A control method, controller, and electric vehicle for an electric vehicle

Abstract

This application provides a control method, controller, and electric vehicle for use in the field of electric vehicle technology. After the electric vehicle enters a parallel road surface but before leaving it, the difference in driving torque or braking torque between a left wheel and a right wheel on the same axle is increased to prevent the torque of the lower-attached wheel from exceeding its longitudinal force limit, thus preventing wheel slippage. Simultaneously, the greater torque of the higher-attached wheel ensures the electric vehicle's driving or braking capabilities. Furthermore, by actively controlling the steering angle of the two front wheels—that is, actively controlling the steering angle of the two front wheels without the driver actively turning the steering wheel—the yaw moment generated by the lateral force of the two front wheels is actively balanced by the change in yaw moment due to the torque difference. This coordinated control of the steering system and the drive or braking system prevents the electric vehicle from yawing.

Description

Technical Field

[0001] This application relates to the field of electric vehicle technology, and more particularly to a control method, controller, and electric vehicle for an electric vehicle. Background Technology

[0002] When an electric vehicle travels on a split-level road, the difference in grip provided by the left and right wheels can cause the vehicle to veer off course. During this process, the driver must constantly turn the steering wheel to correct the vehicle's trajectory, making the operation cumbersome and achieving accurate control extremely difficult. Summary of the Invention

[0003] This application provides a control method, controller, and electric vehicle for an electric vehicle. During the process of the electric vehicle traveling on a split road, the steering system is controlled in coordination with the drive system or braking system to avoid the electric vehicle from veering off course.

[0004] In a first aspect, embodiments of this application provide a control method for an electric vehicle, comprising the following steps.

[0005] Before the electric vehicle enters the split road, the steering angle of the two front wheels of the electric vehicle is controlled to change with the steering wheel angle; and after the electric vehicle enters the split road and before it leaves the split road, the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle is increased, and the steering angle of the two front wheels is actively controlled to increase or decrease.

[0006] Among them, the difference between the adhesion coefficient between the left wheel and the road surface and the adhesion coefficient between the right wheel and the road surface when the electric vehicle is driving on the split road is greater than the preset value.

[0007] In this embodiment, before the electric vehicle enters the parallel road surface, the steering angles of the two front wheels are controlled to change with the steering wheel angle, allowing the driver to precisely control the vehicle's trajectory by operating the steering wheel. After the electric vehicle enters the parallel road surface but before leaving, the difference in driving torque or braking torque between one left wheel and one right wheel on the same axle is increased to prevent the driving torque or braking torque of the lower-attached wheel from exceeding its longitudinal force limit, thus preventing wheel slippage and affecting the vehicle's driving stability. Simultaneously, the higher-attached wheel provides greater driving or braking torque to ensure the vehicle's driving or braking capabilities. Furthermore, by actively controlling the steering angles of the two front wheels—that is, actively controlling the steering angles of the two front wheels without the driver actively turning the steering wheel—the yaw moment generated by the lateral forces of the two front wheels is actively balanced by the change in yaw moment caused by the difference in driving torque or braking torque. This coordinated control of the steering system and the drive or braking system prevents the electric vehicle from yawing.

[0008] In this embodiment of the application, when the electric vehicle is traveling on a split road, the driver does not need to constantly turn the steering wheel to correct the vehicle's trajectory, which simplifies the driver's operation and improves the driving experience.

[0009] In one embodiment of the first aspect, the control method further includes: after the electric vehicle leaves the road surface, controlling the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle to decrease, and actively controlling the steering angle of the two front wheels to decrease or increase.

[0010] In this embodiment, after the electric vehicle leaves the parallel road surface, the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle is reduced, and the steering angle of the two front wheels is actively reduced or increased. This releases the control of the electric vehicle's torque and the steering angle of the two front wheels after entering the parallel road surface, preventing the electric vehicle from remaining on the parallel road surface after leaving it and causing it to yaw, thus allowing the electric vehicle to return to normal driving status.

[0011] In one embodiment of the first aspect, the control method specifically includes: after the electric vehicle enters the split road surface and before it leaves the split road surface, controlling the difference between the driving torque or braking torque of one left wheel and one right wheel to increase, and actively controlling the steering angle of the two front wheels to increase or decrease before the steering wheel angle changes.

[0012] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the steering angle of the two front wheels is actively controlled to increase or decrease before the steering wheel angle changes. That is, during the electric vehicle's travel on the parallel road surface, the steering angle changes of the two front wheels are not transmitted to the steering wheel. The driver still operates the steering wheel according to the desired driving trajectory, avoiding tension and anxiety caused by the steering wheel turning on its own, thus improving driving comfort.

[0013] In one embodiment of the first aspect, the control method specifically includes: after the electric vehicle enters the split road surface and before it leaves the split road surface, controlling the difference between the driving torque or braking torque of one left wheel and one right wheel to increase, and actively controlling the steering wheel angle to change with the change of the steering angle of the two front wheels.

[0014] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the steering wheel angle is actively controlled to change with the steering angle of the two front wheels. That is, during the electric vehicle's travel on the parallel road surface, the steering angle changes of the two front wheels are transmitted to the steering wheel, allowing the driver to feel the changes in the steering angle of the two front wheels and to be aware of the active control operations performed by the electric vehicle. This improves the trust between the driver and the electric vehicle and facilitates the driver in performing other driving operations.

[0015] In one embodiment of the first aspect, the control method specifically includes: before controlling the difference between the driving torque or braking torque of a left wheel and a right wheel to increase, controlling the difference between the driving torque or braking torque of a left wheel and a right wheel to decrease.

[0016] In this embodiment, after the electric vehicle enters the split-path surface but before leaving it, before increasing the difference in driving torque or braking torque between one left wheel and one right wheel, the difference is first reduced. This reduces the existing difference in driving torque or braking torque, lowering the initial yaw disturbance. This prevents the difference in driving torque or braking torque between the two wheels on the same axle from directly increasing, causing the grip of the two wheels, especially the low-touch wheel, to exceed the friction limit, thus preventing the electric vehicle from losing control. Simultaneously, it facilitates the redistribution of the driving torque or braking torque difference between the two wheels in the drive system, better preventing the electric vehicle from yawing.

[0017] In one embodiment of the first aspect, the control method specifically includes: before controlling the difference between the driving torque or braking torque of a left wheel and a right wheel to increase, controlling the driving torque or braking torque of a left wheel and a right wheel to decrease simultaneously.

[0018] In this embodiment, after the electric vehicle enters the split road surface and before it leaves the split road surface, before the difference between the driving torque or braking torque of one left wheel and one right wheel increases, the driving torque or braking torque of one left wheel and one right wheel is reduced simultaneously first. This releases the longitudinal force demand of the two wheels on the same axle, and avoids the grip force of the two wheels exceeding the friction limit due to the increase in the difference between the driving torque or braking torque of the two wheels on the same axle, which would cause the electric vehicle to lose control.

[0019] In one embodiment of the first aspect, the control method specifically includes: first controlling the duration for which the driving torque or braking torque of a left wheel and a right wheel decreases simultaneously to be less than the duration for which ...

[0020] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the duration for which the driving torque or braking torque of one left wheel and one right wheel decreases simultaneously is less than the duration for which the difference between the driving torque or braking torque of one left wheel and one right wheel increases. This allows for a rapid response to the electric vehicle entering the parallel road surface by reducing torque and preventing slippage of the low-tether wheel. Additionally, the difference between the driving torque or braking torque of the two wheels on the same axle is gradually increased to prevent a sudden increase in the difference, which could cause large fluctuations in the yaw moment of the electric vehicle. This avoids sudden tail-swing or yaw of the electric vehicle and improves driving comfort.

[0021] In one embodiment of the first aspect, the control method specifically includes: the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference between the driving torque or braking torque of the left wheel and the right wheel.

[0022] In this embodiment, the greater the difference in the coefficient of adhesion between a left wheel and the road surface compared to the right wheel, the more prone the electric vehicle is to yaw. In this case, by controlling the difference in driving torque or braking torque between a left wheel and a right wheel to a greater extent, the driving torque or braking torque of the lower-adhesion wheel is prevented from exceeding its longitudinal force limit, thus avoiding wheel slippage. Meanwhile, the higher-adhesion wheel provides greater driving torque or braking torque to ensure the electric vehicle's driving or braking capabilities. This allows for flexible control of the difference in driving torque or braking torque between the two coaxial wheels and the road surface based on the difference in their coefficients of adhesion. Consequently, under varying coefficients of adhesion differences, slippage of the lower-adhesion wheel can be avoided while the higher-adhesion wheel maintains the electric vehicle's driving or braking capabilities.

[0023] In one embodiment of the first aspect, the control method specifically includes: during the process of the electric vehicle traveling in a straight line on a split road, the coefficient of adhesion between a left wheel and the road surface is less than the coefficient of adhesion between a right wheel and the road surface; when the opening of the accelerator pedal is greater than a preset accelerator pedal opening, controlling the driving torque of a left wheel to be less than the driving torque of a right wheel, and actively controlling the two front wheels to turn to the right.

[0024] In this embodiment, while the electric vehicle is traveling straight on a split road, the system automatically detects the driver's intention to operate the accelerator pedal to drive the electric vehicle by detecting that the accelerator pedal opening is greater than a preset accelerator pedal opening. In this case, by controlling the driving torque of one left wheel to be less than that of one right wheel, and the driving torque of the lower-tether wheel to be less than that of the higher-tether wheel, slippage of the lower-tether wheel is avoided while the driving capability of the electric vehicle is maintained by the higher-tether wheel. Furthermore, by actively controlling the two front wheels to steer to the right, the clockwise yaw moment generated by the lateral force of the two front wheels when steer to the right can actively balance the counterclockwise yaw moment generated by the difference in driving torque, thus preventing the electric vehicle from yawing.

