Slip rate control method, device and equipment and vehicle

Abstract

The invention discloses a slip rate control method and device, electronic equipment and a vehicle. The method comprises the following steps: identifying the pavement state of each wheel according to the slip rate of each wheel; acquiring a reference slip rate according to the vehicle mode, the vehicle speed and the steering characteristics; the target slip rate of each wheel is set based on the reference slip rate, the vehicle speed and the road surface state of each wheel; obtaining a single-wheel target wheel speed of each wheel according to the target slip rate of each wheel; obtaining the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel; judging the activation or quit of the slip rate control of each wheel by using the single-wheel speed difference; and when any wheel slip rate control is activated, the vehicle control unit VCU is used for adjusting the torque of the wheel, so that the slip rate of the wheel reaches the corresponding target slip rate. The target slip rate is set according to the actual condition when the vehicle runs, the wheels reach the target slip rate through the VCU, and the four-wheel independent drive vehicle can be well controlled.

Description

Technical Field

[0001] This application relates to the field of vehicle control, and particularly to a slip ratio control method, device, equipment and vehicle. Background Art

[0002] Traditional four-wheel drive vehicles are controlled by two driving devices for the front axle and the rear axle respectively, that is, one driving device controls the two tires of the front axle and the other driving device controls the two tires of the rear axle. With the development of new energy technology, in order to control the vehicle more precisely, major enterprises have developed vehicles with four-wheel independent drive. The four motors of the four-wheel independent drive vehicle are all independently controllable, which is beneficial to improving the power performance and stability on uniform low-adhesion and crosswise roads, as well as the off-road performance on muddy roads. However, with the increase in control freedom, the control difficulty also increases. Therefore, it is necessary to perform single-wheel slip ratio control on four-wheel independent drive vehicles to avoid vehicle deviation.

[0003] Therefore, how to better control four-wheel independent drive vehicles has become a technical problem that needs to be solved urgently in this field. Summary of the Invention

[0004] Based on the above problems, this application provides a slip ratio control method, device, equipment and vehicle, which can better control four-wheel independent drive vehicles.

[0005] The embodiments of this application disclose the following technical solutions:

[0006] In a first aspect, an embodiment of this application provides a slip ratio control method for controlling a four-wheel independent drive vehicle. The method includes:

[0007] Identify the road surface state where each wheel is located according to the slip ratio of each wheel;

[0008] Obtain a reference slip ratio according to the vehicle mode, vehicle speed and steering characteristics;

[0009] Set the target slip ratio of each wheel based on the reference slip ratio, the vehicle speed and the road surface state where each wheel is located;

[0010] Obtain the single-wheel target wheel speed of each wheel according to the target slip ratio of each wheel;

[0011] Obtain the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel;

[0012] Use the single-wheel speed difference to judge the activation or deactivation of the slip ratio control of each wheel;

[0013] When the slip ratio control of any wheel is activated, use the vehicle control unit VCU to adjust the torque of the wheel so that the slip ratio of the wheel reaches the corresponding target slip ratio.

[0014] Optionally, identifying the road surface condition where each wheel is located according to the slip ratio of each wheel includes:

[0015] When the slip ratio of a wheel is greater than or equal to a preset slip ratio threshold, identifying the road surface condition where the wheel is located as a low-adhesion road surface;

[0016] When the slip ratio of a wheel is less than the preset slip ratio threshold, identifying the road surface condition where the wheel is located as a high-adhesion road surface;

[0017] When the tires on both sides of the front axle are respectively on a low-adhesion road surface and a high-adhesion road surface, identifying the road surface condition where the front axle is located as a split road surface;

[0018] When the tires on both sides of the rear axle are respectively on a low-adhesion road surface and a high-adhesion road surface, identifying the road surface condition where the rear axle is located as a split road surface.

[0019] Optionally, when the vehicle is on a split road surface, the method further includes:

[0020] When the vehicle is in a driving state, reducing the torque of the four wheels to the same value;

[0021] When the vehicle is in a braking state, increasing the torque of the four wheels to the same value

[0022] After a preset time delay, gradually increasing the torque of the wheel on the high-adhesion road surface side.

[0023] Optionally, setting the target slip ratio of each wheel based on the reference slip ratio, the vehicle speed, and the road surface condition where each wheel is located includes:

[0024] When the vehicle speed is lower than a preset vehicle speed threshold, increasing the slip ratio setting value on the basis of the reference slip ratio to obtain the target slip ratio;

[0025] When the vehicle speed is greater than or equal to the preset vehicle speed threshold, reducing the slip ratio setting value on the basis of the reference slip ratio to obtain the target slip ratio;

[0026] When oversteering, increasing the slip ratio setting values of the two wheels on the front axle on the basis of the reference slip ratio to obtain the target slip ratios of the two wheels on the front axle;

[0027] When understeering, increasing the slip ratio setting values of the two wheels on the rear axle on the basis of the reference slip ratio to obtain the target slip ratios of the two wheels on the rear axle;

[0028] When the left rear wheel is about to enter a high-adhesion road surface, increasing the slip ratio setting value of the left rear wheel on the basis of the reference slip ratio to obtain the target slip ratio of the left rear wheel;

[0029] When the right rear wheel is about to enter the high - adhesion road surface, increase the set value of the slip ratio of the right rear wheel on the basis of the reference slip ratio to obtain the target slip ratio of the right rear wheel;

[0030] When the left front wheel is about to enter the high - adhesion road surface, increase the set value of the slip ratio of the left front wheel on the basis of the reference slip ratio to obtain the target slip ratio of the left front wheel;

[0031] When the right front wheel is about to enter the high - adhesion road surface, increase the set value of the slip ratio of the right front wheel on the basis of the reference slip ratio to obtain the target slip ratio of the right front wheel;

[0032] Periodically increase the single - wheel target slip ratio.

