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

Abstract

The invention discloses a method and a device for determining a road adhesion state, a vehicle control unit and a vehicle, and the method comprises the steps: determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration and lateral acceleration of the vehicle, and the torque and slip rate of a driving wheel; the road surface attachment state at least comprises a first road surface attachment state and a second road surface attachment state, and the minimum road surface attachment coefficient corresponding to the first road surface attachment state is larger than the maximum road surface attachment coefficient corresponding to the second road surface attachment state. According to the basic parameters of the vehicle, such as the longitudinal acceleration, the lateral acceleration, the torque of the driving wheel and the slip rate, the current road surface attachment state of the vehicle is determined, so that the problem of vehicle control sudden change caused by large sudden change of the utilization of the attachment coefficient can be avoided; the method can be stably and reliably used as a reference index for distributing torque to the driving wheel.

Description

Technical Field

[0001] The present application relates to the field of transportation vehicles, and more specifically to a method for determining a road surface adhesion state and a device thereof, a vehicle controller and a vehicle. Background Art

[0002] At present, the judgment of road adhesion is mostly based on the estimation of road adhesion coefficient, and the estimation method of road adhesion coefficient usually includes dynamic method. The road adhesion coefficient estimated by dynamic method is usually the utilization adhesion coefficient of wheel to road surface. During the estimation process, the utilization adhesion coefficient of wheel to road surface may have a large mutation problem due to interference factors such as but not limited to sudden increase of wheel speed and large axle load transfer, resulting in instability in the reference of road adhesion coefficient estimated by dynamic method. Summary of the invention

[0003] The present application is proposed to solve at least one of the above problems. According to the first aspect of the present application, a method for determining a road adhesion state is provided, the method comprising: determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle; wherein the road adhesion state at least includes a first road adhesion state and a second road adhesion state, and the minimum road adhesion coefficient corresponding to the first road adhesion state is greater than the maximum road adhesion coefficient corresponding to the second road adhesion state.

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

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

[0006] In one embodiment of the present application, the first threshold value is determined according to the load of the driving wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state.

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

[0008] In one embodiment of the present application, determining the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, drive wheel torque and slip rate includes: determining the current road adhesion state of the vehicle based on the longitudinal acceleration of the vehicle's drive wheels; and determining that the vehicle is in the first road 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 the present application, determining the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, driving wheel torque and slip rate includes: determining the current road adhesion state of the vehicle based on the lateral acceleration of the vehicle's driving wheels; and determining that the vehicle is in the first road adhesion state if the vehicle's lateral acceleration satisfies a first lateral condition.

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

[0011] In one embodiment of the present application, determining the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, torque of the driving wheels, and slip rate includes: determining the current road adhesion state of the vehicle based on the vehicle's longitudinal acceleration, lateral acceleration, torque of each driving wheel, and slip rate; if the torque and slip rate of at least one driving 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 determining that the vehicle is in the second road adhesion state; wherein the second state includes at least: the slip rate of the driving wheel is less than or equal to a second slip rate threshold, and the net of the driving wheel is less than or equal to a second threshold.

[0012] In one embodiment of the present application, the second threshold value is determined according to the load of the driving wheel, the rolling radius and the maximum road adhesion coefficient corresponding to the second road adhesion state.

[0013] In one embodiment of the present application, the second state also includes at least: the net torque of the driving wheel is greater than or equal to a second set threshold.

[0014] In one embodiment of the present 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 the present application, the determination method also includes: obtaining the vehicle speed of the vehicle; when the vehicle speed is greater than a speed threshold, determining the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, driving wheel torque and slip rate.

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

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

[0018] According to the second aspect of the present application, a device for determining the road adhesion state is also provided, and the determination device includes: a storage medium and a processor, and the storage medium stores a computer program run by the processor, and when the computer program is run by the processor, the processor executes any one of the above-mentioned methods for determining the road adhesion state.

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

[0020] According to a fourth aspect of the present application, a vehicle is also provided, comprising: a vehicle body, and any one of the above-mentioned vehicle controllers arranged on the vehicle body.

[0021] According to the road adhesion state determination method and device, vehicle controller and vehicle provided in the embodiment of the present application, the current road adhesion state of the vehicle is determined to be in a first road adhesion state with a higher adhesion state or a second road adhesion state with a lower adhesion state, such as but not limited to, based on at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. Compared with the road adhesion coefficient estimated by the existing dynamic method, the present application determines which road adhesion state the current road adhesion state of the vehicle is in based on the basic parameters of the vehicle, such as the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle, thereby avoiding the problem of sudden changes in vehicle control due to large sudden changes in the use of the adhesion coefficient, and can be used as a reference indicator for distributing torque to the driving wheel stably and reliably. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0023] Figure 1 A flow chart of a method for determining a road surface adhesion state according to an embodiment of the present invention;

[0024] Figure 2 This is a flow chart of a method for determining a road surface adhesion state according to another embodiment of the present invention;

[0025] Figure 3 This is a flow chart of a method for determining a road surface adhesion state according to another embodiment of the present invention;

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

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

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

[0029] Figure 7 A schematic block diagram of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention more obvious, the exemplary embodiments according to the present invention will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments of the present invention, and 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 in the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the protection scope of the present invention.

