Vehicle steering control method, device and storage medium

Abstract

The present invention discloses a vehicle steering control method, device and storage medium, which relate to the field of vehicle steering technology and can reduce the turning radius of the vehicle. The method comprises: in response to a vehicle steering instruction, 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; wherein the first rear wheel is the rear wheel located on the steering side of the two rear wheels of the vehicle, and the second rear wheel is the rear wheel located on the non-steering side of the vehicle.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle steering, and in particular to a vehicle steering control method, device and storage medium. Background Art

[0002] In the relevant technology, steering performance is one of the basic characteristics of a vehicle, and the key indicator for evaluating steering performance is the turning radius of the vehicle. At present, when a vehicle is turning, both the front wheels and the rear wheels of the vehicle turn in the turning direction, which easily leads to the problem of the vehicle turning radius being too large. Summary of the invention

[0003] The embodiments of the present application provide a vehicle steering control method, device and storage medium, which can reduce the turning radius of the vehicle. It should be understood that the vehicle steering control method provided in the embodiments of the present application can be applied to vehicles with distributed three motors, and can also be applied to vehicles with four-wheel independent drive or rear-wheel independent drive to achieve the function of turning in place.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] In a first aspect, the present invention provides a vehicle steering control method, the method comprising: 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.

[0006] 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 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.

[0007] 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 of the vehicle to output a second torque includes: in response to the 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 positive rotation of the second rear wheel;

[0008] The rotation of the first rear wheel includes forward rotation or reverse rotation.

[0009] In some embodiments, the first torque is determined by: obtaining a first actual slip rate and a first target slip rate of the first rear wheel; determining a first slip rate difference and a first difference change rate based on the first actual slip rate and the first target slip rate; the first slip rate difference is the difference between the first target slip rate and the first actual slip rate, and the first difference change rate is the change rate of the first slip rate difference in unit time; and determining the first torque based on the first slip rate difference and the first difference change rate.

[0010] In some embodiments, the first actual slip rate is determined according to the following method: obtaining the rear axle center point speed of the vehicle; determining the target wheel speed of the first rear wheel based on the rear axle center point speed and the yaw angular velocity of the vehicle; determining the actual slip rate of the first rear wheel based on the target wheel speed of the first rear wheel and the actual wheel speed of the first rear wheel.

[0011] In some embodiments, the first target slip ratio is determined based on a steering mode of the vehicle and a pre-calibrated slip ratio mapping table, where the slip ratio mapping table is used to indicate target slip ratios corresponding to each of a plurality of candidate steering modes of the vehicle, and the steering mode is one of the plurality of candidate steering modes.

[0012] In some embodiments, determining a first torque based on a first slip ratio difference and a first difference change rate includes: determining a first integral gain coefficient and a first proportional gain coefficient based on the first slip ratio difference and the first difference change rate; and performing a 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.

[0013] In some embodiments, the second torque is determined by: obtaining a second target slip rate and a second actual slip rate of the second rear wheel; determining a second slip rate difference and a second difference change rate based on the second target slip rate and the second actual slip rate; the second slip rate difference is the difference between the second target slip rate and the second actual slip rate, and the second difference change rate is the change rate of the second slip rate difference in unit time; and determining the second torque based on the second slip rate difference and the second difference change rate.

[0014] In some embodiments, the second actual slip rate 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 angular velocity of the vehicle; and determining the second actual slip rate based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0015] In some embodiments, the second target slip ratio is determined based on a steering mode of the vehicle and a pre-calibrated slip ratio mapping table; the slip ratio mapping table is used to indicate target slip ratios corresponding to each of a plurality of candidate steering modes of the vehicle, and the steering mode is one of the plurality of candidate steering modes.

[0016] In some embodiments, the second torque is determined based on the second slip rate difference and the second difference change rate, including: determining the second integral gain coefficient and the second proportional gain coefficient based on the second slip rate difference and the second difference change rate; performing a PI operation on the second slip rate difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain the second torque.

[0017] In some embodiments, the plurality of candidate steering modes include a rotational U-turn mode and a non-rotational U-turn mode, the non-rotational U-turn mode includes a normal mode and a track mode, and a target slip ratio corresponding to the normal mode is smaller than a target slip ratio of the track mode.

[0018] In some embodiments, the method also includes: when the vehicle is in a rotation turn mode, in response to a vehicle steering command, controlling the braking of the first front wheel of the vehicle and the forward rotation of the second front wheel; 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 except the first front wheel.

[0019] In some embodiments, when the vehicle is in a turn mode, in response to a vehicle steering command, the first front wheel of the vehicle is braked and the second front wheel is rotated forward, including: in response to the vehicle steering command, controlling the braking system of the first front wheel to apply a 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.

[0020] In view of this, in the rotational U-turn 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, so that the vehicle can turn on the spot with an extremely small turning radius, and the vehicle can generate a yaw torque while allowing the user to experience a "tail drift" effect.

[0021] In some embodiments, the method further comprises: when the vehicle is in a non-rotational U-turn mode, in response to a vehicle steering command, controlling both the first front wheel and the second front wheel of the vehicle to rotate forward.

[0022] In some embodiments, when the vehicle is in a non-rotating U-turn mode, in response to a vehicle steering command, the first front wheel and the second front wheel of the vehicle are controlled to rotate forward, including: in response to the vehicle steering command, controlling the motor of the first front wheel and the motor of the second front wheel to output a third torque to achieve forward rotation of the first front wheel and the second front wheel.

[0023] In some embodiments, the method further includes: determining the third torque based on a first mapping relationship corresponding to an accelerator pedal depth, a motor speed, and a steering mode of the vehicle. The first mapping relationship is a mapping relationship between the accelerator pedal depth, the motor speed, and the third torque; different steering modes correspond to different first mapping relationships.

[0024] In some embodiments, the method also includes: displaying a steering mode setting interface, the steering mode setting interface including multiple candidate steering modes for the vehicle; and determining the steering mode of the vehicle from the multiple candidate steering modes in response to a user's setting operation on the steering mode setting interface.

[0025] In some embodiments, the method further includes: in response to an operating operation of the vehicle, exiting a steering mode activated by the vehicle and adjusting a current torque of the vehicle at a torque adjustment rate; the torque adjustment rate is determined based on the current torque and the desired torque.

[0026] In some embodiments, the operating operation includes at least one of the following: vehicle speed is greater than a preset threshold; brake pedal depth is greater than a depth threshold; steering wheel speed is greater than a speed threshold; steering mode operation is turned off; rear wheel slip rate is greater than a slip threshold; rear wheel slip change rate is greater than a change threshold; gear change; electronic parking brake activation.

[0027] In a second aspect, an embodiment of the present application provides a vehicle steering control device, which includes: a processing unit; a processing unit, for 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 in response to a vehicle steering command.

[0028] 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 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.

[0029] In a third aspect, the present application provides a vehicle, 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.

