Tire pressure monitoring device with range limitation for communication

Abstract

A tire pressure monitoring device is provided that implements a range limit on communications. Tire monitoring devices, tire monitoring systems, and methods are described. In one example, a tire monitoring device includes a wireless interface having range determination capability and a processor. The processor is configured to receive a command from a second device of a tire monitoring system via the wireless interface, determine a range to the second device, and execute the command if the range to the second device is less than a predetermined threshold.

Description

Technical Field

[0001] This disclosure relates to tire monitoring systems and methods of operation thereof. In the example, this disclosure relates to an aircraft tire monitoring system, such as an aircraft tire pressure monitoring system. Background Technology

[0002] Checking tire pressure is an important part of vehicle maintenance. Tire pressure should be maintained at the predetermined pressure to ensure the tires function as the manufacturer intended. Incorrect tire pressure can lead to tire failure, potentially bursting and causing damage and / or loss of control of the vehicle. Because tires on aircraft landing gear experience high speeds, their pressure should be checked regularly, possibly daily or more frequently. Manually checking tire pressure takes time, and minimizing that time is beneficial.

[0003] A proposal has been made to automate tire pressure measurement by including a sensor in the wheel, which can then be wirelessly queried for the tire pressure measurement. This could reduce the time required compared to manual reading, but security measures such as encryption keys are needed because the wireless channel is broadcast outside the aircraft. Summary of the Invention

[0004] According to a first aspect, a tire monitoring device for use in a tire monitoring system is provided. The tire monitoring device includes: a wireless interface having range determination capability; and a processor. The processor is configured to: receive a command from a second device of the tire monitoring system via the wireless interface; determine the range to the second device; and execute the command if the range to the second device is less than a predetermined threshold.

[0005] According to a second aspect, a tire monitoring device for use in a tire monitoring system is provided. The tire monitoring device includes: a wireless interface with range determination capability; and a processor. The processor is configured to: receive data from a second device of the tire monitoring system via the wireless interface; determine the range to the second device; and reject the data if the range to the second device is greater than a predetermined threshold. Optionally, the processor is configured to: receive a command from a third device of the tire monitoring system via the wireless interface; determine the range to the third device; and execute the command if the range to the third device is less than a predetermined threshold.

[0006] Alternatively, the tire monitoring device is configured to be mounted on the wheels of the aircraft.

[0007] According to a third aspect, a tire monitoring system is provided, which includes a plurality of tire monitoring devices having or not having optional features as discussed above.

[0008] Optionally, the tire monitoring system includes a control device that includes a wireless communication interface with range determination capability.

[0009] According to a fourth aspect, a method for a wireless tire monitoring device is provided. The method includes: receiving a command from a second device of a tire monitoring system via a wireless interface; determining a range to the second device; and executing the command if the range to the second device is less than a predetermined threshold.

[0010] According to a fifth aspect, a method for a wireless tire monitoring device is provided. The method includes: receiving data from a second device of a tire monitoring system via a wireless interface; determining a range to the second device; and rejecting the data if the range to the second device is greater than a predetermined threshold. Optionally, the method further includes: receiving a command from a third device of the tire monitoring system via a wireless interface; determining a range to the third device; and executing the command if the range to the third device is less than a predetermined threshold.

[0011] Alternatively, in any of the above aspects, the wireless interface includes an ultra-wideband (UWB) interface.

[0012] Optionally, in any of the above aspects, the predetermined threshold is less than or equal to 40m. Attached Figure Description

[0013] Figure 1 A schematic diagram of a tire monitoring system according to a first example of the present invention is shown.

[0014] Figure 2 It shows the use of in Figure 1 The example shows a schematic diagram of the tire monitoring device used.

[0015] Figure 3 It shows the use of in Figure 1 A schematic diagram of the control device used in the example.

[0016] Figure 4 It shows the use of in Figure 1 The example shows a schematic diagram of the configuration device used.

[0017] Figure 5 A schematic diagram of a tire pressure sensor network installed in an aircraft is shown.

[0018] Figure 6 It shows that it can be used with Figure 1 The example uses a flowchart of the tire pressure check process.

[0019] Figure 7 It shows that it can be made by Figure 2 A flowchart of the tire pressure check process used in tire monitoring devices.

[0020] Figure 8 A flowchart is shown for the process of imposing communication range restrictions on received commands or data. Detailed Implementation

[0021] In the following description, for illustrative purposes, many specific details of certain examples are set forth. References to "example" or similar language in the specification mean that a particular feature, structure, or characteristic described in connection with the example is included in at least one example, but not necessarily in other examples.

