CN114954029A

CN114954029A - Drive control method and device for four-wheel drive vehicle, and storage medium

Info

Publication number: CN114954029A
Application number: CN202110981654.7A
Authority: CN
Inventors: 周秉福
Original assignee: Great Wall Motor Co Ltd
Current assignee: Great Wall Motor Co Ltd
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2022-08-30

Abstract

The application provides a drive control method and device for a four-wheel drive vehicle, the vehicle and a storage medium. The method comprises the following steps: if the driving wheel slips under the driving working condition, acquiring the actual adhesion coefficient of the road surface where the slipping driving wheel is located; acquiring a vertical load of a slipping driving wheel; calculating an actual anti-skid torque of the slipping drive wheel based on the actual adhesion coefficient and the vertical load; sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for indicating the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque; and if the slipping driving wheel is not recovered to be normal, sending a braking request to a braking mechanism corresponding to the slipping driving wheel, wherein the braking request is used for indicating the braking mechanism to reduce the rotating speed of the slipping driving wheel. This application can control the drive wheel that skids and resume normally, promotes the stability of vehicle, reduces the vehicle and controls the risk.

Description

Drive control method and device for four-wheel drive vehicle, and storage medium

Technical Field

The present disclosure relates to the field of vehicle drive control technologies, and in particular, to a drive control method and apparatus for a four-wheel drive vehicle, a vehicle, and a storage medium.

Background

At present, when a vehicle is under a driving working condition, for example, when the vehicle starts or accelerates, wheel slip may occur due to different adhesion coefficients of different road surfaces, and when the vehicle starts or accelerates too fast, the wheel slip is particularly easy to occur, so that the stability of the vehicle is affected, and the control risk of the vehicle is increased.

With the development of the electric drive system technology and cost optimization, the power and the peak torque of the electric drive system are improved qualitatively. The vehicle acceleration performance of the user is improved, and meanwhile the problem that the vehicle is easy to slip in the starting process of a large acceleration pedal is also brought. This problem is particularly apparent for four-wheel drive vehicles.

Disclosure of Invention

The application provides a drive control method and device of a four-wheel drive vehicle, the vehicle and a storage medium, which are used for solving the problem that the stability of the vehicle is influenced by wheel slip when the vehicle starts or accelerates.

In a first aspect, the present application provides a drive control method of a four-wheel drive vehicle, comprising:

if the driving wheel slips under the driving working condition, acquiring the actual adhesion coefficient of the road surface where the slipping driving wheel is located;

acquiring a vertical load of a slipping driving wheel;

calculating an actual slip torque of the slipping drive wheel based on the actual adhesion coefficient and the vertical load;

sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for indicating the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque;

and if the slipping driving wheels are not recovered to be normal, sending a braking request to a braking mechanism corresponding to the slipping driving wheels, wherein the braking request is used for indicating the braking mechanism to reduce the rotating speed of the slipping driving wheels.

In one possible implementation, after sending a torque reduction request to the drive motor corresponding to the slipping drive wheel, the method further includes:

acquiring actual output torque of a slipping driving wheel;

calculating the difference between the actual output torque and the actual anti-skid torque to obtain an anti-skid braking torque;

accordingly, the braking request is used to instruct the braking mechanism to provide the anti-skid braking torque to the slipping drive wheels to reduce the rotational speed of the slipping drive wheels.

In one possible implementation manner, if the driving wheel slips under the driving condition, the obtaining of the actual adhesion coefficient of the road surface where the slipping driving wheel is located includes:

if the driving wheel slips under the driving working condition, calculating the slip rate of the slipping driving wheel;

acquiring the road surface type of a road surface where a slipping driving wheel is located;

searching a driving adhesion coefficient corresponding to the slip rate and the road surface type of the road surface where the slipping driving wheel is located from a preset second comparison table, and taking the driving adhesion coefficient as an actual adhesion coefficient of the road surface where the slipping driving wheel is located;

the second comparison table stores corresponding relations among various different road surface types, slip ratios and driving adhesion coefficients.

In a possible implementation manner, before the obtaining, if the driving wheel slips under the driving condition, an actual adhesion coefficient of a road surface on which the slipping driving wheel is located, the method further includes:

acquiring an ideal adhesion coefficient of a road surface to be driven;

acquiring a vertical load of a driving wheel;

and calculating ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and the vertical load of the driving wheel, and setting the ideal anti-skid torque as the maximum output torque of the driving motor corresponding to the driving wheel.

In one possible implementation, the calculating a desired anti-skid torque of the driving wheel based on the desired adhesion coefficient and a vertical load of the driving wheel, and setting the desired anti-skid torque as a maximum output torque of the driving wheel corresponding to the driving motor includes:

calculating an ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and a vertical load of the driving wheel;

correcting the ideal anti-skid torque according to a preset front and rear wheel torque distribution strategy to obtain an ideal anti-skid torque of the front wheel and an ideal anti-skid torque of the rear wheel;

under the working condition of ramp driving, setting the ideal anti-skid torque of the front wheel as the maximum output torque of the driving motor corresponding to the front driving wheel, and setting the ideal anti-skid torque of the rear wheel as the maximum output torque of the driving motor corresponding to the rear driving wheel;

if the vehicle is in an uphill working condition, the ideal anti-skid torque of the rear wheels is larger than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheels is smaller than the ideal anti-skid torque; and if the vehicle is in a downhill working condition, the ideal anti-skid torque of the rear wheels is smaller than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheels is larger than the ideal anti-skid torque.