[0025] In this embodiment, we take a split-road surface where the coefficient of adhesion between a left wheel and the road surface is less than that between a right wheel and the road surface as an example. The case of a split-road surface where the coefficient of adhesion between a left wheel and the road surface is greater than that between a right wheel and the road surface is exactly the same, and will not be described in detail here. The following embodiments are similar.

[0026] In one embodiment of the first aspect, the control method specifically includes: during the process of the electric vehicle traveling in a straight line on a split road, the coefficient of adhesion between a left wheel and the road surface is less than the coefficient of adhesion between a right wheel and the road surface; when the opening of the brake pedal is greater than a preset brake pedal opening, controlling the braking torque of a left wheel to be less than the braking torque of a right wheel, and actively controlling the two front wheels to turn to the left.

[0027] In this embodiment, while the electric vehicle is traveling straight on a split road, the system automatically detects the driver's intention to brake by detecting that the brake pedal opening is greater than a preset brake pedal opening. In this case, by controlling the braking torque of one left wheel to be less than that of one right wheel, and the braking torque of the lower-tethered wheel to be less than that of the higher-tethered wheel, the system avoids slippage on the lower-tethered wheel while maintaining the braking capability of the electric vehicle through the higher-tethered wheel. Furthermore, by actively controlling the two front wheels to steer to the left, the counterclockwise yaw moment generated by the lateral force of the two front wheels when steer to the left actively balances the clockwise yaw moment generated by the difference in braking torque, thus preventing the electric vehicle from yawing.

[0028] In one embodiment of the first aspect, the control method specifically includes: during the process of the electric vehicle turning left on a road surface, the coefficient of adhesion between a left wheel and the road surface is less than the coefficient of adhesion between a right wheel and the road surface; when the opening of the accelerator pedal is greater than the preset accelerator pedal opening, the difference in driving torque between a left wheel and a right wheel on the same axle is increased, and the leftward turning angle of the two front wheels is actively reduced.

[0029] In this embodiment, during the left turn of the electric vehicle on a road surface, by controlling the driving torque of one left wheel to be less than that of one right wheel, and the driving torque of the lower-tethered wheel to be less than that of the higher-tethered wheel, slippage of the lower-tethered wheel is avoided while the driving capability of the electric vehicle is maintained by the higher-tethered wheel. Furthermore, by actively controlling the leftward turning angle of the two front wheels to decrease, and considering the counterclockwise yaw moment generated by the difference in driving torque between the two wheels on the same axle, the counterclockwise yaw moment generated by the lateral force of the two front wheels is reduced, keeping the total yaw moment of the electric vehicle constant and preventing yaw.

[0030] In one embodiment of the first aspect, the control method specifically includes: during the process of an electric vehicle turning left on a road surface, the coefficient of adhesion between a left wheel and the road surface is less than the coefficient of adhesion between a right wheel and the road surface; when the opening of the brake pedal is greater than a preset brake pedal opening, the difference in braking torque between a left wheel and a right wheel on the same axle is increased, and the leftward turning angle of the two front wheels is actively increased.

[0031] In this embodiment, during the left turn of the electric vehicle on a road surface, by controlling the braking torque of one left wheel to be less than that of one right wheel, and the braking torque of the lower-tether wheel to be less than that of the higher-tether wheel, slippage of the lower-tether wheel is avoided while the braking capacity of the electric vehicle is maintained by the higher-tether wheel. Furthermore, by actively controlling the leftward turning angle of the two front wheels to increase, while considering the clockwise yaw moment generated by the difference in braking torque between the two wheels on the same axle, the counterclockwise yaw moment generated by the lateral force of the two front wheels is increased. This actively balances the clockwise yaw moment caused by the difference in braking torque, keeping the total yaw moment of the electric vehicle constant and preventing yaw.

[0032] In one embodiment of the first aspect, the control method further includes: actively controlling the steering of the two rear wheels while the electric vehicle is traveling on a split road, wherein the steering direction of the two rear wheels is different from the steering direction of the two front wheels.

[0033] In this embodiment, during the electric vehicle's travel on a split road, the steering of the two rear wheels is actively controlled, and the steering directions of the two rear wheels are different from those of the two front wheels. This results in the yaw moment generated by the lateral force of the wheels being a superposition of the yaw moment generated by the lateral force of the two rear wheels on top of the yaw moment generated by the lateral force of the two front wheels. This achieves a synergistic balance between the two, resulting in a yaw moment caused by the difference between the driving torque or braking torque, thereby preventing the electric vehicle from yawing.

[0034] In one embodiment of the first aspect, the control method specifically includes: the greater the opening of the accelerator pedal, the greater the change in the steering angle of the two front wheels actively controlled.

[0035] In this embodiment, a larger accelerator pedal opening indicates a stronger driving capability required from the electric vehicle. This also leads to a greater difference in the driving torque between the two coaxial wheels, resulting in a larger yaw moment and making the electric vehicle more prone to yaw. In this situation, by actively controlling the larger change in the steering angle of the two front wheels, the changing yaw moment caused by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in driving torque. This allows for flexible and active control of the change in the steering angle of the two front wheels based on the accelerator pedal opening, thereby preventing the electric vehicle from yawing under different accelerator pedal opening conditions.

[0036] In one embodiment of the first aspect, the control method specifically includes: the greater the opening of the brake pedal, the greater the change in the steering angle of the two front wheels is actively controlled.

[0037] In this embodiment, a larger brake pedal opening indicates a stronger braking capability required from the electric vehicle. This also leads to a greater difference in braking torque between the two wheels on the same axle, resulting in a larger yaw moment and making the electric vehicle more prone to yaw. In this situation, by actively controlling the larger change in the steering angle of the two front wheels, the changing yaw moment caused by the change in lateral force of the two front wheels can balance the increased yaw moment caused by the difference in braking torque. This allows for flexible and active control of the change in the steering angle of the two front wheels based on the brake pedal opening, thereby preventing the electric vehicle from yawing under different accelerator pedal openings.

[0038] In one embodiment of the first aspect, the control method specifically includes: the greater the rate of increase or decrease of the difference between the driving torque or braking torque of a left wheel and a right wheel, the greater the rate of change of the steering angle of the two front wheels actively controlled.

[0039] In this embodiment, before the electric vehicle enters the split road surface, the greater the rate of increase or decrease of the difference between the driving torque or braking torque of one left wheel and one right wheel, the greater the rate of change of the steering angle of the two front wheels, so that the change of the steering angle of the two front wheels and the change of the difference between the driving torque or braking torque of one left wheel and one right wheel are synchronized. That is, the changing yaw moment generated by the change of the lateral force of the two front wheels can balance the yaw moment generated by the difference between the braking torque or driving torque, thereby preventing the electric vehicle from yawing.

[0040] In one embodiment of the first aspect, the control method specifically includes: the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the change in the steering angle of the two front wheels is actively controlled.

[0041] In this embodiment, the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference in driving torque or braking torque between the two wheels on the same axle, and the greater the yaw moment generated by this difference. In this case, by actively controlling the change in the steering angle of the two front wheels, the changing yaw moment generated by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in braking torque. This allows for flexible control of the change in the steering angle of the two front wheels based on the difference in the coefficient of adhesion between the two wheels on the same axle and the road surface, thereby preventing the electric vehicle from yawing under different differences in coefficient of adhesion.

[0042] Secondly, embodiments of this application provide a controller, which is used to: control the steering angle of the two front wheels of the electric vehicle to change with the steering wheel angle before the electric vehicle enters the split road surface; control the difference between the driving torque or braking torque of a left wheel and a right wheel on the same axle to increase after the electric vehicle enters the split road surface and before leaving the split road surface, and actively control the steering angle of the two front wheels to increase or decrease; wherein, during the electric vehicle's travel on the split road surface, the difference between the adhesion coefficient between a left wheel and the road surface and the adhesion coefficient between a right wheel and the road surface is greater than a preset value.

[0043] In one embodiment, the controller may be a central controller.

[0044] In another embodiment, the controller can be a controller used for controlling the electric vehicle's operation on split-level roads. The two can serve as backups for each other, improving the control stability of the electric vehicle.

[0045] Thirdly, embodiments of this application provide an electric vehicle, which includes a controller and four wheels, wherein: The controller is used to: control the steering angle of the two front wheels of the electric vehicle to change with the steering wheel angle before the electric vehicle enters the split road surface; after the electric vehicle enters the split road surface and before it leaves the split road surface, control the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle to increase, and actively control the steering angle of the two front wheels to increase or decrease; wherein, during the electric vehicle's travel on the split road surface, the difference between the adhesion coefficient between one left wheel and the road surface and the adhesion coefficient between one right wheel and the road surface is greater than a preset value.

[0046] The supplementary solutions and technical effects provided in the second and third aspects above can be found in the corresponding descriptions in the first aspect, and will not be repeated here. Attached Figure Description

[0047] Figure 1 A schematic diagram of a control method for an electric vehicle is shown; Figure 2A schematic diagram of an electric vehicle provided in an embodiment of this application is shown; Figure 3 A schematic diagram of an electric vehicle architecture provided in an embodiment of this application is shown; Figure 4 A schematic diagram of another electric vehicle architecture provided in an embodiment of this application is shown; Figure 5 A schematic diagram of a driving scenario for an electric vehicle provided in an embodiment of this application is shown; Figure 6 This paper illustrates a timing diagram relating the accelerator pedal opening, drive torque, and steering angle of the two front wheels, according to an embodiment of this application. Figure 7 This paper presents a timing diagram showing the opening degree of a brake pedal, braking torque, and the steering angle of the two front wheels according to an embodiment of this application. Figure 8 This illustration shows a timing diagram between the difference in drive torque, the steering angle of the two front wheels, and the steering wheel angle, according to an embodiment of this application. Figure 9 This illustration shows a timing diagram between the difference in drive torque, the steering angle of the two front wheels, and the steering wheel angle, according to another embodiment of this application. Figure 10 A flowchart of a control method for an electric vehicle provided in an embodiment of this application is shown; Figure 11 A schematic diagram of a controller provided in an embodiment of this application is shown; Figure 12 A schematic diagram of the operating logic of a controller provided in an embodiment of this application is shown. Detailed Implementation

[0048] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0049] The use of prefixes such as "first" and "second" in this application embodiment is solely for distinguishing different descriptive objects and does not limit the position, order, priority, quantity, or content of the described objects. The use of ordinal numbers and other prefixes to distinguish descriptive objects in this application embodiment does not constitute a limitation on the described objects. The description of the described objects is found in the claims or the context of the embodiments, and the use of such prefixes should not constitute unnecessary restrictions.

