WO2019093437A1 - Road surface condition assessing device - Google Patents

Abstract

When a road surface condition is to be assessed, turning on a startup switch (30) causes a connection to be established between a tire side device (1) and a vehicle body side system (2), and data communication is performed. Then, when the startup switch (30) is turned off, a disconnection request signal is transmitted from the vehicle body side system (2) to the tire side device (1). As a result, the tire side device (1) can also recognize that the startup switch (30) has been turned off. The tire side device (1) can therefore be prevented from attempting to maintain the connection even after the startup switch (30) has been turned off, thereby making it possible to disconnect the connection at the tire side device (1) to reduce power consumption.

Description

Road surface condition determination device Cross-reference to related applications

This application is based on Japanese Patent Application No. 2017-217113 filed on Nov. 10, 2017 and Japanese Patent Application No. 2018-187775 filed on June 22, 2018, which are incorporated herein by reference. The contents of the description are incorporated by reference.

The present disclosure detects the vibration received by the tire with the tire side device, creates road surface data indicating the road surface state based on the vibration data, transmits it to the vehicle body side system, and determines the road surface state based on the road surface data. The present invention relates to a road surface state determination device.

Conventionally, in Patent Document 1, there is provided a road surface state determining method including an acceleration sensor on the back surface of the tire tread, detecting the vibration applied to the tire by the acceleration sensor, and determining the road surface state based on the detection result of the vibration. Proposed. In this road surface condition determination method, a 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. , Determine 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 type of road surface having the highest degree of similarity, such as dry road surface, wet road surface, frozen road, snow road etc., is currently running. It is determined that the road surface condition is According to such a road surface state determination method, it is possible to perform road surface determination with high robustness.

JP, 2016-107833, A

When determining the road surface state by the road surface state determining method as described above, it is necessary to transmit data for determining the road surface state from the tire side device to the vehicle body side system, but the power consumption for data transmission is large. However, since the tire side device is provided at a position physically separated from the vehicle body side system, it is required to reduce the power consumption in the power supply unit. In particular, when a battery is used as a power supply unit, battery replacement is not easy and reduction of power consumption is required.

An object of the present disclosure is to provide a road surface state determination device capable of reducing power consumption of a tire side device.

The road surface state determining device according to one aspect of the present disclosure includes a tire side device disposed in the tire and a vehicle body side system disposed on the vehicle body side, and the tire side device performs detection according to the magnitude of tire vibration. The vehicle body side system includes a vibration detection unit that outputs a signal, a first control unit that creates road surface data based on the detection signal, and a first transmission / reception unit that performs data communication with the vehicle body side system A second transmitting / receiving unit for performing data communication with the tire-side device, determination of a road surface state based on road surface data received by the second transmitting / receiving unit, and determination of an on / off state of an activation switch for making the vehicle startable When the activation switch is switched from off to on, the communication connection between the first transmission / reception unit and the second transmission / reception unit is established, and the activation switch is switched from on to off It has a configuration having a second control unit for transmitting a disconnection request signal instructing the disconnection from the second transceiver to the tire side unit.

As described above, when the start switch is turned off, the vehicle body system transmits a disconnection request signal to each tire device. Since each tire side device is provided inside the tire, the on / off state of the start switch can not be grasped, but each tire side can be detected by sending a cutting request signal from each vehicle side system to each tire side device. The device can also know that the start switch has been turned off. Therefore, it is possible to suppress each tire side device from trying to maintain the connection even after the start switch is switched off, and the connection can be disconnected in each tire side device. As a result, the road surface state determination device can be achieved that can reduce the power consumption of the tire side device.
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 a figure showing the block configuration in the vehicles mounting state of the tire device to which the tire side device concerning a 1st embodiment was applied. It is the block diagram which showed the detailed composition of the tire side device and the 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 process which the control part of a vehicle body side system performs. It is a flowchart of the tire side process which the control part of a tire side apparatus performs. It is a flowchart of the tire side process which the tire side apparatus with which the tire apparatus concerning 2nd embodiment is equipped performs.

