Method for determining speed of vehicle, computer program product and vehicle

Abstract

The invention provides a method for determining the speed of a vehicle, and the method is characterized in that the method comprises the following steps: an acquisition step: in the acquisition step, current wheel data of wheels of the vehicle are acquired, and the current wheel data comprise tire pressure, tire vertical force and / or tire temperature; a calculation step in which a correction factor representing a relationship between a tire actual size and a tire calibration size of the wheel is calculated on the basis of the current wheel data acquired in the acquisition step; and a determination step in which the speed of the vehicle is determined on the basis of the wheel rotational speed of the wheel, the correction factor determined in the determination step, and the tire calibration size. The application also relates to a corresponding computer program product and a vehicle. The method has the advantage that the speed of the vehicle can be accurately determined all the time under different environmental conditions and vehicle conditions.

Description

Technical Field

[0001] The present application relates to a method for determining the vehicle speed of a vehicle, a computer program product, and a vehicle. Background Art

[0002] A vehicle's speed is typically determined by the wheel speed and the tire circumference under standard conditions (the rated tire circumference). This standard tire circumference is stored as a fixed value in the vehicle. However, during actual driving, tire size varies with tire pressure and vehicle load, and is not a fixed value. Therefore, when the actual tire pressure and vehicle load vary significantly from the standard conditions used to determine the rated tire circumference, there will be a significant error between the theoretical speed calculated using traditional methods and the actual speed. Summary of the Invention

[0003] The object of the present application is to provide a method for determining the vehicle speed of a vehicle, so that the vehicle speed can always be accurately determined under different environmental conditions and vehicle conditions.

[0004] According to a first aspect of the present application, a method for determining a vehicle speed is provided, wherein the method comprises the following steps:

[0005] an acquisition step, in which current wheel data of the wheels of the vehicle are acquired, wherein the current wheel data includes tire pressure, tire vertical force and / or tire temperature;

[0006] an obtaining step, in which a correction coefficient representing a relationship between an actual tire size and a rated tire size of the wheel is obtained based on the current wheel data obtained in the obtaining step;

[0007] A determining step, in which the vehicle speed is determined based on the wheel speed of the wheel, the correction coefficient obtained in the obtaining step, and the rated tire size.

[0008] According to an optional embodiment of the present application, the actual tire size and the rated tire size relate to the tire circumference or tire radius.

[0009] According to an optional embodiment of the present application, the correction coefficient represents the quotient of the actual size of the tire and the rated size of the tire.

[0010] According to an optional embodiment of the present application, the obtaining step includes a first obtaining step, in which a first correction coefficient is obtained based on the tire pressure and tire vertical force obtained in the obtaining step.

[0011] According to an optional embodiment of the present application, the obtaining step includes a second obtaining step, in which a second correction coefficient is obtained based on the first correction coefficient and the tire temperature obtained in the obtaining step.

[0012] According to an optional embodiment of the present application, in the second obtaining step, the first corrected wheel speed corrected by the first correction coefficient is obtained based on the first correction coefficient and the theoretical wheel speed calculated from the tire calibration size and the wheel speed, and the second correction coefficient is obtained based on the first corrected wheel speed and the tire temperature.

[0013] According to an optional embodiment of the present application, the correction coefficient is equal to the first correction coefficient multiplied by the second correction coefficient.

[0014] According to an optional embodiment of the present application, in the obtaining step, the correction coefficient is obtained from a pre-calibrated lookup table based on the current wheel data obtained in the obtaining step.

[0015] According to an optional embodiment of the present application, the lookup table includes a first lookup table, through which a first correction coefficient can be obtained based on the tire pressure and the tire vertical force.

[0016] According to an optional embodiment of the present application, the lookup table includes a second lookup table, through which the second correction coefficient can be obtained based on the first corrected wheel speed and tire temperature corrected by the first correction coefficient.

[0017] According to an optional embodiment of the present application, in the case where the correction coefficient cannot be directly found from the lookup table, an interpolation method is used to obtain the correction coefficient.

[0018] According to an optional embodiment of the present application, in the determining step, the mileage traveled and / or the mileage to be continued of the vehicle is determined based on the determined vehicle speed.

