Wheel monitoring system

Abstract

To provide a wheel monitoring system that can detect theft of wheel, tire change or the like while suppressing electrical power consumption due to transmission of information by a tire sensor.SOLUTION: A wheel monitoring system includes a tire sensor 2. The tire sensor 2 determines that wheels 10a-10d are stollen when an acceleration sensor 22 detects a predetermined acceleration change while a vehicle 10 is in a parking state. The tire sensor 2 determines that there is a possibility that tire rotation or change has been carried out when the acceleration sensor 22 detects a predetermined acceleration change while the vehicle 10 is in a stopping state.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004]

[0001] The present disclosure relates to a wheel monitoring system.

Background Art

[0002] Conventionally, there is known a vehicle theft reporting system that transmits warning information to the outside of the vehicle based on, for example, that the change amount of the acceleration applied to a tire exceeds a first acceleration range when the main power source of the vehicle is turned off and the vehicle door is locked (see, for example, Patent Document 1).

[0003] The system described in this Patent Document 1 detects the air pressure etc. of each tire with a tire sensor (that is, a TPMS transmitter) attached to each tire. Then, an in-vehicle device mounted on the vehicle body of the vehicle periodically acquires tire information including the air pressure of the tire from the tire sensor, and determines whether or not the change amount of the acceleration applied to the tire exceeds the first acceleration range.

Prior Art Documents

Patent Documents

[0004] <00000,19>[[ID=,26]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, the present inventors have been considering monitoring the acceleration applied to a tire to detect wheel theft. However, when monitoring the acceleration applied to a tire with an in-vehicle device as in the prior art, the tire sensor needs to frequently transmit tire information, and the tire sensor consumes a lot of power due to the information transmission. This is the same not only when detecting wheel theft but also when detecting tire replacement etc.

[0006] This disclosure aims to provide a wheel monitoring system capable of detecting wheel theft, tire replacement, etc., while suppressing power consumption caused by information transmission from tire sensors. [Means for solving the problem]

[0007] The invention described in claim 1 is, A wheel monitoring system applicable to a vehicle (10) in which a vehicle body (11) is fitted with multiple wheels (10a to 10d) including tires, A tire sensor (2) is provided on the wheel and includes an acceleration sensor (22) that outputs acceleration that changes with the rotation of the wheel, The vehicle is equipped with an on-board unit (3) installed on the vehicle body, The tire sensor and in-vehicle unit are configured to communicate bidirectionally. The in-vehicle unit determines whether the vehicle is parked, stopped, or in motion based on the vehicle's speed, the status of the vehicle's doors, and the on / off status of the vehicle's ignition switch, and transmits information including the determination result to the tire sensor. The tire sensor identifies the current vehicle status based on information received from the in-vehicle device, and based on the combination of the identified vehicle status and the sensor output of the speed sensor, wheel theft It will be determined whether the action was taken. tire rotation or Tire replacement Is it possible that this was done? Determine.

[0008] Thus, with a configuration in which the vehicle status determination result from the in-vehicle unit is notified to the tire sensor 2 (vehicle status synchronization), it is sufficient for the tire sensor to receive information from the in-vehicle unit only once each time the vehicle status changes, thus significantly reducing the power consumption of the tire sensor. Therefore, it becomes possible to detect wheel theft, tire replacement, etc., while suppressing power consumption caused by information transmission from the tire sensor.

[0009] In the invention described in claim 3, the tire sensor determines that a wheel has been stolen when a predetermined change in acceleration is detected by the acceleration sensor while the vehicle is parked.

[0010] By performing wheel theft detection on the tire sensor side in this way, there is no need to increase the frequency of information transmission from the tire sensor. Therefore, it becomes possible to detect wheel theft while suppressing power consumption caused by information transmission from the tire sensor.

[0011] In the invention described in claim 4, when the vehicle is stationary, the tire sensor determines that a predetermined change in acceleration is detected by the acceleration sensor, and that there is a possibility that the tires have been rotated or replaced.

[0012] Thus, if the tire sensor itself makes the determination of tire replacement or other related matters based on the detection results of the acceleration sensor, it is possible to detect tire replacement or other related matters without increasing the frequency of information transmission from the tire sensor. Therefore, it becomes possible to detect tire replacement or other related matters while suppressing power consumption caused by information transmission from the tire sensor.

[0013] The reference numerals in parentheses attached to each component indicate an example of the correspondence between that component and the specific components described in the embodiments described later. [Brief explanation of the drawing]

[0014] [Figure 1] This is an overall configuration diagram of the wheel monitoring system according to the embodiment. [Figure 2] This is a block diagram of the tire sensor. [Figure 3] This is a block diagram of the in-vehicle unit. [Figure 4] This flowchart shows the flow of control processing performed by the tire sensor. [Figure 5] This flowchart shows the flow of the theft detection process performed by the tire sensor. [Figure 6] This is an explanatory diagram to describe the condition of the vehicle. [Figure 7] This flowchart shows the flow of the anti-theft alarm process performed by the tire sensor. [Figure 8] It is a flowchart showing the flow of theft alarm processing executed by the in-vehicle device of the bicycle. [Figure 9] It is a flowchart showing the flow of theft tracking processing executed by the tire sensor. [Figure 10] It is an explanatory diagram for explaining the theft master code. [Figure 11] It is a flowchart showing the flow of theft tracking processing executed by the in-vehicle device of another vehicle. [Figure 12] It is a flowchart showing the flow of detection processing such as tire replacement executed by the tire sensor. [Figure 13] It is a flowchart showing the flow of corresponding processing such as tire replacement executed by the in-vehicle device. [Figure 14] It is an explanatory diagram for explaining the relationship between the door state, vehicle speed, vehicle state, two-way communication, acceleration change, and determination.

