阅读说明：本技术 轮胎纵向力的估测方法、装置、电子设备和存储介质 (Method and device for estimating longitudinal force of tire, electronic device and storage medium ) 是由 赵通 危银涛 梁冠群 杜永昌 童汝亭 于 2021-06-11 设计创作，主要内容包括：本发明提供一种轮胎纵向力的估测方法、装置、电子设备和存储介质,所述轮胎纵向力的估测方法包括：获取待估测轮胎的垂向力和所述待估测轮胎滚动时内壁的周向加速度；根据所述内壁的周向加速度获取所述待估测轮胎的周向变形二阶梯度的峰值差；将所述周向变形二阶梯度的峰值差和所述待估测轮胎的垂向力,输入至预设的轮胎纵向力估测模型,得到所述待估测轮胎的纵向力；所述预设的轮胎纵向力估测模型是以所述样本轮胎的周向变形二阶梯度的峰值差和所述样本轮胎的垂向力为自变量,以所述样本轮胎的纵向力为因变量,基于多组试验标定数据进行拟合得到的。本发明的技术方案可以提高轮胎的纵向力的估测准确度和实时性。(The invention provides a method and a device for estimating tire longitudinal force, electronic equipment and a storage medium, wherein the method for estimating tire longitudinal force comprises the following steps: acquiring the vertical force of a tire to be estimated and the circumferential acceleration of the inner wall of the tire to be estimated when the tire rolls; obtaining the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables. The technical scheme of the invention can improve the estimation accuracy and real-time performance of the longitudinal force of the tire.)

1. A method of estimating a longitudinal force of a tire, comprising:

acquiring a vertical force of a tire to be estimated and a circumferential acceleration of an inner wall of the tire to be estimated when the tire to be estimated rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at a midpoint position of the inner wall of the tire to be estimated in the transverse direction;

obtaining the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall;

inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated;

the preset tire longitudinal force estimation model is obtained by fitting based on multiple groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of a sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as a dependent variable.

2. The method for estimating a longitudinal force of a tire according to claim 1, wherein the fitting process of the tire longitudinal force estimation model includes:

under the condition of different vertical forces of the sample tires, measuring the corresponding longitudinal force of the sample tires and collecting the circumferential acceleration of the inner walls of the sample tires to obtain the multiple groups of test calibration data;

obtaining the peak value difference of the second-order gradient of circumferential deformation of the sample tire according to the circumferential acceleration of the inner wall of the sample tire;

and fitting based on multiple groups of test calibration data to obtain the tire longitudinal force estimation model by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

3. The method for estimating a longitudinal force of a tire according to claim 1 or 2, wherein the obtaining a peak difference of a second order gradient of circumferential deformation of the tire to be estimated from the circumferential acceleration of the inner wall comprises:

dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotating speed of the tire to be estimated to obtain a circumferential deformation second-order gradient;

and subtracting the absolute values of the circumferential deformation second-order gradient at the grounding front edge and the grounding rear edge to obtain the peak value difference of the circumferential deformation second-order gradient.

4. The method for estimating a tire longitudinal force according to claim 1 or 2, wherein the tire longitudinal force estimation model includes:

F_x＝k·Δp+b(F_z)；

wherein, F_xIs the longitudinal force of the tire, k, b are the parameters to be fitted, F_zThe vertical force of the tire is adopted, and the delta p is the peak value difference of the circumferential deformation second-order gradient; and b is related to the vertical force of the tire, and the peak difference of the tire longitudinal force and the circumferential deformation second-order gradient is in a linear relation.

5. The method for estimating a longitudinal force of a tire according to claim 1, wherein the fitting based on a plurality of sets of test calibration data to obtain the tire longitudinal force estimation model using the peak difference of the second order gradient of circumferential deformation of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as a dependent variable comprises: and fitting by using the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables based on a plurality of groups of test calibration data by using a least square method to obtain the tire longitudinal force estimation model.

6. The method for estimating a longitudinal force of a tire according to claim 1, wherein before obtaining the vertical force of the tire to be estimated and the circumferential acceleration of the inner wall of the tire during rolling, the method further comprises:

and measuring the circumferential acceleration of the inner wall of the tire to be estimated by adopting a micro-electro-mechanical system (MEMS) acceleration sensor.