In one possible implementation, after the calculating the ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and the vertical load of the driving wheel, the method further comprises:

if the slipping driving wheel is a front driving wheel, calculating the difference between the actual anti-slipping torque and the ideal anti-slipping torque of the front wheel to be used as a rear wheel correction torque; sending a torque increasing request to a driving motor corresponding to a rear driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal anti-skid torque of the rear wheel and the rear wheel correcting torque;

if the slipping driving wheel is a rear driving wheel, calculating the difference between the actual anti-slipping torque and the ideal anti-slipping torque of the rear wheel to be used as the correction torque of the front wheel; and sending a torque increasing request to a driving motor corresponding to the front driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal anti-skid torque of the front wheel and the front wheel correction torque.

In one possible implementation, the obtaining of the ideal adhesion coefficient of the road surface to be traveled includes:

acquiring the road surface type of a road surface to be driven;

searching a sliding adhesion coefficient corresponding to the road surface type from a preset first comparison table, and taking the sliding adhesion coefficient as an ideal adhesion coefficient of the road surface to be driven;

the first comparison table stores corresponding relations between various different road surface types and sliding adhesion coefficients.

In one possible implementation, the method further includes:

under a steering driving working condition, acquiring a steering signal, wherein the steering signal comprises an understeer signal and an oversteer signal, and the steering driving working condition comprises a left steering driving working condition and a right steering driving working condition;

correspondingly, the sending of the torque reduction request to the driving motor corresponding to the slipping driving wheel comprises:

under the left-steering driving condition, if an understeer signal is received, taking a left rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the left rear wheel;

under the left-hand steering running condition, if an oversteer signal is received, taking the right front wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right front wheel;

under the right steering running condition, if an understeer signal is received, taking the right rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right rear wheel;

and under the right steering running condition, if an oversteer signal is received, the left front wheel is taken as the slipping driving wheel, and a torque reduction request is sent to a driving motor corresponding to the left front wheel.

In a second aspect, the present application provides a drive control apparatus for a four-wheel drive vehicle, comprising:

the first acquisition unit is used for acquiring the actual adhesion coefficient of the road surface where the slipping driving wheel is located if the driving wheel slips under the driving working condition;

a second acquisition unit for acquiring a vertical load of the slipping drive wheel;

a first calculation unit configured to calculate an actual anti-skid torque of the slipping drive wheel based on the actual adhesion coefficient calculated by the first acquisition unit and the vertical load acquired by the second acquisition unit;

the first control unit is used for sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for instructing the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque calculated by the first calculation unit;

and the second control unit is used for sending a braking request to a braking mechanism corresponding to the slipping driving wheel if the slipping driving wheel does not return to normal after the first control unit sends a torque reduction request to the driving motor corresponding to the slipping driving wheel, wherein the braking request is used for instructing the braking mechanism to reduce the rotating speed of the slipping driving wheel.

In one possible implementation, the drive control device further includes:

the third acquisition unit is used for acquiring the actual output torque of the slipping driving wheel after the first control unit sends a torque reduction request to the driving motor corresponding to the slipping driving wheel;

the second calculation unit is used for calculating the difference between the actual output torque acquired by the third acquisition unit and the actual anti-skid torque calculated by the first calculation unit to obtain the anti-skid braking torque;

accordingly, the braking request sent by the second control unit to the braking mechanism corresponding to the slipping drive wheel is used to instruct the braking mechanism to provide the anti-slip braking torque to the slipping drive wheel to reduce the rotational speed of the slipping drive wheel.

In one possible implementation, the drive control device further includes:

the third calculating unit is used for calculating the slip rate of the slipping driving wheel if the driving wheel slips under the driving working condition;

the fourth acquisition unit is used for acquiring the road surface type of the road surface where the skid driving wheel is located;

correspondingly, the first obtaining unit is specifically configured to search a driving adhesion coefficient corresponding to the slip ratio and the road surface type of the road surface where the slipping driving wheel is located from a preset second comparison table, and use the driving adhesion coefficient as an actual adhesion coefficient of the road surface where the slipping driving wheel is located;

In one possible implementation, the drive control device further includes:

the fifth acquisition unit is used for acquiring the ideal adhesion coefficient of the road surface to be driven before the first acquisition unit acquires the actual adhesion coefficient of the road surface where the skid driving wheel is located;

a sixth acquiring unit for acquiring a vertical load of the driving wheel;

and a fourth calculation unit configured to calculate an ideal anti-skid torque of the drive wheel based on the ideal adhesion coefficient acquired by the fifth acquisition unit and the vertical load of the drive wheel acquired by the sixth acquisition unit, and set the ideal anti-skid torque as a maximum output torque of the drive wheel corresponding to the drive motor.

