Determining tire mileage of a tire using an acceleration sensor mounted to the tire

Abstract

A method for tire mileage determination of a tire includes measuring, by an acceleration sensor mounted to the tire, acceleration in a radial direction of the tire in one or more acceleration measurements, and calculating, by a computing component, a reference acceleration for a reference speed. Wherein the reference speed includes a speed in a list of predetermined speeds, the calculating includes obtaining the reference acceleration by discretely integrating an initial value for each reference speed, and the reference speed and the reference acceleration are integers. The method further includes determining a tire speed based at least in part on the measured acceleration and the reference acceleration.

Description

1. Technical Field

[0001] This invention relates to a method for determining tire mileage for a tire. Specifically, the invention provides: (i) a first method aimed at measuring the tire's radial acceleration in one or more acceleration measurements using an acceleration sensor mounted to the tire; and (ii) a second method aimed at calculating a reference acceleration and determining the tire speed based at least in part on the measured acceleration and the reference acceleration. 2. Background Technology

[0002] Common tire mileage estimation and / or measurement components can be configured to determine and / or measure the same tire mileage for all tires mounted on the same vehicle. However, there are common scenarios where such components and / or methods introduce significant errors in determining the actual tire mileage of a particular tire. Exemplary scenarios include, for example, truck driving conditions where a particular tire may be replaced, and / or, for example, when the truck is traveling without a load, one or more tires may be lifted off the road. In such driving conditions, for example, the front and rear tires travel approximately the same distance, yet the middle tire that may be lifted off the road at this time does not accumulate tire mileage at all.

[0003] Generally speaking, tire mileage does not always correspond to the mileage of the tractor unit of a vehicle. Therefore, it may be advantageous to determine tire mileage specifically for each individual customer. Otherwise, these significant errors in the determined tire mileage can hinder sound decision-making, such as determining when or whether tires need to be replaced. Using installed sensors to calculate the mileage of individual tires allows information about the history of that individual tire to be retained even when it is removed and reassembled on a different vehicle (e.g., a trailer).

[0004] Possible approaches to this include mounting individual sensors to individual tires. For example, US 2014 / 107946 A1, US 2011 / 066397 A1, US 2014 / 107946 A1, US 2021 / 260937 A1, and WO 2020 / 038675 A1 relate to methods and apparatus for determining tire mileage or tire wear using tire-mounted acceleration sensors, for example, based on these tire-mounted acceleration sensors.

[0005] However, known methods and apparatus have several drawbacks: First, their accuracy and reliability can still be further improved. Second, complex tire mileage or tire wear estimation / determination procedures may require external components (e.g., remote servers or vehicle-mounted devices) to perform the procedure or at least a portion thereof. This increases complexity, cost, and potential start-up and / or maintenance work.

[0006] Therefore, there remains a need for further improvements to the methods, devices, and systems used for tire mileage determination. 3. Summary of the Invention

[0007] The various aspects of the present invention at least partially satisfy the above-mentioned needs.

[0008] A first aspect of the invention relates to a method for determining tire mileage for a tire. The method includes measuring the tire's radial acceleration by an acceleration sensor mounted to the tire in a measurement sequence comprising two or more acceleration measurements, wherein a first acceleration measurement and a second acceleration measurement are time-separated by a measurement sequence time T. seq Among them, T seq Less than the predetermined maximum driving speed v max Tire rotation time T rev And T seq A portion of the tires is greater than the predetermined minimum driving speed v min Contact imprint time T between the bottom and the ground cp .

[0009] Regarding the second aspect, the inventors understand that while an ideal, non-deformable tire would only generate centrifugal acceleration on the sensor, a real tire experiences deformation on the portion of the tire that contacts the surface on which the vehicle is traveling (referred to herein as the "road") (referred to as the "contact imprint"). This deformation can be viewed by the sensor as a Z-axis accelerometer signal superimposed on the centrifugal acceleration. Since it is desirable to measure only the tire's centrifugal acceleration in order to convert that centrifugal acceleration into wheel speed, it is convenient to measure radial acceleration at least twice within the measurement sequence. Therefore, the time difference between the two acceleration measurements (measurement sequence time T) seq The time interval can be selected to be greater than the maximum contact imprint time to ensure at least one acceleration measurement when the accelerometer is not located in the contact imprint area. For the same reason, this time interval should be shorter than the predetermined maximum travel speed v. max The next rotation time T rev .

[0010] In an example of a vehicle tire with an average radius of approximately 0.5 m (circumference of approximately 3.2 m), a contact imprint length of approximately 5% of the circumference can be observed. If a minimum detectable speed of 15 km / h is desired, this corresponds to a rotation time of approximately 770 ms and a contact imprint time of approximately 38 ms.

