CN118833199A

CN118833199A - Calibration method of vehicle reference speed, four-wheel drive system and vehicle

Info

Publication number: CN118833199A
Application number: CN202411312398.2A
Authority: CN
Inventors: 李昕聪; 孟祥希; 李帅; 李天竺
Original assignee: FAW Group Corp
Current assignee: FAW Group Corp
Priority date: 2024-09-20
Filing date: 2024-09-20
Publication date: 2024-10-25

Abstract

The invention discloses a calibration method of a vehicle reference speed, a four-wheel drive system and a vehicle, and relates to the technical field of vehicle control. The calibration method is applied to the four-wheel drive system, and comprises the following steps: detecting a first slip amount and a slip duration of a wheel; controlling wheel braking according to the first slip amount and the slip duration; in the braking process of the wheel, detecting a second slip quantity of the wheel by taking a first preset time as an interval time, wherein the second slip quantity and the first slip quantity are slip distances of the wheel relative to the ground in different moments in unit time; and when the second slip quantity is smaller than or equal to the preset slip threshold value, controlling the wheels to stop braking, and calculating the current reference speed of the vehicle. The invention reduces the slip degree of the wheels in advance before the calculation of the reference speed of the vehicle, thereby reducing the influence of the slip of the wheels on the calculation of the reference speed of the vehicle and further improving the accuracy of the calculation of the reference speed.

Description

Calibration method of vehicle reference speed, four-wheel drive system and vehicle

Technical Field

The present invention relates to the field of vehicle control technologies, and in particular, to a method for calibrating a reference speed of a vehicle, a four-wheel drive system, and a vehicle.

Background

The conventional vehicle speed estimation method usually collects data through a speed sensor and an acceleration sensor mounted on a wheel, and then performs a series of algorithm processes on the collected data to estimate a reference speed of the vehicle. However, when the wheel slips, a difference occurs between the actual rotational speed of the wheel and the actual running speed of the vehicle, thereby affecting the accuracy of the reference speed estimation, resulting in a decrease in control accuracy of safety auxiliary systems such as an antilock brake system, a vehicle dynamic stability control system, and a traction control system.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the invention provides a calibration method for the reference speed of the vehicle, which can reduce the influence of wheel slip on the calculation of the reference speed of the vehicle, thereby improving the accuracy of the calculation of the reference speed.

The invention also proposes a vehicle controller, a four-wheel drive system, a vehicle, an electronic device and a computer readable storage medium.

A calibration method of a vehicle reference speed according to an embodiment of the first aspect of the present invention is applied to a four-wheel drive system, and includes:

Detecting a first slip amount and a slip duration of a wheel;

Controlling the wheel brake according to the first slip amount and the slip duration;

in the braking process of the wheel, detecting a second slip quantity of the wheel by taking a first preset time as an interval time, wherein the second slip quantity and the first slip quantity are slip distances of the wheel relative to the ground in different moments in unit time;

and when the second slip quantity is smaller than or equal to a preset slip threshold value, controlling the wheels to stop braking, and calculating the current reference speed of the vehicle.

The method for calibrating the reference speed of the vehicle has at least the following beneficial effects:

According to the embodiment of the invention, the slip degree of the wheel is accurately estimated by detecting the first slip amount and the slip duration of the wheel, and the wheel brake is controlled according to the slip degree of the wheel, so that the slip phenomenon of the wheel is inhibited; in the braking process of the wheel, periodically detecting a second slip quantity of the wheel by taking the first preset time as an interval time, thereby realizing dynamic updating of the slip degree of the wheel; when the second slip quantity is smaller than or equal to the preset slip threshold value, the influence of the slip of the wheel on the calculation of the reference speed of the vehicle can be judged to be reduced, the wheel is controlled to stop braking and the current reference speed of the vehicle is calculated, the slip degree of the wheel is reduced in advance before the calculation of the reference speed of the vehicle is realized, the influence of the slip of the wheel on the calculation of the reference speed of the vehicle is reduced, and the accuracy of the calculation of the reference speed is improved.

According to some embodiments of the invention, the detecting a first slip amount and a slip duration of the wheel includes:

Acquiring the current longitudinal acceleration and lateral acceleration of the wheel;

calculating an effective coefficient of friction of the wheel from the longitudinal acceleration and the lateral acceleration;

acquiring a preset slippage reference set, wherein the slippage reference set comprises a plurality of reference slippage data corresponding to a plurality of effective friction coefficients one by one;

and selecting the reference slippage data corresponding to the effective friction coefficient from the slippage reference set as the first slippage.