7. The method for estimating a longitudinal force of a tire according to claim 1, wherein before dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotation speed of the tire to be estimated, the method further comprises:

acquiring the rotating speed of the tire to be estimated measured by the wheel speed sensor; alternatively, the first and second electrodes may be,

and acquiring the rotating speed of the tire to be estimated according to the circumferential acceleration of the inner wall of the tire to be estimated and a first time length, wherein the first time length is obtained by timing the time of one rotation of the tire to be estimated.

8. An apparatus for estimating a longitudinal force of a tire, comprising:

the device comprises a first acquisition unit, a second acquisition unit and a control unit, wherein the first acquisition unit is used for acquiring the vertical force of a tire to be estimated and the circumferential acceleration of the inner wall of the tire to be estimated when the tire to be estimated rolls, and the circumferential acceleration is measured by an acceleration sensor arranged at the midpoint of the transverse direction of the inner wall of the tire to be estimated;

the second acquisition unit is used for acquiring the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall;

the estimation unit is used for inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated;

the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

9. An electronic device comprising a memory, a processor and a computer program stored on said memory and executable on said processor, characterized in that said processor, when executing said program, carries out the steps of the method for estimating a longitudinal force of a tire according to any one of claims 1 to 7.

10. A non-transitory computer-readable storage medium, on which a computer program is stored, wherein the computer program, when being executed by a processor, implements the steps of the method for estimating a longitudinal force of a tire according to any one of claims 1 to 7.

Technical Field

The present invention relates to the field of vehicle engineering technologies, and in particular, to a method and an apparatus for estimating a tire longitudinal force, an electronic device, and a storage medium.

Background

Accurate estimation of tire force has been a subject of intense research in the field of vehicle engineering. In recent years, with the development of sensor technology, a method of monitoring tire parameters by mounting a sensor in a tire has received much attention. The sensor signals are processed by a specific algorithm to obtain various parameter information related to the tire and the road surface.

The tire longitudinal force is a key variable of a dynamic control system such as an anti-lock braking system, automatic emergency braking and the like, and the safety performance of vehicle safety control can be enhanced by accurately estimating and monitoring the longitudinal force. Most current methods for estimating the longitudinal force of the tire need to fuse signals of a plurality of sensors in the tire, rely on complex tire models, and need large calculation amount to realize real-time estimation.

There is a need for a real-time and accurate method for estimating the longitudinal force of a tire.

Content of application

The invention provides a tire longitudinal force estimation method, a tire longitudinal force estimation device, electronic equipment and a non-transitory computer readable storage medium, which are used for solving the defect that the tire longitudinal force is difficult to estimate in the prior art and accurately estimating the tire longitudinal force.

In a first aspect, the present invention provides a method for estimating a longitudinal force of a tire, comprising: acquiring a vertical force of a tire to be estimated and a circumferential acceleration of an inner wall of the tire to be estimated when the tire to be estimated rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at a midpoint position of the inner wall of the tire to be estimated in the transverse direction; obtaining the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

According to the invention, the method for estimating the longitudinal force of the tire is provided, and the fitting process of the tire longitudinal force estimation model comprises the following steps: under the condition of different vertical forces of the sample tire, measuring the corresponding longitudinal force of the sample tire and collecting the circumferential acceleration of the inner wall of the sample tire to obtain the multiple groups of test calibration data; obtaining the peak value difference of the second-order gradient of circumferential deformation of the sample tire according to the circumferential acceleration of the inner wall of the sample tire; and fitting based on multiple groups of test calibration data to obtain the tire longitudinal force estimation model by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

According to the method for estimating the longitudinal force of the tire provided by the invention, the step of obtaining the peak difference of the second-order gradient of the circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall comprises the following steps: dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotating speed of the tire to be estimated to obtain a circumferential deformation second-order gradient; and subtracting the absolute values of the circumferential deformation second-order gradient at the grounding front edge and the grounding rear edge to obtain the peak value difference of the circumferential deformation second-order gradient.

