Tire position reversal detection device, method, and program

Abstract

This technology provides a mechanism for detecting changes in the mounting position of tires on a vehicle. [Solution] The tire position swap detection device comprises an acquisition unit, a first calculation unit, a second calculation unit, and a swap determination unit. The acquisition unit acquires the rotational speed of each tire while the vehicle is running. The first calculation unit calculates a first index. The second calculation unit calculates a second index. The swap determination unit determines, based on the first and second indices, whether or not the mounting positions of the tires were swapped before the vehicle ran. The swap determination unit determines that the tires were swapped before the vehicle ran if the change from the initial value of the first index exceeds a predetermined first threshold, and the change from the initial value of the second index is less than or equal to a predetermined second threshold.

Description

[Technical Field]

[0001] The present invention relates to a tire position reversal detection device, a tire position reversal detection method, and a tire position reversal detection program for detecting the reversal of the mounting position of tires in a vehicle. [Background technology]

[0002] Traditionally, systems that automatically detect tire pressure reduction (Tire Pressure Monitoring Systems; TPMS) have been studied. For example, there are TPMS systems that follow the Dynamic Loaded Radius (DLR) method. The DLR method utilizes the phenomenon that a depressurized tire deforms during driving, reducing its dynamic load radius and allowing it to rotate at a higher speed. It estimates tire pressure reduction from the tire's rotation speed.

[0003] Patent Document 1 discloses depressurization indices DEL1 to DEL3 for estimating depressurization according to the DLR method. In Patent Document 1, DEL1 to DEL3 are defined as follows. However, V1 to V4 are the rotational speeds of the left front wheel, right front wheel, left rear wheel, and right rear wheel tires, respectively. DEL1=[(V1+V4) / (V2+V3)-1]×100(%) DEL2=[(V1+V2) / (V3+V4)-1]×100(%) DEL3=[(V1+V3) / (V2+V4)-1]×100(%)

[0004] In the pressure reduction determination using the pressure reduction indicators DEL1 to DEL3 described above, reference values ​​for pressure reduction indicators DEL1 to DEL3 are pre-stored in the vehicle. The reference values ​​are the values ​​of pressure reduction indicators DEL1 to DEL3 under the assumption that all of the left front wheel, right front wheel, left rear wheel, and right rear wheel tires are within the normal internal pressure range. If the difference between the current pressure reduction indicators DEL1 to DEL3 and the stored reference values ​​is greater than or equal to a threshold, it is estimated that at least one of the above tires has reduced pressure. Here, as disclosed in Patent Document 1, in order to make an accurate pressure reduction determination, it is necessary to update the reference values ​​stored in the vehicle after adjusting the tire pressure. Normally, the update of the reference values ​​is performed by an initialization instruction from the user to the vehicle. Patent Document 1 discloses a technology that issues an initialization forgetting alarm when it is determined that the tire pressure has been adjusted but no initialization instruction from the user is detected. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-149340 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the technology disclosed in Patent Document 1, the conditions for issuing an initialization forgetting alarm are to first determine whether a pressure drop of a level that would trigger a pressure drop alarm has occurred, and then determine whether the tire pressure has returned to the normal range (whether the air pressure has been adjusted). In other words, in the technology disclosed in Patent Document 1, if the tire pressure is outside the normal pressure range at the first timing and then returns to the normal pressure range at the subsequent second timing, an initialization forgetting alarm may be output. However, since the reference values ​​of the pressure drop indices DEL1 to DEL3 also change before and after the tire mounting position is changed, it is preferable to update the reference values ​​in such cases in order to improve the accuracy of pressure drop detection. However, in the technology disclosed in Patent Document 1, if no pressure drop alarm was output at the timing before the change, it was not possible to issue an initialization forgetting alarm.

[0007] The present invention aims to provide a technology for detecting the reversal of the mounting position of tires on a vehicle. [Means for solving the problem]

[0008] A tire position swap detection device according to a first aspect of the present invention comprises an acquisition unit, a first calculation unit, a second calculation unit, and a swap determination unit. The acquisition unit acquires the rotational speed of each tire mounted at the left front position, the right front position, the left rear position, and the right rear position, respectively, while the vehicle is in motion and has at least the left front position, the right front position, the left rear position, and the right rear position on which tires are mounted. The first calculation unit calculates a first index that compares the rotational speed of the tire mounted at the left front position and the rotational speed of the tire mounted at the right rear position with the rotational speed of the tire mounted at the right front position and the rotational speed of the tire mounted at the left rear position, or a first index that compares the rotational speed of the tire mounted at the left front position and the rotational speed of the tire mounted at the right front position with the rotational speed of the tire mounted at the left rear position and the rotational speed of the tire mounted at the right rear position. The second calculation unit calculates a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. The swapping determination unit determines, based on the first index and the second index, whether or not the tire mounting positions were swapped before the vehicle was driven. The swapping determination unit determines that the tires were swapped between the front left position and the rear left position before the vehicle was driven, and that the tires were swapped between the front right position and the rear right position before the vehicle was driven, if the change from the initial value of the first index exceeds a predetermined first threshold and the change from the initial value of the second index is less than or equal to a predetermined second threshold.

[0009] The tire position swap detection device relating to the second aspect comprises an acquisition unit, a first calculation unit, a second calculation unit, and a swap determination unit. The acquisition unit acquires the rotational speed of each tire mounted at the left front position, the right front position, the left rear position, and the right rear position, respectively, while the vehicle is in motion and has at least the left front position, the right front position, the left rear position, and the right rear position where tires are mounted. The first calculation unit calculates a first index that compares the rotational speed of the tire mounted at the left front position and the rotational speed of the tire mounted at the left rear position with the rotational speed of the tire mounted at the right front position and the rotational speed of the tire mounted at the right rear position, or a first index that compares the rotational speed of the tire mounted at the left front position and the rotational speed of the tire mounted at the right front position with the rotational speed of the tire mounted at the left rear position and the rotational speed of the tire mounted at the right rear position. The second calculation unit calculates a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. The swapping determination unit determines, based on the first index and the second index, whether or not the tire mounting positions were swapped before the vehicle was driven. The swapping determination unit determines that the tires were swapped between the front left position and the rear right position before the vehicle was driven, and that the tires were swapped between the front right position and the rear left position before the vehicle was driven, if the change from the initial value of the first index exceeds a predetermined first threshold and the change from the initial value of the second index is less than or equal to a predetermined second threshold.