[0022] Some of the methods and systems described herein relate to the operation of sensor networks in aircraft, such as networks of tire monitoring devices. In the examples described herein, the reference to “aircraft” includes all types of aircraft, such as fixed-wing aircraft like military or commercial aircraft or unmanned aerial vehicles (UAVs) and rotorcraft like helicopters.

[0023] According to the examples in this paper, a tire monitoring device, which forms part of a tire monitoring system, provides a status indication on its own surface. For example, the status indication can be provided by an indicator light, where the color of the light conveys the status information. Confirmation of the status indicated on the tire monitoring device is provided as input to a control unit, where this input can be compared with status data received from the tire monitoring device itself. In this way, various human factors can be addressed during system use. In the case where the input comes from a user of the system, this means that the user must pay attention to the indication on the device itself, not just the information displayed on the control unit. This is important when the indication on the tire monitoring device has been confirmed to meet the expected Development Assurance Level (DAL) while the indication on the control unit has not. This also addresses human error factors, such as seeing the wrong aircraft when several aircraft are very close. As another advantage, errors can be identified when user input does not match what is displayed on the device itself.

[0024] In some examples, once the status of the indicator on the tire monitoring device is confirmed by input (in other words, both the indicator on the tire monitoring device and the input are determined to represent the same state), the indicator on the tire monitoring device can be turned off. This results in power savings because the indicator does not need to be active for extended periods. For example, the indicator could be a high-intensity LED that is visible even in bright sunlight. An example of a high-intensity LED is the Vishay TLCR5200, a commercially available red LED from Vishay. This LED typically has a luminous intensity of 4000 mcd but dissipates 135 mW; therefore, useful energy savings can be achieved by turning it off early before the overall system timeout. Such energy savings can be particularly useful when the tire monitoring device's power supply has limited energy reserves (e.g., a battery), as this directly impacts the lifespan of the tire monitoring device.

[0025] Example Tire Monitoring System

[0026] Figure 1 A schematic diagram of a tire monitoring system is shown, in this case, a pressure sensor system according to a first example. The system includes multiple tire monitoring devices 10, a control device 12, and a configuration device 14, all of which are configured to communicate wirelessly. The tire monitoring devices are installed on each wheel of a vehicle, in this case, an aircraft (see below). Figure 5 (To be explained in more detail). The control device 12 is separate from the tire pressure sensor 10 and may be a dedicated control device that functions only in the tire pressure sensor system, or it may be a computing device that can be used for other purposes besides the tire pressure sensor system. Example computing devices include mobile devices such as laptops, tablets, cellular phones, and wireless communication devices.

[0027] Figure 1Wireless communication in a tire pressure sensor system can use a local area network (LAN) or a personal area network (PAN) and can have any suitable topology, including centralized systems and mesh wireless systems. In a centralized system, a single device can be designated as the master device to coordinate communication, or one or more additional wireless access points, gateways, or controllers (not shown) can be used. In some examples, the tire monitoring device 10, control device 12, and configuration device 14 can all communicate using the same wireless technology and form a single network. In other examples, one or more of the tire monitoring device 10, control device 12, and configuration device 14 can be isolated from other components in the system. Such isolation can be provided in software, for example, by providing a suitable firewall and / or using different network IDs and encryption keys. Such isolation can also be provided by hardware, for example, through different wireless communication technologies. Both hardware isolation and software isolation can be combined. For example, in Figure 1 In this system, the control unit uses a different wireless communication technology than that used in this configuration to communicate with the tire sensing device, which can improve the system's safety.

[0028] Figure 2 It shows the use of in Figure 1 A schematic diagram of a tire monitoring device 10 used in a tire pressure sensor system. The tire monitoring device 10 is configured for mounting on a wheel, for example, via a mechanical connection to an opening on the wheel that provides access to the tire. The tire monitoring device 10 includes a processor 200, a wireless communication interface 202, an indicator 204, a power supply 206, a pressure sensor 208, a temperature sensor 209, a first storage device 210, and a second storage device 211.

[0029] Processor 200 can be any suitable processing device including a microprocessor having one or more processing cores. In use, processor 200 coordinates and controls other components and is operable to read computer program instructions and data from and / or write computer program instructions and data to storage devices 210, 211. In some examples, the processor may be optimized for low-power operation or have at least one processing core optimized for low-power operation.