[0031] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present invention. However, it is apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present invention, some technical features well known in the art are not described.

[0032] It should be understood that the present invention can be implemented in different forms and should not be interpreted as limited to the embodiments set forth herein. On the contrary, these embodiments are provided to make the disclosure thorough and complete and to fully convey the scope of the present invention to those skilled in the art.

[0033] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, confirm the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0034] In order to fully understand the present invention, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present invention. The optional embodiments of the present invention are described in detail as follows, but in addition to these detailed descriptions, the present invention may also have other implementations.

[0035] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0036] First, the application scenario of the method for determining the road adhesion state illustrated in the example of the present application is introduced. The method for determining the road adhesion state is applied in the power control process of the vehicle, specifically, in the process of determining the current road adhesion state of the vehicle.

[0037] refer to Figure 1, an embodiment of the present application provides a method for determining a road adhesion state, the determination method comprising: determining a current road adhesion state of a vehicle according to at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, torque of a driving wheel, and slip rate; wherein the road adhesion state includes at least a first road adhesion state and a second road adhesion state, and a minimum road adhesion coefficient corresponding to the first road adhesion state is greater than a maximum road adhesion coefficient corresponding to the second road adhesion state.

[0038] In the above scheme, the current road adhesion state of the vehicle is determined to be in a first road adhesion state with a higher adhesion state or a second road adhesion state with a lower adhesion state, such as but not limited to, according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. Compared with the road adhesion coefficient estimated by the existing dynamic method, the embodiment of the present application determines which road adhesion state the current road adhesion state of the vehicle is in according to the basic parameters of the vehicle such as the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle, thereby avoiding the problem of sudden changes in vehicle control due to large sudden changes in the use of the adhesion coefficient, and can be used as a reference indicator for allocating torque to the driving wheel stably and reliably. The above steps are described in detail below in conjunction with the accompanying drawings.

[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 higher than the second road surface adhesion state. It should be explained that the road surface adhesion state here is pre-set, and there can be at least two road surface adhesion states. Exemplarily, the present application is explained below using two road surface adhesion states (respectively, the first road surface adhesion state and the second road surface adhesion state) as an example. It should be noted that the pre-set road surface adhesion state in the embodiment of the present application is not limited to two. In addition, it can also be any value of not less than three road surface adhesion states, such as three road surface adhesion states, four road surface adhesion states, etc.

[0040] Each road adhesion state corresponds to a different range of road adhesion coefficients. Some road adhesion states contain larger road adhesion coefficients, while some road adhesion states contain smaller road adhesion coefficients. In the following example, the minimum road adhesion coefficient corresponding to the first road adhesion state is higher than the maximum road adhesion coefficient corresponding to the second road adhesion state. For example, Figure 3-4 The high adhesion or high adhesion state in refers to the first road adhesion state, such as Figure 3-4 The low adhesion or low adhesion state refers to the second road adhesion state.

[0041] Exemplarily, the road adhesion coefficient corresponding to each road adhesion state may be a specific value, in which case the minimum road adhesion coefficient and the maximum road adhesion coefficient corresponding to each road adhesion state are both fixed values. In other embodiments, the road adhesion coefficient corresponding to each road adhesion state may correspond to a road adhesion coefficient range. For example, the first road adhesion state may correspond to a first road adhesion coefficient range, and the second road adhesion state may correspond to a second road adhesion coefficient range, wherein the minimum value of the first road adhesion coefficient range is greater than the maximum value of the second road adhesion coefficient range. Not only is it ensured that the minimum road adhesion coefficient of the first road adhesion state is greater than the maximum road adhesion coefficient of the second road adhesion state, but each road adhesion state also corresponds to a wider road adhesion coefficient range, preventing the road adhesion state from switching too many times.

[0042] The driving wheels of a vehicle refer to wheels that can provide driving torque to the vehicle. The method for determining the road adhesion state shown in the embodiment of the present application can be applied to independent four-wheel drive vehicles, that is, the vehicle is provided with four independently driven driving wheels. Each driving wheel can provide driving torque through a driving motor or an engine. That is, the method for determining the road adhesion state shown in the embodiment of the present application can be applied to, for example, but not limited to, electric vehicles, hybrid vehicles, or fuel vehicles.

