Vehicle steering method, device and vehicle

Abstract

The application provides a vehicle steering method, device and vehicle. The method comprises: braking a second group of tires so that the second group of tires is in a non-rotating state; driving a first group of tires, each tire in the first group of tires corresponding to a driving force with the same torque direction; in a case where the driving force for driving the first group of tires is greater than the tire adhesion of the first group of tires and the steering angle of the first group of tires is greater than a first steering angle, controlling vehicle steering based on the driving force and the steering angle of the first group of tires. The vehicle passing performance in the steering working condition is improved while the minimum turning radius of the vehicle is reduced.

Description

A vehicle steering method, device, and vehicle Technical Field

[0001] This application relates to the field of vehicles, and more particularly to a vehicle steering method, device, and vehicle. Background Technology

[0002] Generally, when a car's steering wheel is turned to its limit and the car is turning at a relatively low, stable speed, the radius of the circle traced by the center plane of the outer steering wheel on the supporting plane is called the car's minimum turning radius. The smaller the minimum turning radius, the better the vehicle's handling in turning situations.

[0003] In some vehicle steering methods, all four wheels of the car are used as steering wheels. Steering motors control the steering angle of all four wheels to their maximum angle, and hub motors drive the vehicle. This allows for steering with a very small turning radius, enabling the vehicle to turn on the spot or make a U-turn. However, this method requires all four wheels to be steerable and needs to be used in conjunction with hub motors, which significantly limits its practical application.

[0004] Therefore, how to improve vehicle passability during cornering while reducing the turning radius of a car has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This application provides a vehicle steering method, device, and vehicle that improves vehicle passability during cornering while reducing the turning radius of the vehicle.

[0006] In a first aspect, this application provides a vehicle steering method applied to a vehicle, the vehicle including a first set of tires and a second set of tires, wherein the first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel, the method including: braking the second set of tires so that the second set of tires is in a non-rotating state; driving the first set of tires, wherein the torque direction of the driving force corresponding to each tire in the first set of tires is the same; and controlling the vehicle steering based on the driving force and the steering angle of the first set of tires when the driving force driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than a first steering angle, wherein the steering angle of the first set of tires is the angle between the first set of tires and the vehicle body.

[0007] In this embodiment, when the driving force of the first set of tires is greater than the tire adhesion of the first set of tires, the driving force of the first set of tires causes the first set of tires to slip. The dynamic friction generated by the tire slippage provides longitudinal traction for the vehicle, so that the vehicle can turn with a smaller turning radius based on the lateral traction provided by the first set of tires. That is, the vehicle steering method provided by this application reduces the turning radius of the car while improving the vehicle passability in turning conditions.

[0008] In some possible implementations, before driving the first set of tires, the method further includes: acquiring the vehicle's gear information, the gear information including forward gear and reverse gear; acquiring throttle depth information; driving the first set of tires includes: controlling the vehicle's motor to output corresponding torque magnitude and torque direction based on the throttle depth information and the gear information, so as to drive the first set of tires.

[0009] In some possible implementations, the method further includes: when the driving force output by the motor used to drive the first set of tires after reaching the peak motor torque is still less than or equal to the tire adhesion of the first set of tires and the vehicle is stationary, outputting first indication information and controlling the vehicle to exit steering control, wherein the first indication information is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for steering the vehicle using the steering control method.

[0010] In some possible implementations, braking the second set of tires includes: applying braking force to brake the left rear wheel and the right rear wheel respectively, wherein the braking force is greater than or equal to the tire adhesion force corresponding to one of the tires in the second set of tires, the second set of tires including the left rear wheel and the right rear wheel.

[0011] In some possible implementations, before controlling the vehicle steering based on the driving force and the steering angle of the first set of tires when the driving force driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than the first steering angle, the method further includes: determining the steering angle of the first set of tires based on the rotation angle of the steering wheel obtained by the angle sensor in the steering mechanism.

[0012] In some possible implementations, the peak torque of the motor corresponding to the first set of tires is greater than a first value, which is determined based on the tire adhesion of the first set of tires, the speed ratio of the vehicle reducer, and the tire radius of the first set of tires.

[0013] In some possible implementations, the first distance between the center of gravity of the vehicle and the center of the first set of tires is greater than the second distance between the center of gravity of the vehicle and the center of the second set of tires.

[0014] In some possible implementations, before the vehicle enters the steering control mode, the method further includes: obtaining the maximum mass that the motor corresponding to the first set of tires can drive, the maximum mass being related to the maximum driving force corresponding to the peak torque of the motor; obtaining the total mass of the vehicle, the total mass including the vehicle's curb weight and the mass of the objects actually carried by the vehicle; and controlling the vehicle to enter the steering control mode in response to user input of operation information indicating that the vehicle should enter the steering control mode, including: if the maximum mass is greater than the total mass, the vehicle enters the steering control mode in response to user input of operation information indicating that the vehicle should enter the steering control mode.

[0015] In some possible implementations, the method further includes: when the maximum mass is less than the vehicle's curb weight, in response to user-inputted operation information indicating that the vehicle is not capable of entering the steering control mode, outputting second indication information, the second indication information indicating that the vehicle's performance does not support entering the steering control mode; when the maximum mass is greater than the vehicle's curb weight but less than the total mass, in response to user-inputted operation information indicating that the vehicle is capable of entering the steering control mode, outputting third indication information, the third indication information indicating that the mass of the object carried by the vehicle exceeds the maximum mass for the vehicle to enter the steering control mode.

[0016] In some possible implementations, the method further includes: when the driving force of the first set of tires is less than or equal to the tire adhesion of the first set of tires, or when the steering angle of the first set of tires is less than a first steering angle, the vehicle remains stationary or the distance the vehicle travels is small.

[0017] Secondly, this application provides a vehicle steering device, comprising: a braking unit for braking a second set of tires so that the second set of tires is in a non-rotating state; a driving unit for driving a first set of tires; and a control unit for controlling the vehicle steering based on the driving force and the steering angle of the first set of tires when the driving force of the driving unit driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than a first steering angle, wherein the steering angle of the first set of tires is the angle between the first set of tires and the vehicle body, and the first set of tires are front wheels and the second set of tires are rear wheels, or the first set of tires are rear wheels and the second set of tires are front wheels.

[0018] Thirdly, this application provides a vehicle, the vehicle including a controller, a motor controller, a brake controller, a first set of tires, and a second set of tires, wherein the first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel, the controller being used to request the brake controller to brake the second set of tires and to request the motor control unit to drive the first set of tires, so as to realize the above-mentioned vehicle steering method and realize vehicle steering.

[0019] Fourthly, this application provides a vehicle steering system, the system including a steering control unit, a first set of tires, a second set of tires, a braking force control unit, a motor controller, a motor, and a steering mechanism, wherein the first set of tires are front wheels and the second set of tires are rear wheels, or the first set of tires are rear wheels and the second set of tires are front wheels; the steering control unit is configured to request the braking force control unit to brake the second set of tires, so that the second set of tires is in a non-rotating state; the steering mechanism is configured to change the steering angle of the first set of tires; the steering control unit is configured to request the motor controller to control the output torque of the motor, so that the motor drives the first set of tires; the steering control unit is further configured to control the vehicle to steer when the steering angle of the first set of tires is greater than a first steering angle and the driving force output by the motor is greater than the tire adhesion of the first set of tires.