[0033] Optionally, the obtaining of the single - wheel target wheel speed of each wheel according to the target slip ratio of each wheel includes:

[0034] In the driving state, the single - wheel target wheel speed is the ratio of the vehicle speed to the difference between 1 and the target slip ratio;

[0035] In the braking state, the single - wheel target wheel speed is the product of the vehicle speed and the difference between 1 and the target slip ratio.

[0036] Optionally, the using the vehicle control unit (VCU) to change the torque of the wheel includes:

[0037] Use the vehicle control unit (VCU) to control the torque of the wheel by the difference between the feed - forward control torque and the feedback control torque.

[0038] Optionally, the feed - forward control torque is the difference between the actual torque of the motor and the inertia torque of rotation; the feedback control torque is obtained by performing a PID closed - loop control on the difference in wheel speed change rate; the difference in wheel speed change rate is the difference between the actual wheel speed change rate and the target wheel speed change rate.

[0039] In a second aspect, an embodiment of the present application provides a slip - ratio control device for controlling a vehicle with four - wheel independent drive. The device includes:

[0040] A road - surface state recognition module, configured to recognize the road - surface state where each wheel is located according to the slip ratio of each wheel;

[0041] A reference slip - ratio obtaining module, configured to obtain a reference slip ratio according to the vehicle mode, vehicle speed, and steering characteristics;

[0042] A target slip - ratio setting module, configured to set the target slip ratio of each wheel based on the reference slip ratio, the vehicle speed, and the road - surface state where each wheel is located;

[0043] A single - wheel target vehicle - speed obtaining module, configured to obtain the single - wheel target wheel speed of each wheel according to the target slip ratio of each wheel;

[0044] A single-wheel speed difference acquisition module, configured to acquire the single-wheel speed difference of each wheel according to the single-wheel target speed of each wheel.

[0045] A slip ratio control activation or deactivation module, configured to determine the activation or deactivation of the slip ratio control of each wheel by using the single-wheel speed difference.

[0046] A torque adjustment module, configured to adjust the torque of a wheel by using a vehicle control unit (VCU) when the slip ratio control of any wheel is activated, so that the slip ratio of the wheel reaches the corresponding target slip ratio.

[0047] In a third aspect, an embodiment of the present application provides an electronic device, including:

[0048] A memory, configured to store a computer program;

[0049] A processor, configured to implement the steps of the above-mentioned slip ratio control method when executing the computer program.

[0050] In a fourth aspect, an embodiment of the present application provides a vehicle, characterized by including the above-mentioned memory and processor.

[0051] Compared with the prior art, the present application has the following beneficial effects:

[0052] A slip ratio control method provided by an embodiment of the present application is used to control a vehicle with four-wheel independent drive. The road surface state where each wheel is located is identified according to the slip ratio of each wheel; a reference slip ratio is obtained according to the vehicle mode, vehicle speed, and steering characteristics; the target slip ratio of each wheel is set based on the reference slip ratio, the vehicle speed, and the road surface state where each wheel is located; the single-wheel target speed of each wheel is obtained according to the target slip ratio of each wheel; the single-wheel speed difference of each wheel is obtained according to the single-wheel target speed of each wheel; the activation or deactivation of the slip ratio control of each wheel is determined by using the single-wheel speed difference; when the slip ratio control of any wheel is activated, the torque of the wheel is adjusted by using a vehicle control unit (VCU) so that the slip ratio of the wheel reaches the corresponding target slip ratio. The target slip ratio is set according to the actual situation during vehicle driving, and the torque of each wheel is controlled by the VCU to make each wheel reach the target slip ratio, which can enable the vehicle to make full use of adhesion, enhance the grip force, and achieve continuous and stable acceleration or deceleration under working conditions such as uniform low adhesion, oncoming roads, and muddy roads, and at the same time can effectively avoid vehicle deviation. Therefore, a slip ratio control method provided by an embodiment of the present application can better control a vehicle with four-wheel independent drive.

[0053] It should be noted that a slip ratio control device, an electronic device, and a vehicle provided by the present application also have the above-mentioned beneficial effects because they can implement the steps of the above-mentioned slip ratio control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0055] Figure 1 It is a schematic flowchart of a slip ratio control method provided by an embodiment of the present application;

[0056] Figure 2 It is a schematic diagram of a split road surface provided by an embodiment of the present application;

[0057] Figure 3 It is a schematic structural diagram of a slip ratio control device provided by an embodiment of the present application;

[0058] Figure 4 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0059] As described above, currently, in order to more precisely control vehicles, major enterprises have developed vehicles with four-wheel independent drive. The four motors of the four-wheel independent drive vehicle are all independently controllable, which is beneficial to improving the power performance and stability on uniform low-adhesion and split road surfaces, as well as the off-road performance on muddy road surfaces. However, with the increase in the degree of control freedom, the control difficulty also increases accordingly. Therefore, it is necessary to perform single-wheel slip ratio control on the four-wheel independent drive vehicle to avoid vehicle deviation.

