BACKUP FOR A TIRE PRESSURE MONITORING SYSTEM

Abstract

A computer includes a processor and memory, and the memory contains instructions that the processor can execute to: determine a difference between the rotational speeds of different wheels of a vehicle in response to the vehicle exceeding a vehicle speed threshold; and output a message indicating low tire pressure in one of the wheels in response to the difference exceeding a difference threshold.

Description

AREA OF TECHNOLOGY

[0001] This disclosure concerns tire pressure monitoring systems. GENERAL STATE OF THE ART

[0002] A tire pressure monitoring system (TPMS) is a system for monitoring the air pressure of a vehicle's tires. If the TPMS detects that one of the vehicle's tires is inflated below a certain threshold, a warning light illuminates on the instrument panel to inform the driver. The TPMS uses pressure sensors mounted either inside or on the outer surface of each tire. Pressure sensors mounted inside the tires communicate using short-range wireless signals. SUMMARY

[0003] This disclosure provides techniques for functional redundancy for a vehicle's tire pressure monitoring system (TPMS). In other words, the task of monitoring tire pressures can be performed even when the TPMS is inactive. When the TPMS is inactive, a vehicle computer is programmed to: determine a difference in the rotational speeds of different wheels of the vehicle in response to the vehicle exceeding a vehicle speed threshold; and issue a message indicating low pressure in one of the tires in response to the difference exceeding a difference threshold. If one tire is rotating faster than the others, it has a smaller diameter and is therefore likely underinflated. The wheel rotational speeds can be reported by wheel speed sensors on each of the wheels.Measurements from wheel speed sensors can be subject to greater fluctuations at lower speeds. Using the vehicle speed threshold can help ensure that the difference between wheel speeds is accurate enough to use for checking tire pressures.

[0004] A computer includes a processor and memory, and the memory contains instructions that the processor can execute to: determine a difference between the rotational speeds of different wheels of a vehicle in response to the vehicle exceeding a vehicle speed threshold; and output a message indicating low tire pressure in one of the wheels in response to the difference exceeding a difference threshold.

[0005] In one example, the instructions may further include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the speed threshold and the vehicle's steering angle being within a steering angle range. In another example, the steering angle range may include a straight-ahead steering angle.

[0006] In one example, the instructions may also include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and the vehicle's tire pressure monitoring system being inactive.

[0007] In one example, the vehicle may include a separate tire pressure monitoring system for each tire, and the instructions may further include instructions for determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and at least one of the tire pressure monitoring systems being inactive.

[0008] In one example, the instructions may also include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold for at least one time threshold.

[0009] In one example, the instructions may also include instructions for determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and the current operating mode of the vehicle being a first operating mode.

[0010] In one example, the difference could be between the fastest and slowest wheel speeds. In another example, the fastest and slowest wheel speeds could occur simultaneously.

[0011] In another example, the difference can be expressed as the proportion of the slowest wheel speed.

[0012] In one example, the instructions might also include instructions to set a flag in memory in response to the difference exceeding the difference threshold. In another example, the instructions might also include instructions to output the message indicating low tire pressure in response to the vehicle being started with the flag set.

[0013] In another example, the instructions may also include instructions to remove the flag in response to the fact that the difference is below the difference threshold for at least one time threshold after the flag has been set.

[0014] One method involves determining a difference between the rotational speeds of different wheels of a vehicle in response to the vehicle exceeding a vehicle speed threshold; and issuing a message indicating low tire pressure of one of the wheels in response to the difference exceeding a difference threshold.

[0015] In one example, the procedure may also involve determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and a steering angle of the vehicle being within a steering angle range.

[0016] In one example, the procedure may also involve determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and the vehicle's tire pressure monitoring system being inactive.

[0017] In one example, the vehicle may include a separate tire pressure monitoring system for each tire, and the procedure may further include determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and at least one of the tire pressure monitoring systems being inactive.

[0018] In one example, the procedure may further involve determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold for at least one time threshold.

[0019] In one example, the procedure may further involve determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and the current operating mode of the vehicle being a first operating mode.

