WO2019088023A1 - 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
WO2019088023A1
WO2019088023A1 PCT/JP2018/040124 JP2018040124W WO2019088023A1 WO 2019088023 A1 WO2019088023 A1 WO 2019088023A1 JP 2018040124 W JP2018040124 W JP 2018040124W WO 2019088023 A1 WO2019088023 A1 WO 2019088023A1
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WIPO (PCT)
Prior art keywords
road surface
tire
surface state
unit
data
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PCT/JP2018/040124
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English (en)
Japanese (ja)
Inventor
高俊 関澤
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株式会社デンソー
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Priority claimed from JP2018108583A external-priority patent/JP6828716B2/ja
Application filed by 株式会社デンソー filed Critical 株式会社デンソー
Publication of WO2019088023A1 publication Critical patent/WO2019088023A1/fr
Priority to US16/859,524 priority Critical patent/US11498571B2/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
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M17/00—Testing of vehicles
    • G01M17/007—Wheeled or endless-tracked vehicles
    • G01M17/02—Tyres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/17—Using electrical or electronic regulation means to control braking
    • B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters

Definitions

  • the present disclosure detects a vibration received by a tire and generates a road surface data indicating a road surface state based on the vibration data, and a vehicle body side system that receives the road surface data and estimates the road surface state.
  • the present invention relates to a state estimation device.
  • Patent Document 1 there is provided a road surface state estimation method including an acceleration sensor on the back of the tire tread, detecting the vibration applied to the tire by the acceleration sensor, and estimating the road surface state based on the detection result of the vibration. Proposed.
  • the feature vector is extracted from the tire's vibration waveform detected by the acceleration sensor, and the similarity between the extracted feature vector and all the support vectors stored for each type of road surface is calculated.
  • the kernel function is used to calculate the degree of similarity between the extracted feature vector and all the support vectors, and the kind of road surface having the highest degree of similarity, eg, dry road surface, wet road surface, etc. Presumed.
  • the control unit provided in the tire calculates the degree of similarity and estimates the road surface condition, and transmits the estimation result to the vehicle body system
  • the support unit is stored in the control unit provided in the tire. It is necessary to perform data processing of similarity calculation. For this reason, the amount of power consumption is enormous in the tire, and the amount of memory consumption in the control unit is also enormous because enormous data storage and data processing are required.
  • control unit provided in the tire only extracts the feature vector, transmits the data to the vehicle body side system, and calculates the similarity to all the support vectors in the vehicle body side system to determine the road surface state. It can also be done. In that case, since the timing of data transmission can not be determined, the frequency of communication can not but be increased, and power consumption is increased by high frequency data transmission.
  • the road surface state estimation device includes a tire side device disposed in a tire and a vehicle body side system disposed in the vehicle body side.
  • the tire side device performs data communication between a vibration detection unit that outputs a detection signal according to the magnitude of the vibration of the tire, a first control unit that creates road surface data based on the detection signal, and a vehicle body side system. And a first transmission / reception unit to perform.
  • the vehicle body side system is based on the information on the road surface condition acquired by the peripheral device that acquires information on the road surface condition, the second transmitting / receiving unit that performs data communication with the tire device, and the road surface condition
  • the second transmitting / receiving unit causes the tire transmitting / receiving unit to transmit vehicle body side information indicating that there is a change in the road surface condition, and the road surface based on the road surface data received by the second transmitting / receiving unit.
  • a second control unit configured to estimate a state.
  • the road surface state is estimated by such a road surface state estimation device
  • transmission of the road surface data from the tire side device is made to be only at the change timing of the road surface state.
  • the road surface data is transmitted from the tire side device only at the timing when it is determined that the road surface state has been changed by the tire side device or the vehicle body side system. Therefore, the communication frequency can be reduced, and power saving of the first control unit in the tire can be realized.
  • the support vector storage unit for storing the support vector in the first control unit of the tire-side device but also the structure not provided with the support vector can be realized.