[0010] The tire position swap detection device relating to the third viewpoint is a tire position swap detection device relating to the first or second viewpoint, further comprising a determination unit that determines, based on a rotational speed signal representing the rotational speed of each tire, a first torsional resonance frequency of the tire mounted at the left front position and a second torsional resonance frequency of the tire mounted at the right front position, or based on the rotational speed of each tire, a first torsional resonance frequency of the tire mounted at the left rear position and a second torsional resonance frequency of the tire mounted at the right rear position. The swap determination unit determines that the tire swap occurred before the vehicle was driven if the change from the initial value of the first indicator exceeds a predetermined first threshold, the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, the change from the initial value of the first torsional resonance frequency is less than or equal to a predetermined third threshold, and the change from the initial value of the second torsional resonance frequency is less than or equal to a predetermined fourth threshold.

[0011] The tire position change detection device relating to the fourth viewpoint is a tire position change detection device relating to any of the first viewpoint or the third viewpoint, and further comprises a notification unit that generates a notification prompting the user of the vehicle to perform an initialization operation when it is determined that the tire change occurred before the vehicle was driven.

[0012] The tire position swap detection method relating to the fifth aspect is a tire position swap detection method performed by one or more computers, and comprises the following: - To obtain the rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions while the vehicle is in motion, the vehicle having at least the front left, front right, rear left, and rear right positions on which tires are mounted. - Calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position, or calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position. - Calculate a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. Based on the first and second indicators, determine whether or not the mounting position of the tires was changed before the vehicle was driven. The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the left rear position before the vehicle was driven, and that the tires were swapped between the right front position and the right rear position before the vehicle was driven.

[0013] The tire position swap detection method relating to the sixth aspect is a tire position swap detection method performed by one or more computers, and comprises the following: - To obtain the rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions while the vehicle is in motion, the vehicle having at least the front left, front right, rear left, and rear right positions on which tires are mounted. - Calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position, or calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position. - Calculate a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. Based on the first and second indicators, determine whether or not the mounting position of the tires was changed before the vehicle was driven. The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the right rear position before the vehicle was driven, and that the tires were swapped between the right front position and the left rear position before the vehicle was driven.

[0014] The tire position swap detection program related to the seventh perspective causes one or more computers to perform the following: - To obtain the rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions while the vehicle is in motion, the vehicle having at least the front left, front right, rear left, and rear right positions on which tires are mounted. - Calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position, or calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position. - Calculate a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. Based on the first and second indicators, determine whether or not the mounting position of the tires was changed before the vehicle was driven. The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the left rear position before the vehicle was driven, and that the tires were swapped between the right front position and the right rear position before the vehicle was driven.

[0015] The tire position swap detection program related to the eighth perspective causes one or more computers to perform the following: - To obtain the rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions while the vehicle is in motion, the vehicle having at least the front left, front right, rear left, and rear right positions on which tires are mounted. - Calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position, or calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position. - Calculate a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. Based on the first and second indicators, determine whether or not the mounting position of the tires was changed before the vehicle was driven. The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the right rear position before the vehicle was driven, and that the tires were swapped between the right front position and the left rear position before the vehicle was driven. [Effects of the Invention]

[0016] According to the present invention, a technology is provided for detecting the reversal of the mounting position of tires on a vehicle. [Brief explanation of the drawing]

[0017] [Figure 1] A schematic diagram showing how a tire position replacement detection device according to one embodiment of the present invention is mounted on a vehicle. [Figure 2] A block diagram showing the electrical configuration of the detection device. [Figure 3A] A flowchart illustrating the process for detecting tire position swaps. [Figure 3B] Continuation of Figure 3A. [Figure 4] A diagram illustrating one example of how to swap tire positions. [Figure 5] A diagram illustrating one example of how to swap tire positions. [Modes for carrying out the invention]

[0018] Hereinafter, with reference to the drawings, a tire position repositioning detection device, a tire position repositioning detection method, and a tire position repositioning detection program according to embodiments of the present invention will be described.

[0019] <1. Overall Structure> Figure 1 is a schematic diagram showing how the tire position reversal detection device 2 (hereinafter also simply referred to as "detection device 2") according to this embodiment is mounted on a vehicle 1. The vehicle 1 is an automobile and may be equipped with an internal combustion engine as a prime mover, an electric motor, or both. The vehicle 1 according to this embodiment is a front-engine, front-drive four-wheeled vehicle and includes a left front position FL, a right front position FR, a left rear position RL, and a right rear position RR. The left front position FL and the right front position FR are located at both ends of the front axle, and the left rear position RL and the right rear position RR are located at both ends of the rear axle, and each is equipped with a mechanism (for example, a wheel hub) for mounting tires T1 to T4 (hereinafter also referred to as "tire-wheel assemblies T1 to T4") attached to rim wheels. In Figure 1, the tire and wheel assemblies T1 to T4 are mounted on the left front position FL, the right front position FR, the left rear position RL, and the right rear position RR, respectively. However, for reasons such as suppressing uneven tire wear, the mounting positions on vehicle 1 may be swapped.