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 determination function according to the present embodiment will be described with reference to FIGS. 1 to 8. The tire device 100 according to the present embodiment determines 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. As the vehicle body side system 2, a receiver 21, an electronic control unit for brake control (hereinafter referred to as a brake ECU) 22, a notification unit 23 and the like are provided. The part of the tire device 100 that realizes the road surface state determination function corresponds to the road surface state determination device. In the case of this embodiment, the receiver 21 of the tire side device 1 and the vehicle body side system 2 constitutes a road surface state determining 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 To determine the Specifically, the tire side device 1 transmits road surface data when it is determined that the road surface state has changed. The receiver 21 receives road surface data sent when there is a change in the road surface condition, and the road surface condition is determined based on the received road surface data.

In addition, the tire device 100 transmits the determination result of the road surface condition in the receiver 21 to the notification device 23, and causes the notification device 23 to notify the determination 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 an acceleration acquisition unit 10, a control unit 11, a data communication unit 12, a power supply unit 13 and a start control unit 14. As shown, it is provided on the back side of the tread 31 of the tire 3.

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 or the like 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 extraction unit 11a, a feature storage unit 11b, a change determination unit 11c, and a communication 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). Further, the feature amount extraction unit 11a transmits data including the extracted feature amount to the data communication unit 12 as road surface data through the communication 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. 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 communication control unit 11d.

The communication control unit 11 d controls communication with the vehicle body side system 2 through the data communication unit 12. Specifically, the communication control unit 11 d controls connection for performing two-way communication with the receiver 21, that is, control of establishment and disconnection of a dedicated communication path, and control of data communication through the data communication unit 12. Do.

The communication control unit 11 d detects that the tire 3 has rotated, that is, that the vehicle has traveled, based on, for example, the output voltage waveform of the detection signal of the acceleration acquisition unit 10 input to the feature extraction unit 11 a. A method of detecting that the vehicle has traveled will be described later. Then, when the vehicle starts traveling, the communication control unit 11 d performs processing for establishing a connection with the receiver 21 and disconnects the connection based on the disconnection request signal from the receiver 21. Further, when the communication control unit 11 d transmits a control signal indicating that there is a change in the road surface condition from the change determination unit 11 c after establishing the connection, the feature amount extraction unit 11 a extracts it at that time. Road surface data including the feature amount this time is transmitted to the data communication unit 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 communication 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 communication 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 data communication unit 12 receives a disconnection request signal instructing disconnection of the connection from the data communication unit 25, the data communication unit 12 receives it and transmits it to the communication control unit 11d. Thus, the communication control unit 11 d disconnects the communication connection with the receiver 21 based on the received disconnection request signal.

Note that unique identification information (hereinafter referred to as ID information) is assigned to each tire-side device 1. Therefore, each tire-side device 1 can identify whether it is an instruction signal for itself based on the ID information attached to the disconnection request signal. Therefore, when the data communication unit 12 receives an instruction signal such as a sleep instruction signal to which its own ID information is attached, the data communication unit 12 transmits a signal indicating the content to the communication control unit 11 d.

The power supply unit 13 is a power supply of the tire-side device 1 and supplies the power to the respective components provided in the tire-side device 1 so that the respective components can be operated. The power supply unit 13 is configured of, for example, a battery such as a button battery. Since the tire side device 1 is provided in the tire 3, battery replacement can not be easily performed, and therefore, it is necessary to reduce power consumption. In addition to the battery, the power supply unit 13 can also be configured by a power generation device, a storage battery, and the like. When the power supply unit 13 is configured to have a power generation device, the problem of battery life is reduced as compared to the case where it is a battery, but large power generation is difficult, so the problem of reducing power consumption is the battery The same as in the case of
The activation control unit 14 controls activation and sleep of the functions of the units of the tire-side device 1. Here, although the start control unit 14 is illustrated as a configuration separate from the control unit 11, the start control unit 14 may be built in the control unit 11. Specifically, the activation control unit 14 switches to the activated state based on the detection signal of the acceleration acquiring unit 10, and switches to the sleep state when the connection with the receiver 21 is disconnected as described later. Do. In the activation state, each function of the acceleration acquisition unit 10, the control unit 11, the data communication unit 12, and the activation control unit 14 is activated based on the power supply from the power supply unit 13. In the sleep state, the control unit 11 and the data communication unit 12 are put to sleep. The activation control unit 14 receives the detection signal of the acceleration acquisition unit 10, detects the rotation of the tire 3, that is, the traveling of the vehicle based on the waveform of the detection signal exceeding a predetermined threshold, and detects the traveling of the vehicle. Switch each part that was sleeping to the activated state. For example, the detection signal of the acceleration acquisition unit 10 is the output voltage or output current of the acceleration acquisition unit 10, and when the voltage or current input to the activation control unit 14 exceeds a predetermined threshold, the activation control unit 14 Start up. Further, when the connection is disconnected, the activation control unit 14 switches the activated control unit 11 and the data communication unit 12 to the sleep state.

