WO2019088023A1 - Road surface state estimation device - Google Patents

Abstract

A first control unit (11) of a tire-side device (1) determines that a road surface state has changed. A second control unit (26) of a vehicle body-side system (2) estimates that there has been a change in the road surface state on the basis of information of a peripheral device (24), and transmits vehicle body-side information to the tire-side device (1) when there is a change in the road surface state. In the tire-side device (1), road surface data including a current feature quantity is transmitted from the tire-side device (1) at a timing when the road surface state has changed.

Description

Road surface condition estimation device Cross-reference to related applications

This application is based on Japanese Patent Application No. 2017-209401 filed on October 30, 2017 and Japanese Patent Application No. 2018-108583 filed on June 6, 2018, which are incorporated herein by reference. The contents of the description are incorporated by reference.

The present disclosure detects a vibration received by a tire and generates a road surface data indicating a road surface state based on the vibration data, and a vehicle body side system that receives the road surface data and estimates the road surface state. The present invention relates to a state estimation device.

Conventionally, in Patent Document 1, there is provided a road surface state estimation method including an acceleration sensor on the back of the tire tread, detecting the vibration applied to the tire by the acceleration sensor, and estimating the road surface state based on the detection result of the vibration. Proposed. In this road surface state estimation method, the feature vector is extracted from the tire's vibration waveform detected by the acceleration sensor, and the similarity between the extracted feature vector and all the support vectors stored for each type of road surface is calculated. , To estimate the road surface condition. For example, the kernel function is used to calculate the degree of similarity between the extracted feature vector and all the support vectors, and the kind of road surface having the highest degree of similarity, eg, dry road surface, wet road surface, etc. Presumed. By such a road surface state estimation method, it is possible to perform road surface determination with high robustness.

JP, 2016-107833, A

The road surface state estimation method shown in Patent Document 1 mentioned above is not sure whether the calculation of the degree of similarity is carried out by the control unit provided in the tire or in the vehicle side system, but the calculation load of the degree of similarity is The high cost causes the following problems.

For example, when the control unit provided in the tire calculates the degree of similarity and estimates the road surface condition, and transmits the estimation result to the vehicle body system, the support unit is stored in the control unit provided in the tire. It is necessary to perform data processing of similarity calculation. For this reason, the amount of power consumption is enormous in the tire, and the amount of memory consumption in the control unit is also enormous because enormous data storage and data processing are required.

In addition, the control unit provided in the tire only extracts the feature vector, transmits the data to the vehicle body side system, and calculates the similarity to all the support vectors in the vehicle body side system to determine the road surface state. It can also be done. In that case, since the timing of data transmission can not be determined, the frequency of communication can not but be increased, and power consumption is increased by high frequency data transmission.

The present disclosure has a first object to provide a road surface state estimation device capable of realizing power saving of at least a tire side device. Another object of the present invention is to provide a road surface state estimation device including a tire side device capable of realizing memory saving and power saving of a control unit in a tire.

The road surface state estimation device according to one aspect of the present disclosure includes a tire side device disposed in a tire and a vehicle body side system disposed in the vehicle body side. The tire side device performs data communication between a vibration detection unit that outputs a detection signal according to the magnitude of the vibration of the tire, a first control unit that creates road surface data based on the detection signal, and a vehicle body side system. And a first transmission / reception unit to perform. In addition, the vehicle body side system is based on the information on the road surface condition acquired by the peripheral device that acquires information on the road surface condition, the second transmitting / receiving unit that performs data communication with the tire device, and the road surface condition When it is determined that there has been a change, the second transmitting / receiving unit causes the tire transmitting / receiving unit to transmit vehicle body side information indicating that there is a change in the road surface condition, and the road surface based on the road surface data received by the second transmitting / receiving unit. And a second control unit configured to estimate a state. Then, when it is determined that the first control unit in the tire-side device determines that the road surface state has changed based on the detection signal, and the change determination unit determines that the road surface state has changed, And a transmission control unit that causes the first transmission / reception unit to transmit road surface data when the vehicle body side information is received.

When the road surface state is estimated by such a road surface state estimation device, transmission of the road surface data from the tire side device is made to be only at the change timing of the road surface state. Specifically, the road surface data is transmitted from the tire side device only at the timing when it is determined that the road surface state has been changed by the tire side device or the vehicle body side system. Therefore, the communication frequency can be reduced, and power saving of the first control unit in the tire can be realized.

Further, not only the structure provided with the support vector storage unit for storing the support vector in the first control unit of the tire-side device but also the structure not provided with the support vector can be realized. When the support vector storage unit is not provided, the memory saving of the first control unit in the tire can be achieved.
In addition, the parenthesized reference symbol attached to each component etc. shows an example of the correspondence of the component etc. and the specific component etc. as described in the embodiment to be described later.

It is the figure which showed the block configuration in the vehicle mounting state of the tire apparatus concerning 1st Embodiment. It is a block diagram showing details of a tire side device and a vehicle body side system. It is a cross-sectional schematic diagram of the tire in which the tire side apparatus was attached. It is an output voltage waveform figure of the acceleration acquisition part at the time of tire rotation. It is a figure which shows a mode that the detection signal of the acceleration acquisition part was divided for every time window of predetermined time width | variety T. FIG. The determinants Xi (r) and Xi (r-1) in each section obtained by dividing the time axis waveform at the time of the current rotation of the tire and the time axis waveform at the time before one rotation by the time window of the predetermined time width T _Is a diagram showing the relationship between the distance _yz and the distance _yz . It is a flowchart of the vehicle body side determination processing which the control part of a vehicle body side system performs. It is a flowchart of the tire side determination process which the control part of a tire side apparatus performs. It is a flowchart of the data transmission process which the control part of a tire side apparatus performs. It is a flowchart of the road surface state estimation process which the control part of the vehicle body side system performs. It is the block diagram which showed the detail of the tire side device and vehicle body side system with which the tire device concerning a 2nd embodiment is equipped. It is a block diagram showing details of a tire side device and a vehicle body side system provided in a tire device according to a third embodiment. It is a flowchart of the tire side determination processing demonstrated in 3rd Embodiment.

Hereinafter, embodiments of the present disclosure will be described based on the drawings. In the following embodiments, parts that are the same as or equivalent to each other will be described with the same reference numerals.

First Embodiment
A tire device 100 having a road surface state estimation function according to the present embodiment will be described with reference to FIGS. 1 to 10. The tire device 100 according to the present embodiment estimates the road surface state during traveling based on the vibration applied to the ground contact surface of the tire provided on each wheel of the vehicle, and notifies of the danger of the vehicle or the vehicle based on the road surface state. It performs exercise control and the like.