[0030] Wireless communication interface 202 is connected to processor 200 and is used to send and receive data from other devices in the tire pressure sensor system. In this example, the wireless communication interface includes two transceivers 212 and 214, which use different wireless technologies. The first transceiver 212 is provided for communication over relatively long distances of approximately 50 m or 100 m. For example, the first transceiver can use communication standards suitable for mobile devices or Wireless Avionics Internal Communication (WAIC) standards, such as IEEE 802.11 (Wi-Fi), IEEE 802.15.1, and IEEE 802.15.4 in the 2.4 GHz or 5 GHz Industrial, Scientific and Medical (ISM) bands. The first transceiver also includes an encryption module for encrypting transmitted data and decrypting received data, for example, according to Advanced Encryption Standard (AES) using a pre-shared key. The second transceiver 214 is provided for communication over relatively short distances. For example, the second transceiver 214 can use standards according to IEEE 802.15, such as IEEE 802.15.4, RFID, or Near Field Communication (NFC). The second transceiver can operate within a range of less than 5m, less than 3m, less than 1m, less than 50cm, less than 25cm, less than 10cm, less than 5cm, less than 1cm, or where contact between devices is required. Similar to the first transceiver 212, the second transceiver 214 also includes an encryption module for encrypting transmitted data and decrypting received data.

[0031] In some examples, a single wireless transceiver can be provided in the wireless communication interface. In this case, the single transceiver can be used for relatively short-range or relatively long-range communication, or the range can be adjusted as needed (e.g., by controlling the transmission power).

[0032] Indicator 204 is connected to and controlled by processor 200 to provide indication to the user of the tire pressure sensor system. In this example, the indicator is an LED, but in other examples, the indicator is another form of light, a display such as an LCD or e-ink display, or any other form of visual indication. In other examples, the indicator is an auditory indicator, such as a buzzer, pager, speaker, or any other sound-generating component. In other examples, the indicator may include both auditory and visual indication components. The indicator provides at least a first indication and a second indication, such as emitting light of a first color and emitting light of a second color. Other indications may also be provided, such as continuous or flashing light. The tire monitoring device has a housing (not shown), and indicator 204 may provide indication external to the housing, for example, the LED may be mounted externally to the housing or visible through the housing, or it may be capable of emitting sound from inside the housing.

[0033] Power source 206 provides power to components in the sensing device. Power source 206 can be a battery, such as a lithium battery. In this example, the power source is a lithium battery with sufficient power to enable the sensor to operate under normal conditions for approximately 2 to 3 years. In other examples, the power source may include, for example, a power harvesting system that collects vibrations and / or electromagnetic radiation to charge a capacitor or battery, which is then used to power the device.

[0034] In use, wireless sensing devices can remain in "sleep" or low-power mode for most of their operational lifespan, in which most components, except for the processor and wireless communication interface, are powered down. This conserves battery life. For example, a tire monitoring device can default to low-power mode, listening for commands to measure or report tire pressure. Since tire pressure readings may be relatively infrequent, perhaps as little as once every 10 days, every 5 days, every 3 days, or daily, this provides useful power savings. In other examples, pressure can be sensed more frequently, such as every 10 minutes, every 15 minutes, every 20 minutes, every 30 minutes, every hour, or every 2 hours, and the pressure can be stored for use in trend monitoring.

[0035] Pressure sensor 208 is connected to processor 200 and can be any suitable sensor for measuring pressure, such as a capacitive sensor. Similarly, temperature sensor 209 is connected to processor 200 and can be any suitable sensor for measuring temperature, such as a thermocouple. Temperature sensor 209 can be configured to measure the temperature of the wheel or directly measure the temperature of the gas inside the tire. In the case where temperature sensor 209 measures the temperature of the wheel, the wheel temperature can be processed to determine the temperature of the gas inside the tire. For example, an algorithm or lookup table can be used.

[0036] The connection between pressure sensor 208 and temperature sensor 209 and processor 200 can be digital, providing a digital representation of the measured pressure and / or temperature from an analog-to-digital converter (ADC) within the sensors themselves, or the connection can be analog, in which case the processor may include the ADC to sample the received signals. Including both a pressure sensor and a temperature sensor can help determine a temperature-compensated pressure value. While this example includes both a pressure sensor and a temperature sensor, other examples may include only a pressure sensor, or may include other sensors.