[0043] When determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle, a variety of methods can be combined. Exemplarily, the current road adhesion state of the vehicle can be determined based on only one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. For example, it can be determined whether the vehicle is currently in the first road adhesion state only based on the longitudinal acceleration or lateral acceleration of the vehicle. The current road adhesion state of the vehicle can also be determined based on only two parameters of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. For example, it can be determined whether the vehicle is currently in the first road adhesion state only based on the torque and slip rate of the driving wheel of the vehicle. At present, the current road adhesion state of the vehicle can also be determined based on any three parameters or all parameters of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. That is, in the embodiments of the present application, as long as it is possible to determine whether the vehicle is currently in a certain road adhesion state or not based on at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel, and slip rate of the vehicle, it is within the protection scope of the embodiments of the present application. Several determination methods are exemplarily introduced below.

[0044] Exemplary, reference Figure 2, determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque and slip rate of the driving wheel of the vehicle may include: determining the current road adhesion state of the vehicle according to the torque and slip rate of the driving wheel of the vehicle. If the torque and slip rate of all driving wheels of the vehicle are in the first state, it is determined that the vehicle is in the first road adhesion state. Among them, the first state may at least include: the slip rate of the driving wheel is greater than or equal to the first slip rate threshold, and the net torque of the driving wheel is greater than or equal to the first threshold. That is, the slip rate of the driving wheel is a high slip rate, and the net torque of the driving wheel is a large torque.

[0045] For example, when four drive wheels are provided on the vehicle, when the net torque and slip ratio of the four drive wheels on the vehicle are in the first state, it can be directly determined that the vehicle is in the first road adhesion state. Among them, the slip ratio of the drive wheel is determined based on the wheel speed and vehicle speed of the drive wheel. Specifically, the slip ratio can be calculated as (wheel speed-vehicle speed) / wheel speed*100%. In a more optimal way, the wheel speed can be divided by zero protection. Among them, the net torque of the drive wheel refers to the drive torque output by the motor or engine to the drive road minus the hydraulic wheel end torque of the drive wheel, that is, the net torque of the drive wheel is equal to the drive torque of the drive wheel minus the braking torque. It should be understood that the method of determining whether the first state is satisfied based on the torque of the drive wheel of the vehicle is not limited to using the net torque of the drive wheel. In addition, 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] When determining the first threshold value, it can be determined in a variety of ways, which are related to the current load of the driving wheel and the minimum road adhesion coefficient corresponding to the preset first road adhesion state. Exemplarily, the first threshold value can be determined based on the load of the driving wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state. Exemplarily, the first threshold value can be the absolute value of the product of the vertical load of the driving wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state. It should be noted that the minimum road adhesion coefficient corresponding to the above-mentioned first road adhesion state is a calibration quantity, which is a parameter determined in advance by testing, simulation, etc. The minimum road adhesion coefficient corresponding to the first road adhesion state can be: the minimum value in the first road adhesion coefficient range corresponding to the first road adhesion state. Of course, in other embodiments, the first threshold value can also be determined based on the first road adhesion state of the driving wheel and other parameters of the vehicle.

[0047] Exemplarily, the first state mentioned above may also include: the slip rate of the driving wheel is greater than or equal to the first slip rate threshold. The first set threshold is a calibration value pre-set by methods such as but not limited to testing, simulation, etc. The reason for setting the first set threshold is that the first set threshold is not affected by the load during the operation of the vehicle. Only when the net torque of the driving wheel is greater than the first set threshold can the judgment process of whether it belongs to a large torque be triggered, thereby improving the accuracy of the judgment of the large torque. When all the driving wheels of the vehicle are in the first state of high slip rate and large torque, it is determined that the entire vehicle is in the first road adhesion state.

[0048] like Figure 2 As shown, when determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle, the current road adhesion state of the vehicle can be determined according to the longitudinal acceleration of the driving wheel of the vehicle. If the longitudinal acceleration of the vehicle is greater than or equal to the first longitudinal acceleration threshold, it can be determined that the vehicle is in the first road adhesion state. That is, the current longitudinal acceleration of the vehicle is relatively large, because only when the vehicle is in a higher road adhesion state can the vehicle output a relatively large longitudinal acceleration. That is, one of the necessary conditions for the vehicle to output a relatively large longitudinal acceleration is that the vehicle is in a relatively high road adhesion state. Then, when the longitudinal acceleration of the vehicle is greater than or equal to the first longitudinal acceleration threshold, it can be directly determined that the vehicle is in the first road adhesion state.

[0049] like Figure 2 As shown, when determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of each driving wheel and slip rate of the vehicle, the current road adhesion state of the vehicle can be determined according to the lateral acceleration of the driving wheel of the vehicle. If the lateral acceleration of the vehicle satisfies the first lateral condition, it can be determined that the vehicle is in the first road adhesion state. That is, the current lateral acceleration of the vehicle is relatively large, because only when the vehicle is in a higher road adhesion state can the vehicle output a relatively large lateral acceleration. That is, one of the necessary conditions for the vehicle to output a relatively large lateral acceleration is that the vehicle is in a relatively high road adhesion state. Then, when the lateral acceleration of the vehicle is greater than or equal to the first longitudinal acceleration threshold, it can be directly determined that the vehicle is in the first road adhesion state.