As shown in FIG. 1 and FIG. 2, the tire device 100 is configured to have a tire side device 1 provided on the wheel side and a vehicle body side system 2 including each part provided on the vehicle body side. The vehicle body side system 2 includes a receiver 21, an electronic control unit for brake control (hereinafter referred to as a brake ECU) 22, an informing device 23, a peripheral device 24, and the like. The part of the tire device 100 that realizes the road surface state estimation function corresponds to the road surface state estimation device. In the case of this embodiment, the receiver 21 and the peripheral device 24 in the tire side device 1 and the vehicle body side system 2 constitute a road surface state estimation device.

The tire device 100 of the present embodiment transmits data (hereinafter referred to as road surface data) according to the road surface condition on the traveling road surface of the tire 3 from the tire device 1 and receives the road surface data by the receiver 21 Make an estimate of Specifically, the tire side device 1 transmits road surface data when it is determined that the road surface state has changed. Further, the vehicle body side system 2 also determines that there is a change in the road surface state based on the information from the peripheral device 24, and when there is a change in the road surface state, information to that effect (hereinafter referred to as the vehicle body side The information is transmitted to the tire side device 1). That is, the tire-side device 1 transmits road surface data also when the vehicle-side information is transmitted, in addition to the case where it is determined that the road surface state has changed by itself. Then, the receiver 21 receives road surface data sent when there is a change in the road surface condition, and estimates the road surface condition based on the received road surface data.

In addition, the tire device 100 transmits the estimation result of the road surface condition in the receiver 21 to the notification device 23, and causes the notification device 23 to notify the estimation result of the road surface condition. This makes it possible to convey the road surface condition to the driver, for example, a dry road, a wet road, or a frozen road, and to warn the driver if the road surface is slippery. In addition, the tire device 100 transmits a road surface state to the brake ECU 22 or the like that performs vehicle motion control so that vehicle motion control for avoiding a danger is performed. For example, at the time of freezing, the braking force generated with respect to the brake operation amount is weakened as compared to the case of the dry road, so that the vehicle motion control corresponding to the time when the road surface μ is low is achieved. Specifically, the tire side device 1 and the vehicle body side system 2 are configured as follows.

The tire side device 1 is disposed in each of the tires 3 so that bidirectional communication with the vehicle side system 2 is enabled. Specifically, as shown in FIG. 2, the tire side device 1 is configured to include the acceleration acquiring unit 10, the control unit 11 and the data communication unit 12, and as shown in FIG. 3, the tread of the tire 3 31 is provided on the back side.

The acceleration acquisition unit 10 constitutes a vibration detection unit for detecting a vibration applied to the tire 3. For example, the acceleration acquisition unit 10 is configured of an acceleration sensor. When the acceleration acquiring unit 10 is an acceleration sensor, for example, the acceleration acquiring unit 10 is a direction in contact with the circular track drawn by the tire-side device 1 when the tire 3 rotates, that is, indicated by an arrow X in FIG. A detection signal of acceleration is output as a detection signal corresponding to the vibration in the tire tangential direction. More specifically, the acceleration acquiring unit 10 generates, as a detection signal, an output voltage in which one of the two directions indicated by the arrow X is positive and the opposite direction is negative. For example, the acceleration acquisition unit 10 performs acceleration detection at a predetermined sampling cycle which is set to a cycle shorter than one rotation of the tire 3 and outputs it as a detection signal.

The control unit 11 corresponds to a first control unit, is constituted by a known microcomputer including a CPU, a ROM, a RAM, an I / O and the like, and performs the above-described processing according to a program stored in the ROM and the like. . The control unit 11 is configured to include a feature quantity extraction unit 11a, a feature quantity storage unit 11b, a change determination unit 11c, and a transmission control unit 11d as functional units that perform those processes.

The feature amount extraction unit 11a extracts the feature amount of the tire vibration by processing the detection signal using the detection signal output from the acceleration acquisition unit 10 as a detection signal representing the vibration data in the tire tangential direction. In the case of the present embodiment, the feature amount of the tire G is extracted by performing signal processing on a detection signal of the acceleration of the tire 3 (hereinafter referred to as a tire G). Also, the feature amount extraction unit 11a transmits data including the extracted feature amount to the data communication unit 12 as road surface data via the transmission control unit 11d. The details of the feature quantities referred to here will be described later.

The feature amount storage unit 11 b stores the feature amount extracted by the feature amount extraction unit 11 a one turn before the tire 3 (hereinafter referred to as the “previous feature amount”). Since the fact that the tire 3 has made one rotation can be confirmed by a method described later, every time the tire 3 makes one rotation, the feature amount for one rotation is stored. The feature amount for one rotation of the tire 3 may be updated every time the tire 3 makes one rotation, or a plurality of rotations may be stocked, and the tire 3 makes one rotation every time the tire 3 makes one rotation. You may delete old data. However, from the viewpoint of saving memory of the control unit 11 in the tire 3, it is preferable to reduce the amount of data to be stored, and therefore, it is preferable to update data each time the tire 3 makes one rotation.

The change determination unit 11c is configured to extract the feature quantity extracted by the feature quantity extraction unit 11a during the current rotation of the tire 3 (hereinafter referred to as the present feature quantity) and the previous feature quantity of the tire 3 stored in the feature quantity storage unit 11b. It is determined whether or not there is a change in road surface condition based on. Further, as described later, the change determination unit 11c also determines the presence or absence of the change in the road surface state based on whether or not the vehicle body side information is received from the receiver 21 of the vehicle body side system 2. When the change determination unit 11c determines that there is a change in the road surface state, it transmits a control signal indicating that to the transmission control unit 11d.

The change determination unit 11 c distinguishes the determination of the presence or absence of the change in the road surface state based on the feature amount in the tire device 1 and the determination of the presence or absence of the change in the road surface state based on the vehicle body side information from the vehicle body side system 2. The decision is being made. In the following description, the former determination is referred to as "tire side determination" and the latter determination is referred to as "vehicle side determination".

The transmission control unit 11 d controls data transmission from the data communication unit 12. When the transmission control unit 11d receives a control signal indicating that there is a change in the road surface condition from the change determination unit 11c, it transmits the road surface data including the current feature amount extracted by the feature amount extraction unit 11a at that time. Tell the communication unit 12. For this reason, in the case of the present embodiment, the road surface data indicates data communication if the result of the determination on the road surface state is a change either in the tire side determination result or the vehicle body side determination result. It is transmitted to the part 12.