[0037] This example includes two storage device elements 210 and 211. In this example, storage device 210 is a non-volatile, rewritable storage device, such as flash memory, that can retain data without requiring power. Other examples may include volatile storage devices that are powered by a power source or a combination of read-only and rewritable storage devices. Storage device 210 is connected to processor 200 and is used to store both computer program instructions for execution by the processor and data, such as data from pressure sensor 208 or data received via wireless communication interface 202. In some examples, storage device 210 may store historical records of pressure readings sensed by pressure sensor 208 and / or temperature readings sensed by temperature sensor 209. For example, readings from the previous ten days may be stored, wherein once the storage device is full, the most recent data replaces the oldest data.

[0038] Storage device 211 is a secure storage device with restricted write and / or read access, for example, accessible only by certain processes running on processor 200. Configuration data, such as wireless encryption keys, may be stored in storage device 211. In other examples, a single storage device may be provided, or storage devices 210 and 211 may be provided in a single physical device, wherein there is a logical division between storage device 210 and storage device 211.

[0039] Figure 3 It shows the use of in Figure 1 The example shows a schematic diagram of the control device 12 used. The control device 12 includes a processor 300, a display 302, an input system 304, a power supply 306, a wireless interface 308, a storage device 310, and a wired communication interface 312. In this example, the control device is a mobile device such as a cellular phone or a tablet computer.

[0040] Processor 300 can be any suitable processing device that may include one or more processing cores, such as a multi-purpose microprocessor, system-on-a-chip, or system-in-package. Processor 300 is connected to display 302, such as an LCD, OLED, or e-ink display, to display information to the user of the control device.

[0041] In this example, input system 304 includes a touchscreen interface, allowing a user to interact with the control device by touching user interface elements on the screen. In addition to the touchscreen, input system 304 may also include one or more buttons and other input devices such as a microphone for voice recognition and a camera for image input. Other examples may not include a touchscreen interface.

[0042] The control unit is powered by power supply 306, which in this example is a rechargeable lithium-ion battery. Other examples may use alternative power sources, such as other battery technologies, trunk power, or energy harvesting such as solar power.

[0043] A wireless interface 308 is included for communication between the control device 12 and other devices in the tire pressure sensor system. In this example, a single wireless interface 308 is provided, configured to communicate with the tire monitoring device 10. For example, a relatively long-range wireless communication technology, such as one conforming to IEEE 802.15.1, IEEE 802.15.4, or IEEE 802.11, can be used. This enables the control device 12 to interact with the tire monitoring device from a relatively long distance.

[0044] In other examples, a plurality of wireless communication interfaces or transceivers may be provided to the control device, which operate using at least two of different wireless technologies such as IEEE 802.15.1, IEEE 802.15.4, IEEE 802.11 (Wi-Fi_33), WAIC, RFID, and NFC. For example, the control device may have two transceivers, one of which has a longer communication range than the other.

[0045] Storage device 310 includes non-volatile elements such as flash memory and volatile elements such as RAM. The non-volatile elements are used to store operating system software and application software. In this example, the control device runs standard operating system software and is loaded with application software for interacting with the tire pressure sensor system. To restrict access to the tire pressure sensor network, the application software may be provided from a secure source and not publicly available, and / or require credentials to be entered before operation.

[0046] A wired communication interface 312 is provided for connection to a computing system. The wired communication interface 312 can be, for example, a serial data connection such as a Universal Serial Bus (USB), a parallel data connection, or a network connection such as Ethernet. The wired communication interface 312 enables the control device to transmit values ​​and / or other status information read from the tire monitoring device to the computing system for example, to store long-term trends and assist in fleet management. Alternatively or additionally, a wireless communication interface 308 can be used to communicate with the computing system. In some examples, the control device may not include a wired communication interface.

[0047] Figure 4 It shows the use of in Figure 1The example shows a schematic diagram of the configuration device 14 used. Configuration device 14 typically includes the same components as control device 12: processor 400, display 402, input system 404, power supply 406, wireless interface 408, storage device 410, and wired communication interface 412, and these components are generally the same as those described above regarding the control device unless otherwise described below. In this example, the configuration device is a mobile device, but is limited to operating only with the tire monitoring system. For example, the configuration device could be a computing device or tablet computer capable only of running software for interacting with the tire monitoring system.