[0060] Through research, the inventor has invented a slip ratio control method, device, equipment and vehicle, which can better control the four-wheel independent drive vehicle.

[0061] In order to enable those skilled in the art to better understand the solutions of the present application, the following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application.

[0062] Method Embodiment

[0063] See Figure 1 , which is a schematic flowchart of a slip ratio control method provided by an embodiment of the present application, including the following steps:

[0064] S101. Identify the road surface conditions where each wheel is located based on the slip ratio of each wheel.

[0065] It should be noted that the slip ratio control method provided in the embodiments of this application is applicable to controlling a vehicle with four-wheel independent drive, specifically a four-wheel independent drive vehicle equipped with four in-wheel motors or four wheel hub motors.

[0066] During the actual driving process of the vehicle, since the road surface conditions of the four tires are usually not exactly the same, it is necessary to identify the road surface conditions where each wheel is located. Specifically, the road surface conditions where each wheel is located can be identified through the slip ratio of each wheel.

[0067] In the embodiments provided in this application, the road surface conditions can be divided into low-adhesion road surfaces and high-adhesion road surfaces; when the slip ratio of a wheel is greater than or equal to the preset slip ratio threshold, the road surface condition where the wheel is located can be identified as a low-adhesion road surface; when the slip ratio of a wheel is less than the preset slip ratio threshold, the road surface condition where the wheel is located can be identified as a high-adhesion road surface. It should be noted that the preset slip ratio threshold can be set by each enterprise according to the actual situation. For example, usually, the preset slip ratio threshold can be set to 15%, that is, when the slip ratio of a wheel is greater than or equal to 15%, the road surface condition where the wheel is located is identified as a low-adhesion road surface, and when the slip ratio of a wheel is less than 15%, the road surface condition where the wheel is located is identified as a high-adhesion road surface; however, due to different enterprise standards, the setting of the preset slip ratio threshold may be adaptively adjusted based on this value of 15%.

[0068] It should be noted that for the situation where the tires on both sides of the front axle are respectively on a low-adhesion road surface and a high-adhesion road surface, the road surface condition where the front axle is located can be identified as a split road surface; for the situation where the tires on both sides of the rear axle are respectively on a low-adhesion road surface and a high-adhesion road surface, the road surface condition where the rear axle is located can be identified as a split road surface. Specifically, for the split road surface, reference can be made to Figure 2 This figure is a schematic diagram of a split road surface provided in the embodiments of this application. Among them, the part on the 21 side is a low-adhesion road surface, and the part on the 22 side is a high-adhesion road surface. At this time, both the front axle and the rear axle are in a split road surface. Figure 2 The road surface with different ground adhesion on both sides as shown is the split road surface.

[0069] Specifically, when the vehicle is on a split road surface, the torque of the four wheels can be coordinately controlled. For the driving scenario and the braking scenario, the ways of coordinately controlling the torque of the four wheels are different.

[0070] In the driving scenario, first reduce the torques of all four wheels to the same value, which can avoid generating unexpected yaw moments. After a time delay of a preset time, gradually increase the torque of the wheels on the side with high adhesion road surface. It should be noted that the preset time can be set according to the actual situation. The purpose of setting the time delay of the preset time is to allow the driver sufficient time to adjust the steering wheel to keep the vehicle driving straight. For example, if the torques of the four wheels are 90 N·m, 100 N·m, 110 N·m, and 120 N·m respectively, first reduce the torques of all four wheels to 80 N·m. After 2 s, increase the torque of the wheels on the high adhesion road surface at a certain gradient, so that the wheels on the high adhesion side gradually exert greater driving ability and improve the driving acceleration ability under split - friction road surfaces.

[0071] In the braking scenario, first increase the torques of all four wheels to the same value, which can also avoid generating unexpected yaw moments. After a time delay of a preset time, gradually increase the torque of the wheels on the side with high adhesion road surface. For example, if the torques of the four wheels are 90 N·m, 100 N·m, 110 N·m, and 120 N·m respectively, first increase the torques of all four wheels to 130 N·m. After 2 s, increase the torque of the wheels on the high adhesion road surface at a certain gradient, so that the wheels on the high adhesion side gradually exert greater braking ability and improve the electric braking deceleration performance under split - friction road surfaces.

[0072] S102. Obtain the reference slip ratio according to the vehicle mode, vehicle speed, and steering characteristics.

[0073] It should be noted that the vehicle mode is the driving mode of the vehicle, such as standard mode, sport mode, snow mode, mud mode, etc.; the vehicle speed is the actual vehicle speed; the steering characteristics can be represented by the difference between the actual yaw angular velocity and the desired yaw angular velocity.

[0074] Specifically, different MAP tables can be preset for different vehicle modes. Two dimensions are set in the MAP table: vehicle speed and steering characteristics. In each vehicle mode, there is a unique corresponding reference slip ratio for different vehicle speeds and steering characteristics. Therefore, in step S102, different MAP tables can be queried according to different vehicle modes, and the corresponding reference slip ratio can be found using the vehicle speed and steering characteristics in the corresponding MAP table.