[0050] When determining the first lateral condition, it is related to the actual lateral acceleration and the ideal lateral acceleration of the vehicle. Exemplarily, the first lateral condition may include: the actual lateral acceleration of the vehicle is greater than or equal to the first actual threshold, and the ideal lateral acceleration of the vehicle is greater than or equal to the first ideal threshold. That is, if the actual lateral acceleration of the vehicle is large, the ideal lateral acceleration of the vehicle is also large. Among them, the actual lateral acceleration of the vehicle can be determined according to the operating state of the vehicle, and the ideal lateral acceleration of the vehicle can be determined according to the turning angle of the steering wheel of the vehicle. It should be understood that the setting method of the first lateral condition is not limited to the method shown above, and other methods can also be used in addition to this. For example, it is also possible to only use the actual lateral acceleration of the vehicle and the actual threshold to judge, without judging the ideal lateral acceleration and the ideal threshold.

[0051] like Figure 2 As shown, the current road adhesion state of the vehicle is determined according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque and slip rate of the driving wheel of the vehicle, and it can also include: determining the current road adhesion state of the vehicle according to the longitudinal acceleration, lateral acceleration, torque and slip rate of each driving wheel of the vehicle. If the torque and slip rate of at least one driving 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 meets the second lateral condition, it is determined that the vehicle is in the second road adhesion state. Among them, the second state can at least include: the slip rate of the driving wheel is less than or equal to the second slip rate threshold, and the net torque of the driving wheel is less than or equal to the second threshold. That is, when the driving wheel is in the second state, the slip rate of the driving wheel belongs to a low slip rate, and the net torque of the driving wheel belongs to a small torque.

[0052] That is, as long as the net torque and slip ratio of at least one driving wheel of the vehicle are in the second state (specifically, the net torque and slip ratio of one, two, three or four driving wheels of the vehicle are in the second state), the longitudinal acceleration of the vehicle is small, and the lateral acceleration of the vehicle satisfies the smaller second lateral condition, it can be determined that the vehicle is in the second road adhesion state. Otherwise, the current displayed adhesion state of the vehicle is kept unchanged. It should be explained that the displayed adhesion state of the vehicle refers to the road adhesion state currently displayed by the vehicle to the outside, which can be the road adhesion state input to the vehicle controller as a reference for torque distribution, which can be the above-mentioned first road adhesion state, or the second road adhesion state. When the vehicle controller distributes torque to each driving wheel, it needs to ensure that the utilized adhesion coefficient of each driving wheel is not greater than the maximum road adhesion coefficient corresponding to the current displayed adhesion state of the vehicle. It should be explained that the utilized adhesion coefficient refers to: the degree of utilization of the road adhesion coefficient by the wheel-end driving force of the current driving wheel. Reference Figure 3 and Figure 4, at the beginning, it can be defaulted to the first road adhesion state, that is, the high adhesion state. It should be understood that the method of determining whether the second state is satisfied based on the torque of the driving wheel of the vehicle is not limited to using the net torque of the driving wheel. In addition, other methods can also be used. For example, torque parameters such as actual torque can also be used as a method for determining whether the second state is satisfied.

[0053] It should be noted that the second slip rate threshold and the first slip rate threshold are both calibrated quantities, that is, parameters that are determined in advance through testing, simulation, etc. The first slip rate threshold is greater than the second slip rate threshold. That is, when the driving wheel is in the second state, its slip rate is a low slip rate.

[0054] When determining the second threshold value, it can be determined in a variety of ways, which are related to the current load of the driving wheel and the maximum road adhesion coefficient corresponding to the preset second road adhesion state. Exemplarily, the second threshold value can be determined based on the load of the driving wheel, the rolling radius and the maximum road adhesion coefficient corresponding to the second road adhesion state. Exemplarily, the second threshold value can be the absolute value of the product of the vertical load of the driving wheel, the 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 above-mentioned second road adhesion state is a calibration quantity, which is a parameter determined in advance by testing, simulation, etc. The maximum road adhesion coefficient corresponding to the second road adhesion state can be: the maximum value of the second road adhesion coefficient range corresponding to the second road adhesion state. Of course, in other embodiments, the second threshold value can also be determined based on the second road adhesion state of the driving wheel and other parameters of the vehicle.