According to some embodiments of the invention, the detecting the first slip amount and the slip duration of the wheel further includes:

When the first slip amount is larger than the preset slip threshold value, detecting a third slip amount of the wheel by taking a second preset time as an interval time, wherein the third slip amount, the first slip amount and the second slip amount are slip distances of the wheel relative to the ground in different moments in unit time;

And when the third slippage is larger than the preset slippage threshold, repeatedly detecting the third slippage by taking the second preset time as interval time, recording the second preset time, and overlapping all recorded second preset time as slippage duration until the third slippage is smaller than or equal to the preset slippage threshold.

According to some embodiments of the invention, the controlling the wheel brake according to the first slip amount and the slip duration includes:

Acquiring a preset duration threshold;

And when the slip time length is greater than the preset time length threshold value, controlling front wheel braking at a first side in the vehicle and controlling rear wheel braking at a second side in the vehicle.

According to some embodiments of the invention, the detecting the second slip amount of the wheel at intervals of the first preset time further includes:

And when the second slip amount is larger than the preset slip threshold value, controlling front wheel braking at the second side in the vehicle and controlling rear wheel braking at the first side in the vehicle.

According to some embodiments of the invention, the acquiring the preset duration threshold includes:

Acquiring the current speed of the vehicle;

And inquiring and acquiring the preset duration threshold value from a reference threshold value table according to the current vehicle speed and the effective friction coefficient based on a preset reference threshold value table, wherein the reference threshold value table is used for representing the corresponding relation between the vehicle speed of the vehicle and the effective friction coefficient of the wheels.

respectively obtaining fourth slippage of each wheel;

and determining the smallest one of all the fourth slip amounts as the first slip amount.

A vehicle controller according to an embodiment of a second aspect of the invention, applied to a four-wheel drive system, includes:

A first detection module configured to detect a first slip amount and a slip duration of a wheel;

A braking module configured to control the wheel braking according to the first slip amount and the slip duration;

the second detection module is configured to detect a second slip amount of the wheel with a first preset time as an interval time in the braking process of the wheel, wherein the second slip amount and the first slip amount are slip distances of the wheel relative to the ground in different moments in unit time;

And the execution module is configured to control the wheels to stop braking when the second slip quantity is smaller than or equal to a preset slip threshold value, and calculate the current reference speed of the vehicle.

The vehicle controller according to the embodiment of the invention has at least the following beneficial effects:

According to the embodiment of the invention, the first slip quantity and the slip duration of the wheel are detected through the first detection module, the braking of the wheel is controlled through the braking module according to the first slip quantity and the slip duration, the second slip quantity of the wheel is detected through the second detection module at intervals of a first preset time in the braking process of the wheel, the second slip quantity and the first slip quantity are slip distances of the wheel relative to the ground in different moments, the braking of the wheel is stopped when the second slip quantity is smaller than or equal to a preset slip threshold value through the execution module, the current reference speed of the vehicle is calculated, the slip degree of the wheel is reduced in advance before the calculation of the reference speed of the vehicle is realized, the influence of the wheel slip on the calculation of the reference speed of the vehicle is reduced, and the accuracy of the calculation of the reference speed is improved.

According to a fourth aspect of the embodiment of the present invention, the four-wheel drive system is controlled by applying the calibration method of the vehicle reference speed according to the first aspect of the embodiment.

The four-wheel drive system according to the embodiment of the invention has at least the following beneficial effects:

The four-wheel drive system is controlled by applying the calibration method for the vehicle reference speed according to the embodiment of the first aspect, and by reducing the slip degree of the wheels in advance before the calculation of the vehicle reference speed, the influence of the wheel slip on the calculation of the vehicle reference speed is reduced, the accuracy of the calculation of the reference speed is further improved, more accurate data support is provided for the dynamic stability control system and the traction control system of the vehicle, the four-wheel drive system can be accurately controlled based on more accurate vehicle states, the ground grabbing performance of the four-wheel drive system is further improved, and the running stability and the safety of the four-wheel drive system are further improved.

According to a vehicle of an embodiment of a fourth aspect of the present invention, the four-wheel drive system according to the embodiment of the third aspect is applied.

