Systems and methods for direct and indirect tire pressure monitoring and calibration

Abstract

A tire monitoring system including a direct tire monitoring system including a sensor for directly sensing an internal tire pressure on at least one (1) of N tires on a vehicle, at least one indirect tire monitoring system for sensing a physical attribute of at least one (1) of N tires on a vehicle, and a processor capable of executing program instructions for a calculation of tire pressure that uses the output of the at least one indirect tire monitoring system to compute a tire pressure for the at least one (1) of N tires based upon the sensed physical attribute; and uses the output of the direct tire monitoring system that directly sensed an internal tire pressure to calibrate the computed tire pressure.

Description

PCT APPLICATION FOR LETTERS PATENTFORSYSTEMS AND METHODS FOR DIRECT AND INDIRECT TIRE PRESSURE MONITORING AND CALIBRATIONBYBENEDICTO DELOS SANTOS;COLTON A. OTTLEY;JARED K. JONAS;UTKARSH GUPTA;DON SAXBY;JUMA BELKNAP;NICK RUDH;STACY J. MORRIS BAMBERG;NATHAN BRIGGS;ANDCOLIN EICHINGERCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application, under 35 U.S.C. § 119, claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 569,432 filed on March 25, 2024, and entitled “SYSTEMS AND METHODS FOR DIRECT AND INDIRECT TIRE PRESSURE MONITORING AND CALIBRATION,” the contents of which is hereby incorporated by reference herein.FIELD OF THE DISCLOSURE

[0002] This disclosure relates generally to vehicle Tire Monitoring Systems (TMS). More particularly, this disclosure relates to systems and methods for implementing and calibrating combined systems for direct TMS (d-TMS) and indirect TMS (i-TMS).BACKGROUND

[0003] TMS and Tire Pressure Monitoring Systems (TPMS) are useful for maintaining optimal tire pressure, enhancing safety, and improving fuel efficiency in vehicles. These systems measure tire pressure and, optionally, tire temperature and use this information to guide the vehicle operator of this information.

[0004] TMS is part of a newer generation of tire sensors that output not only tire pressure but also other relevant information like tire load, tread depth, tire ID, road surface condition, tire temperature, and much more. These systems comprise various combinations of sensors like pressure sensors, accelerometers, strain gauges, etc., which work in conjunction to extract the information mentioned above.

[0005] There are two main types of TPMS pressure sensing: direct, which uses a physical pressure sensor, and indirect, which does not use a physical pressure sensor and relies on alternate sensors, like the wheel speed encoders, and correlates their readings to the pressure levels inside the tires. Each has its own set of advantages and disadvantages.

[0006] For example, direct TPMS (d-TPMS) has the advantage of providing accurate real-time tire pressure data for each tire in which it is installed. Additionally, d- TPMS can be configured to alert the driver immediately if there is a significant change in tire pressure, ensuring swift action can be taken. Some d-TPMS embodiments also provide tire temperature readings, which can be useful for tire maintenance.

[0007] Exemplary disadvantages of d-TPMS are that the sensors can be expensive to replace. This is especially true if sensors are damaged during tire servicing. Relatedly, d- TPMS sensors have batteries that eventually run out and need replacing. Additionally, aftermarket tires and wheels may not always be compatible with the vehicle’s original equipment manufacturer (OEM) d-TPMS configuration.

[0008] Examples of indirect TPMS (i-TPMS) advantages include that i-TPMS is generally cheaper to maintain because it does not use physical pressure sensors in each tire. Relatedly, without the need to replace in-tire sensors and batteries, maintenance costs are typically lower. Also, i-TPMS is usually more adaptable to different types of aftermarket tires and wheels.