[0020] In some possible implementations, the system further includes a steering control mode request input device and an in-vehicle network. The steering control mode request input device is used to receive user input requesting to enter the steering control mode. The steering control unit is specifically used to respond to the user input request to enter the steering control mode, determine to enter the steering control mode, and brake the second set of tires through the braking force control unit based on the steering control mode, so that the second set of tires is in a non-rotating state. The steering control unit is also used to obtain throttle depth and gear status based on the in-vehicle network, and determine the magnitude of the motor torque output by the motor controller based on the throttle depth, and determine the direction of the motor torque output by the motor controller based on the gear status. The steering control unit is also used to request the motor controller to control the motor to output torque corresponding to the magnitude and direction of the motor torque. The steering mechanism is specifically used to determine the steering angle of the first set of tires based on the steering wheel rotation angle obtained by the angle sensor. The motor controller is specifically used to control the motor to output torque corresponding to the motor torque direction and magnitude requested by the steering control unit, so as to drive the first set of tires.

[0021] It is understood that the vehicle steering system provided in the second aspect, the vehicle steering transpose provided in the third aspect, and the vehicle provided in the fourth aspect are all used to execute the vehicle steering method shown in the first aspect or any implementation thereof of the embodiments of this application. Therefore, the beneficial effects they can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below.

[0023] Figure 1 is a schematic flowchart of a vehicle steering method provided in an embodiment of this application;

[0024] Figure 2 is a flowchart illustrating another vehicle steering method provided in an embodiment of this application;

[0025] Figure 3 is a structural schematic diagram of a vehicle steering system provided in an embodiment of this application;

[0026] Figure 4 is a structural schematic diagram of a vehicle steering device provided in an embodiment of this application;

[0027] Figure 5 is a structural schematic diagram of another vehicle steering device provided in an embodiment of this application;

[0028] Figure 6 is a structural schematic diagram of an electro-hydraulic braking system provided in an embodiment of this application;

[0029] Figure 7 is a structural schematic diagram of a vehicle provided in an embodiment of this application. Detailed Implementation

[0030] The present application will now be described in further detail with reference to the accompanying drawings.

[0031] The terminology used in the following embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to include the plural expressions as well, unless the context clearly indicates otherwise.

[0032] In this application, "at least one (item)" means one or more, "more than one" means two or more, "at least two (items)" means two or three or more, and "and / or" is used to describe the relationship between related objects, indicating that there can be three relationships. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items. For example, at least one (item) of a, b, or c can mean: a, b, c, "a and b", "a and c", "b and c", or "a and b and c".

[0033] The following describes a vehicle steering method provided by an embodiment of this application, with reference to Figure 1.

[0034] In the embodiments of this application, the vehicle to which the vehicle steering method is applied includes a first set of tires and a second set of tires, wherein the first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel.

[0035] In the embodiments of this application, the executing entity of the vehicle steering method may be the vehicle provided in this application, the controller in the vehicle, or the steering control unit in the vehicle, or it may be executed by various units in the vehicle steering system provided in this application in cooperation. This document does not limit the execution entity. For ease of description, the vehicle steering methods shown in Figures 1 and 2 below omit the relevant descriptions of the executing entity.

[0036] As shown in Figure 1, the vehicle steering method includes the following steps:

[0037] S101, brake the second set of tires so that the second set of tires is in a non-rotating state.

[0038] In the embodiments of this application, the second group of tires includes at least one tire. It should be noted that when the number of tires in the second group of tires is greater than or equal to 2, braking the second group of tires means braking each tire in the second group of tires.

[0039] Specifically, the second set of tires is braked so that the braking force of the second set of tires reaches the maximum design value to keep the second set of tires in a non-rotating state, which can also be understood as a locked state.

[0040] For example, the braking force of the second set of tires is greater than or equal to the tire adhesion force corresponding to the second set of tires, so that the braking force of the second set of tires reaches its maximum design value. It should be noted that the effective braking force of the second set of tires is provided by the tire adhesion force; therefore, the maximum effective braking force of the second set of tires is the tire adhesion force of the second set of tires. For ease of description, the tire adhesion force corresponding to the second set of tires will be referred to as the second adhesion force.

[0041] The second adhesion force is related to the vehicle's total mass (including the vehicle's curb weight and the mass of the load), gravitational acceleration, ground adhesion coefficient, the distance between the center of the second set of tires and the vehicle's center of gravity, and the distance between the center of the first set of tires and the vehicle's center of gravity. As an example, when the first set of tires includes the left and right front wheels connected by the front axle, and the second set of tires includes the left and right rear wheels connected by the rear axle, the distance between the center of the first set of tires and the vehicle's center of gravity is the same as the distance between the center of the front axle and the vehicle's center of gravity, and the distance between the center of the second set of tires and the vehicle's center of gravity is the same as the distance between the center of the rear axle and the vehicle's center of gravity. The vehicle's center of gravity refers to the center of the vehicle's curb weight when the vehicle is unloaded on a level, flat surface.

[0042] As an example, we can assume that the mass of the object carried by the vehicle is a preset mass. For example, this preset mass could be a preset single-person mass (i.e., the mass of the driver alone), and could be any mass value greater than or equal to 75 kg and less than or equal to 100 kg. Alternatively, the preset mass could be a preset full-load mass (i.e., the full-load mass of the vehicle). Based on this preset mass, the maximum value of the second adhesion force can be determined. Then, based on this maximum value of the second adhesion force, the minimum braking force output by the vehicle can be determined, and the correlation coefficient of the corresponding braking control device for the vehicle can be designed based on this minimum braking force.

[0043] In this scenario, where the braking force control unit in the vehicle independently controls the braking of each tire in the second group of tires, the braking force applied to each tire in the second group is greater than or equal to the tire adhesion force of that tire. For example, if the second group of tires includes a left rear wheel and a right rear wheel, the braking force applied to the left rear wheel is greater than or equal to the tire adhesion force of that left rear wheel, and the braking force applied to the right rear wheel is greater than or equal to the tire adhesion force of that right rear wheel.

[0044] In some possible implementations, before braking the second set of tires, the method further includes: controlling the vehicle to enter a steering control mode in response to user-inputted operational information instructing the vehicle to enter a steering control mode. Braking the second set of tires includes: braking the second set of tires based on the steering control mode.

[0045] In one possible implementation, the braking force control device for braking the second set of tires can be an electro-hydraulic braking system or an electronic parking brake system.

[0046] S102, drives the first set of tires.

[0047] In this embodiment, the first group of tires includes at least one tire, and the number of tires in the first group is less than or equal to the number of tires in the second group. Preferably, the number of tires in the first group is equal to the number of tires in the second group. If the number of tires in the first group is less than the number of tires in the second group, the difference in the number of tires should not be too large. It should be noted that when the number of tires in the first group is greater than or equal to two, driving the first group means driving each tire in the first group.

[0048] In this embodiment, when the first group of tires contains two or more tires, the driving method for the first group of tires can be a single-motor or multi-motor driving method. In the single-motor driving method, the motor driving each tire in the first group of tires is the same motor; in the multi-motor driving method, the motors driving every two tires in the first group of tires can be different. Furthermore, in this embodiment, the driving torque direction of each tire in the first group of tires is the same.

[0049] As an example, the first set of tires includes a left front wheel and a right front wheel, which are connected by a front axle. In a single-motor drive mode, the motor can be used to drive the front axle. By driving the front axle with the motor, the left and right front wheels can be driven, and the direction and magnitude of the driving torque of each tire in the first set of tires can be the same.

[0050] In some possible implementations, the vehicle also includes an accelerator and gears. Before step S102, the vehicle steering method provided in this application further includes: obtaining vehicle gear information based on user operation information regarding the gears, the gear information including forward gears and reverse gears; and obtaining throttle depth information based on user operation information regarding the accelerator. Step S102, driving the first set of tires, specifically includes: controlling the motor of the first set of tires to output corresponding torque magnitude and torque direction based on the throttle depth information and the gear information, so as to drive the first set of tires.

[0051] S103, when the driving force driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than the first steering angle, the vehicle steering is controlled based on the driving force and the steering angle of the first set of tires.