As a result, when a part of the tire side device 1, here, the control unit 11 and the data communication unit 12 are in the sleep state, the power consumption in these is eliminated, so the power consumption in the tire side device 1 can be reduced. It will be possible.

In the tire side device 1, the sleep state is the part that realizes various arithmetic functions such as waveform processing and data transmission function, and the acceleration acquisition unit 10 and the activation control unit 14 do not enter the sleep state. Power is consumed. However, since a part that realizes various arithmetic functions such as waveform processing that consumes a large amount of power and a data transmission function is put in the sleep state, it is effective for reducing power consumption.

On the other hand, when the start switch 30 shown in FIG. 2 is turned on, the receiver 21 and the brake ECU 22 and the notification device 23 constituting the vehicle body side system 2 are operated based on the power supply from the battery 40. Also, basically, when the start switch 30 is turned off, the power supply from the battery 40 is turned off and the operation is stopped. However, as for the receiver 21, even if the start switch 30 is turned off, the power supply from the battery 40 is continued for a predetermined time, or the receiver 21 can be operated for a predetermined period using power stored in a capacitor (not shown). It has become. In addition, about predetermined time which continues the electric power supply from the battery 40, it should just be set to the time which can transmit the cutting | disconnection request signal mentioned later with allowances. In the case of this embodiment, the order is determined so that the power supply from the battery 40 or the like to the receiver 21 is stopped after it is confirmed that the disconnection request signal is issued. Therefore, the power supply to the receiver 21 is continued until the disconnection request signal is transmitted, and the power supply to the receiver 21 is stopped after the transmission of the disconnection request signal.

The receiver 21 is configured to have a data communication unit 25 and a control unit 26 as shown in FIG.

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. 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 an on / off determination unit 26a, a communication control unit 26b, a support vector storage unit 26c, and a road surface determination unit 26d as functional units that perform various processes.

The on / off determination unit 26a receives a switch signal indicating the on / off state of the start switch 30 in the vehicle, that is, the switch for making the vehicle ready to start, such as an ignition switch, and turns on or off the start switch 30 based on the switch signal. Determine Then, the on / off determination unit 26a notifies the communication control unit 26b that the activation switch 30 has been switched from off to on or has been switched from on to off. The on / off determination unit 26a is not activated since the power supply to the receiver 21 is not performed before the activation switch 30 is turned on. However, the activation switch 30 is turned on to transmit power to the receiver 21. It operates when the supply is done. Therefore, the on / off determination unit 26a determines that the activation switch 30 is switched from off to on based on the switch signal immediately after the start of operation. Further, in the case of the present embodiment, the receiver 21 is configured to be activated for a predetermined time even after the activation switch 30 is switched from on to off, so the activation switch 30 is turned on based on the switch signal. It is determined that the switch has been switched off.

When the activation switch 30 is switched from off to on, the communication control unit 26 b performs processing for establishing a communication connection with each tire-side device 1. Further, when the activation switch 30 is switched from on to off, the communication control unit 26 b transmits a disconnection request signal to the data communication unit 25 in order to disconnect the communication connection with each tire-side device 1. Output control signal. Based on this, a disconnection request signal is transmitted from the data communication unit 25, and the connection of communication with each tire-side device 1 is disconnected.

The support vector storage unit 26c 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 road surface determination unit 26 d 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 c. Determine 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 determined as the current traveling road surface.

In addition, when the road surface determination unit 26d determines the road surface state, the control unit 26 transmits the determined 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 condition determined through the notification device 23 may be always displayed, or the road surface condition is determined only when the driving needs to be performed more carefully, such as a wet route or a frozen route. 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 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 that. 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 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 the present 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. For this reason, the distance between the coordinates indicated by the feature vectors Xi of the sections 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 8.

First, an operation when the driver starts the traveling by turning on the start switch 30 while the vehicle is stopped and then the vehicle stops and the driver turns off the start switch 30 will be described.