Mode for Carrying Out the Invention

[0015] An embodiment of the present disclosure will be described based on FIGS. 1 to 14. FIG. 1 is a diagram showing a wheel monitoring system. The front-rear and left-right shown in FIG. 1 indicate the front-rear and left-right in the vehicle 10. Also, hereinafter, when distinguishing and explaining the four wheels 10a to 10d attached to the vehicle 10, the four wheels 10a to 10d may be denoted as the left front wheel FL, the right front wheel FR, the left rear wheel RL, and the right rear wheel RR.

[0016] The wheel monitoring system has a function of detecting wheel theft and a function of detecting the presence or absence of tire replacement. That is, the wheel monitoring system functions as a wheel theft detection system and also functions as a tire replacement detection system. As shown in FIG. 1, the wheel monitoring system uses a plurality of tire sensors 2, an in-vehicle device 3, a brake ECU 4, a meter 5, a door lock ECU 6, and a mobile communication device 7 to detect the theft of the wheels 10a to 10d.

[0017] Each tire sensor 2 and the on-board unit 3 are components of the tire pressure monitoring system (hereinafter referred to as TPMS). The TPMS uses each tire sensor 2 and the on-board unit 3, as well as information from the brake ECU 4, to perform auto-location, which automatically detects the wheel position.

[0018] The brake ECU 4 is an electronic control unit for brake control. The brake ECU 4 acquires wheel speed pulses obtained from the detection signals of wheel angle sensors 4a to 4d, which are provided for each wheel 10a to 10d, and transmits this information to the on-board unit 3 for wheel position detection.

[0019] The wheel angle sensors 4a to 4d are generally called wheel speed sensors. These sensors output a signal corresponding to the tooth position of the gear that rotates with the axle as a wheel speed pulse, but here they are used to obtain the angle at which the tire sensor 2 is located relative to the central axis of each wheel 10a to 10d, and are therefore called "wheel angle sensors".

[0020] The tire sensor 2 is attached to each wheel 10a to 10d and detects the air pressure of the tires attached to the wheels 10a to 10d, and stores the detected tire pressure information in a frame and transmits it. The on-board unit 3 is attached to the vehicle body 11 side of the vehicle 10 and receives the frame transmitted from the tire sensor 2 and performs various processing and calculations based on the information stored therein to detect the tire pressure.

[0021] As shown in Figure 2, the tire sensor 2 comprises an air pressure detection unit 21, an acceleration sensor 22, a first microcomputer 23, and a tire radio 24, and each part is driven based on power supplied from a battery (not shown).

[0022] The air pressure detection unit 21 is equipped with a pressure sensor 21a and a temperature sensor 21b, and outputs detection signals corresponding to tire pressure and temperature. The acceleration sensor 22 is used to detect the rotation angle of the tire sensor 2, the driving speed (i.e., vehicle speed) of the vehicle 10, and theft detection. The acceleration sensor 22 is composed of, for example, a two-axis acceleration sensor capable of detecting radial acceleration and circumferential acceleration of each wheel 10a to 10d.

[0023] The first microcomputer 23 constitutes the control unit for the tire sensor 2 and is equipped with a CPU, memory such as ROM and RAM, I / O, etc. The first microcomputer 23 executes predetermined processing according to a program stored in its internal memory. The memory stores individual ID information, including a unique tire ID for identifying each tire sensor 2 and a vehicle-specific vehicle ID for identifying the vehicle itself.

[0024] The first microcomputer 23 receives, for example, detection signals from the pressure sensor 21a and the temperature sensor 21b, processes them, and modifies them as necessary, and stores the tire pressure information along with the ID information of each tire sensor 2 within the frame.

[0025] Furthermore, the first microcomputer 23 monitors the detection signals from the acceleration sensor 22 and performs a vehicle driving determination, which determines the angle of each tire sensor 2 and whether or not the vehicle 10 is in motion. After creating a frame, the first microcomputer 23 transmits the frame from the tire radio 24 to the on-board unit 3 based on the results of the vehicle driving determination. Hereafter, information regarding tire pressure will also be simply referred to as tire information.

[0026] Specifically, the first microcomputer 23 repeatedly transmits frames at predetermined intervals while the vehicle 10 is in motion. The first microcomputer 23 determines whether or not the vehicle 10 is in motion based on the detection results of the acceleration sensor 22. The first microcomputer 23 determines that the vehicle 10 is in motion when the acceleration detected by the acceleration sensor 22 exceeds a certain value. This certain value is, for example, a value corresponding to the centrifugal acceleration that occurs when traveling at approximately 5 km / h.

[0027] Furthermore, since the acceleration sensor 22 outputs a detection signal corresponding to the rotation of each wheel 10a to 10d, during driving, the detection signal includes a gravitational acceleration component, resulting in a signal with an amplitude corresponding to the wheel rotation. Therefore, the position of the acceleration sensor 22, i.e., the rotation angle of the tire sensor 2, can be determined based on this amplitude.

[0028] The tire radio 24 includes a first transceiver circuit 241 and a first communication antenna 242. The first transceiver circuit 241 is a communication circuit that communicates bidirectionally with the in-vehicle unit 3 through the first communication antenna 242. The first transceiver circuit 241 performs wireless communication based on a communication method such as BLE. BLE is an abbreviation for Bluetooth® Low Energy. The first transceiver circuit 241 may also perform wireless communication based on a communication method other than BLE.

[0029] The first communication antenna 242 is an antenna for bidirectional communication with the in-vehicle unit 3. The tire sensor 2 is equipped with a tire radio 24, enabling not only unidirectional communication from the tire sensor 2 to the in-vehicle unit 3, but also bidirectional communication with the in-vehicle unit 3.