[0048] In this example, the wireless communication interface 408 in the configuration device is a relatively short-range communication system, such as IEEE 802.15.1, IEEE 802.15.4, NFC, or RFID. This allows the configuration device to act as an additional authentication factor when configuring the tire monitoring device; for example, the tire monitoring device may respond only to configuration commands received from the configuration device or only to configuration commands received from the control device after receiving commands from the configuration device.

[0049] In other examples, the configuration apparatus may include multiple wireless communication interfaces or transceivers. For example, the configuration apparatus may include transceivers for relatively short-range communication as discussed above, as well as transceivers for relatively long-range communication, such as transceivers compliant with IEEE 802.11.

[0050] The wired communication interface 412 in the configuration device can be used to provide information to the configuration device in a secure manner, such as enabling the updating of some encryption keys via a wired interface, such as a serial data connection, instead of a wireless interface.

[0051] In some examples, configuration device 14 may be omitted and replaced by control device 12. Control device 12 may include a short-range wireless communication interface, such as a short-range wireless communication interface compliant with IEEE 802.15.1, IEEE 802.15.4, RFID, or NFC. Application software may be loaded onto the control device in such a way that the control device can also be used as an additional authentication factor, possibly by maintaining a cryptographic key that can only be accessed with appropriate credentials to control the operation of the short-range wireless communication interface used for transmitting configuration commands. In these examples, separate application software may be provided on the control device, which can be executed to enable the control device to function as a configuration device.

[0052] Figure 5A schematic diagram of a tire pressure sensor network installed in an aircraft is shown. The aircraft 500 includes a fuselage 510, wings 520, main landing gear 530, and nose landing gear 540. According to examples, the aircraft 500 includes a sensor network according to any of the examples described herein. The aircraft 500 can be used in conjunction with any of the methods described herein. According to examples, multiple wireless nodes are distributed at various locations around the aircraft 500, such as in the landing gears 530, 540, and wings 520, and in the fuselage 510. Tire monitoring devices are installed on each wheel of the main landing gear 530 and nose landing gear 540.

[0053] In the example, the tire monitoring device 10 also communicates with the cockpit system to provide tire pressure information to the pilot in the cockpit. In these examples, the cockpit console can also function as a control device.

[0054] Example tire pressure check process

[0055] Figure 6 It shows that it can be used with Figure 1 The flowchart illustrates the tire pressure check process used in conjunction with the example. First, at box 602, the user initiates the tire monitoring control application on the control device 12. During application initialization, the control device checks whether the wireless communication interface 308 used for communicating with the monitoring device is active, and prompts the user to activate it if the wireless communication interface 308 is inactive.

[0056] Next, at box 604, the control device scans for tire monitoring devices within range. For example, the control device may issue a probe signal via a wireless communication interface, causing any tire monitoring device within range to respond according to its vehicle identifier—such as the tail identifier of the aircraft to which the tire monitoring device is attached. The scan may include establishing direct point-to-point contact with each tire monitoring device, or establishing contact through a network of tire monitoring devices, such as through any device in an access point, master unit, or mesh network. The scan may include waking the tire monitoring devices from low-power mode. The scan may include communicating with the sensor network using a secure network key.

[0057] Depending on the communication range and location, tire monitoring devices associated with more than one vehicle may be detected. For example, several aircraft may be located in the same hanger within the range of the control unit. Next, at box 606, it is determined whether an identifier should be automatically selected without input. For example, the application may store configuration options for whether an identifier should be automatically selected. If automatic selection is not required, the process continues to box 608. If automatic selection is required, the process continues to box 612. In some examples, box 606 is not included. In these examples, the process may continue by manual or automatic selection as described below.

[0058] For manual selection, at box 608, the control device displays the identifier of the detected vehicle. At box 610, input of the selected identifier is received, for example, based on the user's selection of the desired identifier.

[0059] For automatic selection, at box 612, a vehicle identifier is automatically selected from the identifiers indicated in the received responses. This can be achieved in several ways. For example, in the case where each tire monitoring device in the range responds individually to the control device, at least two responses may come from tire monitoring devices associated with the same vehicle identifier. In that case, the vehicle identifier associated with the largest number of responses can be automatically selected, as that is likely the vehicle closest to the control device that requires pressure measurement. In another example, the vehicle identifier of the tire monitoring device closest to the control device can be selected, such as a response with a maximum received signal strength indication (RSSI). In yet another example, all detected tire monitoring devices may be associated with the same vehicle identifier, in which case that vehicle identifier is selected.