[0052] In this embodiment, when the driving force of the first set of tires is greater than the tire adhesion of the first set of tires, the driving force of the first set of tires causes the first set of tires to slip. The dynamic friction generated by the tire slippage provides longitudinal traction for the vehicle, while the static friction generated by the locking of the second set of tires provides longitudinal braking force for the vehicle. When the adhesion coefficients of the tires are similar for the same vehicle, the dynamic friction is less than the static friction, meaning the longitudinal braking force cannot cause the vehicle to move longitudinally. However, when the first set of tires slips and the steering angle of the first set of tires is greater than the first steering angle, the first set of tires provides lateral force to the vehicle, i.e., generates a yaw moment, while the second set of tires is not rotating. The lateral force generated by the second set of tires that can suppress this yaw moment is very small, thus the vehicle can turn with a small turning radius based on the lateral force provided by the first set of tires.

[0053] Furthermore, the vehicle steering method provided in this application requires that the first set of tires be both drive wheels and steering wheels, and the second set of tires be brake wheels. This requirement can be met by most vehicles, such as front-wheel drive vehicles with front-wheel steering, rear-wheel drive vehicles with rear-wheel steering, and four-wheel drive vehicles with front-wheel steering and / or rear-wheel steering. Thus, the vehicle steering method provided in this application can reduce the minimum turning radius of the vehicle while improving the vehicle's passability in turning conditions.

[0054] There are three other methods for vehicle steering that reduce the turning radius of a vehicle.

[0055] The first method is to modify the vehicle's drive system so that the driving force of the inner wheels is opposite to that of the outer wheels when turning. For example, by rigidly connecting the steering wheels to the front axle drive mechanism, the wheels on both sides rotate in opposite directions to achieve a turn on the spot in a manner similar to track turning.

[0056] The second method is to modify the vehicle's steering system so that all four wheels can steer. For example, a steering motor controls the turning angle of all four wheels, while hub motors control the driving force to allow the vehicle to turn with a smaller radius. This method requires adding a steering drive unit to convert the rear wheels into steering wheels, and the required steering angle is relatively large. It often needs to be used in conjunction with hub motors, which is quite limiting in practice.

[0057] The third method involves installing a stationary steering device on the vehicle's floor. When turning in place, this device first lifts the vehicle until all four wheels are off the ground. Then, the device itself turns the vehicle, or it drives the platform supporting the vehicle to rotate relative to the ground, thus turning the vehicle. Finally, the vehicle is lowered back to the ground. For example, a support plate is placed on the ground as a fulcrum, a telescopic cylinder lifts the vehicle, and a motor drives the vehicle to rotate relative to the support plate, thereby achieving steering. This method requires adding a new device to the vehicle chassis, which not only increases the vehicle's curb weight but also reduces its ground clearance, lowering its passability. It is more suitable as a temporary rescue tool than as a long-term component to be installed on the vehicle.

[0058] The three methods for reducing a vehicle's turning radius all require adding components to the original vehicle structure or making significant modifications to the existing drive or steering system, which limits their practical application and versatility. However, the steering method provided in this application only requires the vehicle's hardware to include the first set of tires being both steering and drive wheels, and the second set of tires being brake wheels—requirements that most cars can meet. Furthermore, the steering method provided in this application ensures that the second set of tires does not rotate and that the first set of tires slips, resulting in a very small longitudinal movement distance for the vehicle. This leads to a smaller turning radius, thus improving the vehicle's passability during cornering while simultaneously reducing the turning radius.

[0059] Specifically, compared with the three other vehicle steering methods mentioned above, the advantages of the vehicle steering method provided in this application include:

[0060] 1) The system is simple and easy to implement. The vehicle steering method provided in this application requires minimal design modifications to the original vehicle. Its components are all derived from common drive systems, steering systems, and braking systems found in existing ordinary vehicles, without the need to add any new components.

[0061] The reason is that this application achieves vehicle steering by using coordinated control to cause the first set of tires to slip when the second set of tires brakes and does not rotate. This suppresses the longitudinal movement of the entire vehicle while generating a yaw moment using the lateral force of the front axle, thus achieving vehicle steering without the need for additional components. On surfaces with low coefficient of friction, such as ice, the motor's driving force is sufficient to exceed the tire's adhesion and cause slippage, essentially eliminating the need to increase the motor torque to the design value corresponding to the maximum driving force. To prevent frequent slippage of the first set of tires on conventional concrete surfaces with low coefficient of friction in front-wheel-drive electric vehicles, the maximum driving force of the front axle is generally designed to be slightly lower than the maximum adhesion force of the front axle at that coefficient of friction. If this application is to be applied to conventional road conditions with high coefficient of friction, the design value of the maximum driving force of the front axle must be increased. This can be achieved by increasing the peak torque of the motor or increasing the gear ratio of the reducer, which is easier to implement than changing the drive system to a distributed drive system or altering the steering system.

[0062] 2) The control method is simple, reliable, and easy for drivers to master. During control, after the driver turns the steering wheel to a certain angle, the motor outputs torque linearly through the throttle input. When the first set of tires begins to slip, the vehicle continues to steer. If the throttle is released and the first set of tires stops slipping, the vehicle quickly returns to a stationary state. The control method is simple and reliable, and the process conforms to the operating habits of ordinary drivers, making it easy for them to master. If the driver encounters an emergency and needs to stop steering, they only need to release the throttle; the emergency handling method perfectly matches the driver's intuitive reaction.

[0063] 3) It combines the characteristics of two extreme working conditions: the second group of tires not turning when braking and the first group of tires slipping when driving. This allows ordinary drivers to easily master the same stationary drifting skills as professional race car drivers. The control process is accompanied by the "squeaking" and "burning" effects of the tires slipping when driving, allowing ordinary drivers to experience the atmosphere and fun of drifting.

[0064] This application allows for changing the vehicle's heading angle in extremely confined spaces, enabling convenient entry and exit from parking spaces and greatly improving the vehicle's convenience in extreme parking conditions.

[0065] In some possible implementations, the steering wheel rotation angle can be obtained based on the angle sensor in the steering mechanism included in the vehicle, and the steering angle of the first set of tires can be determined based on the steering wheel rotation angle.

[0066] In the embodiments of this application, the first steering angle is greater than 0; for example, the first steering angle is 20°. The specific value of the first steering angle can be determined based on the critical steering angle at which the vehicle executes the vehicle steering method provided in this application to achieve steering under different experimental conditions (specifically, different vehicle performance conditions, different road conditions, etc.), and is not limited herein.

[0067] It should be noted that the steering angle of each tire in the first group of tires can be the same or have a certain margin of error. "The steering angle of the first group of tires is greater than the first steering angle" can mean that the steering angle of one or more tires in the first group is greater than the first steering angle, or that the average of the steering angles of all tires in the first group is greater than the first steering angle. For example, if the first group of tires includes the left front wheel and the right front wheel, "The steering angle of the first group of tires is greater than the first steering angle" could mean that the steering angle of the left front wheel is greater than the first steering angle, or it could mean that the steering angle of the right front wheel is greater than the first steering angle, or it could mean that the average of the sum of the steering angles of the left and right front wheels is greater than the first steering angle. This article does not impose any limitations on this.

[0068] In this embodiment of the application, by combining the vehicle's throttle depth information, gear information, and the steering angle of the first set of tires, the direction of vehicle steering can be left front, right front, right rear, or left rear.

[0069] For ease of description, the tire adhesion of the first group of tires will be referred to as the first adhesion.

[0070] In some possible implementations, to ensure that the driving force is greater than the first adhesion force, the vehicle performance requirements include: the peak torque of the motor corresponding to the first set of tires is greater than a first value. This first value is determined based on the reducer ratio, the tire adhesion force of the first set of tires, and the tire radius. This can also be understood as the maximum driving force provided by the motor corresponding to the first set of tires to the first set of tires being greater than the first adhesion force.