In one possible implementation, the drive control device further includes:

the torque correction unit is used for correcting the ideal anti-skid torque calculated by the fourth calculation unit according to a preset front and rear wheel torque distribution strategy to obtain the ideal anti-skid torque of the front wheel and the ideal anti-skid torque of the rear wheel;

the fourth calculating unit is further used for setting the ideal anti-skid torque of the front wheel obtained by correcting the torque correcting unit as the maximum output torque of the driving motor corresponding to the front driving wheel and setting the ideal anti-skid torque of the rear wheel obtained by correcting the torque correcting unit as the maximum output torque of the driving motor corresponding to the rear driving wheel under the working condition of ramp driving;

if the working condition is an uphill working condition, the ideal anti-skid torque of the rear wheel is larger than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheel is smaller than the ideal anti-skid torque; and if the vehicle is in a downhill working condition, the ideal anti-skid torque of the rear wheels is smaller than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheels is larger than the ideal anti-skid torque.

In one possible implementation, the drive control device further includes:

a third control unit, configured to calculate a difference between the actual anti-skid torque obtained by the first calculation unit and the ideal anti-skid torque of the front wheel obtained by the torque correction unit, as a rear wheel correction torque, when the slipping driving wheel is the front driving wheel; sending a torque increasing request to a driving motor corresponding to a rear driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal anti-skid torque of the rear wheel and the rear wheel correcting torque;

a fourth control unit for calculating a difference between the actual anti-skid torque obtained by the first calculation unit and the ideal anti-skid torque of the rear wheel obtained by the torque correction unit as a front wheel correction torque when the slipping drive wheel is the rear drive wheel; and sending a torque increasing request to a driving motor corresponding to the front driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal anti-skid torque of the front wheel and the front wheel correction torque.

In one possible implementation, the drive control device further includes:

a seventh obtaining unit, configured to obtain a road surface type of a road surface to be traveled;

the fifth obtaining unit is specifically configured to search a sliding adhesion coefficient corresponding to the road surface type obtained by the seventh obtaining unit from a preset first comparison table, and use the sliding adhesion coefficient as an ideal adhesion coefficient of the road surface to be driven;

In one possible implementation, the drive control device further includes:

the eighth acquiring unit is used for acquiring a steering signal under a steering driving working condition, wherein the steering signal comprises an understeer signal and an oversteer signal, and the steering driving working condition comprises a left steering driving working condition and a right steering driving working condition;

correspondingly, the first control unit is specifically configured to:

In a third aspect, the present application provides a vehicle comprising a controller, the controller comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the method as described in the first aspect or any one of the possible implementations of the first aspect when executing the computer program.

In a fourth aspect, embodiments of the present application provide a computer-readable storage medium, which stores a computer program, and the computer program, when executed by a processor, implements the steps of the method according to the first aspect or any one of the possible implementation manners of the first aspect.

When the driving wheel is detected to be slipped under the driving working condition, the actual adhesion coefficient of the road surface where the slipped driving wheel is located is obtained; acquiring a vertical load of a slipping driving wheel; calculating an actual anti-skid torque of the slipping drive wheel based on the actual adhesion coefficient and the vertical load; sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for indicating the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque; and if the slipping driving wheels are not recovered to be normal, sending a braking request to a braking mechanism corresponding to the slipping driving wheels, wherein the braking request is used for indicating the braking mechanism to reduce the rotating speed of the slipping driving wheels. It is thus clear that this application calculates actual antiskid moment of torsion according to current road surface condition on the one hand, reduces the moment of torsion that driving motor applyed to the drive wheel that skids and makes the drive wheel that skids break away from the state of skidding, and on the other hand when falling the turn round still not make the drive wheel that skids break away from the state of skidding, brakes the rotational speed in order to reduce the drive wheel that skids through arrestment mechanism to the drive wheel that skids, can control the timely recovery of the drive wheel that skids normally to promote the stability of vehicle, reduce the vehicle and control the risk.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.

FIG. 1 is a schematic diagram of the hardware components of a control system of a four-wheel drive vehicle according to an embodiment of the present application;

FIG. 2 is a flowchart of an implementation of a driving control method for a four-wheel drive vehicle according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of a drive control device of a four-wheel drive vehicle according to an embodiment of the present application;

fig. 4 is a schematic diagram of a controller of a vehicle according to an embodiment of the present application.

Detailed Description

In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present application with unnecessary detail.

To make the objects, technical solutions and advantages of the present application more clear, the following description is made by way of specific embodiments with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a hardware component of a control system of a four-wheel drive vehicle according to an embodiment of the present disclosure; as shown in fig. 1, the four-wheel drive vehicle control system includes one vehicle control unit 10, four motor controllers (11, 12, 13, 14), four drive motors (21, 22, 23, 24), four brake-by-wire (51, 52, 53, 54), and four drive wheels (61, 62, 63, 64). Wherein for each drive wheel, a drive motor and a motor controller are associated. The vehicle control unit 10 sends a request to the driving motor through the motor controller, and controls torque output of the driving motor.

In other embodiments, two motor controllers may be used, i.e., one for both front wheels and one for both rear wheels.

