are still calculated using the above formulas 1 and 2 in this situation... t This will lead to inaccurate results, thereby weakening the performance of the steering control system. Therefore, some embodiments of this disclosure provide a method for obtaining the first actual slip ratio, as shown below.

[0107] In some embodiments, the first actual slip ratio can be determined by: obtaining the rear axle center point speed of the vehicle, and determining the target wheel speed of the first rear wheel based on the rear axle center point speed and the yaw rate of the vehicle, and then determining the first actual slip ratio based on the target wheel speed of the first rear wheel and the actual wheel speed of the first rear wheel.

[0108] It should be noted that when both front wheels are rotating in the same direction, the speed of the rear axle center point is determined based on the speed of the front axle center point. When the first front wheel is braking and the second front wheel is rotating in the same direction, the speed of the rear axle center point is determined based on the actual wheel speed of the second front wheel.

[0109] In some embodiments, as shown in Figure 1, when the vehicle is turning, the following can be obtained from the monorail bicycle model: Simplifying this formula yields Formula 3 for the vehicle's turning radius R.

[0110] Wherein, the average front wheel steering angle δ=(δ1+δ2) / 2, δ1 is the left front wheel steering angle, δ2 is the right front wheel steering angle, L is the vehicle wheelbase, b is the distance from the center of gravity to the rear axle, and B is the vehicle track width.

[0111] Based on the vehicle dynamics characteristics, the yaw rate of all points on the vehicle is equal, which leads to the following formula 4.

[0112] Where V1 is the velocity at the center point of the front axle, V2 is the velocity at the center point of the rear axle, and V R1 This represents the theoretical wheel speed of the right front wheel.

[0113] The rear axle center point velocity V2 can be obtained using Formula 4 above. Then, the theoretical wheel speeds of the left and right rear wheels can be calculated using Formulas 5 and 6 below. L2 =V² + Bw / 2 (Formula 5) R2 =V² - Bw / 2 (Formula 6)

[0114] Among them, V L2 V is the theoretical wheel speed of the left rear wheel. R2 ω is the theoretical wheel speed of the right rear wheel, and w is the yaw rate of the vehicle.

[0115] After calculating and determining the theoretical wheel speed of the rear wheel, the slip ratio or slip rate of the rear wheel can be determined based on the theoretical wheel speed and the actual wheel speed, as shown in Formulas 7 and 8 below.

[0116] Where S is the slip ratio, T is the slip coefficient, Vv is the theoretical wheel speed, and Vw is the actual wheel speed.

[0117] In some embodiments, as shown in Figure 5, the vehicle is in a non-rotational U-turn mode. At this time, the motor outputs a first torque in the opposite direction, causing the first rear wheel to rotate; the motor outputs a second torque in the positive direction, causing the second rear wheel to rotate in the forward direction, and causing both front wheels to rotate in the forward direction towards the steering side. Since the two front wheels have no slip ratio, the wheel speeds of the two front wheels can be approximated as the front axle center point speed V1, which is obtained using the following formula 9.

[0118] Where Vl1 is the actual wheel speed of the first front wheel, Vr1 is the actual wheel speed of the second front wheel, and δ2 is the turning angle of the outer front wheel.

[0119] Substituting Formula 9 into Formula 10 below, we obtain the rear axle center point velocity V2. In other words, the rear axle center point velocity V2 is calculated based on the front axle center point velocity V1.

[0120] Substituting the rear axle center point velocity V2 and the vehicle's yaw rate w into Equations 11 and 12 below, the slip ratio S of the first rear wheel is obtained. L2 slip ratio T of the second rear wheel R2 .

[0121] Where V2-Bw / 2 is the target wheel speed (i.e., theoretical wheel speed) of the first rear wheel, which can be understood as Vv in formula 7 or formula 8; Vl2 is the actual wheel speed of the first rear wheel, which can be understood as Vw in formula 7 or formula 8 above.

[0122] In some embodiments, the steering control system may determine a first integral gain coefficient and a first proportional gain coefficient based on a first slip ratio difference and a first rate of change of the difference, and perform a proportional-integral (PI) operation on the first slip ratio difference based on the first integral gain coefficient and the first proportional gain coefficient to obtain a first torque.