[0011] If we want the maximum detectable speed of a vehicle to be 90 km / h, this corresponds to approximately 128 ms of rotation time and approximately 7 ms of contact imprint time for the same wheel. In this case, choosing a time interval between 38 ms (i.e., the maximum contact imprint time) and 128 ms (the minimum rotation time) ensures that at least one measurement is outside the contact imprint. Generally, the terms "speed" and "velocity" are used interchangeably in this document.

[0012] Therefore, the method of the present invention provides a simple and efficient way to ensure that tire mileage determination is based on unaltered acceleration measurements by eliminating contact imprint-related effects that would significantly alter acceleration measurements. This improves the efficiency, reliability, and / or accuracy of acceleration measurement and / or tire mileage determination.

[0013] An acceleration sensor (also known as an accelerometer) may include a device designed to measure the acceleration experienced by a subject. In this document, acceleration refers to the rate of change of velocity, which can occur in different directions and magnitudes.

[0014] Exemplary embodiments of accelerometers may include one or more of the following: Piezoelectric accelerometers: This type of accelerometer utilizes the piezoelectric effect to measure acceleration, wherein a piezoelectric crystal generates an electric charge when subjected to mechanical stress, the charge being proportional to the applied acceleration. In a variation of this piezoelectric accelerometer, a piezoresistive accelerometer measures acceleration by detecting changes in the resistance of a piezoresistive element due to mechanical stress. Capacitive accelerometers measure acceleration by detecting changes in capacitance due to relative displacement of a microstructure caused by acceleration. Surface acoustic wave accelerometers rely on acoustic waves traveling along the surface of a substrate. Acceleration causes a phase shift in the wave, which can be detected and / or measured to determine the acceleration. Fiber optic accelerometers utilize fiber optic cables to detect strain caused by acceleration. Changes in the optical signal traveling through the fiber can be measured to determine the acceleration. Differential capacitive accelerometers use two sets of capacitor plates that move differentially with acceleration. The resulting differential capacitance change can be converted into an acceleration reading. In tunneling accelerometers, the movement of a detection mass causes a change in the tunneling current between two electrodes. This current change can be used to calculate the applied acceleration. Thermal accelerometers utilize the heating of a resistive element due to convection caused by acceleration. The change in resistance is proportional to the applied acceleration. Microfluidic accelerometers use fluid dynamics principles to detect acceleration. The motion of a fluid column within a microfluidic channel changes with acceleration, enabling accurate measurements.

[0015] Accelerometer sensors can be mounted to a tire, for example, to one or more of the following: the tire tread (e.g., inside the tread grooves and / or encapsulated by one or more tread elements), sidewall, bead, liner, belt or cord, bead wires, filler rubber, and / or tread clips. In a preferred embodiment, the accelerometer sensor can be mounted substantially on the inner layer of the tire, such as the tire liner, in the equatorial plane. Therefore, a tire-mounted accelerometer sensor primarily senses radial acceleration a. R This radial acceleration is achieved through a R =v 2 / R s To physically connect to the speed v of the vehicle, where R s It is the radius defined by the distance between the tire's axle and the location where the accelerometer sensor is mounted (e.g., defined by the sensor's 3D geographic center).

[0016] Therefore, when the vehicle is traveling at a first speed in a first driving state, the acceleration sensor can experience a first radial acceleration and measure the first acceleration, for example, as described herein. When the vehicle is traveling at a second speed, different from the first speed, in a second driving state, the acceleration sensor can experience a second radial acceleration and measure the second acceleration, for example, as described herein, where the second acceleration is different from the first acceleration. For example, when the first speed is greater than the second speed, the first acceleration is greater than the second acceleration, and vice versa.

[0017] As described herein, an accelerometer can be configured to sense acceleration sequentially. In the sequence, T seq For example, it can be less than the predetermined maximum and / or minimum driving speed v max and / or v min T below rev / 2, allowing for two subsequent acceleration measurements within a single tire rotation. This ensures that the acceleration sensor is excluded if it is within the contact imprint at time t0, leaves the contact imprint area, or is outside the contact imprint region at time t0+T. seq Return to the scene where the contact imprint was made.

[0018] Tire rotation time T rev =2πR t / v is limited, where R t is the tire radius between the tire's axis and the tread surface that will contact the road, and v is the speed of the vehicle.

[0019] Contact Imprint Time T cp (For this, a point on the tire's circumference lies within the tire's contact patch.) This can be determined by the vehicle's speed v and the tire's radius R. t and the part p of the tire circumference cp(Typically, for example, 1% to 10% or about 5%), this portion is defined as being in contact with the ground, thus forming a contact imprint: T cp =p cp ·T rev =p cp 2πR t / v.