According to the present invention, there is provided a tire longitudinal force estimation method, wherein the tire longitudinal force estimation model includes: f_x＝k·Δp+b(F_z) (ii) a Wherein, F_xIs the longitudinal force of the tire, k, b are the parameters to be fitted, F_zThe vertical force of the tire is adopted, and the delta p is the peak value difference of the circumferential deformation second-order gradient; and b is related to the vertical force of the tire, and the peak difference of the tire longitudinal force and the circumferential deformation second-order gradient is in a linear relation.

According to the method for estimating the tire longitudinal force provided by the invention, the tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables, and comprises the following steps: and fitting by using the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables based on a plurality of groups of test calibration data by using a least square method to obtain the tire longitudinal force estimation model.

According to the method for estimating the longitudinal force of the tire provided by the invention, before the vertical force of the tire to be estimated and the circumferential acceleration of the inner wall of the tire to be estimated during rolling are obtained, the method further comprises the following steps: and measuring the circumferential acceleration of the inner wall of the tire to be estimated by adopting a micro-electro-mechanical system (MEMS) acceleration sensor.

According to the present invention, before dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotation speed of the tire to be estimated, the estimation method further comprises: acquiring the rotating speed of the tire to be estimated measured by the wheel speed sensor; or obtaining the rotation speed of the tire to be estimated according to the circumferential acceleration of the inner wall of the tire to be estimated and a first time length, wherein the first time length is obtained by timing the time of one rotation of the tire to be estimated.

In a second aspect, the present invention also provides a tire longitudinal force estimation device, including: the device comprises a first acquisition unit, a second acquisition unit and a control unit, wherein the first acquisition unit is used for acquiring the vertical force of a tire to be estimated and the circumferential acceleration of the inner wall of the tire to be estimated when the tire to be estimated rolls, and the circumferential acceleration is measured by an acceleration sensor arranged at the midpoint of the transverse direction of the inner wall of the tire to be estimated; the second acquisition unit is used for acquiring the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; the estimation unit is used for inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

According to the tire longitudinal force estimation device provided by the invention, the tire longitudinal force estimation device can further comprise a fitting unit; the first acquisition unit is also used for measuring the corresponding longitudinal force of the sample tire and acquiring the circumferential acceleration of the inner wall of the sample tire under the condition of different vertical forces of the sample tire to obtain the multiple groups of test calibration data; the second acquisition unit is further used for acquiring the peak value difference of the second-order gradient of the circumferential deformation of the sample tire according to the circumferential acceleration of the inner wall of the sample tire; the fitting unit is used for fitting based on multiple groups of test calibration data to obtain the tire longitudinal force estimation model by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

According to the estimation device of the tire longitudinal force provided by the invention, the second obtaining unit is further used for dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotating speed of the tire to be estimated to obtain a circumferential deformation second-order gradient; and subtracting the absolute values of the circumferential deformation second-order gradient at the grounding front edge and the grounding rear edge to obtain the peak value difference of the circumferential deformation second-order gradient.

In a third aspect, the present invention further provides an electronic device, comprising a memory, a processor and a computer program stored in the memory and operable on the processor, wherein the processor executes the program to implement the steps of the method for estimating the longitudinal force of a tire as described in any one of the above.

In a fourth aspect, the present invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program which, when executed by a processor, performs the steps of the method for estimating the longitudinal force of a tire as described in any one of the above.

According to the tire longitudinal force estimation method, the tire longitudinal force estimation device, the electronic equipment and the non-transitory computer readable storage medium, the circumferential acceleration is obtained by measuring the circumferential acceleration of the inner wall of the tire, the peak difference of the circumferential deformation second-order gradient of the tire is further obtained, and the peak difference and the tire vertical force are input into a preset tire longitudinal force estimation model to obtain the tire longitudinal force, so that the tire longitudinal force can be accurately estimated in real time.

Furthermore, the technical scheme of the invention adopts a plurality of groups of experimental calibration data to fit the tire longitudinal force estimation model, and when the tire longitudinal force is estimated, under the condition of the known tire vertical force, the real-time longitudinal force estimation can be realized only by acquiring the circumferential acceleration signal of the inner wall when the tire rolls, carrying out corresponding processing and inputting the signal into the preset tire longitudinal force estimation model; the method has the advantages of no need of complex and expensive equipment, higher reliability and estimation precision, and capability of providing longitudinal force information for vehicle safety and comfort control.