The vehicle provided by the embodiment of the invention has at least the following beneficial effects:

The vehicle is applied with the four-wheel drive system of the embodiment of the third aspect, and more accurate data support is provided for the dynamic stability control system and the traction control system of the vehicle by improving the accuracy of the calculation of the reference speed of the vehicle, so that the systems can be more effectively intervened, the ground grabbing performance of the four-wheel drive system is enhanced, the operability of the vehicle is improved, the risk of vehicle out of control is reduced, and the stability and the safety in the running process are improved.

An electronic device according to an embodiment of a fifth aspect of the present invention includes: at least one processor and at least one memory for storing at least one program; the at least one program, when executed by the at least one processor, causes the at least one processor to implement the method of calibrating a vehicle reference speed as disclosed in the first aspect.

A computer readable storage medium according to an embodiment of the sixth aspect of the present invention has stored therein processor executable instructions which when executed by a processor are for performing the method of calibrating the vehicle reference speed disclosed in the first aspect.

Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a flow chart showing steps of a method for calibrating a reference speed of a vehicle according to an embodiment of the present invention;

FIG. 2 is a flowchart showing the steps of step S101 in a method for calibrating a reference speed of a vehicle according to an embodiment of the invention;

FIG. 3 is a flowchart showing the steps of step S102 in a method for calibrating a reference speed of a vehicle according to an embodiment of the invention;

FIG. 4 is a flowchart showing the steps of step S1021 in a method for calibrating a reference speed of a vehicle according to an embodiment of the invention;

FIG. 5 is a table of reference thresholds in a method of calibrating a reference speed of a vehicle according to an embodiment of the invention;

FIG. 6 is a flowchart showing the steps of step S101 in a method for calibrating a reference speed of a vehicle according to another embodiment of the present invention;

fig. 7 is a schematic structural diagram of a vehicle controller according to an embodiment of the present invention.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.

In the description of the present invention, it should be understood that the direction or positional relationship indicated with respect to the description of the orientation, such as up, down, etc., is based on the direction or positional relationship shown in the drawings, is merely for convenience of describing the present invention and simplifying the description, and does not indicate or imply that the apparatus or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In the description of the present invention, plural means two or more. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present invention can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

It will be appreciated that the accuracy of the reference vehicle speed, which is one of the core input parameters of the vehicle chassis control function, is directly related to the accuracy and reliability of the control function, and is an essential basis for ensuring stable execution of the vehicle control function. Taking a traction control system as an example, the accuracy of the reference vehicle speed is decisive for the rationality and accuracy of the engine torque control.

Specifically, if the reference vehicle speed estimation is low, the vehicle speed deviation is increased, and unnecessary triggering of the traction control system is easily caused, so that not only is the normal driving flow disturbed, but also the smoothness and the comfort of driving are reduced. Conversely, if the reference vehicle speed is overestimated, in a scenario where traction control system intervention is actually required to ensure driving safety, the system may remain silent due to the unsatisfied triggering conditions, which undoubtedly pose a serious threat to the safety performance of the vehicle, requiring immediate correction to avoid the potential risk.

However, the existing reference speed calculation method generally fails to fully consider the influence of the wheel slip phenomenon on the calculation result, and the neglect directly leads to inaccuracy of the reference speed data. It should be noted that in a two-drive system, the accuracy of the reference vehicle speed benefits from the additional speed reference provided by the non-drive shaft, which mechanism helps to assist in correcting the calculation. However, in a four-wheel drive system, since all wheels are drive shafts, there is a lack of non-drive shafts as independent speed reference sources.

To this end, some embodiments of the present invention provide a calibration method of a vehicle reference speed, which is applied to a four-wheel drive system, and in particular, the four-wheel drive system is suitable for various types of vehicles, which can flexibly distribute power of different proportions between front and rear wheels according to the state of a driving road surface, thereby ensuring the grip performance of the wheels, and the calibration method of the vehicle reference speed is described with reference to fig. 1 to 7.

Referring to fig. 1, in an embodiment of the present invention, a method for calibrating a reference speed of a vehicle includes:

Step S101, detecting a first slip amount and a slip duration of a wheel.

It can be understood that when the vehicle accelerates or runs to a road section with smooth road surface, relative sliding is easy to occur between the wheels and the road surface, so that the reference speed of the vehicle calculated based on the rotation speed of the wheels is greater than the actual speed of the vehicle, that is, the wheel slip interferes with the calculation of the reference speed of the vehicle, and the accuracy of the calculation of the reference speed is affected.