[0020] The detection device 2 detects when the mounting positions of the tire and wheel assemblies T1 to T4 are swapped on vehicle 1. When a swap in mounting positions is detected, the detection device 2 notifies the user of vehicle 1 (typically the driver) via the display unit 3 mounted on vehicle 1, prompting them to perform an initialization operation. An initialization operation is a user operation necessary for more accurate pressure reduction detection of the tire and wheel assemblies T1 to T4 in the DLR type TPMS mounted on vehicle 1. When the user performs an initialization operation by operating the operation unit 4 of vehicle 1, which will be described later, the detection device 2 receives this as an initialization instruction from the user. Upon receiving the initialization instruction, the detection device 2 sends an initialization signal to the on-board ECU (Electronic Control Unit) that constitutes the TPMS. The initialization signal is a signal requesting the initialization of the reference value used in the pressure reduction detection process performed by the on-board ECU. Details of this tire position swap detection process and initialization process will be described later.

[0021] Vehicle 1 is equipped with wheel speed sensors 6, corresponding to the left front position FL, right front position FR, left rear position RL, and right rear position RR. Each wheel speed sensor 6 detects the rotational speed of the tire-wheel assemblies T1 to T4 mounted at its corresponding mounting position and outputs a rotational speed signal representing these rotational speeds. The wheel speed sensors 6 are connected to the detection device 2 via a communication line 5 or wirelessly, enabling data communication. The rotational speed signals output by the wheel speed sensors 6 are sequentially transmitted to the detection device 2 along with information identifying the wheel speed sensor 6.

[0022] Any wheel speed sensor 6 that can detect the rotational speed of the tire and wheel assemblies T1 to T4 can be used. For example, a sensor that measures rotational speed from the output signal of an electromagnetic pickup can be used, or a sensor that generates electricity using rotation, such as a dynamo, and measures rotational speed from the voltage generated at that time can be used. The specific mounting position of the wheel speed sensor 6 is not particularly limited and can be appropriately selected depending on the type of sensor, as long as it is possible to detect the rotational speed.

[0023] The display unit 3 is not particularly limited as long as it can display various notifications to the user, and can be implemented in any form, such as a liquid crystal display element, a liquid crystal monitor, or an organic EL display. If the display unit 3 is configured as a touch panel display, it may also serve as the operation unit 4 described later. The installation location of the display unit 3 can also be selected as appropriate, but it is preferable to install it in a location that is easily visible to the user, such as on the instrument panel. If the detection device 2 is connected to a car navigation system, it is also possible to use the car navigation monitor as the display unit 3. When a monitor is used as the display unit 3, various notifications can be displayed as icons or text information on the monitor.

[0024] The operation unit 4 is a mechanism for the user to issue initialization instructions to the detection device 2 by operating it. The operation unit 4 is not particularly limited as long as it allows user operation, and can be implemented in any form, such as a push button, a switch-type lever, a rotary dial, or a touch panel display. The installation location of the operation unit 4 can also be selected as appropriate, but it is preferable to install it in a location that is easily accessible to the user, such as on the instrument panel. Furthermore, the operation unit 4 may be configured to light up when it is necessary to attract the user's attention, for example by incorporating a light-emitting element such as an LED, and to turn off the light when the user's initialization operation is completed.

[0025] <2. Detection device> Figure 2 is a block diagram showing the electrical configuration of the detection device 2. The detection device 2 is, in terms of hardware, an on-board ECU mounted on the vehicle 1, and as shown in Figure 2, comprises an I / O interface 11, a CPU (Central Processing Unit) 12, a ROM (Read Only Memory) 13, a RAM (Random Access Memory) 14, and a non-volatile, rewritable storage device 15. These elements are electrically connected to each other. The I / O interface 11 is a communication device that enables communication with external devices such as the display unit 3, the operation unit 4, the wheel speed sensor 6, and other ECUs. The ROM 13 stores a program 9 for controlling the operation of various parts of the vehicle 1. The program 9 is written to the ROM 13 via a storage medium 8 such as a CD-ROM, or via a programmer such as a chip programmer. The CPU 12 reads the program 9 from the ROM 13 and executes it, thereby virtually operating as an acquisition unit 20, a first calculation unit 21, a second calculation unit 22, a identification unit 23, a replacement determination unit 24, a notification unit 25, and an initialization unit 26. Details of the operation of each part 20-26 will be described later. The storage device 15 consists of a hard disk, flash memory, EPROM, etc., and mainly constitutes the storage area of ​​the detection device 2. Note that the storage location of the program 9 may be the storage device 15 instead of the ROM 13. The RAM 14 and storage device 15 are used as appropriate for calculations by the CPU 12.

[0026] The detection device 2 may be configured integrally with the on-board ECU that constitutes the TPMS and performs pressure reduction detection processing for tire and wheel assemblies T1 to T4, or it may be configured as a separate on-board ECU.

[0027] <3. Tire position swap detection process> The following describes an example of the tire position swap detection process and initialization process performed by the detection device 2, with reference to Figures 3A and 3B. The flowchart shown in Figures 3A and 3B starts, for example, when the electrical system switch of vehicle 1 is turned ON, is repeated once or multiple times, and ends when vehicle 1 stops and a certain amount of time has elapsed.

[0028] In step S1, the acquisition unit 20 determines whether the vehicle has been stopped for a certain period of time or longer. As a prerequisite, the swapping of the mounting positions of the tire and wheel assemblies T1 to T4 is performed when the engine of vehicle 1 has been stopped for a certain period of time or longer. The determination in step S1 is whether the above prerequisite is met. The acquisition unit 20 can perform the determination in step S1 by, for example, communicating with the control unit that controls the engine of vehicle 1 and obtaining the time during which the engine has been continuously in the off state. If it is determined in step S1 that "it has been stopped for a certain period of time or longer (YES)", then step S2 is executed. Step S2 is not executed until it is determined in step S1 that "it has been stopped for a certain period of time or longer (YES)".