[0060] Next, at box 614, commands are sent to the tire monitoring devices corresponding to the selected identifier to instruct them to read the pressure and report to the control unit. For example, they can perform actions as shown in the following reference. Figure 7 The process described.

[0061] A response is received from the tire monitoring device at box 616, and these responses are displayed on the control device at box 618. The pressure display may include a numerical value and a status indication such as "normal (OK)" or "low pressure" or both.

[0062] At box 620, a cross-check can be performed on the received data to ensure data consistency. Then the process ends.

[0063] exist Figure 6Throughout the process, communication between the control device and the sensor device can be secure, for example, through network key encryption. The network key used for communication with the control device can be different from the network key used for communication with the sensor device to enhance system security.

[0064] When exchanging security keys, security can be enhanced by using wireless communication technologies with limited transmission distances, such as the 802.11 (Wi-Fi) standard, which allows transmission over distances of 50 meters or more in unobstructed spaces. In some examples, security can be improved by reducing transmission power or using low-range technologies such as NFC or RFID when transmitting encryption keys, compared to the transmission of the encrypted data itself, which requires closer proximity for the initial key exchange. Distance-bounding techniques can also be introduced, where, when combined with ultra-wideband radio communication, the distance between communicating devices can be securely measured to ensure that interactions occur within the secure perimeter of the devices, as will be discussed below. Figure 8 Further discussion.

[0065] Figure 7 It shows that it can be made by Figure 2 A flowchart of the tire pressure checking process used by the tire monitoring device is provided. This process offers additional assurance and fault tolerance to the pressure measurements from the system, such as preventing malfunctions or errors in the control unit. Through this process, the monitoring device provides an indication of tire pressure status using its indicators, independent of the control unit. In some examples, the monitoring device's indication of tire pressure status may have a higher Development Assurance Level (DAL) than the indication provided on the control unit. For example, while the control unit may be used to initiate tire pressure measurements and provide the user with convenient means of understanding the measurement results, it may not be DAL certified, whereas the operation of the monitoring device providing an indication using its indicators can be certified as Development Assurance Level B. This allows the system to operate with a variety of control units because, while DAL certification is not required for those units, it ensures that the system as a whole meets the required safety standards. Similarly, in some examples, the monitoring device may have a higher Security Assurance Level (SAL) than the control unit.

[0066] First, at box 702, the tire monitoring device receives a command from the control unit via a wireless communication interface to check the pressure. In response, at box 704, the processor uses a pressure sensor to measure the pressure in the tire. Then, in box 706, the measured pressure is compared to a reference pressure to determine if the tire has low pressure. In this example, low pressure occurs if the pressure sensed by the pressure sensor is less than 89% of the reference pressure. Other examples may determine low pressure when the measured pressure is less than 95%, less than 90%, or less than 85% of the reference pressure. Other examples may determine low pressure when the measured pressure is at least about 207 kPa (about 30 psi) lower than the reference pressure. Other examples may determine low pressure when the measured pressure is at least about 138 kPa (about 20 psi) or about 69 kPa (about 10 psi) lower than the reference pressure. If low pressure is detected, execution proceeds to box 708; otherwise, execution proceeds to box 712.

[0067] At box 708, the processor uses an indicator, for example, by providing a continuous red light for a predetermined period of time to indicate a fault condition. For example, the predetermined period could be 5 minutes, 2 minutes, 1 minute, or 30 seconds. At box 712, the processor also again utilizes a wireless communication interface to broadcast the fault indication to other tire monitoring devices.

[0068] At block 712, the processor checks whether any fault messages from other tire monitoring devices have been received via the wireless communication interface. Such fault messages can be received directly from other tire monitoring devices or through a hub or access point. In this example, such fault messages are received without prior request after a command is received in block 704. In other examples, fault messages can be received in response to a status query sent by one tire monitoring device to another. If any fault message is received, execution proceeds to block 714, where the processor uses an indicator to display the fault condition. For example, the fault indicator can be the same as the one used in block 708. In other examples, the fault indicator can be different from the one used in block 708, for example, a second fault indicator such as flashing a red light for a predetermined period. By using the second fault indicator, the tire monitoring device can indicate a fault in another tire but signal that its own measured pressure is not low.

