WO2019093437A1 - Dispositif d'estimation d'état de surface de route - Google Patents

Dispositif d'estimation d'état de surface de route Download PDF

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Publication number
WO2019093437A1
WO2019093437A1 PCT/JP2018/041545 JP2018041545W WO2019093437A1 WO 2019093437 A1 WO2019093437 A1 WO 2019093437A1 JP 2018041545 W JP2018041545 W JP 2018041545W WO 2019093437 A1 WO2019093437 A1 WO 2019093437A1
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WIPO (PCT)
Prior art keywords
tire
road surface
control unit
transmission
unit
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PCT/JP2018/041545
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English (en)
Japanese (ja)
Inventor
雅士 森
渡部　宣哉
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株式会社デンソー
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Publication date
Priority claimed from JP2018118775A external-priority patent/JP2019089532A/ja
Application filed by 株式会社デンソー filed Critical 株式会社デンソー
Publication of WO2019093437A1 publication Critical patent/WO2019093437A1/fr
Priority to US16/841,488 priority Critical patent/US11091163B2/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C19/00—Tyre parts or constructions not otherwise provided for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/02—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to ambient conditions
    • B60W40/06—Road conditions
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01W—METEOROLOGY
    • G01W1/00—Meteorology
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
    • G—PHYSICS
    • G08—SIGNALLING
    • G08C—TRANSMISSION SYSTEMS FOR MEASURED VALUES, CONTROL OR SIMILAR SIGNALS
    • G08C17/00—Arrangements for transmitting signals characterised by the use of a wireless electrical link
    • G08C17/02—Arrangements for transmitting signals characterised by the use of a wireless electrical link using a radio link

Definitions

  • 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.
  • 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.
  • 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.
  • 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.
  • 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 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
  • 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.
  • 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.
  • FIG. 1 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
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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 ⁇ is low is achieved.
  • 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.
  • 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.
  • the acceleration acquisition unit 10 is configured of an acceleration sensor.
  • 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.
  • 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.
  • 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.
  • 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).
  • 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.
  • 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”.
  • 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
  • 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.
  • the communication control unit 11 d disconnects the communication connection with the receiver 21 based on the received disconnection request signal.
  • 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.
  • ID information unique identification information
  • 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.
  • the power supply unit 13 can also be configured by a power generation device, a storage battery, and the like.
  • the activation control unit 14 controls activation and sleep of the functions of the units of the tire-side device 1.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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
  • 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.
  • 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.
  • 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.
  • the communication control unit 26 b 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.
  • 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.
  • the driver can keep in mind the driving corresponding to the road surface condition, and the danger of the vehicle can be avoided.
  • 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.
  • 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.
  • the notification device 23 is configured of, for example, a meter indicator, and is used when notifying the driver of the road surface condition.
  • 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.
  • the meter display was mentioned as the example as the alerting
  • the tire device 100 is configured as described above.
  • 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.
  • in-vehicle LAN abbreviation of Local Area Network
  • CAN abbreviation of Controller Area Network
  • 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.
  • 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.
  • 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.
  • the acceleration acquisition unit 10 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.
  • 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.
  • the output voltage of the acceleration acquiring unit 10 takes a second peak value.
  • 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.
  • step-in area 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
  • step-out area an instant at which it is separated from the road surface
  • step-in area includes the timing at which the first peak value is obtained
  • step-out area includes the timing at which the second peak value is obtained.
  • 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”.
  • 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.
  • 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.
  • 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.
  • 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.
  • the number of sections for one tire rotation is n (where n is a natural number).
  • 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
  • This feature quantity is called a feature vector
  • 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.
  • 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.
  • the determinant of the current feature is X (r)
  • the determinant of the previous feature is X (r ⁇ 1)
  • 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 .
  • 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.
  • 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.
  • 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.
  • 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.
  • n 5 and i is represented by 1 ⁇ i ⁇ 5.
  • the feature vector Xi of each section during the current rotation is Xi (r)
  • the feature vector of each section before one rotation is Xi (r-1).
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • various kernel functions can be used to determine the degree of similarity.
  • 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.
  • the tire side process shown in FIG. 8 is performed.
  • each process of FIG. 7 and FIG. 8 is demonstrated in order according to a time series.
  • 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.
  • 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.
  • 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.
  • 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.
  • step S200 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • step S ⁇ b> 110 the control unit 26 determines whether or not the advertisement signal from each tire-side device 1 has been received.
  • 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.
  • the control unit 26 makes an affirmative determination in step S110.
  • an advertisement signal from at least one tire side device 1 is received, an affirmative determination is made in step S110. You may
  • 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.
  • 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.
  • 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.
  • 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.
  • data in the vicinity of the “step-in area” or in the vicinity of the “kicking-out area” is sufficient.
  • 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.
  • step S245 the extraction of the feature amount performed in step S245 is performed by the method as described above.
  • step S250 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.
  • 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.
  • 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.
  • connection 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.
  • each tire side device 1 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • the vibration sensor unit 1a constituting the vibration detection unit is constituted by an acceleration sensor
  • other elements capable of detecting vibration for example, piezoelectric elements etc.
  • 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. this is also merely an example, and other data may be used as road surface data.
  • 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.
  • the road surface data is transmitted when there is a change in the road surface state.
  • the road surface data may be transmitted at another timing.
  • the road surface data may be transmitted every time the tire 3 makes one rotation or a predetermined rotation, or at predetermined time intervals.
  • 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).
  • 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.
  • the change of the road surface state may be determined by other various methods.
  • the road surface data including the feature amount this time is transmitted from the tire device 1.
  • the previous feature amount may be included in the road surface data.
  • 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.
  • 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.
  • 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.
  • the tire device 1 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.
  • this is also just an example, and various methods for establishing communication connection can be applied.
  • 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.
  • a connection request signal may be transmitted from the tire side devices 1 to the receiver 21 side to establish a connection.
  • 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.
  • 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.
  • 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.

