Wheel condition acquisition system and wheel condition acquisition method

Abstract

To properly acquire information representing whether wheel condition is abnormal or not.SOLUTION: A wheel condition acquisition system comprises the steps of: acquiring wheel speed difference between at least two wheels among a plurality of wheels based on respective wheel speeds of the plurality of wheels which are detected when travelling state of a vehicle is a setting state; and acquiring whether at least one wheel of the plurality of wheels is in an abnormal condition or not based on the wheel speed difference. Since it is based on respective wheel speeds of the plurality of wheels detected when travelling state of the vehicle is the setting state, it is properly acquired whether at least one wheel is in the abnormal condition or not.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a wheel condition acquisition system for acquiring the condition of a wheel of a vehicle. [Background technology]

[0002] In the wheel condition acquisition system described in Patent Document 1, a first detection signal and a second detection signal are acquired based on the difference between the detection value of the wheel speed sensor and a reference value, and if at least one of the first detection signal and the second detection signal is greater than a detection threshold, the wheel is determined to be in a loose state. It also states that the detection value of the wheel speed sensor of another wheel can be used as the reference value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 06526818 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] The object of the present invention is to The wheel is loosely fastened to the body The purpose of the present invention is to appropriately acquire whether or not an abnormal state exists.

[0005] In the wheel state acquisition system according to the present invention, a wheel speed difference between two wheels among the plurality of wheels is acquired based on the wheel speeds of the plurality of wheels detected when the vehicle is in a set running state, and whether at least one wheel among the plurality of wheels is in an abnormal state is acquired based on the wheel speed difference between the two wheels.

[0006] For example, the abnormal state can be a state in which the hub bolt, hub nut, etc. that rotatably holds the wheel to the vehicle body member is loosened, causing the wheel to be loosened from the vehicle body member. In a state in which the hub bolt, hub nut, etc. is loose (hereinafter sometimes referred to as a loose state), the wheel speed changes significantly during one rotation of the wheel due to the looseness of the hub bolt, hub nut, etc., and the wheel speed difference between the two wheels changes significantly. Furthermore, for example, the set state can be a state in which external forces acting on the wheels are small. When the vehicle is in the set state, changes in wheel speed due to external forces caused by wheel rotation are suppressed. Therefore, based on the wheel speeds of the multiple wheels detected when the vehicle is in the set state, it is possible to appropriately obtain changes in wheel speed due to loosening of hub bolts, hub nuts, etc. As described above, in the wheel state acquisition system according to the present invention, since the wheel speed is detected when the vehicle's running state is in a set state, it is possible to appropriately acquire whether or not at least one wheel is in a loose state. The wheel state can also be acquired using a model previously obtained by machine learning. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram conceptually illustrating a wheel state acquisition system according to a first embodiment of the present invention. [Figure 2] 4 is a flowchart showing the execution (acquisition of the wheel state) of the wheel state acquisition system. [Figure 3] 4 is a flowchart showing a wheel speed difference acquisition program stored in the wheel state acquisition system. [Figure 4] 4 is a flowchart showing a looseness determination program stored in the wheel state acquisition system. [Figure 5](A) and (B) are graphs showing the relationship between the wheel speed difference and the steering angle for the left and right front wheels and the left and right rear wheels of the vehicle. (C) and (D) are graphs showing the relationship between the wheel speed difference and the longitudinal acceleration for the left and right front and rear wheels of the vehicle. [Figure 6] 10A and 10B are diagrams showing the relationship between the vehicle body lateral acceleration and the steering angle when the wheels are in a normal state and when the wheels are in a loose state, respectively, in a vehicle equipped with a wheel state acquisition system according to a second embodiment of the present invention. [Figure 7] 4 is a flowchart showing a looseness determination program stored in the wheel state acquisition system. [Figure 8] 4 is a flowchart conceptually showing the execution (acquisition of the wheel state) of the wheel state acquisition system. [Figure 9] 10 is a flowchart conceptually showing the execution (acquisition of the wheel state) of a wheel state acquisition system according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a diagram conceptually illustrating a trained model included in a wheel state acquisition system according to a fourth embodiment of the present invention. [Figure 11] 5 is a flowchart showing a loosening determination program different from the flowchart of FIG. 4. Embodiments of the invention

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wheel state acquisition system according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Example 1

[0009] The wheel state acquisition system according to this embodiment includes wheel speed sensors 12FL, 12FR, 12RL, and 12RR, a steering angle sensor 14, a longitudinal acceleration sensor 16, a vehicle body lateral acceleration sensor 18, an ECU 20 mainly composed of a computer, and a server 26. In this embodiment, the left and right front wheels 10FL and 10FR are drive wheels and steered wheels.

[0010] The wheel speed sensors 12FL, 12FR, 12RL, and 12RR detect the wheel speeds of the left front wheel 10FL, right front wheel 10FR, left rear wheel 10RL, and right rear wheel 10RR, respectively, which are located on the front, rear, left, and right sides of the vehicle. In this embodiment, the steering angle sensor 14 detects the steering angle of the left and right front wheels 10FL, 10FR, which are steered wheels. Depending on the direction of steering of the steered wheels, the steering angle may be a positive value or a negative value. Note that instead of the steering angle sensor, an operation amount sensor may be used that detects the operation amount (which may be a steering angle) as the operation state of a steering operation member (not shown). The longitudinal acceleration sensor 16 detects acceleration applied to the vehicle in the longitudinal direction. The acceleration may be a positive value or a negative value. Negative acceleration may be referred to as deceleration. The vehicle body lateral acceleration sensor 18 detects the vehicle body lateral acceleration, which is the acceleration acting on the vehicle body in the lateral direction, and is an example of a vehicle body lateral acceleration detection unit.

[0011] In this embodiment, the wheel speed sensors 12FL, 12FR, 12RL, 12RR, etc. constitute a wheel speed detection unit, and the steering angle sensor 14, the longitudinal acceleration sensor 16, etc. constitute a running condition detection unit. The running condition detection unit may include the wheel speed sensors 12FL, 12FR, 12RL, 12RR and the vehicle body lateral acceleration sensor 18.

[0012] The ECU 20 includes an execution unit, a storage unit, an input / output unit, etc. The input / output unit is connected to the wheel speed sensors 12FL, 12FR, 12RL, 12RR, the steering angle sensor 14, the longitudinal acceleration sensor 16, the vehicle body lateral acceleration sensor 18, etc., as well as to a display 22, a communication device 24, etc. A cloud computer 26 serving as a server is connected to the communication device 24. The cloud computer 26 is provided with external communication means 28 capable of communicating with the outside. Hereinafter, in this specification, when there is no need to distinguish between wheel positions for wheel speed sensors, wheel speeds, wheel speed differences, etc., or when they are referred to collectively, the letters FL, FR, RL, RR, f, r, L, R, etc., which represent wheel positions, may be omitted.

[0013] The ECU 20 is provided with a setting state acquisition unit 30, a wheel speed difference acquisition unit 32, an abnormal state acquisition unit 34, and the like. The set state acquisition unit 30 acquires whether the vehicle running state detected by the running state detection unit is in a predetermined set state. The set state is a state suitable for determining whether the wheel 10 is in an abnormal state, and refers to a state in which an external force applied to the wheel 10 is small. The set state can be, for example, at least one of a state in which the absolute value of the steering angle of the steered wheel detected by the steering angle sensor 14 is smaller than a set steering angle, and a state in which the absolute value of the longitudinal acceleration detected by the longitudinal acceleration sensor 16 is smaller than a set acceleration. The set state can also be at least one of a state in which the vehicle is running approximately straight ahead and a state in which the vehicle is running at an approximately constant speed.

