Method for determining tire wear
Patent Information
- Application Number
- FR2022003693
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-04-21
- Publication Date
- 2025-03-07
- Estimated Expiration
- 2042-04-21
Smart Images
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Figure 00000026_0000
Abstract
Description
Title of the invention: Method for determining the wear of a tire Technical field
[0001] The present disclosure relates to the field of measuring tire wear using sensors. Prior art
[0002] The wear of a tire is conventionally measured as the thickness of the tire relative to the bottom of the grooves of this tire. The wear can be measured by means of a wear indicator projecting from the bottom of the groove, this wear indicator being a bead 1.6 mm thick, which corresponds to the value of the legal wear limit of a tire. When the external surface of the tire is at the same height as this bead, this implies that the tire has reached this wear limit value.
[0003] There are also methods for determining the wear of a tire that rely on sensor data, in order to eliminate the need for direct measurement, which also makes it possible to anticipate reaching the wear limit value. When implementing these methods, and even if they do not use a direct measurement of the tire thickness, the degree of wear of the tire is also expressed as a remaining thickness of tire relative to the bottom of a groove.
[0004] For example, methods are known based on measurements of the distance traveled by the tires, from geolocation data, but these methods are not precise since the degree of wear can also vary depending on the condition of the road traveled by the vehicle and the driver's driving profile.
[0005] Also known from document US8,371,159 is a method for estimating the wear of a tire from the processing of measurements made by a radial acceleration sensor mounted on the inner wall of the tire. This method comprises the calculation of a deformation rate of the tire when the area of the tread carrying the sensor reaches the road, from the acceleration measurement provided by the sensor, and the estimation of the degree of wear of the tire from this deformation rate, and from a load applied to the tire, which is itself evaluated using an additional sensor measuring the speed of the wheel. Summary
[0006] The present disclosure provides a reliable, simple method, which can operate as an alternative or complementary method to known methods of estimating the degree of wear of a tire.
[0007] In this regard, there is provided a method for determining the wear of a tire, the method comprising: - obtaining, from measurements of a sensor placed on the internal wall of the tire, a time function of a radial acceleration of the tire tread corresponding to a period of one wheel revolution, - determining, from the radial acceleration time function, an average acceleration value of the radial acceleration over a non-contact portion corresponding to a period in which the section of the tire carrying the sensor is not in contact with a rolling surface of the tire, - the determination of an acceleration extrema value of the time function of the radial acceleration, - the determination of an intermediate acceleration value from the average acceleration value over the non-contact portion and / or the acceleration extrema value, - determining at least one angular position value from the intermediate acceleration value, and - the determination of a tire wear value by implementing, on the determined angular position value, a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values.
[0008] In embodiments, the method comprises: - the determination of a maximum acceleration value B of the radial acceleration, - the determination of an intermediate acceleration value A corresponding to an average between the mean acceleration value and the maximum acceleration value, and - the determination of an angular position value comprising the angular position associated with the intermediate value A.
[0009] In embodiments, the method comprises: - the determination of two intermediate acceleration values comprising the intermediate acceleration value A and an intermediate acceleration value C corresponding to an acceleration value between the average acceleration value and the maximum acceleration value, and - determining two angular position values from the two intermediate acceleration values, the two angular position values corresponding to the angular position values associated with the intermediate acceleration value A and the intermediate acceleration value C.
[0010] In embodiments, the method comprises: - determination of a minimum acceleration value of the radial acceleration, - the determination of an intermediate acceleration value E corresponding to the average between the mean acceleration value and the minimum acceleration value, - the determination of an angular position value including the determination of the angular position associated with the intermediate acceleration value E.
[0011] In embodiments, the method comprises: - the determination of an angular position defining an axis of angular symmetry in a contact portion of the radial acceleration time function corresponding to a substantially constant negative acceleration, and - the determination of two angular position values from an intermediate acceleration value, in which the determination of an angular position value is obtained by symmetry around the axis of angular symmetry from the angular position associated with the intermediate acceleration value.