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Abstract

Selon l'invention, quand un état de surface de route doit être estimé, la mise en service d'un commutateur de démarrage (30) provoque l'établissement d'une connexion entre un dispositif côté pneu (1) et un système côté caisse de véhicule (2), et une communication de données est effectuée. Ensuite, quand le commutateur de démarrage (30) est mis hors service, un signal de demande de déconnexion est transmis à partir du système côté caisse de véhicule (2) jusqu'au dispositif côté pneu (1). En résultat, le dispositif côté pneu (1) peut également reconnaître que le commutateur de démarrage (30) a été mis hors service. Le dispositif côté pneu (1) peut par conséquent être empêché de tenter de maintenir la connexion même après que le commutateur de démarrage (30) a été mis hors service, de façon à rendre ainsi possible de déconnecter la connexion au niveau du dispositif côté pneu (1), de façon à réduire la consommation d'énergie.
PCT/JP2018/041545 2017-11-10 2018-11-08 Dispositif d'estimation d'état de surface de route WO2019093437A1 (fr)

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US16/841,488 US11091163B2 (en) 2017-11-10 2020-04-06 Road surface condition assessing device

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JP2017217113 2017-11-10
JP2017-217113 2017-11-10
JP2018118775A JP2019089532A (ja) 2017-11-10 2018-06-22 路面状態判別装置
JP2018-118775 2018-06-22

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11376901B2 (en) * 2018-03-02 2022-07-05 Denso Corporation Road surface condition determination device performing sensing based on different sensing conditions

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JP2008162534A (ja) * 2006-12-29 2008-07-17 Denso Corp 車輪位置検出装置、車輪位置検出用の送受信機、受信機および車輪位置検出装置を備えたタイヤ空気圧検出装置
JP2010234858A (ja) * 2009-03-30 2010-10-21 Denso Corp タイヤ空気圧監視装置
JP2016107833A (ja) * 2014-12-05 2016-06-20 株式会社ブリヂストン 路面状態判別方法
JP2017520451A (ja) * 2014-06-19 2017-07-27 サルティカ アライド ソリューションズ スンディリアンブルハド 無線タイヤ監視システム

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Publication number Priority date Publication date Assignee Title
JP2008162534A (ja) * 2006-12-29 2008-07-17 Denso Corp 車輪位置検出装置、車輪位置検出用の送受信機、受信機および車輪位置検出装置を備えたタイヤ空気圧検出装置
JP2010234858A (ja) * 2009-03-30 2010-10-21 Denso Corp タイヤ空気圧監視装置
JP2017520451A (ja) * 2014-06-19 2017-07-27 サルティカ アライド ソリューションズ スンディリアンブルハド 無線タイヤ監視システム
JP2016107833A (ja) * 2014-12-05 2016-06-20 株式会社ブリヂストン 路面状態判別方法

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11376901B2 (en) * 2018-03-02 2022-07-05 Denso Corporation Road surface condition determination device performing sensing based on different sensing conditions

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