Apparatus and method for tire wear estimation

Abstract

The present application discloses tire wear estimation. A tire wear estimator (100) includes a tire measurement system adapted to be installed in a tire or on an inner surface of a tire. The tire measurement system includes a sensor (110) adapted to sense physical properties of the tire and an acquisition system (120) adapted to sample the signal of the sensor (110) into a memory (122) to acquire disturbances in the sampled data caused by the contact patch of the tire when the sensor (110) is installed in the tire or on an inner surface of the tire. The sampling rate of the acquisition system (120) is high enough so that at least one oscillation indicative of the tread depth of the tire becomes detectable in the sampled data in and / or around the disturbance.

Description

Technical Field

[0001] The present invention relates to the field of tire mounted sensors (TMS). More particularly, the present invention relates to systems and methods suitable for estimating the wear of a tire. Background Art

[0002] Tire tread depth is critical to automobile safety and having a measurement technique that would enable the car and / or driver to be informed of the tire condition would be of great interest.

[0003] Some prior art solutions for measuring tire tread depth are invasive to the tire.

[0004] Other prior art solutions may be based on rotation counters, for example. However, these solutions may suffer from a lack of accuracy.

[0005] Still other solutions involve contact patch acquisition using accelerometers. One example is disclosed in US8558680B2. In this patent, a method for determining the tread depth of a vehicle tire is disclosed. The method includes: determining the tire contact patch using a sensor located in or on the vehicle tire; and determining the tire revolution time based on the amount of time that a portion of the tire including at least one sensor spends in the tire contact patch.

[0006] Tire mounted sensors are mounted in the tire or on the inner surface of the tire. Figure 1 An example of a tire 200 in which a sensor 110 is mounted is schematically illustrated in FIG. The sensor is mounted at a certain location on the tire 200. During the period of time when the location is part of the contact patch 205 between the tire 200 and the road surface 300, disturbances will occur in the signal generated by the tire mounted sensor.

[0007] The method of US 8558680 B2 comprises determining the tire tread depth as a function of the tire contact patch.

[0008] There exists a need for alternative systems and methods for obtaining an estimate of tire tread depth in a non-invasive manner. Summary of the invention

[0009] It is an object of embodiments of the present invention to provide a good system and method for measuring tire wear in a manner that is non-invasive to the tire.

[0010] The above objects are achieved by the method and device according to the present invention.

[0011] An embodiment of the first aspect of the invention relates to a tire wear estimator comprising a tire measurement system adapted to be mounted in a tire or mounted on an inner surface of a tire. The tire measurement system comprises a sensor adapted to sense a physical property of the tire and an acquisition system adapted to sample the signal of the sensor into a memory. In an embodiment of the invention, the acquisition system is adapted to sample the signal of the sensor such that at least a disturbance in the sampled data caused by the contact patch of the tire when the sensor is mounted in the tire or mounted in the inner surface of the tire is acquired. In an embodiment of the invention, the sampling rate of the acquisition system is high enough such that at least one oscillation indicative of the tread depth of the tire becomes detectable in the sampled data in and / or around the disturbance.

[0012] In an embodiment of the present invention, the tire measurement system may include a communication system for wireless data transmission.

[0013] An advantage of a tire wear estimator according to an embodiment of the present invention is that tire wear can be estimated in a non-intrusive manner. This can be achieved by analyzing disturbances in the sampled data or a processed version of the sampled data.

[0014] In an embodiment of the invention, the sensor is mounted in the tire of the wheel or on the inner surface of the tire of the wheel. The sensor can be completely inherited on the tire (overmolding), or partially overmolded, or attached / bonded to the inner surface, for example.

[0015] In an embodiment of the invention, the tire wear estimator may be adapted to wirelessly transmit the sampled data comprising the at least one oscillation or a processed version of the sampled data.