[0030] Specifically, the tire sensor 2 communicates wirelessly with the in-vehicle unit 3 based on BLE. Wireless communication based on BLE allows for both bidirectional unicast communication and unidirectional broadcast communication.

[0031] Unicast communication is a communication method in which a virtual connection (a virtual dedicated communication channel) is established with the other party before communication begins, and data is sent and received through the established connection. The tire sensor 2 is able to send and receive data with the vehicle's onboard unit 3 using unicast communication.

[0032] On the other hand, broadcast communication, also known as connectionless communication, is a communication method that unilaterally transmits data without checking the status of the other party before initiating communication. The tire sensor 2 can transmit and receive data not only with its own vehicle's onboard unit 3, but also with onboard units 3 of other vehicles in the vicinity of the tire sensor 2 using broadcast communication.

[0033] The tire sensor 2 configured in this way detects tire pressure and tire temperature, and transmits a frame when the angle of the tire sensor 2 reaches a predetermined angle while the vehicle 10 is in motion.

[0034] In addition, the tire sensor 2 detects the theft of wheels 10a to 10d based on the acceleration that changes with the rotation of wheels 10a to 10d when the vehicle 10 is stopped and its speed is below a predetermined speed (for example, 5 km / h). The hardware and software of the tire sensor 2 that perform the theft detection of wheels 10a to 10d constitute a "tire monitoring unit 23a" for determining whether or not wheels 10a to 10d have been stolen.

[0035] On the other hand, the on-board unit 3 is installed in the vehicle body 11. As shown in Figure 3, the on-board unit 3 is equipped with an on-board radio 31 and a second microcomputer 33, etc. The on-board unit 3 acquires the tooth position, indicated by the number of edges or teeth, of the gears that rotate with each wheel 10a to 10d by acquiring wheel speed pulses from the brake ECU 4 as described later via an in-vehicle LAN (Local Area Network) such as CAN (Controller Area Network). In the following explanation, the number of edges will be used as an example to explain the gear information, but the number of teeth can also be used. The on-board unit 3 also acquires the detected value of a steering angle sensor (not shown) (i.e., the steering angle of the steering wheel) via the in-vehicle LAN.

[0036] The on-board radio 31 includes a second communication antenna 311 and a second transmitting / receiving circuit 312. The second communication antenna 311 is an antenna for bidirectional communication with each tire sensor 2. In addition to receiving frames and other data sent from each tire sensor 2, the second communication antenna 311 is also used to transmit signals to each tire sensor 2. The second communication antenna 311 may be an internal antenna located inside the main body of the on-board unit 3, or it may be an external antenna with wiring extended from the main body.

[0037] The second transceiver circuit 312 is a communication circuit that communicates bidirectionally with each tire sensor 2 via the second communication antenna 311. The second transceiver circuit 312 performs wireless communication based on a communication method such as BLE. The second transceiver circuit 312 functions as an input unit that receives transmission frames from each tire sensor 2 received by the second communication antenna 311 and sends those frames to the second microcomputer 33. When the second transceiver circuit 312 receives a frame via the second communication antenna 311, it transmits the received signal to the second microcomputer 33.

[0038] The second microcomputer 33 constitutes the control unit of the in-vehicle unit 3 and is equipped with a CPU, memory such as ROM and RAM, I / O, etc. The second microcomputer 33 performs wheel position detection processing and tire air pressure detection processing according to the program stored in its internal memory.

[0039] In the wheel position detection process, wheel position detection is performed to determine which of the wheels 10a to 10d the tire sensor 2 is attached to. Specifically, the second microcomputer 33 performs wheel position detection based on information obtained from the brake ECU 4 and information obtained from each tire sensor 2. The second microcomputer 33 obtains wheel speed pulses, which are output signals from wheel angle sensors 4a to 4d, each of which is provided for each wheel 10a to 10d, from the brake ECU 4 at a predetermined period, for example, every 10ms.

[0040] The wheel speed pulse is information indicating the tooth position of the gears that rotate with each wheel 10a to 10d. The wheel angle sensors 4a to 4d are composed of, for example, electromagnetic pickup type sensors positioned opposite the gear teeth, and change the detection signal as the gear teeth pass by. In this type of wheel angle sensor 4a to 4d, a square pulse wave corresponding to the passage of the teeth is output as the detection signal, so the rising and falling edges of the square pulse wave represent the passage of the gear tooth edges. The brake ECU 4 counts the number of gear tooth edges, i.e., the number of edges passed, as wheel speed pulses from the number of rising and falling edges of the detection signals of the wheel angle sensors 4a to 4d. For example, if the number of teeth on the gear is 48, the number of edges counted is 0 to 95, totaling 96, when the gear rotates once. Then, at predetermined intervals, the brake ECU 4 transmits the number of tooth edges at that time as a wheel speed pulse to the second microcomputer 33.

[0041] The second microcomputer 33 acquires wheel speed pulses from wheel angle sensors 4a to 4d and converts the change in the acquired wheel speed pulses into the rotation angle of each wheel 10a to 10d. If the total number of wheel speed pulses when wheels 10a to 10d complete one rotation is 96, then the rotation angle of wheels 10a to 10d per wheel speed pulse is 3.75°. Therefore, by multiplying the change in the wheel speed pulses by 3.75°, the change in the wheel speed pulses can be converted into the rotation angle of each wheel 10a to 10d.

[0042] The second microcomputer 33 compares the rotation angles of the wheels 10a to 10d based on the wheel angle sensors 4a to 4d with the rotation angles of the tire sensors 2 based on the tire sensors 2, and associates those whose rotation angles fall within a predetermined range. This makes it possible to perform wheel position detection to identify which wheel 10a to 10d each tire sensor 2 is attached to.