[0055] Exemplarily, the above-mentioned second state may also include at least: the net torque of the driving wheel is greater than or equal to the second set threshold. The second set threshold is a calibration quantity pre-set by methods such as but not limited to testing, simulation, etc. The reason for setting the second set threshold is that the second set threshold is not affected by the load and speed during the operation of the vehicle. Only when the net torque of the driving wheel is greater than the second set threshold, can the judgment process of whether it belongs to a large torque be triggered to prevent the net torque from being too small and the speed from being too low, resulting in a large error in judging a small torque, thereby improving the accuracy of judging a small torque. When at least one driving wheel of the vehicle is in the second state of low slip and small torque, it is determined that the vehicle is in the second road adhesion state. It should be noted that the second set threshold and the first set threshold are both calibration quantities, that is, parameters pre-determined by testing, simulation, etc. The second set threshold is to be less than the first set threshold.

[0056] When determining the above-mentioned second lateral condition, a variety of methods can be used. Exemplarily, the second lateral condition may include: the actual lateral acceleration of the vehicle is less than or equal to the second actual threshold, and the ideal lateral acceleration of the vehicle is less than or equal to the 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 quantities, which are parameters determined in advance through testing, simulation and the like. Among them, 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 lateral acceleration of the vehicle when the first lateral condition is met is greater than the lateral acceleration when the second lateral condition is met. It should be understood that the setting method of the second lateral condition is not limited to the method shown above, and other methods can also be used in addition. For example, it is also possible to only use the actual lateral acceleration of the vehicle and the actual threshold for judgment, without judging the ideal lateral acceleration and the ideal threshold.

[0057] In a more preferred embodiment, the determination method may further include: obtaining the speed of the vehicle; when the speed of the vehicle is greater than a speed threshold, determining the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip rate. That is, only when the vehicle's speed is relatively high, the above method is used to determine the current road adhesion state of the vehicle based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip rate. If the vehicle's speed does not exceed the speed threshold, the above method is not used, and the current road adhesion state of the vehicle is determined based on at least one parameter of the vehicle's longitudinal acceleration, lateral acceleration, torque of the drive wheels, and slip rate. This prevents the defect of inaccurate road adhesion state determined by the above method due to the vehicle's speed being too low, thereby improving the accuracy of the road adhesion state determination. Figure 3 As shown, when the vehicle speed is greater than the speed threshold, the vehicle is in a driving state. Otherwise, the current displayed attachment state of the vehicle is kept unchanged.

[0058] In some embodiments, the determination method may further include: determining the displayed adhesion state of the vehicle based on the determined current road adhesion state of the vehicle. That is, after each determination of the current road adhesion state of the vehicle, determine whether to change the displayed adhesion state of the vehicle. It should be explained that the displayed adhesion state of the vehicle refers to the road adhesion state that the vehicle currently displays to the outside, which can be the road adhesion state input to the vehicle controller as a reference for torque distribution, which can be the above-mentioned first road adhesion state, or the second road adhesion state. When the vehicle controller distributes torque to each drive wheel, it needs to ensure that the utilized adhesion coefficient of each drive wheel is not greater than the maximum road adhesion coefficient corresponding to the current displayed adhesion state of the vehicle. It should be explained that the utilized adhesion coefficient refers to: the degree of utilization of the road adhesion coefficient by the wheel-end driving force of the current drive wheel. Reference Figure 3 and Figure 4 , initially, it can default to the first road adhesion state, that is, the high adhesion state.

[0059] In some embodiments, the determination method may also include optimizing the switching condition of the current road adhesion state of the vehicle from one road adhesion state to another road adhesion state. Exemplarily, the determination method may also include: a switching determination method for the first road adhesion state and the second road adhesion state. When switching between the first road adhesion state and the second road adhesion state, the current road adhesion state of the vehicle may be determined based on the road adhesion state of the vehicle determined at least once. Specifically, the current road adhesion state of the vehicle may be determined based on the road adhesion state of the vehicle determined once, twice, three times, or any other one or more times.

[0060] Exemplarily, the method for determining the switch between the first road adhesion state and the second road adhesion state may include: when the current road adhesion state of the vehicle is the first road adhesion state, the current road adhesion state of the vehicle is switched to the second road adhesion state only when it is determined that the vehicle is in the second road adhesion state at least twice in a row. Specifically, a first counting threshold may be set, and the first counting threshold may be any value greater than 2. When the current road adhesion state of the vehicle is the first road adhesion state, only when it is determined that the vehicle is in the second road adhesion state for consecutive first counting threshold times, the current road adhesion state of the vehicle is switched from the first road adhesion state to the second road adhesion state. Otherwise, the current road adhesion state of the vehicle remains unchanged in the current first road adhesion state. The current road adhesion state of the vehicle is prevented from being switched too frequently, so as to maintain a stable and reliable reference indicator for distributing torque to the drive wheels.

