Method for determining road adhesion state, device thereof, vehicle control unit and vehicle

Abstract

The application discloses a kind of determination method and device of road surface adhesion state, whole vehicle controller and vehicle, determination method includes: according to the longitudinal acceleration of vehicle, lateral acceleration, at least one parameter in the torque and slip rate of driving wheel, determine the current road surface adhesion state of vehicle;Road surface adhesion state at least contains first road surface adhesion state and second road surface adhesion state, the minimum road surface adhesion coefficient corresponding to first road surface adhesion state is greater than the maximum road surface adhesion coefficient corresponding to second road surface adhesion state.By according to the longitudinal acceleration of vehicle, lateral acceleration, the torque and slip rate of driving wheel these basic parameters of vehicle, determine the current road surface adhesion state of vehicle is in which road surface adhesion state, to avoid the problem that vehicle control mutation is caused due to using adhesion coefficient and appearing larger mutation, can be stably and reliably as the reference index for the torque distribution of driving wheel.

Description

Technical Field

[0001] This application relates to the field of transportation vehicles, and more specifically to a method and apparatus for determining road surface adhesion state, a vehicle controller, and a vehicle. Background Technology

[0002] Currently, the assessment of road surface adhesion is mostly based on the estimation of the road surface adhesion coefficient, which is typically estimated using dynamic methods. The road surface adhesion coefficient estimated by dynamic methods is usually the wheel-to-road utilization adhesion coefficient. However, during the estimation process, the wheel-to-road utilization adhesion coefficient can experience significant abrupt changes due to interference factors such as, but not limited to, sudden increases in wheel speed and large axle load transfers. This leads to instability in the reliability of the road surface adhesion coefficient estimated by dynamic methods. Summary of the Invention

[0003] This application is made to address at least one of the aforementioned problems. According to a first aspect of this application, a method for determining road surface adhesion state is provided, the method comprising: determining the current road surface adhesion state of a vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio; wherein the road surface adhesion state includes at least a first road surface adhesion state and a second road surface adhesion state, and the minimum road surface adhesion coefficient corresponding to the first road surface adhesion state is greater than the maximum road surface adhesion coefficient corresponding to the second road surface adhesion state.

[0004] In one embodiment of this application, the first road surface adhesion state corresponds to a first road surface adhesion coefficient range, and the second road surface adhesion state corresponds to a second road surface adhesion coefficient range; wherein, the minimum value of the first road surface adhesion coefficient range is greater than the maximum value of the second road surface adhesion coefficient range.

[0005] In one embodiment of this application, determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio, includes: determining the current road surface adhesion state of the vehicle based on the torque and slip ratio of the vehicle's drive wheels; if the torque and slip ratio of all drive wheels of the vehicle are in a first state, then determining that the vehicle is in the first road surface adhesion state; wherein, the first state includes at least: the slip ratio of the drive wheels is greater than or equal to a first slip ratio threshold, and the net torque of the drive wheels is greater than or equal to a first threshold threshold.

[0006] In one embodiment of this application, the first threshold is determined based on the load of the drive wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state.

[0007] In one embodiment of this application, the first state further includes at least: the net torque of the drive wheel is greater than or equal to a first set threshold.

[0008] In one embodiment of this application, determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheel, and slip ratio, includes: determining the current road surface adhesion state of the vehicle based on the longitudinal acceleration of the drive wheel; and determining that the vehicle is in the first road surface adhesion state if the longitudinal acceleration of the vehicle is greater than or equal to a first longitudinal acceleration threshold.

[0009] In one embodiment of this application, determining the current road surface adhesion state of the vehicle based on at least one of the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio includes: determining the current road surface adhesion state of the vehicle based on the lateral acceleration of the vehicle's drive wheels; and determining that the vehicle is in the first road surface adhesion state if the lateral acceleration of the vehicle satisfies a first lateral condition.

[0010] In one embodiment of this application, the first lateral condition includes: the actual lateral acceleration of the vehicle is greater than or equal to a first actual threshold, and the ideal lateral acceleration of the vehicle is greater than or equal to a first ideal threshold.

[0011] In one embodiment of this application, determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio, includes: determining the current road surface adhesion state of the vehicle based on the vehicle's longitudinal acceleration, lateral acceleration, torque of each drive wheel, and slip ratio; if the torque and slip ratio of at least one drive wheel of the vehicle are in a second state, the longitudinal acceleration of the vehicle is less than or equal to a second longitudinal acceleration threshold, and the lateral acceleration of the vehicle satisfies a second lateral condition, then the vehicle is determined to be in the second road surface adhesion state; wherein, the second state includes at least: the slip ratio of the drive wheel is less than or equal to a second slip ratio threshold, and the net slip ratio of the drive wheel is less than or equal to a second threshold threshold.

[0012] In one embodiment of this application, the second threshold is determined based on the load of the drive wheel, the rolling radius, and the maximum road adhesion coefficient corresponding to the second road adhesion state.

[0013] In one embodiment of this application, the second state further includes at least: the net torque of the drive wheel is greater than or equal to a second preset threshold.

[0014] In one embodiment of this application, the second lateral condition includes: the actual lateral acceleration of the vehicle is less than or equal to a second actual threshold, and the ideal lateral acceleration of the vehicle is less than or equal to a second ideal threshold.

[0015] In one embodiment of this application, the determination method further includes: acquiring the vehicle speed; and when the vehicle speed is greater than a vehicle speed threshold, determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheel, and slip ratio.