[0071] In this embodiment of the application, the peak torque of the motor corresponding to the first set of tires is greater than the first value. This is to meet the performance requirements of the motor corresponding to the first set of tires. The peak torque of the motor meeting the performance requirements can make the driving force greater than the tire adhesion of the first set of tires, causing the first set of tires to slip.

[0072] As an example, we can assume that the mass of the object carried by the vehicle is a preset mass, such as the preset mass of a single person or the preset full load mass. Then, based on this preset mass, the maximum value of the first adhesion force can be determined. Based on the maximum value of the first adhesion force, the minimum value that the maximum driving force output by the motor needs to satisfy can be determined. And based on the minimum value that the maximum driving force needs to satisfy, the lower limit of the maximum output torque of the motor can be designed.

[0073] It should be noted that while meeting the performance requirements of the vehicle's motor peak torque can enable the driving force to be greater than the first adhesion force, it is not only the case that the peak torque of the vehicle's motor meets the performance requirements that enables the driving force to be greater than the first adhesion force. Other conditions can also enable the driving force to be greater than the first adhesion force. For example, making the ground contacted by the first set of tire locks smoother will reduce the coefficient of friction and the first adhesion force, thus making the driving force greater than the first adhesion force.

[0074] In this embodiment, when the driving force of the first set of tires exceeds the first adhesion force, the first set of tires slips. The longitudinal traction force generated by the driving force on the vehicle is very small, far less than the longitudinal braking force provided by the second set of tires to prevent the vehicle from moving longitudinally. Therefore, the longitudinal driving force generated by the motor is almost unable to cause the vehicle to move longitudinally. However, based on the driving force being greater than the first adhesion force and the steering angle of the first set of tires being greater than 0, the vehicle generates lateral traction force. Since the second set of tires is not rotating, it almost loses its ability to output lateral force. For example, if the lateral traction force generated by the driving force is 100 N, the lateral restraining force generated by the second set of tires is 51 N. Thus, the vehicle can make a turn with a small radius based on this lateral traction force, and the vehicle makes a yaw motion that is almost like turning in place. The specific value of the turning radius is determined based on the changes in the vehicle's correlation coefficient. For example, the turning radius is related to the size of the first steering angle and the distance between the centers of the first set of tires and the centers of the second set of tires.

[0075] In this embodiment, before the driving force of the first set of tires increases to the point that the first set of tires slips (i.e., the driving force of the first set of tires is less than or equal to the tire adhesion of the first set of tires), if the driving force can overcome the longitudinal braking force of the second set of tires (the maximum effective longitudinal braking force of the second set of tires is equal to the tire adhesion of the second set of tires), the driving force can propel the vehicle forward longitudinally. However, since the tire adhesion of the first set of tires and the tire adhesion of the second set of tires are generally not much different, when the driving force is less than or equal to the tire adhesion of the first set of tires, the driving force is generally also less than the tire adhesion of the second set of tires. Therefore, before the driving force of the first set of tires increases to the point that the first set of tires slips, the distance the vehicle moves is almost zero or small.

[0076] However, assuming the first distance from the vehicle's center of gravity to the center of the first set of tires is equal to the second distance from the vehicle's center of gravity to the center of the second set of tires, and the ground adhesion coefficients corresponding to the first and second sets of tires are the same, then under the same load-bearing mass, the tire adhesion of the first set of tires is equal to the tire adhesion of the second set of tires. However, when implementing the vehicle steering method provided in this application, users generally only have passengers in the driver's and passenger's seats. Therefore, the load-bearing mass corresponding to the first set of tires will be greater than that of the second set of tires, and the tire adhesion of the first set of tires will be greater than that of the second set of tires. Thus, before the driving force increases to exceed the tire adhesion of the first set of tires, the driving force will first exceed the tire adhesion of the second set of tires, causing the vehicle to move.

[0077] In view of this, in some possible implementations of this application, the first distance is designed to be slightly larger than the second distance, so that when the load of the first set of tires is greater than the load of the second set of tires, the tire adhesion of the second set of tires is greater than or equal to the tire adhesion of the first set of tires, effectively preventing the vehicle from moving after the driving force of the first set of tires increases to be greater than the tire adhesion of the second set of tires but before it is less than the tire adhesion of the second set of tires.

[0078] The first distance is only slightly larger than the second distance to avoid the vehicle overturning due to an excessively large first distance and an excessively small second distance. For example, suppose the first distance is 'a' and the second distance is 'b', where 'b' is greater than or equal to a first preset multiple, which is less than 1 and greater than or equal to 0.95. For instance, 'b' is greater than or equal to 0.95a and less than or equal to 0.999a.

[0079] It should be noted that the method of making the tire adhesion of the second group of tires greater than or equal to that of the first group of tires by making the first group of tires greater than or equal to that of the second group of tires is only an example. Other methods can also be used to make the tire adhesion of the second group of tires greater than or equal to that of the first group of tires. This article does not limit this method, for example, by making the ground adhesion coefficient of the second group of tires greater than that of the first group of tires.

[0080] In some possible implementations, the method shown in Figure 1 further includes: when the driving force output by the motor used to drive the first set of tires is still less than or equal to the tire adhesion of the first set of tires after the motor reaches its peak torque, and the vehicle is stationary, outputting first indication information and controlling the vehicle to exit steering control, wherein the first indication information is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for vehicle steering using the vehicle steering method.

[0081] In this embodiment of the application, when the driving force output by the motor after reaching the peak torque is still less than or equal to the tire adhesion of the first set of tires, the above-mentioned first indication information is output, which can provide users with guidance on the correct use of the vehicle steering method provided in this application, enhance user interaction, and improve user experience.

[0082] In some possible implementations, after receiving user input indicating that the vehicle should enter the steering control mode, and before the vehicle enters the steering control mode, the method further includes: obtaining the maximum mass that the motor corresponding to the first set of tires can drive, the maximum mass being related to the maximum driving force corresponding to the peak torque of the motor (a parameter set at the factory); and obtaining the real-time total mass of the vehicle, the total mass including the vehicle's curb weight and the mass of the actual load carried by the vehicle, wherein the mass of the actual load carried by the vehicle can be determined by adding a height sensor to the vehicle's suspension and combining it with known suspension stiffness; the above-mentioned response to user input indicating that the vehicle should enter the steering control mode, controlling the vehicle to enter the steering control mode, includes: when the maximum mass is greater than the total mass, responding to user input indicating that the vehicle should enter the steering control mode, controlling the vehicle to enter the steering control mode.

[0083] In some possible implementations, the method further includes: when the maximum mass is less than the vehicle's curb weight, in response to user input of operation information indicating that the vehicle should enter the steering control mode, outputting second indication information, the third indication information indicating that the vehicle's performance does not support entering the steering control mode (i.e., it does not support the steering method provided in this application to steer the vehicle); when the maximum mass is greater than the vehicle's curb weight but less than the total mass, in response to user input of operation information indicating that the vehicle should enter the steering control mode, outputting third indication information, the third indication information indicating that the mass of the object carried by the vehicle exceeds the maximum mass for entering the steering control mode (i.e., the vehicle cannot steer the vehicle by executing the steering method provided in this application due to the excessive weight of the object carried).

[0084] Referring to Figure 2, the following describes an application of the vehicle steering method provided in this application, using the following example: the first set of tires includes a left front wheel and a right front wheel connected via the front axle; the second set of tires includes a left rear wheel and a right rear wheel connected via the rear axle; the left and right front wheels are driven by a single motor (specifically, the left and right front wheels are driven by a first motor driving the front axle); and the vehicle's braking control unit independently controls the braking of the left and right rear wheels. For ease of description, "front wheel" refers to the left and right front wheels, and "rear wheel" refers to the left and right rear wheels.