[0043] The tire pressure detection process detects the tire pressure of wheels 10a to 10d to which each tire sensor 2 is attached. Specifically, the second microcomputer 33 associates and stores the ID information of each tire sensor 2 with the position of each wheel 10a to 10d to which each tire sensor 2 is attached, based on the results of wheel position detection. Subsequently, it detects the tire pressure of each wheel 10a to 10d by calculating the equivalent tire pressure value at a predetermined temperature based on the ID information and tire information stored in the transmission frame from each tire sensor 2. Then, it outputs an electrical signal corresponding to the tire pressure detection result to the meter 5 via the in-vehicle LAN such as CAN. For example, the second microcomputer 33 outputs a signal indicating the tire pressure of each wheel 10a to 10d to the meter 5. In addition, the second microcomputer 33 detects a decrease in tire pressure by comparing the tire pressure with a predetermined judgment threshold, and outputs a signal to that effect to the meter 5 when a decrease in tire pressure is detected. This allows the meter 5 to be notified if the tire pressure of any of the four wheels 10a to 10d has decreased, and this is then displayed on the meter 5.

[0044] Meter 5 is a display unit located inside the vehicle cabin that displays various information. Meter 5 is powered on when the power is turned on, specifically when the accessory (ACC) switch or ignition switch (IG) or other starting switch is turned on, and displays various information when the power is on. The display by Meter 5 is basically performed when the power is on.

[0045] The meter 5 is positioned in a location visible to the driver and consists of, for example, a multi-information display or navigation system display installed in the instrument panel of the vehicle 10. When the meter 5 receives a signal from, for example, the second microcomputer 33 in the in-vehicle unit 3 indicating that the tire pressure has decreased, it identifies the relevant wheel and displays a message indicating the decrease in tire pressure to inform the driver of the decrease in the tire pressure of that wheel.

[0046] The door lock ECU 6 is a control device that controls the locking and unlocking of the doors of the vehicle 10. When the doors are locked, it outputs a door lock signal to the on-board unit 3. When the doors are unlocked, it outputs a door unlock signal to the on-board unit 3. This door lock ECU 6 is always in operation, both when the ignition switch IG is on, when the ignition switch IG is off and the doors are locked, and when the doors are locked after the ignition switch IG is off.

[0047] The mobile communication device 7 is a wireless communication unit for communicating with external communication destinations of the vehicle 10. When the ignition switch IG is turned on, the mobile communication device 7 becomes active and communicates with a service center 73 connected to the communication network 72 by wirelessly connecting with a wireless base station 71 connected to the communication network 72 (mobile communication network, internet, etc.).

[0048] The service center 73 communicates with the user terminal 75 (a terminal carried by the user of the vehicle 10) via the communication network 72 and the base station 74. The service center 73 also communicates with a security system (not shown) via the communication network 72. The security system is a communication device owned and operated by a security company or the police.

[0049] Next, various control processes, including theft detection of wheels 10a to 10d, performed by each tire sensor 2 and the on-board unit 3, will be explained in detail with reference to Figures 4 to 12. The control processes shown in Figure 4 are performed periodically or irregularly by each tire sensor 2.

[0050] As shown in Figure 4, the tire sensor 2 performs theft detection processing in step S100. This theft detection processing determines whether the theft of wheels 10a to 10d has been detected. Details of the theft detection processing will be explained with reference to Figure 5.

[0051] As shown in Figure 5, the tire sensor 2 reads various information in step S101. Specifically, the tire sensor 2 reads information about changes in acceleration from the acceleration sensor 22. The tire sensor 2 also reads information such as the on / off status of the ignition switch IG, and door information including the door lock and unlock status, via the in-vehicle unit 3.

[0052] In step S102, the tire sensor 2 determines whether or not the vehicle 10 is in a stopped state. In this specification, as shown in Figure 6, the "stopped state" of the vehicle 10 is defined as a state in which the vehicle's travel speed (i.e., vehicle speed) is less than 5 km / h, such as the "parked state" and the "stopped state".

[0053] Here, "parked state" is the state in which the vehicle speed is less than 5 km / h, the doors are locked, and the ignition switch IG is off. "Stopped state" is the state in which the vehicle speed is less than 5 km / h, the ignition switch IG is on, or the doors are unlocked. "Driving state" is the state in which the ignition switch IG is on and the vehicle speed is 5 km / h or more. The states of vehicle 10, such as "parked state," "stopped state," and "driving state," can be determined based on the vehicle's driving speed, the state of the doors, and whether the ignition switch IG is on or off.

[0054] If vehicle 10 is in motion and not stationary, there is no possibility of theft, so tire sensor 2 skips the subsequent processing and exits this process. On the other hand, if vehicle 10 is not stationary, tire sensor 2 determines in step S103 whether the doors are locked and the ignition switch IG is turned off. In other words, tire sensor 2 determines whether the state of vehicle 10 is "parked". Note that when stationary, if the doors are locked and the ignition switch IG is turned off, vehicle 10 is in "parked" state.

[0055] As a result of this determination process, if the doors of vehicle 10 are in the unlocked state or the ignition switch IG is on (i.e., the state of vehicle 10 is "stationary"), the tire sensor 2 skips the subsequent processing and exits this process. On the other hand, if the doors of vehicle 10 are in the locked state and the ignition switch IG is off (i.e., the state of vehicle 10 is "parked"), the tire sensor 2 proceeds to step S104. In step S104, the tire sensor 2 determines whether a predetermined acceleration change has been detected by the acceleration sensor 22. The predetermined acceleration change is set to, for example, the range of fluctuation of the detected value of the acceleration sensor 22 that occurs when a tire is changed.