The execution subject of the embodiment of the present application may be the vehicle control unit 10.

Referring to fig. 2, it shows a flowchart of an implementation of the driving control method for a four-wheel drive vehicle provided in the embodiment of the present application, and details are as follows:

in step 201, if the driving wheel slips under the driving condition, acquiring an actual adhesion coefficient of a road surface where the slipping driving wheel is located;

the adhesion coefficient is the adhesion capacity of the tire on different road surfaces, and is the ratio of the adhesion force to the normal (perpendicular to the road surface) pressure of the wheel. The rough calculation can be regarded as the static friction coefficient between the tire and the road surface. The adhesion coefficient is related to the road surface and the tires, and the larger the adhesion coefficient is, the larger the available adhesion force is, and the less the automobile slips easily.

The driving working condition refers to the working condition of starting or accelerating the vehicle, and when the vehicle starts or accelerates, the tire is easy to slip when the adhesion coefficient is small due to different adhesion coefficients of different types of road surfaces.

In the embodiment of the application, the vehicle control unit may calculate to determine whether a wheel slips according to the rotation speed and the rolling radius of the wheel and the current speed of the vehicle, for example, when the rotation speed of a certain wheel multiplied by the rolling radius of the certain wheel is greater than the horizontal speed of the certain wheel, it may be determined that the certain wheel slips.

Optionally, in an embodiment, the step 201 may be implemented by:

In the embodiment of the application, the slip rate refers to the slip degree of the wheels when the vehicle starts in an acceleration mode, and the slip rate can be calculated through the following formula:

where S denotes a slip ratio, R denotes a rolling radius (meter) of the wheel, W denotes a rotational angular velocity (radians per second) of the wheel, and V denotes a longitudinal velocity (meter per second) of the wheel center.

In addition, the slip rate also reflects to some extent whether the wheel is slipping, and in some implementations, the slip rate of the wheel may be directly calculated, and when the wheel slip rate is less than a set threshold, it is determined that the wheel is not slipping, and when the slip rate is not less than the set threshold, it is determined that the wheel is slipping.

In the embodiment of the application, the road surface image can be shot through the camera, and then the road surface type of the road surface where the slipping driving wheel is located is obtained through image analysis and recognition.

In the embodiment of the application, a comparison table of correspondence relations among various different road surface types, slip ratios and driving adhesion coefficients is stored in advance, and each correspondence relation can be obtained by performing test tests on various types of road surfaces. For example, the above correspondence relationship may be obtained by testing each of different types of road surfaces such as a snowfield road, a wet concrete road, and a dry asphalt road. After the slip ratio and the road surface type are determined, the actual adhesion coefficient of the road surface on which the slipping drive wheels are located can be determined by a look-up table.

In step 202, acquiring a vertical load of a slipping drive wheel;

in the embodiment of the present application, the vertical load of the tire may be an intrinsic parameter of the vehicle, and may be directly obtained or calculated by other methods in the prior art.

Calculating an actual slip torque of the slipping drive wheels based on the actual adhesion coefficient and the vertical load in step 203;

in the present embodiment, the actual anti-skid torque may be understood as the maximum torque at which the wheels do not skid on the corresponding road surface, that is, if the torque applied to the driving wheels is greater than the actual anti-skid torque, the wheels may skid on the corresponding road surface. The actual slip torque may be calculated from the actual stick coefficient and the vertical load, for example, the actual slip torque may be a product of the actual stick coefficient and the vertical load.

In step 204, sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for instructing the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque;

in the embodiment of the present application, since the slip is caused by that the torque currently applied to the driving wheel is larger than the actual anti-slip torque, a torque reduction request may be sent to the driving motor corresponding to the slipping driving wheel to instruct the driving motor to limit the maximum output torque thereof to the actual anti-slip torque, so that the slipping driving wheel may not slip any more.

If the slipping drive wheels do not return to normal in step 205, a braking request instructing the braking mechanism to reduce the rotational speed of the slipping drive wheels is sent to the braking mechanism corresponding to the slipping drive wheels.

In the embodiment of the present application, after the torque down request is sent to the drive motor corresponding to the slipping drive wheel, the actual output torque of the drive motor corresponding to the slipping drive wheel may be dropped above the actual anti-slip torque due to some reasons, in which case the slipping drive wheel may still be in a slipping state and not be recovered to normal.

If the slipping drive wheels are not back to normal (are still slipping), a braking request may be sent to the braking mechanism corresponding to the slipping drive wheels to instruct the braking mechanism to reduce the rotational speed of the slipping drive wheels. Illustratively, the brake-by-wire (31, 32, 33, 34) shown in fig. 1 can be commanded using brake-by-wire techniques to actuate and control the braking mechanism to apply a corresponding braking force to the slipping drive wheels to reduce the rotational speed of the slipping drive wheels to return the slipping drive wheels from a slipping condition to a normal non-slipping condition.