[0016] In one embodiment of this application, the determination method further includes: a method for determining the switching between a first road surface adhesion state and a second road surface adhesion state.

[0017] In one embodiment of this application, the method for determining the switching between the first road surface adhesion state and the second road surface adhesion state includes: when the current road surface adhesion state of the vehicle is the first road surface adhesion state, and when it is determined at least twice consecutively that the vehicle is in the second road surface adhesion state, switching the current road surface adhesion state of the vehicle to the second road surface adhesion state; or, when the current road surface adhesion state of the vehicle is the second road surface adhesion state, and when it is determined at least twice consecutively that the vehicle is in the first road surface adhesion state, switching the current road surface adhesion state of the vehicle to the first road surface adhesion state.

[0018] According to a second aspect of this application, a device for determining road surface adhesion state is also provided. The device includes a storage medium and a processor. The storage medium stores a computer program executed by the processor. When the computer program is executed by the processor, the processor causes the processor to perform any of the above-described methods for determining road surface adhesion state.

[0019] According to a third aspect of this application, a vehicle controller is also provided, the vehicle controller including: a device for determining any of the above-mentioned road surface adhesion states.

[0020] According to a fourth aspect of this application, a vehicle is also provided, the vehicle comprising: a vehicle body, and any of the above-described vehicle controllers disposed on the vehicle body.

[0021] According to the method and apparatus for determining road surface adhesion state, vehicle controller, and vehicle provided in this application, the current road surface adhesion state of the vehicle is determined based on at least one parameter among the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. This determines whether the vehicle is in a first road surface adhesion state (such as, but not limited to, a higher adhesion state) or a second road surface adhesion state (a lower adhesion state). Compared to the road surface adhesion coefficient estimated by existing dynamic methods, this application determines the current road surface adhesion state of the vehicle based on fundamental vehicle parameters such as longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. This avoids the problem of sudden changes in vehicle control due to large abrupt changes in the adhesion coefficient, and provides a stable and reliable reference index for distributing torque to the drive wheels. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating a method for determining road surface adhesion state according to an embodiment of the present invention;

[0024] Figure 2 A flowchart illustrating a method for determining road surface adhesion state according to another embodiment of the present invention;

[0025] Figure 3 A flowchart illustrating a method for determining road surface adhesion state according to another embodiment of the present invention;

[0026] Figure 4 This is a schematic block diagram illustrating the switching of the display attachment state of a vehicle according to an embodiment of the present invention;

[0027] Figure 5 This is a schematic block diagram of a device for determining the road surface adhesion state according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic block diagram of a vehicle controller according to an embodiment of the present invention;

[0029] Figure 7 This is a schematic block diagram of a vehicle according to an embodiment of the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the present invention more apparent, exemplary embodiments according to the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. It should be understood that the present invention is not limited to the exemplary embodiments described herein. Based on the embodiments of the present invention described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of the present invention.

[0031] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0032] It should be understood that the invention can be embodied in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0033] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “compose” and / or “comprising,” when used in this specification, confirm the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0034] To fully understand this invention, a detailed structure will be presented in the following description to illustrate the technical solution proposed by this invention. Optional embodiments of the invention are described in detail below; however, in addition to these detailed descriptions, the invention may have other embodiments.

[0035] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0036] First, let me introduce the application scenario of the method for determining the road surface adhesion state illustrated in this application. This method is applied to the power control process of a vehicle, specifically, to determine the current road surface adhesion state of the vehicle.

[0037] refer to Figure 1This application provides a method for determining road surface adhesion state. The method includes: determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheel, and slip ratio; wherein the road surface adhesion state includes at least a first road surface adhesion state and a second road surface adhesion state, and the minimum road surface adhesion coefficient corresponding to the first road surface adhesion state is greater than the maximum road surface adhesion coefficient corresponding to the second road surface adhesion state.

[0038] In the above-described scheme, the current road surface adhesion state of the vehicle is determined based on at least one parameter among the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. This determines whether the vehicle is in a first road surface adhesion state (higher adhesion) or a second road surface adhesion state (lower adhesion). Compared to the road surface adhesion coefficient estimated by existing dynamic methods, this embodiment determines the current road surface adhesion state based on fundamental vehicle parameters such as longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. This avoids the problem of sudden changes in vehicle control due to large abrupt changes in the adhesion coefficient, and provides a stable and reliable reference index for distributing torque to the drive wheels. The following detailed description of each step, in conjunction with the accompanying drawings, further illustrates these steps.

[0039] The road surface adhesion state includes at least a first road surface adhesion state and a second road surface adhesion state, wherein the first road surface adhesion state is superior to the second road surface adhesion state. It should be explained that the road surface adhesion states here are pre-set, and there can be at least two road surface adhesion states. For example, this application will illustrate this with two road surface adhesion states (the first road surface adhesion state and the second road surface adhesion state, respectively). It should be noted that the pre-set road surface adhesion states in this application embodiment are not limited to two; in addition, they can be any value of at least three road surface adhesion states, such as three or four road surface adhesion states.

[0040] The range of road adhesion coefficients varies depending on the road surface adhesion condition; some conditions have higher coefficients, while others have lower coefficients. In the example below, the minimum road adhesion coefficient for the first road surface adhesion condition is higher than the maximum coefficient for the second condition. For example,... Figures 3-4 The term "high adhesion" or "high adhesion state" refers to the first surface adhesion state, such as... Figures 3-4 The low adhesion or low adhesion state in the text refers to the second road surface adhesion state.