[0030] In a fourth aspect, the present application provides a computer-readable storage medium, in which instructions are stored. When the instructions are executed on a terminal, the terminal executes the vehicle steering control method described above.

[0031] In a fifth aspect, the present application provides a computer program product comprising instructions, and when a computer executes the above instructions, the computer executes the vehicle steering control method described above.

[0032] In a sixth aspect, the present application provides a chip, the chip including a processor and a communication interface, the communication interface and the processor are coupled, and the processor is used to run a computer program or instructions to implement the vehicle steering control method described above.

[0033] Specifically, the chip provided in the embodiment of the present application also includes a memory for storing computer programs or instructions.

[0034] Based on the above technical solution, the vehicle steering control method provided in the embodiment of the present application, the steering control system controls the first motor corresponding to the first rear wheel of the vehicle to output a first torque with a reverse direction and the second motor corresponding to the second rear wheel to output a second torque with a positive direction in response to the vehicle steering command, so that when the vehicle turns, the rotation speed of the second rear wheel is higher than the rotation speed of the first rear wheel, thereby generating a wheel speed difference between the two rear wheels, and the wheel speed difference can enable the vehicle to turn more flexibly, thereby reducing the turning radius. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 A schematic diagram of an Ackerman turning angle of a vehicle provided in an embodiment of the present application;

[0037] Figure 2 A vehicle architecture diagram provided in an embodiment of the present application;

[0038] Figure 3 An architectural diagram of a steering control system provided in an embodiment of the present application;

[0039] Figure 4 A flow chart of a vehicle steering control method provided in an embodiment of the present application;

[0040] Figure 5 A scene diagram of a non-rotational U-turn mode provided in an embodiment of the present application;

[0041] Figure 6 A scene diagram of a rotation turning mode provided in an embodiment of the present application;

[0042] Figure 7 A schematic diagram of longitudinal force and lateral force coefficients under different slip rates provided in an embodiment of the present application;

[0043] Figure 8 A schematic diagram of a fuzzy PI control algorithm provided in an embodiment of the present application;

[0044] Fig. 9 A flowchart of another vehicle steering control method provided in an embodiment of the present application;

[0045] Fig.10 A schematic diagram of activating a steering mode provided in an embodiment of the present application;

[0046] Fig.11 A schematic diagram of a steering mode exit provided in an embodiment of the present application;

[0047] Fig.12 A schematic diagram of a vehicle steering control device is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "back", "inside", "outside" and the like indicate directions or positional relationships based on the directions or relative positional relationships shown in the accompanying 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention. Unless otherwise specified, the above-mentioned directional description can be flexibly set in the process of actual application under the condition that the relative positional relationship shown in the accompanying drawings is satisfied.

[0050] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0051] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. It can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the embodiments of the present invention, the terms "comprises", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, article or device including the element.

[0053] In the embodiments of the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0054] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0055] In the relevant technology, the steering performance of a vehicle is one of its basic characteristics, and the key indicator for evaluating the steering performance is the turning radius of the vehicle. The minimum turning radius refers to the radius of the trajectory circle drawn by the center of the outer steering wheel on the support surface when the steering wheel is turned to the extreme position and the vehicle is turning at the lowest stable speed.

[0056] For traditional vehicles, the minimum turning radius is mainly determined by the wheelbase and the maximum front wheel turning angle. Generally, once the vehicle is designed and finalized, its minimum turning radius is also determined. The minimum turning radius also largely reflects the vehicle's ability to pass through narrow curved areas or bypass obstacles that cannot be passed directly.

[0057] like Figure 1 As shown, during the current turning process of the vehicle, both the front wheels and the rear wheels of the vehicle rotate in the turning direction, which may easily affect the minimum turning radius of the vehicle and cause the turning radius R to be too large.

[0058] Among them, V L1 is the speed of the front wheel on the turning side, V R1 is the speed of the front wheel on the non-turning side, V L2 is the speed of the rear wheel on the turning side, V R2 is the speed of the rear wheel on the non-turning side.

[0059] The implementation of the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

[0060] like Figure 2, which is a structural diagram of a vehicle provided in an embodiment of the present application, the vehicle 100 may include a chassis 110, a body 120, and wheels 130. It is understandable that the vehicle 100 may be a fuel vehicle, an electric vehicle, a hybrid vehicle, a gas vehicle, a methanol vehicle, a solar vehicle, etc.

[0061] For example, the vehicle 100 may be a passenger vehicle such as a sedan, a sport utility vehicle (SUV), a multi-purpose vehicle (MPV), or a bus, a truck, a semi-trailer, etc. This application does not impose any specific restrictions on this.

[0062] It is understandable that the above components are merely examples of some components of the vehicle 100 and are not limitations on the specific structure of the vehicle 100 .

[0063] Optionally, in order to control the vehicle, the vehicle 100 may further include a steering control system 140 . The steering control system 140 may implement steering control of the vehicle 100 .

[0064] like Figure 3 , which is an architecture diagram of a steering control system provided in an embodiment of the present application. The steering control system 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).

[0065] In some embodiments, the vehicle controller 230 sends a vehicle steering instruction to the steering system 210, and the steering system 210 controls the first motor corresponding to the vehicle to output a first torque and the second motor corresponding to the second rear wheel to output a second torque.

[0066] 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 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.

[0067] Exemplarily, the vehicle controller 230 can receive the driver's steering intention signal and send a vehicle steering instruction to the steering system 210, thereby controlling the rear wheel motor to output a first torque to achieve rotation of the first rear wheel, and controlling the rear wheel motor to output a second torque to achieve reverse rotation of the second rear wheel.

[0068] The rotation of the first rear wheel includes forward rotation or reverse rotation.

[0069] Optionally, the rear wheel motor includes a first motor 250 corresponding to the first rear wheel and a second motor 260 corresponding to the second rear wheel.

[0070] In another example, the vehicle controller 230 can receive a steering intention signal from the driver, and when the entry conditions of 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 achieve 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 achieve the forward rotation of the second rear wheel.

[0071] Similarly, the front wheel motor 240 can output torque to achieve front wheel rotation.

[0072] In some embodiments, the vehicle controller 230 may control the brake control system 220 to apply braking force to any one or more wheels of the vehicle in response to a vehicle steering command.

[0073] Optionally, the steering control system 140 further includes: a front axle differential 270 , which is disposed on the front axle of the vehicle and is mechanically connected to the front wheel motor 240 .

[0074] The front axle differential 270 is used to adjust the speed difference between the inner and outer drive wheels when the vehicle turns, ensuring that the speed of the outer wheels is higher than that of the inner wheels, thereby improving the turning performance of the vehicle.

[0075] Optionally, 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 used to measure the rotation speed of the wheels of the vehicle during driving, that is, the wheel speed information, and send the wheel speed information of the four wheels of the vehicle to the vehicle controller 230.

[0076] The wheels of the vehicle correspond to the wheel speed sensors 280 one by one.