Drawings

In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a schematic flow chart of a method for estimating a longitudinal force of a tire according to the present invention;

FIG. 2 is a schematic diagram of a tire longitudinal force estimation system according to the present invention;

FIG. 3 is a schematic diagram of a circumferential acceleration signal of an inner wall of the tire as it rolls provided by the present invention;

FIG. 4 is a schematic diagram of the relationship between the peak difference of the circumferential deformation second order gradient of the tire under different vertical forces and the longitudinal force provided by the present invention;

FIG. 5 is a schematic structural diagram of an apparatus for estimating a longitudinal force of a tire according to the present invention;

fig. 6 is a schematic structural diagram of an electronic device provided in the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.

Fig. 1 is a flowchart illustrating a method for estimating a longitudinal force of a tire according to an embodiment of the present invention. The method provided by the embodiment of the invention can be executed by any electronic equipment with computer processing capability, such as a terminal device and/or a server. As shown in fig. 1, the method for estimating the tire longitudinal force includes:

102, acquiring the vertical force of the tire to be estimated and the circumferential acceleration of the inner wall of the tire to be estimated when the tire rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at the midpoint of the inner wall of the tire to be estimated in the transverse direction.

Specifically, the circumferential acceleration refers to an acceleration in the circumferential direction of the inner wall of the tire to be estimated. The lateral direction refers to a direction perpendicular to a plane on which one circumference of the tire to be estimated lies, and the position of the midpoint disposed in the lateral direction of the inner wall of the tire to be estimated refers to the position of the acceleration sensor disposed at any point on the circumference formed by the lateral midpoint of the inner wall of the tire to be estimated. The acceleration sensor measures the circumferential acceleration and outputs the circumferential acceleration. The electronic device that executes the method of estimating the tire longitudinal force acquires the circumferential acceleration in step 102.

And 104, acquiring a peak value difference of a second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall.

Specifically, the gradient of the circumferential deformation of the tire surface refers to the rate of change of the circumferential deformation of the tire surface, and the second-order gradient of the circumferential deformation of the tire surface refers to the rate of change of the circumferential deformation of the tire surface. The peak value of the second order gradient of the circumferential deformation includes the second order gradient of the circumferential deformation at the ground contact leading edge and the ground contact trailing edge positions of the tire, and the peak difference refers to the difference value of the second order gradient of the circumferential deformation at the ground contact leading edge and the ground contact trailing edge positions of the tire.

And 106, inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated.

Specifically, the vertical force of the tire to be estimated refers to the pressure perpendicular to the ground or slope to which the tire is subjected.

The preset tire longitudinal force estimation model is obtained by fitting based on multiple groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as a dependent variable.

In the technical scheme provided by the embodiment of the invention, a plurality of groups of experimental calibration data are adopted to fit the tire longitudinal force estimation model, and when the tire longitudinal force is estimated, the real-time longitudinal force estimation can be realized only by acquiring circumferential acceleration signals of the inner wall of the tire during rolling, carrying out corresponding processing and inputting the signals into the preset tire longitudinal force estimation model; the method has the advantages of no need of complex and expensive equipment, higher reliability and estimation precision, and capability of providing longitudinal force information for vehicle safety and comfort control.

Specifically, fitting refers to connecting a series of points on a plane with a smooth curve. In the embodiment of the invention, a least square curve fitting method can be adopted to carry out fitting based on a plurality of groups of test calibration data.

The least square method, also known as the least squares method, is a mathematical optimization technique. It finds the best functional match of the data by minimizing the sum of the squares of the errors. Unknown data can be easily obtained by the least square method, and the sum of squares of errors between these obtained data and actual data is minimized. The least squares method may be used for curve fitting.

Specifically, given a set of measurement data, a functional relationship f (x, a) between the variables x and y is found based on the least squares principle, such that it best approximates or fits the known data. f (x, A) is called the fitting model and is some of the parameters to be determined. This is done by selecting the parameter a such that the weighted sum of squares of the residuals at each point of the fitted model and the actual observed values is minimal. Wherein, the residual means the difference between the actual observed value and the fitting value in the mathematical statistics. The curve fitted using this method is called the least squares fit curve.