[0029] In step S2, the acquisition unit 20 acquires time-series rotational speed signals from each wheel speed sensor 6, which is mounted corresponding to the left front position FL, right front position FR, left rear position RL, and right rear position RR. The acquisition unit 20 converts the acquired rotational speed signals into rotational speeds V1 to V4 of the tire-wheel assemblies T1 to T4 and stores them in RAM 14 or storage device 15. Here, the rotational speeds of the tire-wheel assemblies mounted at the left front position FL, right front position FR, left rear position RL, and right rear position RR are converted into rotational speed V1 to V4, respectively. FL , V FR , V RL, V RR is referred to as distinct from it. When the tire-wheel assemblies T1 to T4 are mounted on the vehicle 1 as shown in FIG. 1, V1 corresponds to V FL to, V2 corresponds to V FR to, V3 corresponds to V RL to, V4 corresponds to V RR respectively. Here, for the rotational speeds V1 and V2 of the tire-wheel assemblies T1 and T2, correction processing considering slip due to being a driving wheel may be appropriately performed.

[0030] In step S3, the first calculation unit 21 calculates the first index DEL1 based on the rotational speeds V1 to V4. DEL1 is defined as in the following formula (1) in the present embodiment, and V in formula (1) FL , V FR , V RL , V RR are respectively substituted with V1, V2, V3, and V4 at the same time. As can be seen from formula (1), DEL1 is an index for comparing the rotational speed V FL and the rotational speed V RR with the rotational speed V FR and the rotational speed V RL . Note that DEL1 is also a pressure reduction index for detecting pressure reduction of the tire-wheel assembly in the DLR method.

Equation

[0031] In step S4, the second calculation unit 22 calculates the second index DEL3 based on the rotational speeds V1 to V4. DEL3 is defined as in the following formula (2) in the present embodiment, and V in formula (2) FL , V FR , V RL , V RR are respectively substituted with V1, V2, V3, and V4 at the same time. As can be seen from formula (2), DEL3 is the rotational speed V FL and the rotational speed V RL with the rotational speed V FR and the rotational speed V RRIt is an index used for comparison. Furthermore, like DEL1, DEL3 is also a pressure reduction index used in the DLR method to detect pressure reduction in the tire and wheel assembly.

number

[0032] In step S5, the specific unit 23 rotates at a rotational speed V FL , V FR Based on the rotational speed signal representing the rotational speed V1, the torsional resonance frequency of the tire mounted on the front axle is identified. Specifically, the identification unit 23 identifies the first torsional resonance frequency ω of the tire included in the tire-wheel assembly T1 mounted at the left front position FL, based on the rotational speed signal representing the rotational speed V1. FL The identification unit 23 identifies the second torsional resonance frequency ω of the tire included in the tire-wheel assembly T2 mounted at the right front position FR, based on the rotational speed signal representing the rotational speed V2. FR Identify.

[0033] First torsional resonance frequency ω FL The method for identifying the first torsional resonance frequency (G(f)) is not particularly limited, but for example, it can be done as follows. First, the identification unit 23 assumes a transfer function G(s) that takes the input u from the road surface as input and the rotational speed θ as output. The identification unit 23 applies white noise to the input u and the rotational speed V1 to the rotational speed θ, and identifies the transfer function G(s) by sequential updating. Next, the identification unit 23 converts the transfer function G(s) into a frequency domain function G(f) by substituting s=jω(ω=2πf) into the transfer function G(s). Furthermore, the identification unit 23 calculates the power spectrum of G(f) and identifies the f at which the power spectrum of G(f) is maximized as the first torsional resonance frequency ω FL It is identified as follows. The identified part 23 is the second torsional resonance frequency ω FR The same procedure can be applied to this as well.

[0034] After the determination in step S1 is "YES", the following steps S2 to S5 may be repeated multiple times consecutively. That is, the acquisition unit 20 may acquire multiple datasets of rotation speeds V1 to V4 at the same time in chronological order. The first calculation unit 21 may calculate multiple first indicators DEL1 in chronological order based on the chronological datasets of rotation speeds V1 to V4, and the second calculation unit 22 may calculate multiple second indicators DEL3 in chronological order based on the chronological datasets of rotation speeds V1 to V4. The identification unit 23 determines the first torsional resonance frequency ω in chronological order based on the chronological datasets of rotation speeds V1 to V4. FL and the second torsional resonance frequency ω FR You may specify multiple items.

[0035] In step S6, the replacement determination unit 24 determines the first index DEL1, the second index DEL3, and the first torsional resonance frequency ω FL and the second torsional resonance frequency ω FR The initial values ​​for each are DEL1_0, DEL3_0, and ω. FL _0 and ω FR Determine whether _0 is already stored in memory device 15. Initial values ​​DEL1_0, DEL3_0, ω FL _0 and ω FR _0 represents the first index DEL1, the second index DEL3, and the first torsional resonance frequency ω, respectively, obtained under the condition that all tire-wheel assemblies T1 to T4 are within the normal internal pressure range. FL and the second torsional resonance frequency ω FR These are the values ​​(including the average value). These initial values ​​are necessary for determining the swap of the tire mounting positions later. The swap determination unit 24 determines the initial values ​​DEL1_0, DEL3_0, ω FL _0 and ω FR If it is determined that _0 is already stored in the memory device 15 (YES), then step S8 is executed. The replacement determination unit 24 determines the initial values ​​DEL1_0, DEL3_0, ω FL _0 and ω FR If it is determined that _0 has not yet been stored in the memory device 15 (NO), then step S7 is executed.

[0036] In step S7, the replacement determination unit 24 determines the first index DEL1, the second index DEL3, and the first torsional resonance frequency ω obtained in steps S3 to S5. FL and the second torsional resonance frequency ω FR The values ​​of DEL1_0, DEL3_0, and ω are set to their initial values ​​respectively. FL _0 and ω FR It is saved as _0 in storage device 15. These initial values ​​may be the average value of the time series data, etc. After step S7, step S1 is executed again.