[0123] As shown in Figure 8, based on the first target slip ratio and the first actual slip ratio, the first slip ratio difference and the first difference change rate are determined. The first slip ratio difference and the first difference change rate are input into the PI fuzzy rule table to obtain the adaptively changing proportional gain coefficient Kp and integral gain coefficient Ki. Then, the proportional gain coefficient Kp and integral gain coefficient Ki are input into the PI control system to determine the first torque of the first rear wheel.

[0124] As shown in Table 1 and Table 2 below, the PI fuzzy rule table includes the Kp fuzzy rule table and the Ki fuzzy rule table.

[0125] Table 1. Kp Fuzzy Rule Table

[0126] Table 2 Ki Fuzzy Rule Table

[0127] In Tables 1 and 2 above, NL represents negative large, NM represents negative medium, NS represents negative small, ZE represents zero, PS represents positive small, PM represents positive medium, and PL represents positive large.

[0128] For example, the proportional gain coefficient Kp and integral gain coefficient Ki of the first rear wheel can be determined by using a two-dimensional lookup table based on the first difference change rate EC and the first slip ratio difference E.

[0129] Taking a first difference rate of change EC of 0% and a first slip ratio difference E of 0.2 as an example, firstly, we look at the Kp fuzzy rule table. Since the first difference rate of change EC is 0%, we can determine the fuzzy value of the first difference rate of change EC as ZE. Since the first slip ratio difference E is 0.2, we can determine the fuzzy value of the first slip ratio difference E as PS. Combining ZE and PS, we can obtain the proportional gain coefficient Kp as NS and the integral gain coefficient Ki as ZE. Then, we input the proportional gain coefficient Kp (NS) and the integral gain coefficient Ki (ZE) into the PI control system to obtain the first torque of the first rear wheel.

[0130] In some embodiments, when the steering control system is in the initial stage, the first slip ratio difference E is relatively large. By using the two-dimensional lookup table method described above, a larger proportional gain coefficient Kp and a smaller integral gain coefficient Ki can be obtained to improve the system's response speed.

[0131] When the steering control system is in the pre-stabilization stage, the first slip ratio difference E is within the preset range, and the slip ratio of the steering control is near the target value. At this time, the proportional gain coefficient Kp and the integral gain coefficient Ki can be kept at appropriate values.

[0132] When the steering control system is in a stable phase, the first slip ratio difference E is very small. In order to improve the system robustness and response speed, the proportional gain coefficient Kp and integral gain coefficient Ki can be appropriately increased.

[0133] In one possible implementation, the second torque of the second rear wheel can be determined by: obtaining the second target slip ratio and the second actual slip ratio corresponding to the second rear wheel, and determining the second slip ratio difference and the second difference change rate based on the second target slip ratio and the second actual slip ratio, and then determining the second torque based on the second slip ratio difference and the second difference change rate.

[0134] The second slip ratio difference is the difference between the second target slip ratio and the second actual slip ratio, and the rate of change of the second slip ratio difference is the rate of change of the second slip ratio difference per unit time. Slip ratio refers to the degree to which a wheel slips during driving.

[0135] It should be noted that the second target slip ratio can be determined based on the vehicle's steering mode and a pre-calibrated slip ratio mapping table. The slip ratio mapping table indicates the target slip ratio corresponding to each of the vehicle's multiple candidate steering modes. In other words, the second target slip ratio of the second rear wheels can be obtained based on the vehicle's steering mode. For example, when the vehicle is in normal mode, the second target slip ratio of the second rear wheels can be obtained from the slip ratio mapping table corresponding to that mode. Similarly, when the vehicle is in track mode or spin-around mode, the corresponding slip ratio mapping table can be obtained, and thus the target slip ratio can be derived.

[0136] In some embodiments, the second actual slip ratio is determined by: obtaining the rear axle center point speed of the vehicle, and determining the target wheel speed of the second rear wheel based on the rear axle center point speed and the yaw rate of the vehicle, and then determining the second actual slip ratio based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0137] As shown in Figure 6, the vehicle is in a U-turn mode. At this time, the motor outputs a first torque in the opposite direction, causing the first rear wheel to rotate. The motor outputs a second torque in the forward direction, causing the second rear wheel to rotate in the forward direction. This also applies braking force to the first front wheel and a third torque to the second front wheel. Since the first front wheel (i.e., the front wheel on the steering side) is in a braking state, the rear axle center point speed V2 can be calculated based on the actual wheel speed of the second front wheel, as shown in Formula 13 below.