[0014] When the setting state acquisition unit 30 acquires that the vehicle's running state is in the setting state, the wheel speed difference acquisition unit 32 acquires the wheel speed difference δf between the front left and right wheels 10FL, 10FR, the wheel speed difference δr between the rear left and right wheels 10RL, 10RR, the wheel speed difference δL between the left front and rear wheels 10FL, 10RL, and the wheel speed difference δR between the right front and rear wheels 10FR, 10RR, based on the wheel speeds of the front, rear, left, and right wheels 10 detected by the wheel speed sensors 12. The wheel speed sensors 12 detect a plurality of wheel speeds for each of the front, rear, left, and right wheels 10, and acquire a plurality of the wheel speed differences δf, δr, δL, and δR based on the detected wheel speeds for each of the plurality of wheels.

[0015] The abnormal state acquisition unit 34 acquires a variation value representing the variation of each of the wheel speed differences δf, δr, δL, δR, etc., based on the multiple wheel speed differences δf, δr, δL, δR, etc. acquired by the wheel speed difference acquisition unit 32, and determines whether at least one of the four wheels 10 is in an abnormal state based on these variation values. In this embodiment, the abnormal state refers to a state in which a hub bolt, a hub nut, etc., that rotatably holds the wheel 10 to a vehicle body member is loosened, causing the wheel 10 to be loosely fastened to the vehicle body member. This state may also be simply referred to as a loose state or a loosened state. Furthermore, the wheel speed sensor 12 detects multiple wheel speeds, and the number of detected wheel speeds can be set to a number that allows a variation value to be acquired.

[0016] In the wheel state acquisition system configured as above, a wheel state acquisition program shown in the flowchart of FIG. 2 is executed at predetermined intervals. In step 1 (hereinafter abbreviated as S1, the same applies to other steps), the longitudinal acceleration detected by the longitudinal acceleration sensor 16, the steering angle θ detected by the steering angle sensor 14, etc. are acquired.

[0017] In S2, the vehicle running state is acquired based on the longitudinal acceleration, steering angle θ, etc., and it is determined whether the vehicle running state is in a set state. If the determination in S2 is YES, in S3, multiple wheel speed differences δf, δr, δL, δR are acquired as described below, and in S4 and S5, it is determined whether at least one of the front, rear, left, and right wheels 10 is in a loose state.

[0018] If the determination in S5 is YES, in S6, this is notified to the occupant by, for example, displaying it on the display 22. In S7, a looseness determination flag is sent to the cloud computer 26. The looseness determination flag is supplied from the ECU 20 to the communication device 24, and the communication device 24 transmits it to the cloud computer 26. In S8, the cloud computer 26 notifies the vehicle manager (e.g., a shared car operator), vehicle operation company (e.g., a vehicle maintenance company), etc. (hereinafter referred to as the vehicle manager, etc.) of this via external communication means 28. The vehicle manager, etc. is notified by, for example, external communication means 28, such as email, a dedicated app, a network system, or telephone.

[0019] The wheel speed differences Δf, Δr, ΔL, and ΔR in S3 are acquired by the wheel speed difference acquisition unit 32 of the vehicle's ECU 20. In this embodiment, a wheel speed difference acquisition program shown in the flowchart of Fig. 3 is repeatedly executed at set time intervals. In S11, the wheel speed sensors 12 detect the wheel speeds of the wheels 10 located on the front, rear, left and right sides, and in S12, wheel speed differences Δf, Δr, ΔL, ΔR are obtained and stored in S13. S11 to S13 are repeatedly executed, and a plurality of wheel speed differences Δf, Δr, ΔL, ΔR are obtained and stored for each. In this embodiment, a plurality of wheel speed differences δ are acquired, and the number of wheel speed differences δ to be acquired is set to a number that allows a standard deviation as a variation value to be obtained satisfactorily.

[0020] In this embodiment, the wheel speed difference δf is (WFR-WFL) / WFL, which is the value obtained by dividing the wheel speed difference (WFR-WFL) between the left and right front wheels 10FL, 10FR by the wheel speed WFL of the left front wheel 10FL. The wheel speed difference δr is (WRR-WRL) / WRL, which is the value obtained by dividing the wheel speed difference (WRR-WRL) between the left and right rear wheels 10RL, 10RR by the wheel speed WRL of the left rear wheel 10RL. The wheel speed difference δL is (WFL-WRL) / WRL, which is the value obtained by dividing the wheel speed difference (WFL-WRL) between the left front and rear wheels 10FL, 10RL by the wheel speed WRL of the left rear wheel 10RL. The wheel speed difference δR is (WFR-WRR) between the right front and rear wheels 10FR, 10RR by the wheel speed WFL of the right rear wheel 10RR. Wheel speed WRR The value is (WFR-WRR) / WRR divided by

[0021] In this way, for example, by dividing the difference in wheel speed between the left and right wheels 10FL, 10FR (WFR-WFL) by the wheel speed WFL of the left front wheel 10FL, the influence of the magnitude of the wheel speed on the difference in wheel speed can be reduced.

[0022] An example of wheel speed differences δf, δr, δL, δR for two wheels 10 is shown in FIGS. 5A-5D. Figure 5A shows the change in wheel speed difference δf {(WFR-WFL) / WFL} with changes in steering angle θ. When steering angle θ is approximately 0, the value obtained by subtracting wheel speed WFL of left front wheel 10FL from wheel speed WFR of right front wheel 10FR should be small. Furthermore, as the absolute value of steering angle θ increases, the difference between the rotational speed of the outer wheel and the rotational speed of the inner wheel increases, and the absolute value of wheel speed difference δf also increases. The solid line LA in Figure 5A shows the average value of wheel speed difference δf. As the solid line LA shows, as steering angle θ increases, the average value of wheel speed difference δf increases.

[0023] On the other hand, the wheel speed detected during one rotation of the wheel 10 is not always constant and may change depending on the state of the wheel 10. Therefore, the difference between the wheel speed WFR of the right front wheel 10FR and the wheel speed WFL of the left front wheel 10FL is also not always constant and varies. However, when the wheel 10 is in a normal state, the change in wheel speed during one rotation of the wheel 10 is small. Therefore, when the right front wheel 10FR and the left front wheel 10FL are in a normal state, the wheel speed difference Δf between the right front wheel 10FR and the left front wheel 10FL is small, and the variation is usually small. In FIG. 5A, the length of arrow A indicates twice the standard deviation ef (2ef), which is a variation value that represents the variation in the wheel speed difference Δf. As shown in FIG. 5A, when the right front wheel 10FR and the left front wheel 10FL are in a normal state (not in a loose state), the standard deviation ef is small.

[0024] FIG. 5B shows the change in the wheel speed difference δr{(WRR−WRL) / WRL} with respect to the change in the steering angle θ. The average value of the wheel speed difference δr indicated by the solid line LB increases as the steering angle θ increases, as in the case shown in Figure 5A. However, because the left rear wheel 10RL is in a loose state, the wheel speed WRL of the left rear wheel 10RL changes significantly over one rotation, resulting in a large variation in the wheel speed difference δr. As a result, the standard deviation er, which is the length of arrow B in Figure 5B, increases by twice (2er).