In the vehicle body side system 2, the control unit 26 of the receiver 21 executes the vehicle body side processing shown in FIG. This process is executed every predetermined control cycle when the power supply from the battery 40 is performed by turning on the start switch 30 and the receiver 21 and the like are started. On the other hand, in each tire side device 1, the tire side process shown in FIG. 8 is performed. In addition, below, each process of FIG. 7 and FIG. 8 is demonstrated in order according to a time series.

First, when the start switch 30 is turned on, the power supply from the battery 40 is performed to start the receiver 21 and the like, and when the vehicle body side process shown in FIG. 7 is performed, the control unit 26 performs step S100. It is determined whether or not the connection is in progress. Immediately after the receiver 21 is activated, the connection is not yet in progress, so the process proceeds to step S105. If the connection is in progress based on the processing described later, the process proceeds to step S120.

In step S105, the control unit 26 determines whether the scanning cycle has come. The scanning is a process of reading data transmitted from the tire-side device 1. The control unit 26 repeatedly performs scanning at predetermined scanning cycles, and the process is repeated when negative determination is made in step S105, and the process proceeds to step S110 when positive determination is made.

On the other hand, in each tire-side device 1, when the vehicle starts traveling and, for example, the output voltage of the detection signal of the acceleration acquisition unit 10 exceeds a predetermined threshold, the activation control unit 14 activates the control unit 11 or the data communication unit 12. Let Thereby, the tire side process shown in FIG. 8 is performed.

First, in step S200, the control unit 11 determines whether the vehicle is traveling. This process is performed based on the detection signal of the acceleration acquisition unit 10. For example, when the output voltage waveform of the detection signal indicates a waveform for one rotation of the tire, it is determined that the vehicle is traveling. 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. In addition, since the rotation of the tire 3 is in agreement with the traveling of the vehicle, it can be detected based on the rotation of the tire 3 whether the vehicle is traveling or being stopped.

Here, when the vehicle starts traveling or when traveling is continued, an affirmative determination is made to proceed to step S205, and when a negative determination is made, the process of step S200 is repeated. When the vehicle starts traveling, the control unit 11 and the like are activated in the activation control unit 14 and the tire-side process is executed. Therefore, when the tire-side process is executed, that is, the vehicle travels. I agree that I started. For this reason, the process of this step may be omitted, and the process of the next step S205 may be performed. However, even if a voltage exceeding the threshold in noise is input to the activation control unit 14, the tire-side process can be executed, and the control unit 11 and the data communication unit 12 can be left in the sleep state. In such a case, it is preferable to execute the process of step S200.

Next, in step S205, it is determined whether connection is in progress. At this stage, since the connection is not yet performed, the determination in this process is negative and the process proceeds to step S210. However, when the connection is formed in step S225 described later, the process is positively determined and the process proceeds to step S230.

In the subsequent step S210, transmission processing of the advertisement signal is performed. By this processing, each tire-side device 1 is in a reception standby state so as to be able to receive a connection request signal to be described later, which will be sent from the vehicle-body-side system 2 later, after transmitting the advertisement signal. The advertisement signal is a signal serving as a keyword used when establishing a connection between the tire-side device 1 and the receiver 21, and is a signal for requesting the receiver 21 to transmit a connection request signal. For example, when BLT communication is applied as bi-directional communication, the advertisement signal is a 2.4 GHz frequency band, and transmission is performed multiple times in a short cycle. The advertisement signal includes ID information so that it can be confirmed that the signal is from the tire-side device 1 of the own vehicle.

Further, returning to the vehicle body side processing of FIG. 7, in step S <b> 110, the control unit 26 determines whether or not the advertisement signal from each tire-side device 1 has been received. As described above, when the advertisement signal is transmitted from each tire-side device 1, the advertisement signal from all of the four tire-side devices 1 is received by the receiver 21, and an affirmative determination is made in step S110, and the process proceeds to step S115. move on. Note that, basically, when the advertisement signal from all the four tire side devices 1 is received, the control unit 26 makes an affirmative determination in step S110. However, since it is only necessary to obtain road surface data from at least one tire side device 1 when determining the road surface state, if an advertisement signal from at least one tire side device 1 is received, an affirmative determination is made in step S110. You may

Then, in step S115, a connection request signal for establishing a connection with each tire-side device 1 is transmitted. The connection request signal is an instruction signal for causing each tire-side device 1 to perform a process of establishing a connection, and is a signal including an ID signal of the corresponding tire-side device 1. By executing this process, a connection request signal is transmitted to each tire-side device 1 through the data communication unit 25. Since a connection is established by this processing, a flag indicating the connection is set, and thereafter it is determined that the connection is in progress in the determination of step S100.