[0077] Optionally, 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 used to monitor the motion trajectory of the vehicle around its vertical axis (i.e., longitudinal axis) to determine whether the vehicle is sliding or out of control, and send the vehicle's yaw information to the vehicle controller 230.

[0078] It should be noted that the control system described in the embodiment of the present application is to more clearly illustrate the technical solution of the embodiment of the present application, and does not constitute a limitation on the technical solution provided in the embodiment of the present application. It is known to those skilled in the art that with the evolution of electronic devices and the emergence of other electronic devices, the technical solution provided in the embodiment of the present application is also applicable to similar technical problems. The methods in the following embodiments can all be implemented in a control system having the above hardware structure.

[0079] The methods in the following embodiments can all be implemented in a control system having the above hardware structure.

[0080] The vehicle steering control method provided by the embodiment of the present application is described in detail below in conjunction with the accompanying drawings.

[0081] The vehicle steering control method of the embodiment of the present application can be applied to the steering control of a vehicle. Figure 4 As shown, the vehicle steering control method may include steps 301 and 302. Step 301 may also be referred to as a process of "obtaining a vehicle steering instruction", and step 302 may be referred to as a process of "steering control of a vehicle". Steps 301 and 302 are described in detail below.

[0082] Step 301: Obtain vehicle steering instructions.

[0083] 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 a rear wheel on the steering side of the vehicle, and the second rear wheel is a rear wheel on the non-steering side of the vehicle. The first rear wheel can be called an inner rear wheel, and the second rear wheel can be called an outer rear wheel, without limitation.

[0084] 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, wherein the first front wheel is a front wheel located on the steering side of the two front wheels of the vehicle, and the second front wheel is another front wheel of the two front wheels of the vehicle except the first front wheel.

[0085] Step 302 , 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 of the vehicle to output a second torque.

[0086] The torque direction of the first torque is reverse, and the torque direction of the second torque is forward.

[0087] As a possible implementation, in response to a vehicle steering command, a first motor corresponding to a first rear wheel is controlled to output a first torque to achieve rotation of the first rear wheel, and a second motor corresponding to a second rear wheel is controlled to output a second torque to achieve positive rotation of the second rear wheel. The rotation of the first rear wheel includes positive rotation or reverse rotation.

[0088] It should be understood that when the vehicle turns, in addition to the steering force and steering direction of the front wheels, the rear-wheel steering system can cause the rear wheels to also generate a steering angle. By controlling the motor output torque of the inner rear wheel to be a first torque in the reverse direction, it helps to reduce the rotation speed of the inner rear wheel; and controlling the motor output torque of the outer rear wheel to be a second torque in the forward direction helps to increase the rotation speed of the outer wheel, applying a yaw moment in the same direction as the steering direction to the vehicle, allowing the wheel to turn with a smaller turning radius.

[0089] Furthermore, because the reverse rotation of the inner rear wheel reduces the speed of the inner wheel, making it easier for the vehicle to tilt inward, the positive rotation of the outer rear wheel increases the speed and friction of the outer wheel, exerting a yaw moment in the same direction as the steering direction on the vehicle. Combining the two, the vehicle can travel more compactly around the center point when turning, thereby reducing the turning radius of the vehicle.

[0090] The vehicle provided in the embodiment of the present application has a plurality of different candidate steering modes, such as a rotational U-turn mode and a non-rotational U-turn mode. Among them, the rotational U-turn mode is used for rapid U-turns of the vehicle on narrow roads; the non-rotational U-turn mode includes at least one of the following: normal mode and track mode. The normal mode can be used as a normalized start-up mode of the vehicle, which can reduce tire wear and increase the smoothness of the vehicle's driving. The track mode allows the vehicle to quickly pass through a U-turn, and reduces the vehicle's cornering time by adjusting the torque output of the motor.

[0091] In some embodiments, when in the non-rotational U-turn mode, in response to a vehicle steering command, both the first front wheel and the second front wheel of the vehicle are controlled to rotate forward.

[0092] For example, in combination Figure 5 As shown, when the vehicle is in normal mode or track mode, the steering control system responds to the first front wheel and the second front wheel forward rotation command, controls the motor of the first front wheel and the motor of the second front wheel to output the third torque to realize the first front wheel and the second front wheel to rotate forward, and responds to the first rear wheel rotation command and the second rear wheel forward rotation command, controls the first motor corresponding to the first rear wheel to output the first torque to realize the rotation of the first rear wheel, and controls the second motor corresponding to the second rear wheel to output the second torque to realize the forward rotation of the second rear wheel. The rotation of the first rear wheel can be forward rotation or reverse rotation, which is not limited in the embodiment of the present application.

[0093] It can be understood that the steering control system controls the first motor of the first rear wheel of the vehicle to output torque in the reverse direction to achieve rotation of the first rear wheel and controls the second motor of the second rear wheel to output torque in the forward direction to achieve positive rotation of the second rear wheel in response to the vehicle steering command. When the vehicle turns, the rotation speed of the second rear wheel is higher than the rotation speed of the first rear wheel, thereby generating a wheel speed difference between the two rear wheels. The wheel speed difference can enable the vehicle to turn more flexibly, thereby reducing the turning radius.

[0094] It should be understood that the torque output by the motor in the normal mode and the track mode is different, so different purposes can be achieved. In addition, the target slip ratio corresponding to the normal mode is smaller than the target slip ratio of the track mode.

[0095] In some embodiments, when the vehicle is in a rotation turn mode, in response to a vehicle steering command, a first front wheel of the vehicle is controlled to be braked and a second front wheel is controlled to be turned forward.

[0096] For example, Figure 6 As shown, in response to a first front wheel braking command, the braking system of the first front wheel is controlled to apply a braking force to the first front wheel so as to brake the first front wheel, and in response to a second front wheel forward rotation command, the motor of the second front wheel is controlled to output a third torque so as to enable the second front wheel to rotate forward, and in response to a first rear wheel rotation command and a second rear wheel forward rotation 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.

[0097] It should be noted that, in the rotation turn mode, if the rotation of the first rear wheel is in the reverse direction, the turning radius of the vehicle can be further reduced.

[0098] The braking force applied to the first front wheel is proportional to the accelerator pedal depth of the vehicle. 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 of the vehicle when 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 at a certain slip rate to avoid wheel wear.

[0099] It should be understood that applying braking force to the front wheel on the steering side can generate a deceleration when the vehicle turns, which can form a force toward the inside of the curve. This inner force can help the vehicle to run more closely along the U-turn curve. In other words, when applying braking force to the front wheel on the steering side, due to the larger steering angle and lower speed of the front wheel, the vehicle will be more inclined to turn around the front wheel (static steering center point), thereby reducing the turning radius. In conjunction with the reverse rotation of the first rear wheel and the forward rotation of the second rear wheel, the turning radius of the vehicle can be further reduced.

[0100] The above is a detailed overview of how to perform vehicle steering control. The following is a detailed introduction on 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.