[0050] When an electric vehicle travels on a split-level road, the significant difference in grip provided by the left and right wheels can cause it to yaw. In one embodiment, the controller only corrects the yaw by adjusting the steering wheel angle based on the detected path and heading deviations after the vehicle has yawed. (See [link to relevant documentation]). Figure 1 , Figure 1 A schematic diagram of a control method for an electric vehicle is shown, which cannot prevent the electric vehicle from yawing in advance.

[0051] In view of this, embodiments of this application provide a control method, controller, and electric vehicle for an electric vehicle. Before the electric vehicle enters a road surface, the steering angles of the two front wheels are controlled to change with the steering wheel angle, allowing the driver to precisely control the vehicle's trajectory by operating the steering wheel. After the electric vehicle enters the road surface but before leaving it, the difference in driving torque or braking torque between a left wheel and a right wheel on the same axle is increased to prevent the driving torque or braking torque of the lower-attached wheel from exceeding its longitudinal force limit, thus preventing wheel slippage and affecting the vehicle's driving stability. Simultaneously, the higher-attached wheel provides greater driving or braking torque to ensure the vehicle's driving or braking capabilities. Furthermore, by actively controlling the increase or decrease of the steering angles of the two front wheels—that is, actively controlling the increase or decrease of the steering angles of the two front wheels without the driver actively turning the steering wheel—the yaw moment generated by the lateral force of the two front wheels is actively balanced by the change in yaw moment generated by the difference in driving torque or braking torque. This coordinated control of the steering system and the drive or braking system prevents the electric vehicle from yawing.

[0052] See Figure 2 , Figure 2 A schematic diagram of an electric vehicle provided in an embodiment of this application is shown. (As shown) Figure 2 As shown, the electric vehicle 100 includes a drive system 110, a braking system 120, a power battery 130, a vehicle controller 140, and a steering system 150. The drive system 110 drives the electric vehicle 100. The power battery 130 provides electrical energy to the drive system 110, braking system 120, and steering system 150. The vehicle controller 140 controls the drive system 110 and steering system 150. The steering system 150 steers the wheels of the electric vehicle 100. The drive system 110 can also be referred to as a powertrain.

[0053] The braking system 120 can be an electro-hydraulic braking system (EHB) or an electro-mechanical braking system (EMB). Because EMB offers advantages over EHB such as faster response, higher precision, and no fluid leakage, it significantly improves safety performance while offering greater flexibility in deployment and lower maintenance costs. Therefore, EMB is now widely used instead of EHB.

[0054] Based on their position within the electric vehicle 100, the wheels can be categorized as follows: left front wheel (FL), right front wheel (FR), left rear wheel (BL), and right rear wheel (BR). In terms of axle arrangement, the left and right front wheels are coaxial and connected via the front axle. The left and right rear wheels are coaxial and connected via the rear axle. In terms of position, the left and left rear wheels are on the same side (left side), and the right front and right rear wheels are on the same side (right side). In other words, in the electric vehicle 100, the left and right front wheels are coaxial, as are the left and right rear wheels; the left and left rear wheels are on the same side, as are the right and right rear wheels.

[0055] The electric vehicle 100 in this application embodiment can be any of different types of automobiles such as cars, trucks, and passenger buses, or it can be a tricycle, two-wheeled vehicle, train, or other transportation device that carries people or goods, or other types of vehicles powered by power batteries. This application embodiment does not limit this.

[0056] See Figure 3 , Figure 3 A schematic diagram of an electric vehicle architecture provided in an embodiment of this application is shown. Figure 3 The electric vehicle 100 shown is a four-wheel drive model.

[0057] like Figure 3 As shown, drive system 110 (such as Figure 2 (As shown) includes a drive motor 111 for the left front wheel and a motor controller 112 for the drive motor 111, a drive motor 113 for the right front wheel and a motor controller 114 for the drive motor 113, a drive motor 115 for the left rear wheel and a motor controller 116 for the drive motor 115, and a drive motor 117 for the right rear wheel and a motor controller 118 for the drive motor 117.

[0058] When the electric vehicle 100 is in a driving state, each drive motor in the drive system 110 provides driving force to the electric vehicle 100. Specifically, when the electric vehicle 100 is in a driving state, the vehicle controller 140 calculates the torque demand of the electric vehicle and outputs torque signals to the motor controllers of each drive motor. Each motor controller receives torque signals from the power battery 130 (e.g., ...). Figure 2 The electric energy (as shown) is used to control the corresponding drive motor output torque signal indicating the drive torque, which is in the same direction as the wheels rotate when the electric vehicle moves forward.

[0059] Continue to refer to Figure 3 The braking system 120 (such as Figure 2 As shown, it mainly includes the brake pedal ( Figure 3(Not shown in the diagram) A central controller 121 and four wheel-end braking devices 122. The four wheel-end braking devices 122 are used to brake the four wheels of the electric vehicle.

[0060] When the electric vehicle 100 is in a braking state, the wheel-end braking devices in the braking system 120 are used to provide braking force to the electric vehicle 100. Specifically, when the electric vehicle 100 is in a braking state, the central controller 121 can generate a braking signal and, based on the braking signal, control one or more of the four wheel-end braking devices 122 to output the braking torque indicated by the braking signal to the corresponding wheel. The braking torque is opposite to the direction of wheel rotation when the electric vehicle is moving forward, so as to prevent the wheel from rotating or to prevent the wheel from rotating.

[0061] Each wheel-end braking device 122 includes a wheel-end controller and a wheel-end actuator (e.g., a brake motor and a brake caliper). For each wheel, the wheel-end controller, in response to a brake signal received from the central controller, controls the wheel-end actuator to output braking force to the brake disc to brake the wheel. For example, the wheel-end controller controls the brake motor to output braking torque to drive the brake caliper to clamp the brake disc.

[0062] In particular, each drive motor in the electric vehicle 100 with energy recovery function can also be used to provide braking force for the electric vehicle 100. Specifically, when the electric vehicle 100 is in a braking state, the vehicle controller 140 receives a braking signal and sends an energy recovery command to each motor controller. Each motor controller responds to the energy recovery command and controls the corresponding drive motor to operate in a power generation state. Each drive motor converts the kinetic energy of the electric vehicle's wheels into electrical energy and outputs braking torque to the wheels of the electric vehicle 100 to provide braking force for the electric vehicle 100.

[0063] The drive system 110, braking system 120, and vehicle controller 140 are connected via a CAN network, and this embodiment does not limit the specific communication connection method. For example, the motor controller in the drive system 110 and the vehicle controller 140 can communicate via a private CAN network, the central controller 121 of the braking system 120 and the vehicle controller 140 can communicate via a public CAN network, and the central controller 121 and each wheel-end braking device 122 can communicate via another private CAN network. Alternatively, the vehicle controller 140 can communicate with the motor controller in the drive system 110 and the central controller 121 in the braking system 120 via the same CAN network.

[0064] See Figure 4 , Figure 4 A schematic diagram of another electric vehicle architecture provided in an embodiment of this application is shown.

[0065] Figure 4 The steering system 150 shown in (a) includes a steering motor 141 for two front wheels, a steering controller 142 and a steering actuator 143 for the steering motor 141, a steering motor 144 for two rear wheels, a steering controller 145 and a steering actuator 146 for the steering motor 144.

[0066] Steering motor 141 provides driving force for steering the two front wheels, and steering motor 144 provides driving force for steering the two rear wheels. Steering controller 142 controls the output torque of steering motor 141, and steering controller 145 controls the output torque of steering motor 144. Steering actuator 143 converts the rotational motion of the output torque of steering motor 141 into linear motion to drive the two front wheels to steer, and steering actuator 146 converts the rotational motion of the output torque of steering motor 144 into linear motion to drive the two front wheels to steer. In other words, one steering controller controls one steering motor to output torque to drive one steering actuator to steer one wheel.

[0067] During the steering process of the electric vehicle, the steering controller 142 receives the steering angle signal from the vehicle controller 140 and the signal from the power battery 130 (e.g., Figure 2 The electrical energy (as shown) is used to control the steering motor 141 to output torque according to the steering angle indicated by the steering angle signal, driving the steering actuator 143 to steer the two front wheels. The steering controller 145 receives the steering angle signal from the vehicle controller 140 and receives the electrical energy from the power battery 130 (as shown). Figure 2 The electrical energy (shown) controls the output torque of the steering motor 144 according to the steering angle indicated by the steering angle signal, driving the steering actuator 146 to steer the two rear wheels.

[0068] The steering motors 141 and 144 output torque in the same direction, and the two wheels they drive steer in the same direction. Each output torque includes a forward torque and a reverse torque. When the steering motor outputs forward torque and reverse torque, the wheels steer in opposite directions. For example, when the steering motor outputs forward torque, the wheel it drives steers to the left, and when it outputs reverse torque, the wheel it drives steers to the right.

[0069] Figure 4The steering system 150 shown in (b) is a four-wheel independent steering system, including a steering motor 147 for the left front wheel, a steering controller 148 and a steering actuator 149 for the steering motor 147, a steering motor 151 for the right front wheel, a steering controller 152 and a steering actuator 153 for the steering motor 151, a steering motor 154 for the left rear wheel, a steering controller 155 and a steering actuator 156 for the steering motor 154, and a steering motor 157 for the right rear wheel, a steering controller 158 and a steering actuator 159 for the steering motor 157.