[0020] One example would be the difference between the fastest wheel speed and the slowest wheel speed. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic top view of an example vehicle. Fig. Figure 2 is a flowchart of an example process for determining the tire pressure of a vehicle. DETAILED DESCRIPTION

[0021] Referring to the figures in which equal numbers in all of the different views denote equal parts, a computer 105 includes a processor and a memory, and instructions are stored in the memory which can be executed by the processor to: determine a difference between wheel rotations of different wheels 110 of a vehicle 100 in response to the fact that a speed at which the vehicle 100 is traveling exceeds a vehicle speed threshold; and output a message indicating low pressure of a tire 115 of one of the wheels 110 in response to the difference exceeding a difference threshold.

[0022] With reference to Fig. 1. The vehicle 100 can be any passenger car or any commercial vehicle, such as a car, truck, SUV, crossover, van, minivan, taxi, bus, etc. The vehicle 100 can include the wheels 110, the tires 115, the computer 105, a communication network 120, tire pressure monitoring systems (TPMS) 125, wheel speed sensors 130, a speedometer 135, a steering angle sensor 140, and a user interface 145.

[0023] The Computer 105 is a microprocessor-based computing device, such as a generic computing device, which includes: a processor and memory, electronic control or the like, a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), a combination of the foregoing, etc. Typically, a hardware description language, such as VHDL (Very High Speed ​​Integrated Circuit Hardware Description Language), is used in the electronic design to describe digital and mixed-signal systems, such as FPGAs and ASICs.For example, an ASIC is manufactured based on VHDL programming, which is provided prior to manufacturing, whereas logical components within an FPGA can be configured based on VHDL programming (e.g., stored in memory electrically connected to the FPGA circuit). The Computer 105 can thus include a processor, memory, and so on. The memory of the Computer 105 can include media for storing instructions executable by the processor, as well as for electronically storing data and / or databases, and / or the Computer 105 can include structures like those mentioned above, through which programming is provided. The Computer 105 can consist of multiple interconnected computers.

[0024] The computer 105 can transmit and receive data via the communication network 120. The communication network 120 can be a Controller Area Network bus (CAN bus), Ethernet, WiFi, a Local Interconnect Network (LIN), an On-Board Diagnostics (OBD-II) port, and / or any other wired or wireless communication network. The computer 105 can communicate with the TPMS 125, the wheel speed sensors 130, the speedometer 135, the steering angle sensor 140, the user interface 145, and other components via the communication network 120.

[0025] The vehicle 100 includes a plurality of edges 110, typically four wheels 110. Each wheel 110 is rotatable relative to a body 150 of the vehicle 100. The wheel 110 is radially symmetrical and includes two radially symmetrical flanges (not shown) for mounting a tire 115. The wheel 110 can be made of a non-flexible material (e.g., a metal such as steel or aluminum).

[0026] The vehicle 100 includes a tire 115 mounted on each wheel 110. Each tire 115 is an inflatable ring mounted on its respective wheel 110. The tire 115 provides shock absorption and traction. The tire 115 and the wheel 110 define a torus-shaped inflation chamber that can be filled with a pressurized inflation medium, such as air. The inflation chamber has a torus shape. The tire 115 can be made of synthetic or natural rubber or other elastomeric materials that provide sufficient elasticity, durability, and grip. The tire 115 may also include ropes (not shown) running through the elastomeric material and / or chemical compounds added to the elastomeric material.

[0027] The vehicle 100 includes one TPMS 125 for each tire 115. The TPMS 125 can be a direct TPMS sensor (i.e., a pressure sensor). Each TPMS 125 can be positioned to monitor the pressure of the respective inflation chamber defined by the respective tire 115. The TPMS 125 can communicate with the communication network 120 and the computer 105 using short-range wireless signals.

[0028] The vehicle 100 includes one wheel speed sensor 130 for each wheel 110. Each wheel speed sensor 130 can use a magnetic field detector to count interruptions of a magnetic field by a ferromagnetic toothed reluctor ring (also called a tone wheel) arranged on the wheel 110. The wheel speed sensor 130 can be a passive sensor, comprising a ferromagnetic rod with a permanent magnet at one end, wound in wire. The rotation of the reluctor ring induces a current in the wire, which serves as the output of the wheel speed sensor 130. Alternatively, the wheel speed sensor 130 can be an active sensor, which further includes a signal conditioning circuit to encode the output. The output of each wheel speed sensor 130 is a periodic wave (e.g., a sine or square wave) from which the number of wheel 110 revolutions can be counted.