On the other hand, in the tire-side process of FIG. 8, in step S215, the control unit 11 enters a data waiting state to receive the connection request signal. Then, as described above, if the connection request signal is transmitted from the receiver 21, an affirmative determination is made in step S220, and the process proceeds to step S225 to form a connection. As a result, a dedicated communication path is formed between each tire-side device 1 and the receiver 21 and communication is possible even with large-volume data.

Thereafter, the process proceeds to step S230, and it is determined whether a disconnection request signal has been received. In this process, a disconnection request signal is transmitted from the receiver 21 in step S140 of FIG. 7 described later, and it is positively determined that this is received, but a disconnection determination signal is not transmitted here because it is not yet transmitted. Be done. Therefore, the process proceeds to step S235, and the input processing of the detection signal of the acceleration acquisition unit 10 is performed. This process is continued in the subsequent step S240 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 S245, 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 fact that the tire 3 has made one rotation can be determined based on the method described above.

It should be noted that the road surface state appears as a change in the time axis waveform of the detection signal particularly in the period before and after that including the "step-in area", the "before kicking area", and the "kicking area". 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.

Further, the extraction of the feature amount performed in step S245 is performed by the method as described above.

Thereafter, the process proceeds to step S250, 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 value Th to determine whether there is a change in the road surface condition. 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 S260 described later.

When an affirmative determination is made in step S250, data transmission processing is performed in step S255. That is, the communication control unit 11 d transmits road surface data including the feature amount this time to the data communication unit 12. As a result, road surface data including the feature amount this time is transmitted from the data communication unit 12. 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.

Further, the process proceeds to step S260, the current feature amount is stored as the previous feature amount in the feature amount storage unit 11b, and the process is ended. After this, each process from step S200 is executed again every predetermined control cycle. Since the connection is already in progress, the process of steps S210 to S225 for establishing the connection is omitted and the feature quantity is extracted, and the road surface data including the feature quantity is the car body every time there is a change in the road condition. It will be transmitted to the side system 2.

On the other hand, in the vehicle body side process of FIG. 7, in step S120, the control unit 26 determines whether or not the start switch 30 has been switched off, and proceeds to step S125 if it has not been switched off.

In step S125, 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 S130, where the control unit 26 determines whether data has been received. If it has been received, the process proceeds to step S135. If it has not been received, the process of each step is performed until reception. Is repeated.

Then, in step S135, the control unit 26 determines the road surface state. The determination of the road surface state is performed 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 26c. 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 determined as the current road surface. The calculation of the similarity at this time may be performed using the same method as the calculation of the similarity between the current feature and the previous feature performed in step S250 of FIG.

When it is determined that the start switch 30 is switched off in step S120 by turning off the start switch 30 after the driver has stopped, the process proceeds to step S140. Then, in step S140, a disconnection request signal for disconnecting the connection with each tire-side device 1 is transmitted. The disconnection request signal is an instruction signal for causing the tire-side device 1 to perform the process of disconnecting the connection, and is a signal including the ID signal of the corresponding tire-side device 1. By executing this process, a disconnection request signal is transmitted to each tire-side device 1 through the data communication unit 25. Note that since the connection is disconnected by this processing, it is determined that the connection is not in progress in the determination of step S100 thereafter.

Thereafter, the process proceeds to step S145, the power supply from the battery 40 or the like to the receiver 21 is stopped, the power of the receiver 21 is also turned off, and the vehicle body side process is ended.

When the disconnection request signal is transmitted, in the tire-side process of FIG. 8, it is determined in step S230 that the disconnection request signal has been received, and the process proceeds to step S265. Then, in step S265, after each tire device 1 transmits a disconnection request signal to the other tire device 1 other than itself, it proceeds to step S270 and disconnects the data communication itself. As a result, the connection is disconnected, and the control unit 11 and the data communication unit 12 are switched to the sleep state by the activation control unit 14, and the tire-side process is ended.

As described above, since the connection is disconnected when the start switch 30 is turned off, power consumption can be reduced. Further, in addition to disconnection of the connection, since the control unit 11 and the data communication unit 12 are put into the sleep state, power consumption can be further reduced.