The data communication unit 12 constitutes a first transmission / reception unit, and performs data communication with a data communication unit 25 described later of the receiver 21 in the vehicle body side system 2. Although the data communication unit 12 is described here as one configuration, the data communication unit 12 may be configured separately for the transmission unit and the reception unit. Various forms of bi-directional communication can be applied, such as Bluetooth communication including BLE (abbreviation of Bluetooth Low Energy) communication, wireless LAN such as wifi (abbreviation of Local Area Network), Sub-GHz communication, Ultra-wide band communication, ZigBee, etc. can be applied. "Bluetooth" is a registered trademark.

For example, when the road surface data is transmitted from the transmission control unit 11 d, the data communication unit 12 transmits the road surface data including the feature amount at this time. The timing of data transmission from the data communication unit 12 is controlled by the transmission control unit 11 d, so data transmission is not performed every time the tire 3 makes one rotation, and when there is a change in the road surface condition Data transmission is performed only in

Further, when the vehicle-body-side information is transmitted from the data communication unit 25, the data communication unit 12 receives it and transmits it to the change determination unit 11c. Thus, the change determination unit 11c can determine the presence or absence of the change in the road surface state based on the transmitted vehicle body side information.

On the other hand, as shown in FIG. 2, the receiver 21 is configured to have a data communication unit 25 and a control unit 26.

The data communication unit 25 is a part that configures a second transmission / reception unit that performs data communication with the tire side device 1, and road surface data including the present feature amount transmitted from the data communication unit 12 of the tire side device 1 It plays a role of receiving and communicating to the control unit 26. Also, when the vehicle-body-side information indicating that there is a change in the road surface state is transmitted from the control unit 26 based on the information of the peripheral device 24, it also plays a role of transmitting it to the data communication unit 12 of each tire-side device 1. Although the data communication unit 25 is described here as one configuration, the data communication unit 25 may be configured separately for the transmission unit and the reception unit.

The control unit 26 corresponds to a second control unit, is configured by a well-known microcomputer including a CPU, a ROM, a RAM, an I / O, and the like, and performs various processes in accordance with a program stored in the ROM or the like. The control unit 26 includes a support vector storage unit 26a, a state estimation unit 26b, and a change determination unit 26c as functional units that perform various processes.

The support vector storage unit 26a stores and stores support vectors for each type of road surface. The support vector is a feature that serves as an example, and is obtained, for example, by learning using a support vector machine. The vehicle equipped with the tire-side device 1 is run experimentally for each type of road surface, and at that time the feature quantity extracted by the feature quantity extraction unit 11a is learned for a predetermined number of tire rotations, and a typical feature quantity among them What is extracted a predetermined number of times is taken as a support vector. For example, feature amounts for one million rotations are learned for each type of road surface, and typical feature amounts for 100 rotations are extracted therefrom as support vectors.

The state estimation unit 26 b compares the current feature amount sent from the tire-side device 1 received by the data communication unit 25 with the support vector for each type of road surface stored in the support vector storage unit 26 a, Estimate the road surface condition. For example, the feature amount is compared with the support vector for each type of road surface, and the road surface of the support vector having the closest feature amount this time is estimated to be the current traveling road surface.

The change determination unit 26c determines that there is a change in the road surface condition based on the information from the peripheral device 24, and when there is a change in the road surface condition, the data communication unit 25 indicates the vehicle side information to that effect. To the data communication unit 12 of each tire-side device 1. In addition, since various things can be used for the peripheral device 24 as will be described later, the processing performed by the change determination unit 26 c differs depending on which device is applied as the peripheral device 24. Will be described later.

In addition, when the road surface state is estimated by the state estimation unit 26b, the control unit 26 transmits the estimated road surface state to the notification device 23, and notifies the driver of the road surface condition from the notification device 23 as necessary. As a result, the driver can keep in mind the driving corresponding to the road surface condition, and the danger of the vehicle can be avoided. For example, the road surface state estimated through the notification device 23 may be displayed at all times, or the road surface state is determined only when the driving needs to be performed more carefully, such as a wet road or a frozen road. The status may be displayed to warn the driver. Further, the road surface state is transmitted from the receiver 21 to the ECU for executing the vehicle movement control such as the brake ECU 22, and the vehicle movement control is performed based on the transmitted road surface state.

The brake ECU 22 constitutes a braking control device that performs various brake control. Specifically, the brake ECU 22 controls the braking force by increasing or decreasing the wheel cylinder pressure by driving an actuator for controlling the brake fluid pressure. The brake ECU 22 can also control the braking force of each wheel independently. When the road surface condition is transmitted from the receiver 21 by the brake ECU 22, the braking force is controlled as the vehicle motion control based thereon. For example, the brake ECU 22 weakens the braking force generated with respect to the amount of brake operation by the driver, as compared to a dry road surface, when it is indicated that the road surface state transmitted is a frozen road. Thereby, it is possible to suppress the wheel slip and to avoid the danger of the vehicle.

Further, the notification device 23 is configured of, for example, a meter indicator, and is used when notifying the driver of the road surface condition. When the notification device 23 is configured by a meter indicator, the driver is disposed at a visible position during driving of the vehicle, for example, installed in an instrument panel of the vehicle. The meter display can notify the driver of the road surface condition visually by performing display in a mode in which the road surface condition can be grasped when the road surface condition is transmitted from the receiver 21.

The notification device 23 can also be configured by a buzzer, a voice guidance device, or the like. In that case, the notification device 23 can aurally notify the driver of the road surface condition by buzzer sound or voice guidance. Moreover, although the meter display was mentioned as the example as the alerting | reporting apparatus 23 which alert | reports visual, you may comprise the alerting | reporting apparatus 23 by the indicator which displays information, such as a head-up display.

The peripheral device 24 is configured by various devices provided in the vehicle, and plays a role of acquiring information on the road surface state and transmitting it to the change determination unit 26c. The various devices provided in the vehicle may be any device as long as it can acquire information on the road surface state. For example, an on-vehicle camera, a wiper device, a brake ECU 22 or the like may be applied.

When an on-vehicle camera is applied as the peripheral device 24, image data of a road surface in front of the vehicle is acquired by the on-vehicle camera, and the image data is transmitted to the change determination unit 26c. In this case, the change determination unit 26c analyzes the image data of the on-vehicle camera, and determines that there is a change in the road surface state based on the analysis result. When a wiper device is applied as the peripheral device 24, drive information of the wiper device is transmitted to the change determination unit 26c. When the wiper device is driven, it is when it is raining or snowing. Therefore, the change determination unit 26c acquires, from the control unit of the wiper apparatus, information indicating that the wiper drive has been performed, and determines that there is a change in the road surface state based on the information. In addition, when the brake ECU 22 is applied as the peripheral device 24, information related to the road surface state used for various controls performed by the brake ECU 22 is transmitted to the change determination unit 26c. The brake ECU 22 performs various controls such as ABS (abbreviation of Antilock Brake System) and VSC (abbreviation of Vehicle stability control), and estimates a road surface friction coefficient and a road surface state. Therefore, when the brake ECU 22 transmits information on the road surface condition, the change determination unit 26c determines that the road surface condition has changed based on the information. A known method may be applied to the estimation of the road surface state based on the analysis of the image data acquired by the on-vehicle camera and the estimation of the road surface state by the brake ECU 22.