[0016] The sampled data can be processed directly on the tire measurement system. In that case, it may be that only the resulting tread depth value is transmitted to the vehicle, or even only binary information indicating whether the tread depth is sufficient (OK) or insufficient (KO).

[0017] In other embodiments, the processing of the sampled data may be completed on a separate processing unit. In that case, the sampled data may be transmitted by a communication system.

[0018] In an embodiment of the invention, the sensor is an acceleration sensor.

[0019] In an embodiment of the present invention, the acquisition system includes an analog-to-digital converter for sampling a signal of a sensor.

[0020] In an embodiment of the invention, the tire wear estimator further comprises a processing unit adapted to estimate the tread depth of the tire by analyzing an oscillation of the indication indicative of the tread depth of the tire.

[0021] In an embodiment of the invention, the communication system is adapted to wirelessly transmit the disturbance to the processing unit, and the processing unit is adapted to be located external to the tyre.

[0022] In an embodiment of the invention, the processing unit is adapted to be mounted in the tire or on the inner surface of the tire, and the communication system is adapted to wirelessly transmit the estimated tread depth.

[0023] In an embodiment of the invention, the processing unit is adapted to analyse the amplitude of at least one oscillation to estimate the tread depth.

[0024] In an embodiment of the invention, the processing unit is adapted to analyzing the frequency or period of at least one oscillation to estimate the tread depth.

[0025] In an embodiment of the invention, the sensor is adapted to measure radial acceleration.

[0026] In an embodiment of the invention, the sensor is adapted to measure tangential acceleration.

[0027] In an embodiment of the invention, the acquisition system is adapted to acquire disturbances by storing sampled data in a buffer in a memory until a transmission delay after the disturbance is identified, wherein the disturbance is identified by comparing the stored data with at least one characterizing feature of the disturbance.

[0028] An advantage of embodiments of the present invention is that the first perturbation in the data starting from the moment the sensor system acquires the system will be stored in a buffer by the acquisition system. Thus, faster acquisition is possible compared to systems where at least two sequences need to be acquired to start an acquisition sequence and set up a sleep period. In such prior art systems, multiple acquisitions are synchronized (i.e., specific timings are measured / calculated to ensure proper acquisition of the contact patch).

[0029] In an embodiment of the present disclosure, the characterization features of the disturbance include the leading edge condition and / or the trailing edge condition of the disturbance.

[0030] An embodiment of a second aspect of the present invention relates to a method for estimating tire wear. The method comprises:

[0031] - sampling data from a sensor mounted in the tire or on the inner surface of the tire and adapted to sense a physical property of the tire,

[0032] - fill the buffer with the sampled data,

[0033] - identifying a disturbance in the sampled data, the disturbance being caused when the portion of the tire on which the sensor is mounted strikes the ground,

[0034] The sampling is done at a sampling rate that is high enough so that at least one oscillation indicative of tire tread depth becomes detectable in and / or around a disturbance in the sampled data.

[0035] In embodiments of the invention, sampled data or a processed version of the sampled data may be transmitted comprising at least one oscillation.

[0036] In some embodiments of the invention, at least one oscillation may be transmitted. In other embodiments of the invention, at least one oscillation may be processed and only the result obtained may be transmitted. The result may be, for example, the tread depth, or it may be, for example, binary information indicating whether the tread depth is sufficient (OK) or insufficient (KO).

[0037] In an embodiment of the invention, the tread depth of the tire is estimated by analyzing at least one oscillation in and / or around the disturbance.

[0038] In an embodiment of the invention, identifying the disturbance comprises comparing the data in the buffer with at least one characterizing feature of the disturbance to discover the disturbance in the data.

[0039] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims as appropriate and not only in the manner explicitly set out in the claims but also with features of other dependent claims.

[0040] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram showing a tire in which a sensor is mounted.

[0042] Figure 2 A block diagram of a tire wear estimator adapted for wirelessly transmitting sampled data in and / or around a disturbance is shown according to an embodiment of the present invention.