[0138] Furthermore, the rear axle center point velocity V2 obtained above can be substituted into formulas 11 and 12 above to obtain the slip ratio S of the first rear wheel. L2 slip ratio T of the second rear wheel R2 .

[0139] In some embodiments, the actual wheel speeds of the aforementioned wheels are obtained through wheel speed sensors installed on the wheels. However, when the vehicle is in non-U-turn mode or U-turn mode, the wheel speeds may be low. In this case, the wheel speeds collected by the wheel speed sensors have problems such as low accuracy and slow update speed. Therefore, the wheel speed obtained from the motor speed and the wheel speed collected by the wheel speed sensors can be weighted and then the wheel slip ratio or slip rate can be calculated. The wheel speed Vw calculated from the motor speed w is shown in Formula 14 below.

[0140] Where r is the rolling radius of the wheel, and rat is the transmission ratio of the motor.

[0141] In some embodiments, the steering control system determines a second integral gain coefficient and a second proportional gain coefficient based on a second slip ratio difference and a second rate of change of the difference, and performs a PI calculation on the second slip ratio difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain a second torque.

[0142] Based on the second target slip ratio and the second actual slip ratio, the second slip ratio difference and the second difference change rate are determined. The second slip ratio difference and the second difference change rate are input into the PI fuzzy rule table to obtain the adaptive proportional gain coefficient Kp and integral gain coefficient Ki. Then, the proportional gain coefficient Kp and integral gain coefficient Ki are input into the PI control system to determine the second torque of the second rear wheel.

[0143] For example, the steering control system can use a two-dimensional lookup table based on the second differential change rate EC and the second slip rate difference E to determine the proportional gain coefficient Kp and integral gain coefficient Ki of the second rear wheel. It is understood that the determination method for the proportional gain coefficient Kp and integral gain coefficient Ki of the second rear wheel is the same as that for the first rear wheel, and will not be elaborated upon here.

[0144] In some embodiments of this disclosure, an adaptive fuzzy PI control algorithm is used to control the wheel slip rate (or slip ratio) near the desired slip rate. This disclosure does not limit the PI control algorithm, and other control algorithms may also be used.

[0145] It should be noted that the slip ratio or slip rate mentioned in some embodiments of this disclosure can also be replaced by wheel speed, and this disclosure does not limit this.

[0146] In one possible implementation, the third torque of the second front wheel can be determined based on the vehicle's accelerator pedal depth, motor speed, and vehicle steering mode.

[0147] In some embodiments, the steering control system may determine the third torque based on a first mapping relationship between the vehicle's accelerator pedal depth, motor speed, and the vehicle's steering mode.

[0148] The first mapping relationship is the mapping relationship between accelerator pedal depth, motor speed, and third torque. Different steering modes correspond to different first mapping relationships.

[0149] Based on the vehicle's current steering mode, the corresponding weighted acceleration curve (i.e., the first mapping relationship) is determined, and then the corresponding third torque is obtained from the weighted acceleration curve based on the accelerator pedal depth and motor speed.

[0150] In some embodiments, the driver can control the torque output of the motor by adjusting the depth of the accelerator pedal, thereby controlling the vehicle speed.

[0151] The above provides a detailed explanation of how to calculate the first torque of the first rear wheel, the second torque of the second rear wheel, and the third torque of the second front wheel.

[0152] It is understood that the vehicle steering control method provided in some embodiments of this disclosure can be applied to vehicles with distributed three motors, as well as vehicles with four-wheel independent drive or rear-wheel independent drive, to achieve the function of turning in place.

[0153] Based on the above technical solution, the steering control system responds to the vehicle's steering command by controlling the motor output torque of the first rear wheel to be a first torque in the opposite direction, and the motor output torque of the second rear wheel to be a second torque in the positive direction. This makes the rotational speed of the second rear wheel higher than that of the first rear wheel when the vehicle is turning, thereby creating a wheel speed difference between the two rear wheels. This wheel speed difference allows the vehicle to turn more flexibly, thereby reducing the turning radius.

[0154] As shown in Figure 9, some embodiments of this disclosure also provide another vehicle steering control method, which includes the following steps 901-905.