[0025] FIG. 5C shows the change in wheel speed difference ΔL{(WFL−WRL) / WRL} with respect to the change in longitudinal acceleration Gx. As shown by the solid line LC representing the average value of the wheel speed difference δL, when the longitudinal acceleration Gx is approximately 0, the difference between the wheel speed of the left front wheel 10FL and the wheel speed of the left rear wheel 10RL is small. When the longitudinal acceleration Gx increases (positive acceleration increases), a driving force is applied to the left front wheel 10FL, which is the drive wheel, causing the wheel speed of the left front wheel 10FL to increase, but the wheel speed of the left rear wheel 10RL increases with a delay. Therefore, the average value of the wheel speed difference δL increases as the longitudinal acceleration Gx decreases. When the longitudinal acceleration Gx decreases (deceleration acts), the vehicle takes a nose dive attitude, and because a drive source is connected to the left front wheel 10FL, the wheel speed of the left front wheel 10FL decreases more quickly than that of the left rear wheel 10RL. Therefore, the average value of the wheel speed difference δL decreases as the longitudinal acceleration Gx decreases (deceleration increases).

[0026] Furthermore, since the left rear wheel 10RL is in a loose state, the wheel speed difference ΔL varies widely as indicated by arrow C, and the standard deviation eL also increases.

[0027] FIG. 5D shows the change in wheel speed difference ΔR{(WFR−WRR) / WRR} with respect to the change in longitudinal acceleration Gx. Similar to the case shown in FIG. 5C, the average value of the wheel speed difference ΔR increases with an increase in the longitudinal acceleration Gx, as indicated by the solid line LD. Further, since the front right wheel 10FR and the rear right wheel 10RR are in a normal state (not loose), as indicated by the arrow D, the standard deviation eR of the wheel speed difference ΔR is small.

[0028] The looseness determination in S4 is performed by the abnormality state acquisition unit 34 of the vehicle's ECU 20. By executing the looseness determination routine shown in the flowchart of Fig. 4, it is determined whether at least one wheel 10 is in a loose state based on the multiple wheel speed differences δf, δr, δL, and δR acquired by the wheel speed difference acquisition unit 32. In this embodiment, standard deviations ef, er, eL, eR are obtained as the variation values ​​of the wheel speed differences δf, δr, δL, δR based on multiple wheel speed differences δf, δr, δL, δR, and whether at least one wheel 10 is in a loose state is determined based on the ratio of these standard deviations ef, er, eL, eR.

[0029] When the vehicle is in a state where the absolute value of the steering angle θ is smaller than the set steering angle, the ratio γ of the standard deviation ef of the wheel speed difference δf between the front left and right wheels 10FL, 10FR and the standard deviation er of the wheel speed difference δr between the rear left and right wheels 10FR, 10RR is obtained. γ=er / ef

[0030] When the vehicle is traveling in a state where the absolute value of the steering angle θ is smaller than the set steering angle, for example, if both the left and right front wheels are in a normal state, the variation in the wheel speed difference δf between the left and right wheels will be small, and the standard deviation ef will also be small. On the other hand, if, for example, one of the left and right rear wheels is in a loose state, the wheel speed difference δr between the left and right wheels will vary greatly, and the standard deviation er will be large. Therefore, based on the ratio γ of these standard deviations ef and er, it is possible to appropriately determine whether or not a wheel is in a loose state.

[0031] On the other hand, if the absolute value of the steering angle θ is greater than the set steering angle, the wheel speed during one rotation of the wheel 10 may change due to external forces, such as an increase in the lateral friction force acting between the wheel 10 and the road surface. On the other hand, when the absolute value of the steering angle θ is smaller than the set steering angle, the change in wheel speed due to external force is small, so it is possible to properly obtain the change in wheel speed due to loosening of the fastening of the wheel 10 to the vehicle body member.

[0032] When the ratio γ is greater than a first set ratio γ1 that is greater than 1 (γ>γ1>1), it is determined that at least one of the rear left and right wheels 10RL, 10RR is in a loose state. When the ratio γ is smaller than a second set ratio γ2 that is smaller than 1 (γ<γ2<1), it is determined that at least one of the front left and right wheels 10FL, 10FR is in a loose state.

[0033] When the vehicle is traveling in a state in which the absolute value of the longitudinal acceleration Gx is smaller than the set acceleration, the ratio β of the standard deviation eL of the wheel speed difference δL for the left front and rear wheels 10FL, 10RL to the standard deviation eR of the wheel speed difference δR for the right front and rear wheels 10FR, 10RR is obtained. β=eL / eR

[0034] When the vehicle is running in a state where the absolute value of the longitudinal acceleration Gx is smaller than the set acceleration, for example, if both the front and rear wheels on the right side are in a normal state, the variation in the wheel speed difference δR between the front and rear wheels will be small, and the standard deviation eR will also be small. On the other hand, if at least one of the front and rear wheels on the left side is in a loose state, the variation in the wheel speed difference δL between the front and rear wheels will be large, and the standard deviation e L becomes larger. Therefore, based on the ratio β of the standard deviations eL, eR of the wheel speed differences δL, δR, it is possible to appropriately determine whether the change in wheel speed during one rotation of the wheel is large.

[0035] On the other hand, if the absolute value of the longitudinal acceleration Gx is greater than the set acceleration, the wheel speed during one rotation of the wheel 10 may change due to external forces, such as an increase in the longitudinal friction force acting between the wheel 10 and the road surface. On the other hand, when the absolute value of the longitudinal acceleration Gx is smaller than the set acceleration, the change in wheel speed due to external forces becomes small, making it possible to properly obtain the change in wheel speed due to loosening of the fastening state of the wheel 10 to the vehicle body side member.

[0036] If the ratio β is greater than a third set ratio β3 that is greater than 1 (β>β3>1), it is determined that at least one of the left front and rear wheels 10FL, 10RL is in a loose state. When the ratio β is smaller than a fourth set ratio β4 that is smaller than 1 (β<β4<1), it is determined that at least one of the right front and rear wheels 10RL, 10RR is in a loose state.

[0037] The loosening determination program shown in the flowchart of FIG. 4 is executed at set intervals. In S20, it is determined whether the vehicle is in a state where the absolute value of the steering angle θ is smaller than the set steering angle (which can be considered to be a state of approximately straight driving). If the determination is YES, in S21, the ratio γ is acquired, and in S22, the ratio γ is compared with the first setting ratioIn step S22, it is determined whether the ratio γ is greater than γ1, and in step S23, it is determined whether the ratio γ is smaller than a second set ratio γ2. If the determination in step S22 is YES, in step S24, rear Left and right wheels 10 RL ,10 RR If the determination in S22 is NO and the determination in S23 is YES, then in S25, before Left and right wheels 10 FL ,10 FR It is determined that at least one of the above is loose.

[0038] If the determination in S20 is NO, S25a and subsequent steps are executed. In S25a, it is determined whether the vehicle is running in a state in which the absolute value of the longitudinal acceleration Gx is smaller than the set acceleration. If the determination is YES, in S26, the ratio β is acquired, in S27, it is determined whether the ratio β is larger than a third set ratio β3, and in S28, it is determined whether the ratio β is smaller than a fourth set ratio β4. If the determination in S27 is YES, in S29, it is determined that at least one of the left front and rear wheels 10FL, 10RL is in a loose state. If the determination in S27 is NO and the determination in S28 is YES, it is determined in S30 that at least one of the right front and rear wheels 10FR, 10RR is in a loose state. Based on the result of this determination, steps S6 to S8 are executed.