  • the support vector storage unit is not provided, the memory saving of the first control unit in the tire can be achieved.
  • 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 the figure which showed the block configuration in the vehicle mounting state of the tire apparatus concerning 1st Embodiment. It is a block diagram showing details of a tire side device and a vehicle body side system. It is a cross-sectional schematic diagram of the tire in which the tire side apparatus was attached. It is an output voltage waveform figure of the acceleration acquisition part at the time of tire rotation. It is a figure which shows a mode that the detection signal of the acceleration acquisition part was divided for every time window of predetermined time width
  • the determinants Xi (r) and Xi (r-1) in each section obtained by dividing the time axis waveform at the time of the current rotation of the tire and the time axis waveform at the time before one rotation by the time window of the predetermined time width T Is a diagram showing the relationship between the distance yz and the distance yz . It is a flowchart of the vehicle body side determination processing which the control part of a vehicle body side system performs. It is a flowchart of the tire side determination process which the control part of a tire side apparatus performs. It is a flowchart of the data transmission process which the control part of a tire side apparatus performs.
  • a tire device 100 having a road surface state estimation function according to the present embodiment will be described with reference to FIGS. 1 to 10.
  • the tire device 100 according to the present embodiment estimates the road surface state during traveling based on the vibration applied to the ground contact surface of the tire provided on each wheel of the vehicle, and notifies of the danger of the vehicle or the vehicle based on the road surface state. It performs exercise control and the like.
  • the tire device 100 is configured to have a tire side device 1 provided on the wheel side and a vehicle body side system 2 including each part provided on the vehicle body side.
  • the vehicle body side system 2 includes a receiver 21, an electronic control unit for brake control (hereinafter referred to as a brake ECU) 22, an informing device 23, a peripheral device 24, and the like.
  • the part of the tire device 100 that realizes the road surface state estimation function corresponds to the road surface state estimation device.
  • the receiver 21 and the peripheral device 24 in the tire side device 1 and the vehicle body side system 2 constitute a road surface state estimation device.
  • the tire device 100 of the present embodiment transmits data (hereinafter referred to as road surface data) according to the road surface condition on the traveling road surface of the tire 3 from the tire device 1 and receives the road surface data by the receiver 21 Make an estimate of Specifically, the tire side device 1 transmits road surface data when it is determined that the road surface state has changed. Further, the vehicle body side system 2 also determines that there is a change in the road surface state based on the information from the peripheral device 24, and when there is a change in the road surface state, information to that effect (hereinafter referred to as the vehicle body side The information is transmitted to the tire side device 1).
  • road surface data data (hereinafter referred to as road surface data) according to the road surface condition on the traveling road surface of the tire 3 from the tire device 1 and receives the road surface data by the receiver 21 make an estimate of Specifically, the tire side device 1 transmits road surface data when it is determined that the road surface state has changed. Further, the vehicle body side system 2 also determines that there is a change in the road surface
  • the tire-side device 1 transmits road surface data also when the vehicle-side information is transmitted, in addition to the case where it is determined that the road surface state has changed by itself. Then, the receiver 21 receives road surface data sent when there is a change in the road surface condition, and estimates the road surface condition based on the received road surface data.
  • the tire device 100 transmits the estimation result of the road surface condition in the receiver 21 to the notification device 23, and causes the notification device 23 to notify the estimation result of the road surface condition.
  • This makes it possible to convey the road surface condition to the driver, for example, a dry road, a wet road, or a frozen road, and to warn the driver if the road surface is slippery.
  • 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. Specifically, as shown in FIG. 2, the tire side device 1 is configured to include the acceleration acquiring unit 10, the control unit 11 and the data communication unit 12, and as shown in FIG. 3, the tread of the tire 3 31 is provided on the back side.
  • the acceleration acquisition unit 10 constitutes a vibration detection unit for detecting a vibration applied to the tire 3.
  • 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 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 quantity extraction unit 11a, a feature quantity storage unit 11b, a change determination unit 11c, and a transmission control unit 11d as functional units that perform those processes.