[0070] One steering motor provides driving force for steering one wheel. A steering controller controls the output torque of the steering motor. A steering actuator converts the rotational motion of the steering motor's output torque into linear motion, driving the steering of one wheel. Specifically, a steering controller controls the output torque of the steering motor to drive a steering actuator to steer one wheel; for example, steering controller 148 controls the output torque of steering motor 147 to drive steering actuator 149 to steer the left front wheel.

[0071] The steering system 150 and the vehicle controller 140 are connected via communication, and the specific communication connection method is not limited in this embodiment. For example, the steering controller in the steering system 150 and the vehicle controller 140 can communicate via a private CAN network, or they can communicate via a public CAN network.

[0072] The architecture of the embodiments of this application has been described above. The control method for electric vehicles provided by this application will be described below with reference to specific embodiments.

[0073] This application provides a control method for an electric vehicle, which avoids the electric vehicle from veering off course by controlling the coordination of the steering system and the drive system or braking system during the electric vehicle's travel on a split road.

[0074] Among them, when an electric vehicle is driving on a split road, the difference between the adhesion coefficient between the left wheel and the road surface and the adhesion coefficient between the right wheel and the road surface is greater than the preset value. That is, the adhesion coefficients between the two wheels on the same axle and the road surface are different and the difference is large. For example, one wheel on the same axle is driving on sand, and the other wheel is driving on asphalt.

[0075] The electric vehicle control method provided in this application includes the following steps.

[0076] Before the electric vehicle enters the split road, the steering angle of the two front wheels of the electric vehicle changes with the steering wheel angle.

[0077] Before the electric vehicle enters the split road surface, that is, before the electric vehicle enters the split road surface, the difference in the coefficient of adhesion between the two wheels on the same axle and the road surface is less than the preset value. This means that the coefficient of adhesion between the two wheels on the same axle is the same or the difference is small. For example, if the two wheels on the same axle are traveling on an asphalt road, the uniform road surface provides the two wheels on the same axle with the same or small grip.

[0078] Before the electric vehicle enters the parallel road, the angle of the two front wheels of the electric vehicle is controlled according to the angle of the steering wheel, so that the driver can accurately control the driving trajectory of the electric vehicle by operating the steering wheel.

[0079] In one embodiment, for such Figure 4 The four-wheel independent steering system shown in (b) can independently control the steering angle of the four wheels of an electric vehicle according to the steering wheel angle, that is, the steering angle of the two rear wheels also changes with the steering wheel angle.

[0080] Before an electric vehicle enters a split road surface, the drive system is controlled to supply drive torque to the wheels of the electric vehicle based on the opening of the accelerator pedal, or the braking system is controlled to supply braking torque to the wheels of the electric vehicle based on the opening of the brake pedal.

[0081] For ease of understanding, see Figure 5 and Figure 6 , Figure 5 This illustration shows a schematic diagram of a driving scenario for an electric vehicle according to an embodiment of this application. Figure 6 This illustration shows a timing diagram relating the accelerator pedal opening, drive torque, and steering angle of the two front wheels, according to an embodiment of this application. Figure 6 Taking the straight-line driving condition of an electric vehicle as an example, Figure 5 The shade of color in the image indicates the coefficient of adhesion of the road surface; the darker the color, the greater the coefficient of adhesion.

[0082] like Figure 5 As shown, before the electric vehicle enters the split road surface, the road surface where the wheels of the electric vehicle are located is the same color, that is, the adhesion coefficient between the left wheel and the road surface is equal to the adhesion coefficient between the right wheel and the road surface.

[0083] like Figure 6 As shown, before the first moment t1 when the electric vehicle enters the split road, the opening of the accelerator pedal remains unchanged, the driving torque output by the drive system to one right wheel is equal to the driving torque output to one left wheel on the same axle, the two front wheels do not turn, and their turning angle is zero.

[0084] In one embodiment, the control method further includes: after the electric vehicle enters the split road surface and before it leaves the split road surface, controlling the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle to increase, and actively controlling the steering angle of the two front wheels to increase or decrease.

[0085] After an electric vehicle enters a split road surface, the longitudinal force limit that the grip of the low-tether wheel can provide is less than that that of the high-tether wheel. By controlling the increase of the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle, the driving torque or braking torque of the low-tether wheel is prevented from exceeding the longitudinal force limit of that wheel, causing it to slip. At the same time, the greater driving torque or braking torque of the high-tether wheel ensures the driving or braking capability of the electric vehicle.

[0086] In one embodiment, controlling the increase of the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle can be achieved by gradually increasing the difference between the driving torque or braking torque between the left wheel and the right wheel on the same axle. That is, controlling the difference between the braking torque or driving torque between the left wheel and the right wheel on the same axle to increase at a preset rate avoids a sudden increase in the difference between the driving torque or braking torque of the two wheels on the same axle, which would cause large fluctuations in the yaw moment of the electric vehicle. This avoids the electric vehicle from suddenly fishtailing or yawing, and improves the comfort of the ride.

[0087] In one embodiment, the difference between the driving torque or braking torque of the two coaxial wheels can be gradually increased by controlling the driving torque or braking torque of a left wheel and a coaxial right wheel to increase or decrease at a specified rate.

[0088] As the difference between the driving torque or braking torque of the two wheels on the same axle increases, the electric vehicle will generate a yaw moment that increases accordingly, causing the vehicle to yaw.

[0089] In this situation, by actively controlling the increase or decrease of the steering angle of the two front wheels, that is, without the driver actively turning the steering wheel, the steering angle of the two front wheels is actively controlled to increase or decrease, so as to actively balance the yaw moment generated by the change of the yaw moment generated by the lateral force of the two front wheels, which is caused by the difference between the driving torque or the braking torque, thus avoiding the yaw of the electric vehicle.

[0090] In one embodiment, the steering angle of the two front wheels is actively controlled to increase or decrease as the braking torque or driving torque between the two wheels on the same axle increases. The steering of the two front wheels is precisely controlled according to the difference between the driving torque and the braking torque, so as to accurately balance the yaw moment caused by the difference between the driving torque and the braking torque through the change of the lateral force of the wheels, thereby improving the accuracy of active control.

[0091] Actively controlling the increase or decrease of the steering angle of the two front wheels means that when the controller of the electric vehicle senses an increase in the difference between the driving torque and braking torque of the two wheels on the same axle while the electric vehicle is traveling on a split road, it actively issues a command to control the increase or decrease of the steering angle of the two front wheels of the electric vehicle, rather than responding to the input of the driver operating the steering wheel to control the change of the steering angle of the two front wheels.

[0092] See also Figure 5 and Figure 6 ,like Figure 5 As shown in position 2, after the electric vehicle enters the split road surface, the color of the road surface where the left wheel is located is lighter than the color of the road surface where the right wheel is located, that is, the adhesion coefficient between the left wheel and the road surface is less than the adhesion coefficient between the right wheel and the road surface.

[0093] In this case, such as Figure 6 As shown, after the first moment t1 when the electric vehicle enters the split road and before the second moment t2 when the electric vehicle leaves the split road, the opening of the accelerator pedal remains unchanged. The driving torque output by the drive system to one right wheel is greater than the driving torque output to one left wheel on the same axle, and the difference in driving torque increases. The rightward turning angle of the two front wheels increases with the increase in the difference in driving torque.

[0094] In one embodiment, the difference in drive torque between a left wheel and a coaxial right wheel can be controlled to increase throughout the entire time period between the first time t1 and the second time t2, or the difference in drive torque between a left wheel and a coaxial right wheel can be controlled to increase during a portion of the time period between the first time t1 and the second time t2 (e.g., Figure 6 (As shown). In other words, the action of increasing the difference in drive torque between a left wheel and a right wheel on the same axle occurs at any time between the first time t1 and the second time t2.

[0095] In this embodiment of the application, for ease of understanding, the difference between the driving torque or braking torque shown in the illustration is the driving torque or braking torque of one left wheel minus the driving torque or braking torque of one right wheel. Therefore, the difference between the driving torque or braking torque may be positive or negative (e.g., Figure 6 (As shown).

[0096] In this embodiment, before the electric vehicle enters the parallel road surface, the steering angles of the two front wheels are controlled to change with the steering wheel angle, allowing the driver to precisely control the vehicle's trajectory by operating the steering wheel. After the electric vehicle enters the parallel road surface but before leaving, the difference in driving torque or braking torque between one left wheel and one right wheel on the same axle is increased to prevent the driving torque or braking torque of the lower-attached wheel from exceeding its longitudinal force limit, thus preventing wheel slippage and affecting the vehicle's driving stability. Simultaneously, the higher-attached wheel provides greater driving or braking torque to ensure the vehicle's driving or braking capabilities. Furthermore, by actively controlling the steering angles of the two front wheels—that is, actively controlling the steering angles of the two front wheels without the driver actively turning the steering wheel—the yaw moment generated by the lateral forces of the two front wheels is actively balanced by the change in yaw moment caused by the difference in driving torque or braking torque. This coordinated control of the steering system and the drive or braking system prevents the electric vehicle from yawing.

[0097] In this embodiment, for a three-wheel drive vehicle, the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle is increased, that is, the difference between the driving torque or braking torque between coaxial wheels controlled separately by two drive motors is increased; for a four-wheel drive vehicle, the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle is increased, which may be the difference between the driving torque or braking torque between the two front wheels and / or the two rear wheels.

[0098] In one embodiment, the control method further includes: after the electric vehicle leaves the road surface, controlling the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle to decrease, and actively controlling the steering angle of the two front wheels to decrease or increase.

[0099] After the electric vehicle leaves the parallel road surface, the difference between the driving torque or braking torque between one left wheel and one right wheel on the same axle is reduced, and the steering angle of the two front wheels is actively controlled to decrease or increase. This releases the control of the electric vehicle's torque and the steering angle of the two front wheels from the control after entering the parallel road surface, preventing the electric vehicle from yawing due to the control remaining on the parallel road surface after leaving it, so that the electric vehicle can return to normal driving status.