Specifically, when the vehicle is rapidly accelerating, the power output from the engine increases suddenly, and when the friction between the wheels and the ground does not provide enough grip to match such suddenly increasing power demand, some degree of slip of the wheels occurs. When the wheels run on a road surface wet or oil stains, ice and snow and the like are present, the grip ability of the wheels is significantly reduced, and even if the vehicle runs at a normal speed, a certain degree of slip occurs because the wheels cannot obtain sufficient adhesion.

Based on this, in order to ensure that the calculation result of the reference speed of the vehicle is maintained within an acceptable error range, the present embodiment reduces the error influence of the wheel slip on the calculation result of the reference speed by effectively reducing the degree of the wheel slip. In the embodiment of the invention, the first slip quantity and the slip duration of the wheel are acquired respectively, and then the slip condition of the wheel is comprehensively estimated according to the numerical values of the first slip quantity and the slip duration.

It will be appreciated that in some cases, the wheels may only briefly exhibit a slight slip, which has a small effect on the speed of travel of the vehicle and which is able to recover quickly. Based on this, in order to improve the accuracy of the wheel slip degree estimation, the present embodiment avoids considering only the first slip amount of the wheel, but comprehensively considers the slip amount and the slip duration, and can estimate the slip degree of the wheel more accurately from two dimensions of time and distance, thereby improving the comprehensiveness of the wheel slip condition estimation and reducing the possibility of erroneous judgment.

The first slip quantity represents the sliding distance between the wheel and the road surface in unit time, and the slip duration is the duration for which the wheel slides relative to the road surface.

Step S102, controlling wheel braking according to the first slip amount and the slip duration.

In the embodiment of the invention, the slip condition of the wheel can be obtained according to the first slip quantity and the slip duration, and based on the slip condition, in order to reduce the interference of the slip of the wheel on the calculation of the reference speed of the vehicle, the embodiment improves the ground grabbing force of the wheel by controlling the braking of the wheel, thereby reducing the slip of the wheel. It should be noted that, in this embodiment, the braking of the wheel may be dynamically adjusted according to the specific values of the first slip amount and the slip duration, so as to reduce the risk of the wheel losing the grip completely due to sudden or excessive braking, and ensure the safety and controllability of the braking process.

Step S103, during the braking process of the wheels, detecting a second slip amount of the wheels by taking a first preset time as an interval time, wherein the second slip amount and the first slip amount are slip distances of the wheels relative to the ground in unit time at different moments.

In the embodiment of the invention, the second slip quantity of the wheel is periodically detected by spacing the first preset time, so that the continuous monitoring of the slip condition in the wheel braking process is realized. The present embodiment may compare the magnitude relation between the second slip amount and the preset slip threshold value to determine whether braking of the wheel has reduced the slip amount of the wheel to within the acceptable range.

For example, the first preset time is set to 0.01s (second), and the preset slip threshold is set to 2m/s (meters/second) for illustration. During braking, the second slip amount detected at 0.01 seconds is 3m/s, which is greater than the preset slip threshold, and therefore, it is necessary to enter the detection cycle of the next round, and the second slip amount is detected again after an interval of 0.01 seconds, that is, the second slip amount at 0.02 seconds.

And step S104, when the second slip quantity is smaller than or equal to the preset slip threshold value, controlling the wheels to stop braking, and calculating the current reference speed of the vehicle.

In the embodiment of the invention, when the second slip amount is less than or equal to the preset slip threshold value, it is explained that the degree of slip of the wheel has been effectively controlled within the acceptable range by braking the wheel, that is, the influence of the wheel slip on the calculation of the reference speed has been significantly reduced, thereby ensuring that the calculation result of the reference speed can be kept within the allowable error range. At this time, the wheels are controlled to stop braking, and the current reference speed of the vehicle is calculated, and the calculated reference speed of the vehicle based on the current wheel rotation speed tends to the actual speed of the vehicle.

According to the embodiment, the slip degree of the wheels is reduced in advance before the reference speed of the vehicle is calculated, so that the influence of the wheel slip on the reference speed calculation of the vehicle is reduced, the reference speed calculation is calibrated by reducing the influence of the wheel slip on the reference speed calculation, and the accuracy of the reference speed calculation is improved.