[0056] If the result of step S104 is a positive judgment (YES), it means that a predetermined change in acceleration was detected by the acceleration sensor 22 while the vehicle 10 was stationary, with the doors locked and the ignition switch IG off (i.e., parked). When changing tires, the doors are often unlocked or the ignition switch IG is turned on for convenience during the work. On the other hand, the theft of wheels 10a to 10d almost always occurs while the vehicle 10 is stationary, with the doors locked and the ignition switch IG off (i.e., parked). Therefore, if a predetermined change in acceleration is detected by the acceleration sensor 22 while the vehicle 10 is stationary, with the doors locked and the ignition switch IG off (i.e., parked), there is a high probability that wheels 10a to 10d have been stolen. Therefore, when the vehicle 10 is stopped, with the doors locked and the ignition switch IG off (i.e., parked), if a predetermined change in acceleration is detected by the acceleration sensor 22, the tire sensor 2 turns on the first theft flag in step S105. This first theft flag is turned on when wheels 10a to 10d are stolen. Since the first theft flag is turned on when a predetermined change in acceleration is detected by the acceleration sensor 22, it is presumed that wheels 10a to 10d are present around the vehicle 10.

[0057] On the other hand, if the result of step S104 is a negative determination (NO), that is, if the acceleration sensor 22 does not detect a predetermined acceleration change, the tire sensor 2 checks in step S106 whether it is possible to communicate with the in-vehicle unit 3. Then, in step S107, the tire sensor 2 determines whether communication with the in-vehicle unit 3 has been interrupted. This communication check, for example, confirms whether it is possible to establish a connection for unicast communication with the in-vehicle unit 3.

[0058] If communication is possible with the on-board unit 3, it is assumed that the wheels 10a to 10d are attached to the vehicle 10. Therefore, if communication is possible with the on-board unit 3, the tire sensor 2 skips the subsequent processing and exits this process.

[0059] On the other hand, if communication with the on-board unit 3 is lost, it is assumed that the wheels 10a to 10d, to which each tire sensor 2 is attached, have been stolen and taken to a location far away from the on-board unit 3 attached to the vehicle body 11. Therefore, if communication with the on-board unit 3 is lost, the tire sensor 2 turns on the second theft flag in step S108. The second theft flag, like the first theft flag, is a flag that is turned on when the wheels 10a to 10d are stolen. Since the second theft flag is turned on when communication between the tire sensor 2 and the on-board unit 3 is lost, it is presumed that the wheels 10a to 10d are located far away from the vehicle 10.

[0060] This concludes the explanation of the theft detection process. Once the theft detection process in step S100 in Figure 4 is completed, the tire sensor 2 proceeds to step S110 and determines whether the first theft flag is on or off.

[0061] If the first theft flag is on, the tire sensor 2 performs theft alarm processing in step S120, and then exits this process. This theft alarm processing will be explained with reference to Figures 7 and 8.

[0062] As shown in Figure 7, in step S121A, the tire sensor 2 transmits a theft signal to the vehicle's onboard unit 3 via unicast communication. This theft signal indicates that the vehicle's wheels 10a to 10d have been stolen, and for security reasons, it is designed to be receivable only by the vehicle's onboard unit 3.

[0063] As shown in Figure 8, in step S121B, the vehicle's onboard unit 3 determines whether or not it has received a theft signal from the tire sensors 2 attached to the vehicle's wheels 10a to 10d. If it receives a theft signal from the tire sensors 2, the vehicle's onboard unit 3 proceeds to step S122B, where it sends a response signal to the tire sensors 2, the source of the theft signal, and also uses the vehicle's onboard notification unit to notify the theft of wheels 10a to 10d. For example, the vehicle's onboard unit 3 may emit an alarm sound from an onboard alarm device (not shown) or activate the hazard lights to notify people near the vehicle 10 of the theft of wheels 10a to 10d. In this example, the onboard alarm device and hazard lights constitute the "notification unit". If the ignition switch IG is ON, the vehicle's onboard unit 3 may, for example, use a mobile communication device 7 to notify a service center 73 of the theft.

[0064] After transmitting the theft signal, the tire sensor 2 determines in step S122A whether or not it has received a response signal from the vehicle's onboard unit 3. If it has received a response signal from the vehicle's onboard unit 3, it means that communication with the vehicle's onboard unit 3 has been established. Therefore, if the tire sensor 2 has received a response signal from the vehicle's onboard unit 3, it exits this process.

[0065] On the other hand, if no response signal is received from the vehicle's onboard unit 3, it means that communication with the vehicle's onboard unit 3 has been lost. Therefore, if no response signal is received from the vehicle's onboard unit 3, the tire sensor 2 proceeds to the theft tracking process in step S140 of Figure 4 in step S123A.

[0066] Returning to Figure 4, if the determination process in step S110 determines that the first theft flag is off, the tire sensor 2 determines in step S130 whether or not the second theft flag is on.

[0067] If the second theft flag is turned on, the tire sensor 2 performs the theft tracking process in step S140, and then exits this process. This theft tracking process will be explained with reference to Figures 9, 10, and 11.

[0068] As shown in Figure 9, in step S141A, the tire sensor 2 transmits a theft master code via broadcast communication to an in-vehicle unit 3 installed in another vehicle, and exits this process. This theft master code is a data code that includes information about the vehicle's tires. For example, as shown in Figure 10, the theft master code includes data such as the theft master ID, ID information to identify the tire sensor 2, the wheel position to which the tire sensor 2 is attached, tire pressure, and the remaining battery level of the tire sensor 2.

[0069] In response, the onboard unit 3 of the other vehicle performs the theft tracking process shown in Figure 11 so that it can receive the theft master code. The theft tracking process shown in Figure 11 is performed periodically or irregularly by the onboard unit 3 of the other vehicle.