[0100] See also Figure 5 and Figure 6 ,like Figure 5 As shown in position 3, after the electric vehicle leaves the road surface, the colors of the road surface where the wheels of the electric vehicle are located are the same, that is, the adhesion coefficient between the left wheel and the road surface is equal to the adhesion coefficient between the right wheel and the road surface.

[0101] like Figure 6As shown, after the electric vehicle leaves the opposite road surface at the second moment t2, the difference between the driving torque output by the drive system to one right wheel and the driving torque output to one left wheel on the same axle decreases, and the steering angle of the two front wheels decreases as the difference in driving torque decreases.

[0102] In one embodiment, the rate of decrease of the difference between the drive torque or braking torque between a left wheel and a coaxial right wheel can be greater than the rate of increase of the difference between the drive torque or braking torque between a left wheel and a coaxial right wheel, thereby achieving smooth entry into control and rapid exit from control.

[0103] In this embodiment, after the electric vehicle leaves the parallel road surface, the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle is reduced, and the steering angle of the two front wheels is actively reduced or increased. This releases the control of the electric vehicle's torque and the steering angle of the two front wheels after entering the parallel road surface, preventing the electric vehicle from remaining on the parallel road surface after leaving it and causing it to yaw, thus allowing the electric vehicle to return to normal driving status.

[0104] For electric vehicles braking and straight-line driving conditions, see Figure 7 , Figure 7 This paper presents a timing diagram showing the opening degree of a brake pedal, braking torque, and the steering angle of the two front wheels according to an embodiment of this application.

[0105] Before the electric vehicle enters the split road at the first moment t1, the opening of the brake pedal remains unchanged, the braking torque output by the braking system to one right wheel is equal to the braking torque output to one left wheel on the same axle, the two front wheels do not turn, and their turning angle is zero.

[0106] After the electric vehicle enters the split road at the first moment t1 and before the electric vehicle leaves the split road at the second moment t2, the opening of the brake pedal remains unchanged. The difference between the braking torque output by the braking system to one right wheel and the braking torque output to one left wheel on the same axle increases, and the turning angle of the two front wheels increases with the increase of the difference in braking torque.

[0107] After the electric vehicle leaves the opposite road surface at the second moment t2, the opening of the brake pedal remains unchanged. The difference between the braking torque output by the braking system to one right wheel and the braking torque output to one left wheel on the same axle decreases. The leftward turning angle of the two front wheels decreases as the difference in braking torque decreases.

[0108] In one embodiment, the difference in braking torque between a left wheel and a coaxial right wheel can be controlled to increase throughout the entire time period between a first time t1 and a second time t2 (e.g., Figure 6As shown, it is also possible to control the increase of the difference in braking torque between a left wheel and a right wheel on the same axle during a certain period between the first time t1 and the second time t2. In other words, the action of controlling the increase of the difference in braking torque between a left wheel and a right wheel on the same axle can occur at any time between the first time t1 and the second time t2.

[0109] In one embodiment, the control method specifically includes: after the electric vehicle enters the split road surface and before it leaves the split road surface, controlling the difference between the driving torque or braking torque of one left wheel and one right wheel to increase, and actively controlling the steering angle of the two front wheels to increase or decrease before the steering wheel angle changes.

[0110] In a steer-by-wire system, the steering wheel and the two front wheels are connected by electrical signals, but there is no physical connection. The increase or decrease in the steering angle of the two front wheels is not transmitted to the steering wheel and is not reflected in the change of the steering wheel angle. In other words, the steering wheel angle does not change with the change of the steering angle of the two front wheels.

[0111] For ease of understanding, see Figure 8 , Figure 8 This illustration shows a timing diagram relating the difference in drive torque, the steering angles of the two front wheels, and the steering wheel angle, as provided in an embodiment of this application. Figure 8 Take the straight-line driving condition of an electric vehicle as an example.

[0112] like Figure 8 As shown, before the electric vehicle enters the split road at the first moment t1, the driving torque output by the drive system to one right wheel is equal to the driving torque output to one left wheel on the same axle. The two front wheels do not turn, their turning angle is zero, and the steering wheel turning angle is zero.

[0113] After the electric vehicle enters the split road at the first moment t1 and before the electric vehicle leaves the split road at the second moment t2, the difference between the driving torque output by the drive system to one right wheel and the driving torque output to one left wheel on the same axle increases. The rightward turning angle of the two front wheels increases with the increase of the difference in driving torque, and the steering wheel angle is zero.

[0114] After the electric vehicle leaves the opposite road surface at the second moment t2, the difference between the driving torque output by the drive system to one right wheel and the driving torque output to one left wheel on the same axle decreases. The steering angle of the two front wheels decreases as the difference in driving torque decreases, and the steering wheel angle is zero.

[0115] In such Figure 8 Throughout the entire control process shown, the steering wheel angle remains unchanged regardless of the steering angle of the two front wheels or the difference in driving torque or braking torque between the two wheels on the same axle.

[0116] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the steering angle of the two front wheels is actively controlled to increase or decrease before the steering wheel angle changes. That is, during the electric vehicle's travel on the parallel road surface, the steering angle changes of the two front wheels are not transmitted to the steering wheel. The driver still operates the steering wheel according to the desired driving trajectory, avoiding tension and anxiety caused by the steering wheel turning on its own, thus improving driving comfort.

[0117] In one embodiment, the control method specifically includes: after the electric vehicle enters the split road surface and before it leaves the split road surface, controlling the difference between the driving torque or braking torque of one left wheel and one right wheel to increase, and actively controlling the steering wheel angle to change with the change of the steering angle of the two front wheels.

[0118] In a mechanical steering system, the steering wheel and the two front wheels are physically rigidly connected. An increase or decrease in the steering angle of the two front wheels will inevitably be transmitted to the steering wheel through the connecting components (such as the steering column, drive shaft, etc.), and will be reflected in the change of the steering wheel angle.

[0119] In a steer-by-wire system, the steering wheel and the two front wheels are connected by an electrical signal. An increase or decrease in the steering angle of the two front wheels can be transmitted to the steering wheel, which is reflected in the change of the steering wheel angle.

[0120] For ease of understanding, see Figure 9 , Figure 9 This illustration shows a timing diagram between the difference in drive torque, the steering angle of the two front wheels, and the steering wheel angle, as provided in another embodiment of this application. Figure 9 Take the straight-line driving of an electric vehicle as an example.

[0121] like Figure 9 As shown, before the electric vehicle enters the split road at the first moment t1, the driving torque output by the drive system to one right wheel is equal to the driving torque output to one left wheel on the same axle. The two front wheels do not turn, their turning angle is zero, and the steering wheel turning angle is zero.

[0122] After the electric vehicle enters the split road at the first moment t1 and before the electric vehicle leaves the split road at the second moment t2, the difference between the driving torque output by the drive system to one right wheel and the driving torque output to one left wheel on the same axle increases. The turning angle of the two front wheels increases with the increase of the difference in driving torque, and the turning angle of the steering wheel increases with the increase of the rightward turning angle of the two front wheels.

[0123] After the electric vehicle leaves the opposite road surface at the second moment t2, the difference between the driving torque output by the drive system to one right wheel and the driving torque output to one left wheel on the same axle decreases. The turning angle of the two front wheels decreases as the difference in driving torque decreases, and the turning angle of the steering wheel decreases as the turning angle of the two front wheels decreases.

[0124] In such Figure 9 Throughout the control process shown, the steering wheel angle changes with the steering angle of the two front wheels and the difference between the driving torque or braking torque of the two wheels on the same axle.

[0125] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the steering wheel angle is actively controlled to change with the steering angle of the two front wheels. That is, during the electric vehicle's travel on the parallel road surface, the steering angle changes of the two front wheels are transmitted to the steering wheel, allowing the driver to feel the changes in the steering angle of the two front wheels and to be aware of the active control operations performed by the electric vehicle. This improves the trust between the driver and the electric vehicle and facilitates the driver in performing other driving operations.

[0126] The following will provide a detailed explanation of the control of the drive system or braking system of electric vehicles during their operation on split-level roads.

[0127] In one embodiment, the control method specifically includes: before controlling the difference between the drive torque or braking torque of a left wheel and a right wheel to increase, controlling the difference between the drive torque or braking torque of a left wheel and a right wheel to decrease.

[0128] This means that before increasing the difference in driving torque or braking torque between two wheels on the same axle, the existing difference in braking torque or driving torque should be reduced to decrease initial yaw disturbance and allow the electric vehicle to be in a highly stable state.

[0129] In this situation, by controlling the increase in the difference between the driving torque or braking torque of one left wheel and one right wheel, it is possible to prevent the grip of the two wheels, especially the low-touch wheel, from exceeding the friction limit due to a direct increase in the difference in driving torque or braking torque between the two wheels on the same axle, thus avoiding loss of control of the electric vehicle. Furthermore, it facilitates the redistribution of the difference in driving torque or braking torque between the two wheels by the drive system, better preventing the electric vehicle from yawing.

[0130] In one embodiment, before increasing the difference between the drive torque or braking torque of a left wheel and a right wheel, if the difference between the drive torque or braking torque of a left wheel and a right wheel is greater than a preset difference, the difference between the drive torque or braking torque of a left wheel and a right wheel is first controlled to decrease.

[0131] If the difference between the driving torque or braking torque of one left wheel and one right wheel is greater than a preset difference, it indicates a large difference in the driving torque or braking torque of the two wheels, resulting in poor stability of the electric vehicle. In this case, reducing the difference in driving torque or braking torque between the two wheels first can prevent the electric vehicle from losing control and avoid performing related controls when the difference in driving torque or braking torque between the two wheels is small, thus saving control costs.