Further, in each tire-side device 1, the disconnection request signal is transmitted to the other tire-side device 1 when disconnecting the connection, so that all the tire-side devices 1 can disconnect the connection more reliably. . For example, when the disconnection request signal is transmitted from the receiver 21, it does not necessarily reach all the tire side devices 1. That is, there is also a possibility that one of the tire side devices 1 is at the position of Null where radio waves from the receiver 21 are difficult to reach. Therefore, it is possible to disconnect the connection between each tire-side device 1 and the receiver 21 more reliably by adding the processing of sending a disconnection request signal from each tire-side device 1 to the other tire-side devices 1 Become.
When each tire side device 1 transmits a cutting request signal to other tire side devices 1 other than itself, each tire side device 1 grasps ID information of the other tire side devices 1. It is preferable to transmit the disconnection request signal including the ID information of the other tire-side device 1. By doing this, each tire side device 1 can grasp that it is the disconnection request signal sent to itself based on the ID information included in the disconnection request signal. That is, each tire side device 1 can determine whether the cutting request signal is sent from the tire side device 1 of the own vehicle or from the tire side device 1 of the other vehicle. Since the receiver 21 stores ID information of all the tire side devices 1 of the own vehicle, the receiver 21 transmits ID information of the other tire side devices 1 of the own vehicle to each tire side device 1 If it is made to memorize, ID information of other tire side devices 1 can be grasped to each tire side device 1. As described above, by including the ID information of the tire-side device 1 of the own vehicle when making a disconnection request, the connection is not erroneously disconnected by the disconnection request signal from the tire-side device 1 of the other vehicle. it can.

In addition, it is not essential to send a cutting | disconnection request | requirement signal with respect to the other tire side apparatus 1 from each tire side apparatus 1, and each tire side apparatus 1 may just cut a connection. Further, in the case of performing communication of large volume data with each tire side device 1, a connection is established in advance. However, if only the disconnection request signal is transmitted, the amount of data required is small, so there is no need to establish a connection, and the reception mode is set so that data from the other tire-side device 1 can be received. You should save.
As described above, the determination of the road surface state by the tire device 100 according to the present embodiment is performed. When the road surface condition is determined, when the start switch 30 is turned on, connections are established between the tire side devices 1 and the vehicle body side system 2 to perform data communication. Then, when the start switch 30 is switched off, the vehicle body side system 2 transmits a disconnection request signal to each tire side device 1.

Since each tire-side device 1 is provided inside the tire 3, it can not grasp the on / off state of the start switch 30, and therefore, tries to maintain the connection. However, when the start switch 30 is turned off, the start switch 30 is turned off also in each tire side device 1 by sending a disconnection request signal from the vehicle body side system 2 to each tire side device 1 using two-way communication. Know what happened. Therefore, it is possible to suppress each tire side device 1 from trying to maintain the connection even after the start switch 30 is switched off, and the connection can be disconnected in each tire side device 1. As a result, the tire device 100 including the road surface state determination device capable of reducing the power consumption of the tire side device 1 can be obtained.

In addition, when the start switch 30 is turned off, each tire-side device 1 not only disconnects the connection but puts the control unit 11 and the data communication unit 12 in the sleep state. As a result, the power consumption of the tire-side device 1 can be further reduced.

Also, with regard to the timing of transmitting road surface data from each tire side device 1, transmission of road surface data including the present feature value from the tire side device 1 is made to be only 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 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.

Second Embodiment
The second embodiment will be described. The present embodiment is the same as the first embodiment in that each tire side device 1 enables the disconnection of the connection based on its own determination with respect to the first embodiment, and the other is the same as the first embodiment. Only the differences from the form will be described.

The configuration of the tire device 100 including the tire side device 1 and the vehicle body side system 2 of the present embodiment is the same as that of the first embodiment, but executed by the control unit 11 of the tire side device 1 and the control unit 26 of the receiver 21 The process to do is different.

Specifically, as shown in FIG. 9, the control unit 11 determines in step S200 whether or not the vehicle is traveling, that is, determines whether the vehicle is traveling or being stopped, as shown in FIG. If it is determined, the process proceeds to step S275. Then, in step S275, it is determined whether a predetermined time has elapsed. The predetermined time here is set to a time longer than a stopping time at a traffic light or the like, that is, a time when it is assumed that the driver has finished driving. Then, until the predetermined time elapses, the processing of step S200 is repeated to measure time. For example, a counter which is incremented each time a negative determination is made in step S275 is provided, and when a count value of the counter reaches a predetermined value, it is determined that a predetermined time has elapsed, and when a positive determination is made in step S275 Make the value reset. This makes it possible to determine that a predetermined time has elapsed since the vehicle was stopped. Then, when a predetermined time has elapsed since the vehicle stopped, the processes of steps S265 and S270 are executed.