[0043] Figure 3 A block diagram of a tire wear estimator adapted for wirelessly transmitting a processed version of sampled data in and / or around a disturbance is shown in accordance with an embodiment of the present invention.

[0044] Figure 4 The magnitude of acceleration of a radial acceleration sensor as a function of time according to an embodiment of the invention is shown for a new tire and for a worn tire.

[0045] Figure 5The magnitude of the acceleration of a tangential acceleration sensor as a function of time according to an embodiment of the invention is shown for a new tire and for a worn tire.

[0046] Figure 6 Annular buffering of disturbances of an axial acceleration signal is illustrated according to an embodiment of the present invention.

[0047] Figure 7 Schematic diagram of a circular buffer of disturbances of a tangential acceleration signal according to an embodiment of the present invention.

[0048] Figure 8 A flow chart illustrating an exemplary method according to an embodiment of the present invention in which data may be analyzed and thereafter the analyzed results transmitted.

[0049] Fig. 9 A flow chart showing an exemplary method according to an embodiment of the present invention is shown, in which data is transmitted and may thereafter be analyzed.

[0050] Any reference signs in the claims should not be construed as limiting the scope.

[0051] In the drawings, the same reference numbers refer to the same or similar elements. DETAILED DESCRIPTION

[0052] The present invention is described with reference to specific embodiments and with reference to certain drawings, but the invention is not limited thereto but only by the claims. The drawings described are only schematic and non-limiting. In the drawings, the dimensions of some of the elements may be exaggerated and not drawn to scale for illustrative purposes. The dimensions and relative dimensions do not correspond to actual reductions in the practice of the invention.

[0053] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter; it does not exclude other elements or steps. Therefore, the term is interpreted as specifying the presence of the stated features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Therefore, the scope of the expression "a device comprising means A and B" should not be limited to devices consisting only of components A and B. It means that for the present invention, the only relevant components of the device are A and B.

[0054] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all references to the same embodiment, but may refer to the same embodiment. Furthermore, in one or more embodiments, as will be apparent to one of ordinary skill in the art from this disclosure, the particular features, structures, or characteristics may be combined in any suitable manner.

[0055] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than those expressly recited in each claim. On the contrary, as reflected in the appended claims, the inventive aspects lie in fewer features than all of the features of a single preceding disclosed embodiment. Therefore, the claims appended after the specific embodiment are hereby expressly incorporated into the specific embodiment, with each claim itself representing a separate embodiment of the invention.

[0056] In addition, although some embodiments described herein include some features included in other embodiments but do not include other features included in other embodiments, the combination of features of different embodiments is intended to fall within the scope of the present invention and form different embodiments as will be understood by those skilled in the art. For example, in the appended claims, any of the claimed embodiments may be used in any combination.

[0057] In the description provided herein, numerous specific details are set forth. However, it should be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques are not shown in detail to avoid obscuring an understanding of this description.

[0058] The present invention uses a tire mounted sensor (TMS) of a wheel to estimate the wear of the tire. The sensor is mounted on the inner liner in the tire and is adapted to sense physical properties of the tire. The inventors have discovered that the signal from the sensor during the contact patch can be used to estimate the tread depth. Therefore, the sampling rate at which the accelerometer signal is sampled must be high enough so that at least one oscillation indicative of the tread depth of the tire is detectable in the sampled signal. The inventors have noticed that above a certain frequency, the amplitude and frequency of the at least one oscillation vary with tire wear. The inventors have discovered that when the data is sampled at a sufficiently high sampling rate, at least one oscillation indicative of the tread depth can be monitored around and in the contact patch.

[0059] Embodiments of the first aspect of the present invention relate to a tire wear estimator 100. The tire wear estimator according to an embodiment of the present invention comprises a sensor 110 adapted to sense physical properties of a tire and an acquisition system adapted to sample data of the sensor to acquire disturbances in the sampled data, the disturbances being caused by the contact patch of the tire when the sensor 110 is mounted in or on the inner surface of the tire.