[0132] In this embodiment, after the electric vehicle enters the split-path surface but before leaving it, before increasing the difference in driving torque or braking torque between one left wheel and one right wheel, the difference is first reduced. This reduces the existing difference in driving torque or braking torque, lowering the initial yaw disturbance. This prevents the difference in driving torque or braking torque between the two wheels on the same axle from directly increasing, causing the grip of the two wheels, especially the low-touch wheel, to exceed the friction limit, thus preventing the electric vehicle from losing control. Simultaneously, it facilitates the redistribution of the driving torque or braking torque difference between the two wheels in the drive system, better preventing the electric vehicle from yawing.

[0133] In one embodiment, the control method specifically includes: before increasing the difference between the driving torque or braking torque of a left wheel and a right wheel, controlling the driving torque or braking torque of a left wheel and a right wheel to decrease simultaneously.

[0134] Before increasing the difference in driving torque or braking torque between two coaxial wheels, the longitudinal force demand of the two coaxial wheels should be released first to avoid the grip of the two wheels exceeding the friction limit due to the increase in the difference in driving torque or braking torque between the two coaxial wheels.

[0135] In one embodiment, controlling the driving torque or braking torque of a left wheel and a right wheel to decrease simultaneously may include: controlling the driving torque or braking torque of a left wheel and a right wheel to decrease simultaneously to a preset torque value.

[0136] The preset torque value can be a specified value or the torque value of the wheel on the side with a smaller coefficient of adhesion, which increases as the coefficient of adhesion increases.

[0137] When the preset torque value is specified, the difference between the driving torque or braking torque of one left wheel and one right wheel is increased, that is, the driving torque or braking torque of one left wheel and one right wheel is increased simultaneously, and the rate of increase of the driving torque or braking torque of the higher-attached wheel is greater than the rate of increase of the driving torque or braking torque of the lower-attached wheel.

[0138] When the preset torque value is the torque value of the low-attached wheel, the difference between the driving torque or braking torque of a left wheel and a right wheel is increased, that is, the driving torque or braking torque of the low-attached wheel is kept constant, and the driving torque or braking torque of the high-attached wheel is increased.

[0139] For better understanding, please continue to refer to [link / reference]. Figure 6 and Figure 7 ,like Figure 6 As shown, after the electric vehicle enters the split road surface at the first moment t1, the driving torque of one left wheel and one right wheel is first controlled to decrease simultaneously, then the driving torque of one left wheel is kept constant while the driving torque of one right wheel is increased. The change in braking torque can be further explained in [reference needed]. Figure 7 .

[0140] In this embodiment, after the electric vehicle enters the split road surface and before it leaves the split road surface, before the difference between the driving torque or braking torque of one left wheel and one right wheel increases, the driving torque or braking torque of one left wheel and one right wheel is reduced simultaneously first. This releases the longitudinal force demand of the two wheels on the same axle, and avoids the grip force of the two wheels exceeding the friction limit due to the increase in the difference between the driving torque or braking torque of the two wheels on the same axle, which would cause the electric vehicle to lose control.

[0141] In one embodiment, the control method specifically includes: first controlling the duration for which the driving torque or braking torque of a left wheel and a right wheel decreases simultaneously to be less than the duration for which the duration for which the difference between the driving torque or braking torque of a left wheel and a right wheel increases is less than the duration for which ...

[0142] That is, first control the driving torque or braking torque of the two wheels on the same axle to decrease at a large rate, and then control the difference between the driving torque or braking torque of the two wheels on the same axle to gradually increase at a small rate.

[0143] For better understanding, please continue to refer to [link / reference]. Figure 6 and Figure 7 ,like Figure 6 As shown, after the electric vehicle enters the split road surface at the first moment t1, the curve slope for the portion where the driving torque of one left wheel and one right wheel decreases simultaneously is relatively large, while the curve slope for the portion where the driving torque of one left wheel and one right wheel increases is relatively small. That is, the duration of the simultaneous decrease in the driving torque of one left wheel and one right wheel is less than the duration of the increase in the difference between the driving torques of one left wheel and one right wheel. The change in braking torque can be further explained by referring to... Figure 7 .

[0144] In this embodiment, after the electric vehicle enters the parallel road surface and before it leaves, the duration for which the driving torque or braking torque of one left wheel and one right wheel decreases simultaneously is less than the duration for which the difference between the driving torque or braking torque of one left wheel and one right wheel increases. This allows for a rapid response to the electric vehicle entering the parallel road surface by reducing torque and preventing slippage of the low-tether wheel. Additionally, the difference between the driving torque or braking torque of the two wheels on the same axle is gradually increased to prevent a sudden increase in the difference, which could cause large fluctuations in the yaw moment of the electric vehicle. This avoids sudden tail-swing or yaw of the electric vehicle and improves driving comfort.

[0145] In one embodiment, the control method specifically includes: the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference between the driving torque or braking torque of a left wheel and a right wheel.

[0146] The greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference in the longitudinal force limit that the grip of the two wheels on the same axle can provide.

[0147] In this situation, by controlling the difference between the driving torque or braking torque between a left wheel and a right wheel on the same axle, the greater the difference between the driving torque or braking torque between the two wheels, the greater the yaw moment generated by the difference between the driving torque or braking torque of the two wheels. This prevents the driving torque or braking torque of the lower-attached wheel from exceeding the longitudinal force limit of that wheel, causing the wheel to slip and affecting the driving stability of the electric vehicle. At the same time, the greater driving torque or braking torque of the higher-attached wheel ensures the driving capability or braking capability of the electric vehicle.

[0148] In this embodiment, the greater the difference in the coefficient of adhesion between a left wheel and the road surface compared to the right wheel, the more prone the electric vehicle is to yaw. In this case, by controlling the difference in driving torque or braking torque between a left wheel and a right wheel to a greater extent, the driving torque or braking torque of the lower-adhesion wheel is prevented from exceeding its longitudinal force limit, thus avoiding wheel slippage. Meanwhile, the higher-adhesion wheel provides greater driving torque or braking torque to ensure the electric vehicle's driving or braking capabilities. This allows for flexible control of the difference in driving torque or braking torque between the two coaxial wheels and the road surface based on the difference in their coefficients of adhesion. Consequently, under varying coefficients of adhesion differences, slippage of the lower-adhesion wheel can be avoided while the higher-adhesion wheel maintains the electric vehicle's driving or braking capabilities.

[0149] See Figure 10 , Figure 10 A flowchart of a control method for an electric vehicle provided in an embodiment of this application is shown.

[0150] like Figure 10 As shown, firstly, the torque (braking torque or driving torque) output to each wheel is calculated based on the pedal opening (brake pedal opening or accelerator pedal opening); then, it is determined whether the electric vehicle has entered the split road surface, that is, whether the difference between the adhesion coefficient between one left wheel and the road surface and the adhesion coefficient between one right wheel on the same axle and the road surface is greater than a preset value.

[0151] If so, that is, when an electric vehicle enters a split road, reduce the torque of the wheel on the higher attachment side to make it the same as the torque of the wheel on the lower attachment side, and then gradually increase the torque of the wheel on the higher attachment side, while simultaneously increasing the steering angle of the two front wheels.

[0152] If not, meaning the electric vehicle has not entered the opposite road surface, the control provided in this application embodiment ends.

[0153] The following will provide a detailed explanation of the active control of the steering system during the driving of an electric vehicle on a split-road surface. The example used is a split-road surface where the coefficient of friction between one left wheel and the road surface is less than that between one right wheel and the road surface. The situation is entirely similar when the coefficient of friction between one left wheel and the road surface is greater than that between one right wheel and the road surface, and will not be elaborated upon here.

[0154] When driving on a road surface where the coefficient of friction between the left wheel and the road surface is less than that between the right wheel and the road surface, the electric vehicle will veer to the left.

[0155] In one embodiment, the control method specifically includes: when the electric vehicle is traveling straight on a split road, if the opening of the accelerator pedal is greater than a preset accelerator pedal opening, controlling the driving torque of one left wheel to be less than the driving torque of one right wheel, and actively controlling the two front wheels to turn to the right.

[0156] If the accelerator pedal is opened to a degree greater than the preset accelerator pedal opening, it indicates that the driver intends to operate the accelerator pedal to drive the electric vehicle.

[0157] When an electric vehicle is driving straight, if the driving torque of one left wheel is less than that of one right wheel, the difference in driving torque between the two wheels on the same axle will generate a counterclockwise yaw moment, causing the electric vehicle to yaw.

[0158] In this situation, by actively controlling the two front wheels to turn right, the clockwise yaw moment generated by the lateral force of the wheels when the two front wheels turn right actively balances the counterclockwise yaw moment generated by the difference in drive torque.

[0159] In one embodiment, the rightward steering angle of the two front wheels is controlled to increase as the difference in drive torque between the two wheels on the same axle increases, thereby achieving precise balance of yaw moment.

[0160] In this embodiment, while the electric vehicle is traveling straight on a split road, the system automatically detects the driver's intention to operate the accelerator pedal to drive the electric vehicle by detecting that the accelerator pedal opening is greater than a preset accelerator pedal opening. In this case, by controlling the driving torque of one left wheel to be less than that of one right wheel, and the driving torque of the lower-tether wheel to be less than that of the higher-tether wheel, slippage of the lower-tether wheel is avoided while the driving capability of the electric vehicle is maintained by the higher-tether wheel. Furthermore, by actively controlling the two front wheels to steer to the right, the clockwise yaw moment generated by the lateral force of the two front wheels when steer to the right can actively balance the counterclockwise yaw moment generated by the difference in driving torque, thus preventing the electric vehicle from yawing.

[0161] In one embodiment, the control method specifically includes: when the electric vehicle is traveling straight on a split road, if the opening of the brake pedal is greater than a preset brake pedal opening, controlling the braking torque of one left wheel to be less than the braking torque of one right wheel, and actively controlling the two front wheels to turn to the left.