[0041] For example, the road adhesion coefficient corresponding to each road surface adhesion state can be a specific value. In this case, the minimum and maximum road adhesion coefficients corresponding to each road surface adhesion state are both fixed values. In other embodiments, the road adhesion coefficient corresponding to each road surface adhesion state can correspond to a range of road surface adhesion coefficients. For example, the first road surface adhesion state can correspond to a first range of road surface adhesion coefficients, and the second road surface adhesion state can correspond to a second range of road surface adhesion coefficients, wherein the minimum value of the first range of road surface adhesion coefficients is greater than the maximum value of the second range of road surface adhesion coefficients. This not only ensures that the minimum road surface adhesion coefficient of the first road surface adhesion state is greater than the maximum road surface adhesion coefficient of the second road surface adhesion state, but also ensures that each road surface adhesion state corresponds to a relatively wide range of road surface adhesion coefficients, preventing excessive switching of road surface adhesion states.

[0042] The drive wheels of a vehicle refer to the wheels that provide driving torque to the vehicle. The method for determining the road surface adhesion state shown in the embodiments of this application can be applied to independent four-wheel drive vehicles, that is, vehicles equipped with four independently driven drive wheels. Each drive wheel can be provided with driving torque by a drive motor or engine. That is, the method for determining the road surface adhesion state shown in the embodiments of this application can be applied to vehicles such as, but not limited to, electric vehicles, hybrid vehicles, or gasoline vehicles.

[0043] When determining the current road surface adhesion state of a vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, various combinations of methods are possible. For example, the current road surface adhesion state can be determined based on only one of these parameters; for instance, it can be determined whether the vehicle is currently in a first road surface adhesion state based solely on either the longitudinal or lateral acceleration. Alternatively, the current road surface adhesion state can be determined based on only two of these parameters; for instance, it can be determined whether the vehicle is currently in a first road surface adhesion state based solely on the drive wheel torque and slip ratio. Currently, the current road surface adhesion state can also be determined based on any three or all of these parameters. In this embodiment of the application, as long as it is possible to determine whether the vehicle is currently in or not in a certain road surface adhesion state based on at least one of the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, it falls within the protection scope of this embodiment of the application. Several determination methods are exemplarily described below.

[0044] For example, refer to Figure 2Determining the vehicle's current road surface adhesion state based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, may include: determining the vehicle's current road surface adhesion state based on the torque and slip ratio of the vehicle's drive wheels. If the torque and slip ratio of all the vehicle's drive wheels are in a first state, then the vehicle is determined to be in a first road surface adhesion state. The first state may at least include: the drive wheel slip ratio being greater than or equal to a first slip ratio threshold, and the drive wheel net torque being greater than or equal to a first threshold threshold. That is, the drive wheel slip ratio is high, and the drive wheel net torque is high.

[0045] For example, when a vehicle has four drive wheels, if the net torque and slip ratio of all four drive wheels are in the first state, then the vehicle can be directly determined to be in the first road surface adhesion state. The slip ratio of the drive wheels is determined based on the wheel speed and vehicle speed. Specifically, the slip ratio can be calculated as (wheel speed - vehicle speed) / wheel speed * 100%. In a more efficient method, the wheel speed can be divided by zero for protection. The net torque of the drive wheel refers to the driving torque output by the motor or engine to the drive system minus the hydraulic wheel-end torque of that drive wheel; that is, the net torque of the drive wheel equals the driving torque of the drive wheel minus the braking torque. It should be understood that the method for determining whether the first state is satisfied based on the torque of the vehicle's drive wheels is not limited to using the net torque of the drive wheels. Other methods can also be used. For example, torque parameters such as actual torque can also be used as a method to determine whether the first state is satisfied.

[0046] The first threshold value can be determined in various ways, and it is related to the current load on the drive wheel and the minimum road adhesion coefficient corresponding to a pre-set first road surface adhesion state. For example, the first threshold value can be determined based on the load on the drive wheel, its rolling radius, and the minimum road adhesion coefficient corresponding to the first road surface adhesion state. For example, the first threshold value can be the absolute value of the product of the vertical load on the drive wheel, its rolling radius, and the minimum road adhesion coefficient corresponding to the first road surface adhesion state. It should be noted that the minimum road adhesion coefficient corresponding to the first road surface adhesion state is a calibrated value, a parameter pre-determined through testing, simulation, etc. The minimum road adhesion coefficient corresponding to the first road surface adhesion state can be the minimum value within the range of first road surface adhesion coefficients corresponding to the first road surface adhesion state. Of course, in other embodiments, the first threshold value can also be determined based on the first road surface adhesion state of the drive wheel and other vehicle parameters.

[0047] For example, the aforementioned first state may further include: the slip ratio of the drive wheels is greater than or equal to a first slip ratio threshold. Here, the first threshold is a calibrated value pre-set through methods such as, but not limited to, testing and simulation. The reason for setting a first threshold is that it is not affected by load during vehicle operation. Only when the net torque of the drive wheels is greater than the first threshold can the judgment process for determining whether it is a high torque be triggered, thereby improving the accuracy of high torque judgment. When all drive wheels of the vehicle are in the first state of high slip ratio and high torque, the entire vehicle is determined to be in the first road surface adhesion state.