[0012] In embodiments, the method comprises: - the determination of a maximum acceleration value Bl, - the determination of an intermediate acceleration value C corresponding to an acceleration value between the average acceleration value and the maximum acceleration value Bl, - the determination of an intermediate acceleration value D equal to the average acceleration value, - the determination of an intermediate acceleration value E corresponding to an acceleration value between the average acceleration value and a zero value, - the determination of an angular position associated with the maximum acceleration value Bl, - the determination of an angular position associated with a maximum acceleration value B2 corresponding to a local maximum acceleration of a portion of loss of contact of the radial acceleration time function, - the determination of an angular position associated with the acceleration value intermediate C and included in a range of angular positions associated with a phase of decrease of a portion of contacting of the radial acceleration time function, - the determination of an angular position associated with the intermediate acceleration value C and included in a range of angular positions associated with a growth phase of the loss of contact portion of the radial acceleration time function, - the determination of an angular position associated with the intermediate acceleration value D and included in a range of angular positions associated with the contact portion of the radial acceleration time function, - the determination of an angular position associated with the intermediate acceleration value D and included in a range of angular positions associated with the loss of contact portion of the radial acceleration time function, - determining an angular position associated with the intermediate acceleration value E and included in a range of angular positions associated with the contacting portion of the radial acceleration time function, - determining an angular position associated with the intermediate acceleration value E and included in a range of angular positions associated with the contact loss portion of the radial acceleration time function, in which the angular positions are determined during the acquisition of the sensor measurements making it possible to obtain the radial acceleration time function.
[0013] In embodiments, the function for determining the tire wear value is a regression function.
[0014] A device for determining the wear of a tire is also described, comprising a sensor intended to be arranged on the internal wall of a tire, the sensor being adapted to enable a time function of a radial acceleration of the tread of the tire on a rolling surface to be obtained from measurements of said sensor, and a computer, the device being adapted for implementing the method according to the preceding description.
[0015] Also described is a computer program comprising instructions for implementing a method comprising: - the determination, from a time function of a radial acceleration of the tread of a tire corresponding to a period of one wheel revolution, of an average acceleration value of the radial acceleration over a non-contact portion of the time function corresponding to a period in which the section of the tire carrying the sensor is not in contact with a tire rolling surface, - the determination of an acceleration extrema value of the time function of the radial acceleration, - the determination of an intermediate acceleration value from the average acceleration value on the non-contact portion and the acceleration extrema value, - the determination of an angular position value from the intermediate acceleration value, and - determining a tire wear value by implementing a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values, when this program is executed by a processor.
[0016] Also described is a non-transitory recording medium readable by a computer on which is recorded a program for implementing a method comprising: - determining, from a time function of a radial acceleration of the tread of a tire corresponding to a period of one wheel revolution, an average acceleration value of the radial acceleration over a non-contact portion of the time function corresponding to a period in which the section of the tire carrying the sensor is not in contact with a tread surface of the tire, - the determination of an acceleration extrema value of the time function of the radial acceleration, - the determination of an intermediate acceleration value from the average acceleration value on the non-contact portion and the acceleration extrema value, - the determination of an angular position value from the intermediate acceleration value, and - determining a tire wear value by implementing a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values, when this program is executed by a processor.
[0017] The proposed method makes it possible to determine a degree of wear of a tire with a simplified implementation compared to the state of the art, since the degree wear is determined by applying a determination function, for example a regression function, obtained from a set of tires with varying levels of wear.
[0018] This determination function can be applied directly to one or more characteristic angular position values derived from one or more intermediate acceleration values characteristic of the radial acceleration time function.
[0019] The implementation of this method does not necessarily require the use of an angular position sensor despite the fact that the determination function is based precisely on one or more characteristic angular position values so that this method does not necessarily require the addition of an angular position sensor of the tire to determine the degree of wear of the tire. Brief description of the drawings
[0020] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which: Fig.l
[0021] [Fig.l] schematically represents an example of a sensor positioned on the internal surface of the tread of a tire. Fig. 2
[0022] [Fig.2] schematically represents the main steps of a method according to one embodiment. Fig. 3
[0023] [Fig.3] represents an example of a time function of a radial acceleration of the tread of a tire having several intermediate acceleration values. Fig. 4
[0024] [Fig.4] represents an example of a time function of a radial acceleration of the tread of a tire having several angular positions associated with intermediate acceleration values. Fig. 5
[0025] [Fig.5] represents an example of estimation by regression of the degrees of wear of tires carried out from a set of tires having different degrees of wear and for which characteristic angular position values have been determined. Description of the embodiments
[0026] A method for determining the wear of a tire will now be described, this method being implemented, with reference to [Fig.l], by a device 1 comprising a sensor 10 arranged on the inner wall of the tire, a computer 11 adapted to implement the processing described below on the data acquired by the sensor 10, and a memory 12 storing the code instructions executed by the computer. The computer 11 can for example be of the processor, microprocessor, microcontroller, FPGA, etc. type. The memory The memory 12 can for example comprise a ROM (Read-Only Memory), a RAM (Random Access Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory) or any other type of suitable storage means. The memory can for example comprise optical, electronic or magnetic storage means.