[0162] If the brake pedal is open more than the preset brake pedal opening, it indicates that the driver intends to operate the brake pedal to brake the electric vehicle.

[0163] When an electric vehicle is braking and traveling straight, by controlling the driving torque of one left wheel to be less than the driving torque of one right wheel, the difference in driving torque between the two wheels on the same axle generates a clockwise yaw moment, causing the electric vehicle to yaw.

[0164] In this situation, by actively controlling the two front wheels to steer to the left, the counterclockwise yaw moment generated by the lateral force of the wheels when the two front wheels steer to the left is actively balanced by the clockwise yaw moment generated by the difference in braking torque.

[0165] In one embodiment, the leftward steering angle of the two front wheels is controlled to increase as the difference in drive torque between the two wheels on the same axle increases, thereby achieving precise balance of yaw moment.

[0166] In this embodiment, while the electric vehicle is traveling straight on a split road, the system automatically detects the driver's intention to brake by detecting that the brake pedal opening is greater than a preset brake pedal opening. In this case, by controlling the braking torque of one left wheel to be less than that of one right wheel, and the braking torque of the lower-tethered wheel to be less than that of the higher-tethered wheel, the system avoids slippage on the lower-tethered wheel while maintaining the braking capability of the electric vehicle through the higher-tethered wheel. Furthermore, by actively controlling the two front wheels to steer to the left, the counterclockwise yaw moment generated by the lateral force of the two front wheels when steer to the left actively balances the clockwise yaw moment generated by the difference in braking torque, thus preventing the electric vehicle from yawing.

[0167] In one embodiment, the control method specifically includes: when the electric vehicle is turning left on a road with two wheels facing each other, when the opening of the accelerator pedal is greater than a preset accelerator pedal opening, controlling the driving torque of one left wheel to be less than the driving torque of one right wheel, and actively controlling the leftward turning angle of the two front wheels to decrease.

[0168] When an electric vehicle is turning left, by controlling the driving torque of one left wheel to be less than that of one right wheel, the difference in driving torque between the two wheels on the same axle generates a counterclockwise yaw moment, causing the electric vehicle to yaw.

[0169] In this situation, by actively controlling the leftward turning angle of the two front wheels to reduce the counterclockwise yaw moment generated by the lateral force of the two front wheels, the total yaw moment of the electric vehicle remains unchanged, thus preventing the electric vehicle from yawing.

[0170] In this embodiment, during the left turn of the electric vehicle on a road surface, by controlling the driving torque of one left wheel to be less than that of one right wheel, and the driving torque of the lower-tethered wheel to be less than that of the higher-tethered wheel, slippage of the lower-tethered wheel is avoided while the driving capability of the electric vehicle is maintained by the higher-tethered wheel. Furthermore, by actively controlling the leftward turning angle of the two front wheels to decrease, and considering the counterclockwise yaw moment generated by the difference in driving torque between the two wheels on the same axle, the counterclockwise yaw moment generated by the lateral force of the two front wheels is reduced, keeping the total yaw moment of the electric vehicle constant and preventing yaw.

[0171] In one embodiment, the control method specifically includes: when the electric vehicle is turning left on a road with two wheels facing each other, when the opening of the brake pedal is greater than a preset brake pedal opening, controlling the braking torque of one left wheel to be less than the braking torque of one right wheel, and actively controlling the leftward turning angle of the two front wheels to increase.

[0172] When an electric vehicle brakes to make a left turn, by controlling the braking torque of one left wheel to be less than that of one right wheel, the difference in braking torque between the two wheels on the same axle generates a clockwise yaw moment, causing the electric vehicle to yaw.

[0173] In this situation, by actively controlling the leftward turning angle of the two front wheels to increase, the counterclockwise yaw moment generated by the increased lateral force of the two front wheels actively balances the clockwise yaw moment generated by the difference in braking torque, so that the total yaw moment of the electric vehicle remains unchanged, thus preventing the electric vehicle from yawing.

[0174] In this embodiment, during the left turn of the electric vehicle on a road surface, by controlling the braking torque of one left wheel to be less than that of one right wheel, and the braking torque of the lower-tether wheel to be less than that of the higher-tether wheel, slippage of the lower-tether wheel is avoided while the braking capacity of the electric vehicle is maintained by the higher-tether wheel. Furthermore, by actively controlling the leftward turning angle of the two front wheels to increase, while considering the clockwise yaw moment generated by the difference in braking torque between the two wheels on the same axle, the counterclockwise yaw moment generated by the lateral force of the two front wheels is increased. This actively balances the clockwise yaw moment caused by the difference in braking torque, keeping the total yaw moment of the electric vehicle constant and preventing yaw.

[0175] In this embodiment of the application, taking the electric vehicle turning left on a road with two wheels facing each other as an example, the electric vehicle turning right on a road with two wheels facing each other is similar. In the driving condition, the steering angle of the two front wheels to the right is actively increased, and in the braking condition, the steering angle of the two front wheels to the right is actively decreased.

[0176] In one embodiment, the control method further includes: actively controlling the steering of the two rear wheels while the electric vehicle is traveling on a split road, such that the steering direction of the two rear wheels is different from the steering direction of the two front wheels.

[0177] That is, when the two front wheels turn left, the two rear wheels turn right, and when the two front wheels turn right, the two rear wheels turn left.

[0178] When the steering directions of the two rear wheels are different from those of the two front wheels, the yaw moment generated by the lateral forces of the two rear wheels is in the same direction as the yaw moment generated by the lateral forces of the two front wheels. This achieves the superposition of the yaw moment generated by the lateral forces of the two rear wheels on the basis of the yaw moment generated by the lateral forces of the two front wheels, and the two work together to balance the yaw moment caused by the difference between the driving torque or braking torque.

[0179] In this embodiment, during the electric vehicle's travel on a split road, the steering of the two rear wheels is actively controlled, and the steering directions of the two rear wheels are different from those of the two front wheels. This results in the yaw moment generated by the lateral force of the wheels being a superposition of the yaw moment generated by the lateral force of the two rear wheels on top of the yaw moment generated by the lateral force of the two front wheels. This achieves a synergistic balance between the two, resulting in a yaw moment caused by the difference between the driving torque or braking torque, thereby preventing the electric vehicle from yawing.

[0180] In one embodiment, the control method specifically includes: the greater the opening of the accelerator pedal, the greater the change in the steering angle of the two front wheels.

[0181] The greater the accelerator pedal opening, the stronger the driving capability required for the electric vehicle. However, the longitudinal force limit of the low-tether wheel is relatively small, requiring an increase in the driving torque output to the high-tether wheel to enhance the electric vehicle's driving capability. Thus, the greater the difference in driving torque between the two wheels on the same axle, the greater the yaw moment generated by this difference, and the more prone the electric vehicle is to yaw.

[0182] In this situation, the greater the change in the steering angle of the two front wheels by actively controlling it, the more the changing yaw moment caused by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in drive torque.

[0183] In this embodiment, a larger accelerator pedal opening indicates a stronger driving capability required from the electric vehicle. This also leads to a greater difference in the driving torque between the two coaxial wheels, resulting in a larger yaw moment and making the electric vehicle more prone to yaw. In this situation, by actively controlling the larger change in the steering angle of the two front wheels, the changing yaw moment caused by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in driving torque. This allows for flexible and active control of the change in the steering angle of the two front wheels based on the accelerator pedal opening, thereby preventing the electric vehicle from yawing under different accelerator pedal opening conditions.

[0184] In one embodiment, the control method specifically includes: the greater the opening of the brake pedal, the greater the change in the steering angle of the two front wheels.

[0185] The greater the brake pedal opening, the stronger the braking capability required for the electric vehicle. However, the longitudinal force limit of the lower-attached wheel is smaller, requiring an increase in the braking torque output to the higher-attached wheel to enhance the electric vehicle's braking capability. Consequently, the greater the difference in braking torque between the two wheels on the same axle, the greater the yaw moment generated by this difference, making the electric vehicle more prone to yaw and causing more severe yaw.

[0186] In this situation, the greater the change in the steering angle of the two front wheels by actively controlling it, the greater the change in yaw moment caused by the change in lateral force due to the change in the steering angle of the two front wheels can balance the increased yaw moment caused by the difference in braking torque.

[0187] In this embodiment, a larger brake pedal opening indicates a stronger braking capability required from the electric vehicle. This also leads to a greater difference in braking torque between the two wheels on the same axle, resulting in a larger yaw moment and making the electric vehicle more prone to yaw. In this situation, by actively controlling the larger change in the steering angle of the two front wheels, the changing yaw moment caused by the change in lateral force of the two front wheels can balance the increased yaw moment caused by the difference in braking torque. This allows for flexible and active control of the change in the steering angle of the two front wheels based on the brake pedal opening, thereby preventing the electric vehicle from yawing under different accelerator pedal openings.

[0188] In one embodiment, the control method specifically includes: the greater the rate of increase or decrease of the difference between the driving torque or braking torque of a left wheel and a right wheel, the greater the rate of change of the steering angle of the two front wheels actively controlled.

[0189] That is, the changes in the steering angle of the two front wheels and the changes in the difference between the driving torque or braking torque of the left wheel and the right wheel are synchronized, which can avoid the yaw moment caused by the output of the braking torque or driving torque of the two wheels on the same axle, which would cause the electric vehicle to yaw.

[0190] For ease of understanding, see Figure 6 and Figure 7 At the moment t1 after the electric vehicle enters the split road surface, the difference in driving torque between the left and right wheels and the steering angle of the two front wheels simultaneously increase to a certain value and then remain constant. The change in braking torque can be further explained in [reference needed]. Figure 7 .

[0191] In this embodiment, before the electric vehicle enters the split road surface, the greater the rate of increase or decrease of the difference between the driving torque or braking torque of one left wheel and one right wheel, the greater the rate of change of the steering angle of the two front wheels, so that the change of the steering angle of the two front wheels and the change of the difference between the driving torque or braking torque of one left wheel and one right wheel are synchronized. That is, the changing yaw moment generated by the change of the lateral force of the two front wheels can balance the yaw moment generated by the difference between the braking torque or driving torque, thereby preventing the electric vehicle from yawing.