According to the method, when the driving wheel is detected to be slipped under the driving working condition, the actual adhesion coefficient of the road surface where the slipped driving wheel is located is obtained; acquiring a vertical load of a slipping driving wheel; calculating an actual anti-skid torque of the slipping drive wheel based on the actual adhesion coefficient and the vertical load; sending a torque reduction request to a driving motor corresponding to the slipping driving wheel, wherein the torque reduction request is used for indicating the driving motor to limit the maximum output torque of the driving motor to the actual anti-slipping torque; and if the slipping driving wheels are not recovered to be normal, sending a braking request to a braking mechanism corresponding to the slipping driving wheels, wherein the braking request is used for indicating the braking mechanism to reduce the rotating speed of the slipping driving wheels. It is thus clear that this application calculates actual antiskid moment of torsion according to current road surface condition on the one hand, reduces the moment of torsion that driving motor applyed to the drive wheel that skids and makes the drive wheel that skids break away from the state of skidding, and on the other hand when falling the turn round still not make the drive wheel that skids break away from the state of skidding, brakes the rotational speed in order to reduce the drive wheel that skids through arrestment mechanism to the drive wheel that skids, can control the timely recovery of the drive wheel that skids normally to promote the stability of vehicle, reduce the vehicle and control the risk.

Optionally, in an embodiment, the step 205 may further include: if the slipping driving wheel does not return to normal, acquiring the actual output torque of the slipping driving wheel; calculating the difference between the actual output torque and the actual anti-skid torque to obtain an anti-skid braking torque;

In the embodiment of the present application, after the torque reduction request is sent to the driving motor corresponding to the slipping driving wheel, if the slipping driving wheel does not return to normal, the actual output torque of the slipping driving wheel may be obtained, and at this time, the actual output torque should be greater than the actual anti-slip torque, a difference between the actual output torque and the actual anti-slip torque may be calculated, and the difference between the actual output torque and the actual anti-slip torque may be used as the anti-slip braking torque, and the braking request is sent to the braking mechanism corresponding to the slipping driving wheel, so as to instruct the driving mechanism to apply the anti-slip braking torque to the slipping driving wheel, so as to reduce the rotation speed of the slipping driving wheel.

In the present embodiment, in the case where the slipping drive wheels cannot actually execute the actual anti-slip torque, the slipping drive wheels are assisted to be controlled to decelerate by the braking mechanism by converting the torque portion that cannot be executed into the braking control, so that the slipping drive wheels can be better controlled to return to normal.

Optionally, the present application further provides an embodiment of driving antiskid control under a steering driving condition, specifically as follows: under a steering driving working condition, acquiring a steering signal, wherein the steering signal comprises an understeer signal and an oversteer signal, and the steering driving working condition comprises a left steering driving working condition and a right steering driving working condition;

correspondingly, the sending of the torque reduction request to the driving motor corresponding to the slipping driving wheel comprises: under the left-steering driving condition, if an understeer signal is received, taking a left rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the left rear wheel; under the left-hand steering running condition, if an oversteer signal is received, taking the right front wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right front wheel; under the right steering running condition, if an understeer signal is received, taking the right rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right rear wheel; and under the right steering running condition, if an oversteer signal is received, the left front wheel is taken as the slipping driving wheel, and a torque reduction request is sent to a driving motor corresponding to the left front wheel.

In this embodiment, in the steering driving condition, the slipping driving wheel can be determined by the steering signal, and the control of the wheel slip in the steering driving condition is realized by performing the above-mentioned torque reduction operation and braking operation on the corresponding slipping driving wheel.

Optionally, the present application further provides an embodiment of a vehicle pre-antiskid strategy, and the steps of the embodiment may be implemented before step 201, and specifically may include: acquiring an ideal adhesion coefficient of a road surface to be driven;

acquiring a vertical load of a driving wheel; and calculating ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and the vertical load of the driving wheel, and setting the ideal anti-skid torque as the maximum output torque of the driving motor corresponding to the driving wheel.

The maximum value of the adhesion coefficient is the peak adhesion coefficient, the adhesion coefficient when the vehicle is locked to slide is called as the slip adhesion coefficient, the slip adhesion coefficient is used as the ideal adhesion coefficient to be combined with the vertical load of the driving wheel to calculate and obtain the ideal anti-skid torque of the driving wheel, the ideal anti-skid torque is further set as the maximum output torque of the driving wheel corresponding to the driving motor, and the vehicle can be guaranteed not to easily slip under the normal condition through the setting of the maximum output torque.

Optionally, the above implementation manner of obtaining the ideal adhesion coefficient of the road surface to be traveled may include: acquiring the road surface type of a road surface to be driven; searching a sliding adhesion coefficient corresponding to the road surface type from a preset first comparison table, and taking the sliding adhesion coefficient as an ideal adhesion coefficient of the road surface to be driven; the first comparison table stores corresponding relations between various different road surface types and sliding adhesion coefficients.

In this embodiment, the road surface to be traveled can be photographed by the camera, and then the road surface type of the road surface to be traveled is obtained through image analysis and recognition. The corresponding relation between various different road surface types and the sliding adhesion coefficients is obtained through a pre-test experiment and stored as a first comparison table, and then the ideal adhesion coefficients of the road surface to be driven can be obtained by searching the first comparison table according to the road surface type of the road surface to be driven.