[0039] As described above, in this embodiment, when the vehicle is traveling in the set state, the wheel speed sensor 12 detects a plurality of wheel speeds for each of the front, rear, left, and right wheels 10. Then, based on these wheel speeds W, a plurality of wheel speed differences δf between the front left and right wheels 10FL, 10FR, a wheel speed difference δr between the rear left and right wheels 10RL, 10RR, a wheel speed difference δL between the left front and rear wheels 10FL, 10RL, and a wheel speed difference δR between the right front and rear wheels 10FR, 10RR are obtained, and the standard deviations ef, er, eL, and eR are obtained, respectively. Then, the ratio γ of these standard deviations is calculated. (er / ef), the ratio β(eL / eR) is obtained, and based on these ratios γ and β, it is determined whether at least one wheel 10 is in a loose state, and the position of the wheel 10 in the loose state is obtained. For example, if it is determined that at least one wheel 10 of the rear left and right wheels 10RL, 10RR and at least one wheel 10 of the left front and rear wheels 10FL, 10RL is in a loose state, it can be determined that the wheel in the loose state is the left rear wheel 10RL.

[0040] In this case, when the vehicle is traveling in a set state, the wheel speed W is detected, and the wheel speed difference δ and standard deviation e are obtained based on the wheel speeds W, and it is determined whether the wheel 10 is in a loose state. In this way, since it is based on the wheel speed W detected when the external force acting on the wheel 10 is small, it is possible to appropriately determine whether the wheel 10 is in a loose state.

[0041] Furthermore, since it is based on the ratio of the standard deviation e as a variation value of the wheel speed difference δ, the tendency of the magnitude of change in the wheel speed W can be accurately obtained, and it can be appropriately determined whether the wheel 10 is in a loose state.

[0042] Furthermore, the fact that the wheel 10 is in a loose state is notified not only to the vehicle occupants but also to the vehicle manager and the operation management company, so that the vehicle manager and the operation management company can be made aware of the safety of the vehicle.

[0043] In addition, in the wheel state acquisition system described in Patent Document 1, the detected values ​​of the wheel speed sensors are corrected for defects in the wheel speed sensors, and thus the detected values ​​of each tooth of the wheel speed sensors are acquired. Therefore, a processing device mainly composed of a computer is used frequently. In contrast, in the wheel state acquisition system described in this embodiment, it is determined whether at least one wheel 10 is in an abnormal state based on the variation value of the wheel speed difference δ between the two wheels 10. Therefore, it is not essential to acquire the detection value of each tooth of the wheel speed sensor 12, and it is possible to reduce the frequency of use of the ECU 20 when acquiring the wheel state.

[0044] Furthermore, in the wheel state acquisition system described in this embodiment, since the wheel state acquisition is based on the wheel speed detected when the vehicle's running state is in a set state, it is possible to reduce the frequency of use of ECU 20 compared to when the wheel speed is detected all the time.

[0045] Furthermore, for example, if the tire air pressure of a wheel 10 drops, the radius of the wheel 10 decreases, and the wheel speed W decreases. Therefore, the average value of the wheel speed difference between the two wheels 10 including that wheel 10 increases. However, this does not mean that the variation in the wheel speed difference between the two wheels 10 increases. Therefore, in this embodiment, it is possible to appropriately determine whether the wheel 10 is in a loose state rather than a state where the tire air pressure has dropped.

[0046] In the above embodiment, the standard deviation e is used as a variation value of the wheel speed difference δ, but it is not limited to the standard deviation e, and other values ​​such as a variance, a maximum-minimum value, or an interquartile range can also be used. The interquartile range is the difference between the first and third quartiles, and the first and third quartiles refer to the values ​​(25%, 75%) obtained by dividing the data into four equal parts when the data is sorted in order of size. In any case, the value increases as the variation in the wheel speed difference δ increases.

[0047] In the above embodiment, the set state of the vehicle's driving state is at least one of a substantially straight-line driving state and a substantially constant-speed driving state. However, the set state may also be a state that changes between a straight-line driving state and a turning state, or a state that changes between a constant-speed driving state and an accelerating / decelerating state. For example, when the external force applied to the wheel 10 changes, such as when the vehicle changes between a straight-line driving state and a turning state, or when the vehicle changes between a constant-speed driving state and an accelerating / decelerating state, the hub bolts, nuts, etc. may become misaligned, resulting in a significant change in wheel speed. Meanwhile, during transitional periods when these states change, it may be difficult to obtain a sufficient number of wheel speeds to obtain a variation value. In such cases, the wheel speeds obtained during multiple transitional periods may be combined to obtain a variation value of the wheel speed difference.

[0048] Furthermore, when turning, the wheel speed differences δf, δr between the left and right wheels become large, and when accelerating and decelerating, the wheel speed differences δL, δR between the front and rear wheels become large. Therefore, it is desirable to obtain the variation value by correcting these speed differences based on the steering angle θ of the steering wheels of the vehicle, the longitudinal acceleration Gx applied to the vehicle, etc.

[0049] Furthermore, it is not essential to determine that at least one of the four wheels 10 is in an abnormal state when the ratio of the variation values ​​of the wheel speed differences between the two wheels 10 in each of two wheel pairs is outside a set range, as in the above embodiment. For example, it is possible to determine that at least one of the two wheels 10 is in an abnormal state when the standard deviation e as the variation value of the wheel speed difference δ between the two wheels 10 is greater than a predetermined threshold eth.

[0050] An example of this will be described based on the looseness determination program shown in the flow chart of FIG. In S121, it is determined whether the absolute value of the steering angle θ of the steered wheels is smaller than the set steering angle. If the determination is YES, in S122 and S123, it is determined whether the standard deviation ef of the wheel speed difference δf between the left and right front wheels is larger than a threshold value efth, and whether the standard deviation er of the wheel speed difference δr between the left and right rear wheels is larger than a threshold value erth. If the determination is YES in S122, it is determined in S124 that at least one wheel 10 of the left and right front wheels 10FL, 10FR is in an abnormal state. If the determination is YES in S123, it is determined in S125 that at least one wheel 10 of the left and right rear wheels 10RL, 10RR is in an abnormal state.

[0051] In S126, it is determined whether the absolute value of the longitudinal acceleration is smaller than a set acceleration. If the determination is YES, in S127 and S128, it is determined whether the standard deviation eL of the wheel speed difference δL between the front and rear wheels on the left side is larger than a threshold value eLth, and whether the standard deviation eR of the wheel speed difference δR between the front and rear wheels on the right side is larger than a threshold value eRth. If the determination is YES in S127, it is determined in S129 that at least one wheel 10 of the front and rear wheels 10FL, 10RL on the left side is in an abnormal state. If the determination is YES in S128, it is determined in S130 that at least one wheel 10 of the front and rear wheels 10FR, 10RR on the right side is in an abnormal state.

[0052] As described above, in this embodiment, the setting state acquisition unit is constituted by the part that executes and stores S2 of the wheel state acquisition program shown in the flowchart of Figure 2 of ECU 20, the wheel speed difference acquisition unit is constituted by the part that stores and executes S3 (the wheel speed difference acquisition program shown in the flowchart of Figure 3), and the abnormal state acquisition unit is constituted by the part that stores and executes S4, 5 (the looseness determination program shown in the flowchart of Figure 4 or Figure 11). Furthermore, the execution of S2 corresponds to a setting state acquisition step, the execution of S3 corresponds to a wheel speed difference acquisition step, and the execution of S4 and S5 corresponds to an abnormal state acquisition step. Example 2

[0053] In the above embodiment, the wheel state is obtained based on the ratio of the variation values ​​of the wheel speed difference δ, but the wheel state can also be obtained based on both the ratio of the variation values ​​of the wheel speed difference δ and the variation value of the vehicle body lateral acceleration Gy.

[0054] An example of changes in vehicle body lateral acceleration is shown in Figures 6A and 6B. As shown in Figures 6A and 6B, when the vehicle is traveling approximately straight and the wheels 10 are in a normal state, vibrations occurring in the vehicle body due to changes in the wheel speed of the wheels 10 are small. Therefore, as indicated by the length of arrow E in Figure 6A, when the four wheels 10 are in a normal state, the standard deviation e, which is a variation value of the vehicle body lateral acceleration Gy, is small.