[0192] In one embodiment, the control method specifically includes: the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the change in the steering angle of the two front wheels is actively controlled.

[0193] The greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference in the driving torque or braking torque of the two wheels on the same axle, and the greater the yaw moment generated by this difference.

[0194] In this situation, the greater the change in the steering angle of the two front wheels by actively controlling it, the more the changing yaw moment caused by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in braking torque.

[0195] In this embodiment, the greater the difference between the coefficient of adhesion between a left wheel and the road surface and the coefficient of adhesion between a right wheel and the road surface, the greater the difference in driving torque or braking torque between the two wheels on the same axle, and the greater the yaw moment generated by this difference. In this case, by actively controlling the change in the steering angle of the two front wheels, the changing yaw moment generated by the change in the lateral force of the two front wheels can balance the increased yaw moment caused by the difference in braking torque. This allows for flexible control of the change in the steering angle of the two front wheels based on the difference in the coefficient of adhesion between the two wheels on the same axle and the road surface, thereby preventing the electric vehicle from yawing under different differences in coefficient of adhesion.

[0196] This application provides a controller for an electric vehicle 100, which is used to execute the electric vehicle control method provided in the above embodiment.

[0197] The controller is used to: control the steering angle of the two front wheels of the electric vehicle to change with the steering wheel angle before the electric vehicle enters the split road surface; after the electric vehicle enters the split road surface and before it leaves the split road surface, control the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle to increase, and actively control the steering angle of the two front wheels to increase or decrease; wherein, during the electric vehicle's travel on the split road surface, the difference between the adhesion coefficient between one left wheel and the road surface and the adhesion coefficient between one right wheel and the road surface is greater than a preset value.

[0198] See Figure 11 , Figure 11 A schematic diagram of a controller provided in an embodiment of this application is shown.

[0199] like Figure 11 As shown, the controller receives pedal signals and steering wheel signals. Before the electric vehicle enters the split road, it controls the steering of the two front wheels of the electric vehicle according to the steering wheel signal and controls the output torque of the drive system or braking system according to the pedal signal. After the electric vehicle enters the split road and before it leaves the split road, it controls the drive system or braking system to adjust the torque output to one left wheel and one right wheel on the same axle, and actively controls the front wheel steering system to adjust the turning angle of the two front wheels.

[0200] Among them, the steering wheel signal indicates the direction and angle of steering wheel rotation, and the pedal signal indicates the opening degree of the brake pedal and the accelerator pedal.

[0201] In one embodiment, the controller can also actively control the rear-wheel steering system to adjust the steering angle of the two rear wheels.

[0202] In one embodiment, the controller may be a central controller.

[0203] In another embodiment, the controller can be a controller used for controlling the electric vehicle's operation on split-level roads. The two can serve as backups for each other, improving the control stability of the electric vehicle.

[0204] See Figure 12 , Figure 12 A schematic diagram of the operating logic of a controller provided in an embodiment of this application is shown.

[0205] In the controller, the chassis control module receives the pedal signal and calculates the torque to be output to each wheel based on the pedal signal. After the electric vehicle enters the split road, the four-wheel torque coordination control module adjusts the drive system or braking system to output torque to each wheel. At the same time, the steering wheel angle control module outputs the torque difference between the two wheels on the same axle, and the steering system is controlled by the steering wheel angle control module.

[0206] During this process, the steering wheel angle control module can also control the steering system based on path deviation and heading deviation.

[0207] In another embodiment of this application, an electric vehicle is also provided, the electric vehicle including a controller and four wheels, wherein: The controller is used to: control the steering angle of the two front wheels of the electric vehicle to change with the steering wheel angle before the electric vehicle enters the split road surface; after the electric vehicle enters the split road surface and before it leaves the split road surface, control the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle to increase, and actively control the steering angle of the two front wheels to increase or decrease; wherein, during the electric vehicle's travel on the split road surface, the difference between the adhesion coefficient between one left wheel and the road surface and the adhesion coefficient between one right wheel and the road surface is greater than a preset value.

[0208] It is understood that all relevant content of each step involved in the above method embodiments can be referenced in the embodiments of the controller and the embodiments of the electric vehicle, and will not be repeated here.

[0209] Finally, it should be noted that the above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A control method for an electric vehicle, characterized in that, The control method is used to prevent the electric vehicle from yawing by controlling the coordination of the steering system and the drive system or braking system during the driving of the electric vehicle on a split road surface. The control method includes: Before the electric vehicle enters the split road surface, the steering angle of the two front wheels of the electric vehicle is controlled to change with the steering wheel angle. After the electric vehicle enters the split road surface and before it leaves the split road surface, the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle is increased, and the steering angle of the two front wheels is actively increased or decreased. Wherein, during the process of the electric vehicle traveling on the split road, the difference between the adhesion coefficient between the left wheel and the road surface and the adhesion coefficient between the right wheel and the road surface is greater than a preset value.

2. The control method according to claim 1, characterized in that, The control method specifically includes: After the electric vehicle enters the split road surface and before it leaves the split road surface, the difference between the driving torque or braking torque of the left wheel and the right wheel is increased, and the steering angle of the two front wheels is actively increased or decreased before the steering wheel angle changes.

3. The control method according to claim 1, characterized in that, The control method specifically includes: Before increasing the difference between the driving torque or braking torque of the left wheel and the right wheel, the difference between the driving torque or braking torque of the left wheel and the right wheel is first controlled to decrease.

4. The control method according to claim 1, characterized in that, The control method specifically includes: Before increasing the difference between the driving torque or braking torque of the left wheel and the right wheel, the driving torque or braking torque of the left wheel and the right wheel are simultaneously decreased.

5. The control method according to claim 4, characterized in that, The control method specifically includes: The duration during which the driving torque or braking torque of one left wheel and one right wheel decreases simultaneously is less than the duration during which the difference between the driving torque or braking torque of one left wheel and one right wheel increases.

6. The control method according to claim 1, characterized in that, The control method further includes: After the electric vehicle leaves the split road surface, the difference between the driving torque or braking torque between one left wheel and one right wheel on the same axle is reduced, and the steering angle of the two front wheels is actively controlled to decrease or increase.

7. The control method according to claim 1, characterized in that, The control method specifically includes: During the process of the electric vehicle traveling in a straight line on the split road, the coefficient of adhesion between the left wheel and the road surface is less than that between the right wheel and the road surface. When the opening of the accelerator pedal is greater than the preset accelerator pedal opening, the driving torque of the left wheel is controlled to be less than that of the right wheel, and the two front wheels are actively controlled to turn to the right.

8. The control method according to claim 1, characterized in that, The control method specifically includes: During the process of the electric vehicle traveling in a straight line on the split road, the coefficient of adhesion between the left wheel and the road surface is less than that between the right wheel and the road surface. When the opening of the brake pedal is greater than the preset brake pedal opening, the braking torque of the left wheel is controlled to be less than that of the right wheel, and the two front wheels are actively controlled to turn to the left.

9. The control method according to claim 1, characterized in that, The control method specifically includes: During the process of the electric vehicle turning left on the road surface, the coefficient of adhesion between the left wheel and the road surface is less than the coefficient of adhesion between the right wheel and the road surface. When the opening of the accelerator pedal is greater than the preset accelerator pedal opening, the difference in driving torque between the left wheel and the coaxial right wheel is increased, and the leftward turning angle of the two front wheels is actively reduced.

10. The control method according to claim 1, characterized in that, The control method specifically includes: During the process of the electric vehicle turning left on the opposite road surface, the coefficient of adhesion between the left wheel and the road surface is less than the coefficient of adhesion between the right wheel and the road surface. When the opening of the brake pedal is greater than the preset brake pedal opening, the difference in braking torque between the left wheel and the right wheel on the same axle is increased, and the leftward turning angle of the two front wheels is actively increased.

11. The control method according to any one of claims 7-10, characterized in that, The control method further includes: During the electric vehicle's operation on the split road surface, the two rear wheels are actively steered, and the steering direction of the two rear wheels is different from that of the two front wheels.

12. The control method according to claim 1 or 6, characterized in that, The control method specifically includes: The greater the rate of increase or decrease of the difference between the driving torque or braking torque of the left wheel and the right wheel, the greater the rate of change of the steering angle of the two front wheels actively controlled.

13. The control method according to claim 1, characterized in that, The control method specifically includes: The greater the difference between the coefficient of adhesion between the left wheel and the road surface and the coefficient of adhesion between the right wheel and the road surface, the greater the change in the steering angle of the two front wheels can be actively controlled.

14. A controller, characterized in that, The controller is used for: Before the electric vehicle enters the split road surface, the steering angle of the two front wheels of the electric vehicle is controlled to change with the steering wheel angle. After the electric vehicle enters the split road surface and before it leaves the split road surface, the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle is increased, and the steering angle of the two front wheels is actively increased or decreased. Wherein, during the process of the electric vehicle traveling on the split road, the difference between the adhesion coefficient between the left wheel and the road surface and the adhesion coefficient between the right wheel and the road surface is greater than a preset value.

15. An electric vehicle, characterized in that, The electric vehicle includes a controller and four wheels, wherein: The controller is used for: Before the electric vehicle enters the split road surface, the steering angle of the two front wheels of the electric vehicle is controlled to change with the steering wheel angle. After the electric vehicle enters the split road surface and before it leaves the split road surface, the difference between the driving torque or braking torque of one left wheel and one right wheel on the same axle is increased, and the steering angle of the two front wheels is actively increased or decreased. Wherein, during the process of the electric vehicle traveling on the split road, the difference between the adhesion coefficient between the left wheel and the road surface and the adhesion coefficient between the right wheel and the road surface is greater than a preset value.

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