  • the feature amount extraction unit 11a extracts the feature amount of the tire vibration by processing the detection signal using the detection signal output from the acceleration acquisition unit 10 as a detection signal representing the vibration data in the tire tangential direction.
  • 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 via the transmission control unit 11d. The details of the feature quantities referred to here will be described later.
  • the feature amount storage unit 11 b stores the feature amount extracted by the feature amount extraction unit 11 a one turn before the tire 3 (hereinafter referred to as the “previous feature amount”). Since the fact that the tire 3 has made one rotation can be confirmed by a method described later, every time the tire 3 makes one rotation, the feature amount for one rotation is stored.
  • the feature amount for one rotation of the tire 3 may be updated every time the tire 3 makes one rotation, or a plurality of rotations may be stocked, and the tire 3 makes one rotation every time the tire 3 makes one rotation. You may delete old data. However, from the viewpoint of saving memory of the control unit 11 in the tire 3, it is preferable to reduce the amount of data to be stored, and therefore, it is preferable to update data each time the tire 3 makes one rotation.
  • the change determination unit 11c is configured to extract the feature quantity extracted by the feature quantity extraction unit 11a during the current rotation of the tire 3 (hereinafter referred to as the present feature quantity) and the previous feature quantity of the tire 3 stored in the feature quantity storage unit 11b. It is determined whether or not there is a change in road surface condition based on. Further, as described later, the change determination unit 11c also determines the presence or absence of the change in the road surface state based on whether or not the vehicle body side information is received from the receiver 21 of the vehicle body side system 2. When the change determination unit 11c determines that there is a change in the road surface state, it transmits a control signal indicating that to the transmission control unit 11d.
  • the change determination unit 11 c distinguishes the determination of the presence or absence of the change in the road surface state based on the feature amount in the tire device 1 and the determination of the presence or absence of the change in the road surface state based on the vehicle body side information from the vehicle body side system 2. The decision is being made.
  • the former determination is referred to as “tire side determination” and the latter determination is referred to as “vehicle side determination”.
  • the transmission control unit 11 d controls data transmission from the data communication unit 12.
  • the transmission control unit 11d receives a control signal indicating that there is a change in the road surface condition from the change determination unit 11c, it transmits the road surface data including the current feature amount extracted by the feature amount extraction unit 11a at that time. Tell the communication unit 12.
  • the road surface data indicates data communication if the result of the determination on the road surface state is a change either in the tire side determination result or the vehicle body side determination result. It is transmitted to the part 12.
  • the data communication unit 12 constitutes a first transmission / reception unit, and performs data communication with a data communication unit 25 described later of the receiver 21 in the vehicle body side system 2.
  • 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.
  • BLE abbreviation of Bluetooth Low Energy
  • wireless LAN such as wifi (abbreviation of Local Area Network)
  • Sub-GHz communication Ultra-wide band communication
  • ZigBee ZigBee, etc.
  • 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 transmission control unit 11 d, so data transmission is not performed every time the tire 3 makes one rotation, and when there is a change in the road surface condition Data transmission is performed only in
  • the data communication unit 12 receives it and transmits it to the change determination unit 11c.
  • the change determination unit 11c can determine the presence or absence of the change in the road surface state based on the transmitted vehicle body side information.
  • the receiver 21 is configured to have a data communication unit 25 and a control unit 26.
  • the data communication unit 25 is a part that configures a second transmission / reception unit that performs data communication with the tire side device 1, and road surface data including the present feature amount transmitted from the data communication unit 12 of the tire side device 1 It plays a role of receiving and communicating to the control unit 26. Also, when the vehicle-body-side information indicating that there is a change in the road surface state is transmitted from the control unit 26 based on the information of the peripheral device 24, it also plays a role of transmitting it to the data communication unit 12 of each tire-side device 1.
  • the data communication unit 25 is described here as one configuration, the data communication unit 25 may be configured separately for the transmission unit and the reception unit.