[0069] If no fault message is received at box 712, execution proceeds to box 716, where the processor provides an "OK" indication using an indicator. This can be done, for example, by providing a continuous green light for a predetermined period of time. The predetermined period could be 5 minutes, 2 minutes, 1 minute, or 30 seconds. In this way, the "OK" indication is given only if all tire monitoring devices have determined that the pressure of their associated tires is not low and they have not received any fault indications from other tire monitoring devices.

[0070] Finally, at box 718, in response to a command, the measured tire pressure data is transmitted to the control unit. This data may include other information, such as stored reference pressure, determined status, and wheel position. The transmission of additional information allows for verification of the correct operation of the tire monitoring device and checks that the configuration data stored in the storage device has not been altered or has been correctly set. The transmission in box 718 can be sent directly to the control unit 12, to another tire monitoring device 10 for further routing, or to an access point or other wireless node.

[0071] use Figure 7 This method relies on the tire monitoring device itself to provide confirmation of tire pressure status. A malfunction in any sensor will cause all sensor readings to fail. In this way, the tire monitoring device can be certified using its own indicators according to the required DAL and / or SAL, without requiring the control unit to be certified as well.

[0072] In other examples, instead of transmitting a fault indication at box 710, all tire monitoring devices could transmit the pressure they measure to other tire monitoring devices. The received pressure could then be checked independently by each individual tire monitoring device to determine if a fault exists. This could prevent faults, such as the sensors not indicating low pressure conditions, for example, if the stored reference pressure has been corrupted.

[0073] In other examples, when it is determined in box 706 that the tire pressure is not low, the tire monitoring device can transmit a "normal" status notification. Such examples provide assurance that all sensors are operating correctly, as the absence of data from one of the other tire monitoring devices indicates that that device is malfunctioning or faulty.

[0074] While the above process describes using a general-purpose mobile device as a control device, the control device can also be a specialized device provided solely for use with a tire monitoring system or more generally with a vehicle. This can improve safety by enabling greater control.

[0075] While the above process describes the use of an indicator as light, other examples may use other indicators such as displays and / or audio components. For instance, instead of simply displaying a continuous or flashing color, a display could show information about the measured pressure itself. In cases where both audio and visual indicators are provided, some indicators may not use both simultaneously. For example, a "normal" indicator could use only a visual indicator, while the audio indicator is activated only in case of a malfunction.

[0076] Distance restrictions used to improve security

[0077] The use of wireless communication can increase security risks because wireless channels are more easily accessed by third parties. Encrypting messages exchanged between devices in a tire monitoring system makes it more difficult for malicious devices to eavesdrop or inject malicious commands or data without knowing the encryption key. As mentioned above, limiting the communication distance can also improve security. Such distance limitations can be inherent in wireless communication protocols; for example, NFC and RFID typically operate within a range of less than 30cm. Other wireless communication protocols, such as WiFi or 802.11, have a range of about 50m or less in unobstructed spaces when transmission power is limited. However, even when transmission power limits the communication range, it does not provide a clearly defined boundary. For example, the range can be extended by using directional antennas to improve sensitivity.

[0078] In this embodiment, a distance standard is used at the tire monitoring device. When communication occurs, the range or distance to the communicating device is determined and evaluated against the distance standard. If the range is greater than a threshold distance, communication is stopped, and no commands or data received are processed. Alternatively, commands or data received may be processed only if the range is below the threshold distance. Suitable threshold distances for general use of tire monitoring systems are 40m, 30m, or 25m. This physical proximity enhances security against malicious attacks.

[0079] Lower distance thresholds can be used for specific types of commands, such as configuration commands and / or the exchange of encryption keys. In this case, the distance threshold could be, for example, 1m, 50cm, 25cm, or 5cm.

[0080] Range can be determined using any suitable technique. Wireless communication protocols themselves may include ranging techniques. For example, ultra-wideband (UWB) communication incorporates range determination as part of its protocol stack. Preferably, for example, as defined in IEEE 802.15.4a or IEEE 802.15.4z, range or distance is actively determined by using time-of-flight measurements and exchanging range data between the transmitting and receiving devices.

[0081] The use of mandatory distance limits to improve the tire pressure check process will now be explained, for example, as shown in the reference. Figure 7 An example method for ensuring the safety of the described tire pressure check process. This method can be used to determine whether to execute or act on a command received via a wireless interface at box 702, or to determine whether data received from other sensors, such as fault messages, at box 712 should be processed or rejected.