[0155] Step 901: Display the steering mode settings interface.

[0156] The steering mode settings interface includes multiple candidate steering modes for the vehicle, including normal mode, track mode, and spin-around mode.

[0157] Normal mode can be used as a regular function. This mode can reduce tire wear and increase the smoothness of vehicle driving. In this mode, the slip ratio of the first rear wheel and the slip ratio of the second rear wheel are both controlled within 10%, the tire wear is within an acceptable range, and the turning radius can be reduced by about 12%.

[0158] Track mode can be used to quickly navigate U-turns, thereby reducing cornering time. Understandably, when the conditions for entering track racing mode are met, the system can determine the vehicle's current state based on signals such as speed, steering wheel angle, and yaw rate, and adjust the torque output of the front and rear motors in real time to reduce cornering time.

[0159] The U-turn mode can be used to turn vehicles around in narrow roads. When the conditions for entering the U-turn mode are met, turn the steering wheel fully clockwise (or counterclockwise) and simultaneously, when the accelerator pedal depth is greater than the set threshold, the quick U-turn function is activated. By applying braking force to the first front wheel (the front wheel on the steering direction side) and controlling the motor output torque of the first rear wheel to be in the opposite direction (first torque) and the motor output torque of the second rear wheel to be in the positive direction (second torque), the vehicle generates a lateral torque in the steering direction, thus achieving a quick U-turn.

[0160] In some embodiments, the vehicle's central control display screen can show multiple candidate steering modes for the user to select. The driver can select different candidate steering modes by touching physical buttons or virtual buttons.

[0161] Step 902: In response to the user's setting operation on the steering mode setting interface, determine the vehicle's steering mode from multiple candidate steering modes.

[0162] In some embodiments, users can view multiple candidate steering modes displayed on the central control screen and select the desired steering mode according to their needs. The vehicle can determine the steering mode in response to the user's settings.

[0163] Step 903: Based on the vehicle's operating status, determine whether to activate the vehicle's steering mode.

[0164] The vehicle's operating status includes at least one of the following: driving status, curve status, and exiting curve status.

[0165] The vehicle's operating state can be determined based on the vehicle's motion parameters, which include at least one of the following: accelerator pedal depth, brake pedal depth, steering wheel angle, yaw rate, sideslip angle, sideslip acceleration, lateral acceleration, and longitudinal acceleration.

[0166] In some embodiments, as shown in FIG10, the steering control system can input the accelerator pedal depth, brake pedal depth, steering wheel angle, yaw rate, center of gravity sideslip angle, center of gravity sideslip angle acceleration, lateral acceleration, and longitudinal acceleration into the state recognition component to determine the current operating state of the vehicle.

[0167] Furthermore, when the vehicle's operating state changes from driving to entering a curve, the vehicle's steering mode is activated.

[0168] In some embodiments, when the user selects the normal mode for the vehicle steering and the vehicle is idling, it is determined whether the steering wheel angle is greater than a first steering angle threshold. If it is greater, the vehicle's operating state is determined to change from driving state to cornering state, thereby activating the normal mode.

[0169] In some embodiments, when the user selects track mode as the vehicle steering mode, it is determined whether the vehicle speed is greater than a speed threshold and whether the steering wheel angle is greater than a steering angle threshold. If both are greater, the vehicle's operating state is determined to change from driving state to cornering state, thereby activating track mode.

[0170] In some embodiments, determining whether to activate the track mode can further involve determining whether the accelerator pedal depth is greater than a threshold and whether the self-slip angle is greater than an angle threshold (the angle between the vehicle's direction of movement and the steering wheel). If the vehicle speed is greater than a speed threshold, the steering wheel angle is greater than an angle threshold, the accelerator pedal depth is greater than a threshold, and the self-slip angle is greater than an angle threshold, the track mode is activated.

[0171] In some embodiments, when the user selects the vehicle steering mode as the turn-around mode, it is determined whether the steering wheel angle is greater than the second steering angle threshold, i.e., whether the steering wheel is turned to the full position. If it is greater, the track mode is activated.

[0172] Step 904: In response to the vehicle steering command, control the first motor corresponding to the first rear wheel of the vehicle to output the first torque and the second motor corresponding to the second rear wheel to output the second torque.