[0055] In contrast, when at least one of the four wheels 10 is in a loose state, the wheel speed changes significantly during one rotation of the wheel 10. Therefore, as shown in Fig. 6B, the large change in wheel speed causes large lateral vibrations to be applied to the vehicle body. The lateral vibrations of the vehicle body cause large changes in the vehicle body lateral acceleration Gy, and as indicated by the length of arrow F, the variation in the vehicle body lateral acceleration Gy increases, increasing the standard deviation e.

[0056] Therefore, in this embodiment, the standard deviation ey0 of the vehicle body lateral acceleration Gy when the four wheels 10 are in a normal state is stored in advance, and the ratio α of the standard deviation ey* of the actual vehicle body lateral acceleration Gy to the standard deviation ey0 of the vehicle body lateral acceleration Gy when in a normal state is obtained. α=ey* / ey0 When the ratio α is greater than a fifth set ratio α5, which is a set ratio greater than 1 (α>α5>1), it is determined that at least one of the front, rear, left, and right wheels 10 is in a loose state.

[0057] In addition, notification can be made in different ways depending on whether it is determined that at least one wheel 10 is in a loose state based on the ratio of the variation values ​​of the wheel speed difference δ and also based on the variation value of the vehicle body lateral acceleration Gy, or whether it is determined that at least one wheel 10 is in a loose state based on either the ratio of the variation values ​​of the wheel speed difference δ or the variation value of the vehicle body lateral acceleration Gy.

[0058] For example, if it is determined that at least one wheel 10 is in a loose state based on the ratio of the variation values ​​of the wheel speed difference δ, and if it is determined that at least one wheel 10 is in a loose state based on the variation value of the vehicle lateral acceleration Gy, information indicating with a high degree of certainty that the wheel 10 is in a loose state is notified to both the occupant, the vehicle manager, the vehicle operator, etc. On the other hand, if it is determined that at least one wheel 10 is in a loose state based on either the ratio of the variation value of the wheel speed difference δ or the variation value of the vehicle lateral acceleration Gy, there is a possibility that the wheel 10 is in a loose state, but since the probability is low, information urging an inspection of the fastening state of the hub bolts, etc. is notified to the vehicle manager or vehicle operator, and it is possible to prevent direct notification to the occupants.

[0059] In this embodiment, looseness determination is performed by executing S4 and S5 of Figure 8 (looseness determination program represented by the flowchart of Figure 7), and notification of information representing the wheel state is performed by executing S6-8, S35 and S36 of the wheel state acquisition program represented by the flowchart of Figure 8. The same step numbers are used to indicate steps that are executed in the same way between the loosening determination program shown in the flowchart of Fig. 7 and the loosening determination program shown in the flowchart of Fig. 4, and the same step numbers are used to indicate steps that are executed in the same way between the wheel state acquisition program shown in the flowchart of Fig. 8 and the wheel state acquisition program shown in the flowchart of Fig. 2, and the same step numbers are used to indicate steps that are executed in the same way between the wheel state acquisition program shown in the flowchart of Fig. 8 and the wheel state acquisition program shown in the flowchart of Fig. 2, and the same step numbers are used to indicate steps that are executed in the same way between the wheel state acquisition program shown in the flowchart of Fig. 8 and the wheel state acquisition program shown in the flowchart of Fig. 2, and the same step numbers are used to indicate steps that are executed in the same way between the wheel state acquisition program shown in the flowchart of Fig. 7 and the wheel state acquisition program shown in the flowchart of Fig. 4, and the same step numbers are used to indicate steps that are executed in the same way between the wheel state acquisition program shown in the flowchart of Fig. 8 and the wheel state acquisition program shown in the flowchart of Fig. 2 ...

[0060] In the looseness determination program shown in the flowchart of Figure 7, in S20, it is determined whether the absolute value of the steering angle θ is smaller than the set steering angle. This is to determine whether the vehicle body is not experiencing lateral acceleration due to the turning of the vehicle. If the determination is NO, S42-46, S21-25 are not executed. If the determination in S20 is YES, then in S42, multiple detection values ​​of the vehicle body lateral acceleration sensor 18 are acquired, and in S43, the standard deviation ey* is acquired. Then, the acquired standard deviation ey* is divided by the standard deviation ey0 of the vehicle body lateral acceleration Gy when each of the front, rear, left, and right wheels 10 is in a normal state to obtain a ratio α(ey* / ey0), and in S44, it is determined whether the ratio α is greater than a fifth set ratio α5. If the determination is YES, then in S45, flag 1 is turned ON. If the determination is NO, then S45 is not executed.

[0061] Furthermore, if it is determined in steps S21 to S25 that at least one of the left and right wheels 10 on the front or rear side is in a loose state, flag 2 is turned ON in step S46. Furthermore, if it is determined in S25a to S30 that at least one of the front and rear wheels on the left or right side is in a loose state, flag 3 is set ON in S47.

[0062] 8, if it is determined in S5 that at least one wheel 10 is in a loose state, the states of flags 1 to 3 are obtained in S35 and S36. In S35, it is determined whether both flag 1 and (at least one of flag 2 and flag 3) are ON (for example, flags 1 and 2 are ON, flags 1 and 3 are ON, or flags 1, 2, and 3 are ON), and in S36 it is determined whether either flag 1 or (at least one of flag 2 and flag 3) is ON (for example, flag 1 is ON and flag 2 and flag 3 are OFF, or flag 1 is OFF and at least one of flag 2 and flag 3 is ON). If the determination in S35 is YES, S6, S7, and S8 are executed. In this embodiment, information indicating with high certainty that the wheel 10 is in a loose state is notified to the occupant, the vehicle manager, and the vehicle operation company.

[0063] If the determination in S35 is NO and the determination in S36 is YES, S6 is not executed, and in S7 and S8, since the wheel 10 may be loose, information urging an inspection of the fastening state of the hub bolts, etc. is notified to the vehicle manager and vehicle operator, but not to the occupant.

[0064] In this way, in this embodiment, since it is based on both the ratio of the variation value of the wheel speed difference δ and the variation value of the vehicle body lateral acceleration Gy, it is possible to more appropriately determine whether the wheel 10 is in a loose state. Furthermore, different information is notified in different ways depending on whether it is determined with high accuracy that the wheel 10 is in a loose state or whether it is determined with low accuracy that the wheel 10 is in a loose state. This makes it possible to appropriately notify information about the loose state of the wheel 10.

[0065] It is also possible to acquire the wheel state based on the variation in the vehicle body lateral acceleration, rather than based on the variation in the wheel speed difference. Example 3

[0066] In the above embodiment, the acquisition of the setting state in S2 and the looseness determination in S4 and S5 in the flowchart of Fig. 2 are executed by the vehicle ECU 20, and the notification in S8 is executed by the cloud computer 26. In contrast, in the present embodiment, the acquisition of the setting state in S2, the looseness determination in S4 and S5, the notification in S8, etc. in the flowchart of Fig. 2 are executed by the cloud computer (hereinafter, may be referred to as the server) 26. In this way, part or all of the wheel state acquisition program may be executed by the vehicle ECU 20 or the server 26.