[0029] The speedometer 135 can be any sensor suitable for measuring the speed at which the vehicle 100 is traveling, for example, as is known, a mechanical or eddy current speedometer or a vehicle speed sensor. A vehicle speed sensor can use a magnetic field detector to count interruptions of a magnetic field by a toothed metal disc arranged on a drive shaft of the vehicle 100. Alternatively, the wheel speed sensors 130 can collectively serve as the speedometer 135. For example, the speed of the vehicle 100 can be derived from an average of the wheel speeds.

[0030] The steering angle sensor 140 detects the steering angle of the vehicle 100. The steering angle is the angle formed by the direction in which the front wheels 110 are turned and a longitudinal axis of the vehicle 100. The steering angle sensor 140 can be a position sensor positioned to detect the orientation of the steering wheel 155 of the vehicle 100. For example, the steering angle sensor 140 can be mounted on a steering column (not shown). The steering angle sensor 140 can be, for example, a Hall effect sensor, a rotary encoder, etc. The steering wheel angle reported by the steering angle sensor 140 can be converted into the steering angle of the vehicle 100 according to a known steering ratio.

[0031] The user interface 145 presents information to and receives information from the driver of the vehicle 100. The user interface 145 can be located on a dashboard in a passenger compartment 160 of the vehicle 100 and / or at any location where it is readily visible to the driver. The user interface 145 can include dials, digital displays, screens, speakers, and so on for providing information to the driver, such as familiar elements of a human-machine interface (HMI). The user interface 145 can include buttons, knobs, keypads, a microphone, and so on for receiving information from the driver.

[0032] As a general overview, the computer 105 is programmed to determine, based on wheel speeds, whether any of the tires 115 have low pressure in response to a variety of conditions. These conditions may include at least one TPMS 125 being inactive, the vehicle 100's speed exceeding the vehicle speed threshold, the vehicle 100's steering angle being within a steering angle range, and / or one or more of the vehicle 100's current operating modes being predefined operating modes, as described below. In response to all conditions being met, the computer 105 uses the wheel speeds to determine whether any of the tires 115 have low pressure, as described below.In response to at least one of the conditions not being met, the computer 105 may refrain from using wheel speeds to determine whether any of the tires 115 have low pressure. In this case, the computer 105 may use data from the TPMS 125 (if active) to determine whether any of the tires 115 have low pressure, or the computer 105 may refrain from determining whether any of the tires 115 have low pressure.

[0033] In response to the fact that the TPMS 125 is inactive (e.g., in response to at least one of the TPMS 125 being inactive), the computer 105 can determine, based on wheel rotation speeds, whether any of the tires 115 have low pressure. For example, the computer 105 can determine that one of the TPMS 125 is inactive by receiving a message (e.g., a diagnostic trouble code - DTC) indicating that the TPMS 125 is inactive. As another example, the computer 105 can determine that a TPMS 125 is inactive in response to not receiving data from the TPMS 125 for at least one time threshold (referred to as a first time threshold, as other time thresholds are discussed below). The first time threshold can be chosen to be longer than the rate at which the TPMS 125 sends data.When active, the TPMS 125 can provide a more accurate determination of whether a tire 115 has low pressure.

[0034] The computer 105 can, in response to the vehicle 100 exceeding the vehicle speed threshold, determine, based on wheel speeds, whether any of the tires 115 have low pressure. The computer 105 can receive the speed from the speedometer 135. The vehicle speed threshold can be chosen to be high enough to provide accurate results from the wheel speed sensors 130 and low enough to be exceeded during typical vehicle 100 driving (e.g., 15 mph). For example, the computer 105 can determine, in response to the speed exceeding the vehicle speed threshold for at least one second time threshold, whether any of the tires 115 have low pressure.The second time threshold can be chosen to be long enough to compensate for fluctuations in wheel speeds reported by the wheel speed sensors 130, thereby increasing accuracy.

[0035] In response to the fact that the steering angle of the vehicle 100 is within the steering angle range, the computer 105 can determine, based on the wheel rotation speeds, whether any of the tires 115 have low pressure. The computer 105 can receive the steering angle from the steering angle sensor 140. The steering angle range can be selected to encompass a typical variation of the steering angle when the vehicle 100 is traveling straight ahead. The steering angle range thus includes a straight-ahead steering angle (i.e., the steering angle that occurs when the front wheels 110 are aligned parallel to the longitudinal axis of the vehicle 100). For example, the steering angle range can be between -15° and +15°, with 0° being the straight-ahead steering angle. By using the steering angle range, it can be ensured that the wheels 110 on one side of the vehicle 100 do not cover more ground (and therefore rotate faster) than the wheels 110 on the other side.