[0101] In one possible implementation, the first torque of the first rear wheel may be determined in the following manner: obtaining a first actual slip rate and a first target slip rate of the first rear wheel, and determining a first slip rate difference and a first difference change rate based on the first actual slip rate and the first target slip rate, and then determining the first torque based on the first slip rate difference and the first difference change rate.

[0102] 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 change rate of the first slip ratio difference in unit time. The slip ratio refers to the proportion of the slip component of the wheel in the longitudinal motion of the wheel.

[0103] It should be noted that the first target slip ratio can be determined based on the steering mode of the vehicle and a pre-calibrated slip ratio mapping table, and the slip ratio mapping table is used to indicate the target slip ratios corresponding to each of the multiple candidate steering modes of the vehicle. In other words, the first target slip ratio of the corresponding first rear wheel can be obtained according to the steering mode of the vehicle. For example, when the vehicle is in normal mode, the first target slip ratio of the first rear wheel can be obtained according to the slip ratio mapping table corresponding to the normal mode. Similarly, when the vehicle is in track mode or rotation mode, the slip ratio mapping table of the corresponding mode can be obtained accordingly to obtain the target slip ratio.

[0104] It should be understood that the user can select a steering mode that meets the driving habits according to the needs, and then the steering control system can obtain the corresponding slip ratio mapping table according to the steering mode selected by the user, so as to obtain the first target slip ratio of the first rear wheel. The degree of reduction of the turning radius of the vehicle by different steering modes can be: normal mode < track mode < rotation mode, that is, the rotation mode has the greatest degree of reduction in the turning radius, followed by the track mode, and finally the normal mode.

[0105] In some embodiments, Figure 7As shown in the figure, in order to effectively reduce the turning radius of the vehicle, the rear wheels of the vehicle will indeed have a certain degree of slip or sliding when turning. However, when the driving force of the tire reaches its limit, the longitudinal adhesion of the tire will drop significantly, which will lead to a decrease in vehicle stability. Therefore, during the control process, the output torque of the rear wheels must be accurately controlled to prevent the rear wheels from over-rotating (i.e., spinning).

[0106] It should be understood that when the vehicle is in a straight-line driving state or is turning at a small steering angle, the wheel slip rate S and the slip rate S t The calculation formulas for may be the following formulas 1 and 2.

[0107] Formula 1;

[0108] Formula 2;

[0109] Where, v is the vehicle speed, w is r is the angular velocity of the wheel, and r is the rolling radius of the wheel.

[0110] In conventional vehicle speed estimation, the average of the wheel speeds of the two non-driven front wheels or two rear wheels is usually used to approximate the vehicle speed. However, when the vehicle turns at a large steering angle, this method will produce deviations. This is because the wheel speed of the inner wheel will be lower than that of the outer wheel, and the wheel speed of the front wheel is generally higher than that of the rear wheel. If the slip rate S and slip rate are still calculated using the above formulas 1 and 2 , will lead to inaccurate results, thereby weakening the performance of the steering control system. Therefore, the embodiment of the present application provides a first actual slip rate, as shown below.

[0111] In some embodiments, the first actual slip ratio may 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 angular velocity 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.

[0112] It should be noted that when both front wheels are rotating forward, the rear axle center speed is determined based on the front axle center speed. When the first front wheel is braked and the second front wheel is rotating forward, the rear axle center speed is determined based on the actual wheel speed of the second front wheel.

[0113] An example, combined with Figure 1 As shown, when the vehicle turns, the single-track bicycle model can be used to obtain , by simplifying this formula, we can get the formula 3 for the turning radius R of the vehicle.

[0114] Formula 3;

[0115] in, , δ1 is the left front wheel turning angle, δ2 is the left and right front wheel turning angles, L is the vehicle wheelbase, b is the distance from the center of mass to the rear axle, and B is the vehicle's wheelbase.

[0116] According to the vehicle dynamics characteristics, the yaw angular velocity of each point on the vehicle is equal, and the following formula 4 can be obtained.

[0117] Formula 4;

[0118] Among them, V 1 is the front axle center speed, V 2 is the rear axle center speed, V R1 is the theoretical wheel speed of the right front wheel.

[0119] The rear axle center speed V can be obtained by the above formula 4 2 , and then the theoretical wheel speed of the left rear wheel and the theoretical wheel speed of the right rear wheel can be calculated according to the following formula 5 and formula 6.

[0120] Formula 5;

[0121] Formula 6;

[0122] Among them, V L2 is the theoretical wheel speed of the left rear wheel, V R2 is the theoretical wheel speed of the right rear wheel, and w is the yaw angular velocity of the vehicle.

[0123] After calculating and determining the theoretical wheel speed of the rear wheel, the slip rate or slip ratio of the rear wheel can be determined according to the theoretical wheel speed and the actual wheel speed of the rear wheel, as shown in the following formula 7 and formula 8.

[0124] Formula 7;

[0125] Formula 8;

[0126] in, is the slip rate, is the slip rate, V v is the theoretical wheel speed, V w is the actual wheel speed.

[0127] Another example, combined with Figure 5As shown, the vehicle is in a non-rotating U-turn mode. At this time, the motor output torque of the first rear wheel is the first torque in the reverse direction, which makes the first rear wheel rotate, and the motor output torque of the second rear wheel is the second torque in the positive direction, which makes the second rear wheel rotate positively and makes the two front wheels rotate positively to the steering side. Since the two front wheels have no slip rate, the wheel speed of the two front wheels can be approximately expressed as the front axle center point speed V 1 , the front axle center speed V is obtained by the following formula 9 1 .

[0128] Formula 9;

[0129] in, is the actual wheel speed of the first front wheel, is the actual wheel speed of the second front wheel, is the turning angle of the outer front wheel.

[0130] Then, substitute the above formula 9 into the following formula 10 to obtain the rear axle center speed: , that is, according to the front axle center speed V 1 Calculate the rear axle center speed :

[0131] Formula 10;

[0132] The rear axle center speed Substituting the yaw rate w of the vehicle into the following formula 11 and formula 12, the slip rate S of the first rear wheel is obtained respectively. L2 and the slip rate T of the second rear wheel R2 .

[0133] Formula 11;

[0134] Formula 12;

[0135] in, is the target wheel speed (theoretical wheel speed) of the first rear wheel, which can be understood as ; is the actual wheel speed of the first rear wheel, which can be understood as .

[0136] In some embodiments, the steering control system may determine a first integral gain coefficient and a first proportional gain coefficient based on the first slip ratio difference and the first difference change rate, 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.

[0137] For example, Figure 8 As shown, according to the first target slip ratio and the first actual slip ratio, the first slip ratio difference and the first difference change rate are determined, and the first slip ratio difference and the first difference change rate are input into the PI fuzzy rule table to obtain the adaptive proportional gain coefficient K. p and integral gain coefficient K i , and then the proportional gain coefficient K p and integral gain coefficient K i Enter the proportional-integral ( , PI) control system, determines a first torque of the first rear wheel.

[0138] Among them, the PI fuzzy rule table includes K p Fuzzy rule table and K i Fuzzy rule table. The details are shown in Table 1 and Table 2 below.