Specifically, referring to fig. 2, in the embodiment of the present invention, step S101 includes:

in step S1011, the current longitudinal acceleration and lateral acceleration of the wheel are acquired.

The longitudinal acceleration is the acceleration of the wheel in the direction of travel thereof, and the lateral acceleration is the acceleration of the wheel perpendicular to the direction of travel thereof, i.e. the lateral acceleration. In the embodiment of the invention, the wheel is provided with the acceleration sensor, and the acceleration sensor can continuously acquire the real-time longitudinal acceleration and lateral acceleration of the wheel.

Step S1012, calculating the effective friction coefficient of the wheel based on the longitudinal acceleration and the lateral acceleration.

It will be appreciated that the effective coefficient of friction of a wheel is a parameter that characterizes the relationship between the friction between the wheel and the ground and the positive pressure, which determines the maximum friction that the wheel can produce during travel, while the longitudinal and lateral forces to which the wheel is subjected are provided by the friction between the tyre and the ground. Based on this, the embodiment can calculate the corresponding longitudinal force and lateral force through the longitudinal acceleration and lateral acceleration of the wheel, and then calculate the effective friction coefficient through the longitudinal force and lateral force.

Step S1013, a preset slippage reference set is obtained, wherein the slippage reference set includes a plurality of reference slippage data corresponding to a plurality of effective friction coefficients one by one.

In the embodiment of the invention, corresponding reference slippage data are formulated in advance for different effective friction coefficients, and a slippage reference set is formed by a plurality of reference slippage data. It should be noted that, the correspondence between the effective friction coefficient and the reference slip amount data may be obtained through experimental calculation and test verification in advance, so as to ensure accuracy and reliability of the data.

Step S1014, selecting reference slip data corresponding to the effective friction coefficient from the slip reference set as the first slip.

In one example, the slippage reference set includes three reference slippage data that are, in order, 5m/s, 1m/s, and 0.3m/s, respectively. The three effective coefficients of friction corresponding to this are, in order, 0, 0.3 and 0.8. If the effective friction coefficient calculated from the longitudinal acceleration and the lateral acceleration in this embodiment is 0.3, where 1m/s corresponds to 0.3 in the slip amount reference set, based on this, it is determined that the first slip amount is 1m/s.

With continued reference to fig. 2, in an embodiment of the present invention, step S101 further includes:

In step S1015, when the first slip amount is greater than the preset slip threshold, a third slip amount of the wheel is detected at intervals of a second preset time, where the third slip amount, the first slip amount and the second slip amount are slip distances of the wheel relative to the ground in different moments in unit time.

In the embodiment of the invention, after the first slip amount is determined, whether the slip amount of the wheel is within an acceptable range is judged by comparing the magnitude relation between the first slip amount and the preset slip threshold value. When the first slip amount is less than or equal to the preset slip threshold, it is indicated that the slip amount of the wheel is within an acceptable range without immediately taking braking action. Under this condition, even if the wheels are not braked, the vehicle reference speed calculated based on the wheel speeds of the wheels can also tend to the actual speed of the vehicle, ensuring that even if the wheels slip slightly, unnecessary braking interventions can be avoided, thereby ensuring the running stability of the vehicle and the riding comfort of the passengers.

However, when the first slip amount is greater than the preset slip threshold value, it is indicated that the slip amount of the wheel is beyond the acceptable range, and under this condition, there is a large error between the reference speed of the vehicle calculated based on the wheel speed of the wheel and the actual speed of the vehicle. On the basis, whether the slip condition of the wheels is short slip or not can be continuously judged, so that the accuracy of the assessment of the slip degree of the wheels is improved. Specifically, in the present embodiment, the third slip amount of the wheel is detected by spacing the second preset time, thereby evaluating whether the wheel can end the slip state after the elapse of the second preset time and resume the normal ground attachment force.

Step S1016, when the third sliding quantity is larger than the preset sliding threshold, repeatedly detecting the third sliding quantity by taking the second preset time as interval time, recording the second preset time, and when the third sliding quantity is smaller than or equal to the preset sliding threshold, superposing all the recorded second preset time as sliding time length.