[0075] It should be noted that the reference slip ratios corresponding to the same vehicle speed and steering characteristics are different in different MAP tables, that is, the reference slip ratios corresponding to the same vehicle speed and steering characteristics are different in different vehicle modes. For example, the slip ratio corresponding to vehicle speed a and steering characteristic b in the standard mode is 15%. In the sport mode, since power is prioritized in the sport mode, the slip ratio can be appropriately increased. The slip ratio corresponding to vehicle speed a and steering characteristic b can be set to 20% to provide as much power as possible. In the snow mode, the slip ratio can be appropriately decreased. The slip ratio corresponding to vehicle speed a and steering characteristic b can be set to 10% to avoid skidding as much as possible.

[0076] S103. Set the target slip ratios of the respective wheels based on the reference slip ratio, the vehicle speed, and the road surface conditions of the respective wheels.

[0077] Specifically, when the vehicle speed is lower than the preset vehicle speed threshold, increase the slip ratio setting value based on the reference slip ratio to obtain the target slip ratio; when the vehicle speed is greater than or equal to the preset vehicle speed threshold, decrease the slip ratio setting value based on the reference slip ratio to obtain the target slip ratio. It should be noted that the preset vehicle speed threshold can be set according to the actual situation. When the vehicle speed is lower than the preset vehicle speed threshold, it can be considered that the vehicle is in a low-speed running state at this time. Then, to provide sufficient power, the target slip ratio can be appropriately increased. When the vehicle speed is greater than or equal to the preset vehicle speed threshold, it can be considered that the vehicle is in a high-speed running state at this time. To maintain the stability of the vehicle, the target slip ratio can be appropriately decreased.

[0078] When oversteering, increase the slip ratio setting values of the two wheels on the front axle based on the reference slip ratio to obtain the target slip ratio; when understeering, increase the slip ratio setting values of the two wheels on the rear axle based on the reference slip ratio to obtain the target slip ratios of the two wheels on the rear axle. When oversteering, appropriately relaxing the target slip ratio of the front axle can enable the front axle to respond to more torque to increase the lateral force of the rear axle; when understeering, appropriately relaxing the target slip ratio of the rear axle can enable the rear axle to respond to more torque to increase the lateral force of the front axle. It should be noted that the determination of oversteering or understeering can be achieved by setting a preset steering angle value. When the steering angle is greater than or equal to the preset steering angle value, it can be considered that oversteering occurs at this time; when the steering angle is less than the preset steering angle value, it can be considered that understeering occurs at this time.

[0079] When the left rear wheel is about to enter the high - adhesion road surface, increase the set value of the slip rate of the left rear wheel on the basis of the reference slip rate to obtain the target slip rate of the left rear wheel; when the right rear wheel is about to enter the high - adhesion road surface, increase the set value of the slip rate of the right rear wheel on the basis of the reference slip rate to obtain the target slip rate of the right rear wheel; when the left front wheel is about to enter the high - adhesion road surface, increase the set value of the slip rate of the left front wheel on the basis of the reference slip rate to obtain the target slip rate of the left front wheel; when the right front wheel is about to enter the high - adhesion road surface, increase the set value of the slip rate of the right front wheel on the basis of the reference slip rate to obtain the target slip rate of the right front wheel. In the embodiment provided by the present application, the judgment of "about to enter the high - adhesion road surface" can be achieved in the following ways:

[0080] When the vehicle is in D - gear, the left front wheel has just entered the high - adhesion road surface and the left rear wheel is on the low - adhesion road surface, it can be considered that the left rear wheel will also enter the high - adhesion road surface after a certain period of time; when the vehicle is in D - gear, the right front wheel has just entered the high - adhesion road surface and the right rear wheel is on the low - adhesion road surface, it can be considered that the right rear wheel will also enter the high - adhesion road surface after a certain period of time; when the vehicle is in R - gear, the left rear wheel has just entered the high - adhesion road surface and the left front wheel is on the low - adhesion road surface, it can be considered that the left front wheel will also enter the high - adhesion road surface after a certain period of time; when the vehicle is in R - gear, the right rear wheel has just entered the high - adhesion road surface and the right front wheel is on the low - adhesion road surface, it can be considered that the right front wheel will also enter the high - adhesion road surface after a certain period of time.

[0081] It should be noted that when it is judged that the left rear wheel is about to enter the high - adhesion road surface, increasing its target slip rate can smoothly and more quickly exit the slip - rate control and respond to the driver's required torque. For example, in the driving scenario, increasing the target slip rate will increase the target wheel speed, and the single - wheel speed difference is negative, which can achieve the effect of increasing torque and more quickly exit the drive - slip control; while in the braking scenario, increasing the target slip rate will decrease the target wheel speed, and the single - wheel speed difference is positive, which can achieve the effect of decreasing torque and more quickly exit the electric - braking anti - lock control. The control principles for the other three wheels are similar and will not be elaborated here.

[0082] In the embodiment provided by the present application, as an example, the target slip rate of each wheel can also be increased periodically. Periodically and tentatively increasing the single - wheel target slip rate can detect the slipping or locking boundary of the wheel to enhance the dynamic performance on the low - adhesion road surface.

[0083] S104, obtain the single - wheel target wheel speed of each wheel according to the target slip rate of each wheel.

[0084] Specifically, when driving wheel slip occurs and when braking lock occurs, the method of obtaining the single-wheel target wheel speed of each wheel based on the target slip ratio of each wheel is different. When driving wheel slip occurs, since the slip ratio is the ratio of the difference between the wheel speed and the vehicle speed to the wheel speed, the single-wheel target wheel speed is the ratio of the vehicle speed to the difference between 1 and the single-wheel target slip ratio; when braking lock occurs, since the slip ratio is the ratio of the difference between the vehicle speed and the wheel speed to the vehicle speed, the single-wheel target wheel speed is the product of the vehicle speed and the difference between 1 and the single-wheel target slip ratio.