[0139] Table 1 K p Fuzzy rule table

[0140]

[0141] Table 2 K i Fuzzy rule table

[0142]

[0143] In the above Tables 1 and 2, NL is negative and large, NM is negative and medium, NS is negative and small, ZE is zero, PS is positive and small, PM is positive and medium, and PL is positive and large.

[0144] For example, a two-dimensional table lookup can be performed based on the first difference change rate EC and the first slip ratio difference E to determine the proportional gain coefficient K of the first rear wheel. p and integral gain coefficient K i .

[0145] Take the first difference change rate EC as 0% and the first slip rate difference E as 0.2 as an example. First check K p Fuzzy rule table, since the first difference change rate EC is 0%, the fuzzy value of the first difference change rate EC can be determined to be ZE, and the first slip rate difference E is 0.2, the fuzzy value of the first slip rate difference E can be determined to be PS. Combining ZE with PS, the proportional gain coefficient K can be obtained. p is NS, integral gain coefficient K i is ZE, and then the proportional gain coefficient K p (NS), integral gain coefficient K i (ZE) is input into the PI control system to obtain a first torque of the first rear wheel.

[0146] Optionally, when the steering control system is in the initial stage, the first slip ratio difference E is relatively large, and a relatively large proportional gain coefficient K can be obtained by the above two-dimensional table lookup method. p And a smaller integral gain coefficient K i , to improve the system's response speed.

[0147] When the steering control system is in the pre-stabilization stage, the first slip ratio difference E is within a certain range, and the slip ratio of the steering control is near the target value. At this time, the proportional gain coefficient K p and integral gain coefficient K i Just keep it at the right size.

[0148] When the steering control system is in a stable stage, the first slip ratio difference E is very small. In order to improve the system robustness and response speed, the proportional gain coefficient K can be appropriately increased. p and integral gain coefficient K i .

[0149] In one possible implementation, the second torque of the second rear wheel can be determined in the following manner: obtain the second target slip rate and the second actual slip rate corresponding to the second rear wheel, and determine the second slip rate difference and the second difference change rate based on the second target slip rate and the second actual slip rate, and then determine the second torque based on the second slip rate difference and the second difference change rate.

[0150] The second slip rate difference is the difference between the second target slip rate and the second actual slip rate, and the second difference change rate is the change rate of the second slip rate difference in unit time. The slip rate refers to the degree of wheel slippage during driving.

[0151] It should be noted that the second target slip rate is determined based on the vehicle's steering mode and a pre-calibrated slip rate mapping table; the slip rate mapping table is used to indicate the target slip rates corresponding to each of the multiple candidate steering modes of the vehicle. In other words, the second target slip rate of the corresponding second rear wheel can be obtained according to the vehicle's steering mode. For example, when the vehicle is in normal mode, the second target slip rate of the second rear wheel can be obtained according to the slip rate mapping table corresponding to the normal mode. Similarly, when the vehicle is in track mode or turn mode, the slip rate mapping table of the corresponding mode can be obtained accordingly to obtain the target slip rate.

[0152] In some embodiments, the second actual slip rate 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 angular velocity of the vehicle, and then determining the second actual slip rate based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0153] For example, in combination Figure 6 As shown, the vehicle is in the U-turn mode. At this time, the motor output torque direction of the first rear wheel is the first torque in the reverse direction, which makes the first rear wheel rotate, and the motor output torque direction of the second rear wheel is the second torque in the positive direction, which makes the second rear wheel rotate positively, and applies braking force to the first front wheel and third torque to the second front wheel. Since the first front wheel (the front wheel on the steering side) is in the braking state, the rear axle center point speed V can be calculated based on the actual wheel speed of the second front wheel. 2 , as shown in the following formula 13.

[0154] Formula 13;

[0155] Then, the rear axle center speed V obtained above can be 2 Substituting into the above formula 11 and formula 12, the slip rate S of the first rear wheel is obtained. L2 and the slip rate T of the second rear wheel R2 .

[0156] Optionally, the actual wheel speeds of the above wheels are obtained through wheel speed sensors installed on the wheels. However, when the vehicle is in non-turn mode or turn mode, the wheel speeds may be low. At this time, the wheel speeds collected by the wheel speed sensors have problems such as low accuracy and slow update speed. Therefore, the wheel speeds obtained by the motor speed and the wheel speeds collected by the wheel speed sensors can be weighted before calculating the wheel slip rate or slip rate. Calculated wheel speed The method is shown in the following formula 14.

[0157] Formula 14;

[0158] Among them, r is the rolling radius of the wheel, and rat is the transmission ratio of the motor.

[0159] In some embodiments, the steering control system determines a second integral gain coefficient and a second proportional gain coefficient based on the second slip difference and the second difference change rate, and performs a PI operation on the second slip difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain a second torque.

[0160] Exemplarily, according to the second target slip rate and the second actual slip rate, the second slip rate difference and the second difference change rate are determined, and the second slip rate difference and the second difference change rate are input into the PI fuzzy rule table, so as to obtain the adaptive proportional gain coefficient K p and integral gain coefficient K i , and then the proportional gain coefficient K p And the integral gain coefficient Ki is input into the PI control system to determine the second torque of the second rear wheel.

[0161] For example, the steering control system can perform a two-dimensional table lookup based on the second difference change rate EC and the second slip rate difference E to determine the proportional gain coefficient K of the second rear wheel. p and integral gain coefficient K i It can be understood that the proportional gain coefficient K of the second rear wheel p and integral gain coefficient K i The proportional gain coefficient K of the first rear wheel p and integral gain coefficient K i The determination method is the same and will not be repeated here.

[0162] Preferably, an adaptive fuzzy PI control algorithm is used in the embodiment of the present application to control the slip rate (or slip ratio) of the wheel near the desired slip rate. The present application does not limit the PI control algorithm, and other control algorithms may also be used.

[0163] It should be noted that the slip rate or slip ratio mentioned in the embodiments of the present application may also be replaced by wheel speed, and the present application does not limit this.

[0164] In one possible implementation, the third torque of the second front wheel may be determined based on an accelerator pedal depth, a motor speed, and a steering mode of the vehicle.

[0165] In some embodiments, the steering control system may determine the third torque based on a first mapping relationship corresponding to an accelerator pedal depth, a motor speed, and a steering mode of the vehicle.

[0166] The first mapping relationship is a mapping relationship among the accelerator pedal depth, the motor speed and the third torque; different steering modes correspond to different first mapping relationships.

[0167] Exemplarily, according to the current steering mode of the vehicle, a corresponding weighted acceleration curve diagram (first mapping relationship) is determined, and then the corresponding third torque is obtained in the weighted acceleration curve diagram according to the accelerator pedal depth and the motor speed.

[0168] Optionally, the driver can control the torque output of the motor and thus the speed of the vehicle by adjusting the depth of the accelerator pedal.

[0169] In the above, 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 is introduced in detail.