[0061] In another embodiment, the method for determining the switch between the first road adhesion state and the second road adhesion state may further include: when the current road adhesion state of the vehicle is the second road adhesion state, the current road adhesion state of the vehicle is switched to the first road adhesion state only when it is determined that the vehicle is in the first road adhesion state at least twice in a row. Specifically, a second counting threshold may be set, and the second counting threshold may be any value greater than 2. When the current road adhesion state of the vehicle is the second road adhesion state, only when it is determined that the vehicle is in the first road adhesion state for consecutive second counting threshold times, the current road adhesion state of the vehicle is switched from the second road adhesion state to the first road adhesion state. Otherwise, the current road adhesion state of the vehicle remains unchanged at the current second road adhesion state. The current road adhesion state of the vehicle is prevented from being switched too frequently, so as to maintain a stable and reliable reference indicator for distributing torque to the drive wheels.

[0062] The current road adhesion state of the vehicle can be the displayed adhesion state currently output and displayed by the vehicle, which is used as a reference indicator for allocating torque to the driving wheel. Corresponding to the current road adhesion state of the vehicle determined above, in some embodiments, the determination method may also include optimizing the switching conditions for switching the displayed adhesion state of the vehicle from one road adhesion state to another road adhesion state. Exemplarily, the determination method may also include: when the displayed adhesion state of the vehicle is the first road adhesion state, if it is determined that the vehicle is in the second road adhesion state at least twice in a row, the displayed adhesion state of the vehicle is switched to the second road adhesion state. Specifically, a first counting threshold can be set, and the first counting threshold can be any value greater than 2. When the displayed adhesion state of the vehicle is the first road adhesion state, only when the first counting threshold number of times in a row determines that the vehicle is in the second road adhesion state, it is determined that the displayed adhesion state of the vehicle is switched from the first road adhesion state to the second road adhesion state. Otherwise, the displayed adhesion state of the vehicle remains unchanged in the current first road adhesion state. Prevent the displayed adhesion state from being switched too frequently to maintain a stable and reliable reference indicator for allocating torque to the driving wheel.

[0063] In other embodiments, the determination method may further include: when the displayed adhesion state of the vehicle is the second road adhesion state, the displayed adhesion state of the vehicle is switched to the first road adhesion state only when it is determined that the vehicle is in the first road adhesion state at least twice in a row. Specifically, a second counting threshold may be set, and the second counting threshold may be any value greater than 2. When the displayed adhesion state of the vehicle is the second road adhesion state, the displayed adhesion state of the vehicle is switched from the second road adhesion state to the first road adhesion state only when it is determined that the vehicle is in the first road adhesion state for consecutive second counting threshold times. Otherwise, the displayed adhesion state of the vehicle remains unchanged at the current second road adhesion state. The displayed adhesion state is prevented from being switched too frequently to maintain a stable and reliable reference indicator for allocating torque to the drive wheels.

[0064] The following is combined with Figure 3-4 , as an example, a specific application method is introduced. The road adhesion recognition method applicable to four-wheel independent drive mainly judges the current road adhesion state (high adhesion / low adhesion) of the vehicle through four aspects: the actual wheel end torque of the driving wheel, the vehicle speed, the slip rate, and the vehicle acceleration. The overall idea of ​​the recognition method is as follows:

[0065] (1) Vehicle low adhesion judgment: Taking the left front wheel as an example, if the net torque of the left front wheel is small and the left front wheel has a high slip rate, the left front wheel is judged 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 a driving state, one of the four wheels is in the second state and the longitudinal acceleration and lateral acceleration of the vehicle are both small, then the current road adhesion state of the vehicle is determined to be a low adhesion state.

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

[0067] Among them, the judgment method of the large torque, small torque, high slip rate, low slip rate, large longitudinal acceleration, small longitudinal acceleration, large lateral acceleration, small lateral acceleration and the driving state of the vehicle at the above wheel ends is as follows.

[0068] 1) Wheel end slip rate high and low flag judgment. Taking the left front wheel as an example (the situation of other wheels is the same and will not be repeated), if the left front wheel slip rate is greater than or equal to threshold 1 (the first slip rate threshold), the left front wheel is judged as a high slip rate; if the left front wheel slip rate is less than or equal to threshold 2 (the second slip rate threshold), the left front wheel is judged as a low slip rate; wherein, threshold 1 and threshold 2 are both calibrated quantities, which are determined in advance by methods such as but not limited to testing, simulation, etc.

[0069] 2) When judging the torque size flag of the current wheel end. Taking the left front wheel as an example (the situation of other wheels is the same and will not be repeated), if the net torque of the left front wheel is greater than or equal to threshold 3 (the first set threshold), and the net torque of the left front wheel is greater than or equal to threshold 4 (the first threshold), the left front wheel is judged to have a large torque; if the net torque of the left front wheel is greater than or equal to threshold 5 (the second set threshold), and the net torque of the left front wheel is less than or equal to threshold 6 (the second threshold), the left front wheel is judged to have a small torque.