[0027] The sensor 10 may correspond to an acceleration sensor or a shock sensor, for example a piezoelectric type shock sensor. The sensor is adapted to acquire measurements allowing a time function of radial acceleration of the tire to be obtained.
[0028] In this case, the acceleration sensor can be adapted to acquire radial acceleration measurements making it possible to directly obtain the radial acceleration time function of the tire, the radial direction being represented by a dotted line in [Fig.l].
[0029] With regard to the shock sensor, it can be adapted to acquire measurements representing a temporal variation of the radial acceleration of the tire. This temporal variation of the radial acceleration of the tire can make it possible to obtain, by integration, a temporal function of radial acceleration of the tire.
[0030] In [Fig.l], a cross-sectional view of a tire 2 is schematically shown. The tire 2 comprises an internal wall 20 on which the sensor 10 is mounted, a tread 21 which is at all times in contact with the road over a part of its circumference, and which comprises a set of grooves 22 whose depth decreases with the wear of the tread, that is to say that the thickness of the tire from the bottom of a groove decreases with the wear of the tire.
[0031] In examples, the sensor 10 is advantageously positioned in the middle of the width L of the tire, the width being considered in the cross-sectional plane.
[0032] With reference to [Fig. 3], an example of a time function of the radial acceleration ar of the tire tread obtained from measurements of the sensor 10 is shown. The radial acceleration is a periodic function whose period is equal to one wheel revolution, i.e. 360°.
[0033] The radial acceleration time function of [Fig.2] is obtained from a set of measurements of the sensor 10 carried out over a wheel revolution, and which includes a non-contact portion TO in which the variation in radial acceleration is substantially zero. The non-contact portion TO corresponds to the range of angular positions in which the section of the tire carrying the sensor 10 is not in contact with the rolling surface (for example the road). In this case, on the non-contact portion TO, the radial acceleration is approximately Rw2 where R is the radius of rotation of the sensor, and w is the rotation speed of the wheel, assumed to be constant in steady state.
[0034] The time function also comprises a contact portion T1 in which the radial acceleration increases until it reaches a local maximum B1, before decreasing to a substantially zero value. This contact portion T1 corresponds to a range of angular positions during which the section of the tire carrying the sensor comes into contact with the rolling surface. The radial acceleration time function then comprises a contact portion T2 during which the radial acceleration is substantially stabilized at a zero value. This contact portion T2 corresponds to a range of angular positions in which the section of the tire carrying the sensor is in contact with the rolling surface.The time function of the radial acceleration finally includes a loss of contact portion T3 in which the radial acceleration increases up to a second local maximum B2, before decreasing again to approximately Rw2. This portion T3 corresponds to a range of angular positions in which the section of the tire carrying the sensor loses contact with the rolling surface.
[0035] Thus, the portions T1, T2 and T3 represented correspond respectively to variations in radial acceleration induced by contact, contact and loss of contact between the section of tire carrying the sensor and the rolling surface.
[0036] Since the radial acceleration time function is periodic with a period equal to one wheel revolution, angular positions of the wheel can be associated with radial acceleration values measured by the sensor over the wheel revolution.
[0037] The device 1 thus comprises a position / acceleration unit 13 associating an angular position of the tire with a radial acceleration value obtained by the sensor. In examples, the position / acceleration unit 13 can associate angular positions with the radial acceleration values during the acquisition of the measurements allowing the radial acceleration time function to be obtained from the sampling frequency of the sensor 10 and the periods of the previous wheel revolutions. A time difference between two samples can thus be associated with an angular position difference. In other examples, the position / acceleration unit can associate angular positions with radial acceleration values after obtaining a time function of radial acceleration over a complete period.
[0038] In examples, the angular position unit comprises a symmetry unit adapted to determine an angular position defining an axis of angular symmetry S in the contact portion T2 corresponding to a substantially constant zero acceleration. To the extent that the radial acceleration function is periodic and substantially symmetrical around the contact portion T2, a reference angular position can be determined in this contact portion T2 from which other angular positions can be determined.