[0085] As shown in Figure 2, the vehicle steering method includes:

[0086] S201, Received a request from the driver to enter the steering control mode.

[0087] In this embodiment of the application, the steering control mode may also be called a steering mode with a smaller turning radius or other suitable names, and the specific name of the steering control mode is not limited.

[0088] S202, determine whether the first preset condition for entering the steering control mode is met.

[0089] In this embodiment, the first preset condition may include, but is not limited to, one or more of the following: the vehicle is in P gear (park), the vehicle has sufficient power (e.g., sufficient fuel, sufficient battery power, etc.), and the vehicle's components are in normal working order (no malfunction). When the vehicle meets each of the first preset conditions, it is determined that the vehicle meets the first preset condition for entering the steering control mode.

[0090] If the first preset condition for entering the steering control mode is met, proceed to step S203; if the first preset condition for entering the steering control mode is not met, return to S201 and wait for the next time the driver requests to enter the steering control mode.

[0091] In some possible implementations, if it is determined that the first preset condition for entering the steering control mode is not met, a third prompt message can also be output. This third prompt message indicates the specific reason why the steering control mode cannot be entered. For example, if insufficient vehicle power causes the inability to enter the steering control mode, the third prompt message indicates that the reason for not entering the steering control mode is insufficient vehicle power.

[0092] S203, brake the rear wheel.

[0093] For example, if a first preset condition for entering the steering control mode is met, the vehicle is controlled to enter the steering control mode, and the rear wheels are braked based on this steering control mode so that the braking force of the rear wheels reaches the maximum design value to maintain the rear wheels from turning. Alternatively, it can be understood that braking the rear wheels after receiving a driver's request to enter the steering control mode indicates that the vehicle has entered the steering control mode.

[0094] In this embodiment, tire adhesion refers to the limit value of the tangential reaction force of the tire on the ground (contact surface), and braking force refers to the friction force between the brake pads and the brake disc. The brake disc is rigidly connected to the tire. By controlling the friction force between the brake pads and the brake disc, the tire is kept stationary. Finally, effective braking force is provided by the ground friction force. The maximum effective braking force of the brake tire is the tire adhesion.

[0095] As an example, the aforementioned braking of the rear wheels specifically includes braking the left and right rear wheels respectively, wherein the braking force of the left rear wheel is greater than or equal to the tire adhesion force corresponding to the left rear wheel, and the braking force of the right rear wheel is greater than or equal to the tire adhesion force corresponding to the right rear wheel. For example, assuming the tire adhesion forces of the left and right rear wheels are equal, the braking force of a single rear wheel satisfies the following formula 1, where F... b For braking force on a single rear wheel, S b For tire adhesion of a single rear wheel, This is the formula for calculating the tire adhesion of a single rear wheel. Where M is the vehicle's curb weight, m ​​is the mass of the load carried by the vehicle, g is the acceleration due to gravity, μ is the ground adhesion coefficient (generally taken as greater than or equal to 0.95 and less than or equal to 1.2), a is the distance from the vehicle's center of gravity to the center of the front axle, and b is the distance from the vehicle's center of gravity to the center of the rear axle.

[0096]

[0097] In one possible implementation, m can be a preset mass (the preset mass of the objects carried by the vehicle), for example, the preset mass could be the preset mass of a single person, or it could be the preset mass of a full load. Based on this preset mass, S can be determined. b The maximum value, and then based on this S b The maximum value of F is determined b The minimum value, and based on this F b The minimum value of the correlation coefficient of the braking control device corresponding to the vehicle is used to design the vehicle.

[0098] S204 determines the steering angle of the front wheels based on the driver's input to the steering wheel.

[0099] Specifically, the front wheels are connected to a steering mechanism, which includes a steering wheel, a steering column, and a steering tie rod. The steering mechanism can obtain the steering wheel rotation angle through a steering wheel angle sensor (angle sensor) and then calculate the tire angle.

[0100] S205, based on the user's operation information regarding the throttle and gear, the first motor outputs the corresponding torque to drive the front wheels.

[0101] Specifically, the throttle depth is obtained based on the user's throttle input information; the output torque of the first motor (the motor corresponding to the front wheels) is determined based on the throttle depth; and the direction of the first motor's output torque is obtained based on the driver's gear selection information, where the gears include forward and reverse gears. In this embodiment, the first motor drives the front axle to drive the left and right front wheels.

[0102] S206, when the front axle driving force output by the first motor corresponding to the front wheel is less than or equal to the tire adhesion of the front wheel, or the steering angle of the front wheel is less than or equal to the first steering angle, the vehicle remains stationary.

[0103] Understandably, since the materials, number of tires, and coefficient of friction of the front and rear tires are generally the same, the tire adhesion of the first set of tires is usually not much different from that of the second set. In other words, before the front axle driving force increases to a level greater than the tire adhesion of the front tires, this front axle driving force is generally also less than the tire adhesion of the rear tires when they are not rotating (the maximum effective braking force in the longitudinal direction of the vehicle). Therefore, before the front axle driving force increases to a level greater than the tire adhesion of the front tires, the distance the vehicle moves is almost zero or very small.

[0104] In some possible implementations, to further reduce the distance the vehicle travels after the front axle driving force increases to be greater than the tire adhesion of the rear wheels and before it increases to be greater than the tire adhesion of the front wheels, the ground adhesion coefficient of the rear wheels is greater than the ground adhesion coefficient of the front wheels, and / or, a first distance 'a' between the vehicle's center of gravity and the center of the front axle is greater than a second distance 'b' between the vehicle's center of gravity and the center of the rear axle. For example, b is greater than or equal to 0.95a and less than or equal to 0.999a.

[0105] S207, when the front axle driving force is greater than the tire adhesion of the front wheels and the steering angle of the front wheels is greater than the first steering angle, the vehicle turns.

[0106] When the front axle driving force output by the first motor corresponding to the front wheels is greater than the tire adhesion of the front wheels, the front wheels are in a slipping state. The longitudinal traction force generated by this front axle driving force on the front wheels is less than the longitudinal braking force generated by the rear wheels, and the vehicle cannot move longitudinally based on the traction force of the front wheels. However, when the front axle driving force is greater than the tire adhesion of the front wheels and the steering angle of the front axle is greater than the first steering angle, the front axle generates a front axle lateral force that produces a yaw moment on the vehicle. The rear wheels are not rotating, and the rear axle almost loses its ability to generate a rear axle lateral force. The rear wheels cannot stop the vehicle from yawing, so the vehicle yaws with a small turning radius based on this front axle lateral force. Specifically, it can be understood as the vehicle performing a yaw motion that is almost like rotating on the spot.

[0107] The value of the turning radius corresponding to the vehicle's steering is related to the size of the first steering angle and the distance between the center of the first set of tires and the center of the second set of tires.

[0108] As an example, the front axle driving force D and the front wheel tire adhesion force S a It satisfies the following formula 2. Where, T max denoted as peak torque of the front motor, i as gear ratio of the reducer, r as tire radius, M as vehicle curb weight, and m as mass of the load carried by the vehicle.

[0109]

[0110] Specifically, based on Formula 2, the peak torque of the first motor is greater than a first value, which is determined based on the tire adhesion of the front wheel, the speed ratio of the reducer, and the tire radius. The specific calculation formula for this first value can be derived from Formula 2.

[0111] As an example, m in Formula 2 can be a preset mass (the preset mass of the objects carried by the vehicle), such as a preset single-person mass or a preset full-load mass. Based on this preset mass, S can be determined. a The maximum value, and then based on this S a The maximum value of D determines the minimum value of D, and the minimum value of D determines the lower limit of the peak torque of the first motor.