[0173] Step 904 can refer to the implementation method shown in step 302 above. It will not be described again here.

[0174] Step 905: In response to the vehicle's operation, exit the vehicle's steering mode and adjust the vehicle's current torque at the torque adjustment rate.

[0175] In some embodiments, as shown in FIG11, the steering control system inputs the current vehicle speed, rear wheel slip ratio, rear wheel spin ratio, slip change rate, spin change rate, brake pedal depth, steering wheel speed, gear change status, and electronic parking brake status into the status recognition component to determine the current operating status of the vehicle.

[0176] Furthermore, when the vehicle's operating state changes from a curve state to an exit curve state, it reverts to the vehicle's activated steering mode and adjusts the vehicle's current torque according to the torque adjustment rate.

[0177] The operation includes at least one of the following: vehicle speed exceeding a preset threshold, brake pedal depth exceeding a depth threshold, steering wheel speed exceeding a speed threshold, gear shift, electronic parking brake activation, user-activated steering mode, rear wheel slip ratio exceeding a slip threshold, and rear wheel slip change rate exceeding a change threshold. The rear wheel slip ratio may include the slip ratio of the first rear wheel and the slip ratio of the second rear wheel, and the corresponding rear wheel slip change rate may include the slip change rate of the first rear wheel and the slip change rate of the second rear wheel.

[0178] For example, when the vehicle meets any two or more of the above operating conditions, indicating that the vehicle is transitioning from a curve exit state, the vehicle exits the activated steering mode and adjusts the vehicle's current torque to the driver's desired torque using the torque adjustment rate. For example, if significant changes in road adhesion cause the actual slip ratio of the first rear wheel or the actual slip ratio of the second rear wheel to exceed the corresponding threshold, or their rate of change to exceed the change threshold, the steering control system exits the activated steering mode.

[0179] It should be noted that the torque adjustment rate is determined by looking up a table based on the difference between the current torque and the required torque. Understandably, when the steering mode is disengaged or when wheel slip or rotation becomes uncontrollable, adjusting the vehicle's current torque through the torque adjustment rate can smooth the vehicle's output torque, reduce the jerking sensation caused by torque changes, and improve the driver's driving experience.

[0180] In some embodiments, when a user turns off the steering mode, the user can exit the steering mode by displaying a large screen, using physical buttons, or through a voice assistant.

[0181] In some embodiments, the vehicle's infotainment system and instrument panel may display a message such as "Mode Exited" to inform the user of the vehicle's current status.

[0182] Based on the above technical solutions, the steering control method provided in some embodiments of this disclosure allows users to select different steering modes according to the usage scenario, and determines whether to activate the user-selected steering mode based on the current operating status of the vehicle, thereby facilitating accurate steering control of the vehicle in the future.

[0183] The foregoing primarily describes the solutions provided by the embodiments of this disclosure from a methodological perspective. To achieve the aforementioned functions, the steering control system includes corresponding hardware structures and / or software modules for executing each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this disclosure can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware 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 disclosure.

[0184] This disclosure embodiment can, according to the above method, exemplarily divide the steering control system into functional modules. For example, the steering control system may include functional modules corresponding to each functional division, or two or more functions may be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this disclosure embodiment is illustrative and only represents one logical functional division; in actual implementation, there may be other division methods.

[0185] As shown in Figure 12, some embodiments of this disclosure provide a vehicle steering control device 1200, which includes a processing component 1201 and an acquisition component 1202; the acquisition component 1202 is configured to acquire a vehicle steering command; the processing component 1201 is configured to, in response to the vehicle steering command, control a first motor corresponding to a first rear wheel of the vehicle to output a first torque and a second motor corresponding to a second rear wheel to output a second torque.

[0186] The first torque has a reverse torque direction, the second torque has a forward torque direction, the first rear wheel is the rear wheel on the steering side of the vehicle, and the second rear wheel is the rear wheel on the non-steering side of the vehicle.

[0187] In one possible implementation, the processing component 1201 is further configured to: in response to a vehicle steering command, control a first motor corresponding to the first rear wheel to output a first torque to achieve rotation of the first rear wheel, and control a second motor corresponding to the second rear wheel to output a second torque to achieve forward rotation of the second rear wheel. The rotation of the first rear wheel includes forward rotation or reverse rotation.