[0020] Minimum speed v min This could involve speeds higher than typical parking speeds, such as 5 km / h, 10 km / h, or 15 km / h. The predetermined maximum driving speed v max This could, for example, refer to the typical maximum speed at which a particular vehicle can travel, such as, for a truck, approximately 90 km / h or 100 km / h.

[0021] In one example, the method may also include a time interval T. rep Repeated measurement sequences.

[0022] This offers the following advantages: updated acceleration values ​​can be provided periodically, and tire mileage can be determined based on these updated acceleration values. The higher the measurement frequency and T... rep The shorter the step size, the smaller the step size for measuring / sampling acceleration. Once T... rep If the acceleration is on the same order of magnitude as the change in vehicle speed, then the acceleration is sampled in a quasi-continuous manner, and T is further reduced. rep This will no longer result in any significant increase in the accuracy of tire mileage determination.

[0023] Based on the above, T can be selected as follows. rep :T rep For example, the time may be in the range of 1 to 60 seconds, preferably 5 to 30 seconds, and more preferably 10 to 20 seconds.

[0024] The results show that within the aforementioned approximately 15-second range, T... rep A favorable balance is achieved in such a way that, on the one hand, it produces a sufficiently high sampling rate to provide accurate tire mileage determination; and on the other hand, it is so low that the method can be performed in an economical manner, saving energy in the intervals between sequences of up to 60 seconds, while acceleration measurements can take, for example, less than a second.

[0025] The method may also include, for example, discarding at least one acceleration measured in two or more acceleration measurements of the measurement sequence at least once per measurement sequence.

[0026] This can advantageously lead to the discarding of all acceleration values ​​measured when the accelerometer is within the contact imprint.

[0027] The discarding can be accomplished, at least in part, based on, for example, evaluating the magnitude of the measured acceleration values ​​by comparing the magnitudes of acceleration values ​​in a sequence:

[0028] For example, discarding may include discarding the lowest acceleration measured in the measurement sequence.

[0029] Therefore, because lower acceleration is expected when the accelerometer is within the contact imprint, the method can automatically identify and discard erroneous acceleration values, determining tire mileage only based on erroneous acceleration values. This improves the reliability and accuracy of the method and the determined tire mileage.

[0030] In some examples, the measurement sequence may include three or more acceleration measurements; the method also includes determining the average acceleration value for each measurement sequence based on at least two acceleration values ​​that were not discarded.

[0031] In this article, v max For example, the speed range can be from 60 km / h to 140 km / h, preferably from 80 km / h to 100 km / h.

[0032] These ranges could be, for example, the actual maximum speed of heavy-duty vehicles like trucks, for which this tire mileage determination can be particularly relevant. Specifically, v max Choosing a speed limit equal to or higher than the corresponding vehicle speed limit can be advantageous: for example, in Europe, typical speed limits are 80 km / h to 90 km / h for trucks and 120 km / h to 130 km / h for cars. In some US states, for example, the speed limit is 85 mph (137 km / h) for both trucks and cars. This allows ensuring that, under expected conditions, the driver operating the vehicle does not exceed or rarely exceeds the stated speed limit. max .

[0033] In this article, v min It can be within the range of 5km / h to 30km / h, preferably within the range of 10km / h to 20km / h.

[0034] These ranges include rates low enough that it cannot be guaranteed that non-erroneous acceleration measurements outside the contact imprint do not significantly contribute to the overall accuracy and reliability of the method.

[0035] In this article, T cp It can be 0.01·T rev up to 0.15·T rev Preferably 0.025·T rev up to 0.075·T rev Within the range.

[0036] We assume that these values ​​are accurate enough to model the true contact marks of the tire, and thus improve the accuracy and reliability of the method.

[0037] T cp Adjustments can be made, for example, at least in part, based on the tire's inflation status, for example, by tire pressure and / or temperature measurements (e.g., by temperature and / or pressure sensors mounted to the tire in a manner similar to or the same as acceleration sensors).

[0038] The method may also include, for example, determining tire mileage by a calculation component based on acceleration measurements, wherein determining tire mileage may be performed at least once, for example, at each time interval associated with the measurement sequence.

[0039] This could, for example, lead to an efficient and energy-saving way to progressively determine tire mileage, thereby achieving satisfactory efficiency, accuracy, and reliability of the method.

[0040] A second aspect of the invention relates to a method for determining tire mileage for a tire. The method includes measuring the tire's radial acceleration in one or more acceleration measurements by an acceleration sensor mounted to the tire, and calculating a reference acceleration for a reference speed by a calculation unit. The reference speed includes speeds from a predetermined list of speeds, and the calculation includes obtaining the reference acceleration by discrete integration over an initial value for each reference speed. The method also includes determining a tire speed based at least in part on the measured acceleration and the reference acceleration.