The tire device 100 according to the present embodiment is configured as described above. In addition, each part which comprises the vehicle body side system 2 is connected through in-vehicle LAN (abbreviation of Local Area Network) by CAN (abbreviation of Controller Area Network) communication etc., for example. Therefore, each part can communicate information with each other through the in-vehicle LAN.
Next, the details of the determination of the change of the road surface state by the feature amount extracted by the above-described feature amount extraction unit 11a and the change determination unit 11c will be described.

First, the feature quantities extracted by the feature quantity extraction unit 11a will be described. The feature amount referred to here is an amount indicating the feature of the vibration applied to the tire 3 acquired by the acceleration acquiring unit 10, and is expressed as, for example, a feature vector.

An output voltage waveform of a detection signal of the acceleration acquisition unit 10 at the time of tire rotation is, for example, a waveform shown in FIG. 4. As shown in this figure, the output voltage of the acceleration acquiring unit 10 has a maximum value at the start of the ground contact when the portion of the tread 31 corresponding to the location where the acceleration acquiring unit 10 starts to contact with the rotation of the tire 3. Take. Hereinafter, the peak value at the start of grounding where the output voltage of the acceleration acquiring unit 10 has a maximum value is referred to as a first peak value. Furthermore, as shown in FIG. 4, when the tire 3 is rotated, the acceleration acquisition unit 10 is not in contact with the ground when the portion corresponding to the location where the acceleration acquisition unit 10 is disposed is in contact with the ground. Output voltage has a local minimum value. Hereinafter, the peak value at the end of grounding where the output voltage of the acceleration acquiring unit 10 has a local minimum value is referred to as a second peak value.

The peak value of the output voltage of the acceleration acquisition unit 10 at such timing is as follows. That is, when a portion of the tread 31 corresponding to the location where the acceleration acquiring unit 10 is placed on the ground as the tire 3 rotates, the portion of the tire 3 having a substantially cylindrical surface in the vicinity of the acceleration acquiring unit 10 is It is pressed and deformed into a planar shape. By receiving the impact at this time, the output voltage of the acceleration acquiring unit 10 takes a first peak value. In addition, when a portion of the tread 31 corresponding to the location where the acceleration acquisition unit 10 is disposed is separated from the ground contact surface as the tire 3 rotates, the tire 3 is released from pressure in the vicinity of the acceleration acquisition unit 10 It returns to approximately cylindrical shape from. By receiving an impact when the shape of the tire 3 returns to the original shape, the output voltage of the acceleration acquiring unit 10 takes a second peak value. In this manner, the output voltage of the acceleration acquiring unit 10 takes the first and second peak values at the start of grounding and at the end of grounding, respectively. Further, since the direction of the impact when the tire 3 is pressed and the direction of the impact when released from the pressing are opposite, the sign of the output voltage is also the opposite.

Here, an instant at which a portion of the tire tread 31 corresponding to the location where the acceleration acquisition unit 10 is disposed contacts the road surface is referred to as a "step-in area", and an instant at which it is separated from the road surface is referred to as a "kick-out area". The “step-in area” includes the timing at which the first peak value is obtained, and the “kick-out area” includes the timing at which the second peak value is obtained. In addition, the area in front of the stepping area is the area before the stepping area, and the area from the stepping area to the kicking area, that is, the portion of the tire tread 31 corresponding to the location where the acceleration acquiring unit 10 is placed "Region after kicking out" is taken as "area after kicking out". As described above, it is possible to divide the period in which the portion of the tire tread 31 corresponding to the arrangement location of the acceleration acquiring unit 10 is in contact with the ground and the region before and after the period. In FIG. 4, five areas R1 to R5 are “pre-step-in area”, “step-in area”, “kick-out front area”, “kick-out area”, and “post-kick out area” in the detection signal in this order. It is shown as.

The vibration generated in the tire 3 fluctuates in each of the divided areas according to the road surface state, and the detection signal of the acceleration acquiring unit 10 changes, so that the frequency analysis of the detection signal of the acceleration acquiring unit 10 in each area is performed. , Detects the road surface condition on the traveling road surface of the vehicle. For example, in a slippery road surface condition such as a snowy road, the shear force at the time of kicking is reduced, so the band value selected from the 1 kHz to 4 kHz band becomes smaller in the kicking out region R4 and the after kicking out region R5. As described above, since each frequency component of the detection signal of the acceleration acquisition unit 10 changes according to the road surface state, it is possible to determine the road surface state based on the frequency analysis of the detection signal.

Therefore, as shown in FIG. 5, the feature quantity extraction unit 11a detects the detection signal of the acceleration acquisition unit 10 for one rotation of the tire 3 that has a continuous time axis waveform for each time window of a predetermined time width T. The feature quantity is extracted by dividing into a plurality of sections and performing frequency analysis in each section. Specifically, the power spectrum value in each frequency band, that is, the vibration level in the specific frequency band is determined by performing frequency analysis in each section, and this power spectrum value is used as the feature amount.

In addition, the number of the division divided by the time window of time width T is a value which changes according to the rotational speed of the tire 3 in more detail according to the vehicle speed. In the following description, the number of sections for one tire rotation is n (where n is a natural number).

For example, the power obtained by passing the detection signal of each section through five band pass filters of a plurality of specific frequency bands, for example, 0 to 1 kHz, 1 to 2 kHz, 2 to 3 kHz, 3 to 4 kHz, or 4 to 5 kHz Spectral values are used as feature quantities. This feature quantity is called a feature vector, and a feature vector Xi of a section i (where i is a natural number of 1 ≦ i ≦ n) is represented by _{aik when} the power spectrum value of each specific frequency band is indicated by _aik It is expressed as in the following equation as a matrix having.

Note that k in the power spectrum value a _ik is the number of specific frequency bands, that is, the number of band pass filters, and k = 1 to 5 when the 0 to 5 kHz band is divided into five as described above. Then, the determinant X collectively indicating the feature vectors X1 to Xn of all the sections 1 to n is expressed by the following equation.

This determinant X is an expression representing the feature amount for one rotation of the tire. The feature amount extraction unit 11 a extracts the feature amount represented by the determinant X by performing frequency analysis on the detection signal of the acceleration acquisition unit 10.