[0037] In step S8, the replacement determination unit 24 determines the first index DEL1, the second index DEL3, and the first torsional resonance frequency ω obtained in steps S3 to S5. FL and the second torsional resonance frequency ω FR Based on at least one of the following, it is determined whether or not a pressure reduction has occurred in at least one of the tire-wheel assemblies T1 to T4. This determination is made, for example, by |DEL1-DEL1_0|, |DEL3-DEL3_0|, |ω FL -ω FL _0| and |ω FR -ω FR This is done by comparing each of _0| with a predetermined pressure reduction threshold. The pressure reduction threshold is, for example, DEL1, DEL3, ω when any one of the tire and wheel assemblies T1 to T4 is reduced by 15% to 20% from the normal internal pressure. FL , ω FR The value is predetermined based on the value and stored in the storage device 15. If the replacement determination unit 24 determines that a pressure drop has occurred in at least one of the tire-wheel assemblies T1 to T4 (YES), the tire position replacement detection process is terminated because it is necessary to perform higher-priority processing in the TPMS, such as identifying the tire-wheel assembly with the pressure drop and issuing an alarm to the user. If the replacement determination unit 24 determines that a pressure drop (to an alarm level) has not occurred in any of the tire-wheel assemblies T1 to T4 (NO), then step S9 is executed.

[0038] In step S9, the replacement determination unit 24 makes a determination based on the first indicator DEL1 and the second indicator DEL3. Specifically, the replacement determination unit 24 compares |DEL1-DEL1_0|=ΔDEL1, which is the absolute value of the difference between the first indicator DEL1 calculated in step S3 and the initial value DEL1_0, with a predetermined first threshold Th1. Similarly, the replacement determination unit 24 compares |DEL3-DEL3_0|=ΔDEL3, which is the absolute value of the difference between the second indicator DEL3 calculated in step S4 and the initial value DEL3_0, with a predetermined second threshold Th2. The first threshold Th1 and the second threshold Th2 are different from the above-mentioned depressurization thresholds, and are each approximately 1 / 3 of the above-mentioned depressurization thresholds. Therefore, even if ΔDEL1 exceeds the first threshold Th1 or ΔDEL3 exceeds the second threshold Th2, it is not immediately determined that a depressurization at an alarm level has occurred. The first threshold Th1 and the second threshold Th2 may be the same value or may be different values. When the swapping determination unit 24 determines that ΔDEL1 exceeds the first threshold Th1 (ΔDEL1>Th1) and ΔDEL3 is less than or equal to the second threshold Th2 (ΔDEL3≦Th2) (YES), step S10 is executed next. Alternatively, when the swapping determination unit 24 determines that ΔDEL1 is less than or equal to the first threshold Th1 (ΔDEL1≦Th1) and ΔDEL3 exceeds the second threshold Th2 (ΔDEL3>Th2) (YES), step S10 is executed next. When the swapping determination unit 24 determines that ΔDEL1 and ΔDEL3 do not satisfy the above conditions (NO), step S1 is executed next. In other words, if ΔDEL1≦Th1 and ΔDEL3≦Th2, or if ΔDEL1>Th1 and ΔDEL3>Th2, it is determined that there was no change in the mounting positions of the tire and wheel assemblies T1 to T4 when vehicle 1 stopped immediately before the current run.

[0039] This determination is based on the following principle. Assume that immediately before the current vehicle 1 was driven, the mounting positions of the tire-wheel assemblies T1-T4 were swapped, and that the tire-wheel assemblies T1-T4, which were originally mounted as shown on the left in Figure 4, are now mounted as shown in Figure 1 (right in Figure 4). In other words, assume that tire-wheel assemblies T4 and T1 were swapped between the left front position FL and the right rear position RR, and tire-wheel assemblies T3 and T2 were swapped between the right front position FR and the left rear position RL. Assume that at the time before and after the swap, all tire-wheel assemblies T1-T4 were at normal internal pressure. In this case, during the drive before the swap, V in equations (1) and (2) FL , V FR , V RL , V RR V4, V3, V2, and V1 are substituted respectively, and during the run after the substitution, the V in equations (1) and (2) FL , V FR , V RL , V RR V1, V2, V3, and V4 are substituted into these values, respectively. As a result, theoretically, the value of DEL1 does not change before and after the swap, while theoretically, the sign of the value of DEL3 is reversed. Therefore, threshold values ​​for values ​​that can be considered unchanged from their respective initial values ​​are predetermined as the first threshold Th1 and the second threshold Th2, and stored in the memory device 15. Based on ΔDEL1 and ΔDEL3, it is possible to determine whether or not a swap of mounting positions as shown in Figure 4 has occurred.

[0040] Furthermore, immediately before the current vehicle 1 was driven, the mounting positions of the tire and wheel assemblies T1 to T4 were swapped. Originally, the tire and wheel assemblies T1 to T4 were mounted as shown on the left in Figure 5, but now they are mounted as shown in Figure 1 (right in Figure 5). In other words, the tire and wheel assemblies T3 and T1 were swapped between the left front position FL and the left rear position RL, and the tire and wheel assemblies T4 and T2 were swapped between the right front position FR and the right rear position RR. It should be assumed that at the time before and after the swap, all tire and wheel assemblies T1 to T4 were at normal internal pressure. In this case, during the drive before the swap, V in equations (1) and (2) FL , V FR, V RL , V RR V3, V4, V1, and V2 are substituted respectively, and during the run after the substitution, the V in equations (1) and (2) FL , V FR , V RL , V RR V1, V2, V3, and V4 are substituted into these values, respectively. As a result, the value of DEL3 theoretically remains unchanged before and after the swap, while the sign of the value of DEL1 theoretically reverses. Therefore, based on the first threshold Th1 and the second threshold Th2, as well as ΔDEL1 and ΔDEL3, it is possible to determine whether or not a swap of mounting positions as shown in Figure 5 has occurred.