[0082] Figure 8 An example method that can be used to implement distance limiting is depicted. First, at box 802, the tire monitoring device receives commands and / or data from another device in the tire monitoring system via a wireless interface. The commands and / or data can originate from the other tire monitoring device (e.g., for received data) or from a control device (e.g., for commands). In this example, data is received via a UWB wireless interface.

[0083] Next, at box 804, the range to the second device is determined. Any suitable ranging technique can be used. For example, a time-of-flight method in which the devices exchange ranging data, calculate the time of flight, and calculate the range provides an accurate distance measurement that is difficult to deceive.

[0084] Once the range is determined, at box 806, it is determined whether the range is below a predetermined distance threshold. If the range is below the threshold, execution proceeds to box 808, where commands are executed or data is processed as needed. If the range is above the threshold, the method terminates at box 810. In some examples, an alert may be provided, for example, by flashing an indicator or tire monitoring device, to indicate that a potentially malicious command or data has been received before the method terminates at 810.

[0085] It should be noted that, unless otherwise explicitly stated, the term “or” as used herein should be interpreted as “and / or”.

[0086] The examples above should be understood as illustrative examples of the invention. It should be understood that any feature described with respect to any example may be used alone or in combination with other described features, and may also be used in combination with one or more features of any other example or any combination of any other example. Furthermore, equivalents and modifications not described above may be employed without departing from the scope of the invention as defined by the appended claims.

Claims

1. A tire monitoring device for use in a tire monitoring system, the tire monitoring device being configured to be mounted on the wheels of an aircraft, and the tire monitoring device comprising: A wireless interface that has distance determination capability; as well as The processor is configured to: Receive commands via the wireless interface from the wireless transmission of the second device of the tire monitoring system; In response to receiving the command, the distance to the second device is determined; Wherein the distance to the second device is the length between the second device and the wireless interface, and The command is executed if the distance to the second device is less than a predetermined threshold.

2. A tire monitoring device for use in a tire monitoring system, the tire monitoring device being configured to be mounted on the wheels of an aircraft, and the tire monitoring device comprising: A wireless interface that has distance determination capability; as well as The processor is configured to: Data is received wirelessly from a second device of the tire monitoring system via the wireless interface; In response to receiving the data, the distance to the second device is determined; Wherein the distance to the second device is the length between the second device and the wireless interface, and If the distance to the second device is greater than a predetermined threshold, the data is rejected.

3. The tire monitoring device according to claim 2, wherein, The processor is configured to: Receive commands from a third device of the tire monitoring system via the wireless interface; Determine the distance to the third device; wherein the distance to the third device is the length between the third device and the wireless interface, and The command is executed when the distance to the third device is less than a predetermined threshold.

4. The tire monitoring device according to any one of claims 1 to 3, wherein, The wireless interface includes an ultra-wideband interface.

5. The tire monitoring device according to any one of claims 1 to 3, wherein, The predetermined threshold is less than or equal to 40 m.

6. A tire monitoring system comprising a plurality of tire monitoring devices according to any one of claims 1 to 5.

7. The tire monitoring system according to claim 6 further includes a control device, the control device including a wireless communication interface with distance determination capability.

8. A method for a wireless tire monitoring device, the tire monitoring device being mounted on the wheels of an aircraft and including a wireless interface, the method comprising: Commands are received wirelessly from the second device via the wireless interface; In response to receiving the command, the tire monitoring device determines the distance to the second device; Wherein the distance to the second device is the length between the second device and the wireless tire monitoring device, and If the distance to the second device is less than a predetermined threshold, the tire monitoring device executes the command.

9. A method for a wireless tire monitoring device, the tire monitoring device being mounted on the wheels of an aircraft and including a wireless interface, the method comprising: Data is received wirelessly from the second device via the wireless interface; In response to receiving the data, the tire monitoring device determines the distance to the second device; Wherein the distance to the second device is the length between the second device and the wireless interface, and If the distance to the second device is greater than a predetermined threshold, the tire monitoring device rejects the data.

10. The method of claim 9, further comprising: Receive commands from a third device of a tire monitoring system, including the tire monitoring device, via the wireless interface; In response to receiving the command, the tire monitoring device determines the distance to the third device; Wherein the distance to the third device is the length between the third device and the wireless interface, and The tire monitoring device executes the command if the distance to the third device is less than a predetermined threshold.

11. The method according to any one of claims 8 to 10, wherein, The wireless interface includes an ultra-wideband interface.

12. The method according to any one of claims 8 to 10, wherein, The predetermined threshold is less than or equal to 40 m.

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