[0085] S105. Obtain the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel.

[0086] Specifically, the single-wheel actual wheel speed can be obtained first. The single-wheel actual wheel speed is the corresponding motor speed (rpm) of the wheel / gear ratio * (rpm2radps) * tire radius; then, the single-wheel speed difference is obtained according to the difference between the single-wheel actual wheel speed and the single-wheel target wheel speed, that is, the single-wheel speed difference = single-wheel actual wheel speed - single-wheel target wheel speed.

[0087] S106. Use the single-wheel speed difference to judge the activation or deactivation of the slip ratio control of each wheel.

[0088] In the embodiments provided in the present application, there are different judgment methods for the activation or deactivation of the slip ratio control of each wheel in different situations. For example, when the single-wheel speed difference exceeds the preset single-wheel speed difference value, the slip ratio control of the wheel is activated, and the preset single-wheel speed difference value can be set according to the actual situation; it is also possible to activate the slip ratio control of the wheel in advance when it is judged that a certain wheel is about to enter a low-adhesion road surface and the vehicle speed is relatively high to prevent the vehicle from slipping or locking; for the driving scenario, when the single-wheel actual wheel speed drops to the corresponding target wheel speed, and the absolute value of the difference between the driver's required torque for the wheel and the target torque of the wheel's slip ratio control is less than the preset value, the slip ratio control of the wheel is deactivated; for the braking scenario, when the single-wheel actual wheel speed rises to the corresponding target wheel speed, and the absolute value of the difference between the driver's required torque for the wheel and the target torque of the wheel's slip ratio control is less than the preset value, the slip ratio control of the wheel is deactivated.

[0089] S107. When the slip ratio control of any wheel is activated, use the vehicle controller VCU to adjust the torque of the wheel so that the slip ratio of the wheel reaches the corresponding target slip ratio.

[0090] It should be noted that the vehicle controller (Vehicle Controller Unit, VCU) is the core control component of the vehicle. It can collect the accelerator pedal signal, brake pedal signal and other component signals, and after making corresponding judgments, control the actions of the lower-level component controllers to drive the vehicle to run normally.

[0091] Specifically, the vehicle controller VCU can be used to control the torque of the wheel by using the difference between the feedforward control torque and the feedback control torque. When the single-wheel slip rate control is activated, the VCU can control the wheel to switch from the current required torque to the target torque corresponding to the target slip rate of the wheel, so that the wheel can be controlled to the target slip rate to obtain maximum adhesion and enhance the vehicle's power and handling stability on low-adhesion roads. In the driving scenario, the target torque is less than the driver's required torque, which can achieve torque reduction and improve wheel slip; for the braking scenario, the target torque is greater than the driver's required torque, which can achieve torque increase and improve wheel locking.

[0092] Among them, the feedforward control torque is the difference between the actual torque of the motor and the rotational inertia torque; and the feedback control torque is obtained by PID closed-loop control of the wheel speed change rate difference, and the wheel speed change rate difference is the difference between the actual wheel speed change rate and the target wheel speed change rate. It should be noted that the feedback control is acceleration closed-loop control, that is, the target wheel speed change rate is obtained by looking up the table according to the single wheel speed difference. The use of acceleration closed-loop control can achieve smoother speed control and avoid the situation where the torque is reduced or increased too quickly, causing the vehicle to shake.

[0093] In the embodiment provided in the present application, a special four-wheel torque coordination control scheme is also provided for escape scenarios: when it is determined that a wheel is about to enter a low-adhesion road surface and the vehicle speed is low, not only does it not enter the slip rate control in advance, but the torque is compensated to the other axle. For driving scenarios, if the front wheels enter a low-adhesion road surface, the front wheel driving force will suddenly weaken, and the weakened part of the driving torque can be compensated to the rear axle, which is conducive to enhancing the vehicle's escape ability. For electric braking scenarios, if the front wheels enter a low-adhesion road surface, the front wheel electric braking force will suddenly weaken, and the weakened part of the electric braking torque can be compensated to the rear axle, which is conducive to improving the feeling of under-braking.

[0094] A slip ratio control method provided by the present application is used to control a vehicle with four-wheel independent drive. The road surface state where each wheel is located is identified according to the slip ratio of each wheel; a reference slip ratio is obtained according to the vehicle mode, vehicle speed, and steering characteristics; the target slip ratio of each wheel is set based on the reference slip ratio, the vehicle speed, and the road surface state where each wheel is located; the single-wheel target wheel speed of each wheel is obtained according to the target slip ratio of each wheel; the single-wheel speed difference of each wheel is obtained according to the single-wheel target wheel speed of each wheel; the activation or deactivation of the slip ratio control of each wheel is judged by using the single-wheel speed difference; when the slip ratio control of any wheel is activated, the vehicle control unit (VCU) is used to adjust the torque of the wheel so that the slip ratio of the wheel reaches the corresponding target slip ratio. Setting the target slip ratio according to the actual situation during vehicle driving and controlling the torque of each wheel through the VCU to make each wheel reach the target slip ratio can enable the vehicle to make full use of adhesion, enhance the grip, achieve continuous and stable acceleration or deceleration under working conditions such as uniform low adhesion, split road surface, and muddy road surface, and at the same time can effectively avoid vehicle deviation. Therefore, a slip ratio control method provided by the embodiments of the present application can better control a vehicle with four-wheel independent drive.