  • the control unit 26 corresponds to a second control unit, is configured by a well-known microcomputer including a CPU, a ROM, a RAM, an I / O, and the like, and performs various processes in accordance with a program stored in the ROM or the like.
  • the control unit 26 includes a support vector storage unit 26a, a state estimation unit 26b, and a change determination unit 26c as functional units that perform various processes.
  • the support vector storage unit 26a stores and stores support vectors for each type of road surface.
  • the support vector is a feature that serves as an example, and is obtained, for example, by learning using a support vector machine.
  • the vehicle equipped with the tire-side device 1 is run experimentally for each type of road surface, and at that time the feature quantity extracted by the feature quantity extraction unit 11a is learned for a predetermined number of tire rotations, and a typical feature quantity among them What is extracted a predetermined number of times is taken as a support vector. For example, feature amounts for one million rotations are learned for each type of road surface, and typical feature amounts for 100 rotations are extracted therefrom as support vectors.
  • the state estimation unit 26 b compares the current feature amount sent from the tire-side device 1 received by the data communication unit 25 with the support vector for each type of road surface stored in the support vector storage unit 26 a, Estimate the road surface condition. For example, the feature amount is compared with the support vector for each type of road surface, and the road surface of the support vector having the closest feature amount this time is estimated to be the current traveling road surface.
  • the change determination unit 26c determines that there is a change in the road surface condition based on the information from the peripheral device 24, and when there is a change in the road surface condition, the data communication unit 25 indicates the vehicle side information to that effect. To the data communication unit 12 of each tire-side device 1. In addition, since various things can be used for the peripheral device 24 as will be described later, the processing performed by the change determination unit 26 c differs depending on which device is applied as the peripheral device 24. Will be described later.
  • the control unit 26 transmits the estimated road surface state to the notification device 23, and notifies the driver of the road surface condition from the notification device 23 as necessary.
  • 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 state estimated through the notification device 23 may be displayed at all times, or the road surface state is determined only when the driving needs to be performed more carefully, such as a wet road or a frozen road. The status may be displayed to warn the driver.
  • 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 peripheral device 24 is configured by various devices provided in the vehicle, and plays a role of acquiring information on the road surface state and transmitting it to the change determination unit 26c.
  • the various devices provided in the vehicle may be any device as long as it can acquire information on the road surface state.
  • an on-vehicle camera, a wiper device, a brake ECU 22 or the like may be applied.
  • an on-vehicle camera When an on-vehicle camera is applied as the peripheral device 24, image data of a road surface in front of the vehicle is acquired by the on-vehicle camera, and the image data is transmitted to the change determination unit 26c.
  • the change determination unit 26c analyzes the image data of the on-vehicle camera, and determines that there is a change in the road surface state based on the analysis result.
  • drive information of the wiper device is transmitted to the change determination unit 26c.
  • the wiper device When the wiper device is driven, it is when it is raining or snowing.
  • the change determination unit 26c acquires, from the control unit of the wiper apparatus, information indicating that the wiper drive has been performed, and determines that there is a change in the road surface state based on the information.
  • the brake ECU 22 when the brake ECU 22 is applied as the peripheral device 24, information related to the road surface state used for various controls performed by the brake ECU 22 is transmitted to the change determination unit 26c.
  • the brake ECU 22 performs various controls such as ABS (abbreviation of Antilock Brake System) and VSC (abbreviation of Vehicle stability control), and estimates a road surface friction coefficient and a road surface state. Therefore, when the brake ECU 22 transmits information on the road surface condition, the change determination unit 26c determines that the road surface condition has changed based on the information.
  • a known method may be applied to the estimation of the road surface state based on the analysis of the image data acquired by the on-vehicle camera and the estimation of the road surface state by the brake ECU 22.
  • the tire device 100 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 T Divide into each section with the time window of.
  • T a predetermined time width
  • 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, and the features of the sections
  • the distance between the coordinates indicated by the vector Xi is the distance between the coordinates in the six-dimensional space.