[0041] The acceleration is measured by an acceleration sensor installed on the tire, as described herein.

[0042] Regarding the second aspect, the inventors understand that calculating reference acceleration for a reference speed can yield various advantages. Specifically, discretization of the method related to the fact that the reference speed includes speeds from a predetermined speed list allows for a reduction in the amount of computation required, computational complexity, and / or storage required, enabling the method to be performed, for example, in an extremely efficient and energy- and cost-effective manner. Therefore, the method can even be performed by a tire-mounted computing component, allowing the tire to directly output its mileage to, for example, an external device such as a remote server and / or a device mounted on the vehicle.

[0043] The odometer readings are based on measurements of the mean radial (centrifugal) acceleration. The mean radial acceleration is converted to the vehicle speed using a convenient (in a more nuanced sense, as explained below) standard wheel radius R0: v0 2 =aR0, where v0 is the speed of a standard vehicle with a wheel of radius R0.

[0044] If the actual wheel radius is Rt Then the true wheel speed v (i.e., the speed of the vehicle) can be obtained through v 2 =v0 2 R t / R0 is used to represent it.

[0045] Then, the distance x traveled by the wheel can be approximated as...

[0046]

[0047] if If it is a constant (measurements occur at regular intervals), then:

[0048]

[0049] This means that, given the above considerations, in order to assess the distance x traveled by the wheel, the only calculation required for each acceleration measurement is the calculation of the corresponding speed v. 0i Summation. By multiplying the rates by a constant. The final distance traveled x can be evaluated, for example, just before the distance traveled x is sent by a server (e.g., a remote and / or cloud-based server) (e.g., after the accumulated rate has been sent) and / or by a tire-mounted component (e.g., a computing component operatively connected to an acceleration sensor as described herein).

[0050] The inventors recognize that this framework can be used to significantly simplify mileage determination, making it more economical, faster, easier, more reliable, and / or performable by smaller and / or cheaper components / computing units (e.g., tire-mounted computing units). This optimization is based on calculating a reference acceleration against a reference speed and determining the tire speed, at least in part, based on the measured acceleration and the reference acceleration, as described herein.

[0051] In detail, a good approximation of speed can be achieved by simultaneously adhering to the following requirements of the method, which allow for the advantages mentioned in this paper: a well-defined resolution (achieved at 1 km / h in the test implementation), operation using only integers, minimizing the number of complex operations (such as multiplication, division, or even more complex operations), and optimizing memory consumption by avoiding the use of lookup tables and keeping the code / computer used to execute the method described in this paper within a very low footprint. Within this framework, calculating the reference acceleration against the reference speed and determining the tire speed based at least in part on the measured acceleration and the reference acceleration can be performed as follows:

[0052] The calculation of reference acceleration based on reference velocity can be based on the following understanding: The inventors discovered that v0 2 =aR0 is restated as

[0053]

[0054] in It is transformed through the constant λ The acceleration of the sampling, at the same time The speed is expressed in km / h. Multiply by a constant. And by dividing by λ, the inventors obtained:

[0055]

[0056] Then, through the By taking the second derivative, the inventor obtained the acceleration used for sampling. The second derivative of is expressed as follows:

[0057]

[0058] The method may include an (initial) calibration step, wherein, for example, calibration may include: selecting a constant. To make it as close as possible to the true value R t ;choose (Because it can represent unit conversions, it can be a real number, for example, in the inventor's first test.) ) and constants ,so that

[0059]

[0060] As a result, the calibration may therefore include measuring the vehicle speed and correlating that vehicle speed with acceleration measured by an acceleration sensor as described herein, such that the vehicle speed can be determined at least in part based on the radial acceleration measured by the acceleration sensor, with, for example, a reduced error relative to the contact imprint described herein. In some examples, the calibration is performed only once for a tire and / or for a set of tires comprising multiple tires (e.g., tires with the same and / or similar R... t For tires, performing the calibration only once may be sufficient.

[0061] After choosing the constant, as described herein and at least under good approximation, the inventors found that the evaluable parameter... This parameter is related to a specific rate. The centrifugal acceleration is proportional to the speed, with a resolution of approximately 1 km / h.

[0062] In essence, for each reference speed, the initial value (e.g., Performing discrete integration and using integer reference velocities and reference accelerations significantly reduces the required computational cost and storage. This makes the entire method so efficient that it can be performed, for example, by a tire-mounted computational component (e.g., a computational component included in a sensor unit comprising an acceleration sensor and a computational component, and / or a computational component where the computational component is included in an acceleration sensor).