[0112] In this embodiment of the application, the direction of vehicle steering can be left front, right front, right rear, or left rear, depending on the vehicle's throttle gear and the steering angle of the front axle.

[0113] As an example, a vehicle's gears include a forward gear (D) and a reverse gear (R). The driver determines the vehicle's direction of steering by using the gear selection and steering wheel angle. Specifically, in D gear, turning the steering wheel to the left turns the vehicle forward to the left, and turning it to the right turns the vehicle forward to the right. In R gear, turning the steering wheel to the left turns the vehicle backward to the right, and turning it to the right turns the vehicle backward to the left.

[0114] S208, determine whether the second preset condition for exiting the steering control mode is met.

[0115] As an example, the second preset condition includes, but is not limited to, one or more of the following: receiving a user request message to exit the steering control mode, vehicle overheating, insufficient vehicle power, or other equipment malfunction. When the vehicle meets any one of the second preset conditions, it is determined that the vehicle meets the second preset condition for exiting the steering control mode.

[0116] If the second preset condition is met, steps S209 and S210 are executed sequentially. If the second preset condition is not met, steps S204-S208 are executed.

[0117] S209, unload the output torque of the first motor.

[0118] Specifically, the torque of the first motor is reduced to 0.

[0119] S210, unloading the braking force of the rear wheels.

[0120] Specifically, the braking force on the rear wheels is reduced to 0.

[0121] In conjunction with the vehicle steering method described above, this application also provides a vehicle steering system, the system including a steering control unit, a first set of tires, a second set of tires, a braking force control unit, a motor controller, a motor, and a steering mechanism, wherein the first set of tires are the front wheels and the second set of tires are the rear wheels, or the first set of tires are the rear wheels and the second set of tires are the front wheels; the steering control unit is used to request the braking force control unit to brake the second set of tires, so that the second set of tires is in a non-rotating state; the steering mechanism is used to change the steering angle of the first set of tires; the steering control unit is used to request the motor controller to control the output torque of the motor so that the motor drives the first set of tires; the steering control unit is also used to control the vehicle to steer when the steering angle of the first set of tires is greater than a first steering angle and the driving force output by the motor is greater than the tire adhesion of the first set of tires.

[0122] In some possible implementations, the system further includes a steering control mode request input device and an in-vehicle network. The steering control mode request input device is used to receive user request information to enter the steering control mode. The steering control unit is specifically used to respond to the user's input request to enter the steering control mode, determine to enter the steering control mode, and request the braking force control unit to brake the second set of tires based on the steering control mode, so that the second set of tires is in a non-rotating state. The steering control unit is also used to obtain throttle depth and gear status based on the in-vehicle network, and determine the magnitude of the motor torque output by the motor controller based on the throttle depth, and determine the direction of the motor torque output by the motor controller based on the gear status. The steering control unit is also used to request the motor controller to control the motor to output torque corresponding to the magnitude and direction of the motor torque. The steering mechanism is specifically used to determine the steering angle of the first set of tires based on the steering wheel rotation angle obtained by the angle sensor. The motor controller is specifically used to control the motor to output torque corresponding to the motor torque direction and magnitude requested by the steering control unit, so as to drive the first set of tires.

[0123] For example, taking a first set of tires including a left front wheel and a right front wheel, a second set of tires including a left rear wheel and a right rear wheel, and the motor corresponding to the first set of tires being driven by a single motor, the vehicle steering system provided in this application is described in conjunction with Figure 3.

[0124] As shown in Figure 3, the vehicle steering system provided in this application includes: a steering control mode request input device 301, a steering control unit 302, front wheels 303, rear wheels 304, a braking force control unit 305, an in-vehicle network 306, a motor controller 307, a first motor 308, a final drive 309, a steering mechanism 310, a front axle 311, and a rear axle 312. The front axle 311 connects the left and right front wheels of the front wheels 303, and the rear axle 312 connects the left and right rear wheels of the rear wheels 304. The steering mechanism 310 is connected to the front wheels 303.

[0125] The steering control mode request input device 301 is used to receive operation information from the user requesting to enter the steering control mode.

[0126] The steering control unit 302 is used to respond to the user's request to enter the steering control mode, determine to enter the steering control mode, and request the braking force control unit 305 to brake the rear wheel 304 based on the steering control mode, so that the rear wheel 304 is in a non-rotating state. Specifically, it can brake the left rear wheel and the right rear wheel separately, wherein the braking force of the left rear wheel and the right rear wheel is greater than or equal to the adhesion force corresponding to one of the rear tires (refer to Formula 1 above).

[0127] The steering mechanism 310 is used to determine the steering angle of the front wheels based on the rotation angle of the steering wheel obtained by the angle sensor.

[0128] The steering control unit 302 is also used to obtain throttle depth and gear status based on the vehicle network 306, and determine the magnitude of the motor torque output by the motor controller 307 controlling the first motor 308 based on the throttle depth, and determine the direction of the motor torque output by the first motor controller 308 controlling the motor based on the gear status.

[0129] The steering control unit 302 is further configured to request the motor controller to control the motor to output a torque corresponding to the magnitude and direction of the motor torque, so as to drive the front axle 311 to drive the front wheels; the steering control unit 302 is further configured to control the vehicle to steer when the steering angle of the front wheels is greater than a first steering angle and the driving force corresponding to the torque output by the first motor 308 is greater than the tire adhesion of the front wheels. The tire adhesion of the front wheels (also referred to as the front axle adhesion) is the sum of the adhesion corresponding to the left front wheel and the adhesion corresponding to the right front wheel.

[0130] In some possible implementations, the peak torque of the first motor 308 is greater than a first value, which is determined based on the tire grip of the front wheel 303, the speed ratio of the final drive 309, and the tire radius of the front wheel 303. The specific calculation method for the first value can be found in the relevant description above, for example, in the description of Formula 2 above.

[0131] In some possible implementations, the tire adhesion of the front wheels is determined based on the vehicle mass, a preset single-person mass, the coefficient of friction of the contact surface, gravitational acceleration, a first distance between the vehicle's center of mass and the center of the front axle 311, and a second distance between the vehicle's center of mass and the center of the rear axle 312.

[0132] In some possible implementations, the first distance between the vehicle's center of gravity and the center of the front axle is greater than the second distance between the vehicle's center of gravity and the center of the rear axle.

[0133] In some possible implementations, the steering control unit 302 is also used to output a first indication message and control the vehicle to exit the steering control mode when the driving force output after the motor of the first set of tires reaches the peak motor torque is still less than or equal to the tire adhesion of the front wheels and the vehicle is stationary. The first indication message is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for steering the vehicle using the steering control mode.

[0134] It should be noted that in the vehicle steering system shown in Figure 3, the steering angle of the rear wheels is 0. However, in practical applications, the steering angle of the rear wheels may not be 0. Furthermore, the different steering angles of the rear wheels do not have different effects on the braking effect achieved by the vehicle or on the turning radius corresponding to the vehicle steering method. This article does not impose any restrictions on this.

[0135] In some possible implementations, the aforementioned steering control unit 302 is further configured to obtain the maximum mass that the first motor 308 can drive, which is related to the maximum driving force corresponding to the peak torque of the first motor 308; the steering control unit 302 is further configured to obtain the total mass of the vehicle, which includes the vehicle's curb weight and the mass of the actual load carried by the vehicle, specifically by adding a height sensor to the vehicle's suspension and combining it with the known suspension stiffness to obtain the mass of the actual load carried by the vehicle; the steering control unit 302 is specifically configured to, in response to user input of operation information indicating that the vehicle should enter the steering control mode, control the vehicle to enter the steering control mode when the maximum mass is greater than the total mass.