  • 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 change determination unit 26c performs the vehicle body side determination process shown in FIG. 7 based on the information on the road surface state acquired from the peripheral device 24. This process is performed, for example, during a predetermined control cycle while the ignition (not shown) is on, preferably while the vehicle is traveling.
  • the change determination unit 26 c executes a process of acquiring information on the road surface state from the peripheral device 24 in step S ⁇ b> 100.
  • a process of acquiring information on the road surface state from the peripheral device 24 in step S ⁇ b> 100 For example, when an on-vehicle camera is applied as the peripheral device 24, acquisition of image data, information indicating that the wiper device is driven when the wiper device is applied, road surface when the brake ECU 22 is applied Information on the coefficient of friction or road surface condition is acquired.
  • step S110 the process proceeds to step S110, and as the vehicle body side determination, it is determined whether or not there is a change in the road surface state based on the information acquired in step S100. Thereafter, when the determination in step S110 is affirmative, the process proceeds to step S120, and the data communication unit 25 transmits vehicle body side information indicating that there is a change in the road surface state to each tire side device 1. And when a negative determination is carried out by step S110, a vehicle body side determination process is complete
  • the control unit 11 executes the tire side determination process shown in FIG. 8 and the data transmission process shown in FIG. This process is performed every predetermined control cycle.
  • the control unit 11 performs an input process of a detection signal of the acceleration acquisition unit 10 in step S200. This process is continued in the subsequent step S210 for a period until the tire 3 makes one revolution. Then, when the detection signal of the acceleration acquisition unit 10 is input for one rotation of the tire, the process proceeds to the subsequent step S220, and the feature value of the time axis waveform of the detection signal of the acceleration acquisition unit 10 for one rotation of the tire input as the current feature value. Extract The processes of steps S200 to S220 described above are performed by the feature amount extraction unit 11a of the control unit 11.
  • the fact that the tire 3 has made one rotation is determined based on the time axis waveform of the detection signal of the acceleration acquisition unit 10. That is, since the detection signal draws the time axis waveform shown in FIG. 4, one rotation of the tire 3 can be grasped by confirming the first peak value and the second peak value of the detection signal.
  • the vibration level in the detection signal of the acceleration acquiring unit 10 is smaller than the threshold, it is detected as a period less susceptible to the road surface condition among the "pre-step-in region" and the "after kicking region".
  • the signal may not be input.
  • the extraction of the feature amount performed in step S220 is performed by the method as described above.
  • step S230 the similarity is determined by the above-described method based on the current feature amount and the previous feature amount. For example, the similarity is compared with the threshold Th to determine whether there is a change in the road surface state. Determine if This process is executed based on the current feature amount extracted by the feature amount extraction unit 11a and the previous feature amount stored in the feature amount storage unit 11b in step S250 described later.
  • step S230 When an affirmative determination is made in step S230, the fact that there is a change in the road surface condition is stored in step S240.
  • the process of steps S230 and S240 is performed by the change determination unit 11c of the control unit 11.
  • step S250 the current feature amount is stored as the previous feature amount in the feature amount storage unit 11b, and the process is ended.
  • step S300 it is determined whether or not the tire side device 1 determines that there is a change in the road surface state. This determination is performed based on whether or not the change in the road surface state is stored in step S240 of FIG. 8 described above. If an affirmative determination is made here, the process proceeds to step S310, and if a negative determination is made, the process proceeds to step S320. Then, in step S310 or step S320, it is determined whether or not it is determined in the vehicle body side system 2 that there is a change in the road surface state. This determination is performed based on whether or not the vehicle body side information transmitted in step S120 of FIG. 7 described above is received.
  • step S310 the process proceeds to step S330, and data of “high reliability” is added to road surface data including data of the feature amount this time, and the data communication unit 12 is notified. If the determination is affirmative in step S320, the process proceeds to step S340, and data of “in reliability” is added to the road surface data including the data of the feature amount this time, and the data communication unit 12 is notified. Furthermore, when the negative determination is made in step S310, the process proceeds to step S350, and data of “reliability is low” is added to the road surface data including the data of the feature amount this time and transmitted to the data communication unit 12.