[0048] like Figure 2 As shown, when determining the current road surface adhesion state of a vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, the current road surface adhesion state can be determined based on the longitudinal acceleration of the drive wheels. If the vehicle's longitudinal acceleration is greater than or equal to a first longitudinal acceleration threshold, the vehicle can be determined to be in a first road surface adhesion state. That is, the vehicle's current longitudinal acceleration is relatively large, since a vehicle can only output a large longitudinal acceleration when it is in a high road surface adhesion state. Therefore, one of the necessary conditions for a vehicle to output a large longitudinal acceleration is that it is in a high road surface adhesion state. Thus, when the vehicle's longitudinal acceleration is greater than or equal to the first longitudinal acceleration threshold, it can be directly determined that the vehicle is in a first road surface adhesion state.

[0049] like Figure 2 As shown, when determining the current road surface adhesion state of a vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of each drive wheel, and slip ratio, the current road surface adhesion state can be determined based on the lateral acceleration of the drive wheels. If the vehicle's lateral acceleration satisfies a first lateral condition, the vehicle can be determined to be in a first road surface adhesion state. That is, the vehicle's current lateral acceleration is relatively large, since a vehicle can only output a large lateral acceleration when it is in a high road surface adhesion state. Therefore, one of the necessary conditions for the vehicle to output a large lateral acceleration is that the vehicle is in a high road surface adhesion state. Thus, when the vehicle's lateral acceleration is greater than or equal to a first longitudinal acceleration threshold, the vehicle can be directly determined to be in a first road surface adhesion state.

[0050] When determining the first lateral condition, it is related to the vehicle's actual lateral acceleration and ideal lateral acceleration. For example, the first lateral condition may include: the vehicle's actual lateral acceleration is greater than or equal to a first actual threshold, and the vehicle's ideal lateral acceleration is greater than or equal to a first ideal threshold. That is, a larger actual lateral acceleration generally results in a larger ideal lateral acceleration. The vehicle's actual lateral acceleration can be determined based on the vehicle's operating state, and the vehicle's ideal lateral acceleration can be determined based on the steering wheel's rotation angle. It should be understood that the method of setting the first lateral condition is not limited to the method shown above; other methods can also be used. For example, only the vehicle's actual lateral acceleration and actual threshold can be determined, without determining the ideal lateral acceleration and ideal threshold.

[0051] like Figure 2 As shown, determining the current road surface adhesion state of a vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio, may further include: determining the current road surface adhesion state of the vehicle based on its longitudinal acceleration, lateral acceleration, torque of each drive wheel, and slip ratio. If at least one drive wheel of the vehicle has a torque and slip ratio in a second state, the vehicle's longitudinal acceleration is less than or equal to a second longitudinal acceleration threshold, and the vehicle's lateral acceleration satisfies a second lateral condition, then the vehicle is determined to be in a second road surface adhesion state. The second state may include at least: the slip ratio of the drive wheels is less than or equal to a second slip ratio threshold, and the net torque of the drive wheels is less than or equal to a second threshold. That is, when the drive wheels are in the second state, the slip ratio of the drive wheels is low, and the net torque of the drive wheels is low.

[0052] In other words, a vehicle can be determined to be in a second road surface adhesion state only if at least one drive wheel's net torque and slip ratio are in the second state (specifically, the net torque and slip ratio of one, two, three, or four drive wheels are in the second state), the vehicle's longitudinal acceleration is small, and the vehicle's lateral acceleration meets the small second lateral condition. Otherwise, the vehicle's current displayed adhesion state remains unchanged. It should be explained that the vehicle's displayed adhesion state refers to the road surface adhesion state currently displayed by the vehicle. This can be the road surface adhesion state input to the vehicle controller as a torque distribution reference, the first road surface adhesion state mentioned above, or the second road surface adhesion state. When distributing torque to each drive wheel, the vehicle controller needs to ensure that the utilization coefficient of adhesion for each drive wheel is not greater than the maximum road surface adhesion coefficient corresponding to the vehicle's current displayed adhesion state. It should be explained that the utilization coefficient of adhesion refers to the degree to which the wheel-end driving force of the current drive wheel utilizes the road surface adhesion coefficient. Figure 3 and Figure 4Initially, the system can be assumed to be in the first road surface adhesion state, which is a high-adhesion state. It should be understood that the method for determining whether the second state is satisfied based on the torque of the vehicle's drive wheels is not limited to using the net torque of the drive wheels; other methods can also be used. For example, torque parameters such as actual torque can also be used as a method to determine whether the second state is satisfied.

[0053] It is important to note that both the second and first slip ratio thresholds are calibrated values, meaning they are parameters determined in advance through testing, simulation, or other methods. The first slip ratio threshold must be greater than the second slip ratio threshold. That is, when the drive wheel is in the second state, its slip ratio is considered low.

[0054] The second threshold can be determined in various ways, and it is related to the current load on the drive wheel and the maximum road adhesion coefficient corresponding to a pre-set second road adhesion state. For example, the second threshold can be determined based on the load on the drive wheel, its rolling radius, and the maximum road adhesion coefficient corresponding to the second road adhesion state. For example, the second threshold can be the absolute value of the product of the vertical load on the drive wheel, its rolling radius, and the maximum road adhesion coefficient corresponding to the second road adhesion state. It should be noted that the maximum road adhesion coefficient corresponding to the second road adhesion state is a calibrated value, a parameter pre-determined through testing, simulation, etc. The maximum road adhesion coefficient corresponding to the second road adhesion state can be the maximum value within the range of second road adhesion coefficients corresponding to the second road adhesion state. Of course, in other embodiments, the second threshold can also be determined based on the second road adhesion state of the drive wheel and other vehicle parameters.