[0019] According to an optional embodiment of the present application, the method includes a judgment step, in which it is judged whether a predetermined condition is met. Only when the predetermined condition is met, the obtaining step and the determining step are performed, and the predetermined condition includes at least one of the following: the sensor of the vehicle for detecting the wheel is not faulty; the electronic stability control function, traction control function, dynamic traction control function, anti-lock braking function and / or vehicle dynamics control function of the chassis control system of the vehicle are not activated; the absolute value of the tire pressure difference between the four wheels of the vehicle is within a set range; the absolute value of the tire vertical force difference between the four wheels of the vehicle is within a set range; the absolute value of the wheel speed difference between the four wheels of the vehicle is within a set range; the slip rate of the wheel is within a set range.

[0020] According to an optional embodiment of the present application, the method includes a control step, in which the vehicle is controlled based on the vehicle speed determined in the determination step.

[0021] According to an optional embodiment of the present application, the wheels include more than two wheels of the vehicle. In the determining step, the wheel speed of each wheel is determined based on the wheel rotation speed of each wheel, the corresponding correction coefficient obtained in the obtaining step, and the corresponding tire calibration size. The vehicle speed is obtained by averaging the wheel speeds of the more than two wheels.

[0022] According to an optional embodiment of the present application, the two or more wheels are two wheels on the front axle or two wheels on the rear axle or four wheels of the vehicle.

[0023] According to a second aspect of the present application, a computer program product is provided, characterized in that it comprises computer program instructions, which implement the aforementioned method for determining the speed of a vehicle when executed by at least one processor.

[0024] According to a third aspect of the present application, a vehicle is provided, characterized in that the vehicle includes a vehicle speed determination module, the vehicle speed determination module includes a processor and a memory, the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the processor is able to execute the aforementioned method for determining the vehicle speed.

[0025] At least in certain embodiments, the present application has the positive effect of ensuring that the vehicle speed can always be accurately determined under different environmental conditions and vehicle conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be described in more detail below with reference to the accompanying drawings, so that the principles, features and advantages of the present invention can be better understood. The accompanying drawings include:

[0027] Figure 1 An example of a vehicle of the present application is schematically shown.

[0028] Figure 2 An example of a wheel of a vehicle is shown schematically.

[0029] Figure 3 An exemplary process of the method for determining the vehicle speed of the present application is schematically shown. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial technical effects to be solved by this application more clearly understood, this application will be further described in detail below with reference to the accompanying drawings and multiple exemplary embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit the scope of protection of this application.

[0031] Figure 1 An example of a vehicle of the present application is schematically shown. The vehicle is particularly a passenger car, but may also be other vehicles such as commercial vehicles. The vehicle has a wheel 1. The wheel 1 is usually equipped with a speed sensor 3 to detect the wheel speed of the wheel 1. In addition, the vehicle also has a vehicle speed determination module 6. In a conventional manner, the vehicle speed determination module 6 calculates the wheel speed of the wheel 1 (hereinafter referred to as the theoretical wheel speed) based on the acquired wheel speed and a pre-stored tire size with a fixed value (or tire nominal size). The theoretical wheel speed Vi can be obtained, for example, according to the following formula:

[0032] Vi=n×C×60 / 1000

[0033] Where Vi is expressed in km / h; n represents the wheel speed in rpm; and C represents the nominal tire size of wheel 1, in this case the nominal tire circumference, in meters. The nominal tire size is generally the tire size at standard pressure and light load.

[0034] Furthermore, the vehicle speed can be determined based on the wheel speeds. It is conceivable to directly use the wheel speed of a single wheel 1 as the vehicle speed. It is also conceivable to average the wheel speeds of multiple wheels 1 to obtain the vehicle speed. The multiple wheels 1 herein can be the two wheels 1 on the front axle, the two wheels 1 on the rear axle, or all four wheels 1 of the vehicle, i.e., two wheels 1 on the front axle and two wheels 1 on the rear axle.

[0035] Figure 2 The schematic diagram shows an example of a wheel 1 of a vehicle. Here, the ideal state 10 of the wheel 1 at the rated tire size is shown by a solid line. In the ideal state 10, the wheel 1 has, for example, a lightly loaded tire rolling radius and a rated tire circumference. The dashed line schematically shows the actual state 11 during actual vehicle driving. Figure 2 In the case of a vehicle with low tire pressure or a heavy load, for example, wheel 1 may have an effective rolling radius that is different from, and in particular, smaller than, its lightly loaded rolling radius, and an actual tire circumference that is different from, and in particular, smaller than, its nominal tire circumference. That is, during actual driving, the actual tire size may vary with tire pressure and vehicle load, resulting in deviations from its nominal tire size.