  • step S310 The case where an affirmative determination is made in step S310 is a case where it is determined that there is a change in the road surface condition in both the tire side device 1 and the vehicle body side system 2. Therefore, in this case, it can be said that the reliability of the determination that there is a change in the road surface condition is high. Therefore, the road surface data sent to the data communication unit 12 includes data “high reliability”.
  • the determination in step S320 is affirmed is the case where it is determined that the road surface state has been changed in the vehicle body side system 2 although the tire side device 1 has not been determined to have changed the road surface state.
  • the reliability of the determination that there is a change in the road surface condition is relatively high, although this is not the same as the case where the positive determination is made in step S310. Therefore, the road surface data sent to the data communication unit 12 includes the data “in reliability”.
  • step S310 the case where the negative determination is made in step S310 is a case where it is determined that the road surface state has changed in the tire device 1, but the road surface state has not been determined in the vehicle body side system 2.
  • the road surface data sent to the data communication unit 12 includes data of “reliability is low”.
  • the data communication unit 12 when road surface data is transmitted from the transmission control unit 11 d to the data communication unit 12, the data communication unit 12 outputs the data to the receiver 21. Thereby, the road surface data from each tire side device 1 is received by the receiver 21. As described above, road surface data including the feature amount is transmitted from the data communication unit 12 only when there is a change in the road surface state, and data transmission is not performed when there is no change in the road surface state. I have to. Therefore, the communication frequency can be reduced, and power saving of the control unit 11 in the tire 3 can be realized.
  • control unit 26 performs the road surface state estimation process shown in FIG. This process is performed every predetermined control cycle.
  • step S400 data reception processing is performed. This process is performed by the control unit 26 taking in the road surface data when the data communication unit 25 receives the road surface data. When the data communication unit 25 is not receiving data, the control unit 26 ends the process without taking in road surface data.
  • step S410 it is determined whether data has been received. If it has been received, the process proceeds to step S420. If it has not been received, the processes of steps S400 and S410 are repeated until it is received.
  • step S420 the road surface state is estimated.
  • the road surface state is estimated by comparing the current feature amount included in the received road surface data with the support vector classified by road surface type stored in the support vector storage unit 26a.
  • the feature amount is obtained as the similarity with all the support vectors for each type of road surface, and the road surface of the support vector having the highest similarity is estimated to be the current traveling road surface.
  • the calculation of the degree of similarity at this time may use the same method as the calculation of the degree of similarity between the current feature amount and the previous feature amount performed in step S230 of FIG.
  • the method of estimating the road surface state can be changed according to the reliability.
  • each element of the matrix indicating the feature amount used for estimating the road surface condition also includes an element that becomes prominent on a dry road, an element that becomes prominent on a wet road surface, and an element that becomes prominent on a frozen road.
  • the elements of all the matrices indicating the feature amounts included in the road surface data are not used to calculate the similarity, and among the elements, elements that become particularly prominent for each road surface Let's take out only and calculate the similarity.
  • the number of elements is increased and the calculation of the similarity is performed as compared to the case of “in high reliability”. Then, in the case of “reliability is low”, calculation of similarity is performed using all elements of the determinant.
  • the calculation of the degree of similarity can be performed by narrowing down the elements. For this reason, for example, as in the case of “high reliability”, it is also possible to estimate the road surface condition more accurately by taking out only the element that is particularly remarkable for each road surface.
  • the road surface state after the change is either a wet road or a frozen road when the road surface state changes. It may not be clear which way it is. In this case, if the elements that become prominent in the wet path and the elements that become prominent in the freezing path are extracted and the similarity degree is calculated using only these elements, it will be a wet path more clearly It can be estimated if it is a freezing path.
  • the road surface condition is estimated by the tire device 100 according to the present embodiment.
  • transmission of road surface data including the present feature amount from the tire device 1 is performed only at the change timing of the road surface state.