[0039] The method which is the subject of the present disclosure has the advantage of relying on one or more characteristic angular positions of the radial acceleration time function obtained from measurements of the sensor 10. The use of one or more characteristic angular positions determined from one or more intermediate acceleration values of the radial acceleration time function allows a determination of a tire wear value that is more reliable and more precise than a determination that would be based simply on these intermediate acceleration values or on other acceleration values.
[0040] With reference to [Fig. 2], the main steps of the method for determining tire wear according to a first embodiment are shown schematically. This method comprises obtaining 100, from measurements of the sensor 10, a time function of the radial acceleration of the tire tread. The time function of the radial acceleration is obtained for one wheel revolution. Alternatively, the time function of the radial acceleration can be obtained for several wheel revolutions.
[0041] The method then comprises determining 200, from the time function of the radial acceleration, an average acceleration value A0 of the radial acceleration over the non-contact portion T0 of the radial acceleration time function. As explained previously, the non-contact portion T0 corresponds to an angular period of the time function in which the section of the tire carrying the sensor is not in contact with the rolling surface of the tire. This average acceleration value A0 can be considered for one wheel revolution.
[0042] In cases where the sensor 10 allows a radial acceleration to be obtained for a plurality of wheel revolutions, the determination can be carried out for one or more wheel revolutions for which an acceleration is measured. Furthermore, the average acceleration value A0 determined in step 200 can also correspond to an average of the average accelerations A0 determined for several wheel revolutions.
[0043] The method comprises determining 300 an acceleration extrema value of the radial acceleration time function. In examples, the method may include determining multiple acceleration extrema values.
[0044] An acceleration extrema value of the radial acceleration time function may correspond to a maximum acceleration value illustrated by B1 or B2 in [Fig.2] or to a minimum acceleration value. The minimum acceleration value may be approximated as being equal to 0. Furthermore, when it is the value B2, the maximum acceleration value therefore corresponds to a local maximum.
[0045] The method comprises determining 400 an intermediate acceleration value from the average acceleration value A0 over the non-contact portion T0 and / or the acceleration extrema value. In examples, the method may also comprise determining several intermediate acceleration values.
[0046] The method comprises determining 500 at least one angular position value from the intermediate acceleration value.
[0047] In examples, the angular position value determined at the end of step 500 corresponds to a value of the angular position associated with the intermediate acceleration value determined at the end of step 400. The association of the angular position with the intermediate acceleration value is for example carried out by the position / acceleration unit 13 on the basis of radial acceleration time functions of the previous wheel revolutions or in real time during the acquisition of the measurements from the sensor 10 allowing the obtaining of the radial acceleration time function on which the method is implemented.
[0048] In cases where several intermediate acceleration values are determined, the method may comprise determining several angular position values.
[0049] The method also comprises determining 600 a tire wear value by implementing, on the determined angular position value, a function for determining a tire wear value. The function for determining a tire wear value is determined on a set of tires having different degrees of wear from corresponding angular position test values. By corresponding angular position test values, it is meant angular position test values determined from intermediate acceleration values corresponding to those used later during the method.
[0050] In examples, the method comprises determining several acceleration extrema values. In particular, the method may comprise determining the following values: a maximum acceleration value B1 and a second maximum acceleration value B2, or a maximum acceleration value B1 and a minimum acceleration value, Or - a maximum acceleration value B2 and a minimum acceleration value, or - a maximum acceleration value Bl, a second maximum acceleration value B2 and a minimum acceleration value.
[0051] With reference to Figures 3 and 4, examples of intermediate acceleration values accompanied by their associated angular positions are presented.
[0052] Thus, an intermediate acceleration value may correspond to an intermediate acceleration value A, an intermediate acceleration value B, an intermediate acceleration value C, an intermediate acceleration value D or an intermediate acceleration value E which are developed below. When several intermediate acceleration values are determined, it may be a combination of the intermediate acceleration values A, B, C, D and E.
[0053] In examples, the intermediate acceleration value A corresponds to an acceleration value between the average acceleration value A0 and the maximum acceleration value determined at the end of step 300 when the determined acceleration extrema is a maximum acceleration value. In particular, the intermediate acceleration value A may correspond to an average between the average acceleration value A0 and the maximum acceleration value determined at the end of step 300. Thus, when both the maximum acceleration value B1 and the maximum acceleration value B2 are determined, the method may comprise: - the determination of an intermediate acceleration value Al corresponding to an acceleration value between the average acceleration value A0 and the maximum acceleration value Bl, and / or - the determination of an intermediate acceleration value A2 corresponding to an acceleration value between the average acceleration value A0 and the maximum acceleration value B2.