[0036] In response to the fact that the current operating mode of the vehicle 100 is a first operating mode, the computer 105 can determine, based on the wheel rotation speeds, whether any of the tires 115 have low pressure. For the purposes of this disclosure, "operating mode" is defined as a data element or record that indicates how one or more components of the vehicle 100 are operated. The vehicle 100 can have a plurality of current operating modes at any given time. Each of the current operating modes can be selected or determined from a set of stored operating modes (e.g., a current operating mode for a component can be selected from a first operating mode, a second operating mode, and a third operating mode).For example, an operating mode can specify whether a traction control system is turned on, so the current operating mode can be either "Traction Control System On" or "Traction Control System Off." In response to the current operating mode being "Traction Control System Off," but not in response to the current operating mode being "Traction Control System On," the computer 105 can determine, based on wheel speeds, whether any of the tires 115 have low pressure. As another example, an operating mode can specify whether the ignition is turned on, so the current operating mode can be "On," "Off," or "Auxiliary Power."The computer 105 can determine, based on wheel speeds, whether any of the tires 115 have low pressure, in response to the current operating mode being "on," but not in response to the current operating mode being "off." As another example, a current operating mode could be either the factory mode (used when the vehicle 100 is being assembled), the transport mode (used when the vehicle 100 is being delivered to a destination), or the driver mode (used for typical driving by the driver). The computer 105 can determine, based on wheel speeds, whether any of the tires 115 have low pressure, in response to the current operating mode being driver mode, but not in response to the current operating mode being factory or transport mode.As another example, the operating mode can indicate whether the parking brake is engaged or disengaged. The computer 105 can determine, based on wheel rotation speeds, whether any of the tires 115 have low pressure in response to the current operating mode being "Parking Brake Off," but not in response to the current operating mode being "Parking Brake On." Using the current operating mode ensures that the vehicle 100 is not in an operating mode that could produce false positive results for low pressure.

[0037] In response to all conditions being met, the computer 105 determines, based on the wheel rotation speeds, whether any of the tires 115 have low pressure. As a general overview, the computer 105 determines whether the difference between the wheel rotation speeds of different wheels 110 exceeds a threshold value. If so, it is assumed that one of the tires 115 has low pressure, and the computer 105 can set a flag in memory indicating the low pressure of tire 115 and issue a message indicating the low pressure of tire 115.

[0038] The computer 105 determines the difference between the wheel speeds of different wheels 110 of the vehicle 100. The difference can be between the fastest and slowest wheel speeds. The fastest and slowest wheel speeds can occur simultaneously. In other words, the fastest wheel speed ω fast (t) at a time t be a maximum value of the four wheel speeds of the respective wheels 110, which was reported at a time t (i.e. ω fast (t) = maxω1(t), ω2(t), ω3(t), ω4(t))). The slowest wheel speed ω slow (t) at a time t can be a minimum value of the four wheel speeds of the respective wheels 110 that was reported at a time t (i.e., ω slow(t) = min(ω1(t), ω2(t), ω3(t), ω4(t))). By using the fastest and slowest wheel speeds, the widest possible dispersion can be ensured, and thus most low-pressure tire situations could be detected (e.g., including one, two, or three low-pressure tires). The difference Δω(t) can be expressed as the fraction of the slowest wheel speed, as in the following expression: Δω(t)=ωfast(t)−ωslow(t)ωslow(t)

[0039] Scaling the difference by the slowest wheel speed allows the differences in wheel speeds at different vehicle speeds to be compared.

[0040] The computer 105 determines whether the difference Δω(t) exceeds the difference threshold ω te exceeds (i.e., Δω(t) > ω teThe differential threshold can be a preset value stored in the memory of computer 105. The differential threshold can be selected to indicate that the pressure of tire 115 at the slowest wheel speed is below the recommended tire pressure for tire 115. In response to the differential exceeding the differential threshold, computer 105 can set the flag in its memory and / or issue a message indicating the low tire pressure of tire 115.