[0063] Tire speed is determined at least in part based on the measured acceleration and the reference acceleration.

[0064] Determining tire speed may involve comparing the measured acceleration with a reference acceleration.

[0065] This can, for example, produce the following advantages: the reference acceleration can be determined in a way that saves energy, (computational) costs and / or storage, for example, as described herein.

[0066] For example, the calculation may include calculating the reference acceleration by means of a discrete integral, wherein the discrete integral may be an integral of velocity that has been shown to be particularly well suited to achieving the advantages cited herein.

[0067] For example, discrete integrals over speed can provide a particularly efficient and simple way to determine tire mileage, as illustrated in one example outlined in this article:

[0068] Using a simple recursive formula based on the discrete integral of D (corresponding to the second derivative of acceleration with respect to velocity), the inventors obtained:

[0069]

[0070] Where d n This corresponds to the first derivative of acceleration with respect to velocity at n km / h, and d n-1 This corresponds to the first derivative of acceleration with respect to velocity at n-1 km / h. The factor "1" relates to the fact that, in the example above, the method samples in steps of 1 km / h. Other step sizes are also possible, such as smaller (e.g., 0.1 km / h or 0.5 km / h, optionally when switching to other units (e.g., m / h) to maintain integer velocity values) or larger (e.g., 2 km / h, 5 km / h, or 10 km / h). Based on this, the inventors discovered that d can be calculated solely based on integers and their addition. n An exemplary approach.

[0071] Similarly, the first derivative can then be used to determine acceleration based on this:

[0072]

[0073] in and This could be, for example, a starting point constant appropriately defined in the calibration step. Similarly, the factor "1" relates to the fact that, in the example above, the method samples in steps of 1 km / h. Other step sizes, such as smaller (e.g., 0.1 km / h or 0.5 km / h) or larger (e.g., 2 km / h, 5 km / h, or 10 km / h), are also possible. At each rate step n, It can be estimated and / or compared with The current measurement is compared. When the condition is met... At that time, a rate with the required resolution had been found. .

[0074] Two equations and They can be linked together, for example, in a loop as described herein, such that a reference acceleration is determined for at least one reference velocity.

[0075] The basic idea involves finding some constants to achieve the desired rate resolution, and then using simple calculations to evaluate the correct rate. Specifically, the method only requires a summation, which will be compared with... (It only requires one integer multiplication) for comparison.

[0076] In the current specific implementation targeting mileage for truck tires, a good choice of constant has been found to be... and This gives , , The value of .

[0077] A viable alternative is to evaluate Among them, such as those previously selected and satisfy Then, evaluate its optimized integer square root. This may be sufficient, and for some rates (higher rates), it is comparable to [previous rate] in terms of computational steps (and time). and Recursive computation is even more efficient than traditional methods, but at the cost of including other operations (at least left and right shifts) in the computation and significantly increasing the code size. Therefore, this becomes a problem of finding the optimal solution for the computational requirements of the specific system.

[0078] Integrals of speed can be performed at equal speed intervals. In the example above, the equal speed interval is, for example, 1 km / h, but it could also be, for example, 0.1 km / h, 0.5 km / h, 2 km / h, 3 km / h, 4 km / h, 5 km / h, or 10 km / h, or any other interval. This can result in the advantage of a simplified method, and on the one hand, it can produce suitable sampling intervals, and on the other hand, it allows for simplification of the steps of the method as outlined herein.

[0079] The inventors have shown that speed intervals in the range of 0.1 km / h to 10 km / h, preferably 0.5 km / h to 2 km / h, are particularly advantageous for achieving high accuracy in tire mileage determination.

[0080] The method may include discrete integrals, which may include recursive summations, and / or the reference velocity and / or reference acceleration may be integers. For example, in the example described herein, this may involve two equations. and .

[0081] In this example, the recursive summation includes a first step and a second step; wherein the first step includes calculating the first derivative of the reference acceleration; and the second step includes calculating the reference acceleration based at least in part on the first derivative of the reference acceleration.

[0082] Recursive summation can include integer initial values, such as those described in this paper. In the example of truck tires described in this paper, a good choice of constant is found to be... and This gives , , The values ​​are integers, and these values ​​are the initial values.

[0083] In some examples, the method may also include T rep At least one step in the method of repeating time intervals.

[0084] Therefore, at least one step in the method can be performed every time interval T. rep Performed once. Generally, this enables continuous tire mileage determination, measurement of tire acceleration in the radial direction, calculation of reference acceleration against a reference speed, and / or determination of tire speed based at least in part on the measured acceleration and reference acceleration. In a preferred embodiment, T... rep Repeat the steps a sufficient number of times at time intervals to achieve repeatable / quasi-continuous tire mileage determination.