[0188] In one possible implementation, the first torque is determined by: obtaining a first actual slip ratio and a first target slip ratio of the first rear wheel; determining a first slip ratio difference and a first rate of change of the difference based on the first actual slip ratio and the first target slip ratio; the first slip ratio difference is the difference between the first target slip ratio and the first actual slip ratio, and the first rate of change of the difference is the rate of change of the first slip ratio difference per unit time; and determining the first torque based on the first slip ratio difference and the first rate of change of the difference.

[0189] In one possible implementation, the first actual slip ratio is determined by: obtaining the rear axle center point velocity of the vehicle; determining the target wheel speed of the first rear wheel based on the rear axle center point velocity and the vehicle's yaw rate; and determining the actual slip ratio of the first rear wheel based on the target wheel speed and the actual wheel speed of the first rear wheel.

[0190] In one possible implementation, the first target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio map, which indicates the target slip ratio corresponding to each of the vehicle's multiple candidate steering modes, with the steering mode being one of the multiple candidate steering modes.

[0191] In one possible implementation, the processing component 1201 is further configured to: determine a first integral gain coefficient and a first proportional gain coefficient based on a first slip ratio difference and a first rate of change of the difference; and perform a PI operation on the first slip ratio difference based on the first integral gain coefficient and the first proportional gain coefficient to obtain a first torque.

[0192] In one possible implementation, the second torque is determined by: obtaining a second target slip ratio and a second actual slip ratio of the second rear wheel; determining a second slip ratio difference and a second rate of change of the difference based on the second target slip ratio and the second actual slip ratio; the second slip ratio difference is the difference between the second target slip ratio and the second actual slip ratio, and the second rate of change of the difference is the rate of change of the second slip ratio difference per unit time; and determining the second torque based on the second slip ratio difference and the second rate of change of the difference.

[0193] In one possible implementation, the second actual slip ratio is determined by: obtaining the rear axle center point speed of the vehicle; determining the target wheel speed of the second rear wheel based on the rear axle center point speed and the vehicle's yaw rate; and determining the second actual slip ratio based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0194] In one possible implementation, the second target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio map; the slip ratio map indicates the target slip ratio corresponding to each of the vehicle's multiple candidate steering modes, with the steering mode being one of the multiple candidate steering modes.

[0195] In one possible implementation, the processing component 1201 is further configured to: determine a second integral gain coefficient and a second proportional gain coefficient based on the second slip ratio difference and the second difference change rate; and perform a PI operation on the second slip ratio difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain the second torque.

[0196] In one possible implementation, multiple candidate steering modes include a spin turn mode and a non-spin turn mode. The non-spin turn mode includes a normal mode and a track mode. The target slip ratio for the normal mode is less than the target slip ratio for the track mode.

[0197] In one possible implementation, the processing component 1201 is further configured to: when the vehicle is in a turnaround mode, in response to a vehicle steering command, control the braking of the first front wheel and the forward rotation of the second front wheel of the vehicle; the first front wheel is the front wheel on the steering side of the two front wheels of the vehicle, and the second front wheel is the other front wheel of the two front wheels of the vehicle besides the first front wheel.

[0198] In one possible implementation, the processing component 1201 is further configured to: in response to a vehicle steering command, control the braking system of the first front wheel to apply braking force to the first front wheel to achieve braking of the first front wheel, and control the motor of the second front wheel to output a third torque to achieve forward rotation of the second front wheel.

[0199] In one possible implementation, the processing component 1201 is further configured to: when the vehicle is in a non-turnaround mode, in response to a vehicle steering command, control both the first and second front wheels of the vehicle to rotate in the forward direction.

[0200] In one possible implementation, the processing component 1201 is further configured to: in response to a vehicle steering command, control the motors of the first front wheel and the second front wheel to output a third torque so that both the first and second front wheels rotate in the forward direction.

[0201] In one possible implementation, the processing component 1201 is further configured to determine a third torque based on a first mapping relationship between the vehicle's accelerator pedal depth, motor speed, and the vehicle's steering mode. The first mapping relationship is the mapping relationship between the accelerator pedal depth, motor speed, and the third torque; different steering modes correspond to different first mapping relationships.