[0067] An example of this is shown in the flowchart of Fig. 9. In the flowchart of Fig. 2 and the flowchart of Fig. 9, steps that are executed in the same manner are assigned the same step numbers and descriptions thereof will be omitted. After detecting longitudinal acceleration Gx, steering angle θ, etc. in S1, these pieces of information are supplied to server 26 in S51. Then, server 26 determines whether the vehicle state is in the set state (S2). If the determination is YES, server 26 transmits an instruction to acquire wheel speed differences to ECU 20 of the vehicle in S52. ECU 20 acquires multiple sets of wheel speed differences Δf, δr, δL, and δR by executing a wheel speed difference acquisition program represented by the flowchart of FIG. 3. Then, in S53, ECU 20 of the vehicle transmits multiple sets of data on wheel speed differences Δf, δr, δL, and δR to server 26. Server 26 receives multiple sets of data on wheel speed differences Δf, δr, δL, and δR transmitted from ECU 20 of the vehicle.

[0068] Server 26 obtains standard deviations ef, er, eL, and eR based on the wheel speed differences δf, δr, δL, and δR for each of the plurality of wheels, and obtains ratios γ and β. Then, based on the values ​​of ratios γ and β, it is determined whether or not there is a loose wheel (S4, 5). If the determination is YES, in S55, information indicating the presence of a loose wheel and the position of that wheel is transmitted to ECU 20 of the vehicle, and in S8, the vehicle manager, vehicle operator, etc. are notified via external communication means 28. The information indicating the position of the loose wheel transmitted to the vehicle is notified to the occupant, for example, by displaying it on display 22.

[0069] It is also possible that the vehicle ECU 20 determines that the vehicle is in the set state (S2), obtains a plurality of wheel speed differences δf, δr, δL, and δR, and then transmits information representing these wheel speed differences δ to the server 26. In this case, the server 26 determines whether the vehicle is loose and notifies the user. Furthermore, information such as the presence of a loose wheel can be notified directly to the vehicle occupant from the server 26. Example 4

[0070] The wheel state can be acquired using AI (artificial intelligence). For example, as shown in FIG. 10 , machine learning is performed in advance on a computer before the vehicle is shipped (or before the model is mounted on the vehicle). In this embodiment, machine learning is performed using a known machine learning algorithm such as a neural network using data on multiple wheel speed differences δf, δr, δL, and δR (corresponding to abnormal wheel speed difference data) when at least one of the four wheels 10 is in a loose state, and data on multiple wheel speed differences δf, δr, δL, and δR (corresponding to normal wheel speed difference data) when all four wheels 10 are in a normal state. This creates a trained model (trained wheel state acquisition model) 50. Then, a vehicle equipped with the trained wheel state acquisition model 50 is shipped. While the vehicle is traveling, the trained wheel state acquisition model 50 receives input of multiple wheel speed differences δf, δr, δL, δR, etc. that have actually been acquired, and outputs whether or not at least one wheel 10 is in a loose state.

[0071] A trained model can be created by inputting a large number of wheel speed differences δf, δr, δL, and δR when all four wheels 10 are in a normal state into a computer and training the computer in advance. In a vehicle equipped with this trained model, a large number of wheel speed differences δf, δr, δL, and δR are input into the trained model, and the trained model outputs whether all four wheels 10 are in a normal state.

[0072] In addition, the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0073] 10FL, 10FR, 10RL, 10RR: Wheels 12FL, 12FR, 12RL, 12RR: Wheel speed sensor 14: Steering angle sensor 16: Longitudinal acceleration sensor 18: Vehicle body lateral acceleration sensor 20: ECU 22: Display 24: Communication device 26: Server (cloud computer) 28: External communication means Patentable invention

[0074] (1) A wheel state acquisition system that acquires a wheel state, which is a state of at least one wheel among a plurality of wheels provided on a vehicle, comprising: a wheel speed detection unit that detects the wheel speed of each of the plurality of wheels; a running state detection unit that detects a running state of the vehicle; a wheel speed difference acquisition unit that acquires a wheel speed difference between two wheels among the plurality of wheels based on the wheel speeds of the plurality of wheels detected by the wheel speed detection unit when the running state of the vehicle detected by the running state detection unit is a predetermined set state; and an abnormal state acquisition unit that acquires whether at least one of the two wheels is in an abnormal state based on the wheel speed difference acquired by the wheel speed difference acquisition unit; Wheel status acquisition system including:

[0075] For example, if the maximum absolute value of the wheel speed difference between two wheels is greater than a threshold value, or if the variation value, which represents the variation in the wheel speed difference, is greater than a threshold value, it can be determined that at least one of the two wheels is in an abnormal state.

[0076] The vehicle running conditions may or may not include the wheel speeds of the wheels. The wheel speed may be the rotational speed of the wheel or the peripheral speed of the wheel.

[0077] (2) The wheel state acquisition system described in (1) above, wherein the abnormal state acquisition unit acquires whether or not the at least one wheel is in an abnormal state based on a variation value representing the variation in the wheel speed difference acquired by the wheel speed difference acquisition unit.

[0078] The variation value of the wheel speed difference may be a variance, a standard deviation, a difference between the maximum value and the minimum value, or an interquartile range.

[0079] (3) A wheel state acquisition system that acquires a wheel state, which is a state of at least one wheel among a plurality of wheels provided on a vehicle, comprising: a wheel speed detection unit that detects the wheel speed of each of the plurality of wheels; a running state detection unit that detects a running state of the vehicle; a wheel speed difference acquisition unit that acquires, when the running state of the vehicle detected by the running state detection unit is a predetermined set state, a wheel speed difference between two wheels included in one of two wheel pairs each consisting of two wheels included in the four or more wheels as the plurality of wheels, and a wheel speed difference between the two wheels included in the other of the two wheel pairs, based on the wheel speeds of each of the plurality of wheels detected by the wheel speed detection unit; an abnormality state acquisition unit that acquires whether at least one wheel among the four or more wheels is in an abnormal state based on the ratio of the wheel speed difference for each of the two wheel pairs acquired by the wheel speed difference acquisition unit; and Wheel status acquisition system including:

[0080] (4) The wheel state acquisition system described in paragraph (3) is configured such that, when the ratio of the variation values, which are values ​​representing the variation in the wheel speed difference for the two wheels of each of the two wheel pairs acquired by the wheel speed difference acquisition unit, falls outside a predetermined set range, the abnormal state acquisition unit acquires that at least one of the two wheels included in the wheel pair with the larger variation value is in an abnormal state.

[0081] The set range can be, for example, between a first set ratio and a second set ratio, or between a third set ratio and a fourth set ratio.

[0082] (5) One of the two wheel pairs includes the left and right wheels on the front side of the vehicle, the other of the two wheel pairs includes left and right wheels on the rear side of the vehicle, the wheel speed difference acquisition unit acquires a wheel speed difference between the front left and right wheels and a wheel speed difference between the rear left and right wheels based on the wheel speeds of the four or more wheels detected by the wheel speed detection unit when the running state of the vehicle detected by the running state detection unit is the set state in which the absolute value of the steering angle of the steering wheels of the vehicle is smaller than a set steering angle, The wheel state acquisition system described in (4) above, wherein the abnormal state acquisition unit acquires a ratio of the variation value of the wheel speed difference between the left and right rear wheels to the variation value of the wheel speed difference between the left and right front wheels based on the wheel speed difference between the left and right front wheels and the wheel speed difference between the left and right rear wheels acquired by the wheel speed difference acquisition unit, and acquires that at least one wheel of the left and right rear wheels is in an abnormal state if the ratio is greater than a first set ratio greater than 1, and acquires that at least one wheel of the left and right front wheels is in an abnormal state if the ratio is smaller than a second set ratio less than 1.