[0041] In response to the difference exceeding the difference threshold, computer 105 can set a flag in memory indicating low tire pressure in tire 115. For example, the flag could be the first value of a binary variable. The first value of the binary variable (e.g., 1) indicates that at least one of the tires 115 has low pressure, and a second value of the binary variable (e.g., 0) indicates that none of the tires 115 have low pressure. Alternatively, the flag could be a diagnostic trouble code (DTC), which may be formatted according to a standard such as On-Board Diagnostics II (OBD-II). According to OBD-II, the format of a DTC is a letter followed by four digits, the combination of which can identify a specific problem with the vehicle 100 (e.g., a fault associated with a vehicle component).

[0042] Computer 105 can output a message indicating low tire pressure in response to the difference exceeding the threshold. For example, computer 105 can output the message when the flag is set (which occurs when the difference exceeds the threshold). Computer 105 can output the message by activating user interface 145. Computer 105 can also activate user interface 145 to illuminate a light on the dashboard of vehicle 100. This light could be a low tire pressure warning light. Alternatively or additionally, computer 105 can activate user interface 145 to emit a sound, such as a bell, through a speaker connected to user interface 145.Alternatively or additionally, the computer 105 can activate the user interface 145 to display a message on a screen of the user interface 145. The message can indicate that one of the tires 115 has low pressure.

[0043] The flag can persist in memory for one ignition cycle of vehicle 100. For example, the binary variable can retain its value, or the DTC can remain set, if vehicle 100 is switched off and then restarted. Computer 105 can be programmed to output a message indicating low tire pressure in response to vehicle 100 starting with the flag set. This reminds the driver of the low pressure until the flag is removed.

[0044] Computer 105 can be programmed to remove the flag in response to the fact that the difference for at least one third time threshold after the flag has been set is below the difference threshold. The third time threshold can be chosen to be longer than a random fluctuation in tire pressure. The third time threshold can be the same as the second time threshold or different from it. Computer 105 can determine that the difference for at least the third time threshold after the flag has been set is below the difference threshold (i.e., Δω(t) < ω). te is true for t of t flag are flag + T, where t flag(the time at which the flag is set, and T is the third threshold). Computer 105 can remove the flag, for example, by setting the binary variable to the second value or by removing the DTC. Computer 105 can also remove the flag in response to the fact that the TPMS 125 are active and indicate that the tires 115 do not have low pressure.

[0045] Fig.Figure 2 is a flowchart illustrating an example process 200 for checking for low tire pressure 115. The computer 105's memory contains executable instructions for carrying out the steps of process 200, and / or programming may be implemented in structures such as those mentioned above. As a general overview of process 200, the computer 105 receives data. When the conditions are met (i.e., at least one of the TPMS 125 is inactive, the current operating modes are in their respective first operating modes, the steering angle is within the steering angle range, and the vehicle speed 100 exceeds the vehicle speed threshold for at least the second time threshold), the computer 105 determines the difference between the wheel speeds.In response to the difference exceeding the difference threshold, computer 105 sets the flag and issues a message indicating low tire pressure (115). Once the flag is set, computer 105 removes the flag if the difference remains below the difference threshold for at least three time intervals after the flag was set.

[0046] The process 200 begins at a block 205, where the computer 105 receives data from the TPMS 125 (if active), the wheel speed sensors 130, the speedometer 135, the steering angle sensor 140 and other components which indicate the current operating modes.

[0047] Next, in decision block 210, computer 105 determines whether the TPMS 125 are active, as described above. If the TPMS 125 are active, process 200 terminates. If at least one TPMS 125 is inactive, process 200 proceeds to decision block 215.

[0048] In decision block 215, computer 105 determines whether the current operating modes of vehicle 100 are in their respective first operating modes, as described above. If at least one current operating mode is not in its respective first operating mode, process 200 terminates. If the current operating modes are in their respective first operating modes, process 200 proceeds to decision block 220.

[0049] In decision block 220, computer 105 determines whether the steering angle is within the steering angle range, as described above. If the steering angle is outside the steering angle range, process 200 terminates. If the steering angle is within the steering angle range, process 200 proceeds to decision block 225.

[0050] In decision block 225, computer 105 determines whether the speed at which vehicle 100 is traveling exceeds the vehicle speed threshold, as described above. If the speed is below the speed threshold, process 200 terminates. If the speed exceeds the speed threshold, process 200 proceeds to decision block 230.