[0055] For example, the second state described above may at least include: the net torque of the drive wheels is greater than or equal to a second preset threshold. The second preset threshold is a calibrated value pre-set through methods such as, but not limited to, testing and simulation. The reason for setting a second preset threshold is that it is not affected by load or vehicle speed during vehicle operation. Only when the net torque of the drive wheels is greater than the second preset threshold can the judgment process for determining whether it is a high torque be triggered, preventing large errors in judging low torque due to excessively low net torque and vehicle speed, thereby improving the accuracy of judging low torque. When at least one drive wheel of the vehicle is in the second state of low slip ratio and low torque, the entire vehicle is determined to be in the second road surface adhesion state. It should be noted that both the second and first preset thresholds are calibrated values, i.e., parameters pre-determined through testing, simulation, etc. The second preset threshold must be less than the first preset threshold.

[0056] Various methods can be used to determine the second lateral condition. For example, the second lateral condition may include: the vehicle's actual lateral acceleration is less than or equal to a second actual threshold, and the vehicle's ideal lateral acceleration is less than or equal to a second ideal threshold. It should be noted that the second actual threshold, the second ideal threshold, the first actual threshold, and the first ideal threshold are all calibrated values, parameters pre-determined through testing, simulation, etc. Specifically, the second actual threshold is less than the first actual threshold, and the second ideal threshold is less than the first ideal threshold. That is, the vehicle's lateral acceleration when the first lateral condition is met must be greater than the lateral acceleration when the second lateral condition is met. It should be understood that the method for setting the second lateral condition is not limited to the methods shown above; other methods can also be used. For example, only the vehicle's actual lateral acceleration and actual threshold can be determined, without determining the ideal lateral acceleration and ideal threshold.

[0057] In a preferred embodiment, the determination method may further include: acquiring the vehicle speed; and when the vehicle speed is greater than a speed threshold, determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio. That is, the above method is used only when the vehicle speed is relatively high, determining the current road surface adhesion state based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio. If the vehicle speed does not exceed the speed threshold, the above method is not used to determine the current road surface adhesion state based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio. This prevents the road surface adhesion state determined by the above method from being inaccurate due to excessively low vehicle speed, thereby improving the accuracy of road surface adhesion state determination. Figure 3 As shown, the vehicle is in motion when its speed exceeds the speed threshold. Otherwise, the vehicle's current display attachment status remains unchanged.

[0058] In some embodiments, the determining method may further include: determining the vehicle's displayed adhesion state based on the determined current road surface adhesion state. That is, after determining the vehicle's current road surface adhesion state each time, it is then determined whether to change the vehicle's displayed adhesion state. It should be explained that the vehicle's displayed adhesion state refers to the road surface adhesion state currently displayed by the vehicle. This can be the road surface adhesion state input to the vehicle controller as a torque distribution reference, the aforementioned first road surface adhesion state, or a second road surface adhesion state. When distributing torque to each drive wheel, the vehicle controller needs to ensure that the utilization coefficient of adhesion for each drive wheel is not greater than the maximum road surface adhesion coefficient corresponding to the vehicle's current displayed adhesion state. It should be explained that the utilization coefficient of adhesion refers to the degree to which the wheel-end driving force of the current drive wheel utilizes the road surface adhesion coefficient. (Reference) Figure 3 and Figure 4 Initially, it can be assumed to be the first road surface adhesion state, which is the high adhesion state.

[0059] In some embodiments, the determination method may further include optimizing the switching conditions for the vehicle's current road surface adhesion state to switch from one road surface adhesion state to another. For example, the determination method may further include a method for determining the switch between a first road surface adhesion state and a second road surface adhesion state. When switching between the first road surface adhesion state and the second road surface adhesion state, the vehicle's current road surface adhesion state can be determined based on at least one determined road surface adhesion state. Specifically, the vehicle's current road surface adhesion state can be determined based on any one, two, three, or more determined road surface adhesion states.

[0060] For example, the method for determining the switching between the first and second road surface adhesion states may include: when the vehicle's current road surface adhesion state is the first road surface adhesion state, the vehicle's current road surface adhesion state is switched to the second road surface adhesion state only after it is determined that the vehicle is in the second road surface adhesion state at least twice consecutively. Specifically, a first counting threshold can be set, which can be any value greater than 2. When the vehicle's current road surface adhesion state is the first road surface adhesion state, the vehicle's current road surface adhesion state is switched from the first road surface adhesion state to the second road surface adhesion state only after it is determined that the vehicle is in the second road surface adhesion state for a consecutive first counting threshold number of times. Otherwise, the vehicle's current road surface adhesion state remains unchanged as the current first road surface adhesion state. This prevents the vehicle's current road surface adhesion state from switching too frequently, thus maintaining a stable and reliable reference indicator for distributing torque to the drive wheels.

[0061] In another embodiment, the method for determining the switching between the first and second road surface adhesion states may further include: when the vehicle's current road surface adhesion state is the second road surface adhesion state, the vehicle's current road surface adhesion state is switched to the first road surface adhesion state only if it is determined that the vehicle is in the first road surface adhesion state at least twice consecutively. Specifically, a second counting threshold can be set, which can be any value greater than 2. When the vehicle's current road surface adhesion state is the second road surface adhesion state, the vehicle's current road surface adhesion state is switched from the second road surface adhesion state to the first road surface adhesion state only if it is determined that the vehicle is in the first road surface adhesion state for at least a consecutive second counting threshold number of times. Otherwise, the vehicle's current road surface adhesion state remains unchanged as the current second road surface adhesion state. This prevents the vehicle's current road surface adhesion state from switching too frequently, thus maintaining a stable and reliable reference indicator for distributing torque to the drive wheels.