[0085] In some examples, the method may also include determining tire mileage based on one or more acceleration measurements using a computing device, wherein the tire mileage is determined at intervals (e.g., T) associated with the one or more acceleration measurements. rep ) Execute at least once.

[0086] Generally speaking, the steps of the methods referred to herein as the first and second aspects of the invention, as well as their optional steps and / or features, can be combined with each other. For example, the aspect of how to measure acceleration according to the first aspect of the invention can be implemented in the second aspect of the invention.

[0087] Therefore, the following optional features relate to both the first and second aspects of the invention:

[0088] In some examples, determining tire mileage may include determining tire speed based at least in part on measured acceleration; and multiplying the tire speed by the duration of the time interval associated with the measurement sequence, preferably T. rep .

[0089] This method of discretely approximating tire mileage can constitute a simple and efficient approach.

[0090] The method may also include, for example, providing tire mileage to an external server, preferably a cloud-based server.

[0091] This can, for example, enable centralized data collection and / or processing, which may open up new possibilities for outsourcing functionality to the server. For instance, when tire mileage is provided, the server can be configured to determine the tire's wear condition and / or wear rate based on that mileage, for example, by further considering other tire parameters such as pressure, temperature, forces acting on the tire, and / or tread profile parameters. Any aspect described herein with reference to a remote server can also be implemented using tire-mounted computational components, and vice versa.

[0092] The method may also include identifying the tire by a transponder, preferably an RFID tag; and / or associating the tire with an acceleration sensor.

[0093] This identification and / or association is particularly advantageous because it allows for the automatic tagging of data provided by the methods described herein, which facilitate data management and / or further data processing, storage, etc.

[0094] For example, tire identification can be based at least in part on tire information (e.g., SGTIN-96). This can also be written, for example, based on QR codes and / or barcodes on the tire. Regardless of how the tire is identified, it is necessary to read this information in some way and pair it with the acceleration sensor.

[0095] The third aspect relates to a computer program that includes instructions for performing steps of the methods described herein.

[0096] The fourth aspect relates to a system comprising components configured to perform the steps of the methods described herein.

[0097] The same advantages described in the reference method in this paper apply similarly to computer programs and systems. 4. Description of the attached drawings

[0098] Figure 1a An exemplary tire is shown in a plan view in the axial direction, with the illustration highlighting the tire's contact imprint.

[0099] Figure 1b It shows Figure 1a The illustration shows three exemplary snapshots of a tire-mounted accelerometer through the tire's contact imprint.

[0100] Figure 2 An exemplary embodiment of a vehicle equipped with six tires, each of which is equipped with an acceleration sensor, is shown.

[0101] Figure 3 An exemplary three-dimensional sketch of a tire with an acceleration sensor mounted to the tire's inner liner is shown.

[0102] Figure 4 An exemplary acceleration that varies over time, as measured by an accelerometer, is shown.

[0103] Figure 5 A graph showing the determined tire mileage of the truck's six tires over time is presented, where the tire mileage is determined according to the method described herein. 5. Detailed Implementation

[0104] Figure 1a A plan view in the axial direction shows a wheel 20 with a tire radius R. t An exemplary tire 10 with a tire-mounted acceleration sensor 30 is shown in the illustration, where the contact imprint CP of the tire 10 is highlighted. Figure 1a Tire 10 is shown rotating counterclockwise, which translates to the vehicle moving to the left, as... Figure 1a As indicated by the arrow in the image. Figure 1a The illustration shows an enlarged portion of tire 10 in contact with the ground. The portion of tire 10 in contact with the ground is referred to as the contact imprint CP and has a length L in the circumferential direction of the tire. CP This length corresponds to approximately 5% of the circumference of tire 10.

[0105] For illustrative purposes, the following is shown Figure 1a The acceleration sensor 30 is mounted inside the tire 10 and is not visible from the outside in most preferred embodiments. However, there are embodiments in which the acceleration sensor 30 is mounted on the outside of the tire 10 (e.g., on one of the sidewalls of the tire 10). If mounted on the sidewall, the effect of the contact imprint on the acceleration signal may be less visible; the effect becomes almost negligible when close to the rim. However, at the same time, the amount of acceleration measured by the sensor may decrease simultaneously. In this document, the acceleration sensor 30 is typically part of a tire-mounted sensor (unit), which may also include, for example, computing components and / or transponders, as described herein.

[0106] The size and / or shape of the contact imprint CP may depend, for example, on tire load, pressure, temperature, the number of tires mounted on the vehicle, the weight distribution on the vehicle and / or tire material / composition, and / or may be the same or different for different tires of the same vehicle.