[0041] In summary, if ΔDEL1 > Th1 and ΔDEL3 ≤ Th2 holds, it can be determined that there was an exchange of the tire-wheel assembly between the left front position FL and the left rear position RL, and between the right front position FR and the right rear position RR. Also, if ΔDEL1 ≤ Th1 and ΔDEL3 > Th2 holds, it can be determined that there was an exchange of the tire-wheel assembly between the left front position FL and the right rear position RR, and between the right front position FR and the left rear position RL. However, if tire-wheel assemblies T1 and T4 are depressurized to the same extent, or if tire-wheel assemblies T2 and T3 are depressurized to the same extent, ΔDEL1 > Th1 and ΔDEL3 ≤ Th2 can still hold even if there was no exchange of mounting positions. Similarly, if tire and wheel assemblies T1 and T3 are depressurized to the same extent, or if tire and wheel assemblies T2 and T4 are depressurized to the same extent, then ΔDEL1 ≤ Th1 and ΔDEL3 > Th2 may also be true. Therefore, in order to distinguish between two-wheel depressurization and swapping of mounting positions, step S10 is performed.

[0042] Referring to Figure 3A, in step S10, the replacement determination unit 24 determines the first torsional resonance frequency ω FL and the second torsional resonance frequency ω FR A determination is made based on the following. Specifically, the replacement determination unit 24 determines the first torsional resonance frequency ω identified in step S5. FL And the initial value ω FL|ω, which is the absolute value of the difference from _0 FL -ω FL _0| = Δω FL is compared with a predetermined third threshold Th3. The third threshold Th3 is, for example, Δω when the tire-wheel assemblies T1 to T4 are mounted at the left front position FL and the pressure is reduced by 5% to 15% from the normal internal pressure FL and is determined in advance based on the value and stored in the storage device 15. Also, the replacement determination unit 24 determines the second torsional resonance frequency ω FR specified in step S5, and the absolute value of the difference from the initial value ω FR _0, that is, |ω FR -ω FR _0| = Δω FR is compared with a predetermined fourth threshold Th4. The fourth threshold Th4 is determined in advance in the same manner as the third threshold and stored in the storage device 15. When the tire-wheel assemblies T1 to T4 are all within the normal internal pressure range and the mounting positions are swapped, the first torsional resonance frequency ω FL and the second torsional resonance frequency ω FR do not theoretically change from the initial values. Therefore, when the change of the first torsional resonance frequency ω FL from its initial value ω FL _0 is not more than the third threshold Th3 (Δω FL ≤ Th3), and the change of the second torsional resonance frequency ω FR from its initial value ω FR _0 is not more than the fourth threshold Th4 (Δω FR ≤ Th4), the replacement determination unit 24 determines that there has been a swap of the mounting positions (YES), and when it is other than Δω FL ≤ Th3 and Δω FR ≤ Th4, determines that there has been no swap of the mounting positions (NO).

[0043] In step S10, when the replacement determination unit 24 determines that there has been no swap of the mounting positions (NO), the tire position swap detection process ends. In step S10, when the replacement determination unit 24 determines that there has been a swap of the mounting positions (YES), step S11 in FIG. 3B is executed.

[0044] In step S11, the notification unit 25 issues a notification prompting the user to perform an initialization operation. Specifically, the notification unit 25 creates message data such as "Please perform an initialization operation when tire rotation is performed" and outputs this to the display 3. However, the form of the notification is not limited to a message in characters, and may be a graphic indicating the initialization operation, voice data of the above message, or a buzzer sound, etc. In addition to or instead of the display 3, it may be output from a speaker installed in the vehicle. Furthermore, the notification unit 25 may, in addition to or instead of this, light up the operation unit 4.

[0045] In step S12, the initialization unit 26 determines whether an initialization operation has been performed by the user, that is, whether an initialization instruction via the operation unit 4 has been received. When the initialization unit 26 determines that an initialization operation has been performed (YES), step S13 is then executed. On the other hand, when the initialization unit 26 determines that an initialization operation has not been performed (NO), step S11 is executed again. That is, in the detection device 2, until an initialization operation is performed, the notification unit 25 can continuously or intermittently issue a notification prompting the initialization operation.

[0046] In step S13, the initialization unit 26 transmits an initialization signal to the in-vehicle ECU that constitutes the TPMS and performs a decompression detection process for the tire-wheel assemblies T1 to T4. The initialization signal is currently a signal that requests resetting the reference values of the decompression indicators DEL1, DEL3, and DEL2 stored in the storage area of the in-vehicle ECU and newly acquiring and updating them. In the present embodiment, the reference values of DEL1 and DEL3 are the same as the initial values DEL1_0 and DEL3_0, respectively. Note that the decompression indicator DEL2 is defined as in the following formula (3) in the present embodiment. When the tire-wheel assemblies T1 to T4 are mounted as shown in FIG. 1, V in formula (3) FL , V FR , V RL , V RR is substituted with V1, V2, V3, and V4 at the same time, respectively.

Equation

[0047] Upon receiving the initialization signal, the in-vehicle ECU resets the currently stored reference values ​​for pressure reduction indices DEL1 to DEL3 and overwrites them in the memory with newly calculated values ​​for pressure reduction indices DEL1 to DEL3 (including the average value) as the reference values. This allows for more accurate pressure reduction detection processing based on the latest pressure reduction indices DEL1 to DEL3 and the reference values ​​for pressure reduction indices DEL1 to DEL3 after the replacement of tire and wheel assemblies T1 to T4.