[0070] Among them, the net torque of the left front wheel = the wheel end torque of the left front wheel motor - the wheel end torque of the left front wheel hydraulic pressure;

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

[0074] 3) Determine the current state of vehicle acceleration.

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

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

[0077] 4) Vehicle driving judgment: If |vehicle speed|>threshold 13 (vehicle speed threshold), it is judged that the vehicle is in a driving state.

[0078] 5) Road adhesion state switching. Figure 4 The vehicle's displayed adhesion state takes high adhesion as the default adhesion state, and the road adhesion state switching is completed according to the conditions shown in Table 1 and Table 2 below.

[0079] Table 1- Description of road adhesion state switching conditions

[0080] serial number condition A1 Satisfy: Vehicle low attachment flag = 1 A2 Satisfy: Vehicle high attachment flag = 1 A3 Count = Count Threshold 1 (First Count Threshold) A4 Satisfy: Vehicle high attachment flag = 1 A5 Satisfy: Vehicle low attachment flag = 1 A6 Count = count threshold 2 (second count threshold)

[0081] Table 2-Road Adhesion Status Bit Description

[0082] Status Name Status Output High Attachment State The display attachment status of the vehicle = 0; Low adhesion state The display attachment status bit of the vehicle = 1; Delay 1 The display attachment status of the vehicle = 0; Delay 2 The display attachment status bit of the vehicle = 1;

[0083] In the various embodiments shown above, the current road adhesion state of the vehicle is determined to be in a first road adhesion state with a higher adhesion state or a second road adhesion state with a lower adhesion state, such as but not limited to, based on at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. Compared with the road adhesion coefficient estimated by the existing dynamic method, the embodiment of the present application determines which road adhesion state the current road adhesion state of the vehicle is in based on the basic parameters of the vehicle such as the longitudinal acceleration, lateral acceleration, torque of the driving wheel and slip rate of the vehicle. 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 sudden changes in the use of the adhesion coefficient, and can be used as a reference indicator for distributing torque to the driving wheels stably and reliably.

[0084] In the above embodiments of the present application, the basic vehicle signals such as wheel slip rate, longitudinal acceleration (which can be measured by an inertial measurement unit), lateral acceleration (which can be measured by an inertial measurement unit), vehicle speed, net torque, etc. are used to stably identify the road adhesion state of the vehicle based on logical judgment for vehicle torque control. Compared with the prior art, it has the following advantages: 1) The road surface high and low adhesion state is judged based on logical judgment, and the road surface recognition result is more robust; 2) Only the signals measured by the conventional sensors of the vehicle are needed to judge the road adhesion, and the implementation cost is low; 3) There is no need to equip the vehicle electronic stability system, which enhances the feasibility of implementation.

[0085] In addition, an embodiment of the present application also provides a device for determining a road surface adhesion state, the device comprising: a storage medium and a processor, the storage medium storing a computer program run by the processor, and when the computer program is run by the processor, the processor executes any one of the above-mentioned methods for determining a road surface adhesion state.

[0086] Figure 5 FIG. 1 is a schematic block diagram of a device 100 for determining a road surface adhesion state according to an embodiment of the present application. Figure 5 As shown, the apparatus 100 for determining the road surface adhesion state according to the embodiment of the present 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 executes the method for determining the road surface adhesion state according to the embodiment of the present application described above. Those skilled in the art can understand the specific operation of the apparatus 100 for determining the road surface adhesion state according to the embodiment of the present application in combination with the above content, and for the sake of brevity, it will not be repeated here.

[0087] The storage medium 110 may include, for example, a memory card of a smart phone, 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 disk read-only memory (CD-ROM), a USB memory, or any combination of the above storage media. The computer-readable storage medium may be any combination of one or more computer-readable storage media.

[0088] Furthermore, the present application embodiment also provides a vehicle controller, referring to Figure 6 The vehicle controller 200 includes: any one of the road adhesion state determination devices 100. The vehicle controller 200 can determine a strategy for allocating driving torque to the driving wheels of the vehicle according to the road adhesion state determined by the road adhesion state determination device 100.

[0089] In addition, the present application embodiment also provides a vehicle, referring to Figure 7 The vehicle 300 includes: a vehicle body 310, and any of the above-mentioned vehicle controllers 200 disposed on the vehicle body 310. The vehicle body 310 may be provided with components such as, but not limited to, a chassis, wheels, a compartment, doors, a gearbox, a drive motor, an engine, etc. Exemplarily, four independently driven drive wheels are disposed on the vehicle body 310, that is, the vehicle at this time is an independent four-wheel drive vehicle. The independent four-wheel drive vehicle may specifically be an electric vehicle, a hybrid vehicle, a fuel vehicle, or other types of vehicles.