[0060] In an embodiment of the invention, the sampling rate of the acquisition system 120 is high enough so that when the sensor is installed on a new tire, at least one oscillation in and / or around a disturbance indicative of the tread depth of the tire becomes detectable in the sampled data. The at least one oscillation may be caused, for example, by sliding of the tread blocks of the tire while the wheel is turning.

[0061] In an embodiment of the invention, the tire wear estimator 100 may include a communication system 130 for wireless data transmission. The communication system may be used to transmit the sampled data including the at least one oscillation, or to transmit a processed version of the sampled data.

[0062] The sensor may be, for example, an acceleration sensor, an ultrasonic sensor, a piezoelectric sensor, an optical sensor, a magnetic sensor, a deformation sensor or an impact sensor. Different sensors may be combined. The physical property of the tire may be, for example, a dynamic property. For example, an acceleration sensor may be used to measure disturbances.

[0063] In an embodiment of the invention, the tire wear estimator 100 further comprises a processing unit 140 adapted to estimate the tread depth of the tire by analyzing at least one oscillation in the neighborhood of the disturbance having a frequency higher than a characteristic frequency. The characteristic frequency may be tire dependent. Oscillations during the contact patch as well as oscillations just before the contact patch and just after the contact patch may be analyzed. The analysis of the data may be done, for example, in a period before the disturbance, in a period after the disturbance, and during the disturbance. The period depends on the speed of the vehicle. The period may, for example, be at least half of the duration of the footprint. Typically, this may be, for example, 4 ms at 50 km / h. In an embodiment of the invention, the range of the measurement period is, for example, between 1 ms and 30 ms, or even between 4 ms and 15 ms.

[0064] The characteristic frequency may depend on the type of tire. This characteristic frequency may be obtained by calibration for a specific tire. In an embodiment of the invention, the characteristic frequency may be, for example, 200 Hz, or even 400 Hz, or even 800 Hz, or even 1 kHz, or even up to 5 kHz. Without being bound by theory, it is assumed that this frequency depends on the shape and size of the tire blocks.

[0065] Depending on the characteristic frequency, the minimum sampling rate may be selected such that at least one oscillation is detectable in the sampled signal. The acquisition system 120 may, for example, be adapted to sample the sensor 110 at a minimum sampling rate of 400 samples / second, or even 600 samples / second, or even 800 samples / second, or even 1000 samples / second, or even 2000 samples / second, or even 5000 samples / second, or even 7000 samples / second, or even 10000 samples / second, or even 20000 samples / second.

[0066] As discussed in the previous paragraph, the oscillations that depend on the tread depth are tire-dependent and have a frequency of at least 200 Hz. Furthermore, these oscillations only occur just before, during or just after the contact patch. In order to be able to monitor and analyze these oscillations, the sampling rate must be high enough and the contact patch acquisition must be accurate enough.

[0067] In an embodiment of the present invention, an analog-to-digital converter (ADC) may be used to perform data acquisition. The ADC converts an analog signal from a sensor into a digitized signal. The acquisition system samples the data from the analog-to-digital converter and stores it in a buffer. The ADC may, for example, have a resolution between 12 and 18 bits, for example, a resolution of 16 bits.

[0068] exist Figure 2 and Figure 3 A block diagram of different components of a tire wear estimator according to an embodiment of the present invention is shown in FIG.

[0069] exist Figure 2 , a tire wear estimator 100 is shown, wherein a processing unit 140 is adapted to be located outside the tire, the processing unit 140 being adapted to estimate the tread depth of the tire by analyzing at least one oscillation in and / or around the disturbance. In this example, the tire wear estimator 100 comprises a communication system 130 adapted to wirelessly transmit disturbance data to the processing unit 140. In an embodiment of the invention, the engine control unit may be programmed such that it is adapted to estimate the tread depth of the tire by analyzing at least one oscillation in the disturbance according to an embodiment of the invention.