[0048] Furthermore, the initialization unit 26 initializes the initial values ​​stored in the memory device 15 in step S7, namely DEL1_0, DEL3_0, and ω. FL _0 and ω FR The value of _0 is reset. Then, when steps S1 to S5 are executed again, in the judgment of step S6, the swap judgment unit 24 determines the initial values ​​DEL1_0, DEL3_0, ω FL _0 and ω FR The unit determines that _0 is not yet stored in the memory device 15 (NO). The replacement determination unit 24 then determines the first index DEL1 and the second index DEL3 calculated in steps S3 and S4, and the first torsional resonance frequency ω identified in step S5. FL and the second torsional resonance frequency ω FR This value is overwritten and saved to storage device 15 as the initial value.

[0049] <4. Features> (1) According to the detection device 2 of the above embodiment, even if the user forgets to perform the initialization operation on the TPMS after swapping the mounting positions of the tire and wheel assemblies T1 to T4, this can be notified. Therefore, pressure reduction detection of the tire and wheel assemblies T1 to T4 can be performed without degrading the accuracy due to the swapping.

[0050] (2) According to the detection device 2 of the above embodiment, it is possible to distinguish whether a change in the first indicator DEL1 or the second indicator DEL3 is due to the swapping of the mounting positions of the tire and wheel assemblies T1 to T4, or due to pressure reduction in specific two wheels of the tire and wheel assemblies T1 to T4. Therefore, it is possible to reduce the possibility of issuing a notification prompting the user to perform an initialization operation by mistake when the user has not performed a swap.

[0051] (3) According to the detection device 2 of the above embodiment, it is possible to distinguish between two different swaps of the mounting positions of the tire and wheel assemblies T1 to T4, as shown in Figures 4 and 5.

[0052] <5. Variation> Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0053] (1) In the above embodiment, the detection device 2 determined whether the following conditions were met, with DEL1 as the first index and DEL3 as the second index: ΔDEL1>Th1 and ΔDEL3≦Th2, or ΔDEL1≦Th1 and ΔDEL3>Th2. However, the detection device 2 may only determine whether either one of these conditions is met. For example, if the types of tire and wheel assemblies T1 to T4 to be mounted on the vehicle 1 are predetermined, and the design of the tire and wheel assemblies T1 to T4 specifies the swapping shown in Figure 5, the detection device 2 may only determine whether the following conditions are met: ΔDEL1≦Th1 and ΔDEL3>Th2. In this case, DEL3 can be applied to the first index of the present invention, DEL1 to the second index of the present invention, threshold Th1 to the second threshold of the present invention, and threshold Th2 to the first threshold of the present invention.

[0054] (2) DEL1 or DEL3 as the first indicator is not limited to those in the above embodiment, and for example, DEL2 of formula (3) above can be used as the first indicator. The sign of DEL2 is theoretically reversed whether the swapping is as shown in Figure 4 or as shown in Figure 5. Therefore, by combining DEL2 with an indicator that is theoretically not changed by the swapping of mounting positions, it is possible to detect the swapping of mounting positions. However, from the viewpoint of improving detection accuracy, DEL1 or DEL3, which have less variation, are preferred as indicators.

[0055] (3) The first index (or second index) used to compare the rotational speed of the tire mounted on the left front position FL and the tire mounted on the right rear position RR with the rotational speed of the tire mounted on the right front position FR and the tire mounted on the left rear position RL is not limited to the one defined in equation (1), but for example, DEL1 obtained by appropriately modifying equation (1) as follows, or DEL1 defined in equation (4), etc., can be used. DEL1=(V FL +V RR ) / (V FR +V RL ) DEL1=[(V FL +V RR )-(V FR +V RL )] (4)

[0056] (4) The first index used to compare the rotational speed of the tire mounted on the left front position FL and the tire mounted on the right front position FR with the rotational speed of the tire mounted on the left rear position RL and the tire mounted on the right rear position RR is not limited to DEL2 in equation (3), but can also be used, for example, DEL2 obtained by appropriately modifying equation (3) as shown below, or DEL2 as defined in equation (5). DEL2=(V FL +V FR ) / (V RL +V RR ) DEL2=[(V FL +V FR )-(V RL +VRR )] (5)

[0057] (5) The first index (or second index) used to compare the rotational speed of the tire mounted on the left front position FL and the tire mounted on the left rear position RL with the rotational speed of the tire mounted on the right front position FR and the tire mounted on the right rear position RR is not limited to the one defined in equation (2), but for example, DEL3 obtained by appropriately modifying equation (1) as follows, or DEL3 defined in equation (6), etc., can be used. DEL3=(V FL +V RL ) / (V FR +V RR ) DEL3=[(V FL +V RL )-(V FR +V RR )] (6)

[0058] (6) In the above embodiment, the torsional resonance frequencies of the tires included in the tire-wheel assembly mounted on the front axle were identified as the first torsional resonance frequency and the second torsional resonance frequency, respectively. However, the torsional resonance frequencies of the tires included in the tire-wheel assembly mounted on the rear axle may also be identified as the first torsional resonance frequency and the second torsional resonance frequency. From the viewpoint of accuracy in identifying the torsional resonance frequency, it is preferable to identify the torsional resonance frequency of the tire included in the tire-wheel assembly mounted on the axle with the greater load in vehicle 1.

[0059] (7) In the above embodiment, in order to distinguish between swapping mounting positions and reducing pressure on two wheels, in step S10, the swap determination unit 24 is Δω FL We compare this with the third threshold Th3, and Δω FR This was compared with the fourth threshold Th4. In addition to or instead of this, the replacement determination unit 24 determines the first torsional resonance frequency ω FL and the second torsional resonance frequency ω FRThe absolute value of the difference between the two values ​​may be compared with a predetermined threshold. The swapping determination unit 24 may determine that a swap of mounting positions has occurred (YES) if the absolute value is less than or equal to the predetermined threshold.