In the embodiment of the present invention, the third slip amount being larger than the preset slip threshold means that the slip condition of the wheel is not a transient slip, based on which it is necessary to determine the slip duration of the wheel. In this embodiment, when the first detected third slip amount is greater than the preset slip threshold, the flow of cycle detection is entered. Specifically, the third slip amount of the wheel is re-detected every second preset time and continuously compared with the preset slip threshold value. And simultaneously, recording the second preset time when each detection is performed until the third slip quantity detected at a certain moment is smaller than or equal to a preset slip threshold value, wherein the sum of all recorded second preset times in the cycle process is the slip duration.

In one example, the preset slip threshold value is set to 2m/s, and the second preset time is set to 0.02s is illustrated. The first detected third slip amount is 4m/s, which is greater than the preset slip threshold, based on which, the third slip amount is detected again after the interval of 0.02s, the third slip amount of 0.04s is 3.5m/s, which is still greater than the preset slip threshold, so the third slip amount is detected again after the interval of 0.02s, the third slip amount of 0.06s is 1.5m/s, which is less than the preset slip threshold, and at this time, the slip duration is 0.06s.

Referring to fig. 3, in an embodiment of the present invention, step S102 includes:

Step S1021, a preset duration threshold is obtained.

Step S1022, when the slip time is longer than the preset time threshold, controlling front wheel braking on the first side in the vehicle and controlling rear wheel braking on the second side in the vehicle.

In the embodiment of the invention, the system is preset with a preset duration threshold value for defining the acceptable range of the wheel slip duration, and it can be understood that when the slip duration is less than or equal to the preset duration threshold value, the wheel slip at the moment is still slip in a short time, belongs to controllable slip, and no braking measures need to be immediately taken. Otherwise, when the slip time length is greater than the preset time length threshold, the fact that the wheel slip at this time has great interference on the calculation of the reference speed of the vehicle is indicated, and the slip degree of the wheel needs to be reduced in advance before the calculation of the reference speed of the vehicle.

Specifically, the present embodiment reduces the degree of slip of the wheels relative to the road surface by controlling front wheel braking on the first side in the vehicle and controlling rear wheel braking on the second side in the vehicle, i.e., controlling the four-wheel drive system of the vehicle to perform diagonal braking. In one example, front wheel braking on the left side of the vehicle may be controlled and rear wheel braking on the right side of the vehicle may be controlled. In another example, front wheel braking on the right side of the vehicle may be controlled and rear wheel braking on the left side of the vehicle may be controlled.

It will be appreciated that this embodiment reduces the likelihood of the other two non-braked wheels losing stability and causing the vehicle to spin out of tail due to lack of sufficient braking force relative to controlling only two front or two rear wheels. Meanwhile, compared with the mode of simultaneously controlling the braking of four wheels, the method reduces the possibility of sideslip of the vehicle in the braking process, can better balance the posture of the vehicle, and improves the controllability and the stability of the vehicle in the braking process.

Specifically, referring to fig. 4, in the embodiment of the present invention, step S1021 includes:

Step S10211, a current vehicle speed of the vehicle is acquired.

In the embodiment of the invention, the current speed of the vehicle is captured and recorded in real time by the central controller, and it can be understood that the force of the driver stepping on the accelerator pedal can be converted into the speed data of the vehicle by the central controller.

Step S10212, based on a preset reference threshold value table, inquiring and acquiring a preset duration threshold value from the reference threshold value table according to the current speed and the effective friction coefficient, wherein the reference threshold value table is used for representing the corresponding relation between the speed of the vehicle and the effective friction coefficient of the wheels.

It can be appreciated that, in the embodiment of the present invention, the reference threshold table may be obtained through experimental calculation and test verification in advance, so as to ensure accuracy and reliability of data. In one example, the current vehicle speed is 10m/s, the effective friction coefficient is 0.30, and the preset duration threshold is 0.40ms (milliseconds) as can be seen in conjunction with FIG. 5. In another example, the current vehicle speed is 35m/s, the effective friction coefficient is 0.30, and the preset duration threshold is 0.30ms as can be seen in conjunction with FIG. 5.

It may be understood that, in the embodiment of the present invention, step S103 further includes:

Step S1031, when the second slip amount is greater than the preset slip threshold, controlling front wheel braking on the second side in the vehicle and controlling rear wheel braking on the first side in the vehicle.