[0070] exist Figure 3 , a tire wear estimator is shown, wherein a processing unit 140 is adapted to be located on the inner surface of the tire, the processing unit 140 being adapted to estimate the tread depth of the tire by analyzing at least one oscillation in and / or around a disturbance. The processing unit 140 may be part of a tire measurement system comprising a sensor 110 and an acquisition system 120. The tire wear estimator comprises a communication system 130 adapted to wirelessly transmit the tread depth.

[0071] The wireless transmission may be, for example, a radio frequency (RF) transmission or a Bluetooth Low Energy (BLE) transmission.

[0072] When a sensor 100 (e.g., an acceleration sensor) according to an embodiment of the present invention is mounted in a tire or mounted on the inner surface of a tire, the sensor 110 will rotate with the tire. The contact between the tire and the ground causes deformation of the tire. The deformation causes additional changes in the measured tire properties (e.g., additional changes in the acceleration of the sensor). Therefore, disturbances will be present in the data from the sensor. The disturbance is caused by the contact patch near the sensor. Collecting sensor data during this contact patch period is also called contact patch acquisition.

[0073] In an embodiment of the present invention, the tread depth is estimated by at least one oscillation on the accelerometer signal during the contact patch. The inventors have observed high frequency oscillations in or around the contact patch period. These oscillations are indicative of the tire tread depth. In order to monitor these oscillations, fast acquisition without moving average is required. The required frequency depends on the tire characteristics. This characteristic frequency can be determined by calibration for a specific type of tire. The relationship between the oscillations and the tread depth can also be determined by calibration for a specific type of tire.

[0074] Figure 4 shows the acceleration of the radial acceleration sensor as a function of time (sample number) ( Figure 1 The amplitude (in arbitrary units) of the acceleration in the z-direction of the sensor. The disturbances in the signal are caused by the contact patch near the sensor. The acceleration is shown for a new tire (2) and for a worn tire (1). In this figure, it can be seen that on the new tire (2) oscillations and the amplitude of the oscillations are higher than on the worn tire (1). The frequency of these oscillations may be in the order of 1 kHz.

[0075] Figure 5 shows the acceleration of the tangential acceleration sensor as a function of time (sample number) ( Figure 1 The amplitude of the oscillation following the trailing edge of the disturbance is higher for the new tire (2) than for the worn tire (1).

[0076] In an embodiment of the invention, the processing unit may be adapted to estimate the tread depth of the tire by analyzing the oscillation period or frequency or amplitude or a combination thereof of the oscillations in and / or around the disturbance. This may be achieved by determining the zero crossings or by calculating a Fast Fourier Transform (FFT). The tread depth may be determined, for example, by a mathematical relationship whose input parameters are the oscillation period or the amplitude. In another embodiment, the period and the amplitude may be combined to form the input parameters of an equation. The equation may be, for example, a linear function or a polynomial function. These functions may be tire-dependent and predefined depending on the tire type.

[0077] In an embodiment of the invention, the sampling rate of the acquisition system may be, for example, higher than the frequency of oscillations indicative of the tread depth of the tire, wherein the oscillations are present in and / or around disturbances in the sampled data. The sampling frequency may be, for example, twice the frequency or higher.

[0078] In an embodiment of the present invention, estimating the tread depth may include fitting the sensor data (e.g., acceleration data) with a model. The model parameters may be specific to the tire. These parameters may be previously calibrated and stored in the tire wear estimator. Depending on where the processing for estimating the tread depth is done, the processing may be in a tire measurement system for being mounted on the innerliner of the tire, or it may be in a processing unit external to the tire.