[0062] The current road surface adhesion state of the vehicle can be the displayed adhesion state currently output by the vehicle, serving as a reference indicator for distributing torque to the drive wheels. Corresponding to the determined current road surface adhesion state, in some embodiments, the determination method may further include optimizing the switching conditions for changing the vehicle's displayed adhesion state from one road surface adhesion state to another. For example, the determination method may further include: when the vehicle's displayed adhesion state is a first road surface adhesion state, the vehicle's displayed adhesion state is switched to the second road surface adhesion state only if the vehicle is determined to be in the second road surface adhesion state at least twice consecutively. Specifically, a first counting threshold can be set, which can be any value greater than 2. When the vehicle's displayed adhesion state is the first road surface adhesion state, the vehicle's displayed adhesion state is switched from the first road surface adhesion state to the second road surface adhesion state only if the vehicle is determined to be in the second road surface adhesion state for a consecutive first counting threshold number of times. Otherwise, the vehicle's displayed adhesion state remains unchanged as the current first road surface adhesion state. This prevents the displayed adhesion state from switching too frequently, maintaining a stable and reliable reference indicator for distributing torque to the drive wheels.

[0063] In other embodiments, the determination method may further include: when the vehicle's displayed attachment state is a second road surface attachment state, switching the vehicle's displayed attachment state to the first road surface attachment state only if the vehicle is determined to be in the first road surface attachment state at least twice consecutively. Specifically, a second counting threshold can be set, which can be any value greater than 2. When the vehicle's displayed attachment state is the second road surface attachment state, the vehicle's displayed attachment state is only switched from the second road surface attachment state to the first road surface attachment state if the vehicle is determined to be in the first road surface attachment state for at least a consecutive second counting threshold number of times. Otherwise, the vehicle's displayed attachment state remains unchanged as the current second road surface attachment state. This prevents the displayed attachment state from switching too frequently, maintaining a stable and reliable reference indicator for distributing torque to the drive wheels.

[0064] The following is in conjunction with the appendix Figures 3-4 For example, a specific application method is introduced. This road surface adhesion recognition method, applicable to four-wheel independent drive, mainly determines the current road surface adhesion state (high adhesion / low adhesion) of the vehicle by considering four aspects: the actual wheel-end torque of the drive wheels, vehicle speed, slip ratio, and overall vehicle acceleration. The overall idea of ​​this recognition method is as follows:

[0065] (1) Determination of low adhesion of the whole vehicle: Taking the left front wheel as an example, if the net torque of the left front wheel is low and the left front wheel has a high slip ratio, then the left front wheel is determined to be in the second state; the situation of other wheels is the same as above, and will not be repeated. When the vehicle is in motion, if one of the four wheels is in the second state and the longitudinal acceleration and lateral acceleration of the whole vehicle are both small, then the current road surface adhesion state of the vehicle is determined to be low adhesion state.

[0066] (2) Determination of overall vehicle high adhesion: Taking the left front wheel as an example, if the net torque of the left front wheel is high and the left front wheel has a low slip ratio, then the left front wheel is determined to be in the first state; the situation of other wheels is the same as above, and will not be repeated. When the vehicle is in motion, if all four wheels are in the first state or have a large longitudinal acceleration or a large lateral acceleration, then the current road surface adhesion state of the vehicle is determined to be a high adhesion state.

[0067] The methods for determining whether a vehicle is in motion include the following: high torque, low torque, high slip ratio, low slip ratio, large longitudinal acceleration, small longitudinal acceleration, large lateral acceleration, small lateral acceleration, and the determination of whether the vehicle is in motion.

[0068] 1) Determining high or low wheel slip ratio using flags. Taking the left front wheel as an example (the situation for other wheels is the same and will not be repeated), if the left front wheel slip ratio is >= threshold 1 (the first slip ratio threshold), then the left front wheel is judged to have a high slip ratio; if the left front wheel slip ratio is <= threshold 2 (the second slip ratio threshold), then the left front wheel is judged to have a low slip ratio. Here, threshold 1 and threshold 2 are both calibrated values, which are determined in advance through methods such as, but not limited to, testing and simulation.

[0069] 2) Determining the current wheel-end torque magnitude flag. Taking the left front wheel as an example (the situation for other wheels is the same and will not be repeated), if the net torque of the left front wheel is >= threshold 3 (first set threshold) and the net torque of the left front wheel is >= threshold 4 (first threshold threshold), then the left front wheel is judged to have high torque; if the net torque of the left front wheel is >= threshold 5 (second set threshold) and the net torque of the left front wheel is <= threshold 6 (second threshold threshold), then the left front wheel is judged to have low torque.

[0070] Wherein, the net torque of the left front wheel = the torque at the motor end of the left front wheel - the torque at the hydraulic end of the left front wheel;

[0071] Threshold 4 = |left front wheel load * rolling radius * minimum road adhesion coefficient for identifying high adhesion|;

[0072] Threshold 6 = |Left front wheel load * Rolling radius * Maximum road adhesion coefficient for identifying low adhesion|;

[0073] Threshold 3, threshold 5, minimum road adhesion coefficient for identifying high adhesion (minimum road adhesion coefficient corresponding to the first road adhesion state), and maximum road adhesion coefficient for identifying low adhesion (maximum road adhesion coefficient corresponding to the second road adhesion state) are all calibrated values, which are determined in advance through methods such as, but not limited to, testing and simulation.