[0036] from Figure 2As can be seen in the figure, for the same rotation, wheel 1 will have an ideal travel distance of 100 in ideal state 10, while wheel 1 will have an actual travel distance of 110 in actual state 11. These two travel distances deviate. Therefore, determining vehicle speed based solely on the nominal tire size is inaccurate. To obtain a more accurate vehicle speed, the above formula needs to be modified.

[0037] Figure 3 An exemplary process of the method for determining the vehicle speed of the present application is schematically shown.

[0038] like Figure 3 As shown, the method includes the following steps:

[0039] Acquisition step 500, in which current wheel data of wheel 1 of the vehicle is acquired, the current wheel data including tire pressure, tire vertical force and / or tire temperature;

[0040] Obtaining step 504, in which a correction coefficient representing the relationship between the actual tire size and the calibrated tire size of the wheel 1 is obtained based on the current wheel data obtained in the obtaining step 500;

[0041] Determine step 506 , in which the vehicle speed is determined based on the wheel speed of the wheel 1 , the correction coefficient obtained in the determining step 504 , and the tire nominal size.

[0042] The above method makes it possible to always accurately calculate the vehicle speed under different environmental conditions and different vehicle conditions.

[0043] Here, see Figure 1 The tire pressure and tire temperature can be obtained, for example, based on the tire pressure monitoring system 2. The tire vertical force can be obtained, for example, based on the chassis continuous damping control system 4 or through a dedicated sensor.

[0044] For example, the correction factor represents the quotient of the actual tire size and the rated tire size. In this case, the actual wheel speed Va can be calculated according to the following formula:

[0045] Va=n×C×r×60 / 1000, or Va=Vi×r

[0046] Here, r represents a correction factor. Alternatively, the correction factor can be, for example, a difference or the like.

[0047] The actual tire size and the nominal tire size may be related to the tire circumference or tire radius. For example, there is a relationship between the tire circumference C and the tire radius R: C=2πR.

[0048] According to an exemplary embodiment of the present application, the obtaining step 504 includes a first obtaining step, in which a first correction coefficient r1 is obtained based on the tire pressure and the tire vertical force obtained in the obtaining step 500 .

[0049] According to an exemplary embodiment of the present application, the determining step 504 includes a second determining step. In this second determining step, a second correction coefficient r2 is determined based on the first correction coefficient r1 and the tire temperature acquired in the acquiring step 500. Specifically, a first corrected wheel speed Vr1 = Vi × r1, corrected by the first correction coefficient r1, is determined based on the first correction coefficient r1 and a theoretical wheel speed Vi calculated from the nominal tire size and wheel speed. Furthermore, the second correction coefficient r2 is determined based on the first corrected wheel speed Vr1 and the tire temperature. By separating the determining step into the first and second determining steps, the determining steps can be simplified.

[0050] Here, the correction coefficient r is equal to, for example, the first correction coefficient r1 multiplied by the second correction coefficient r2.

[0051] The actual wheel speed Va is

[0052] Va=n×C×r1×r2×60 / 1000, or Va=Vi×r1×r2

[0053] According to an exemplary embodiment of the present application, in the obtaining step 504, a correction coefficient r is obtained from a pre-calibrated lookup table based on the current wheel data obtained in the obtaining step 500. The lookup table may, for example, contain discrete values. If the correction coefficient r cannot be directly obtained from the lookup table, an interpolation method may be used to obtain the correction coefficient.

[0054] In the case of the first and second ascertainment steps, the lookup table may accordingly include a first lookup table and a second lookup table. Compared to a single lookup table, the amount of data contained in the lookup table can be significantly reduced by dividing the lookup table into the first and second lookup tables.

[0055] Exemplarily, the first lookup table is shown in the figure below.

[0056]

[0057] In the first lookup table, the first row represents the tire vertical force in N. The first column represents the tire pressure in bar, where the standard tire pressure is, for example, 2.5 bar. The value in the middle represents the first correction coefficient r1.

[0058] For example, the second lookup table is shown in the following figure:

[0059]

[0060] In the second lookup table, the first row represents the first modified wheel speed Vr1 modified by the first correction coefficient r1, in km / h. The first column represents the tire temperature, in ° C. The value in the middle represents the second correction coefficient r2.