Subsequently, determination of the change of the road surface state by the change determination unit 11c will be described. This determination is performed by calculating the similarity using the current feature amount extracted by the feature amount extraction unit 11a and the previous feature amount stored in the feature amount storage unit 11b.

As described above, with regard to the determinant X representing the feature, the determinant of the current feature is X (r), and the determinant of the previous feature is X (r−1), and the power serving as each element of each determinant Let the spectral value a _{ik be represented} by a (r) _ik , a (r−1) _ik . In that case, the determinant X (r) of the current feature and the determinant X (r−1) of the previous feature are expressed as follows.

The degree of similarity indicates the degree of similarity between the feature quantities indicated by the two determinants, meaning that the higher the degree of similarity, the more similar. In the case of the present embodiment, the change determination unit 11 c determines the degree of similarity using the kernel method, and determines the change in road surface state based on the degree of similarity. Here, the inner product of the determinant X (r) at the time of the current rotation of the tire 3 and the determinant one rotation before is X (r-1), in other words, for each time window of a predetermined time width T in the feature space The distance between the coordinates indicated by the feature vector Xi of the sections divided by is calculated and used as the similarity.

For example, as shown in FIG. 6, regarding the time axis waveform of the detection signal of the acceleration acquiring unit 10, the time axis waveform at the time of the current rotation of the tire 3 and the time axis waveform at one rotation before are each set to a predetermined time width T Divide into each section with the time window of. In the case of the illustrated example, since each time axis waveform is divided into five sections, n = 5 and i is represented by 1 ≦ i ≦ 5. Here, as shown in the figure, the feature vector Xi of each section during the current rotation is Xi (r), and the feature vector of each section before one rotation is Xi (r-1). In that case, with respect to the distance K _yz between the coordinates indicated by the feature vector Xi of each section, the features of each section before one rotation and the lateral ridge including the feature vector Xi (r) of each section at the current rotation It is indicated as a weir that intersects with a vertical weir containing the vector Xi (r-1). Note that y is the one obtained by rewriting i in Xi (r-1), and z is the one obtained by rewriting i in Xi (r) for the distance _Kyz . Further, the vehicle speed does not change significantly between the current rotation and one rotation before, so basically the number of sections at each rotation is equal.

In the case of this embodiment, since the feature vector Xi is obtained by dividing into five specific frequency bands, the feature vector Xi of each section is represented in a six-dimensional space aligned with the time axis, and the features of the sections The distance between the coordinates indicated by the vector Xi is the distance between the coordinates in the six-dimensional space. However, the distance between coordinates indicated by the feature vector Xi of each section is smaller as the feature quantities are similar and larger as they are not similar, so the smaller the distance is, the higher the similarity is, and the larger the distance is It indicates that the degree of similarity is low.

For example, when divisions 1 to n are made by time division, the distance K _yz between the coordinates indicated by the feature vectors of the divisions 1 is expressed by the following equation.

In this manner, the distance _{K yz} between coordinates indicated by the feature vector of the compartment between time-division determined for all sections, and calculates the distance _{K yz} sum _{K total} of all sections fraction, the total sum _{K total} similarity It is used as the corresponding value. Then, the total sum K _total is compared with a predetermined threshold Th, and if the _total sum K _total is larger than the threshold Th, the similarity is low and it is determined that there is a change in road surface condition, and the total sum K _total is smaller than the threshold Th For example, it is determined that the degree of similarity is high and there is no change in the road surface state.

Here, although the sum K _total of the distance K _yz between two coordinates indicated by the feature vector of each section is used as a value corresponding to the degree of similarity, another parameter may be used as a parameter indicating the degree of similarity. . For example, as a parameter indicating the degree of similarity, an average distance K _ave which is an average value of the distances K _yz obtained by dividing the _total sum K _total by the number of sections can be used. Also, as shown in Patent Document 1, various kernel functions can be used to determine the degree of similarity. Further, instead of using all of the feature vectors, it is also possible to calculate the similarity by excluding paths with low similarity from them.

Subsequently, the operation of the tire device 100 according to the present embodiment will be described with reference to FIGS. 7 to 10.

First, in the vehicle body side system 2, the change determination unit 26c performs the vehicle body side determination process shown in FIG. 7 based on the information on the road surface state acquired from the peripheral device 24. This process is performed, for example, during a predetermined control cycle while the ignition (not shown) is on, preferably while the vehicle is traveling.

As shown in FIG. 7, the change determination unit 26 c executes a process of acquiring information on the road surface state from the peripheral device 24 in step S <b> 100. For example, when an on-vehicle camera is applied as the peripheral device 24, acquisition of image data, information indicating that the wiper device is driven when the wiper device is applied, road surface when the brake ECU 22 is applied Information on the coefficient of friction or road surface condition is acquired.

Subsequently, the process proceeds to step S110, and as the vehicle body side determination, it is determined whether or not there is a change in the road surface state based on the information acquired in step S100. Thereafter, when the determination in step S110 is affirmative, the process proceeds to step S120, and the data communication unit 25 transmits vehicle body side information indicating that there is a change in the road surface state to each tire side device 1. And when a negative determination is carried out by step S110, a vehicle body side determination process is complete | finished, without transmitting vehicle body side information, and when a vehicle body side information is transmitted in step S120, a vehicle body side determination process is complete | finished after that.

On the other hand, in the tire side device 1 of each wheel, the control unit 11 executes the tire side determination process shown in FIG. 8 and the data transmission process shown in FIG. This process is performed every predetermined control cycle.

First, as shown in FIG. 8, the control unit 11 performs an input process of a detection signal of the acceleration acquisition unit 10 in step S200. This process is continued in the subsequent step S210 for a period until the tire 3 makes one revolution. Then, when the detection signal of the acceleration acquisition unit 10 is input for one rotation of the tire, the process proceeds to the subsequent step S220, and the feature value of the time axis waveform of the detection signal of the acceleration acquisition unit 10 for one rotation of the tire input as the current feature value. Extract The processes of steps S200 to S220 described above are performed by the feature amount extraction unit 11a of the control unit 11.

The fact that the tire 3 has made one rotation is determined based on the time axis waveform of the detection signal of the acceleration acquisition unit 10. That is, since the detection signal draws the time axis waveform shown in FIG. 4, one rotation of the tire 3 can be grasped by confirming the first peak value and the second peak value of the detection signal.

Further, it is the period before and after that including the “step-in area”, the “before kicking area”, and the “kicking area” that the road surface condition particularly appears as a change of the time axis waveform of the detection signal. Therefore, data in this period may be input, and data of all detection signals of the acceleration acquisition unit 10 during one rotation of the tire may not necessarily be input. For example, with regard to the “area before stepping in” and the “area after kicking out”, data in the vicinity of the “step-in area” or in the vicinity of the “kicking-out area” is sufficient. For this reason, in a region where the vibration level in the detection signal of the acceleration acquiring unit 10 is smaller than the threshold, it is detected as a period less susceptible to the road surface condition among the "pre-step-in region" and the "after kicking region". The signal may not be input.