[0054] In examples, the angular position associated with the intermediate acceleration value A is included in a range of angular positions associated with an increasing phase of the radial acceleration of the contacting portion T1 of the radial acceleration time function. In other examples, the angular position associated with the intermediate acceleration value A is included in a range of angular positions associated with a decreasing phase of the radial acceleration of the contact loss portion T3 of the radial acceleration time function.
[0055] In examples, the angular position aAl associated with the intermediate acceleration value Al is included in a range of angular positions associated with a growth phase of the contacting portion T1. In examples, the angular position aA2 associated with the second intermediate acceleration value A2 is included in a range of angular positions associated with a decrease phase of the contact loss portion T3.
[0056] In examples, the intermediate acceleration value B is equal to the acceleration extrema value determined at the end of block 300. The intermediate acceleration value B may for example be equal to the maximum acceleration value B1, to the maximum acceleration value B2 or the minimum acceleration value of the radial acceleration time function.
[0057] In examples, the angular position associated with the intermediate acceleration value B is included in a range of angular positions of the contacting portion T1, the contact phase T2 or the contact loss portion T3.
[0058] In examples, the angular position aBl associated with an intermediate acceleration value Bl is included in a range of angular positions associated with the contacting portion T1. In examples, the angular position aB2 associated with the intermediate acceleration value B2 is included in a range of angular positions associated with the contact loss portion T3.
[0059] In examples, the intermediate acceleration value C corresponds to an acceleration value between the average acceleration value A0 and the maximum acceleration value determined at the end of step 300. In particular, the intermediate acceleration value C may correspond to an average between the average acceleration value A0 and the maximum acceleration value determined at the end of step 300. Thus, when both the maximum acceleration value B1 and the maximum acceleration value B2 are determined, the method may comprise: - the determination of an intermediate acceleration value Cl corresponding to an acceleration value between the average acceleration value A0 and the maximum acceleration value Bl, and / or - the determination of an intermediate acceleration value C2 corresponding to an acceleration value between the average acceleration value A0 and the maximum acceleration value B2.
[0060] In other examples, the intermediate acceleration value C2 is equal to the intermediate acceleration value Cl.
[0061] In examples, the angular position associated with the intermediate acceleration value C is included in a range of angular positions associated with a decay phase of the radial acceleration of the contacting portion T1 of the radial acceleration time function. In other examples, the angular position associated with the intermediate acceleration value C is included in a range of angular positions associated with a phase of growth of the radial acceleration of the loss of contact portion T3 of the radial acceleration time function.
[0062] In examples, the angular position aCl associated with the intermediate acceleration value Cl is included in a range of angular positions associated with a decreasing phase of the contacting portion T1. In examples, the angular position aC2 associated with the intermediate acceleration value C2 is included in a range of angular positions associated with an increasing phase of the contact loss portion T3.
[0063] In examples, the intermediate acceleration value D corresponds to the average value AO.
[0064] In examples, an angular position aD1 associated with the intermediate acceleration value D corresponds to the angular position of the contacting portion T1 for which the acceleration is equal to the intermediate acceleration value D. In other examples, an angular position aD2 associated with the intermediate acceleration value D corresponds to the angular position of the contact loss portion T3 for which the radial acceleration is equal to the intermediate acceleration value D.
[0065] In examples, the intermediate acceleration value E corresponds to an acceleration value between the average acceleration value and the minimum acceleration value. In examples, the intermediate acceleration value E corresponds to an average between the average acceleration value A0 and the minimum acceleration value.
[0066] In examples, an angular position aEl associated with the intermediate acceleration value E corresponds to the angular position of the contacting portion T1 for which the acceleration is equal to the intermediate acceleration value E. In other examples, an angular position aE2 associated with the intermediate acceleration value E corresponds to the angular position of the contact loss portion T3 for which the radial acceleration is equal to the intermediate acceleration value E.
[0067] In examples, the angular position value determined from the intermediate acceleration value is within an angular position range of the contacting portion T1, the contacting portion T2 or the contact loss portion T3.
[0068] In the examples where several angular position values are determined at the end of step 500 from one or more intermediate acceleration values, the determination function is implemented on the plurality of determined angular position values.
[0069] In examples, the method comprises determining an angular position defining an axis of angular symmetry S in a contact portion T2 of the radial acceleration time function. The contact portion T2 corresponds to a substantially constant zero acceleration of the radial acceleration time function. This step can be implemented from the symmetry unit of the position / acceleration device 13.