[0202] In one possible implementation, the processing component 1201 is further configured to: display a steering mode setting interface, which includes multiple candidate steering modes for the vehicle; and determine the vehicle's steering mode from the multiple candidate steering modes in response to a user's setting operation on the steering mode setting interface.

[0203] In one possible implementation, the processing component 1201 is further configured to: in response to the vehicle's operation, exit the vehicle-activated steering mode and adjust the vehicle's current torque at a torque adjustment rate; the torque adjustment rate is determined based on the current torque and the desired torque.

[0204] In one possible implementation, the vehicle operation includes at least one of the following: vehicle speed greater than a preset threshold; brake pedal depth greater than a depth threshold; steering wheel speed greater than a speed threshold; deactivation of steering mode; rear wheel slip rate greater than a slip threshold; rear wheel slip change rate greater than a change threshold; gear shift; and activation of the electronic parking brake.

[0205] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure 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 disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A vehicle steering control method, comprising: In response to a vehicle steering command, the first motor corresponding to the first rear wheel of the vehicle outputs a first torque and the second motor corresponding to the second rear wheel outputs a second torque; wherein the torque direction of the first torque is reversed and the torque direction of the second torque is forward; the first rear wheel is the rear wheel located on the steering side of the vehicle, and the second rear wheel is the rear wheel located on the non-steering side of the vehicle.

2. The method according to claim 1, wherein, The step of responding to a vehicle steering command by controlling the first motor corresponding to the first rear wheel of the vehicle to output a first torque and the second motor corresponding to the second rear wheel to output a second torque includes: In response to the vehicle steering command, the first motor corresponding to the first rear wheel is controlled to output a first torque to achieve rotation of the first rear wheel, and the second motor corresponding to the second rear wheel is controlled to output a second torque to achieve forward rotation of the second rear wheel; The rotation of the first rear wheel can be either forward or reverse.

3. The method according to claim 2, wherein, The first torque is determined in the following way: Obtain the first actual slip ratio and the first target slip ratio of the first rear wheel; Based on the first actual slip ratio and the first target slip ratio, determine the first slip ratio difference and the first rate of change of the first difference; The first slip ratio difference is the difference between the first target slip ratio and the first actual slip ratio, and the rate of change of the first difference is the rate of change of the first slip ratio difference per unit time. The first torque is determined based on the first slip ratio difference and the rate of change of the first difference.

4. The method according to claim 3, wherein, The first actual slip ratio is determined as follows: Obtain the velocity of the rear axle center point of the vehicle; The target wheel speed of the first rear wheel is determined based on the rear axle center point speed and the vehicle yaw rate. The actual slip ratio of the first rear wheel is determined based on the target wheel speed and the actual wheel speed of the first rear wheel.

5. The method according to claim 3 or 4, wherein, The first target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio mapping table, which indicates the target slip ratio corresponding to each of the vehicle's multiple candidate steering modes, wherein the steering mode is one of the multiple candidate steering modes.

6. The method according to any one of claims 3-5, wherein, Determining the first torque based on the first slip ratio difference and the rate of change of the first difference includes: Based on the first slip ratio difference and the rate of change of the first difference, the first integral gain coefficient and the first proportional gain coefficient are determined. Based on the first integral gain coefficient and the first proportional gain coefficient, the first slip ratio difference is subjected to a proportional-integral (PI) operation to obtain the first torque.

7. The method according to any one of claims 2-6, wherein, The second torque is determined in the following way: Obtain the second target slip ratio and the second actual slip ratio of the second rear wheel; Based on the second target slip ratio and the second actual slip ratio, determine the second slip ratio difference and the second rate of change of the difference; The second slip ratio difference is the difference between the second target slip ratio and the second actual slip ratio, and the rate of change of the second difference is the rate of change of the second slip ratio difference per unit time. The second torque is determined based on the second slip ratio difference and the rate of change of the second difference.

8. The method according to claim 7, wherein, The second actual slip ratio is determined in the following way: Obtain the velocity of the rear axle center point of the vehicle; Based on the rear axle center point speed and the vehicle yaw rate, the target wheel speed of the second rear wheel is determined; The second actual slip ratio is determined based on the target wheel speed and the actual wheel speed of the second rear wheel.