[0107] The inventors recognized that it is crucial to consider the influence of contact imprint (CP) in methods used for tire mileage determination. This influence is achieved through… Figure 1b Example:

[0108] Figure 1b It shows Figure 1a The illustration shows three exemplary snapshots of a tire-mounted accelerometer 30 passing through the contact patch of the tire 10 due to the counterclockwise rotation of the tire 10: In the first snapshot (see top), the accelerometer 30 is located to the left of the contact patch CP, and thus can perform undisturbed acceleration measurements. In the second snapshot (see middle), the accelerometer 30 is further rotated counterclockwise. Therefore, the accelerometer is located at a length L of the contact patch CP. CP Inside, and because the accelerometer is located at a distance from the axis less than from... Figure 1a R t The radius of the contact imprint CP may be affected, potentially causing interference in the acceleration measurement of the accelerometer. This effect becomes more pronounced for tires supporting vehicles with increased loads, as the CP length becomes longer in such scenarios. In the third snapshot (see bottom), the accelerometer 30 is further rotated counterclockwise. Therefore, the accelerometer is positioned to the right of the contact imprint CP, and thus can perform undisturbed acceleration measurements.

[0109] exist Figure 1bIn the example, the first and third acceleration measurements can therefore be suitable for consideration for tire mileage determination, while the second acceleration measurement (where the acceleration sensor 30 is located within the contact imprint CP) can be discarded.

[0110] Figure 2 The top portion of the diagram shows the vehicle (i.e., the one equipped with six tires 10a, 10b, 10c, 10d, 10e, 10f). Figure 2 The example trailer (grey) shown in the example, with each of the six tires equipped with an acceleration sensor 30a, 30b, 30c, 30d, 30e, 30f, is an exemplary configuration. Figure 2 The bottom portion of the diagram shows a side view of an exemplary trailer for reference. More specifically, in other examples, the vehicle could be, for example, a truck, a car, etc. Thus, Figure 2 This illustrates that the concept of the invention is applicable to various types of vehicles (e.g., vehicles with and without motors). Figure 2 An exemplary trailer includes a left front tire 10a with acceleration sensor 30a, a right front tire 10b with acceleration sensor 30b, and four rear tires 10c, 10d, 10e, and 10f, namely, a left inner rear tire 10c with acceleration sensor 30c, a right inner rear tire 10d with acceleration sensor 30d, a left outer rear tire 10e with acceleration sensor 30e, and a right outer rear tire 10f with acceleration sensor 30f. One or more of the acceleration sensors 30a, 30b, 30c, 30d, 30e, and 30f may be configured to provide at least some of the data described herein, such as tire mileage and / or (measured and / or referenced) acceleration, to a vehicle-based computing unit / server 40 and / or a remote server 50. This concept is generally applicable to other vehicles (e.g., including another number of tires and / or tires with different arrangements).

[0111] Figure 3 An exemplary three-dimensional sketch of a tire 10 with an acceleration sensor 30 mounted to the inner liner of the tire 10 is shown.

[0112] Figure 4 An exemplary acceleration 400 as measured over time by an acceleration sensor is shown.

[0113] Specifically, for those time periods 410a and 410b during which the sensor is outside the contact imprint, the measured acceleration fluctuates around a specific level between -50g and -75g. During these time periods, the acceleration sensor can perform accurate acceleration measurements, which provide representative acceleration values ​​to determine tire mileage based on these values.

[0114] After time periods 410a and 410b, the accelerometer approaches the contact patch. The circumferential curvature of the tire is highest at the two circumferential ends of the contact patch. Therefore, the highest radial acceleration acts on the accelerometer as it passes these two end portions of the contact patch. As a result, the accelerometer records the highest absolute acceleration values ​​(in...) when it enters the contact patch 420a and 420b and when it leaves the contact patch 440a and 440b. Figure 4 The example shows an acceleration of almost -125g.

[0115] When the sensor is within the contact patch, it experiences no radial acceleration because the curvature of the tire's circumference is essentially zero (assuming a flat surface over which the vehicle is traveling). On a real truck / car tire, the acceleration at the center of the contact patch is therefore typically (close to) zero because that portion of the tread and / or liner is stationary. Therefore, the measured acceleration drops to zero at times 430a, 430b.

[0116] In short, Figure 4 This illustrates why it is so important to measure acceleration from time to time when the accelerometer is not located within the contact imprint in order to achieve accurate and reliable mileage determination based on acceleration measurements.