[0070] In these examples comprising the determination of an axis of angular symmetry S, the method may comprise the determination of two angular position values from an intermediate acceleration value. The determination of a second angular position value is obtained by angular symmetry around the axis of angular symmetry S from a first angular position value, the latter being associated with the intermediate acceleration value.
[0071] These examples make it possible to avoid calculating the intermediate acceleration values located on one side of the axis of angular symmetry in order to then obtain their associated angular position. In this case, it is a matter of considering that the angular position associated with a second intermediate acceleration value located on one side of the axis of symmetry can be obtained by symmetry from the angular position associated with a first intermediate acceleration value that has been determined and which is located on the other side of the axis of symmetry. It is therefore no longer necessary to determine each of the intermediate acceleration values in order to then determine their associated angular position but to determine a first intermediate acceleration value, its associated angular position and to consider the symmetry of this angular position with respect to the axis of angular symmetry S as being the angular position of a second intermediate acceleration value.
[0072] Thus, the method may comprise determining six angular position values from three intermediate acceleration values. In examples, the method comprises determining six angular position values from the intermediate acceleration value C, the intermediate acceleration value E and the intermediate acceleration value D.
[0073] In a particular example, the method comprises the determination of eight angular position values, these values being determined during the acquisition of the measurements from the sensor 10 making it possible to obtain the radial acceleration time function.
[0074] In this example, the determined acceleration extrema is the maximum acceleration value B1 on the radial acceleration time function.
[0075] The method then determines the following intermediate acceleration values: - an intermediate acceleration value C corresponding to the acceleration value between the average acceleration value and the maximum acceleration value Bl.
[0076] This intermediate acceleration value C can be determined once the acquisition of the maximum acceleration value Bl has been carried out during the acquisition measurements from sensor 10 to obtain the radial acceleration time function. Thus, as soon as the maximum acceleration value B1 is determined, it is possible to calculate the intermediate acceleration value C. - an intermediate acceleration value D corresponding to an acceleration value equal to the average acceleration value AO, - an intermediate acceleration value E corresponding to an acceleration value between the average acceleration value AO and a zero value.
[0077] The average acceleration value AO can be calculated upstream of the determination of the maximum value B1 since a non-contact portion T0 is notably located at this value in time. Thus, the intermediate acceleration values D and E can be determined upstream of the maximum acceleration value Bl.
[0078] The method then determines eight angular position values during the acquisition of the sensor measurements making it possible to obtain the radial acceleration time function: - an angular position aBl associated with the maximum acceleration value BL This is therefore the angular position aBl at which the maximum acceleration value Bl is reached.
[0079] As explained above, the position / acceleration unit 13 can associate angular positions with the radial acceleration values during the acquisition of the measurements allowing the radial acceleration time function to be obtained from the sampling frequency of the sensor 10 and the periods of the previous wheel revolutions. To the extent that the signal is periodic, the person skilled in the art can thus determine a range of angular positions in which the radial acceleration time function will reach its maximum B1 and choose the angular position associated with the highest acceleration value in this range as being the angular position aB1. - an angular position aB2 associated with a maximum acceleration value B2 corresponding to a local maximum acceleration of a portion of loss of contact T3 of the radial acceleration time function.
[0080] In the same way as for aBl, the person skilled in the art can thus determine a range of angular positions in which the radial acceleration time function will reach its local maximum B2 and choose the angular position associated with the highest acceleration value in this range. - an angular position aCl associated with the intermediate acceleration value C and included in a range of angular positions associated with a decrease phase of a contact portion Tl of the radial acceleration time function, - an angular position aC2 associated with the intermediate acceleration value C and included in a range of angular positions associated with a growth phase of the contact loss portion T3 of the radial acceleration time function, - an angular position aDl associated with the intermediate acceleration value D and included in a range of angular positions associated with the contact portion Tl of the radial acceleration time function, - an angular position aD2 associated with the intermediate acceleration value D and included in a range of angular positions associated with the loss of contact portion T3 of the radial acceleration time function, - an angular position aEl associated with the intermediate acceleration value E and included in a range of angular positions associated with the contact portion Tl of the radial acceleration time function, - an angular position aE2 associated with the intermediate acceleration value E and included in a range of angular positions associated with the loss of contact portion T3 of the radial acceleration time function.