In this embodiment, the road surface types may include: asphalt or concrete (dry) road, the corresponding slip adhesion coefficient may be 0.75; asphalt (wet) road, the corresponding sliding adhesion coefficient can be 0.45-0.6; concrete (wet) road, the corresponding slip adhesion coefficient may be 0.7; a gravel road, the corresponding slip stick coefficient may be 0.55; a soil (trunk) road, the corresponding sliding adhesion coefficient may be 0.65; the corresponding sliding adhesion coefficient of the soil (wet) road can be 0.4-0.5; snow (compaction) road, the corresponding sliding adhesion coefficient can be 0.15; for an ice road, the corresponding coefficient of sliding adhesion may be 0.07.

Optionally, the present application further provides an embodiment of front and rear wheel distribution of ideal anti-skid torque for a hill condition, which specifically may include: calculating ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and the vertical load of the driving wheel; correcting the ideal anti-skid torque according to a preset front and rear wheel torque distribution strategy to obtain an ideal anti-skid torque of the front wheel and an ideal anti-skid torque of the rear wheel; under the working condition of ramp driving, the ideal anti-skid torque of the front wheels is set as the maximum output torque of the driving motor corresponding to the front driving wheels, and the ideal anti-skid torque of the rear wheels is set as the maximum output torque of the driving motor corresponding to the rear driving wheels.

Regarding the front and rear wheel torque distribution strategy, for example, in an uphill situation, the front and rear wheel distribution ratio may be 4: that is, if the entire vehicle requires 100 newtons of driving force, 40 newtons are assigned to the front wheels and 60 newtons are assigned to the rear wheels when ascending. Correspondingly, in the case of uphill slope, the distribution ratio of the front wheels to the rear wheels may be 6: 4, that is, if the entire vehicle requires 100 newtons of driving force, 60 newtons are distributed to the front wheels and 40 newtons are distributed to the rear wheels when going downhill.

Aiming at the torque distribution strategy of the front wheel and the rear wheel, the ideal anti-skid torque can be distributed to the front wheel and the rear wheel according to the corresponding strategy under the working condition of a ramp so as to adapt to the corresponding working condition.

Further, for the previous embodiment, the present embodiment further provides that, in addition to performing corresponding torque reduction on the slipping driving wheel, corresponding torque increase may be performed on the opposite wheel (the relative relationship between the front wheel and the rear wheel) of the slipping driving wheel under the condition of hill driving, so as to ensure that the total desired torque of the driver is not attenuated while preventing slipping, so as to more quickly enable the vehicle to escape from the slipping condition. The method specifically comprises the following steps:

It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

The following are apparatus embodiments of the present application, and for details not described in detail therein, reference may be made to the corresponding method embodiments described above.

Fig. 3 is a schematic structural diagram of a drive control device of a four-wheel drive vehicle according to an embodiment of the present application, and for convenience of description, only the portions related to the embodiment of the present application are shown, and detailed description is as follows:

as shown in fig. 3, the drive control device 3 may include: a first acquisition unit 31, a second acquisition unit 32, a first calculation unit 33, a first control unit 34, and a second control unit 35.

The first obtaining unit 31 is configured to obtain an actual adhesion coefficient of a road surface where a slipping driving wheel is located if the driving wheel slips under a driving condition;

a second acquiring unit 32 for acquiring a vertical load of the slipping driving wheel;

a first calculation unit 33 for calculating an actual antiskid torque of the slipping drive wheel based on the actual adhesion coefficient calculated by the first acquisition unit 31 and the vertical load acquired by the second acquisition unit 32;

a first control unit 34, configured to send a torque reduction request to a driving motor corresponding to the slipping driving wheel, where the torque reduction request is used to instruct the driving motor to limit the maximum output torque of the driving motor to the actual anti-slip torque calculated by the first calculation unit 33;

and a second control unit 35, configured to send a braking request to the braking mechanism corresponding to the slipping driving wheel after the first control unit 34 sends a torque reduction request to the driving motor corresponding to the slipping driving wheel, if the slipping driving wheel is not recovered to be normal, the braking request being used for instructing the braking mechanism to reduce the rotation speed of the slipping driving wheel.

Optionally, the drive control device 3 may further include:

a third obtaining unit, configured to obtain an actual output torque of the slipping driving wheel after the first control unit 34 sends a torque reduction request to the driving motor corresponding to the slipping driving wheel;

a second calculating unit, configured to calculate a difference between the actual output torque acquired by the third acquiring unit and the actual anti-skid torque calculated by the first calculating unit 33, so as to obtain an anti-skid braking torque;

accordingly, the braking request sent by the second control unit 35 to the braking mechanism corresponding to the slipping driving wheel is used to instruct the braking mechanism to provide the anti-slip braking torque to the slipping driving wheel to reduce the rotational speed of the slipping driving wheel.

Optionally, the drive control device 3 may further include:

correspondingly, the first obtaining unit 31 is specifically configured to search, from a preset second comparison table, a driving adhesion coefficient corresponding to the slip ratio and the road surface type of the road surface on which the slipping driving wheel is located, and use the driving adhesion coefficient as an actual adhesion coefficient of the road surface on which the slipping driving wheel is located; the second comparison table stores corresponding relations among various different road surface types, slip ratios and driving adhesion coefficients.