[0051] In decision block 230, computer 105 determines whether the vehicle speed has exceeded the speed threshold for at least the second time threshold. If the speed exceeds the vehicle speed threshold for less than the second time threshold, process 200 returns to block 205 to continue receiving data for a longer period. If the speed exceeds the speed threshold for at least the second time threshold, process 200 proceeds to block 235.

[0052] In block 235, the computer 105 determines the difference between the wheel speeds of different wheels 110 of the vehicle 100, as described above.

[0053] Next, at decision block 240, computer 105 determines whether the difference exceeds the difference threshold, as described above. If the difference is below the difference threshold, process 200 terminates. If the difference exceeds the difference threshold, process 200 proceeds to block 245.

[0054] At block 245, the computer sets the flag 105 and outputs the message indicating the low tire pressure 115, as described above.

[0055] Next, at decision block 250, computer 105 again determines the difference and ascertains whether the difference is below the difference threshold for at least the third time threshold, as described above. If the difference exceeds the difference threshold or is below it for fewer than the third time threshold, process 200 remains at decision block 250 to continue checking the difference against the difference threshold. If the difference is below the difference threshold for at least the third time threshold, process 200 moves on to block 255.

[0056] At block 255, computer 105 removes the flag, as described above. After block 255, process 200 terminates.

[0057] In general, the described computing systems and / or devices can use any of a range of computer operating systems, including, but not limited to, versions and / or variants of the Ford Sync® application, the AppLink / Smart Device Link middleware, the Microsoft Automotive® operating system, the Microsoft Windows® operating system, the Unix operating system (e.g., the Solaris® operating system, distributed by Oracle Corporation in Redwood Shores, California), the AIX UNIX operating system, distributed by International Business Machines in Armonk, New York, the Linux operating system, the Mac OSX and iOS operating systems, distributed by Apple Inc. in Cupertino, California, the BlackBerry OS, distributed by Blackberry, Ltd. in Waterloo, Canada, and the Android operating system, developed by Google, Inc. and the Open Handset Alliance, or the QNX® CAR Platform for Infotainment, offered by QNX Software Systems.Examples of computing devices include, without limitation, an onboard vehicle computer, a computer workstation, a server, a desktop, notebook, laptop or handheld computer, or any other computing system and / or device.

[0058] Computing devices generally contain computer-executable instructions, which can be executed by one or more computing devices, such as those listed above. Computer-executable instructions can be compiled or interpreted by computer programs created using a variety of programming languages ​​and / or technologies, including, but not limited to, Java™, C, C++, Matlab, Simulink, Stateflow, Visual Basic, JavaScript, Perl, HTML, and others, either alone or in combination. Some of these applications can be compiled and executed on a virtual machine, such as the Java Virtual Machine, the Dalvik Virtual Machine, or similar. Generally, a processor (e.g., a microprocessor) receives instructions (e.g., from memory, a computer-readable medium, etc.).) and executes these instructions, thereby carrying out one or more processes, including one or more of the processes described in this document. Such instructions and other data can be stored and transmitted using a variety of computer-readable media. A file in a computing device is generally a collection of data stored on a computer-readable medium, such as a storage medium, random-access memory, etc.

[0059] A computer-readable medium (also called a processor-readable medium) is any non-volatile (e.g., physical) medium involved in providing data (e.g., instructions) that can be read by a computer (e.g., by a computer's processor). Such a medium can take many forms, including both non-volatile and volatile media. Instructions can be transmitted through one or more transmission media, including optical fibers, wires, and wireless communication, as well as internal components that comprise a system bus connected to a computer's processor. Common forms of computer-readable media include, for example, RAM, PROM, EPROM, FLASH EEPROM, any other memory chip, memory cartridge, or any other medium from which a computer can read.

[0060] Databases, data repositories, or other data storage devices described herein may include various types of mechanisms for storing, accessing, and retrieving different types of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), a non-relational database (NoSQL), a graph database (GDB), and so on. Each such data storage device is generally contained within a computing device that uses a computer operating system, such as one of those listed above, and is accessed in one or more of a variety of ways over a network. A file system can be accessed by a computer operating system and may contain files stored in various formats.An RDBMS generally uses the Structured Query Language (SQL) in addition to a language for creating, storing, editing and executing stored procedures, such as the PL / SQL language mentioned above.