The extraction of the feature amount performed in step S220 is performed by the method as described above.

Thereafter, the process proceeds to step S230, and the similarity is determined by the above-described method based on the current feature amount and the previous feature amount. For example, the similarity is compared with the threshold Th to determine whether there is a change in the road surface state. Determine if This process is executed based on the current feature amount extracted by the feature amount extraction unit 11a and the previous feature amount stored in the feature amount storage unit 11b in step S250 described later.

When an affirmative determination is made in step S230, the fact that there is a change in the road surface condition is stored in step S240. The process of steps S230 and S240 is performed by the change determination unit 11c of the control unit 11.

Finally, the process proceeds to step S250, the current feature amount is stored as the previous feature amount in the feature amount storage unit 11b, and the process is ended.

Further, the control unit 11 executes data transmission processing shown in FIG. First, in step S300, it is determined whether or not the tire side device 1 determines that there is a change in the road surface state. This determination is performed based on whether or not the change in the road surface state is stored in step S240 of FIG. 8 described above. If an affirmative determination is made here, the process proceeds to step S310, and if a negative determination is made, the process proceeds to step S320. Then, in step S310 or step S320, it is determined whether or not it is determined in the vehicle body side system 2 that there is a change in the road surface state. This determination is performed based on whether or not the vehicle body side information transmitted in step S120 of FIG. 7 described above is received.

Then, if an affirmative determination is made in step S310, the process proceeds to step S330, and data of “high reliability” is added to road surface data including data of the feature amount this time, and the data communication unit 12 is notified. If the determination is affirmative in step S320, the process proceeds to step S340, and data of “in reliability” is added to the road surface data including the data of the feature amount this time, and the data communication unit 12 is notified. Furthermore, when the negative determination is made in step S310, the process proceeds to step S350, and data of “reliability is low” is added to the road surface data including the data of the feature amount this time and transmitted to the data communication unit 12.

The case where an affirmative determination is made in step S310 is a case where it is determined that there is a change in the road surface condition in both the tire side device 1 and the vehicle body side system 2. Therefore, in this case, it can be said that the reliability of the determination that there is a change in the road surface condition is high. Therefore, the road surface data sent to the data communication unit 12 includes data “high reliability”.

Further, the case where the determination in step S320 is affirmed is the case where it is determined that the road surface state has been changed in the vehicle body side system 2 although the tire side device 1 has not been determined to have changed the road surface state. In this case, the reliability of the determination that there is a change in the road surface condition is relatively high, although this is not the same as the case where the positive determination is made in step S310. Therefore, the road surface data sent to the data communication unit 12 includes the data “in reliability”.

Furthermore, the case where the negative determination is made in step S310 is a case where it is determined that the road surface state has changed in the tire device 1, but the road surface state has not been determined in the vehicle body side system 2. In this case, although there may be a change in the road surface condition, it can be said that the reliability is relatively low. Therefore, the road surface data sent to the data communication unit 12 includes data of “reliability is low”.

Here, when it is determined that there is a change in the road surface condition only with the tire side device 1, "reliability is low", and when it is determined that there is a change in the road surface condition only with the vehicle body side system 2, "under reliability" ". However, since the level of reliability varies depending on the system specifications etc., it is better to compare the two and set the one with high reliability as “in reliability” and the one with low reliability as “low reliability”. .

As described above, when road surface data is transmitted from the transmission control unit 11 d to the data communication unit 12, the data communication unit 12 outputs the data to the receiver 21. Thereby, the road surface data from each tire side device 1 is received by the receiver 21. As described above, road surface data including the feature amount is transmitted from the data communication unit 12 only when there is a change in the road surface state, and data transmission is not performed when there is no change in the road surface state. I have to. Therefore, the communication frequency can be reduced, and power saving of the control unit 11 in the tire 3 can be realized.

Furthermore, in the receiver 21, the control unit 26 performs the road surface state estimation process shown in FIG. This process is performed every predetermined control cycle.

First, in step S400, data reception processing is performed. This process is performed by the control unit 26 taking in the road surface data when the data communication unit 25 receives the road surface data. When the data communication unit 25 is not receiving data, the control unit 26 ends the process without taking in road surface data.

Thereafter, the process proceeds to step S410, and it is determined whether data has been received. If it has been received, the process proceeds to step S420. If it has not been received, the processes of steps S400 and S410 are repeated until it is received.

Then, in step S420, the road surface state is estimated. The road surface state is estimated by comparing the current feature amount included in the received road surface data with the support vector classified by road surface type stored in the support vector storage unit 26a. For example, the feature amount is obtained as the similarity with all the support vectors for each type of road surface, and the road surface of the support vector having the highest similarity is estimated to be the current traveling road surface. The calculation of the degree of similarity at this time may use the same method as the calculation of the degree of similarity between the current feature amount and the previous feature amount performed in step S230 of FIG.

Further, as described above, since the data indicating the level of reliability is also attached to the data of the feature amount this time, the method of estimating the road surface state can be changed according to the reliability.

For example, each element of the matrix indicating the feature amount used for estimating the road surface condition also includes an element that becomes prominent on a dry road, an element that becomes prominent on a wet road surface, and an element that becomes prominent on a frozen road. For this reason, in the case of “high reliability”, the elements of all the matrices indicating the feature amounts included in the road surface data are not used to calculate the similarity, and among the elements, elements that become particularly prominent for each road surface Let's take out only and calculate the similarity. Further, in the case of “in reliability”, the number of elements is increased and the calculation of the similarity is performed as compared to the case of “in high reliability”. Then, in the case of “reliability is low”, calculation of similarity is performed using all elements of the determinant.

As described above, by changing the element used for the calculation of the degree of similarity based on the level of the reliability, the calculation of the degree of similarity can be performed by narrowing down the elements. For this reason, for example, as in the case of “high reliability”, it is also possible to estimate the road surface condition more accurately by taking out only the element that is particularly remarkable for each road surface. For example, in the vehicle body side system 2, when the road surface state is estimated to be dry before the road surface state changes, the road surface state after the change is either a wet road or a frozen road when the road surface state changes. It may not be clear which way it is. In this case, if the elements that become prominent in the wet path and the elements that become prominent in the freezing path are extracted and the similarity degree is calculated using only these elements, it will be a wet path more clearly It can be estimated if it is a freezing path.