[0074] 3) Determine the current magnitude and status of the vehicle's acceleration.

[0075] If the actual lateral acceleration of the vehicle is less than or equal to threshold 7 (second actual threshold) and the ideal lateral acceleration is less than or equal to threshold 8 (second ideal threshold), then the vehicle is judged to have small lateral acceleration; if the actual lateral acceleration of the vehicle is greater than or equal to threshold 9 (first actual threshold) and the ideal lateral acceleration is greater than or equal to threshold 10 (first ideal threshold), then the vehicle is judged to have large lateral acceleration. The ideal lateral acceleration is obtained by multiplying the ideal yaw rate by the vehicle speed.

[0076] If the longitudinal acceleration of the whole vehicle is less than or equal to threshold 11 (the second longitudinal acceleration threshold), the whole vehicle is judged to have small longitudinal acceleration; if the longitudinal acceleration of the whole vehicle is greater than or equal to threshold 12 (the first longitudinal acceleration threshold), the whole vehicle is judged to have large longitudinal acceleration.

[0077] 4) Vehicle movement determination. If the vehicle speed is greater than the threshold 13 (vehicle speed threshold), then the vehicle is determined to be in motion.

[0078] 5) Switching of road surface adhesion status. (Reference) Figure 4 The vehicle's displayed adhesion status uses high adhesion as the default adhesion status. The road surface adhesion status is switched according to the conditions shown in Tables 1 and 2 below.

[0079] Table 1 - Explanation of Road Surface Adhesion State Switching Conditions

[0080] serial number condition A1 Satisfies: Vehicle low-mounted marker position = 1 A2 Satisfies: Vehicle height attached to marker position = 1 A3 Count = Count threshold 1 (first count threshold) A4 Satisfies: Vehicle height attached to marker position = 1 A5 Satisfies: Vehicle low-mounted marker position = 1 A6 Count = Count threshold 2 (second counting threshold)

[0081] Table 2 - Explanation of Road Surface Adhesion Status

[0082] Status Name Status output High-growth state The vehicle's display attachment status bit = 0; Low-adsorption state The vehicle's display attachment status bit = 1; Delay 1 The vehicle's display attachment status bit = 0; Delay 2 The vehicle's display attachment status bit = 1;

[0083] In the various embodiments described above, the current road adhesion state of the vehicle is determined to be either a first road adhesion state with higher adhesion or a second road adhesion state with lower adhesion, based on at least one of the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. Compared to the road adhesion coefficient estimated by existing dynamic methods, the embodiments of this application determine the current road adhesion state of the vehicle based on fundamental vehicle parameters such as longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio. Each road adhesion state corresponds to a wider range of road adhesion coefficients, thereby avoiding the problem of sudden changes in vehicle control due to large abrupt changes in the adhesion coefficient, and providing a stable and reliable reference index for distributing torque to the drive wheels.

[0084] In the embodiments described above, the road surface adhesion state of the vehicle is stably identified based on logical judgment using basic vehicle signals such as wheel slip ratio, longitudinal acceleration (measurable by an inertial measurement unit), lateral acceleration (measurable by an inertial measurement unit), vehicle speed, and net torque, for vehicle torque control. Compared with existing technologies, this method has the following advantages: 1) It uses logical judgment to determine the road surface adhesion state, resulting in robust road surface identification; 2) It only requires signals measured by conventional vehicle sensors for road surface adhesion determination, reducing implementation costs; 3) It eliminates the need for an electronic stability control system, enhancing feasibility.

[0085] In addition, this application embodiment also provides a road surface adhesion state determination device, which includes: a storage medium and a processor. The storage medium stores a computer program executed by the processor. When the computer program is executed by the processor, the processor performs any of the above-mentioned methods for determining the road surface adhesion state.

[0086] Figure 5 A schematic block diagram of a road surface adhesion state determination device 100 according to an embodiment of this application is shown. Figure 5 As shown, the road surface adhesion state determination device 100 according to an embodiment of this application may include a storage medium 110 and a processor 120. The storage medium 110 stores a computer program executed by the processor 120. When the computer program is executed by the processor 120, the processor 120 performs the road surface adhesion state determination method described above according to an embodiment of this application. Those skilled in the art can understand the specific operation of the road surface adhesion state determination device 100 deployment device according to the embodiments of this application in conjunction with the foregoing content; for the sake of brevity, it will not be described in detail here.

[0087] The storage medium 110 may include, for example, a memory card of a smartphone, a storage component of a tablet computer, a hard disk of a personal computer, a read-only memory (ROM), an erasable programmable read-only memory (EPROM), a portable compact disc read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. A computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0088] Furthermore, embodiments of this application also provide a vehicle controller, see reference. Figure 6 The vehicle controller 200 includes a road surface adhesion determination device 100. The vehicle controller 200 can determine a strategy for distributing drive torque to the vehicle's drive wheels based on the road surface adhesion determination device 100.