[0081] As illustrated in [Fig. 3], the angular positions aCl, aDl, aEl, aE2, aD2, aC2, aB2 are subsequent in time to the acquisition of the measurements by the sensor 10 making it possible to determine the maximum acceleration value Bl. Thus, as soon as this maximum acceleration value Bl has been determined and subject to having also previously determined the average acceleration value AO, it is possible to determine all of the intermediate acceleration values which are associated with the aforementioned angular positions. Indeed, by monitoring the radial acceleration values obtained from the measurements of the sensor 10 as and when its acquisitions are carried out, and by knowing in which range of angular positions to search and which intermediate acceleration values to search, the person skilled in the art can determine each of the angular positions aCl, aDl, aEl, aE2, aD2, and aC2 during the acquisition of the measurements by the sensor 10.This applies in the same way for aB2, as explained above, where the Person Skilled in the Art can for example determine the angular position aB2 as being the angular position associated with the highest acceleration value in a range of angular positions associated with the loss of contact portion T3, this highest value corresponding to the local maximum B2.
[0082] In examples, the time function of the radial acceleration acquired by the sensor covers several wheel revolutions, steps 200 to 600 can be implemented for several wheel revolutions, and an overall wear degree value can be determined. In examples, an overall wear degree value corresponds to an average value of the tire wear values calculated for several iterations. from step 600 of the process over several wheel revolutions.
[0083] In examples, the function for determining the wear value may be a regression function, for example a polynomial function. Alternatively, this function may be a model trained on a learning database comprising, for a set of tires having different degrees of wear, a time function of the radial acceleration of the tread of the tire obtained from a sensor disposed on the inner wall of the tire.
[0084] With reference to [Fig. 5], an example of estimation by regression of degrees of wear is shown, carried out from a set of tires having different degrees of wear and for which characteristic angular position values of the tires have been determined. These characteristic angular position values have been determined from radial acceleration time functions obtained from tires having different degrees of wear. On the abscissa are represented three degrees of tire wear, from left to right: maximum Max, average Med and minimum Min (new tire), and on the ordinate an interval of values of an index based on the characteristic angular position values. This index can be a mathematical transform of a regression equation established using statistical methods of multilinear regression for example.The range of these intervals decreases as the number of measurements used for calculating the index increases.
[0085] The method for determining the wear of a tire according to the present disclosure thus makes it possible to determine a wear value of a tire from obtaining the radial acceleration of a sensor and characteristic angular position values. This method may be an alternative or complementary method to the methods known from the prior art. In this case, in examples, the method for determining the wear of a tire presented, although it relies on one or more angular position values of the tire, cleverly uses the symmetry of the radial acceleration signal over a wheel revolution and the periodicity of the signal to determine the characteristic angular position values so that it does not require the addition of an additional sensor allowing the measurement of the angular position of the wheel during the obtaining of the radial acceleration signal.
Claims
Claims
1. A method for determining the wear of a tire, the method comprising: - obtaining (100), from measurements of a sensor (10) arranged on the inner wall of the tire, a time function of a radial acceleration of the tire tread corresponding to a period of one wheel revolution, - determining (200), from the radial acceleration time function, an average acceleration value (A0) of the radial acceleration over a non-contact portion (T0) corresponding to a period in which the section of the tire carrying the sensor is not in contact with a tread surface of the tire, - determining (300) an acceleration extrema value of the radial acceleration time function,- determining (400) an intermediate acceleration value from the average acceleration value on the non-contact portion (T0) and / or the acceleration extrema value (B1; B2), - determining (500) at least one angular position value from the intermediate acceleration value, and - determining (600) a tire wear value by implementing, on the determined angular position value, a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values.,
2. Method according to the preceding claim, in which the method comprises: - determining a maximum acceleration value B (B1; B2) of the radial acceleration, - determining an intermediate acceleration value A (Al; A2) corresponding to an average between the average acceleration value (AO) and the maximum acceleration value (B1; B2), and - the determination of an angular position value comprising the angular position associated with the intermediate value A.
3. The method of claim 2, wherein the method comprises: - determining two intermediate acceleration values comprising the intermediate acceleration value A (A1; A2) and an intermediate acceleration value C (C1; C2) corresponding to an acceleration value between the average acceleration value (AO) and the maximum acceleration value (B1; B2), and - determining two angular position values from the two intermediate acceleration values, the two angular position values corresponding to the angular position values associated with the intermediate acceleration value A and the intermediate acceleration value C.