The least squares method is the most common method to solve the curve fitting problem. In one embodiment, the basic idea of the least squares method is:

wherein the content of the first and second substances,is a pre-selected set of linearly independent functions, a_kIs the undetermined coefficient (k 1, 2, …, m, m < n), and the fitting criterion is such that y_i(i-1, 2, …, n) and f (x)_i) The sum of the squares of the distances of (a) is minimal, which is referred to as the least squares criterion.

Solving the fitting curve by the least square method requires determining a fitting model f (x), which is a tire longitudinal force estimation model in the embodiment of the present invention, and may be: f_x＝k·Δp+b(F_z) (ii) a Wherein, F_xIs the longitudinal force of the tire, k, b are the parameters to be fitted, F_zThe vertical force of the tire is adopted, and the delta p is the peak value difference of the circumferential deformation second-order gradient; b is related to the vertical force of the tire, and the peak difference of the second-order gradient of the tire longitudinal force and the circumferential deformation is in a linear relation.

Here, the fitting process of the tire longitudinal force estimation model includes: firstly, under the condition of different vertical forces of a sample tire, measuring the longitudinal force of the corresponding sample tire and collecting the circumferential acceleration of the inner wall of the sample tire to obtain a plurality of groups of test calibration data. And then, acquiring the peak value difference of the second-order gradient of the circumferential deformation of the sample tire according to the circumferential acceleration of the inner wall of the sample tire. And finally, fitting based on multiple groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables to obtain a tire longitudinal force estimation model.

The multiple groups of test calibration data can be obtained by performing a bench test on a tire flat plate test bed. Under the test condition, the slip rate and the vertical force of the tire are changed, and the circumferential acceleration and the longitudinal force of the inner wall of the tire under each working condition are respectively measured by using an instrument, so that the required test calibration data can be obtained. Specifically, different slip ratios mean different circumferential acceleration peak differences, and a wider range of data can be obtained by adopting different slip ratio conditions of the tire.

For the above tire longitudinal force estimation model, the longitudinal force in the multiple sets of test calibration data is taken as F_xTaking the peak value difference of the second-order gradient of circumferential deformation obtained from the circumferential acceleration in the multi-group test calibration data as delta p, and fitting by adopting a least square method to obtain parameters k and b (F)_z) Then, the tire longitudinal force estimation model can be obtained through fitting. The fitted tire longitudinal force estimation model can be used for real-time tire longitudinal force estimation.

Although the least square method is used for fitting to obtain the tire longitudinal force estimation model in the embodiment of the present invention, the fitting method is not limited thereto.

In an embodiment of the present invention, before step 102, a MEMS acceleration sensor may be used to measure the circumferential acceleration of the inner wall of the tire to be estimated.

The MEMS (Micro-Electro-Mechanical System) acceleration sensor has the advantages of small volume, low energy consumption and capability of bearing severe working environment in the tire, and can acquire an acceleration signal without changing the characteristics of the tire.

FIG. 2 is a schematic diagram of a tire longitudinal force estimation system according to the present invention. As shown in fig. 2, a tire longitudinal force estimation system may be established based on the acceleration sensor 202. The system comprises an upper computer and a lower computer.

The lower computer includes an acceleration sensor 202 and a lower computer processor 204, and the upper computer includes an upper computer processor 206 and a memory 208.

Specifically, the acceleration sensor 202 and the lower computer processor 204 may be disposed at a midpoint position in the lateral direction of the inner wall of the tire. The acceleration sensor 202 and the lower computer processor 204 may be disposed on the same printed circuit board.

In addition, wireless communication modules (not shown in the figure) can be arranged in the upper computer and the lower computer respectively to carry out wireless communication between the upper computer and the lower computer. In some embodiments, the wireless communication module may be integrated in the upper computer processor and the lower computer processor.

In one embodiment, the lower machine may be wrapped with a rubber sleeve. And then, fixing the rubber sleeve wrapped with the lower computer at the middle point of the inner wall of the tire in the transverse direction by using an adhesive.