[0170] It should be understood that the vehicle steering control method provided in the embodiment of the present application can be applied to vehicles with distributed three motors, and can also be applied to vehicles with four-wheel independent drive or rear-wheel independent drive to achieve the on-the-spot steering function.

[0171] Based on the above technical solution, the steering control system controls the motor output torque direction of the first rear wheel of the vehicle to be a reverse first torque, and the motor output torque direction of the second rear wheel to be a forward second torque in response to the vehicle steering command, so that when the vehicle turns, the rotation speed of the second rear wheel is higher than the rotation speed of the first rear wheel, thereby generating a wheel speed difference between the two rear wheels. The wheel speed difference can enable the vehicle to turn more flexibly, thereby reducing the turning radius.

[0172] like Fig. 9 As shown, the overall process of the vehicle steering control method provided in the embodiment of the present application is summarized, which specifically includes the following steps 901-905.

[0173] Step 901: Display the steering mode setting interface.

[0174] Among them, the steering mode setting interface includes multiple candidate steering modes of the vehicle, and the multiple candidate steering modes include normal mode, track mode and rotation turn mode.

[0175] The normal mode can be used as a normalized function. This mode can reduce tire wear and increase the smoothness of vehicle driving. In this mode, the slip rate of the first rear wheel and the slip rate 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%.

[0176] Track mode can be used for the vehicle to quickly pass through a U-shaped sharp turn, thereby reducing the vehicle's cornering time. It should be understood that when the conditions for entering the track racing mode are met, the vehicle's state at this time can be judged based on signals such as the current vehicle speed, steering wheel angle, yaw rate, etc., to adjust the torque output of the front and rear motors in real time to reduce the vehicle's cornering time.

[0177] The rotational U-turn mode can be used for vehicle U-turns on narrow roads. When the conditions for entering the rotational U-turn mode are met, turn the steering wheel fully clockwise (or counterclockwise) and the accelerator 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 a first torque in the reverse direction and the motor output torque of the second rear wheel to be a second torque in the forward direction. The vehicle generates a transverse torque along the steering direction to achieve a quick U-turn.

[0178] For example, the vehicle's central control display screen can display multiple candidate steering modes of the vehicle for the user to select. The driver can touch a physical button or a virtual button to select different candidate steering modes.

[0179] Step 902: In response to a setting operation of a user on a steering mode setting interface, a steering mode of the vehicle is determined from a plurality of candidate steering modes.

[0180] For example, the user can view multiple candidate steering modes displayed on the central control screen and select the desired steering mode according to his or her own needs. The vehicle can determine the steering mode of the vehicle in response to the user's setting operation.

[0181] Step 903: Based on the running state of the vehicle, determine whether to activate the steering mode of the vehicle.

[0182] The running state of the vehicle includes at least one of the following: driving state, curve state, and curve exit state.

[0183] The operating state of the vehicle 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, center of mass sideslip angle, center of mass sideslip angle acceleration, lateral acceleration, and longitudinal acceleration.

[0184] In some embodiments, Fig.10 As shown, the steering control system can input the accelerator pedal depth, brake pedal depth, steering wheel angle, yaw rate, center of mass sideslip angle, center of mass sideslip angle acceleration, lateral acceleration, and longitudinal acceleration into a state recognition unit to determine the current operating state of the vehicle.

[0185] Furthermore, when the running state of the vehicle changes from the driving state to the turning state in the curve state, the steering mode of the vehicle is activated.

[0186] Exemplarily, when the user selects the normal mode for the vehicle steering mode and the vehicle is idling, it is determined whether the steering wheel angle is greater than a first angle threshold. If so, it is determined that the vehicle's operating state has changed from a driving state to a turning state, thereby activating the normal mode.

[0187] In another example, when the user selects the track mode for 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 an angle threshold. If both are greater, it is determined that the vehicle's operating state has changed from a driving state to a cornering state, thereby activating the track mode.

[0188] Optionally, to determine whether to activate the track mode, it is also possible to further determine whether the accelerator pedal depth is greater than a threshold value, and whether the self-propelled slip angle is greater than an angle threshold (the angle between the vehicle's moving direction and the steering wheel). When the vehicle speed is greater than the speed threshold, the steering wheel angle is greater than the angle threshold, the accelerator pedal depth is greater than the threshold, and the self-propelled slip angle is greater than the angle threshold, the track mode is activated.

[0189] In another example, when the vehicle steering mode selected by the user is the rotation U-turn mode, it is determined whether the steering wheel angle is greater than a second angle threshold, that is, whether the steering wheel is fully turned. If so, the track mode is activated.

[0190] Step 904 , 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 of the vehicle to output a second torque.

[0191] For details, please refer to the implementation shown in the above step 302. No further details will be given here.

[0192] Step 905: In response to the running operation of the vehicle, exit the steering mode of the vehicle and adjust the current torque of the vehicle at a torque adjustment rate.

[0193] In some embodiments, Fig.11 As shown, the steering control system inputs the current vehicle speed, rear wheel slip rate, rear wheel slip rate, slip change rate, slip change rate, brake pedal depth, steering wheel speed, gear change status, and electronic handbrake status into a state recognition unit to determine the current operating status of the vehicle.

[0194] Furthermore, when the vehicle's operating state changes from a curve state to a curve exit state, the vehicle returns to the activated steering mode and adjusts the vehicle's current torque at the torque adjustment rate.

[0195] The running operation includes at least one of the following: vehicle speed is greater than a preset threshold, brake pedal depth is greater than a depth threshold, steering wheel speed is greater than a speed threshold, gear change, electronic handbrake activation, user turning off steering mode operation, rear wheel slip rate is greater than a slip threshold, rear wheel slip change rate is greater than a change threshold. The rear wheel slip rate may include a slip rate of a first rear wheel and a slip rate of a second rear wheel, and the corresponding rear wheel slip change rate may include a slip change rate of the first rear wheel and a slip change rate of the second rear wheel.

[0196] Exemplarily, when the vehicle satisfies any two or more of the above-mentioned operation conditions, indicating that the vehicle changes from a curve state to an exit state, the vehicle exits the activated steering mode and adjusts the current torque of the vehicle to the driver's required torque at the torque adjustment rate. For example, due to a large change in road adhesion, the actual slip rate of the first rear wheel or the actual slip rate of the second rear wheel is greater than the corresponding threshold, or the change rate thereof is greater than the change threshold, the steering control system exits the activated steering mode.

[0197] It should be noted that the torque adjustment rate is determined by table lookup calculation based on the difference between the current torque and the required torque. It should be understood that when the steering mode is exited or the wheel slip rate / slip rate is uncontrollable, adjusting the vehicle's current torque through the torque adjustment rate can make the vehicle's output torque smooth, reduce the vehicle's frustration caused by torque changes, and improve the driver's driving experience.

[0198] As another example, when the user turns off the steering mode, the user can exit the steering mode by displaying a large screen, using physical buttons, using a voice assistant, etc.