In the embodiment of the present invention, if the first detected second slip amount is greater than the preset slip threshold value during the braking of the wheel, the first braking is not enough to sufficiently inhibit the wheel from sliding, and thus the wheel still needs to be braked continuously. In order to avoid the problem of overheat of the brake system, which may be caused by excessive braking of a single wheel, and thus to cause a reduction in braking performance, the present embodiment controls front wheel braking on the second side in the vehicle and controls rear wheel braking on the first side in the vehicle, even if braking is alternately performed between the two front wheels and between the two rear wheels.

For example, at the time of first braking, front wheel braking on the left side in the vehicle is controlled, and rear wheel braking on the right side in the vehicle is controlled; then on the next braking, the front wheel brake on the right in the vehicle is controlled and the rear wheel brake on the left in the vehicle is controlled, and so on.

Referring to fig. 6, in one example, step S101 includes:

Step S1017, a fourth slip amount of each wheel is acquired, respectively.

In step S1018, the smallest one of all the fourth slip amounts is determined as the first slip amount.

In order to accurately monitor the slip condition of each wheel, in the embodiment of the present invention, the fourth slip amount of each wheel is detected, respectively. Specifically, the smallest one of the total fourth slip amounts is set as the first slip amount to be used as a reference for the subsequent evaluation of the degree of wheel slip, thereby ensuring that braking measures can be timely made to the slipping wheel even if only the individual wheel slips, thereby reducing the influence of the slipping wheel on the reference speed calculation.

Referring to fig. 7, an embodiment of the present invention further provides a vehicle controller 700, which is applied to a four-wheel drive system, the vehicle controller 700 including:

the first detection module 701 is configured to detect a first slip amount and a slip duration of the wheel.

A braking module 702 is configured to control wheel braking based on the first amount of slip and the slip duration.

The second detection module 703 is configured to detect a second slip amount of the wheel with the first preset time as an interval time during braking of the wheel, where the second slip amount and the first slip amount are slip distances of the wheel relative to the ground in different moments in unit time.

An execution module 704 is configured to control the wheels to stop braking and calculate a current reference speed of the vehicle when the second slip amount is less than or equal to a preset slip threshold.

According to the embodiment of the invention, the first slip amount and the slip duration of the wheel are detected through the first detection module 701, the braking of the wheel is controlled through the braking module 702 according to the first slip amount and the slip duration, the second slip amount of the wheel is detected through the second detection module 703 at intervals of a first preset time in the braking process of the wheel, the second slip amount and the first slip amount are slip distances of the wheel relative to the ground in different moments in unit time, the braking of the wheel is stopped when the second slip amount is smaller than or equal to a preset slip threshold value through the execution module 704, the current reference speed of the vehicle is calculated, the slip degree of the wheel is reduced in advance before the calculation of the reference speed of the vehicle is realized, the influence of the slip of the wheel on the calculation of the reference speed of the vehicle is reduced, and the accuracy of the calculation of the reference speed is further improved.

It should be noted that, in the embodiment of the present invention, the first detection module 701 may further perform steps S1011 to S1015 and steps S1017 to S1018 in the above embodiment; the brake module 702 may also perform steps S1021 to S1022 and steps S10211 to S10212 in the above embodiments; the execution module 704 may also execute step S1031 in the above embodiment.

The embodiment of the invention also provides a four-wheel drive system, which is controlled by the calibration method of the vehicle reference speed of the embodiment. In particular, the four-wheel drive system is suitable for various types of vehicles, such as: the present embodiment is not limited to a four-wheel drive car, a four-wheel drive off-road car, or the like.

It can be understood that the four-wheel drive system of the embodiment of the invention controls by applying the calibration method of the vehicle reference speed of the embodiment, and reduces the influence of the wheel slip on the calculation of the vehicle reference speed by reducing the slip degree of the wheels in advance before the calculation of the vehicle reference speed, thereby improving the accuracy of the calculation of the reference speed, providing more accurate data support for the dynamic stability control system and the traction control system of the vehicle, enabling the four-wheel drive system to accurately control based on more accurate vehicle states, improving the ground grabbing performance of the four-wheel drive system, and further improving the running stability and safety of the four-wheel drive system.

The embodiment of the invention also provides a vehicle, which comprises the four-wheel drive system of the embodiment.

Specifically, in the embodiment of the present invention, the vehicle may be a private car, such as a sedan, SUV, MPV, or pick-up card. The vehicle may also be an operator vehicle such as a minibus, bus, minivan or large trailer, etc. The vehicle can be an oil vehicle or a new energy vehicle. When the vehicle is a new energy vehicle, the vehicle can be a hybrid vehicle or a pure electric vehicle.