[0136] In some possible implementations, the aforementioned steering control unit 302 is further configured to, when the maximum mass is less than the vehicle's curb weight, control the vehicle to output second indication information in response to user-inputted operation information indicating that the vehicle's performance does not support entering the steering control mode; and when the maximum mass is greater than the vehicle's curb weight but less than the total mass, control the vehicle to output third indication information in response to user-inputted operation information indicating that the mass of the object carried by the vehicle exceeds the maximum mass for entering the steering control mode.

[0137] It should be noted that the specific execution process can be found in the detailed description of the embodiments shown in Figure 1 or Figure 2, and will not be repeated here.

[0138] It is understandable that the vehicle steering system provided in Figure 3 is used to execute the vehicle steering method shown in Figure 1 or Figure 2. Therefore, the beneficial effects it can achieve can be referred to the beneficial effects in the corresponding methods, which will not be repeated here.

[0139] In conjunction with the vehicle steering method described above, this application also provides a vehicle steering device. Referring to FIG4, the device is applied to a vehicle, the vehicle including a first set of tires and a second set of tires, wherein the first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel. The device includes:

[0140] Braking unit 401 is used to brake the second set of tires, so that the second set of tires is in a non-rotating state;

[0141] Steering unit 402 is used to control the steering angle of the first set of tires;

[0142] Drive unit 403 is used to drive the first set of tires;

[0143] The first control unit 404 is used to control the vehicle steering based on the driving force and the steering angle of the first set of tires when the driving force driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than the first steering angle.

[0144] In some possible implementations, the peak torque of the motor corresponding to the first set of tires is greater than a first value, which is determined based on the tire adhesion of the first set of tires, the reducer speed ratio, and the tire radius of the first set of tires.

[0145] In some possible implementations, the ground adhesion coefficient corresponding to the second set of tires is greater than that corresponding to the first set of tires, and / or, the first distance between the center of gravity of the vehicle and the center of the first set of tires is greater than the second distance between the center of gravity of the vehicle and the center of the second set of tires.

[0146] In some possible implementations, as shown in Figure 5, the device further includes: a second control unit 405, configured to control the vehicle to enter the steering control mode in response to information indicating that the vehicle has entered the steering control mode. Specifically, the second control unit 405 includes: a receiving subunit 4051, configured to receive user-inputted operation information instructing the vehicle to enter the steering control mode; and a control subunit 4052, configured to control the vehicle to enter the steering control mode in response to user-inputted operation information instructing the vehicle to enter the steering control mode.

[0147] In some possible implementations, the vehicle further includes an accelerator and gears, and the device further includes: a first acquisition unit 406, used to acquire gear information of the vehicle, the gear information including forward gears and reverse gears; specifically, the first acquisition unit 406 can be used to acquire the gear information of the vehicle based on user operation information regarding the gears; a second acquisition unit 407, used to acquire throttle depth information. Specifically, the second acquisition unit 407 can be used to acquire throttle depth information based on user operation information regarding the throttle. The drive unit 403 is specifically used to control the vehicle's motor to output corresponding torque magnitude and torque direction based on the throttle depth information and the gear information, so as to drive the first set of tires.

[0148] In some possible implementations, the steering unit 402 is specifically used to determine the steering angle of the first set of tires based on the steering wheel rotation angle obtained by the angle sensor.

[0149] In some possible implementations, the above-mentioned device further includes: an output unit 408, which is used to output first indication information and control the vehicle to exit steering control when the driving force output by the motor driving the first set of tires after the motor reaches the peak torque of the drive unit is still less than or equal to the tire adhesion of the first set of tires and the vehicle is stationary. The first indication information is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for vehicle steering using the vehicle steering method.

[0150] In some possible implementations, the above-mentioned device further includes: a third acquisition unit 409, used to acquire the maximum mass that the motor corresponding to the first set of tires can drive, the maximum mass being related to the maximum driving force corresponding to the peak torque of the motor; a fourth acquisition unit 410, used to acquire the total mass of the vehicle, the total mass including the vehicle's curb weight and the mass of the objects actually carried by the vehicle; and the second control unit 405, specifically used to, in response to user input of operation information indicating that the vehicle should enter the steering control mode, when the maximum mass is greater than the total mass, allow the vehicle to enter the steering control mode.

[0151] In some possible implementations, the output unit 408 is further configured to, when the maximum mass is less than the vehicle's curb weight, output second indication information in response to user-inputted operation information indicating that the vehicle's performance does not support entering the steering control mode; and when the maximum mass is greater than the vehicle's curb weight but less than the total mass, output third indication information in response to user-inputted operation information indicating that the vehicle's performance does not support entering the steering control mode; and when the maximum mass is greater than the vehicle's curb weight but less than the total mass, output third indication information in response to user-inputted operation information indicating that the mass of the object carried by the vehicle exceeds the maximum mass for the vehicle to enter the steering control mode.

[0152] In some possible implementations, the first set of tires includes a left front wheel and a right front wheel, the second set of tires includes a left rear wheel and a right rear wheel, the vehicle also includes a first motor and a front axle, the front axle is used to connect the left front wheel and the right front wheel, the first motor is used to drive the left front wheel and the right front wheel through the front axle, the first adhesion force is the sum of the adhesion force corresponding to the left front wheel and the adhesion force corresponding to the right front wheel; the braking unit 401 is specifically used to individually control the braking state of the left rear wheel and the right rear wheel; the braking unit 401 is specifically used to brake the left rear wheel and the right rear wheel respectively with a first braking force, the first braking force is greater than the first adhesion force, and the first adhesion force is the adhesion force corresponding to one of the tires in the second set of tires.

[0153] As an example, the braking force control unit 305 in the vehicle steering system of Figure 3 can be used to implement the steps or functions performed by the braking unit 401 in Figure 4; the motor controller 307 and the first motor 308 can be used to implement the steps or functions performed by the drive unit 403; the steering mechanism can be used to implement the steps and functions performed by the steering unit 402; the steering control unit 302 can be used to implement the steps or functions performed by the second control unit 405 and the first control unit 404; and the vehicle network 306 can be used to implement the steps or functions performed by the first acquisition unit 406 and the second acquisition unit 407.

[0154] As an example, the braking unit 401 described above can be a braking force control unit in an electro-hydraulic braking system, the structure of which can be as shown in Figure 6.

[0155] In the electro-hydraulic braking system, the brake force control unit controls the hydraulic cylinder pressure of the rear wheel brake force control device via a solenoid valve, thereby controlling the braking force applied to the brake disc. Specifically, to apply maximum braking force to the rear wheels individually, the brake force control unit first closes all pressure boosting and pressure relief valves. After the cylinder pressure of the master cylinder reaches its maximum value through the wheel cylinder motor, the front wheel pressure boosting valve remains closed, while the rear wheel pressure boosting valve is opened. Once the rear wheel brake cylinder pressure stabilizes, the pressure boosting valve is closed, maintaining the rear wheel cylinder pressure at the maximum braking pressure. Then, the wheel cylinder motor is controlled to restore the master cylinder pressure to its normal value. Specifically, to unload braking force from the rear wheels individually, the rear wheel pressure boosting valve remains closed, the rear wheel pressure relief valve is opened, and after a certain period, the rear wheel cylinder pressure drops to 0. The pressure relief valve is then closed, and the rear wheel braking force is unloaded to 0.

[0156] As another example, the aforementioned braking unit 401 can also be a braking force control unit in an electronic parking brake system.