[0079] In an embodiment of the present invention, the collected data is stored in the memory 122 (see, for example, Figure 2 and Figure 3 The storage may be performed in a buffer in the memory. The buffer may be a circular buffer, also known as a circular table, a ring buffer, or a ring queue. A specific implementation of the ring buffer is, for example, a Ping-Pong buffer or a Bip buffer.

[0080] By comparing the stored data with at least one characteristic feature of the disturbance caused by the contact patch, the acquisition system 120 determines whether a disturbance is present in the data in the buffer. In an embodiment of the present invention, the data is stored in the buffer until a transmission delay after the disturbance in the data is identified. Thus, it is advantageous that the first disturbance after the start of acquisition is acquired. Figure 6 and Figure 7 The possible acquisition of disturbances is illustrated in Figures 1 and 2. Characteristic features of the disturbances can be identified. Therefore, it is possible to acquire the disturbances. In these figures, the oscillations depending on the tire tread depth are not visible. These curves are obtained if the sampling rate is not high enough to monitor the oscillations depending on the tire tread.

[0081] In an embodiment of the invention, the transmission delay may be zero. In an embodiment of the invention, the transmission delay is selected depending on the disturbance duration. It may be, for example, proportional to the disturbance duration. In an embodiment of the invention, the buffer may be a ring buffer. The size of the ring buffer may be such that the data of the disturbance (including the transmission delay and the period before the disturbance) may be stored in the ring buffer. This is Figure 6 In the figure, Figure 6 shows a sequence of disturbances, the first of which is stored in a circular buffer until a propagation delay T after the trailing edge of the disturbance is detected. d At the start time, the tire measurement system according to an embodiment of the present invention wakes up and triggers the acquisition system to acquire data from the sensor. The start of acquisition is indicated by the first vertical dashed line. The transmission delay (T D ) expires, buffering is stopped. This moment is indicated by the second vertical dashed line. In this example, the transmission delay starts from the moment when the trailing edge of the disturbance crosses the trailing edge threshold. The data between the two dashed lines is stored in the (ring) buffer. Figure 6 The two subsequent disturbances in the trajectory in are not sampled by the sensor system (however, this is not necessary). Only after a certain period of time will the sensor system wake up again and acquire new disturbances. By increasing this period of time, the power consumption of the tire measurement system will be reduced. The acquisition system 120 may be adapted to acquire a plurality of these disturbances and to process a plurality of these disturbances. Thus, a better estimate of the tire tread depth may be obtained.

[0082] Figure 7 A diagram showing a disturbance caused by a contact patch generated by an accelerometer sensitive to tangential acceleration, wherein the disturbance is identified by means of peak detection. Tangential acceleration vs. Figure 1 The acceleration along the x-axis corresponds to the acceleration along the x-axis in the measured data. In this exemplary embodiment, the disturbance is identified by detecting the second peak. The characterizing feature can be, for example, a threshold for determining the second peak or an expected shape of the second peak that can be related to the measured data. In an embodiment of the present invention, the disturbance can be identified by detecting the first peak and the second peak. In that case, the characterizing feature is related to the first peak and the second peak. When the delay expires after the disturbance is identified, the acquisition is stopped.

[0083] In an embodiment of the present invention, the acquisition system continuously fills the buffer with data until the disturbance is identified by comparing the data with at least one characteristic feature of the disturbance. The leading edge and the trailing edge of the contact patch can be detected, for example, in the (ring) buffer (for example, when the disturbance is a pulse with a leading edge and a trailing edge). In that case, the characteristic features of the disturbance include the leading edge condition and / or the trailing edge condition of the disturbance related to the occurrence of the contact patch. These leading edge conditions and / or trailing edge conditions can be, for example, thresholds. The leading edge can be detected, for example, when the data crosses a predefined leading edge threshold, and the trailing edge can be detected when the data crosses a trailing edge threshold. When the leading edge and the trailing edge are determined, the disturbance is present in the buffer. The leading edge can be, for example, a falling edge, and the trailing edge can be, for example, a rising edge. Other features of the disturbance (such as, peak values) can be used to identify the disturbance. Peak detection can be used, for example, in the case of a sensor that generates a tangential acceleration signal.