[0060] (8) Steps S5 and S10 may be omitted. That is, the specific part 23 may be omitted.

[0061] (9) Each step of the tire position swap detection process according to the above embodiment may be performed by multiple computers. That is, at least some of steps S1 to S13 may be performed by other external computers connected to the detection device 2. Also, the order in which steps S3 to S5 are performed may be changed. Furthermore, step S12 may be performed before step S11, and if it is determined that the initialization operation has already been accepted, the notification unit 25 may refrain from issuing a notification. [Explanation of Symbols]

[0062] 1 vehicle 2. Detection device 15 Storage device 20 Acquisition Department 21 First Calculation Unit 22 Second Calculation Unit 23 Specific section 24 Replacement Determination Unit 25 Notification Department 26 Initialization section

Claims

1. An acquisition unit that acquires the rotational speed of each tire mounted at the front left position, front right position, rear left position, and rear right position while the vehicle is in motion, the vehicle has at least the front left position, front right position, rear left position, and rear right position where tires are mounted. A first calculation unit that calculates a first index for comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position, or a first index for comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second calculation unit calculates a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. A replacement determination unit that determines whether or not the mounting position of the tires was changed before the vehicle was driven, based on the first and second indicators. Equipped with, The swapping determination unit determines that, if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then the swapping of the tires between the left front position and the left rear position occurred before the vehicle was driven, and the swapping of the tires between the right front position and the right rear position occurred before the vehicle was driven. Tire position swap detection device.

2. An acquisition unit that acquires the rotational speed of each tire mounted at the front left position, front right position, rear left position, and rear right position while the vehicle is in motion, the vehicle has at least the front left position, front right position, rear left position, and rear right position where tires are mounted. A first calculation unit that calculates a first index for comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position, or a first index for comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second calculation unit calculates a second index by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. A replacement determination unit that determines whether or not the mounting position of the tires was changed before the vehicle was driven, based on the first and second indicators. Equipped with, The swapping determination unit determines that, if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then the swapping of the tires between the left front position and the right rear position occurred before the vehicle was driven, and the swapping of the tires between the right front position and the left rear position occurred before the vehicle was driven. Tire position swap detection device.

3. Based on the rotational speed signals representing the rotational speed of each of the aforementioned tires, a specific unit identifies the first torsional resonance frequency of the tire mounted at the left front position and the second torsional resonance frequency of the tire mounted at the right front position, or identifies the first torsional resonance frequency of the tire mounted at the left rear position and the second torsional resonance frequency of the tire mounted at the right rear position based on the rotational speed of each of the aforementioned tires. Furthermore, The replacement determination unit determines that the tire replacement occurred before the vehicle was driven if the change from the initial value of the first indicator exceeds a predetermined first threshold, the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, the change from the initial value of the first torsional resonance frequency is less than or equal to a predetermined third threshold, and the change from the initial value of the second torsional resonance frequency is less than or equal to a predetermined fourth threshold. The tire position swapping detection device according to claim 1 or 2.

4. If it is determined that the aforementioned tire change occurred before the vehicle was driven, a notification unit will generate a notification prompting the vehicle user to perform an initialization operation. Furthermore, The tire position swapping detection device according to claim 1 or 2.

5. A tire position swap detection method performed by one or more computers, The rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions is obtained while the vehicle is in motion, and the vehicle has at least the front left, front right, rear left, and rear right positions on which tires are mounted. To calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position, or to calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second index is calculated by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. Based on the first and second indicators, it is determined whether or not the mounting position of the tires was changed before the vehicle was driven. Equipped with, The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the left rear position before the vehicle was driven, and that the tires were swapped between the right front position and the right rear position before the vehicle was driven. Method for detecting tire position swap.

6. A tire position swap detection method performed by one or more computers, The rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions is obtained while the vehicle is in motion, and the vehicle has at least the front left, front right, rear left, and rear right positions on which tires are mounted. To calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position, or to calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second index is calculated by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. Based on the first and second indicators, it is determined whether or not the mounting position of the tires was changed before the vehicle was driven. Equipped with, The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the right rear position before the vehicle was driven, and that the tires were swapped between the right front position and the left rear position before the vehicle was driven. Method for detecting tire position swap.

7. The rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions is obtained while the vehicle is in motion, and the vehicle has at least the front left, front right, rear left, and rear right positions on which tires are mounted. To calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position, or to calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second index is calculated by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position. Based on the first and second indicators, it is determined whether or not the mounting position of the tires was changed before the vehicle was driven. Run this on one or more computers, The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the left rear position before the vehicle was driven, and that the tires were swapped between the right front position and the right rear position before the vehicle was driven. Tire position swap detection program.

8. The rotational speed of each tire mounted at the front left, front right, rear left, and rear right positions is obtained while the vehicle is in motion, and the vehicle has at least the front left, front right, rear left, and rear right positions on which tires are mounted. To calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear left position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear right position, or to calculate a first index that compares the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the front right position with the rotational speed of the tire mounted at the rear left position and the rotational speed of the tire mounted at the rear right position, A second index is calculated by comparing the rotational speed of the tire mounted at the front left position and the rotational speed of the tire mounted at the rear right position with the rotational speed of the tire mounted at the front right position and the rotational speed of the tire mounted at the rear left position. Based on the first and second indicators, it is determined whether or not the mounting position of the tires was changed before the vehicle was driven. Run this on one or more computers, The determination described above is made if the change from the initial value of the first indicator exceeds a predetermined first threshold, and the change from the initial value of the second indicator is less than or equal to a predetermined second threshold, then it is determined that the tires were swapped between the left front position and the right rear position before the vehicle was driven, and that the tires were swapped between the right front position and the left rear position before the vehicle was driven. Tire position swap detection program.

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