It can be appreciated that the vehicle of the embodiment of the invention applies the four-wheel drive system of the embodiment, and provides more accurate data support for the dynamic stability control system and the traction control system of the vehicle by improving the accuracy of the calculation of the reference speed of the vehicle, so that the systems can be more effectively intervened, the ground grabbing performance of the four-wheel drive system is enhanced, the operability of the vehicle is improved, the risk of vehicle out of control is reduced, and the stability and the safety in the running process are improved.

The embodiment of the invention also provides electronic equipment, which comprises:

At least one processor;

at least one memory for storing at least one program;

The calibration method of the vehicle reference speed of the above-described embodiment is implemented when at least one program is executed by at least one processor.

The embodiment of the invention also provides a computer readable storage medium, in which a computer program executable by a processor is stored, which when executed by the processor is used to implement the calibration method of the vehicle reference speed of the above embodiment.

The terms "first," "second," "third," "fourth," and the like in the description of embodiments of the invention and in the above-described figures, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the invention described herein may be implemented, for example, in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed or inherent to such process, method, article, or apparatus.

It should be understood that in embodiments of the present invention, "at least one" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.

In the embodiments provided in the present invention, it should be understood that the disclosed system, apparatus and method may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of elements is merely a logical functional division, and there may be additional divisions of actual implementation, e.g., multiple elements or components may be combined or integrated into another system, or some features may be omitted, or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices, or units, which may be in electrical, mechanical, or other forms.

In the present embodiment, the term "module" or "unit" refers to a computer program or a part of a computer program having a predetermined function and working together with other relevant parts to achieve a predetermined object, and may be implemented in whole or in part by using software, hardware (such as a processing circuit or a memory), or a combination thereof. Also, a processor (or multiple processors or memories) may be used to implement one or more modules or units. Furthermore, each module or unit may be part of an overall module or unit that incorporates the functionality of the module or unit.

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

In addition, each functional unit in each embodiment of the present invention may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.

The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the embodiments of the present invention may be essentially or a part contributing to the prior art or all or part of the technical solution may be embodied in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the methods of the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Acce Memory RAM), a magnetic disk, or an optical disk, etc., which can store program codes.

The step numbers in the above method embodiments are set for convenience of illustration, and the order of steps is not limited in any way, and the execution order of each step in the embodiments may be adaptively adjusted according to the understanding of those skilled in the art.

Claims

1. A method of calibrating a reference speed of a vehicle for use in a four-wheel drive system, the method comprising:

Detecting a first slip amount and a slip duration of a wheel;

2. The method of calibrating a reference speed of a vehicle according to claim 1, wherein detecting a first slip amount and a slip duration of a wheel comprises:

3. The method of calibrating a reference speed of a vehicle according to claim 2, wherein detecting a first slip amount and a slip duration of the wheel further comprises:

4. A method of calibrating a vehicle reference speed according to claim 3, wherein the controlling the wheel brake according to the first slip amount and the slip duration comprises:

Acquiring a preset duration threshold;

5. The method according to claim 4, characterized in that the detecting the second slip amount of the wheel at the first preset time interval further comprises:

6. The method for calibrating a vehicle reference speed according to claim 4, wherein the obtaining the preset duration threshold comprises:

Acquiring the current speed of the vehicle;

7. The method of calibrating a reference speed of a vehicle according to claim 1, wherein detecting a first slip amount and a slip duration of a wheel comprises:

respectively obtaining fourth slippage of each wheel;

8. A vehicle controller for use in a four-wheel drive system, the vehicle controller comprising:

9. A four-wheel drive system, characterized in that control is performed using the calibration method of the vehicle reference speed according to any one of claims 1 to 7.

10. A vehicle comprising a four wheel drive system as claimed in claim 9.

11. An electronic device, comprising:

At least one processor;

at least one memory for storing at least one program;

when the at least one program is executed by the at least one processor, the at least one processor is caused to implement the method of calibrating a vehicle reference speed as claimed in any one of claims 1 to 7.

12. A computer readable storage medium having stored therein processor executable instructions, which when executed by a processor are for performing the method of calibrating a vehicle reference speed according to any of claims 1 to 7.