[0095] Device Embodiment

[0096] See Figure 3 , which is a schematic structural diagram of a slip ratio control device provided by an embodiment of the present application, including: a road surface state recognition module 301, a reference slip ratio acquisition module 302, a target slip ratio setting module 303, a single-wheel target vehicle speed acquisition module 304, a single-wheel speed difference acquisition module 305, a slip ratio control activation or deactivation module 306, and a torque adjustment module 307.

[0097] Among them, the road surface state recognition module 301 is used to identify the road surface state where each wheel is located according to the slip ratio of each wheel;

[0098] The reference slip ratio acquisition module 302 is used to obtain the reference slip ratio according to the vehicle mode, vehicle speed, and steering characteristics;

[0099] The target slip ratio setting module 303 is used to set the target slip ratio of each wheel based on the reference slip ratio, the vehicle speed, and the road surface state where each wheel is located;

[0100] The single-wheel target vehicle speed acquisition module 304 is used to obtain the single-wheel target wheel speed of each wheel according to the target slip ratio of each wheel;

[0101] The single-wheel speed difference acquisition module 305 is used to obtain the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel;

[0102] The slip ratio control activation or deactivation module 306 is used to determine the activation or deactivation of the slip ratio control for each wheel by using the single-wheel speed difference;

[0103] The torque adjustment module 307 is used to adjust the torque of the wheel by using the vehicle control unit VCU when the slip ratio control of any wheel is activated, so that the slip ratio of the wheel reaches the corresponding target slip ratio.

[0104] Optionally, the road surface condition recognition module 301 includes:

[0105] The low-adhesion road surface recognition sub-module is used to recognize the road surface condition where the wheel is located as a low-adhesion road surface when the slip ratio of the wheel is greater than or equal to the preset slip ratio threshold;

[0106] The high-adhesion road surface recognition sub-module is used to recognize the road surface condition where the wheel is located as a high-adhesion road surface when the slip ratio of the wheel is less than the preset slip ratio threshold;

[0107] The first split road surface recognition sub-module is used to recognize the road surface condition where the front axle is located as a split road surface when the tires on both sides of the front axle are respectively on a low-adhesion road surface and a high-adhesion road surface;

[0108] The second split road surface recognition sub-module is used to recognize the road surface condition where the rear axle is located as a split road surface when the tires on both sides of the rear axle are respectively on a low-adhesion road surface and a high-adhesion road surface.

[0109] Optionally, when the vehicle is on a split road surface, the device further includes:

[0110] The torque reduction sub-module is used to reduce the four-wheel torque to the same value when the vehicle is in the driving state;

[0111] The torque increase sub-module is used to increase the four-wheel torque to the same value when the vehicle is in the braking state;

[0112] The torque amplification sub-module is used to gradually amplify the torque of the wheel on the high-adhesion road surface side after a delay of a preset time.

[0113] Optionally, the target slip ratio setting module 303 includes:

[0114] The first target slip ratio setting sub-module is used to increase the slip ratio setting value on the basis of the reference slip ratio to obtain the target slip ratio when the vehicle speed is lower than the preset vehicle speed threshold;

[0115] The second target slip ratio setting sub-module is used to reduce the slip ratio setting value on the basis of the reference slip ratio to obtain the target slip ratio when the vehicle speed is greater than or equal to the preset vehicle speed threshold;

[0116] The third target slip ratio setting sub-module is used to, when oversteering occurs, increase the slip ratio setting values of the two front axle wheels on the basis of the reference slip ratio to obtain the target slip ratios of the two front axle wheels;

[0117] The fourth target slip ratio setting sub-module is used to, when understeering occurs, increase the slip ratio setting values of the two rear axle wheels on the basis of the reference slip ratio to obtain the target slip ratios of the two rear axle wheels;

[0118] The fifth target slip ratio setting sub-module is used to, when the left rear wheel is about to enter a high-adhesion road surface, increase the slip ratio setting value of the left rear wheel on the basis of the reference slip ratio to obtain the target slip ratio of the left rear wheel;

[0119] The sixth target slip ratio setting sub-module is used to, when the right rear wheel is about to enter a high-adhesion road surface, increase the slip ratio setting value of the right rear wheel on the basis of the reference slip ratio to obtain the target slip ratio of the right rear wheel;

[0120] The seventh target slip ratio setting sub-module is used to, when the left front wheel is about to enter a high-adhesion road surface, increase the slip ratio setting value of the left front wheel on the basis of the reference slip ratio to obtain the target slip ratio of the left front wheel;

[0121] The eighth slip ratio setting sub-module is used to, when the right front wheel is about to enter a high-adhesion road surface, increase the slip ratio setting value of the right front wheel on the basis of the reference slip ratio to obtain the target slip ratio of the right front wheel;

[0122] The ninth slip ratio setting sub-module is used to periodically increase the single-wheel target slip ratio.

[0123] Optionally, the single-wheel target vehicle speed acquisition module 304 includes:

[0124] The first single-wheel target vehicle speed acquisition sub-module is used to, in the driving state, the single-wheel target wheel speed is the ratio of the vehicle speed to the difference between 1 and the target slip ratio;

[0125] The second single-wheel target vehicle speed acquisition sub-module is used to, in the braking state, the single-wheel target wheel speed is the product of the vehicle speed and the difference between 1 and the target slip ratio.