[0089] In addition, this application also provides a vehicle, as shown in the embodiments. Figure 7 The vehicle 300 includes a vehicle body 310 and any of the aforementioned vehicle controllers 200 mounted on the vehicle body 310. The vehicle body 310 may include, but is not limited to, a chassis, wheels, a passenger compartment, doors, a transmission, a drive motor, and an engine. For example, the vehicle body 310 may have four independently driven wheels, making it a four-wheel drive vehicle. This four-wheel drive vehicle can be an electric vehicle, a hybrid vehicle, or a gasoline-powered vehicle.

[0090] The present invention has been described through the above embodiments. However, it should be understood that the above embodiments are for illustrative purposes only and are not intended to limit the invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for determining the road surface adhesion state, characterized in that, include: The current road adhesion state of the vehicle is determined based on the vehicle's longitudinal acceleration, lateral acceleration, torque of each drive wheel, and slip ratio. If the torque and slip ratio of at least one drive wheel of the vehicle are in the second state, the longitudinal acceleration of the vehicle is less than or equal to the second longitudinal acceleration threshold, and the lateral acceleration of the vehicle satisfies the second lateral condition, then the vehicle is determined to be in the second road surface adhesion state. The road surface adhesion state includes at least a first road surface adhesion state and a second road surface adhesion state, wherein the minimum road surface adhesion coefficient corresponding to the first road surface adhesion state is greater than the maximum road surface adhesion coefficient corresponding to the second road surface adhesion state; the second state includes at least: the slip ratio of the drive wheel is less than or equal to a second slip ratio threshold, and the net torque of the drive wheel is less than or equal to a second threshold threshold; the second lateral condition includes: the actual lateral acceleration of the vehicle is less than or equal to a second actual threshold, and the ideal lateral acceleration of the vehicle is less than or equal to a second ideal threshold.

2. The determination method as described in claim 1, characterized in that, The first road surface adhesion state corresponds to the first road surface adhesion coefficient range, and the second road surface adhesion state corresponds to the second road surface adhesion coefficient range. Wherein, the minimum value of the first road surface adhesion coefficient range is greater than the maximum value of the second road surface adhesion coefficient range.

3. The determination method as described in claim 1, characterized in that, Determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, includes: The current road surface adhesion state of the vehicle is determined based on the torque and slip ratio of the vehicle's drive wheels; If the torque and slip ratio of all drive wheels of the vehicle are in the first state, then the vehicle is determined to be in the first road surface adhesion state. The first state includes at least the following: the slip ratio of the drive wheel is greater than or equal to a first slip ratio threshold, and the net torque of the drive wheel is greater than or equal to a first threshold threshold.

4. The determination method as described in claim 3, characterized in that, The first threshold is determined based on the load of the drive wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state.

5. The determination method as described in claim 3, characterized in that, The first state further includes at least the following: the net torque of the drive wheel is greater than or equal to a first set threshold.

6. The determination method as described in claim 1, characterized in that, Determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, includes: The current road surface adhesion state of the vehicle is determined based on the longitudinal acceleration of the vehicle's drive wheels; If the longitudinal acceleration of the vehicle is greater than or equal to the first longitudinal acceleration threshold, then the vehicle is determined to be in the first road surface adhesion state.

7. The determination method as described in claim 1, characterized in that, Determining the current road surface adhesion state of the vehicle based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, drive wheel torque, and slip ratio, includes: The current road surface adhesion state of the vehicle is determined based on the lateral acceleration of the vehicle's drive wheels; If the lateral acceleration of the vehicle satisfies the first lateral condition, then the vehicle is determined to be in the first road surface adhesion state.

8. The determination method as described in claim 7, characterized in that, The first lateral condition includes: the actual lateral acceleration of the vehicle is greater than or equal to a first actual threshold, and the ideal lateral acceleration of the vehicle is greater than or equal to a first ideal threshold.

9. The determination method as described in claim 1, characterized in that, The second threshold is determined based on the load of the drive wheel, the rolling radius, and the maximum road adhesion coefficient corresponding to the second road adhesion state.

10. The determination method as described in claim 1, characterized in that, The second state further includes at least the following: the net torque of the drive wheel is greater than or equal to a second set threshold.

11. The determination method as described in claim 1, characterized in that, Also includes: Obtain the vehicle speed; When the vehicle speed is greater than a speed threshold, the current road surface adhesion state of the vehicle is determined based on at least one of the following parameters: longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip ratio.

12. The determining method according to any one of claims 1 to 11, characterized in that, The determination method further includes: a method for determining the switching between the first road surface adhesion state and the second road surface adhesion state.

13. The determination method as described in claim 12, characterized in that, The method for determining the switching between the first road surface adhesion state and the second road surface adhesion state includes: When the vehicle's current road surface adhesion state is the first road surface adhesion state, and the vehicle is determined to be in the second road surface adhesion state at least twice consecutively, the vehicle's current road surface adhesion state is switched to the second road surface adhesion state; or, When the vehicle's current road surface adhesion state is the second road surface adhesion state, and the vehicle is determined to be in the first road surface adhesion state at least twice consecutively, the vehicle's current road surface adhesion state is switched to the first road surface adhesion state.

14. A device for determining the road surface adhesion state, characterized in that, include: A storage medium and a processor, wherein the storage medium stores a computer program executed by the processor, the computer program, when executed by the processor, causes the processor to perform the method for determining the road surface adhesion state as described in any one of claims 1 to 13.

15. A vehicle controller, characterized in that, include: The device for determining the road surface adhesion state as described in claim 14.

16. A vehicle, characterized in that, include: Vehicle body; The vehicle controller as described in claim 15 is mounted on the vehicle body.

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