[0083] When the absolute value of the steering angle of the steering wheels is smaller than the set steering angle, it is estimated that the vehicle is traveling approximately straight ahead. Also, when the steering angle of the steering wheels is within a set range for the steering angle during straight ahead traveling, it can be considered that the amount of operation of the steering operation member from the neutral position is within the set range. The ratio of the wheel speed difference variation value er between the rear left and right wheels to the wheel speed difference variation value ef between the front left and right wheels is the value (er / ef) obtained by dividing the wheel speed difference variation value er between the rear left and right wheels by the wheel speed difference variation value ef between the front left and right wheels.

[0084] (6) One of the two wheel pairs includes a front wheel and a rear wheel on the left side of the vehicle, the other of the two wheel pairs includes the front and rear wheels on the right side of the vehicle, the wheel speed difference acquisition unit acquires a wheel speed difference between the left front and right front wheels based on the wheel speeds of the four or more wheels detected by the wheel speed detection unit when the running state of the vehicle detected by the running state detection unit is the set state in which the absolute value of the longitudinal acceleration of the vehicle is smaller than a set acceleration, The abnormal state acquisition unit acquires a ratio of the variation value of the wheel speed difference between the front and rear wheels on the right side to the variation value of the wheel speed difference between the front and rear wheels on the left side based on the wheel speed difference between the front and rear wheels on the left side and the wheel speed difference between the front and rear wheels on the right side acquired by the wheel speed difference acquisition unit, and when the ratio is greater than a third set ratio greater than 1, it is determined that at least one wheel of the front and rear wheels on the left side is in an abnormal state, and when the ratio is greater than 1, it is determined that at least one wheel of the front and rear wheels on the left side is in an abnormal state. Small No. 4 The wheel state acquisition system according to item (4) or (5), wherein if the ratio is smaller than a set ratio, it is determined that at least one of the front and rear wheels on the right side is in an abnormal state.

[0085] When the absolute value of the longitudinal acceleration is smaller than the set acceleration, the vehicle is considered to be traveling at a substantially constant speed. Variation value eL of wheel speed difference between the front and rear wheels on the left side of Variation value eR of wheel speed difference between the front and rear wheels on the right side against The ratio is left Variation in wheel speed difference between the front and rear wheels on the same side eL of right Variation in wheel speed difference between the front and rear wheels on the same side eR Divided by (eL / eR) is.

[0086] (7) The wheel state acquisition system includes a vehicle body lateral acceleration detection unit that detects a vehicle body lateral acceleration, which is a lateral acceleration acting on a vehicle body of the vehicle, The wheel state acquisition system according to any one of items (1) to (6), wherein the abnormal state acquisition unit further acquires a variation value representing the variation in the vehicle body lateral acceleration based on the vehicle body lateral acceleration detected by the vehicle body lateral acceleration detection unit when the vehicle's running state is acquired to be the set state, and acquires whether at least one wheel among the plurality of wheels is in an abnormal state based on the variation value.

[0087] When one of the four wheels is in an abnormal state, the change in the wheel speed of that wheel causes the lateral vibration of the vehicle body to increase, which in turn increases the change in the vehicle body lateral acceleration and the variation in the vehicle body lateral acceleration.

[0088] (8) A wheel state acquisition system as described in (7), wherein the abnormal state acquisition unit acquires that at least one wheel among the plurality of wheels is in an abnormal state when the standard deviation, which is the variation value of the vehicle body lateral acceleration, is greater than a set value.

[0089] For example, if the value (α) obtained by dividing the actual vehicle lateral acceleration variation value by the vehicle lateral acceleration variation value when all multiple wheels are normal is greater than a set value (α5), it can be determined that at least one wheel is in an abnormal state. Furthermore, if the variation value of the actual vehicle body lateral acceleration is greater than the set variation value, it can be determined that at least one wheel is in an abnormal state.

[0090] (9) A wheel state acquisition system described in any one of items (1) to (8), wherein the wheel state acquisition system defines the set state as at least one of a state in which the absolute value of the steering angle of the steering wheels of the vehicle is smaller than a set steering angle and a state in which the absolute value of the longitudinal acceleration acting on the vehicle is smaller than a set acceleration, and includes a set state acquisition unit that acquires whether the running state of the vehicle is in the set state.

[0091] The set state is a state in which the force applied to the multiple wheels is small. Whether the wheel state is abnormal or not can be accurately determined based on the wheel speed difference between the two wheels when the vehicle is running in the set state.

[0092] (10) A wheel state acquisition system described in any one of (1) to (8), including a set state acquisition unit that acquires whether the vehicle's running state is in the set state, where the set state is at least one of a state in which the absolute value of the vehicle's longitudinal acceleration changes between a state in which it is smaller than a set acceleration and a state in which it is equal to or greater than the set acceleration, and a state in which the absolute value of the steering angle of the vehicle's steering wheels changes between a state in which it is smaller than a set steering angle and a state in which it is equal to or greater than the set steering angle.

[0093] (11) A wheel state acquisition system that acquires a wheel state, which is a state of at least one wheel among four or more wheels provided on a vehicle, comprising: a wheel speed detection unit that detects the wheel speed of each of the four or more wheels; a wheel speed difference acquisition unit that acquires a wheel speed difference between two wheels in each of two wheel pairs, each consisting of two wheels included in the four or more wheels, based on the wheel speeds of each of the four or more wheels detected by the wheel speed detection unit; an abnormality state acquisition unit that acquires a ratio of the wheel speed difference for each of the two wheel pairs based on the wheel speed difference of each of the two wheel pairs acquired by the wheel speed difference acquisition unit, and acquires whether or not the at least one wheel is in an abnormal state based on the ratio; Wheel status acquisition system including:

[0094] It is not essential that the wheel speed be based on the wheel speed detected when the vehicle is in a set driving state. The wheel state acquisition system described in this section may employ any one of the technical features described in sections (1) to (10).

[0095] (12) The wheel state acquisition system according to any one of (1) to (11), wherein the abnormal state acquisition unit includes a trained model that has been machine-learned in advance using, as training data, a plurality of normal wheel speed difference data representing each of the wheel speed differences for the two wheels when the vehicle's running state is the set state when all of the plurality of wheels are in a normal state, and a plurality of abnormal wheel speed difference data representing each of the wheel speed differences when the vehicle's running state is the set state when at least one of the plurality of wheels is in an abnormal state, and the wheel speed difference acquired by the wheel speed difference acquisition unit is input into the trained model to acquire whether or not the at least one wheel is in an abnormal state.

[0096] (13) A wheel state acquisition system according to any one of (1) to (12), wherein the abnormal state acquisition unit includes a trained model that has been machine-learned in advance using a plurality of wheel speed difference data representing wheel speed differences for at least two of the plurality of wheels when the vehicle's running state is the set state when all of the plurality of wheels are in a normal state, and the wheel speed difference acquired by the wheel speed difference acquisition unit is input into the trained model to acquire whether the at least one wheel is in an abnormal state or a normal state.

[0097] (14) The abnormal state acquisition unit acquires whether or not the at least one wheel is in an abnormal state based on a variation value representing a variation in the wheel speed difference between the two wheels and a variation value representing a variation in vehicle body lateral acceleration, which is a lateral acceleration acting on the vehicle body, A wheel state acquisition system as described in any one of items (1) to (13), which includes a notification unit that notifies the abnormal state acquisition unit when the abnormal state acquisition unit acquires that at least one wheel is in an abnormal state.

[0098] The notification unit can be configured to notify in different ways depending on, for example, when the variation value of the wheel speed difference between the two wheels is large and the variation value of the vehicle body lateral acceleration is large, and when either the variation value of the wheel speed difference between the two wheels or the variation value of the vehicle body lateral acceleration is large. In the above embodiment, the display 22, the external communication means 28, etc. constitute a notification unit.