An acceleration sensor 202 in the lower computer acquires a circumferential acceleration signal of the inner wall of the tire when the tire rolls and sends the circumferential acceleration signal to a lower computer processor 204, and the lower computer processor 204 sends the circumferential acceleration signal to the upper computer through a built-in wireless communication module or an external wireless communication module.

In the upper computer, the upper computer processor 206 is configured to receive a circumferential acceleration signal sent by the lower computer through a built-in wireless communication module or an external wireless communication module, and estimate a longitudinal force applied to the tire according to the circumferential acceleration signal and a preset longitudinal force estimation model. The memory 208 is used to store algorithm programs, various models such as a longitudinal force estimation model, and signal data.

The tire longitudinal force estimation system provided by the embodiment of the invention can realize real-time longitudinal force estimation only by acquiring circumferential acceleration signals of the inner wall of the tire when the tire rolls; the method has the advantages of no need of complex and expensive equipment, higher reliability and estimation precision, and capability of providing longitudinal force information for vehicle safety and comfort control.

FIG. 3 is a schematic diagram of a circumferential acceleration signal of an inner wall of a tire during rolling according to an embodiment of the present invention. As shown in fig. 3, when the acceleration sensor is about to enter the ground contact area, a peak of acceleration in a negative direction is generated due to a squeezing action of the tire surface in the circumferential direction; in the central position of the grounding area, the acceleration sensor and the ground do not move relatively, and the circumferential acceleration is zero; when the acceleration sensor is about to leave the contact patch, a positive acceleration peak is generated due to the stretching action of the tire surface in the circumferential direction. The acceleration peak locations correspond to the leading and trailing edge locations of the ground.

The acceleration sensors arranged on the inner wall of the tire roll along with the tire, and during the transition between the grounding and non-grounding of the tire, the circumferential acceleration signal changes sharply, and the sharp changes correspond to the turning positions of the leading edge and the trailing edge of the grounding of the tire.

In step 104, dividing the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotation speed of the tire to be estimated to obtain a circumferential deformation second-order gradient; and subtracting the absolute values of the circumferential deformation second-order gradient at the grounding front edge and the grounding rear edge to obtain the peak value difference of the circumferential deformation second-order gradient.

In step 104, before dividing the circumferential acceleration of the inner wall by the square of the rotation speed of the tire to be estimated, the rotation speed of the tire to be estimated needs to be obtained, and specific obtaining methods thereof may include, but are not limited to, the following two methods.

The first one is: and acquiring the rotating speed of the tire to be estimated measured by the wheel speed sensor.

The second method is as follows: and acquiring the rotating speed of the tire to be estimated according to the circumferential acceleration of the inner wall of the tire to be estimated and a first time length, wherein the first time length is obtained by timing the time of one rotation of the tire to be estimated.

The embodiment of the invention explains an acceleration generation mechanism according to a tire rolling kinematic model, and the acceleration generation mechanism provides effective theoretical guidance for tire longitudinal force estimation. With the method of describing the rolling deformation of a tire using hybrid Euler-Lagrange, the tire surface circumferential acceleration can be expressed as:

a_u＝Ω²-u″；

wherein, a_uFor circumferential acceleration, omega for wheel speedU' is a second order gradient of circumferential deformation of the tire surface, and the mechanism links the tire surface deformation and the acceleration, and provides theoretical support for developing tire parameter estimation application based on the acceleration sensor.

When a tire longitudinal force is present, the deformation form of the tire surface changes in the circumferential direction of the tire surface in the ground contact region. In particular, the contact patch tire surface is biased in the longitudinal force direction relative to the wheel center location, thereby causing a second order gradient of tire surface deformation at the leading and trailing edge contact locations. Therefore, the tire longitudinal force can be estimated by the change of the second order gradient of the deformation of the tire surface at the ground contact leading edge and trailing edge positions.

The embodiment of the invention provides a mechanism for influencing the deformation of the surface of the tire by the longitudinal force of the tire, and the mechanism is combined with the mechanism for generating the circumferential acceleration of the tire to disclose the relationship between the peak difference of the second-order gradient of the circumferential deformation and the longitudinal force.