Optionally, the driving control device 3 may further include:

a fifth obtaining unit, configured to obtain an ideal adhesion coefficient of the road surface to be driven before the first obtaining unit 31 obtains the actual adhesion coefficient of the road surface on which the slipping driving wheel is located;

a sixth acquiring unit for acquiring a vertical load of the driving wheel;

Optionally, the drive control device 3 may further include:

the fourth calculating unit is further used for setting the ideal anti-skid torque of the front wheel obtained by correction of the torque correcting unit as the maximum output torque of the driving motor corresponding to the front driving wheel and setting the ideal anti-skid torque of the rear wheel obtained by correction of the torque correcting unit as the maximum output torque of the driving motor corresponding to the rear driving wheel under the working condition of ramp driving;

if the vehicle is in an uphill working condition, the ideal anti-skid torque of the rear wheels is larger than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheels is smaller than the ideal anti-skid torque; and if the vehicle is in a downhill working condition, the ideal anti-skid torque of the rear wheel is smaller than the ideal anti-skid torque, and the ideal anti-skid torque of the front wheel is larger than the ideal anti-skid torque.

Optionally, the drive control device 3 may further include:

a third control unit configured to calculate a difference between the actual anti-skid torque obtained by the first calculation unit 33 and the ideal anti-skid torque of the front wheel obtained by the torque correction unit as a rear wheel correction torque when the slipping drive wheel is the front drive wheel; sending a torque increasing request to a driving motor corresponding to a rear driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal antiskid torque of the rear wheel and the correction torque of the rear wheel;

a fourth control unit for calculating a difference between the actual anti-skid torque obtained by the first calculation unit 33 and the ideal anti-skid torque of the rear wheel obtained by the torque correction unit as a front wheel correction torque when the slipping drive wheel is the rear drive wheel; and sending a torque increasing request to a driving motor corresponding to the front driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal anti-skid torque of the front wheel and the front wheel correcting torque.

Optionally, the drive control device 3 may further include:

the fifth obtaining unit is specifically configured to search a sliding adhesion coefficient corresponding to the road surface type obtained by the seventh obtaining unit from a preset first comparison table, and use the sliding adhesion coefficient as an ideal adhesion coefficient of the road surface to be driven; the first comparison table stores corresponding relations between various different road surface types and sliding adhesion coefficients.

Optionally, the drive control device 3 may further include:

correspondingly, the first control unit 34 is specifically configured to:

under the left-steering driving condition, if an understeer signal is received, taking a left rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the left rear wheel; under the left-hand steering running condition, if an oversteer signal is received, taking the right front wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right front wheel; under the right steering running condition, if an understeer signal is received, taking the right rear wheel as the slipping driving wheel, and sending a torque reduction request to a driving motor corresponding to the right rear wheel; and under the right steering running condition, if an oversteer signal is received, the left front wheel is taken as the slipping driving wheel, and a torque reduction request is sent to a driving motor corresponding to the left front wheel.

Embodiments of the present application also provide a computer program product having program code for performing steps in any of the above described embodiments of a method of drive control for a four-wheel drive vehicle, such as steps 201 to 205 shown in fig. 2, when the program code is run on a corresponding processor, controller, computing device or vehicle.

Those skilled in the art will appreciate that the methods presented in the embodiments of the present application and the apparatus pertaining thereto may be implemented in various forms of hardware, software, firmware, special purpose processors, or a combination thereof. The special-purpose processor may include an Application Specific Integrated Circuit (ASIC), a Reduced Instruction Set Computer (RISC), and/or a Field Programmable Gate Array (FPGA). The proposed method and apparatus are preferably implemented as a combination of hardware and software. The software is preferably installed as an application program on a program storage device.

Fig. 4 is a schematic diagram of a controller 4 of a vehicle according to an embodiment of the present application. As shown in fig. 4, the controller 4 of this embodiment includes: a processor 40, a memory 41 and a computer program 42 stored in said memory 41 and executable on said processor 40. The processor 40, when executing the computer program 42, implements the steps in each of the above-described four-wheel drive vehicle drive control method embodiments, such as the steps 201 to 205 shown in fig. 2. Alternatively, the processor 40, when executing the computer program 42, implements the functions of the units in the device embodiments described above, such as the functions of the units 31 to 35 shown in fig. 3.

Illustratively, the computer program 42 may be divided into one or more modules/units, which are stored in the memory 41 and executed by the processor 40 to implement the solution provided herein. The one or more units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of the computer program 42 in the controller 4. For example, the computer program 42 may be divided into the units 31 to 35 shown in fig. 3.

The controller 4 may include, but is not limited to, a processor 40, a memory 41. Those skilled in the art will appreciate that fig. 4 is merely an example of the controller 4, and does not constitute a limitation of the controller 4, and may include more or fewer components than shown, or some components may be combined, or different components, e.g., the vehicle may also include input-output devices, network access devices, buses, etc.