[0061] In some examples, system elements may be implemented as computer-readable instructions (e.g., software) on one or more computing devices (e.g., servers, personal computers, etc.) stored on computer-readable media associated with them (e.g., disks, memory, etc.). A computer program product may include such instructions stored on computer-readable media for performing the functions described in this document.

[0062] In the drawings, identical reference symbols denote the same elements. Furthermore, some or all of these elements could be modified. Regarding the media, processes, systems, procedures, heuristics, etc., described herein, it is understood that although the steps of such processes, etc., have been described as following a specific, ordered sequence, such processes could be implemented in practice, with the described steps being carried out in an order that differs from the sequence described in this document. It is further understood that certain steps could be performed simultaneously, other steps added, or certain steps described herein omitted.

[0063] The revelation has been described in an illustrative manner, and it is understood that the terminology used is intended to be descriptive and not restrictive. The use of "in response to" and "in determining," etc., indicates a causal relationship, not merely a temporal one. Terms such as "front," "forward," "longitudinal," "rear," "behind," "left," "right," "across," "upward," "downward," "vertical," etc., are understood in relation to Vehicle 100. The adjectives "first," "second," and "third" are used in this writing as identifiers and are not intended to indicate any meaning, sequence, or quantity. In light of the foregoing teachings, many modifications and variations of the present revelation are possible, and the revelation may be implemented differently than specifically described.

[0064] According to the present invention, a computer is provided comprising a processor and a memory, wherein instructions are stored in the memory which can be executed by the processor to: determine a difference between wheel speeds of different wheels of a vehicle in response to the fact that a speed at which the vehicle is traveling exceeds a vehicle speed threshold; and output a message indicating low pressure of a tire of one of the wheels in response to the difference exceeding a difference threshold.

[0065] According to one embodiment, the instructions also include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and a steering angle of the vehicle being within a steering angle range.

[0066] According to one embodiment, the steering angle range includes a straight-ahead steering angle.

[0067] According to one embodiment, the instructions also include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and the vehicle's tire pressure monitoring system being inactive.

[0068] According to one embodiment, the vehicle includes a tire pressure monitoring system for each tire; and the instructions further include instructions for determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and at least one of the tire pressure monitoring systems being inactive.

[0069] According to one embodiment, the instructions also include instructions for determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold for at least one time threshold.

[0070] According to one embodiment, the instructions further include instructions for determining the difference between the wheel speeds in response to the speed exceeding the vehicle speed threshold and the current operating mode of the vehicle being a first operating mode.

[0071] According to one embodiment, the difference is between the fastest wheel speed and the slowest wheel speed.

[0072] According to one embodiment, the fastest wheel speed and the slowest wheel speed occur simultaneously.

[0073] According to one embodiment, the difference is expressed as a proportion of the slowest wheel speed.

[0074] According to one embodiment, the instructions also include instructions for setting a flag in the memory in response to the difference exceeding the difference threshold.

[0075] According to one embodiment, the instructions further include instructions for issuing the message indicating low tire pressure in response to the vehicle being started with the flag set.

[0076] According to one embodiment, the instructions also include instructions for removing the flag in response to the fact that the difference is below the difference threshold for at least one time threshold after the flag has been set.

[0077] According to the present invention, a method comprises: determining a difference between the wheel speeds of different wheels of a vehicle in response to the vehicle exceeding a vehicle speed threshold; and outputting a message indicating low tire pressure of one of the wheels in response to the difference exceeding a difference threshold.

[0078] In one aspect of the invention, the method involves determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold and a steering angle of the vehicle being within a steering angle range.

[0079] In one aspect of the invention, the method involves determining the difference between the wheel speeds in response to the fact that the speed exceeds the vehicle speed threshold and the vehicle's tire pressure monitoring system is inactive.

[0080] In one aspect of the invention, the vehicle includes a tire pressure monitoring system for each tire; and the method further comprises determining the difference between the wheel speeds in response to the fact that the speed exceeds the vehicle speed threshold and at least one of the tire pressure monitoring systems is inactive.

[0081] In one aspect of the invention, the method involves determining the difference between the wheel speeds in response to the vehicle speed exceeding the vehicle speed threshold for at least one time threshold.

[0082] In one aspect of the invention, the method involves determining the difference between the wheel speeds in response to the fact that the speed exceeds the vehicle speed threshold and a current operating mode of the vehicle is a first operating mode.

[0083] One aspect of the invention is the difference between the fastest wheel speed and the slowest wheel speed.

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