[0009] Examples of i-TPMS disadvantages include i-TPMS does not provide pressure readings for individual tires; it only alerts when there is a variance in rotation speed, suggestive of pressure loss. Without proper calibration, i-TPMS might fail to detect gradual pressure loss or differences in pressure among tires that are still within an acceptable rotation speed range. Likewise, i-TPMS provides less accurate tire pressure readings since it typically uses the vehicle’s anti-lock braking system (ABS) sensors to approximate pressure and if the calibration is not performed correctly, the i-TPMS may provide inaccurate readings. This can happen if the tires are not inflated to the proper pressure before recalibration or if the calibration process is not followed per the manufacturer’s instructions. Also, i-TPMS may not alert as quickly to sudden tire pressure changes because it relies on wheel speed data, and i-TPMS can be influenced by factors other than tire pressure, such as uneven tire wear or different tire sizes, leading to false alerts or failure to alert when necessary. Further, i-TPMS typically needs recalibration after tire rotation, tire pressure adjustments, or tire replacement, which can be inconvenient. These calibrations typically require manual intervention by the tire shop technicians or the driver. Apart from the inconvenience, such calibration needs may also increase downtime, which is significant, especially in the trucking industry. The accuracy of such i-TPMS also relies heavily on the effectiveness of these calibration requirements.

[0010] As discussed above, calibration is typically a significant weakness of an i- TPMS which use the vehicle’s ABS sensors to monitor tire rotations and infer tire pressure levels and whether a tire is underinflated or overinflated. However, when a tire’s pressure is low, it has a smaller effective diameter and rotates faster than the tires with the correct pressure and can give false readings of pressure. Similarly, overinflated tires can give spurious i-TPMS readings as discussed in more detail below.

[0011] Generally, i-TPMS calibration is performed by inflating all tires to the manufacturer’s recommended pressure before calibration to ensure a proper baseline. Then, most vehicles with i-TPMS have a specific procedure to enter a calibration mode. This often involves navigating through the vehicle’s onboard computer or infotainment system. In some vehicles, it might be as simple as pressing and holding a calibration button on the dashboard. After initiating the calibration mode, one typically needs to drive the vehicle for a certain distance or time period at a specified range of speeds. This allows the i-TPMS to learn the rotational characteristics of each tire at the correct pressure. The exact requirements can vary by vehicle manufacturer. After driving the required distance or time, the i-TPMS system sets the recorded readings as the baseline for correctly inflated tires. From this point, the i-TPMS continuously monitors the rotational speed of the tires. If a tire starts rotating faster than this baseline, the system interprets it as underinflated (conversely, slower rotation indicates overinflated) and triggers a warning light or message to the driver. As will be apparent to those of ordinary skill having the benefit of this disclosure, it is often recommended to recalibrate an i-TPMS after any tire maintenance, such as changing, rotating, or replacing tires or after adjusting tire pressure.

[0012] In summary, d-TPMS offers more precise and immediate rapid tire pressure information measurement, along with detection of slow leaks or punctures (or blowouts) but comes at a higher cost and maintenance requirements. On the other hand, i-TPMS is more economical and requires less maintenance, but it is less accurate or sensitive to small changes and might not alert as quickly to pressure changes or identify slow leaks. The choice between the two depends on the priorities of the vehicle owner, whether they favor accuracy and immediacy or cost-effectiveness and ease of maintenance. Other drawbacks, issues, inconveniences, and disadvantages also exist.SUMMARY

[0013] Accordingly, disclosed embodiments address the above, and other drawbacks, issues, inconveniences, and disadvantages of existing systems. Other advantages and efficiencies of disclosed systems and methods also exist.

[0014] As used herein, “flexible,” “extensible,” “compliant,” “deformable,” and the like are used somewhat interchangeably and all mean that some amount of flexing, stretching, compression, twisting, bending, or the like, exists for the described embodiment. As used herein, “extensible” is generally used to collectively mean all of the above.

[0015] As used herein, the terms “top,” “bottom,” “left,” “right,” “vertical,” “lateral,” “upper,” and “lower” can refer to relative directions or positions of features shown in the Figures. For example, “upper” or “uppermost” can refer to a feature positioned closer to the top of a page than another feature. These terms, however, should be construed broadly to include devices and assemblies having other orientations, such as inverted or inclined orientations where top / bottom, over / under, above / below, up / down, and left / right can be interchanged depending on the orientation.