[0099] (15) A wheel state acquisition system that acquires a wheel state, which is a state of at least one wheel among a plurality of wheels provided on a vehicle, comprising: a vehicle body lateral acceleration detection unit that detects a vehicle body lateral acceleration, which is an acceleration acting in a lateral direction on a vehicle body of the vehicle; a running state detection unit that detects a running state of the vehicle; an abnormal state acquisition unit that acquires, when the running state detection unit acquires that the running state of the vehicle is a straight running state, whether or not the at least one wheel is in an abnormal state based on the variation in the vehicle body lateral acceleration detected by the vehicle body lateral acceleration detection unit; Wheel status acquisition system including:

[0100] The wheel state acquisition system according to this aspect can employ any of the technical features described in (1) to (14). For example, it is possible to determine whether or not at least one wheel is in an abnormal state based on a variation value that indicates variation in the vehicle body lateral acceleration.

[0101] (16) A wheel state acquisition method for acquiring a wheel state, which is a state of at least one of a plurality of wheels provided on a vehicle, comprising: a setting state acquisition step of acquiring whether or not the running state of the vehicle is in a predetermined setting state; a wheel speed difference acquisition step of acquiring a wheel speed difference between two wheels included in one of two wheel pairs each consisting of two wheels included in four or more wheels as the plurality of wheels, and a wheel speed difference between two wheels included in the other of the two wheel pairs, based on the wheel speeds of the plurality of wheels detected by the wheel speed detection unit in the set state acquisition step; an abnormality state acquisition step of acquiring whether or not at least one wheel among the plurality of wheels is in an abnormal state based on a ratio of variation values ​​representing variations in the wheel speed differences for each of the two wheel pairs acquired in the wheel speed difference acquisition step; A wheel status acquisition method including:

[0102] The wheel state acquisition method described in this section can employ any of the technical features described in sections (1) to (15).

Claims

1. A wheel state acquisition system that acquires a wheel state, which is a state of at least one wheel among a plurality of wheels provided on a vehicle, comprising: a wheel speed detection unit that detects the wheel speed of each of the plurality of wheels; a running state detection unit that detects a running state of the vehicle; a wheel speed difference acquisition unit that acquires, when the running state of the vehicle detected by the running state detection unit is at least one of a state in which an absolute value of a steering angle of a steering wheel among the plurality of wheels of the vehicle is smaller than a set steering angle and a state in which an absolute value of a longitudinal acceleration acting on the vehicle is smaller than a set acceleration, a wheel speed difference acquisition unit that acquires, based on the wheel speeds of each of the plurality of wheels detected by the wheel speed detection unit, a wheel speed difference between two wheels included in one of two wheel pairs each consisting of two wheels included in the plurality of wheels, four or more wheels. and an abnormal state acquisition unit that, when a ratio of variation values, which is a value representing the variation in wheel speed differences for the two wheels of each of the two wheel pairs acquired by the wheel speed difference acquisition unit, falls outside a predetermined set range, acquires that at least one of the two wheels included in the wheel pair with the larger variation value is in an abnormal state in which the wheel is loosely fastened to a vehicle body member.

2. one of the two wheel pairs includes a front left and right wheel of the vehicle, the other of the two wheel pairs includes left and right wheels on the rear side of the vehicle, the wheel speed difference acquisition unit acquires a wheel speed difference between the front left and right wheels and a wheel speed difference between the rear left and right wheels based on the wheel speeds of the four or more wheels detected by the wheel speed detection unit when the running state of the vehicle is the set state in which the absolute value of the steering angle of the steering wheels of the vehicle is smaller than a set steering angle, 2. The wheel state acquisition system according to claim 1, wherein the abnormal state acquisition unit acquires a ratio of the variation value of the wheel speed difference between the left and right rear wheels to the variation value of the wheel speed difference between the left and right front wheels based on the wheel speed difference between the left and right front wheels and the wheel speed difference between the left and right rear wheels acquired by the wheel speed difference acquisition unit, and acquires that at least one wheel of the left and right rear wheels is in the abnormal state if the ratio is greater than a first set ratio greater than 1, and acquires that at least one wheel of the left and right front wheels is in the abnormal state if the ratio is smaller than a second set ratio less than 1.

3. one of the two wheel pairs includes a front wheel and a rear wheel on the left side of the vehicle; the other of the two wheel pairs includes a front and rear wheel on the right side of the vehicle, the wheel speed difference acquisition unit acquires a wheel speed difference between the left front and right front wheels based on the wheel speeds of the four or more wheels detected by the wheel speed detection unit when the running state of the vehicle is the set state in which the absolute value of the longitudinal acceleration of the vehicle is smaller than a set acceleration, 2. The wheel state acquisition system according to claim 1, wherein the abnormal state acquisition unit acquires a ratio of the variation value of the wheel speed difference between the left front and rear wheels to the variation value of the wheel speed difference between the right front and rear wheels based on the wheel speed difference between the left front and rear wheels and the wheel speed difference between the right front and rear wheels acquired by the wheel speed difference acquisition unit, and determines that at least one of the left front and rear wheels is in the abnormal state if the ratio is greater than a third set ratio greater than 1, and determines that at least one of the right front and rear wheels is in the abnormal state if the ratio is smaller than a fourth set ratio less than 1.

4. The wheel state acquisition system detects a lateral acceleration acting on the body of the vehicle. a vehicle body lateral acceleration detection unit that detects acceleration, 4. The wheel state acquisition system according to claim 1, wherein the abnormal state acquisition unit further acquires whether or not the at least one wheel is in the abnormal state based on the variation in the vehicle body lateral acceleration detected by the vehicle body lateral acceleration detection unit when the vehicle's running state detected by the running state detection unit is the set state in which the absolute value of the steering angle of the steered wheels is smaller than the set steering angle.

5. 4. The wheel state acquisition system according to claim 1, wherein the abnormal state acquisition unit includes a trained model that has been previously machine-learned using, as training data, a plurality of normal wheel speed difference data representing each of the wheel speed differences between the two wheels when the vehicle's running state is the set state when all of the plurality of wheels are in a normal state, and a plurality of abnormal wheel speed difference data representing each of the wheel speed differences when the vehicle's running state is the set state when at least one of the plurality of wheels is in the abnormal state, and the wheel speed difference acquired by the wheel speed difference acquisition unit is input into the trained model to acquire whether or not the at least one wheel is in the abnormal state.

6. A wheel state acquisition method for acquiring a wheel state, which is a state of at least one of a plurality of wheels provided on a vehicle, comprising: a set state acquisition step of acquiring whether the running state of the vehicle is in at least one of a state in which the absolute value of the steering angle of the steering wheels of the vehicle is smaller than a set steering angle and a state in which the absolute value of the longitudinal acceleration acting on the vehicle is smaller than a set acceleration; a wheel speed difference acquisition step of acquiring a wheel speed difference between two wheels included in one of two wheel pairs each consisting of two wheels included in four or more wheels as the plurality of wheels, and a wheel speed difference between two wheels included in the other of the two wheel pairs, based on the wheel speeds of the plurality of wheels detected by the wheel speed detection unit in the set state acquisition step; and an abnormal state acquisition step of acquiring, when a ratio of variation values ​​representing variation in the wheel speed differences for each of the two wheel pairs acquired in the wheel speed difference acquisition step falls outside a predetermined set range, determining that at least one of the two wheels included in the wheel pair having the larger variation value is in an abnormal state in which the wheel is loosely fastened to a vehicle body member.

Images