The tire flexible ring model can describe tire surface deformation caused by distribution of tire contact area force, the tire flexible ring model is solved under the working condition of applying different longitudinal forces, circumferential deformation under different tire longitudinal forces can be obtained, and circumferential acceleration under different tire longitudinal forces can be obtained by combining a circumferential acceleration expression. Meanwhile, the vertical force of different tires can also affect the deformation of the tire surface.

Fig. 4 is a relationship between a peak difference of a circumferential deformation second-order gradient and a longitudinal force under different vertical forces, which is provided in the embodiment of the present invention, and as shown in fig. 4, the peak difference of the circumferential deformation second-order gradient and the longitudinal force are in a linear relationship under the same vertical force; the slope of the relationship line is the same under different vertical forces, but there is a distance, so the relationship between the peak difference of the circumferential deformation second order gradient and the longitudinal force can be expressed as: f_x＝k·Δp+b(F_z) (ii) a Wherein, F_xIs the longitudinal force of the tire, k, b are the parameters to be fitted, F_zThe vertical force of the tire is adopted, and the delta p is the peak value difference of the circumferential deformation second-order gradient; b is related to the vertical force of the tire, and the peak difference of the second-order gradient of the longitudinal force and the circumferential deformation of the tire is in a linear relation.

The above expression is a tire longitudinal force estimation model, which describes how to estimate the longitudinal force from the circumferential acceleration signal in a simple linear form.

In actual use, the vertical force can be measured by the wagon balance, and can also be estimated by utilizing an acceleration sensor and a related algorithm.

According to the method for estimating the longitudinal force of the tire, the circumferential acceleration is obtained by measuring the circumferential acceleration of the inner wall of the tire, the peak difference of the second-order gradient of the circumferential deformation of the tire is further obtained, and the peak difference and the vertical force of the tire are input into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire, so that the longitudinal force of the tire can be accurately estimated in real time.

The following describes the tire longitudinal force estimation device provided by the present invention, and the tire longitudinal force estimation device described below and the tire longitudinal force estimation method described above can be referred to in correspondence with each other.

FIG. 5 is a schematic structural diagram of an apparatus for estimating a longitudinal force of a tire according to the present invention. As shown in fig. 5, the estimation apparatus of the tire longitudinal force according to the embodiment of the present invention includes:

the first obtaining unit 502 is configured to obtain a vertical force of the tire to be estimated and a circumferential acceleration of the inner wall of the tire to be estimated during rolling, where the circumferential acceleration is measured by an acceleration sensor disposed at a midpoint of the inner wall of the tire to be estimated in a lateral direction.

A second obtaining unit 504, configured to obtain a peak difference of a second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall of the tire to be estimated.

The estimation unit 506 is configured to input the peak difference of the second-order gradient of circumferential deformation and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain a longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on multiple groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

In the technical scheme provided by the embodiment of the invention, a plurality of groups of experimental calibration data are adopted to fit the tire longitudinal force estimation model, and when the tire longitudinal force is estimated, the real-time longitudinal force estimation can be realized only by acquiring circumferential acceleration signals of the inner wall of the tire during rolling, carrying out corresponding processing and inputting the signals into the preset tire longitudinal force estimation model; the method has the advantages of no need of complex and expensive equipment, higher reliability and estimation precision, and capability of providing longitudinal force information for vehicle safety and comfort control.

The tire longitudinal force estimation model may be: f_x＝k·Δp+b(F_z) (ii) a Wherein, F_xIs the longitudinal force of the tire, k, b are the parameters to be fitted, F_zThe vertical force of the tire is adopted, and the delta p is the peak value difference of the circumferential deformation second-order gradient; b is related to the vertical force of the tire, and the peak difference of the second-order gradient of the tire longitudinal force and the circumferential deformation is in a linear relation.

For the above tire longitudinal force estimation model, the longitudinal force in the multiple sets of test calibration data is taken as F_xTaking the peak value difference of the second-order gradient of circumferential deformation obtained from the circumferential acceleration in the multi-group test calibration data as delta p, and fitting by adopting a least square method to obtain parameters k and b (F)_z) Then, the tire longitudinal force estimation model can be obtained through fitting. The fitted tire longitudinal force estimation model can be used for real-time tire longitudinal force estimation.

The device for estimating the longitudinal force of the tire provided by the embodiment of the invention further comprises a fitting unit.