[0199] Optionally, prompt icons such as "Mode Exited" may be displayed on the vehicle's computer and instrument panel to help users understand the current status of the vehicle.

[0200] Based on the above technical solution, the steering control method provided in the embodiment of the present application allows users to select different steering modes according to usage scenarios, and determines whether to activate the steering mode selected by the user according to the current operating status of the vehicle, thereby facilitating subsequent accurate steering control of the vehicle.

[0201] The above mainly introduces the solution provided by the embodiment of the present application from the perspective of the method. In order to achieve the above functions, the steering control system includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0202] The embodiment of the present application can divide the functional modules of the steering control system according to the above method. For example, the steering control system can include functional modules corresponding to the functional divisions, or two or more functions can be integrated into one processing module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. It should be noted that the division of modules in the embodiment of the present application is schematic and is only a logical functional division. There may be other division methods in actual implementation.

[0203] like Fig.12 As shown, the present application provides a schematic diagram of a vehicle steering control device, which includes: a processing unit 1201 and an acquisition unit 1202; the acquisition unit 1202 is used to: acquire a vehicle steering instruction; the processing unit 1201 is used to: respond to the vehicle steering instruction, control 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.

[0204] 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 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.

[0205] In a possible implementation, the processing unit 1201 is specifically configured to: in response to a vehicle steering command, control a first motor corresponding to a first rear wheel to output a first torque to achieve rotation of the first rear wheel, and control a second motor corresponding to a second rear wheel to output a second torque to achieve positive rotation of the second rear wheel. The rotation of the first rear wheel includes positive rotation or reverse rotation.

[0206] In one possible implementation, the first torque is determined in the following manner: obtaining a first actual slip rate and a first target slip rate of the first rear wheel; determining a first slip rate difference and a first difference change rate based on the first actual slip rate and the first target slip rate; the first slip rate difference is the difference between the first target slip rate and the first actual slip rate, and the first difference change rate is the change rate of the first slip rate difference in unit time; and determining the first torque based on the first slip rate difference and the first difference change rate.

[0207] In one possible implementation, the first actual slip rate is determined according to the following method: obtaining the rear axle center point speed of the vehicle; determining the target wheel speed of the first rear wheel based on the rear axle center point speed and the yaw angular velocity of the vehicle; determining the actual slip rate of the first rear wheel based on the target wheel speed of the first rear wheel and the actual wheel speed of the first rear wheel.

[0208] In one possible implementation, the first target slip ratio is determined based on a steering mode of the vehicle and a pre-calibrated slip ratio mapping table, the slip ratio mapping table is used to indicate target slip ratios corresponding to each of a plurality of candidate steering modes of the vehicle, and the steering mode is one of the plurality of candidate steering modes.

[0209] In a possible implementation, the processing unit 1201 is specifically used to: determine a first integral gain coefficient and a first proportional gain coefficient based on the first slip rate difference and the first difference change rate; and perform a PI operation on the first slip rate difference based on the first integral gain coefficient and the first proportional gain coefficient to obtain a first torque.

[0210] In a possible implementation, the second torque is determined by: obtaining a second target slip rate and a second actual slip rate of the second rear wheel; determining a second slip rate difference and a second difference change rate based on the second target slip rate and the second actual slip rate; the second slip rate difference is the difference between the second target slip rate and the second actual slip rate, and the second difference change rate is the change rate of the second slip rate difference in unit time; and determining the second torque based on the second slip rate difference and the second difference change rate.

[0211] In one possible implementation, the second actual slip rate is determined by: acquiring 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 angular velocity of the vehicle; and determining the second actual slip rate based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

[0212] In one possible implementation, 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 ratios corresponding to each of multiple candidate steering modes of the vehicle, and the steering mode is one of the multiple candidate steering modes.

[0213] In one possible implementation, the processing unit 1201 is specifically used to: determine a second integral gain coefficient and a second proportional gain coefficient based on a second slip rate difference and a second difference change rate; and perform a PI operation on the second slip rate difference based on the second integral gain coefficient and the second proportional gain coefficient to obtain a second torque.

[0214] In a possible implementation, the plurality of candidate steering modes include a rotational U-turn mode and a non-rotational U-turn mode, the non-rotational U-turn mode includes a normal mode and a track mode, and a target slip ratio corresponding to the normal mode is smaller than a target slip ratio of the track mode.

[0215] In one possible implementation, the processing unit 1201 is also used to: when the vehicle is in a rotation turn mode, in response to a vehicle steering command, control the braking of the first front wheel of the vehicle and the forward rotation of the second front wheel; wherein the first front wheel is the front wheel of the two front wheels of the vehicle located on the steering side, and the second front wheel is the other front wheel of the two front wheels of the vehicle except the first front wheel.

[0216] In one possible implementation, the processing unit 1201 is also used 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.

[0217] In a possible implementation, the processing unit 1201 is further configured to: when the vehicle is in a non-rotational U-turn mode, in response to a vehicle steering instruction, control both the first front wheel and the second front wheel of the vehicle to rotate forward.

[0218] In a possible implementation, the processing unit 1201 is specifically configured to: in response to a vehicle steering command, control the motor of the first front wheel and the motor of the second front wheel to output a third torque to achieve forward rotation of both the first front wheel and the second front wheel.

[0219] In a possible implementation, the processing unit 1201 is specifically used to determine the third torque based on a first mapping relationship corresponding to an accelerator pedal depth, a motor speed, and a steering mode of the vehicle. The first mapping relationship is a mapping relationship between the accelerator pedal depth, the motor speed, and the third torque; different steering modes correspond to different first mapping relationships.

[0220] In one possible implementation, the processing unit 1201 is also used to: display a steering mode setting interface, the steering mode setting interface including multiple candidate steering modes for the vehicle; and determine the steering mode of the vehicle from the multiple candidate steering modes in response to a user's setting operation on the steering mode setting interface.

[0221] In one possible implementation, the processing unit 1201 is further used to: in response to the operating operation of the vehicle, exit the vehicle-activated steering mode and adjust the current torque of the vehicle at a torque adjustment rate; the torque adjustment rate is determined based on the current torque and the expected torque.

[0222] In one possible implementation, the operating operation includes at least one of the following: vehicle speed is greater than a preset threshold; brake pedal depth is greater than a depth threshold; steering wheel speed is greater than a speed threshold; steering mode operation is turned off; rear wheel slip rate is greater than a slip threshold; rear wheel slip change rate is greater than a change threshold; gear change; electronic handbrake activation.

[0223] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A vehicle steering control method, characterized in that: The method comprises: In response to a vehicle steering command, a first motor corresponding to a first rear wheel of the vehicle is controlled to output a first torque and a second motor corresponding to a second rear wheel of the vehicle is controlled 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 a rear wheel located on a steering side of the vehicle, and the second rear wheel is a rear wheel located on a non-steering side of the vehicle; The first torque is determined by: acquiring a first actual slip rate and a first target slip rate of the first rear wheel; determining a first slip ratio difference and a first difference change rate 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 difference change rate is the change rate of the first slip ratio difference in unit time; The first torque is determined based on the first slip ratio difference and the first difference change rate.