[0070] As shown in Figure 11, in step S141B, the in-vehicle unit 3 of the other vehicle determines whether or not it has received the theft master code. If it has received the theft master code, in step S142B, the other vehicle's in-vehicle unit 3 notifies the service center 73 outside the vehicle 10 of the tire theft information. The tire theft information includes the vehicle's tire information, excluding the theft master ID, as well as the location and time (e.g., timestamp) when the theft master code was received.

[0071] The service center 73 identifies the users of wheels 10a to 10d based on the tire theft information and notifies the user terminals 75 of those users that wheels 10a to 10d have been stolen. The service center 73 may also be configured to notify the security company or police via the security system that wheels 10a to 10d have been stolen.

[0072] Returning to Figure 4, if the determination process in step S130 determines that the second theft flag is off, the tire sensor 2 executes the tire change / rotation detection process in step S150. This detection process will be explained with reference to Figure 12.

[0073] As shown in Figure 12, the tire sensor 2 reads various information in step S151. Specifically, the tire sensor 2 reads information regarding changes in acceleration from the acceleration sensor 22. The tire sensor 2 also reads information such as the on / off status of the ignition switch IG, and door information including the door lock and unlock states, via the in-vehicle unit 3.

[0074] In step S152, the tire sensor 2 determines whether or not the vehicle 10 is stopped. This determination process is the same as the determination process in step S102 in Figure 5, so its explanation is omitted.

[0075] If vehicle 10 is in motion and not stationary, tire sensor 2 skips the subsequent processing and exits this process. On the other hand, if vehicle 10 is not stationary, tire sensor 2 determines in step S153 whether the doors are locked or whether the ignition switch IG is turned on.

[0076] If, as a result of this determination process, the doors of vehicle 10 are locked and the ignition switch IG is off (i.e., the vehicle is in a "parked state"), the tire sensor 2 skips the subsequent processing and exits this process. On the other hand, if the doors of vehicle 10 are unlocked or the ignition switch IG is off (i.e., the vehicle is in a "stopped state"), the tire sensor 2 proceeds to step S154. In step S154, the tire sensor 2 determines whether a predetermined acceleration change has been detected by the acceleration sensor 22. The predetermined acceleration change is set, for example, to the range of fluctuation of the detected value of the acceleration sensor 22 that occurs when a tire is changed.

[0077] If the result of step S154 is a positive determination (YES), it means that a predetermined change in acceleration was detected by the acceleration sensor 22 while the vehicle 10 was stopped, with the doors unlocked or the ignition switch IG turned on (i.e., stationary). In this case, it is highly likely that a tire change or tire rotation has been performed. Therefore, in step S155, the tire sensor 2 turns on the tire change flag, indicating that a tire change or rotation may have been performed, and notifies the in-vehicle unit 3 of this information before exiting this process.

[0078] When the in-vehicle unit 3 detects that the tire change flag is turned on, it executes the necessary processing, such as changing the tires. The following describes the processing, such as changing the tires, that the in-vehicle unit 3 executes, with reference to Figure 13.

[0079] As shown in Figure 13, in step S200, the onboard unit 3 determines whether the vehicle 10 is in a driving state or not. Specifically, for example, the onboard unit 3 determines that the vehicle 10 is in a driving state if the vehicle speed is 5 km / h or more, and determines that the vehicle 10 is stopped if the vehicle speed is less than 5 km / h.

[0080] When the vehicle 10 is in motion, the on-board unit 3 determines in step S210 whether or not the rotation of all wheels 10a to 10d, which are pre-registered in the on-board unit 3, has been detected. This determination process can be performed, for example, by comparing the ID information obtained from each tire sensor 2 with the pre-registered ID information and detecting the rotation of the wheels 10a to 10d based on the acceleration information obtained from each tire sensor 2.

[0081] If none of the pre-registered wheels 10a to 10d are detected, it is assumed that a tire change has been performed. Therefore, if none of the pre-registered wheels 10a to 10d are detected, the in-vehicle unit 3 performs an automatic ID registration process in step S220, which automatically registers the tire ID, indicating that a tire change has been performed.

[0082] On the other hand, if all pre-registered wheels 10a to 10d are detected, it is assumed that no tire change has been performed, but it is possible that tire rotation has been carried out. Therefore, in step S230, the tire sensor 2 performs auto-location to automatically detect the positions of the wheels 10a to 10b to which the tire sensor 2 is attached, assuming that no tire change has been performed.

[0083] The wheel monitoring system described above uses tire sensor 2 to determine if wheels 10a to 10d have been stolen. Specifically, when the vehicle 10 is parked, if a predetermined change in acceleration is detected by acceleration sensor 22, tire sensor 2 determines that wheels 10a to 10d have been stolen. In this way, by configuring tire sensor 2 to perform the theft determination of wheels 10a to 10d based on the detection results of acceleration sensor 22, the theft of wheels 10a to 10d can be detected without increasing the frequency of information transmission by tire sensor 2. Therefore, the theft of wheels 10a to 10d can be detected while suppressing power consumption caused by information transmission by tire sensor 2.

[0084] Furthermore, the wheel monitoring system offers the following benefits:

[0085] (1) The tire sensor 2 includes a tire radio 24 that can communicate bidirectionally with the in-vehicle unit 3. When the tire monitoring unit 23a detects the theft of wheels 10a to 10d, it transmits a theft signal to the in-vehicle unit 3 via the tire radio 24, indicating that wheels 10a to 10d have been stolen. When the in-vehicle unit 3 receives the theft signal from the tire sensor 2, it uses an alert unit installed in the vehicle 10 to notify the vehicle of the theft of wheels 10a to 10d. In this way, if the vehicle 10 notifies the vehicle of the theft of wheels 10a to 10d when the theft is detected, it becomes easier for the user to quickly take action regarding the theft of wheels 10a to 10d (for example, by notifying the police, security company, etc.).