[0016] As used herein for disclosed embodiments, “TMS” refers collectively and alternatively for either TMS or TPMS and involves systems that not only measure tire pressure but also other dynamic properties like temperature, tire load, tread depth, etc., as described above. The direct and indirect terminology has also been carried forth for the disclosed TMS sensors (i.e., d-TMS ori-TMS depending on direct or indirect measurement, respectively). Embodiments of disclosed TMS may be comprised of accelerometers, strain gauges, extensible sensors, etc., that are used to record the tire’s responses while it’s in motion or stationary as detailed below.

[0017] Disclosed embodiments include at least one direct TMS (d-TMS) having a contact patch sensor (CP) and / or a sidewall sensor (SW). Exemplary embodiments of CP and SW sensors are disclosed in PCT / US2024 / 012043, filed January 18, 2024, titled “Systems And Methods For In-Tire Wheel Force Transducer” which is incorporated in its entirety by reference herein. The d-TMS includes a physical pressure sensor, typically a pressure Micro-Electro-Mechanical System (MEMS). Embodiments also include an indirect TMS (i-TMS) comprising a contact patch sensor (CP) and / or a sidewall sensor (SW). The i-TMS does not include a physical pressure sensor and the CP and SW sensors in the i-TMS component can be accelerometers, strain gauges, extensible sensors, etc., as described above.

[0018] Embodiments also include at least one processor device capable of executing program instructions for an algorithm that uses the outputs (or assessed signal characteristics) of the CP and / or SW sensors, among other vehicle-related parameters, to compute tire pressure (TP) and that uses the TP measured by the d-TMS to calibrate and thereby enhance the pressure estimated by the i-TMS sensors.

[0019] Disclosed embodiments remedy the weaknesses of the existing i-TPMS enumerated above and reduce the cost of deploying TMS to vehicles. Further and among other things, disclosed embodiments allow individual tire pressure data to be collected, allow detection of slow leaks in all tires of a vehicle, improve accuracy by utilizing signalsfrom tires instead of the wheels, thereby making it more sensitive to tire pressure and, thus, inherently more accurate than the above noted i-TPMS approach. Additionally, combining i-TMS and d-TMS adds accuracy to the system by including a physical pressure sensor. Disclosed embodiments also reduce latency in alerts, removes the need for calibration by utilizing actual pressure readings by the d-TMS pressure MEMS in real time, removes the need for manual intervention by a shop technician or the driver, and removes sensitivity to non-pressure related factors such as uneven tire wear or different tire sizes (or tread depths), which can lead to false alerts or failure to alert when necessary. Other advantages and embodiments also exist.BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. l is a schematic illustration of d-TMS and i-TMS systems on a tractortrailer truck in accordance with disclosed embodiments.

[0021] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.DETAILED DESCRIPTION

[0022] FIG. 1 is a schematic illustration of d-TMS 102 and i-TMS 104 systems on a tractor-trailer truck 100 in accordance with disclosed embodiments. As illustrated, disclosed embodiments reduce the cost of the total TMS system by replacing most of the sensors with i-TMS systems (which do not use physical pressure sensors). For example, in the case of an 18-wheeler tractor-trailer truck 100, with the typical tire arrangement as shown in FIG. 1, the cab or tractor portion, which typically has 10 tires as shown, may have 9 (or n-1, for generalization) of the 10 (or n, for generalization) tires with i-TMS 104 systems, and with the remaining one tire as a d-TMS 102 system. The i-TMS 104 utilizes the actual pressure reading measured by the pressure MEMS inside the d-TMS 102 system in combination with the CP and / or SW measurements for estimating the tire pressure for all the tires.

[0023] Likewise, for the trailer portion of tractor-trailer truck 100, 7 (or m-1, for generalization) of the 8 (or m, for generalization) systems can be i-TMS 104, with one system a d-TMS 102. Again, the i-TMS 104 will utilize the actual pressure reading measured by the pressure MEMS inside the d-TMS 102 for tire pressure estimation.

[0024] As will be apparent to those of ordinary skill in the art having the benefit of this disclosure, the d-TMS 102 may be located in any tire of the tractor-trailer truck 100 (i.e., driver side front, passenger side rear inner or outer tire, etc., and the same for the trailer portion). Likewise, for other vehicles with more, or fewer, tires other combinations may also be used. In general, at least one d-TMS 102 and at least one i-TMS 104 system may be used.