2. The method according to claim 1, characterized in that The method of controlling the first motor corresponding to the vehicle to output the first torque and the second motor corresponding to the second rear wheel to output the second torque in response to the vehicle steering command includes: In response to the vehicle steering command, controlling the first motor corresponding to the first rear wheel to output a first torque to achieve rotation of the first rear wheel, and controlling the second motor corresponding to the second rear wheel to output a second torque to achieve positive rotation of the second rear wheel; The rotation of the first rear wheel includes forward rotation or reverse rotation.

3. The method according to claim 1, characterized in that The first actual slip ratio is determined according to the following method: Obtaining the rear axle center point speed of the vehicle; Determining a target wheel speed of the first rear wheel based on the rear axle center point speed and the yaw rate of the vehicle; An actual slip ratio of the first rear wheel is determined based on the target wheel speed of the first rear wheel and the actual wheel speed of the first rear wheel.

4. The method according to claim 1, characterized in that: The first target slip ratio is determined based on a steering mode of the vehicle and a pre-calibrated slip ratio mapping table, wherein the slip ratio mapping table is used to indicate target slip ratios corresponding to each of a plurality of candidate steering modes of the vehicle, and the steering mode is one of the plurality of candidate steering modes.

5. The method according to any one of claims 1 to 4, characterized in that: The determining the first torque based on the first slip ratio difference and the first difference change rate includes: determining a first integral gain coefficient and a first proportional gain coefficient based on the first slip ratio difference and the first difference change rate; Based on the first integral gain coefficient and the first proportional gain coefficient, a PI operation is performed on the first slip ratio difference to obtain the first torque.

6. The method according to claim 2, characterized in that The second torque is determined by: acquiring a second target slip rate and a second actual slip rate of the second rear wheel; determining a second slip ratio difference and a second difference change rate based on the second target slip ratio and the second actual slip ratio; The second slip rate difference is the difference between the second target slip rate and the second actual slip rate, and the second difference change rate is the change rate of the second slip rate difference in unit time; The second torque is determined based on the second slip difference and the second difference change rate.

7. The method according to claim 6, characterized in that The second actual slip ratio is determined by: Obtaining the rear axle center point speed of the vehicle; determining a target wheel speed of the second rear wheel based on the rear axle center point speed and the yaw rate of the vehicle; The second actual slip ratio is determined based on the target wheel speed of the second rear wheel and the actual wheel speed of the second rear wheel.

8. The method according to claim 6, characterized in that The second target slip rate is determined based on a steering mode of the vehicle and a pre-calibrated slip rate mapping table; the slip rate mapping table is used to indicate target slip rates corresponding to each of a plurality of candidate steering modes of the vehicle, and the steering mode is one of the plurality of candidate steering modes.

9. The method according to any one of claims 6 to 8, characterized in that: The determining the second torque based on the second slip ratio difference and the second difference change rate includes: determining a second integral gain coefficient and a second proportional gain coefficient based on the second slip rate difference and the second difference change rate; Based on the second integral gain coefficient and the second proportional gain coefficient, a PI operation is performed on the second slip ratio difference to obtain the second torque.

10. The method according to claim 4 or 8, characterized in that: The plurality of candidate steering modes include a rotational U-turn mode and a non-rotational U-turn mode, the non-rotational U-turn mode includes a normal mode and a track mode, and a target slip ratio corresponding to the normal mode is smaller than a target slip ratio of the track mode.

11. The method according to claim 1, characterized in that: The method further comprises: When the vehicle is in a rotation turn mode, in response to a vehicle steering command, the first front wheel of the vehicle is braked and the second front wheel is rotated forward; 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 except the first front wheel.

12. The method according to claim 11, characterized in that When the vehicle is in a rotation turn mode, in response to a vehicle steering instruction, controlling the first front wheel of the vehicle to brake and the second front wheel to rotate forwardly comprises: 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 positive rotation of the second front wheel.

13. The method according to claim 11, characterized in that The method further comprises: When the vehicle is in a non-rotation U-turn mode, in response to a vehicle steering command, both the first front wheel and the second front wheel of the vehicle are controlled to rotate forward.

14. The method according to claim 13, characterized in that When the vehicle is in a non-rotation U-turn mode, in response to a vehicle steering instruction, controlling both the first front wheel and the second front wheel of the vehicle to rotate forwardly comprises: In response to the vehicle steering command, the motor of the first front wheel and the motor of the second front wheel are controlled to output a third torque to achieve positive rotation of the first front wheel and the second front wheel.

15. The method according to claim 12 or 14, characterized in that The method further comprises: Determining the third torque based on a first mapping relationship corresponding to an accelerator pedal depth, a motor speed, and a steering mode of the vehicle; The first mapping relationship is a mapping relationship among the accelerator pedal depth, the motor speed and the third torque; different steering modes correspond to different first mapping relationships.

16. The method according to claim 1, characterized in that The method further comprises: displaying a steering mode setting interface, wherein the steering mode setting interface includes a plurality of candidate steering modes for the vehicle; In response to a setting operation of a user on a steering mode setting interface, a steering mode of the vehicle is determined from the plurality of candidate steering modes.

17. The method according to claim 16, characterized in that The method further comprises: In response to an operating operation of the vehicle, an activated steering mode of the vehicle is exited and a current torque of the vehicle is adjusted at a torque adjustment rate; the torque adjustment rate is determined based on the current torque and a desired torque.

18. The method according to claim 17, characterized in that The operation includes at least one of the following: The vehicle speed is greater than the preset threshold; The brake pedal depth is greater than the depth threshold; The steering wheel speed is greater than the speed threshold; Turn off the steering mode operation; The rear wheel slip rate is greater than the slip threshold; The rear wheel slip change rate is greater than the change threshold; Gear changes; The electronic parking brake is activated.

19. A vehicle steering control device, characterized in that: The device comprises: a processing unit; The processing unit is used to 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 in response to a vehicle steering command; wherein the torque direction of the first torque is reverse, the torque direction of the second torque is forward, the first rear wheel is a rear wheel located on a steering side of the two rear wheels of the vehicle, and the second rear wheel is another rear wheel of the two rear wheels of the vehicle except the first rear wheel; The first torque is determined by: acquiring a first actual slip rate and a first target slip rate of the first rear wheel; determining a first slip ratio difference and a first difference change rate 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 difference change rate is the change rate of the first slip ratio difference in unit time; The first torque is determined based on the first slip ratio difference and the first difference change rate.

20. A vehicle, characterized in that: include: 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 method according to any one of claims 1 to 18.

21. A computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, characterized in that: When a computer executes the instruction, the computer performs the method according to any one of claims 1 to 18.

22. A computer program product, comprising instructions, wherein when the instructions are executed on a computer, The computer executes the method according to any one of claims 1 to 18 above.

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