[0084] In an embodiment of the invention, comparing the stored data to at least one characteristic feature of the disturbance may include processing the data. The processing may, for example, include performing a Fast Fourier Transform (FFT) on the data. In that case, the at least one characteristic feature of the disturbance is a characteristic feature of the processed data (e.g., an edge or peak in the processed data).

[0085] In an embodiment of the present invention, the sensor system 100 is adapted to enter a low power mode between multiple disturbance acquisitions. In such a sensor system 100, the sensor system wakes up and triggers the acquisition system to acquire data from the sensor. The acquisition system is adapted to acquire data and to store the data in a buffer. In the case of a circular buffer, the buffer can be implemented, for example, by filling a circular table until the end of the table, after which the circular table is filled from the beginning. In general, a circular buffer can be implemented in the following manner: fill the buffer until the buffer is full, and thereafter overwrite the oldest sample with the latest sample. This process is continued until a disturbance in the data caused by a ground trace is detected in the circular table (e.g., until a leading edge and a trailing edge are detected in the data, or until a peak is detected in the data, or any other characteristic feature of the disturbance).

[0086] As described above, the acquisition system may wait for a transmission delay to ensure that the complete footprint is acquired (this is an optional feature). This delay may, for example, depend on the duration of the footprint-related disturbance (T patch ).

[0087] After acquiring the disturbance and transmitting the at least one oscillation or a processed version of the at least one oscillation, the tire wear estimator enters a sleep mode, resulting in reduced power consumption.

[0088] The tire measurement system according to an embodiment of the invention may be battery powered. Alternatively, an energy harvester may be used to power the tire measurement system. It is advantageous for the tire wear estimator to enter a sleep mode after transmitting at least one oscillation or a processed version of at least one oscillation, as this will result in reduced power consumption.

[0089] An embodiment of a second aspect of the present invention relates to a method 400 for estimating tire wear. Figure 8 and Fig. 9 A flow chart of an exemplary method according to an embodiment of the present invention is shown in FIG.

[0090] The method according to an embodiment of the present disclosure comprises step 412 of sampling data of a sensor 110 which is mounted in the tire or on the inner surface of the tire and which is adapted to sense physical properties of the tire. When sampling the data, a buffer is filled 414 with the sampled data.

[0091] When the portion of the tire where the sensor is mounted hits the ground, this causes a disturbance in the sampled data. The method according to an embodiment of the invention is adapted to identify 415 this disturbance in the sampled data. Data around the disturbance (i.e., before the start of the disturbance and / or after the end of the disturbance) may be collected.

[0092] In an embodiment of the invention, sampling 412 is done at a sufficiently high sampling rate that at least one oscillation indicative of tire tread depth becomes detectable in and / or around a disturbance in the sampled data.

[0093] The method according to an embodiment of the invention may comprise transmitting 420 the sampled data or a processed version of the sampled data, the sampled data comprising at least one oscillation indicative of tire tread depth.

[0094] In an embodiment of the invention, sampling 412 of data may be accomplished, for example, at a sampling rate of at least 200 samples / second.

[0095] In an embodiment of the invention, the method further comprises: estimating the tread depth of the tire by analyzing 419 at least one oscillation in and / or around the disturbance. This can be done on a processing unit located outside the tire, or it can be done on a processing unit located in the tire or on the inner surface of the tire. In the first case, the disturbance data (see Fig. 9 ) and analyze the transmitted data, and in the latter case, transmit 420 the analyzed 419 data (see Figure 8 ).

[0096] In an embodiment of the invention, identifying 415 a disturbance includes comparing 416 the data in the buffer with at least one characteristic feature of the disturbance to discover 418 the disturbance in the data.