As described above, the tire side device 1 detects that the vehicle has stopped and does not stop at a traffic light or the like, and disconnects the connection by itself when it is assumed that the driver has finished driving. And the data communication unit 12 can be put to sleep. As a result, even if the disconnection request signal from the receiver 21 may not reach the tire-side device 1, the tire-side device 1 can reliably disconnect itself by itself.

However, even in a situation where the driver continues to stop the vehicle without turning off the start switch 30 for a long time and then resumes the traveling of the vehicle, the tire device 1 may cut off the connection by itself. Therefore, in the case of the present embodiment, when it is determined in step S100 of FIG. 7 whether or not the connection is in progress, the control unit 26 checks the state of the actual connection with each tire-side device 1 and Make a decision based on that. As described above, if it is determined in step S100 whether or not the connection is in progress by checking the actual connection status, even if the tire-side device 1 itself disconnects the connection, the determination in step S100 is negative. It is judged. As a result, by performing the processes of steps S105 to S115, it is possible to reconstruct the connection.

(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.

(1) For example, in each of the above embodiments, the case where the vibration sensor unit 1a constituting the vibration detection unit is constituted by an acceleration sensor is exemplified, but other elements capable of detecting vibration, for example, piezoelectric elements etc. You can also

(2) Moreover, in each said embodiment, the data containing a feature-value is used as road surface data which show the road surface state which appears in the detection signal of the vibration sensor part 1a from the tire side apparatus 1. FIG. However, this is also merely an example, and other data may be used as road surface data. For example, integrated value data of vibration waveforms of each of the five regions R1 to R5 included in vibration data during one rotation of the tire 3 may be road surface data, or raw data of the detection signal itself may be road surface data.

(3) Further, in each of the above-described embodiments, in order to reduce the power consumption of the tire side device 1, the road surface data is transmitted when there is a change in the road surface state. However, this is also merely an example, and the road surface data may be transmitted at another timing. For example, regardless of a change in the road surface condition, the road surface data may be transmitted every time the tire 3 makes one rotation or a predetermined rotation, or at predetermined time intervals.

(4) Also, the determination of the change in the road surface condition is not based on the similarity between the current feature amount and the previous feature amount as described above, but the feature at the time of rotation of the tire 3 in the past including the previous feature amount It can also be performed based on an amount (hereinafter, past feature amount).

For example, in the feature amount storage unit 11b, as the feature amount at the time of the past rotation of the tire 3, not only the feature amount of one rotation before but also the feature amount of one rotation before are stored. That is, not only the previous feature amount is stored as the past feature amount in the feature amount storage unit 11b, but the feature amount before multiple rotations is saved as the past feature amount, or the average value of the past feature amounts of multiple rotations is saved. To Then, for calculation of the degree of similarity with the previous feature amount, the previous feature amount of the past feature amounts is used, or an average value of a plurality of past values including the previous feature amount is used. Thus, the change in the road surface condition may be determined.

Further, not only when the change of the road surface state is determined based on the similarity of the feature amount, the change of the road surface state may be determined by other various methods.

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 state before the change can also be determined by comparing the previous feature amount with the support vector. Therefore, it is possible to determine both the road surface condition before and after the change, and to more appropriately recognize the change in the road surface condition.

(5) Further, in each of the above embodiments, 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 determine the road surface state. However, this is only an example, and the similarity may be determined by another ECU, for example, the control unit of the brake ECU 22, or the road surface state may be determined. Each process such as the determination of the state may be executed. That is, the same function as the control unit 26 may be played somewhere in the vehicle body side system 2.

Furthermore, the tire side device 1 is provided with a support vector storage unit so that the tire side device 1 can determine the road surface state, and the receiver 21 receives road surface data indicating the determination result and reads the road surface data. The determination of the road surface condition may be performed.