[0086] (2) When the in-vehicle unit 3 receives a theft signal, it transmits a response signal to the tire sensor 2. If the tire sensor 2 does not receive a response signal from the in-vehicle unit 3 after transmitting the theft signal, it transmits a theft master code containing the vehicle's tire information to an in-vehicle unit 3 installed in another vehicle. When the in-vehicle unit 3 installed in the other vehicle receives the theft master code, it notifies the service center 73 outside the vehicle 10 of the tire theft information, including the location and time the theft master code was received, in addition to the tire information. As a result, even after the vehicle's wheels 10a to 10d have been stolen, the stolen tires can be tracked based on the tire theft information notified to the service center 73. This is an effective theft prevention measure for wheels 10a to 10d.

[0087] (3) Specifically, as shown in Figure 14, when the vehicle 10 is parked, the tire sensor 2 determines that wheels 10a to 10d have been stolen if a change in acceleration is detected by the acceleration sensor 22. Also, when the vehicle 10 is stationary, if a change in acceleration is detected by the acceleration sensor 22, it determines that there is a possibility that the tires have been rotated or replaced. This makes it possible to distinguish between wheel theft and intentionally moving wheels 10a to 10d, such as through tire rotation or replacement, thereby improving the accuracy of detecting wheel theft.

[0088] (4) In addition, the tire monitoring unit 23a of the tire sensor 2 determines that the wheels 10a to 10d have been stolen if communication with the on-board unit 3 is lost when the vehicle 10 is parked.

[0089] If the wheels 10a to 10d are stolen and taken away from the vehicle body 11 of the vehicle 10, communication between the tire sensor 2 and the on-board unit 3 is interrupted. Therefore, the tire sensor 2 can determine whether the wheels 10a to 10d have been stolen based on the success or failure of communication between the on-board unit 3 and the tire sensor 2. In this type of theft detection for wheels 10a to 10d, it is not necessary to increase the frequency of information transmission by the tire sensor 2. Thus, it is possible to detect the theft of wheels 10a to 10d while suppressing power consumption caused by information transmission by the tire sensor 2.

[0090] (5) When the tire monitoring unit 23a detects the theft of wheels 10a to 10d, the tire sensor 2 transmits a theft master code, which includes the vehicle's tire information, to an on-board unit 3 installed in another vehicle. When the on-board unit 3 in the other vehicle receives the theft master code, it notifies the service center 73 outside the vehicle 10 of the tire theft information, which includes the location and time the theft master code was received, in addition to the tire information. As a result, even after the vehicle's wheels 10a to 10d have been taken away by theft, the stolen wheels 10a to 10d can be tracked based on the tire theft information notified to the service center 73. This is an effective measure to prevent the theft of wheels 10a to 10d.

[0091] (6) The in-vehicle unit 3 determines that a tire change has been performed if, while the vehicle 10 is in motion, rotation is not detected in any of the pre-registered wheels 10a to 10d. Conversely, while the vehicle 10 is in motion, if rotation is detected in all of the pre-registered wheels 10a to 10d, it determines that a tire change has not been performed. This allows for appropriate detection of tire changes. This also allows for appropriate timing of actions such as automatic ID registration of the tire sensor 2.

[0092] (modified version) In the above-described embodiment, the tire sensor 2 reads various information from the in-vehicle unit 3, including the vehicle's speed, door status, and the on / off status of the ignition switch IG, when performing theft detection processing or tire change / rotation detection processing. Based on the various information read from the in-vehicle unit 3, the tire sensor 2 determines whether the vehicle 10 is in a "parked state," a "stopped state," or a "driving state," and then performs theft detection processing, tire change detection processing, etc.

[0093] In such cases, the tire sensor 2 needs to frequently receive information from the in-vehicle unit 3, and this information reception may cause the tire sensor 2 to consume a lot of power. In addition, an increase in various judgment processes on the tire sensor 2 side will also be a factor that increases the power consumption of the tire sensor 2.

[0094] Here, for the theft detection process and the tire change / rotation detection process, it is sufficient to determine whether vehicle 10 is in a "parked state," a "stopped state," or a "driving state." Note that "parked state" is, for example, when vehicle 10 is stopped, the doors are locked, and the ignition switch is off. "Stopped state" is when vehicle 10 is stopped, the doors are unlocked, or the ignition switch is off.

[0095] On the in-vehicle unit 3 side, it is possible to determine whether the state of vehicle 10 is "parked" or not based on the vehicle's speed, the state of the vehicle's doors, and the on / off status of the ignition switch IG. Considering this, it is desirable that the in-vehicle unit 3 determines whether the state of vehicle 10 is "parked," "stopped," or "driving," and that when the state of vehicle 10 changes, the determination result from the in-vehicle unit 3 is notified to the tire sensor 2 (vehicle state synchronization). For example, it is desirable that the in-vehicle unit 3 determines whether the state of vehicle 10 is parked or stopped based on the vehicle's speed, the state of the vehicle's doors, and the on / off status of the ignition switch IG, and transmits the determination result to the tire sensor 2. With this, it is sufficient for the tire sensor 2 to receive information from the in-vehicle unit 3 side only once each time the state of vehicle 10 changes, so the power consumption of the tire sensor 2 can be sufficiently suppressed.

[0096] (Other embodiments) While representative embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above and can be modified in various ways, for example, as follows.

[0097] In the above-described embodiment, an example was shown in which theft detection of wheels 10a to 10d is performed based on the detection result from the acceleration sensor 22 in the parked state and the success or failure of communication between the tire sensor 2 and the in-vehicle unit 3 in the parked state, but the invention is not limited to this. Theft detection of wheels 10a to 10d may be performed based on either the detection result from the acceleration sensor 22 in the parked state or the success or failure of communication between the tire sensor 2 and the in-vehicle unit 3 in the parked state.