Specifically, the first obtaining unit 502 is further configured to measure a longitudinal force of the corresponding sample tire and collect a circumferential acceleration of an inner wall of the sample tire under conditions of different vertical forces of the sample tire, so as to obtain multiple sets of test calibration data.

The second obtaining unit 504 is further configured to obtain a peak difference of a second order gradient of circumferential deformation of the sample tire according to the circumferential acceleration of the inner wall of the sample tire.

The fitting unit is used for fitting the tire longitudinal force estimation model based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

The second obtaining unit 504 is further configured to divide the circumferential acceleration of the inner wall of the tire to be estimated by the square of the rotation speed of the tire to be estimated, so as to obtain a circumferential deformation second-order gradient; and subtracting the absolute values of the circumferential deformation second-order gradient at the grounding front edge and the grounding rear edge to obtain the peak value difference of the circumferential deformation second-order gradient.

The fitting unit is further used for fitting by using the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables based on a plurality of groups of test calibration data and by using a least square method to obtain a tire longitudinal force estimation model.

It can be understood that the estimation device for longitudinal force of tire described above can realize the steps of the estimation method for longitudinal force of tire provided in the foregoing embodiments, and the related explanations regarding the estimation method for longitudinal force of tire are applicable to the estimation device for longitudinal force of tire, and will not be described herein again.

According to the tire longitudinal force estimation device provided by the embodiment of the invention, the circumferential acceleration is obtained by measuring the circumferential acceleration of the inner wall of the tire, the peak difference of the circumferential deformation second-order gradient of the tire is further obtained, and the peak difference and the vertical force of the tire are input into the preset tire longitudinal force estimation model to obtain the longitudinal force of the tire, so that the longitudinal force of the tire can be accurately estimated in real time.

Fig. 6 illustrates a physical structure diagram of an electronic device, which may include, as shown in fig. 6: a processor (processor)610, a communication Interface (Communications Interface)620, a memory (memory)630 and a communication bus 640, wherein the processor 610, the communication Interface 620 and the memory 630 communicate with each other via the communication bus 640. The processor 610 may invoke logic instructions in the memory 630 to perform a method of estimating a longitudinal force of a tire, the method comprising: acquiring a vertical force of a tire to be estimated and a circumferential acceleration of an inner wall of the tire to be estimated when the tire to be estimated rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at a midpoint position of the inner wall of the tire to be estimated in the transverse direction; acquiring the peak value difference of a second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on multiple groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

In addition, the logic instructions in the memory 630 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to 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 (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.

In another aspect, the present invention also provides a computer program product comprising a computer program stored on a non-transitory computer-readable storage medium, the computer program comprising program instructions which, when executed by a computer, enable the computer to perform a method for estimating a longitudinal force of a tire provided by the above methods, the method comprising: acquiring a vertical force of a tire to be estimated and a circumferential acceleration of an inner wall of the tire to be estimated when the tire to be estimated rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at a midpoint position of the inner wall of the tire to be estimated in the transverse direction; obtaining the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

In yet another aspect, the present invention also provides a non-transitory computer-readable storage medium having stored thereon a computer program, which when executed by a processor, is implemented to perform the method for estimating the longitudinal force of a tire as provided above, the method comprising: acquiring a vertical force of a tire to be estimated and a circumferential acceleration of an inner wall of the tire to be estimated when the tire to be estimated rolls, wherein the circumferential acceleration is measured by an acceleration sensor arranged at a midpoint position of the inner wall of the tire to be estimated in the transverse direction; obtaining the peak value difference of the second-order gradient of circumferential deformation of the tire to be estimated according to the circumferential acceleration of the inner wall; inputting the peak value difference of the circumferential deformation second-order gradient and the vertical force of the tire to be estimated into a preset tire longitudinal force estimation model to obtain the longitudinal force of the tire to be estimated; the preset tire longitudinal force estimation model is obtained by fitting based on a plurality of groups of test calibration data by taking the peak difference of the circumferential deformation second-order gradient of the sample tire and the vertical force of the sample tire as independent variables and the longitudinal force of the sample tire as dependent variables.

The above-described embodiments of the apparatus are merely illustrative, and 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 modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will 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; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.