[0126] Optionally, the torque adjustment module 307 is specifically used for:

[0127] Using the vehicle control unit VCU to control the torque of the wheel by the difference between the feedforward control torque and the feedback control torque.

[0128] Optionally, the feedforward control torque is the difference between the actual torque of the motor and the rotational inertia torque; the feedback control torque is obtained by performing a PID closed-loop control on the difference in wheel speed change rate; the difference in wheel speed change rate is the difference between the actual wheel speed change rate and the target wheel speed change rate.

[0129] A slip ratio control device provided by an embodiment of the present application is used to control a vehicle with four-wheel independent drive. By using a road surface state recognition mode, a reference slip ratio acquisition module, a target slip ratio setting module, a single-wheel target vehicle speed acquisition module, a single-wheel speed difference acquisition module, a slip ratio control activation or deactivation module, and a torque adjustment module, it identifies the road surface state where each wheel is located according to the slip ratio of each wheel; obtains a reference slip ratio according to the vehicle mode, vehicle speed, and steering characteristics; sets the target slip ratio of each wheel based on the reference slip ratio, the vehicle speed, and the road surface state where each wheel is located; obtains the single-wheel target wheel speed of each wheel according to the target slip ratio of each wheel; obtains the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel; uses the single-wheel speed difference to judge the activation or deactivation of the slip ratio control of each wheel; when the slip ratio control of any wheel is activated, the vehicle control unit (VCU) is used to adjust the torque of the wheel so that the slip ratio of the wheel reaches the corresponding target slip ratio. Setting the target slip ratio according to the actual situation during vehicle driving and controlling the torque of each wheel through the VCU to make each wheel reach the target slip ratio can enable the vehicle to make full use of adhesion, enhance the grip, achieve continuous and stable acceleration or deceleration under working conditions such as uniform low adhesion, split road surfaces, and muddy road surfaces, and at the same time can effectively avoid vehicle deviation. Therefore, a slip ratio control method provided by an embodiment of the present application can better control a vehicle with four-wheel independent drive.

[0130] Electronic Device Embodiment

[0131] See Figure 4 , which is a schematic structural diagram of an electronic device provided by an embodiment of the present application, including:

[0132] A memory 11 for storing a computer program;

[0133] A processor 12 for implementing the steps of the slip ratio control method described in any of the above method embodiments when executing the computer program.

[0134] In this embodiment, the device can be an in-vehicle computer, a PC (Personal Computer), or a terminal device such as a smart phone, a tablet computer, a handheld computer, or a portable computer.

[0135] The device may include a memory 11, a processor 12, and a bus 13.

[0136] Among them, the memory 11 includes at least one type of readable storage medium, and the readable storage medium includes flash memory, hard disk, multimedia card, card-type memory (such as SD or DX memory, etc.), magnetic memory, magnetic disk, optical disc, etc. The memory 11 can be an internal storage unit of the device in some embodiments, such as the hard disk of the device. The memory 11 can also be an external storage device of the device in other embodiments, such as a plug-in hard disk equipped on the device, a SmartMedia Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. Further, the memory 11 can also include both the internal storage unit and the external storage device of the device. The memory 11 can be used not only to store application software installed on the device and various types of data, such as program codes for executing the slip ratio control method, etc., but also to temporarily store data that has been output or will be output.

[0137] The processor 12 can be a central processing unit (CPU), a controller, a microcontroller, a microprocessor or other data processing chips in some embodiments, and is used to run the program codes stored in the memory 11 or process data, such as program codes for executing the slip ratio control method, etc.

[0138] The bus 13 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of representation, Figure 4 only a thick line is used to represent it in the figure, but it does not mean that there is only one bus or one type of bus.

[0139] Further, the device can also include a network interface 14, and the network interface 14 can optionally include a wired interface and / or a wireless interface (such as a WI-FI interface, a Bluetooth interface, etc.), and is usually used to establish a communication connection between the device and other electronic devices.

[0140] Optionally, the device may further include a user interface 15, which may include a display, an input unit such as a keyboard, and optionally, the user interface 15 may further include a standard wired interface and a wireless interface. Optionally, in some embodiments, the display may be an LED display, a liquid crystal display, a touch liquid crystal display, and an OLED (Organic Light-Emitting Diode) toucher, etc. Among them, the display may also be appropriately referred to as a display screen or a display unit, which is used to display the information processed in the device and to display a visual user interface.

[0141] Figure 4 Only the device with components 11-15 is shown, and those skilled in the art can understand that Figure 4 the shown structure does not constitute a limitation on the device, and it may include fewer or more components than shown, or combine certain components, or have different component arrangements.

[0142] Vehicle Embodiment

[0143] The embodiment of the present application also provides a vehicle, which includes the memory and the processor in the above-mentioned electronic device embodiment.

[0144] It should be noted that the embodiments in this specification are all described in a progressive manner. The same or similar parts between the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the device, equipment, and vehicle embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiments. The device, equipment, and vehicle embodiments described above are only illustrative. The modules described as separate components may or may not be physically separated, and the components described as module prompts may or may not be physical modules, that is, they may be located in one place or distributed to multiple network modules. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative work.