[0025] As illustrated, the system comprises a fusion of i-TMS 104 and d-TMS 102 for all the wheels of a vehicle (e.g., truck 100). Embodiments of such a system may include a centralized hub 106 to communicate and coordinate with all the i-TMS 104 and d-TMS 102. Hub 106 may be located in any appropriate location (e.g., on tractor portion, on trailer portion, inside a dashboard, under a seat, etc.). Embodiments of hub 106 also contain the processor devices to aid in the calibration of the i-TMS 104 estimated tire pressure as disclosed herein. Embodiments of hub 106 may be a single, stand-alone device communicating to all the i-TMS 104 and d-TMS 102, or may be multiple devices distributed throughout a vehicle, or may include various wireless receivers as a relay between the tire sensor systems (104, 102) and a hub 106 communication channel. In other embodiments, hub 106 need not be included and all the computation and calibration may be done on an electronics module onboard the i-TMS 104 or d-TMS 102 system inside the tire. Exemplary electronics modules are disclosed, for example, in PCT / US2024 / 012043, filed January 18, 2024, titled “Systems And Methods For In-Tire Wheel Force Transducer” which is incorporated in its entirety by reference herein.

[0026] The TMS in each tire, whether d-TMS 102 or i-TMS 104, includes instructions for causing at least one processor device to implement algorithms that estimate tire pressure and / or relevant signal parameters from the CP and / or SW sensing elements (or sensors). Inside the d-TMS 102, there is a pressure sensor (e.g., a MEMS pressure sensor) that directly measures tire pressure. The i-TMS 104 typically does not require a pressure MEMS.

[0027] Inside the d-TMS 102, the MEMS sensor in combination with the algorithms that work on the data sensed by the CP and / or SW sensing elements (or sensors)are used to determine a correlation / calibration factor(s) that correlates the direct pressure measurement with the algorithm’s estimated pressure.

[0028] Embodiments of d-TMS 102 transmit the following data to the hub 106 or other i-TMS 104 systems that are linked together: direct tire pressure measurement, pressure calibration factor(s), and any relevant CP and / or SW sensors’ characteristics.

[0029] Embodiments of i-TMS 104 transmit the following data to the hub 106 or other d-TMS 102 system(s) that are linked together: estimated tire pressure and / or any relevant CP and / or SW sensors’ characteristics for validation or continuous learning.

[0030] Embodiments of hub 106 include processor devices and one or more algorithms applying the pressure calibration factor(s) to the estimated pressures reported by each i-TMS 104 and / or applying the pressure calibration factor(s) in combination with the relevant CP and / or SW sensors’ characteristics to a tire pressure estimation model. The corrected pressures are used in succeeding operations that require tire pressure inputs and are reported to the vehicle / driver / fleet manager. Embodiments of hub 106 may also compare the characteristics of the CP and / or SW sensors between all the i-TMS 104 and d- TMS 102 systems to output tire pressures for all the tires. In some embodiments the functionality hub 106 may also be implemented in the cloud (e.g., via wireless / cellular communication) and, therefore, does necessarily have to be a physical device onboard the vehicle.

[0031] Embodiments of both i-TMS 104 and d-TMS 102 may consist of one or more sensing elements, like the CP and / or SW, representing tire deformation in the contact patch and sidewall of a tire, respectively. Such tire deformations can be extracted through strain, accelerations (vibrations), bending, or the like. The calibrated pressures reported by disclosed embodiments may be used in various ways, for example, but not limited to, detecting under- and over- pressurized tires, detecting potentially anomalous tire conditions that can presage blowouts, detecting slow leaks, detecting defective tires (e.g., tires that are repeatedly losing tire pressure may have some defects building up to the repeated pressure loss), and the like.