[0117] Figure 5 A graph showing the determined tire mileage of the truck's six tires over time is presented, where the tire mileage was determined according to the method described herein. It is noteworthy that nearly identical mileage was measured for all wheels, and the final error is quite low (i.e., 5% or less). The total relative mileage difference between the six tires is approximately 1%. Specifically, they differ by about 1,000 km over a total driving distance of approximately 96,000 km.

[0118] Exemplary code that allows tire mileage determination when provided with acceleration measurement input can implement the steps of the method of the present invention as follows:

[0119] In the initial calibration step, , and It can be set to a suitable value as described in this article. Additionally, the step size for subsequent discrete integration can also be set. For example, the following integers can be selected: , , and

[0120] Once these values ​​are set, the equation Can be used to provide recursively and The value of . Specifically, using the example starting values ​​described above, this can produce: , , , Etc. In the example code, the equation This can be implemented, for example, in a loop (e.g., a for loop) until an interval condition is met. The interval condition may, for example, correspond to changing the reference acceleration... Multiply by the acceleration measured by the acceleration sensor mounted on the tire The comparison can be performed, for example, within each complete iteration of the for loop. Essentially, the exemplary code therefore includes... = 1 km / h reference speed step (from 2 km / h and above) Counting upwards in increments of 1 km / h, the reference acceleration is calculated for the reference speed until the intermittent condition is met. Thus, in each cycle, the reference acceleration is calculated for a specific speed, where the speed increases with each cycle. .

[0121] When the intermittent condition is met, a reference acceleration can be assumed. The measured acceleration matches the accuracy of the code, and a reference speed associated with the reference acceleration can be assumed to be the vehicle speed, and tire mileage can be determined based on that vehicle speed. Because the reference acceleration increases with each cycle, when the reference acceleration is equal to or greater than the measured acceleration multiplied by [a certain value], [the system will determine the tire mileage]. At this time, the intermittent criterion can be met. Therefore, two speed values ​​can be used to determine tire mileage: a speed at which its reference acceleration is equal to or greater than the measured acceleration; or a speed from a cycle that occurs exactly before the intermittent condition is met, which essentially corresponds to the highest reference acceleration less than the measured acceleration. In the example of the exemplary code described herein, either of these two speed values ​​can be determined by multiplying the speed value by the time interval associated with the measurement (e.g., the time interval T between two consecutive acceleration measurement sequences as described herein). rep ) were selected for tire mileage calculation.

Claims

1. A method for determining tire mileage, the method comprising: Acceleration along the radial direction of the tire is measured in one or more acceleration measurements using an acceleration sensor mounted to the tire. The calculation unit calculates the reference acceleration relative to the reference velocity; The reference speed mentioned therein includes speeds from a predetermined speed list; and The calculations described therein include obtaining the reference acceleration by discretely integrating the initial value with respect to each reference velocity; as well as The tire speed is determined at least in part based on the measured acceleration and the reference acceleration.

2. The method of claim 1, wherein determining the tire speed comprises comparing the measured acceleration with the reference acceleration.

3. The method according to claim 1 or 2, wherein the discrete integral is an integral of the velocity.

4. The method according to any one of claims 1 to 3, wherein the integration of the velocity is performed at equal velocity intervals.

5. The method according to claim 4, wherein the speed interval is in the range of 0.1 km / h to 10 km / h, preferably 0.5 km / h to 2 km / h.

6. The method according to any one of claims 1 to 5, wherein the discrete integral comprises recursive summation, and / or wherein the reference velocity and the reference acceleration are integers.

7. The method according to claim 6, wherein the recursive summation includes a first step and a second step; The first step includes calculating the first derivative of the reference acceleration; and The second step includes calculating the reference acceleration based at least in part on the first derivative of the reference acceleration.

8. The method of claim 6 or 7, wherein the recursive summation includes an integer starting value.

9. The method according to any one of claims 1 to 8, the method further comprising using T rep At least one step of the method is repeated at time intervals.

10. The method of any one of claims 1 to 9, further comprising determining tire mileage by a calculation component based on the one or more acceleration measurements, wherein determining the tire mileage is performed at least once per time interval associated with the one or more acceleration measurements.

11. The method of claim 10, wherein determining the tire mileage comprises determining the tire speed based on the acceleration measurement; and multiplying the tire speed by a duration of the time interval associated with the one or more acceleration measurements, the duration preferably being T. rep .

12. The method according to any one of claims 1 to 10, the method further comprising providing the tire mileage to an external server, preferably a cloud-based server.

13. The method according to any one of claims 1 to 12, further comprising identifying the tire by means of a transponder, preferably an RFID tag; and / or associating the tire with the acceleration sensor.

14. A computer program comprising instructions for performing the steps of the method according to any one of claims 1 to 13.

15. A system comprising components configured to perform the steps of the method according to any one of claims 1 to 13.

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