(6) In each of the above-described embodiments, when the vehicle starts traveling, the tire device 1 transmits an advertisement signal, and the receiver 21 having received the signal transmits a connection request signal to communicate between the two. Connection is to be established. However, this is also just an example, and various methods for establishing communication connection can be applied. For example, when the activation switch 30 is turned on, an advertisement signal may be sent from the receiver 21 side, and a connection request signal may be transmitted from the tire side devices 1 to the receiver 21 side to establish a connection. However, in such a case, it is necessary to perform scanning at each scanning cycle so that each tire-side device 1 can receive the advertisement signal, so from the viewpoint of reducing power consumption, the embodiment described above is used. Is preferred.

(7) In each of the above embodiments, the vehicle body side system 2 is provided with an external communication device capable of communicating with a communication center (not shown), and travels using data indicating the determination result of the road surface condition in the control unit 26 as the determination result data. It may be transmitted to the communication center together with the position information inside.

The communication center is a facility that manages, as a database, road surface condition information for each road location in the map data, and performs mapping of the road surface condition that changes momentarily based on the received determination result data. That is, the communication center updates the road surface condition information for each road location in the map data based on the received determination result data. Then, the communication center provides road surface data to the vehicle from the database. The communication center can also collect weather information and the like, correct each road surface data based on the weather information and the like, and can update it as more reliable road surface data. A more accurate road surface condition can be obtained by transmitting the road surface condition determination result data to such a communication center, and the road surface condition not only on the current road surface but also on the road surface to be traveled precedes. You can get it.

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 (8)

1. A tire side device (1) disposed in a tire (3) provided in a vehicle and transmitting road surface data that is data relating to a road surface condition; and a vehicle side disposed in the vehicle and receiving the road surface data A road surface condition judging device having a vehicle body side system (2) for judging a condition,
   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
   A second transmission / reception unit (25) performing data communication with the tire-side device, determination of a road surface state based on the road surface data received by the second transmission / reception unit, and activation to make the vehicle ready to start The on / off state of the switch (30) is determined, and when the activation switch is switched from off to on, the communication connection between the first transmission / reception unit and the second transmission / reception unit is established, and the activation switch A second control unit (26) for transmitting a disconnection request signal for instructing the tire device to disconnect the connection from the second transmission / reception unit when switched from on to off; apparatus.
2. The first control unit determines whether the vehicle is traveling or stopping based on the detection signal, and when the vehicle is stopped for a predetermined time, the first transmission / reception unit and the first control unit The road surface condition determination apparatus according to claim 1, which disconnects communication connection with the second transmission / reception unit.
3. When the activation switch is turned on, the second control unit is configured to set the first transmission / reception unit and the second transmission / reception unit even after the connection of communication between the first transmission / reception unit and the second transmission / reception unit is established. (2) It is determined whether or not the communication between the two transmission / reception units is in connection, and if the connection is not in progress, a connection of communication between the first transmission / reception unit and the second transmission / reception unit is established. The road surface state determination apparatus of claim 2.
4. A plurality of the tires are provided, and the tire side device is disposed on each of the plurality of tires.
   The tire-side devices disposed in each of the plurality of tires are communicable with each other, and when receiving the disconnection request signal from the second control unit, the tire-side devices are directed to the other tire-side devices. The road surface condition determining apparatus according to any one of claims 1 to 3, which transmits a disconnection request signal instructing a disconnection instruction.
5. The first control unit transmits an advertisement signal through the first transmission / reception unit when the vehicle starts traveling.
   When the second control unit receives the advertisement signal through the second transmission / reception unit, a connection for establishing the connection to the tire-side device disposed in each of the plurality of tires from the second transmission / reception unit The road surface condition determination apparatus according to any one of claims 1 to 4, which transmits a request signal.
6. The tire-side device has a start control unit (14) that controls switching between the start state and the sleep state in the first control unit and the first transmission / reception unit,
   The road surface state according to any one of claims 1 to 5, wherein the activation control unit switches the first control unit and the first transmission / reception unit from the activation state to the sleep state when the connection is disconnected. Discrimination device.
7. The start control unit receives the detection signal of the vibration detection unit, and detects the traveling of the vehicle based on the detection signal, and starts the first control unit and the first transmission / reception unit from the sleep state. The road surface state determination device according to claim 6, wherein the road surface state is switched to the state.
8. The second control unit continues operation by continuing power supply even after the start switch is switched from on to off, transmits the disconnection request signal, and transmits the disconnection request signal. The road surface condition judging device according to any one of claims 1 to 7, wherein the supply is stopped.

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