[0098] As described in the above-described embodiment, it is desirable that the wheel monitoring system performs detection processing such as tire replacement in addition to theft detection processing, but it is not limited to this, and for example, it may perform only one of the theft detection processing or the tire replacement detection processing.

[0099] In the above-described embodiment, when the in-vehicle unit 3 receives a theft signal from the tire sensor 2, it uses an alerting unit provided in the vehicle 10 to notify the theft of wheels 10a to 10d, but it is not limited to this. The in-vehicle unit 3 may also be configured to notify an external service center 73 or the like when it receives a theft signal from the tire sensor 2.

[0100] In the above-described embodiment, the state in which the doors are locked and the ignition switch IG is off is defined as the "parking state," and the state in which the ignition switch IG is on or the doors are unlocked is defined as the "stopped state," but the embodiment is not limited to this. The "parking state" is a state in which the driver is away from the vehicle 10 and the vehicle 10 cannot be immediately put into a driving state. The "stopped state" is a state in which the vehicle 10 can be immediately put into a driving state. For example, in the stopped state, the state in which the electronic key of the vehicle 10 cannot be detected by the onboard unit 3 may be defined as the "parking state," and the state in which the electronic key can be detected by the onboard unit 3 may be defined as the "stopped state."

[0101] Although the tire sensor 2 and the in-vehicle device 3 in the above-described embodiment are configured to communicate bidirectionally based on the BLE communication method, they may also be configured to communicate bidirectionally based on a communication method other than BLE.

[0102] In the embodiments described above, the wheel monitoring system of this disclosure was applied to a vehicle 10 having four wheels 10a to 10d as an example, but the wheel monitoring system of this disclosure can also be similarly applied to a vehicle 10 with a larger number of wheels.

[0103] In the embodiments described above, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where they are explicitly stated to be essential or where they are clearly considered essential in principle.

[0104] In the embodiments described above, if numerical values ​​such as the number, numerical values, quantities, or ranges of the components of the embodiment are mentioned, the embodiment is not limited to those specific numbers unless explicitly stated as particularly essential or clearly limited to a specific number in principle.

[0105] In the embodiments described above, when referring to the shape, positional relationships, etc. of the components, the definition is not limited to those shapes, positional relationships, etc., unless otherwise specifically stated or when the definition is fundamentally limited to a particular shape, positional relationship, etc.

[0106] In the embodiments described above, if it is stated that external environmental information (e.g., outside temperature) of the vehicle 10 is obtained from a sensor, it is also possible to eliminate the sensor and receive the external environmental information from a server or cloud outside the vehicle 10. Alternatively, it is also possible to eliminate the sensor, obtain related information concerning the external environmental information from a server or cloud outside the vehicle 10, and estimate the external environmental information from the obtained related information.

[0107] The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. The control unit and its method of this disclosure may be implemented in a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. The control unit and its method of this disclosure may be implemented in one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. The computer program may also be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. [Explanation of Symbols]

[0108] 10 vehicles 11 Car body 2 Tire Sensors 22 Accelerometer 23a Tire Monitoring Department 24 Tire Radio 3 Onboard equipment

Claims

1. A wheel monitoring system applicable to a vehicle (10) in which a plurality of wheels (10a to 10d), including tires, are attached to a vehicle body (11), A tire sensor (2) is provided on the wheel and includes an acceleration sensor (22) that outputs an acceleration that changes with the rotation of the wheel, The vehicle comprises an on-board unit (3) provided on the vehicle body, The tire sensor and the in-vehicle device are configured to communicate bidirectionally. The in-vehicle unit determines whether the vehicle is parked, stopped, or driving based on the vehicle's speed, the state of the vehicle's doors, and the on / off status of the vehicle's ignition switch, and transmits information including the determination result to the tire sensor. A wheel monitoring system comprising a tire sensor that identifies the current state of the vehicle based on the information notified from the in-vehicle device, and determines whether the wheel has been stolen and whether it is possible that the tire has been rotated or replaced, based on the combination of the identified state of the vehicle and the sensor output of the acceleration sensor.

2. The aforementioned in-vehicle device is When the aforementioned driving speed is below a predetermined value, the vehicle's doors are locked, and the ignition switch is off, it is determined that the vehicle is in the parked state. If the aforementioned driving speed is less than the predetermined value, the ignition switch is on, or the vehicle doors are unlocked, it is determined that the vehicle is in the stationary state. The wheel monitoring system according to claim 1, wherein the system determines that the state of the vehicle is the driving state when the driving speed is equal to or greater than the predetermined value and the ignition switch is turned ON.

3. The wheel monitoring system according to claim 1 or 2, wherein the tire sensor determines that the wheel has been stolen when a predetermined change in acceleration is detected by the acceleration sensor while the vehicle is parked.

4. The wheel monitoring system according to claim 1 or 2, wherein the tire sensor determines that the tire may have been rotated or replaced when a predetermined change in acceleration is detected by the acceleration sensor while the vehicle is stationary.

5. The aforementioned tire recovery is When a predetermined change in acceleration is detected by the acceleration sensor in the aforementioned parking state, it is determined that the wheel has been stolen. The wheel monitoring system according to claim 1 or 2, wherein, in the aforementioned stationary state, if the acceleration sensor detects the change in acceleration, it is determined that the tire may have been rotated or replaced.

6. The aforementioned in-vehicle device is In the aforementioned driving conditions, if the rotation of any of the previously registered wheels is not detected, it is determined that a tire change has been performed. The wheel monitoring system according to claim 5, which determines that the tire change has not been performed when the rotation of all of the pre-registered wheels is detected in the aforementioned driving conditions.

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