9. The method according to claim 7 or 8, wherein, The second target slip ratio is determined based on the vehicle's steering mode and a pre-calibrated slip ratio mapping table; the slip ratio mapping table is used to indicate the target slip ratio corresponding to each of the multiple candidate steering modes of the vehicle, and the steering mode is one of the multiple candidate steering modes.

10. The method according to any one of claims 7-9, wherein, Determining the second torque based on the second slip ratio difference and the rate of change of the second difference includes: Based on the second slip rate difference and the rate of change of the second difference, determine the second integral gain coefficient and the second proportional gain coefficient; Based on the second integral gain coefficient and the second proportional gain coefficient, the second slip ratio difference is subjected to proportional-integral (PI) calculation to obtain the second torque.

11. The method according to claim 5 or 9, wherein, The multiple candidate steering modes include a spin turn mode and a non-spin turn mode. The non-spin turn mode includes a normal mode and a track mode. The target slip ratio corresponding to the normal mode is less than the target slip ratio of the track mode.

12. The method according to any one of claims 1-11, further comprising: When the vehicle is in a turnaround mode, in response to the vehicle steering command, the first front wheel of the vehicle is braked and the second front wheel is rotated in the forward direction; wherein, the first front wheel is the front wheel on the steering side of the two front wheels of the vehicle, and the second front wheel is the other front wheel of the two front wheels of the vehicle besides the first front wheel.

13. The method according to claim 12, wherein, When the vehicle is in a turnaround mode, in response to the vehicle steering command, controlling the braking of the first front wheel and the forward rotation of the second front wheel includes: In response to the vehicle steering command, the braking system of the first front wheel is controlled to apply braking force to the first front wheel to achieve braking of the first front wheel, and the motor of the second front wheel is controlled to output a third torque to achieve forward rotation of the second front wheel.

14. The method of claim 12, further comprising: When the vehicle is in a non-turning mode, in response to the vehicle steering command, the first front wheel and the second front wheel of the vehicle are controlled to rotate in the forward direction.

15. The method according to claim 14, wherein, When the vehicle is in a non-turn-around mode, in response to the vehicle steering command, controlling both the first and second front wheels of the vehicle to rotate in the forward direction includes: In response to the vehicle steering command, the motors of the first front wheel and the second front wheel are controlled to output a third torque so that both the first front wheel and the second front wheel rotate in the forward direction.

16. The method according to claim 13 or 15, further comprising: The third torque is determined based on the first mapping relationship between the accelerator pedal depth, motor speed, and the vehicle's steering mode. The first mapping relationship is the mapping relationship between the accelerator pedal depth, the motor speed, and the third torque; different steering modes correspond to different first mapping relationships.

17. The method according to any one of claims 1-16, further comprising: The steering mode setting interface is displayed, which includes multiple candidate steering modes for the vehicle. In response to a user's setting operation on the steering mode setting interface, the vehicle's steering mode is determined from the plurality of candidate steering modes.

18. The method of claim 17, further comprising: In response to the vehicle's operation, exit the vehicle's active steering mode and adjust the vehicle's current torque at the torque adjustment rate; The torque adjustment rate is determined based on the current torque and the desired torque.

19. The method according to claim 18, wherein, The operation includes at least one of the following: The vehicle speed exceeds a preset threshold; The brake pedal depth is greater than the depth threshold. The steering wheel speed exceeds the speed threshold; Turn off steering mode operation; The rear wheel slip rate is greater than the slip threshold; The rate of change of rear wheel slippage is greater than the change threshold; Gear shift; Electronic parking brake activated.

20. A vehicle steering control device (1200), comprising: The processing component is configured to, in response to a vehicle steering command, control a first motor corresponding to a first rear wheel of the vehicle to output a first torque and a second motor corresponding to a second rear wheel to output a second torque; wherein the torque direction of the first torque is reverse, the torque direction of the second torque is forward, the first rear wheel is the rear wheel on the steering side of the two rear wheels of the vehicle, and the second rear wheel is the other rear wheel of the two rear wheels of the vehicle besides the first rear wheel.

21. A vehicle (100), comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, the processor executing the program to implement the method according to any one of claims 1 to 19.

22. A computer-readable storage medium storing instructions, wherein, When the computer executes the instruction, the computer performs the method according to any one of claims 1 to 19.

23. A computer program product comprising instructions, wherein, when the instructions are executed on a computer, The computer performs the method according to any one of claims 1 to 19.

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