[0090] The present invention has been described by the above embodiments, but it should be understood that the above embodiments are only for the purpose of example and description, and are not intended to limit the present invention to the scope of the described embodiments. In addition, it can be understood by those skilled in the art that the present invention is not limited to the above embodiments, and more variations and modifications can be made according to the teachings of the present invention, and these variations and modifications all fall within the scope of the protection claimed by the present invention. The protection scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for determining road surface adhesion state, characterized in that: include: Determining a current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheels, and slip rate of the vehicle; The road surface adhesion state includes at least a first road surface adhesion state and a second road surface adhesion state, and a minimum road surface adhesion coefficient corresponding to the first road surface adhesion state is greater than a maximum road surface adhesion coefficient corresponding to the second road surface adhesion state.

2. The determination method according to claim 1, characterized in that: 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; The minimum value of the first road adhesion coefficient range is greater than the maximum value of the second road adhesion coefficient range.

3. The determination method according to claim 1, characterized in that: Determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel, and slip rate of the vehicle includes: Determining a current road adhesion state of the vehicle according to the torque and slip rate of the driving wheels of the vehicle; If the torque and slip ratio of all driving wheels of the vehicle are in the first state, determining that the vehicle is in the first road adhesion state; The first state at least includes: the slip rate of the driving wheel is greater than or equal to a first slip rate threshold, and the net torque of the driving wheel is greater than or equal to a first threshold.

4. The determination method according to claim 3, characterized in that: The first threshold value is determined according to the load of the driving wheel, the rolling radius, and the minimum road adhesion coefficient corresponding to the first road adhesion state.

5. The determination method according to claim 3, characterized in that: The first state also includes at least: the net torque of the driving wheel is greater than or equal to a first set threshold.

6. The determination method according to claim 1, characterized in that: Determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel, and slip rate of the vehicle includes: Determining a current road adhesion state of the vehicle according to a longitudinal acceleration of a driving wheel of the vehicle; If the longitudinal acceleration of the vehicle is greater than or equal to a first longitudinal acceleration threshold, it is determined that the vehicle is in the first road adhesion state.

7. The determination method according to claim 1, characterized in that: Determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel, and slip rate of the vehicle includes: determining a current road adhesion state of the vehicle according to a lateral acceleration of a driving wheel of the vehicle; If the lateral acceleration of the vehicle satisfies a first lateral condition, it is determined that the vehicle is in the first road adhesion state.

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

9. The determination method according to claim 1, characterized in that: Determining the current road adhesion state of the vehicle according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheel, and slip rate of the vehicle includes: Determining a current road adhesion state of the vehicle based on the longitudinal acceleration, lateral acceleration, torque of each driving wheel and slip rate of the vehicle; If the torque and slip ratio of at least one driving wheel of the vehicle are in the 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 it is determined that the vehicle is in the second road adhesion state; The second state at least includes: the slip rate of the driving wheel is less than or equal to a second slip rate threshold, and the net torque of the driving wheel is less than or equal to a second threshold.

10. The determination method according to claim 9, characterized in that: The second threshold value is determined according to the load of the driving wheel, the rolling radius and the maximum road adhesion coefficient corresponding to the second road adhesion state.

11. The determination method according to claim 9, characterized in that: The second state also includes at least: the net torque of the driving wheel is greater than or equal to a second set threshold.

12. The determination method according to claim 9, characterized in that: The second lateral condition includes: an actual lateral acceleration of the vehicle is less than or equal to a second actual threshold, and an ideal lateral acceleration of the vehicle is less than or equal to a second ideal threshold.

13. The determination method according to claim 1, characterized in that: Also includes: Obtaining the speed of the vehicle; When the vehicle speed is greater than a vehicle speed threshold, the current road adhesion state of the vehicle is determined according to at least one parameter of the longitudinal acceleration, lateral acceleration, torque of the driving wheels and slip rate of the vehicle.

14. The determination method according to any one of claims 1 to 13, characterized in that: The determination method further includes: a method for determining switching between a first road surface adhesion state and a second road surface adhesion state.

15. The determination method according to claim 14, 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 current road adhesion state of the vehicle is the first road adhesion state, when it is determined that the vehicle is in the second road adhesion state at least twice in succession, switching the current road adhesion state of the vehicle to the second road adhesion state; or, When the current road adhesion state of the vehicle is the second road adhesion state, when it is determined at least twice in succession that the vehicle is in the first road adhesion state, the current road adhesion state of the vehicle is switched to the first road adhesion state.

16. A device for determining 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, and when the computer program is executed by the processor, the processor executes the method for determining the road surface adhesion state as described in any one of claims 1 to 15.

17. A vehicle controller, characterized in that: include: The device for determining the road surface adhesion state as claimed in claim 16.

18. A vehicle, characterized in that: include: Vehicle body; The vehicle controller as claimed in claim 17 is arranged on the vehicle body.

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