[0061] In order to obtain the lookup table, the present application also relates to a calibration method, for example. The calibration method is implemented, for example, in the following manner:

[0062] a. Place the vehicle on the vehicle chassis dynamometer and set the initial values ​​of r1 and r2 in the first and second lookup tables to 1;

[0063] b. Set the vehicle speed to a steady 30 km / h or 50 km / h. Adjust the vehicle's counterweight and tire pressure based on the values ​​listed in the first lookup table for tire pressure and tire vertical force. Compare the actual vehicle speed value measured on the chassis dynamometer (which corresponds to the actual wheel speed Va) at the corresponding tire vertical force and tire pressure with the theoretical vehicle speed value calculated by the vehicle speed determination module 6 (which corresponds to the theoretical wheel speed Vi) to calibrate the first correction coefficient r1. The calculation formula is as follows:

[0064] r1 = measured vehicle speed / theoretical vehicle speed

[0065] c. After the first correction coefficient r1 in the first lookup table is calibrated, gradually increase the vehicle speed from 30 km / h to the maximum speed on the chassis dynamometer. Based on the tire temperature and the values ​​listed in the second lookup table for the first corrected wheel speed Vr1 after correction by the first correction coefficient r1, compare the corresponding measured vehicle speed values ​​with the theoretical vehicle speed values ​​corrected by the first correction coefficient r1 (which corresponds to the first corrected wheel speed Vr1) to calibrate the second correction coefficient r2. The calculation formula is as follows:

[0066] r2 = measured vehicle speed / theoretical vehicle speed corrected by the first correction coefficient r1

[0067] Instead of using a lookup table, it is conceivable to fit a corresponding functional relationship based on experimental data. In the obtaining step 504, the correction coefficient can be obtained based on such a functional relationship. The advantage of the functional relationship is that no additional interpolation method is required.

[0068] According to an exemplary embodiment of the present application, in determining step 506, the vehicle's mileage and / or range are determined based on the determined vehicle speed. This is useful in some scenarios. For example, a vehicle rental company may need to keep mileage statistics. This approach enables more accurate mileage calculations to be obtained, improving vehicle operational efficiency.

[0069] According to an exemplary embodiment of the present application, Figure 3 As shown, the method includes a judgment step 502, in which it is judged whether a predetermined condition is met. Only when the predetermined condition is met, the obtaining step 504 and the determining step 506 are performed.

[0070] The predetermined condition includes at least one of the following:

[0071] A. The vehicle's sensors for detecting the wheel 1 are normal, including, for example, the speed sensor 3 , the tire pressure sensor and tire temperature sensor of the tire pressure monitoring system 2 , etc.;

[0072] B. the electronic stability control function, traction control function, dynamic traction control function, anti-lock braking function, and / or vehicle dynamics control function of the chassis control system of the vehicle are not activated;

[0073] C. The absolute value of the tire pressure difference between the four wheels 1 of the vehicle (or between any two wheels) is within a set range;

[0074] D. The absolute value of the difference in tire vertical force between the four wheels 1 of the vehicle is within a set range;

[0075] E. The absolute value of the wheel speed difference between the four wheels 1 of the vehicle is within a set range;

[0076] F. The slip ratio of wheel 1 is within the set range.

[0077] In particular, it is conceivable that all of these conditions must be met simultaneously before performing the determination step 504 and the determination step 506. It is conceivable that conditions A and B are used as initial conditions, and only when these initial conditions are met does it determine whether conditions C to F are met. It is conceivable that the method is terminated if any of the conditions is not met.

[0078] According to an exemplary embodiment of the present application, Figure 3As shown, the method includes a control step 508, in which the vehicle is controlled based on the vehicle speed determined in the determination step 506. For example, the vehicle's power system, chassis control system, braking system, battery system, and / or driver assistance system may be controlled based on the determined vehicle speed. Since the vehicle speed is determined more accurately, subsequent vehicle control based on the vehicle speed is more reasonable.

[0079] As long as it is permitted in principle, each of the features listed can be considered to be independent and can be combined with any other features in any form without departing from the scope of protection of this application. If it is permitted in principle, even if not directly mentioned, the features described for one embodiment should be considered to be applicable to other embodiments at will.

[0080] Although specific embodiments of the present application are described in detail herein, they are provided for illustrative purposes only and should not be considered to limit the scope of the present application. Various replacements, changes, and modifications may be conceived without departing from the spirit and scope of the present application.