[0145] As described above, it is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A slip ratio control method, characterized in that: For controlling a four-wheel independent drive vehicle, the method comprises: Identify the road surface condition of each wheel according to the slip rate of each wheel; Obtaining a baseline slip ratio based on vehicle mode, vehicle speed and steering characteristics; Setting a target slip ratio for each wheel based on the reference slip ratio, the vehicle speed, and the road surface condition on which each wheel is located; Obtaining a single-wheel target wheel speed of each wheel according to a target slip rate of each wheel; Obtaining a single wheel speed difference of each wheel according to the single wheel target wheel speed of each wheel; Determining activation or exit of each wheel slip control by using the single wheel speed difference; When the slip rate control of any wheel is activated, the vehicle controller VCU is used to adjust the torque of the wheel so that the slip rate of the wheel reaches the corresponding target slip rate.

2. The method according to claim 1, characterized in that The identifying the road surface state of each wheel according to the slip rate of each wheel includes: When the slip rate of the wheel is greater than or equal to a preset slip rate threshold, identifying the road surface state where the wheel is located as a low-adhesion road surface; When the slip rate of the wheel is less than a preset slip rate threshold, identifying the road surface state where the wheel is located as a high-adhesion road surface; When the tires on both sides of the front axle are on a low-adhesion road surface and a high-adhesion road surface respectively, the road surface state where the front axle is located is identified as an open road surface; When the tires on both sides of the rear axle are respectively on a low-adhesion road surface and a high-adhesion road surface, the road surface state where the rear axle is located is identified as an open road surface.

3. The method according to claim 2, characterized in that When the vehicle is on an open road, the method further includes: When the vehicle is in driving state, the torque of the four wheels is reduced to the same value; When the vehicle is in braking state, the torque of the four wheels is increased to the same value; After a preset time delay, the torque of the wheel on the high-adhesion road side is gradually increased.

4. The method according to claim 1, characterized in that The setting of the target slip rate of each wheel based on the reference slip rate, the vehicle speed and the road surface condition of each wheel includes: When the vehicle speed is lower than a preset vehicle speed threshold, increasing a slip ratio setting value based on the reference slip ratio to obtain a target slip ratio; When the vehicle speed is greater than or equal to a preset vehicle speed threshold, reducing a slip ratio setting value based on the reference slip ratio to obtain a target slip ratio; When oversteering occurs, the slip rate setting value of the two wheels on the front axle is increased based on the reference slip rate to obtain the target slip rate of the two wheels on the front axle; When understeering occurs, the slip rate setting value of the two wheels on the rear axle is increased based on the reference slip rate to obtain the target slip rate of the two wheels on the rear axle; When the left rear wheel is about to enter a high-adhesion road surface, the slip rate setting value of the left rear wheel is increased based on the reference slip rate to obtain a target slip rate of the left rear wheel; When the right rear wheel is about to enter a high-adhesion road surface, the slip rate setting value of the right rear wheel is increased based on the reference slip rate to obtain a target slip rate of the right rear wheel; When the left front wheel is about to enter a high-adhesion road surface, the slip rate setting value of the left front wheel is increased based on the reference slip rate to obtain a target slip rate of the left front wheel; When the right front wheel is about to enter a high-adhesion road surface, the slip rate setting value of the right front wheel is increased based on the reference slip rate to obtain a target slip rate of the right front wheel; Periodically increase the target slip rate of a single wheel.

5. The method according to claim 1, characterized in that The step of obtaining a single-wheel target wheel speed of each wheel according to the target slip rate of each wheel includes: In the driving state, the single wheel target speed is the ratio of the vehicle speed to 1 minus the target slip ratio; In the braking state, the single wheel target speed is the product of the vehicle speed and 1 minus the target slip ratio.

6. The method according to claim 1, characterized in that The method of changing the torque of the wheel by using the vehicle controller VCU comprises: The vehicle controller VCU uses the difference between the feedforward control torque and the feedback control torque to control the torque of the wheel.

7. The method according to claim 6, characterized in that The feedforward control torque is the difference between the actual torque of the motor and the rotational inertia torque; the feedback control torque is obtained by PID closed-loop control of the wheel speed change rate difference; the wheel speed change rate difference is the difference between the actual wheel speed change rate and the target wheel speed change rate.

8. A slip ratio control device, characterized in that: For controlling a four-wheel independent drive vehicle, the device comprises: A road surface state recognition module, used to recognize the road surface state of each wheel according to the slip rate of each wheel; A reference slip ratio acquisition module, used for acquiring a reference slip ratio according to a vehicle mode, a vehicle speed and a steering characteristic; a target slip ratio setting module, configured to set a target slip ratio for each wheel based on the reference slip ratio, the vehicle speed, and the road surface condition on which each wheel is located; A single-wheel target vehicle speed acquisition module is used to acquire the single-wheel target wheel speed of each wheel according to the target slip rate of each wheel; A single-wheel speed difference acquisition module, used for acquiring the single-wheel speed difference of each wheel according to the single-wheel target wheel speed of each wheel; a slip rate control activation or exit module, used to determine activation or exit of slip rate control of each wheel by using the single wheel speed difference; The torque adjustment module is used to adjust the torque of any wheel using the vehicle controller VCU when the slip rate control of the wheel is activated, so that the slip rate of the wheel reaches the corresponding target slip rate.

9. An electronic device, characterized in that: include: Memory for storing computer programs; A processor, configured to implement the steps of the slip ratio control method according to any one of claims 1 to 7 when executing the computer program.

10. A vehicle, characterized in that: Comprising the electronic device as claimed in claim 9.

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