[0032] As will be apparent to those of ordinary skill in the art having the benefit of this disclosure, tire pressure can be estimated via other sensing elements other than those described here. In those cases, the general principle described here, i.e., using a single direct pressure measurement to calibrate indirect estimates, can be applied. Some of these tire pressure estimation sensing elements are listed above but the list is not exhaustive and can include variations with the CP and / or SW sensing elements. Likewise, the general principleof using a direct variable measurement (e.g., pressure) to calibrate estimates of the same variable may be applied to other applications and variables (e.g., tire load, tire tread depth, tire temperature, etc.).

[0033] Among the advantages provided by disclosed embodiments are reduced hardware cost by obviating the need for pressure MEMS in each tire, improved reliability by reducing the MEMS count as extensible sensing elements used in the CP and / or SW sensors described herein are inherently more robust than pressure MEMS, and reduced power consumption in each i-TMS 104 system by the amount of energy used to power the pressure MEMS. Other advantages also exist.

[0034] Exemplary embodiments include the following:

[0035] 1. A hybrid combination of d-TMSi-TMS, both direct TMS (d-TMS using a MEMS pressure sensor in 1 of N tires) and indirect TMS (i-TMS using a combination of sensing elements (e.g. CP and / or SW sensing elements but others could be used) in all the remaining N-l tires) deployed in a single vehicle (e.g., automobile, bus, truck cab, truck trailer, etc.)

[0036] 2. A method for automatically and continually calibrating the tire pressure outputs of an indirect TMS using the actual pressure measurements of a direct TMS

[0037] 3. A method of calibrating a target variable, e.g. tire pressure, tire load, indirectly estimated by other sensed variables, e.g. contact patch differential strain or acceleration, sidewall differential strain or acceleration, by using a direct measurement of the target variable and an estimation thereof to calculate a calibration factor and applying said calibration factor to the estimates.

[0038] Other embodiments also exist.

[0039] Although various embodiments have been shown and described, the present disclosure is not so limited and will be understood to include all such modifications and variations would be apparent to one skilled in the art.

Claims

WHAT IS CLAIMED IS:

1. A tire monitoring system comprising: a direct tire monitoring system including a sensor for directly sensing an internal tire pressure on at least one (1) of N tires on a vehicle; at least one indirect tire monitoring system for sensing a physical attribute of at least one (1) of N tires on a vehicle; and a processor capable of executing program instructions for a calculation of tire pressure that uses the output of the at least one indirect tire monitoring system to compute a tire pressure for the at least one (1) of N tires based upon the sensed physical attribute; and uses the output of the direct tire monitoring system that directly sensed an internal tire pressure to calibrate the computed tire pressure.

2. The tire monitoring system of claim 1 wherein the direct tire monitoring system comprises a Micro-Electro-Mechanical System (MEMS) pressure sensor.

3. The tire monitoring system of claim 1 wherein the indirect tire monitoring system comprises a contact patch sensor.

4. The tire monitoring system of claim 3 wherein the contact patch sensor comprises at least one of an accelerometer, strain gauge, or extensible sensor.

5. The tire monitoring system of claim 1 wherein the indirect tire monitoring system comprises a sidewall sensor.

6. The tire monitoring system of claim 5 wherein the sidewall sensor comprises at least one of an accelerometer, strain gauge, or extensible sensor.

7. The tire monitoring system of claim 1 wherein the direct tire monitoring system directly senses the internal tire pressure of one (1) of N tires on the vehicle and (N- 1) indirect tire monitoring systems sense a physical attribute of the remaining (N- 1) tires on the vehicle.

8. The tire monitoring system of claim 1 further comprising a hub that communicates with the direct tire monitoring system and the at least one indirect tire monitoring system.

9. The tire monitoring system of claim 8 wherein the hub includes the processor.

10. The tire monitoring system of claim 1 wherein the processor computes a calibration factor based upon the output of the at least one indirect tire monitoring system and the output of the direct tire monitoring system.

11. The tire monitoring system of claim 10 wherein the at least one indirect tire monitoring system estimates an internal tire pressure based upon the sensed physical attribute of the at least one (1) of N tires on the vehicle and the calibration factor is used to correct the estimated internal tire pressure.

12. The tire monitoring system of claim 11 wherein the corrected estimated internal tire pressure is used by the processor in succeeding operations for continuous learning.

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