Claims

1. A tire wear estimator (100), comprising a tire measurement system, the tire measurement system being adapted to be installed in a tire or on an inner surface of a tire, the tire measurement system comprising a sensor (110) and an acquisition system (120), the sensor (110) being adapted to sense a physical property of the tire, wherein the sensor is an acceleration sensor, the acquisition system (120) being adapted to sample a signal of the sensor (110) into a memory (122) to acquire a disturbance in the sampled data caused by a contact patch of the tire, wherein: The sampling rate of the acquisition system (120) is high enough so that a plurality of oscillations become detectable in the sampled data in and / or around the disturbance, wherein the plurality of oscillations are indicative of a tread depth of the tire, and wherein the frequency of the plurality of oscillations is above a characteristic frequency, and wherein the characteristic frequency is tire dependent.

2. The tire wear estimator (100) according to claim 1, the measurement system further comprising a communication system (130) for wireless data transmission.

3. The tire wear estimator (100) according to claim 1, the acquisition system comprising an analog-to-digital converter for sampling the signal of the sensor (110).

4. The tire wear estimator (100) according to claim 1, further comprising a processing unit (140), wherein the processing unit (140) is adapted to estimate the tread depth of the tire by analyzing the plurality of oscillations indicating the tread depth of the tire.

5. The tire wear estimator (100) according to claim 4, the measurement system further comprising a communication system (130) for wireless data transmission, wherein: The communication system (130) is adapted to wirelessly transmit the disturbance to the processing unit (140), and wherein the processing unit (140) is adapted to be located externally of the tire.

6. The tire wear estimator (100) according to claim 4, the measuring system further comprising a communication system (130) for wireless data transmission, wherein: The processing unit (140) is adapted to be mounted in the tire or on the inner surface of the tire, and wherein the communication system (130) is adapted to wirelessly transmit the estimated tread depth.

7. The tire wear estimator (100) according to claim 4, wherein: The processing unit (140) is adapted to analyze the amplitude of the plurality of oscillations to estimate the tread depth, and / or wherein the processing unit (140) is adapted to analyze the frequency or period of the plurality of oscillations to estimate the tread depth.

8. The tire wear estimator (100) according to claim 1, wherein: The sensor (110) is adapted to measure radial acceleration.

9. The tire wear estimator (100) according to claim 1, wherein: The sensor (110) is adapted to measure tangential acceleration.

10. The tire wear estimator (100) according to claim 1, wherein: The acquisition system (120) is adapted to acquire the disturbance by storing the sampled data in a buffer in a memory (122) until a transmission delay after the disturbance is identified, wherein the disturbance is identified by comparing the stored data with at least one characteristic feature of the disturbance.

11. The tire wear estimator (100) according to claim 10, wherein: The at least one characterizing feature of the disturbance comprises a leading edge condition and / or a trailing edge condition of the disturbance.

12. A method (400) for estimating tire wear, the method comprising: sampling (412) data from a sensor (110) which is an accelerometer sensor and which is mounted in the tire or on the inner surface of the tire and which is adapted to sense a physical property of the tire, filling (414) a buffer with the sampled data, identifying (415) a disturbance in the sampled data, the disturbance being caused when the portion of the tire where the sensor is mounted strikes the ground, wherein the sampling (412) is performed at a sampling rate high enough so that a plurality of oscillations become detectable in the sampled data in and / or around the disturbance, wherein the plurality of oscillations are indicative of a tread depth of the tire, and wherein a frequency of the plurality of oscillations is above a characteristic frequency, and wherein the characteristic frequency is tire dependent.

13. The method of claim 12, further comprising transmitting (420) the sampled data or a processed version of the sampled data, the sampled data comprising the plurality of oscillations.

14. The method (400) of claim 12, further comprising: A tread depth of the tire is estimated by analyzing (419) the plurality of oscillations in and / or around the disturbance.

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