[0157] In the electronic parking brake system, the brake force control unit mechanically limits the hydraulic cylinder pressure of the rear wheel braking force control device via the rear wheel parking motor, thereby controlling the braking force applied to the brake disc to reach the maximum design value. The electronic parking brake system itself can control the rear wheel braking force to maintain at its maximum value. Generally, the electronic parking brake system will actively unload the rear wheel braking force after monitoring that the vehicle's driving torque reaches a certain threshold, in order to satisfy the driver's intention to switch from parking to driving. In this embodiment, after receiving the braking request for the rear wheels from the steering control unit, the electronic parking brake system outputs driving force, but the electronic parking brake system will not apply rear wheel braking force based on the driving force exceeding a certain threshold. The electronic parking brake system will keep the rear wheels in a braking state and will not actively unload the rear wheel braking force. Instead, it will unload the rear wheel braking force only after determining that the second preset condition for exiting the steering control mode is met and the driving force is unloaded.

[0158] It should be noted that the specific execution process can be found in the detailed description of the embodiments shown in Figure 1 or Figure 2, and will not be repeated here.

[0159] It is understandable that the vehicle steering device provided in Figure 4 is a device for performing the vehicle steering method shown in Figure 1 or Figure 2. Therefore, the beneficial effects it can achieve can be referred to the beneficial effects in the corresponding methods, and will not be repeated here.

[0160] This application also provides a vehicle comprising a controller, a motor controller, a brake controller, a first set of tires, and a second set of tires. The first set of tires is the front wheel, and the second set of tires is the rear wheel, or the first set of tires is the rear wheel, and the second set of tires is the front wheel. The controller is configured to request the brake force controller to brake the second set of tires and to request the motor control unit to drive the first set of tires to execute any possible vehicle steering method shown in Figure 1 or Figure 2, thereby achieving vehicle steering. As an example, Figure 7 illustrates a schematic diagram of the vehicle provided in this application, with the first set of tires including the left and right front wheels, and the second set of tires including the left and right rear wheels.

[0161] For example, the controller can be used to implement the steps or functions performed by the steering control unit mentioned above. In some possible implementations, the motor controller can be used to implement the steps or functions performed by the motor controller mentioned above (e.g., in Figure 3), the brake controller can be used to implement the steps or functions performed by the braking force control unit mentioned above, and the controller can also be used to implement the steps or functions performed by the steering control mode request input device mentioned above.

[0162] As used in the above embodiments, depending on the context, the term "when..." can be interpreted as meaning "if...", "after...", "in response to determining...", or "in response to detecting...". Similarly, depending on the context, the phrase "when determining..." or "if (the stated condition or event) is interpreted as meaning "if determining...", "in response to determining...", "when (the stated condition or event) is detected", or "in response to detecting (the stated condition or event)".

[0163] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. This computer program product includes one or more computer instructions. When these computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible to a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive), etc.

[0164] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. This program can be stored in a computer-readable storage medium, and when executed, it can include the processes described in the above method embodiments. The aforementioned storage medium includes various media capable of storing program code, such as ROM or random access memory (RAM), magnetic disks, or optical disks.

Claims

1. A vehicle steering method, characterized in that, include: The second set of tires is braked so that it is in a non-rotating state. The braking force of the second set of tires is greater than or equal to the second adhesion force, which is related to the total mass of the vehicle, gravitational acceleration, ground adhesion coefficient, second distance between the center of the second set of tires and the center of gravity of the vehicle, and first distance between the center of the first set of tires and the center of gravity of the vehicle. The first set of tires is driven, and the driving force torque of each tire in the first set of tires is in the same direction. The peak torque of the motor driving the first set of tires is greater than a first value, which is determined based on the reducer ratio, the tire adhesion of the first set of tires, and the tire radius. When the driving force driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than a first steering angle, the vehicle steering is controlled based on the driving force and the steering angle of the first set of tires. The steering angle of the first set of tires is the angle between the first set of tires and the vehicle body. The first set of tires are the front wheels of the vehicle, and the second set of tires are the rear wheels of the vehicle, or the first set of tires are the rear wheels of the vehicle, and the second set of tires are the front wheels of the vehicle. The second distance is greater than or equal to a first preset multiple of the first distance, and the first preset multiple is a value less than 1 and greater than or equal to 0.

95.

2. The method according to claim 1, characterized in that, Before braking the second set of tires, the method further includes: controlling the vehicle to enter a steering control mode in response to information that the vehicle has entered a steering control mode; braking the second set of tires includes: braking the second set of tires based on the steering control mode.

3. The method according to claim 1 or 2, characterized in that, Before driving the first set of tires, the method further includes: acquiring the vehicle's gear information, the gear information including forward gear and reverse gear; acquiring throttle depth information; driving the first set of tires includes: controlling the vehicle's motor to output corresponding torque magnitude and torque direction based on the throttle depth information and the gear information, so as to drive the first set of tires.

4. The method according to claim 1 or 2, characterized in that, The method further includes: when the driving force output by the motor used to drive the first set of tires is still less than or equal to the tire adhesion of the first set of tires after the motor reaches the peak torque, and the vehicle is stationary, outputting first indication information and controlling the vehicle to exit steering control, wherein the first indication information is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for vehicle steering using the vehicle steering method.

5. The method according to claim 1 or 2, characterized in that, The braking of the second group of tires includes: applying braking force to brake the left rear wheel and the right rear wheel respectively, wherein the braking force is greater than or equal to the tire adhesion force corresponding to one of the tires in the second group of tires, and the second group of tires includes the left rear wheel and the right rear wheel.

6. A vehicle steering device, characterized in that, include: A braking unit is used to brake the second set of tires so that the second set of tires is in a non-rotating state. The braking force of the second set of tires is greater than or equal to the second adhesion force. The second adhesion force is related to the total mass of the vehicle, gravitational acceleration, ground adhesion coefficient, a second distance between the center of the second set of tires and the center of gravity of the vehicle, and a first distance between the center of the first set of tires and the center of gravity of the vehicle. A drive unit is used to drive the first set of tires. The peak torque of the motor corresponding to the first set of tires is greater than a first value, which is determined based on the reducer ratio, the tire adhesion of the first set of tires, and the tire radius. A first control unit is used to control the vehicle steering based on the drive force and the steering angle of the first set of tires when the driving force of the drive unit driving the first set of tires is greater than the tire adhesion of the first set of tires and the steering angle of the first set of tires is greater than a first steering angle. The steering angle of the first set of tires is the angle between the first set of tires and the vehicle body. The first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel. The second distance is greater than or equal to a first preset multiple of the first distance, and the first preset multiple is a value less than 1 and greater than or equal to 0.

95.

7. The apparatus according to claim 6, characterized in that, The device further includes: a second control unit, configured to control the vehicle to enter a steering control mode in response to information indicating that the vehicle has entered a steering control mode; and a braking unit, specifically configured to brake the second set of tires based on the steering control mode.

8. The apparatus according to claim 6 or 7, characterized in that, The device further includes: a first acquisition unit for acquiring gear information of the vehicle, the gear information including forward gear and reverse gear; a second acquisition unit for acquiring throttle depth information; and a drive unit specifically for controlling the vehicle's motor to output corresponding torque magnitude and torque direction based on the throttle depth information and the gear information, so as to drive the first set of tires.

9. The apparatus according to claim 6 or 7, characterized in that, The device further includes an output unit, configured to output first indication information and control the vehicle to exit steering control when the driving force output by the motor driving the first set of tires after the drive unit reaches the peak motor torque is still less than or equal to the tire adhesion of the first set of tires and the vehicle is stationary. The first indication information is used to indicate that the mass of the object carried by the vehicle exceeds the maximum load capacity for vehicle steering using the vehicle steering method.

10. A vehicle, characterized in that, The vehicle includes a controller, a motor controller, a brake controller, a first set of tires, and a second set of tires, wherein the first set of tires is the front wheel and the second set of tires is the rear wheel, or the first set of tires is the rear wheel and the second set of tires is the front wheel. The controller is used to request the brake controller to brake the second set of tires and to request the motor control unit to drive the first set of tires, so as to implement the steering method as described in any one of claims 1-5, thereby achieving vehicle steering.

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