Also, in this way, it is possible to estimate the road surface condition with a smaller amount of data according to the reliability. Therefore, the amount of data to be sent as road surface data can be changed from each tire-side device 1 according to the level of reliability, and the power necessary for data transmission can be further reduced, thereby further saving the cost. Power can be realized.

As described above, the road surface condition is estimated by the tire device 100 according to the present embodiment. When such a road surface state is estimated, transmission of road surface data including the present feature amount from the tire device 1 is performed only at the change timing of the road surface state. Specifically, the road surface data from the tire side device 1 is transmitted only at the timing when the tire side device 1 or the vehicle body side system 2 determines that there is a change in the road surface state. Therefore, the communication frequency can be reduced, and power saving of the control unit 11 in the tire 3 can be realized.

In addition, since the tire device 100 does not have to include the support vector storage unit for storing the support vector in the control unit 11 of the tire side device 1, memory saving of the control unit 11 in the tire 3 can be achieved. .

Furthermore, the data processing of similarity calculation by the control unit 11 of the tire-side device 1 may be performed only on the current feature amount and the previous feature amount, and on the similarity calculation of the current feature amount and all support vectors. It may be performed by the vehicle body side system 2. For this reason, it is possible to further suppress the consumption of the memory in the control unit 11 in the tire 3, and to realize memory saving.

Therefore, it becomes possible to set it as tire device 100 which can realize memory saving and power saving of control part 11 in tire 3, and tire device 100 containing it.

Further, not only when the tire side device 1 determines that there is a change in the road surface state, but also when the vehicle body side system 2 determines that there is a change in the road surface state, the road surface data from the tire side device 1 It is supposed to be sent. Therefore, even when the tire side device 1 can not grasp the change of the road surface state, the road surface data can be transmitted to the vehicle body side system 2, and the change of the road surface state can be recognized more accurately.

Furthermore, by including road surface data and data on reliability, it is possible to change the road surface condition estimation method according to the reliability. For example, it is also possible to estimate the road surface condition with a smaller amount of data according to the reliability. Therefore, the amount of data to be sent as road surface data can be changed from each tire-side device 1 according to the level of reliability, and the power necessary for data transmission can be further reduced, thereby further saving the cost. Power can be realized.

Second Embodiment
The second embodiment will be described. The present embodiment is different from the first embodiment in that it is possible to estimate the road surface condition in each tire side device 1 with respect to the first embodiment, and the other is the same as the first embodiment. Only the part will be described.

In the present embodiment, as shown in FIG. 11, a support vector storage unit 11e is provided instead of the feature storage unit 11b provided in the first embodiment, and the support vector storage unit 26a of the receiver 21 is eliminated. In addition, the tire side device 1 can be calculated by the change determination unit 11c calculating the degree of similarity between the current feature value extracted by the feature value extraction unit 11a and all the support vectors stored in the support vector storage unit 11e. In the above, it is possible to determine the change of the road surface condition. Then, when there is a change in the road surface state, data indicating the estimation result of the road surface state based on the calculation of the similarity is transmitted from the tire device 1 as road surface data.

On the other hand, in the receiver 21, the road surface data transmitted by the tire side device 1 is received, and the road surface state indicated by the road surface data is transmitted from the state estimation unit 26b to the brake ECU 22 and the notification device 23.

As described above, the tire side device 1 can be provided with the support vector storage unit 11 e so that the tire side device 1 can estimate the road surface state. Even in this case, it can be determined based on the estimation result whether or not there is a change in the road surface state. For this reason, when there is a change in the road surface condition in the tire side device 1 or when the vehicle body side information is transmitted from the vehicle body side system 2, the road surface data including the estimation result or the feature value of the road surface condition is transmitted. You can do so. Thereby, although the effect of the memory saving of the control unit 11 in the tire 3 can not be obtained, the same effect as that of the first embodiment can be obtained such that power saving can be realized.

Third Embodiment
A third embodiment will be described. In this embodiment, the tire side device 1 does not determine the change in the road surface state based on the feature amount with respect to the first embodiment, but determines the change in the road surface state based on the vehicle body side information transmitted from the vehicle body side system 2 Can only be done. The other parts of this embodiment are the same as those of the first embodiment, so only the parts different from the first embodiment will be described.

In the present embodiment, as shown in FIG. 12, the feature storage unit 11b provided in the first embodiment is eliminated. Further, the change determination unit 11 c can determine that there is a change in the road surface state based on the vehicle body side information sent from the vehicle body side system 2. Then, when there is a change in the road surface state, road surface data including the feature amount is transmitted from the tire side device 1.

On the other hand, when the receiver 21 determines that there is a change in the road surface state based on the information from the peripheral device 24, the receiver 21 transmits the vehicle body side information to the tire side device 1. Also, the receiver 21 receives the road surface data transmitted by the tire-side device 1, and from the state estimation unit 26b, the feature amount included in the road surface data and the support vector by road surface type stored in the support vector storage portion 26a. The road surface condition is estimated by comparing with. Then, the estimation result of the road surface state is transmitted from the state estimation unit 26 b to the brake ECU 22 and the notification device 23.

Specifically, first, in the vehicle body side system 2, as described in the first embodiment, by performing the vehicle body side determination process shown in the flowchart of FIG. 7, the determination of the change in road surface state based on the peripheral device 24 I do. If it is determined based on this that there has been a change in the road surface state, transmission of vehicle body side information indicating that fact is performed.

On the other hand, the tire side device 1 executes the tire side determination process shown in FIG. First, in steps S500 to S520, the same processes as steps S200 to S220 of the tire side determination process shown in FIG. 8 are executed. Then, in step S530, it is determined whether or not it is determined in the vehicle body side system 2 that there is a change in the road surface state. Here, it is positively determined that the vehicle body side information indicating that it is determined that there is a change in the road surface condition described above is transmitted from the vehicle body side system 2, and it is negatively determined that the vehicle body side information is not transmitted. If an affirmative determination is made here, the process proceeds to step S540, the road surface data of the present feature amount obtained in step S520 is transmitted to end the process, and when a negative determination is made, the process ends.

Thereafter, the road surface state estimation process shown in FIG. 10 is performed in the tire side device 1 so that the road surface state estimation based on the road surface data transmitted from the tire side device 1 is performed.

As described above, when it is determined that there is a change in the road surface state in the vehicle body side system 2, the vehicle body side information is transmitted to the tire side device 1, and the road surface data is transmitted from the tire side device 1 only in that case. You may do so.

In such a form, although the tire side device 1 can not determine that there is a change in the road surface state, it does not have to perform the determination, so that the memory saving of the control unit 11 in the tire 3 is further reduced. realizable. Further, since the road surface data can be requested to the tire side device 1 only when the vehicle body side system 2 requires the road surface data, data transmission of the tire side device 1 can be further restricted. Therefore, power saving of the control unit 11 of the tire side device 1 can be realized.