4. A method according to any preceding claim, wherein the method comprises: - determining a minimum acceleration value of the radial acceleration, - determining an intermediate acceleration value E (El; E2) corresponding to the average between the average acceleration value and the minimum acceleration value, - determining an angular position value comprising determining the angular position associated with the intermediate acceleration value E.
5. Method according to any one of the preceding claims, wherein the method comprises: - determining an angular position defining an axis of angular symmetry (S) in a contact portion (T2) of the radial acceleration time function corresponding to a substantially constant negative acceleration, and - the determination of two angular position values from an intermediate acceleration value, in which the determination of an angular position value is obtained by symmetry around the axis of angular symmetry (S) from the angular position associated with the intermediate acceleration value.
6. A method according to any preceding claim, wherein the method comprises: - the determination of a maximum acceleration value Bl, - the determination of an intermediate acceleration value C corresponding to an acceleration value between the average acceleration value (AO) and the maximum acceleration value Bl, - the determination of an intermediate acceleration value D equal to the average acceleration value (AO), - the determination of an intermediate acceleration value E corresponding to an acceleration value between the average acceleration value and a zero value, - the determination of an angular position (aBl) associated with the maximum acceleration value Bl, - the determination of an angular position (aB2) associated with a maximum acceleration value B2 corresponding to a local maximum acceleration of a portion of loss of contact (T3) of the radial acceleration time function, - the determination of an angular position (aCl) associated with the intermediate acceleration value C and included in a range of angular positions associated with a decrease phase of a contact portion (Tl) of the radial acceleration time function, - the determination of an angular position (aC2) associated with the intermediate acceleration value C and included in a range of angular positions associated with a growth phase of the loss of contact portion (T3) of the radial acceleration time function, - the determination of an angular position (aDl) associated with the intermediate acceleration value D and included in a range of angular positions associated with the contacting portion (Tl) of the radial acceleration time function, - determining an angular position (aD2) associated with the intermediate acceleration value D and included in a range of angular positions associated with the contact loss portion (T3) of the radial acceleration time function, - determining an angular position (aEl) associated with the intermediate acceleration value E and included in a range of angular positions associated with the contacting portion (Tl) of the radial acceleration time function, - determining an angular position (aE2) associated with the intermediate acceleration value E and included in a range of angular positions associated with the contact loss portion (T3) of the radial acceleration time function,in which the angular positions are determined during the acquisition of the measurements from the sensor (10) making it possible to obtain the radial acceleration time function.,
7. A method according to any preceding claim, wherein the function for determining the tire wear value is a regression function.
8. Device (1) for determining the wear of a tire, comprising a sensor intended to be arranged on the internal wall of a tire, the sensor being adapted to allow obtaining a time function of a radial acceleration of the tread of the tire on a rolling surface from measurements of said sensor, and a calculator (11), the device (1) being adapted for implementing the method according to one of the preceding claims.
9. Computer program comprising instructions for implementing a method comprising: - determining (200), from a time function of a radial acceleration of the tread of a tire corresponding to a period of one wheel revolution, an average acceleration value (AO) of the radial acceleration over a non-contact portion (T0) of the time function corresponding to a period in which the section of the tire carrying the sensor is not in contact with a rolling surface of the tire, - determining (300) an acceleration extrema value (B1; B2) of the time function of the radial acceleration, - determining (400) an intermediate acceleration value from the average acceleration value on the non-contact portion (T0) and the acceleration extrema value (B1; B2), - determining (500) an angular position value from the intermediate acceleration value, and - determining (600) a tire wear value by implementing a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values, when this program is executed by a processor (11).
10. A non-transitory computer-readable recording medium on which is recorded a program for implementing a method comprising: - determining (200), from a time function of a radial acceleration of the tread of a tire corresponding to a period of one wheel revolution, an average acceleration value (A0) of the radial acceleration over a non-contact portion (T0) of the time function corresponding to a period in which the section of the tire carrying the sensor is not in contact with a rolling surface of the tire, - determining (300) an acceleration extrema value (B1; B2) of the time function of the radial acceleration, - determining (400) an intermediate acceleration value from the average acceleration value on the non-contact portion (T0) and the acceleration extrema value (B1; B2), - determining (500) an angular position value at from the intermediate acceleration value, and - determining (600) a tire wear value by implementing a function for determining a tire wear value, the function for determining a tire wear value being determined on a set of tires having different degrees of wear from corresponding angular position test values, when this program is executed by a processor (11).