[0081] Reference Signs List

[0082] 1 wheel

[0083] 10 Ideal State

[0084] 100 ideal moving distance

[0085] 11 Actual Status

[0086] 110 Actual moving distance

[0087] 2. Tire pressure monitoring system

[0088] 3. Speed ​​sensor

[0089] 4Chassis continuous damping control system

[0090] 500 Acquisition Steps

[0091] 502 judgment steps

[0092] 504 steps to obtain

[0093] 506 Determine Steps

[0094] 508 control steps

[0095] 6Vehicle speed determination module

Claims

1. A method for determining the speed of a vehicle, characterized in that The method comprises the following steps: An acquisition step (500), in which current wheel data of a wheel (1) of the vehicle is acquired, wherein the current wheel data includes tire pressure, tire vertical force and / or tire temperature; an obtaining step (504), in which a correction coefficient representing the relationship between the actual tire size and the rated tire size of the wheel (1) is obtained based on the current wheel data obtained in the obtaining step (500); A determination step (506) is provided in which the vehicle speed is determined based on the wheel speed of the wheel (1), the correction coefficient obtained in the obtaining step (504), and the tire nominal size.

2. The method for determining the vehicle speed according to claim 1, characterized in that The actual tire size and the nominal tire size relate to the tire circumference or tire radius; and / or The correction factor represents the quotient of the actual size of the tire and the rated size of the tire.

3. The method for determining the vehicle speed according to claim 1 or 2, characterized in that: The obtaining step (504) includes a first obtaining step, in which a first correction coefficient is obtained based on the tire pressure and the tire vertical force obtained in the obtaining step (500); The obtaining step (504) includes a second obtaining step, in which a second correction coefficient is obtained based on the first correction coefficient and the tire temperature obtained in the obtaining step (500); In the second obtaining step, a first corrected wheel speed corrected by the first correction coefficient is obtained based on the first correction coefficient and a theoretical wheel speed calculated from the rated tire size and the wheel speed, and a second correction coefficient is obtained based on the first corrected wheel speed and the tire temperature. The correction coefficient is equal to the first correction coefficient multiplied by the second correction coefficient.

4. Method for determining the speed of a vehicle according to any one of the preceding claims, characterized in that In the obtaining step (504), a correction coefficient is obtained from a pre-calibrated lookup table based on the current wheel data obtained in the obtaining step (500); The lookup table includes a first lookup table, through which a first correction coefficient can be obtained based on tire pressure and tire vertical force; The lookup table includes a second lookup table, through which a second correction coefficient can be obtained based on a first corrected wheel speed and tire temperature corrected by the first correction coefficient; In the case where the correction coefficient cannot be directly found from the lookup table, an interpolation method is used to obtain the correction coefficient.

5. Method for determining the speed of a vehicle according to any one of the preceding claims, characterized in that In the determining step (506), the mileage and / or the range of the vehicle are determined based on the determined vehicle speed.

6. Method for determining the speed of a vehicle according to any one of the preceding claims, characterized in that The method includes a judgment step (502), in which it is judged whether a predetermined condition is satisfied. The obtaining step (504) and the determining step (506) are performed only when the predetermined condition is satisfied. The predetermined condition includes at least one of the following: The sensor of the vehicle for detecting the wheel (1) is free of faults; The electronic stability control function, the traction control function, the dynamic traction control function, the anti-lock braking function and / or the vehicle dynamics control function of the chassis control system of the vehicle are not activated; The absolute value of the tire pressure difference between the four wheels (1) of the vehicle is within a set range; The absolute value of the difference in tire vertical force between the four wheels (1) of the vehicle is within a set range; The absolute value of the wheel speed difference between the four wheels (1) of the vehicle is within a set range; The slip rate of the wheel (1) is within a set range.

7. Method for determining the speed of a vehicle according to any one of the preceding claims, characterized in that The method includes a controlling step (508) in which the vehicle is controlled based on the vehicle speed determined in the determining step (506).

8. Method for determining the speed of a vehicle according to any one of the preceding claims, characterized in that The wheels (1) include two or more wheels (1) of the vehicle. In the determining step (506), the wheel speed of each wheel (1) is determined based on the wheel speed of each wheel (1), the corresponding correction coefficient obtained in the obtaining step (504), and the corresponding tire calibration size. The vehicle speed is obtained by averaging the wheel speeds of the two or more wheels (1). The two or more wheels (1) are two wheels (1) on the front axle of the vehicle or two wheels (1) on the rear axle or four wheels (1).

9. A computer program product, characterized in that The method comprises computer program instructions which, when executed by at least one processor, implement the method for determining the vehicle speed according to any one of claims 1 to 8.

10. A vehicle, characterized in that: The vehicle comprises a vehicle speed determination module (6), the vehicle speed determination module (6) comprising a processor and a memory, the memory storing computer program instructions, and when the computer program instructions are executed by the processor, the processor is capable of executing the method for determining the vehicle speed according to any one of claims 1 to 8.

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