(Other embodiments)
The present disclosure has been described based on the above-described embodiment, but is not limited to the embodiment, and includes various modifications and variations within the equivalent range. In addition, various combinations and forms, and further, other combinations and forms including only one element, or more or less than these elements are also within the scope and the scope of the present disclosure.

For example, in the feature amount storage unit 11b, the feature amount one rotation before is stored as the feature amount at the time of the past rotation of the tire 3. However, the feature amount storage unit 11b does not necessarily have to be the feature amount one rotation before. That is, the feature amount storage unit 11b stores the feature amounts before multiple rotations as the past feature amounts without being limited to storing the feature amounts of the previous time as the feature amounts of the tire 3 in the past rotation (hereinafter referred to as past feature amounts). Alternatively, the average value of the past feature amounts for a plurality of rotations may be stored. Then, for the calculation of the degree of similarity with the previous feature value, the previous feature value among the past feature values may be used, or an average value of a plurality of past values including the previous feature value may be used. However, from the viewpoint of memory saving, it is preferable to store only as few feature quantities as possible.

In the above embodiment, although the case where the vibration detection unit is configured by the acceleration acquisition unit 10 is illustrated, the vibration detection unit can also be configured by an element that can perform other vibration detection, such as a piezoelectric element.

In addition, when there is a change in the road surface state, the road surface data including the feature amount this time is transmitted from the tire device 1. However, the previous feature amount may be included in the road surface data. In that case, in the vehicle body side system 2, the road surface condition before the change can also be estimated by comparing the previous feature quantity with the support vector. Therefore, it is possible to estimate both of the road surface condition before and after the change and to more accurately recognize the change of the road surface condition.

Further, in the above embodiment, the control unit 26 of the receiver 21 provided in the vehicle body side system 2 obtains the similarity between the current feature amount and the support vector to estimate the road surface state. However, this is only an example, and the similarity may be determined or the road surface state may be estimated by another ECU, for example, the control unit of the brake ECU 22.

Moreover, although the tire side apparatus 1 was provided with respect to each of the some tire 3 in said each embodiment, what is necessary is just to be provided in at least one.

Claims (9)

1. A tire side device (1) arranged in a tire (3) and transmitting road surface data which is data relating to a road surface state, and a vehicle side system arranged in a vehicle side and receiving the road surface data to estimate the road surface state A road surface state estimation device having (2), wherein
   The tire side device is
   A vibration detection unit (10) that outputs a detection signal according to the magnitude of the vibration of the tire; a first control unit (11) that creates the road surface data based on the detection signal; and the vehicle body side system A first transmission / reception unit (12) for performing data communication between the
   The body side system is
   The peripheral device (24) for acquiring information related to the road surface state, the second transmitting / receiving unit (25) performing data communication with the tire side device, and the information based on the information related to the road surface state acquired by the peripheral device When it is determined that there is a change in the road surface state, the second transmitting / receiving unit transmits the vehicle body side information indicating that the road surface state has changed to the tire device, and the second transmitting / receiving unit receives A second control unit (26) for estimating the road surface state based on the road surface data as described above;
   Furthermore, it is determined that the road surface state has changed in the change determination portion (11c) in which the first control portion determines that the road surface state has changed based on the detection signal, and the change determination portion And a transmission control unit (11d) that causes the first transmission / reception unit to transmit the road surface data when vehicle body side information is received.
2. The first control unit includes a feature extraction unit (11a) that extracts a feature of the detection signal during one rotation of the tire and creates the road surface data including the feature.
   The change determination unit uses the feature amount extracted at the current rotation of the tire by the feature amount extraction unit as the current feature amount, and the current feature amount and the past feature amount stored in the feature amount storage unit. Determine that the road surface condition has changed based on
   The road surface state estimation device according to claim 1, wherein the transmission control unit transmits the road surface data including the current feature amount.
3. The road surface state estimation device according to claim 2, wherein the change determination unit calculates the degree of similarity between the current feature amount and the past feature amount, and determines that the road surface state has changed based on the degree of similarity.
4. The feature storage unit stores the previous feature, which is the feature before one rotation extracted by the feature extraction unit, as the past feature.
   The road surface state estimation device according to claim 2 or 3, wherein the change determination unit determines that the road surface state has changed based on the current feature amount and the previous feature amount.
5. The first control unit changes the road surface condition when both of the case where the change determination unit determines that the road surface condition has changed and the case where the vehicle body side information is received are satisfied. The road surface data includes data indicating that the road surface data is highly reliable, and the road surface data includes data indicating that the reliability is lower in the case of either one than in the case where both are satisfied. The road surface state determination device according to any one of 1 to 4.
6. A tire side device (1) arranged in a tire (3) and transmitting road surface data which is data relating to a road surface state, and a vehicle side system arranged in a vehicle side and receiving the road surface data to estimate the road surface state A road surface state estimation device having (2), wherein
   The tire side device is
   A vibration detection unit (10) that outputs a detection signal according to the magnitude of the vibration of the tire; a first control unit (11) that creates the road surface data based on the detection signal; and the vehicle body side system A first transmission / reception unit (12) for performing data communication between the
   The body side system is
   The peripheral device (24) for acquiring information related to the road surface state, the second transmitting / receiving unit (25) performing data communication with the tire side device, and the information based on the information related to the road surface state acquired by the peripheral device When it is determined that there is a change in the road surface state, the second transmitting / receiving unit transmits the vehicle body side information indicating that the road surface state has changed to the tire device, and the second transmitting / receiving unit receives A second control unit (25) for estimating the road surface state based on the road surface data as described above;
   The road surface state estimation device according to claim 1, wherein the first control unit transmits the road surface data from the first transmission / reception unit to the vehicle body system when the first transmission / reception unit receives the vehicle body-side information.
7. The first control unit includes a feature extraction unit (11a) that extracts a feature of the detection signal during one rotation of the tire and creates the road surface data including the feature.
   The road surface state estimation device according to claim 6, wherein the transmission control unit transmits the road surface data including the current feature amount.
8. The road surface state estimation apparatus according to any one of claims 2 to 4, wherein the feature quantity extracted by the feature quantity extraction unit is represented by a feature vector of a time axis waveform of the detection signal.
9. The second control unit stores a support vector storage unit (26a) storing the support vector of the feature amount for each type of the road surface state, the current feature amount included in the road surface data, and the support vector storage unit The road surface state estimation device according to any one of claims 2 to 4, 7 and 8, further comprising: a state estimation unit (26b) that estimates the road surface state based on the support vector.

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