The Processor 40 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic, discrete hardware components, etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

The memory 41 may be an internal storage unit of the controller 4, or may be an external storage device of the vehicle 4, such as a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), or the like provided on the vehicle 4. Further, the memory 41 may also include both an internal storage unit of the controller 4 and an external storage device. The memory 41 is used for storing the computer program and other programs and data required by the vehicle. The memory 41 may also be used to temporarily store data that has been output or is to be output.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the above-mentioned division of the functional units and modules is illustrated, and in practical applications, the above-mentioned function distribution may be performed by different functional units and modules according to needs, that is, the internal structure of the apparatus is divided into different functional units or modules to perform all or part of the above-mentioned functions. Each functional unit and module in the embodiments may be integrated in one processing unit, or each unit may exist alone physically, or two or more units are integrated in one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units and modules are only used for distinguishing one functional unit from another, and are not used for limiting the protection scope of the present application. The specific working processes of the units and modules in the system may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the modules or units is only one type of logical functional division, and other divisions may be realized in practice, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in an electrical, mechanical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, all or part of the flow in the method of the embodiments described above can be realized by a computer program, which can be stored in a computer-readable storage medium and can realize the steps of the embodiments of the methods described above when the computer program is executed by a processor. Wherein the computer program comprises computer program code, which may be in the form of source code, object code, an executable file or some intermediate form, etc. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, usb disk, removable hard disk, magnetic disk, optical disk, computer Memory, Read-Only Memory (ROM), Random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution medium, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, computer readable media which may not include electrical carrier signals and telecommunications signals in accordance with legislation and patent practice.

Furthermore, features of the embodiments shown in the drawings of the present application or of the various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, each feature described in one example of one embodiment can be combined with one or more other desired features from other embodiments to yield yet further embodiments, which are not described in text or with reference to the accompanying drawings.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A drive control method of a four-wheel drive vehicle, characterized by comprising:

acquiring a vertical load of a slipping driving wheel;

2. A drive control method for a four-wheel drive vehicle according to claim 1, further comprising, after sending a torque down request to the drive motor corresponding to the slipping drive wheel:

acquiring actual output torque of a slipping driving wheel;

calculating the difference between the actual output torque and the actual antiskid torque to obtain an antiskid braking torque;

3. A drive control method for a four-wheel drive vehicle according to claim 1 or 2, wherein said obtaining an actual adhesion coefficient of a road surface on which a slipping drive wheel is located if the drive wheel slips under the driving condition comprises:

4. A drive control method for a four-wheel drive vehicle according to claim 1 or 2, wherein before said obtaining an actual adhesion coefficient of a road surface on which the slipping drive wheel is located if the drive wheel slips under the driving condition, further comprises:

acquiring an ideal adhesion coefficient of a road surface to be driven;

acquiring a vertical load of a driving wheel;

5. A drive control method of a four-wheel drive vehicle according to claim 4, wherein said calculating a desired anti-skid torque of the drive wheels based on the desired adhesion coefficient and the vertical load of the drive wheels, and setting the desired anti-skid torque as a maximum output torque of the drive motor for the drive wheels comprises:

calculating ideal anti-skid torque of the driving wheel based on the ideal adhesion coefficient and the vertical load of the driving wheel;

correcting the ideal anti-skid torque according to a preset front and rear wheel torque distribution strategy to obtain an ideal anti-skid torque of a front wheel and an ideal anti-skid torque of a rear wheel;

6. A drive control method of a four-wheel drive vehicle according to claim 5, further comprising, after said calculating a desired anti-skid torque of the drive wheels based on said desired adhesion coefficient and vertical loads of the drive wheels:

if the slipping driving wheel is a front driving wheel, calculating the difference between the actual anti-slipping torque and the ideal anti-slipping torque of the front wheel to be used as a rear wheel correction torque; sending a torque increasing request to a driving motor corresponding to a rear driving wheel so as to increase the maximum output torque of the driving motor to the sum of the ideal antiskid torque of the rear wheel and the rear wheel correction torque;

7. A drive control method of a four-wheel drive vehicle according to claim 4, wherein said obtaining an ideal adhesion coefficient of a road surface to be traveled includes:

acquiring the road surface type of a road surface to be driven;

8. A drive control method of a four-wheel drive vehicle according to claim 1 or 2, characterized by further comprising:

9. A drive control device for a four-wheel drive vehicle, characterized by comprising:

and the second control unit is used for sending a braking request to a braking mechanism corresponding to the slipping driving wheel if the slipping driving wheel does not return to normal after the first control unit sends a torque reduction request to the driving motor corresponding to the slipping driving wheel, wherein the braking request is used for indicating the braking mechanism to reduce the rotating speed of the slipping driving wheel.

10. A vehicle comprising a controller including a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements the steps of the drive control method of a four-wheel drive vehicle as claimed in any one of claims 1 to 8 above when executing the computer program.

11. A computer-readable storage medium, in which a computer program is stored, which, when being executed by a processor, carries out the steps of the drive control method for a four-wheel drive vehicle according to any one of claims 1 to 8 above.