  • the road surface data from the tire side device 1 is transmitted only at the timing when the tire side device 1 or the vehicle body side system 2 determines that there is a change in the road surface state. Therefore, the communication frequency can be reduced, and power saving of the control unit 11 in the tire 3 can be realized.
  • the tire device 100 does not have to include the support vector storage unit for storing the support vector in the control unit 11 of the tire side device 1, memory saving of the control unit 11 in the tire 3 can be achieved. .
  • the data processing of similarity calculation by the control unit 11 of the tire-side device 1 may be performed only on the current feature amount and the previous feature amount, and on the similarity calculation of the current feature amount and all support vectors. It may be performed by the vehicle body side system 2. For this reason, it is possible to further suppress the consumption of the memory in the control unit 11 in the tire 3, and to realize memory saving.
  • tire device 100 which can realize memory saving and power saving of control part 11 in tire 3, and tire device 100 containing it.
  • the road surface data from the tire side device 1 It is supposed to be sent. Therefore, even when the tire side device 1 can not grasp the change of the road surface state, the road surface data can be transmitted to the vehicle body side system 2, and the change of the road surface state can be recognized more accurately.
  • the road surface condition estimation method it is possible to change the road surface condition estimation method according to the reliability. For example, it is also possible to estimate the road surface condition with a smaller amount of data according to the reliability. Therefore, the amount of data to be sent as road surface data can be changed from each tire-side device 1 according to the level of reliability, and the power necessary for data transmission can be further reduced, thereby further saving the cost. Power can be realized.
  • the present embodiment is different from the first embodiment in that it is possible to estimate the road surface condition in each tire side device 1 with respect to the first embodiment, and the other is the same as the first embodiment. Only the part will be described.
  • a support vector storage unit 11e is provided instead of the feature storage unit 11b provided in the first embodiment, and the support vector storage unit 26a of the receiver 21 is eliminated.
  • the tire side device 1 can be calculated by the change determination unit 11c calculating the degree of similarity between the current feature value extracted by the feature value extraction unit 11a and all the support vectors stored in the support vector storage unit 11e. In the above, it is possible to determine the change of the road surface condition. Then, when there is a change in the road surface state, data indicating the estimation result of the road surface state based on the calculation of the similarity is transmitted from the tire device 1 as road surface data.
  • the road surface data transmitted by the tire side device 1 is received, and the road surface state indicated by the road surface data is transmitted from the state estimation unit 26b to the brake ECU 22 and the notification device 23.
  • the tire side device 1 can be provided with the support vector storage unit 11 e so that the tire side device 1 can estimate the road surface state. Even in this case, it can be determined based on the estimation result whether or not there is a change in the road surface state. For this reason, when there is a change in the road surface condition in the tire side device 1 or when the vehicle body side information is transmitted from the vehicle body side system 2, the road surface data including the estimation result or the feature value of the road surface condition is transmitted. You can do so. Thereby, although the effect of the memory saving of the control unit 11 in the tire 3 can not be obtained, the same effect as that of the first embodiment can be obtained such that power saving can be realized.
  • the tire side device 1 does not determine the change in the road surface state based on the feature amount with respect to the first embodiment, but determines the change in the road surface state based on the vehicle body side information transmitted from the vehicle body side system 2 Can only be done.
  • the other parts of this embodiment are the same as those of the first embodiment, so only the parts different from the first embodiment will be described.
  • the feature storage unit 11b provided in the first embodiment is eliminated. Further, the change determination unit 11 c can determine that there is a change in the road surface state based on the vehicle body side information sent from the vehicle body side system 2. Then, when there is a change in the road surface state, road surface data including the feature amount is transmitted from the tire side device 1.
  • the receiver 21 determines that there is a change in the road surface state based on the information from the peripheral device 24, the receiver 21 transmits the vehicle body side information to the tire side device 1. Also, the receiver 21 receives the road surface data transmitted by the tire-side device 1, and from the state estimation unit 26b, the feature amount included in the road surface data and the support vector by road surface type stored in the support vector storage portion 26a. The road surface condition is estimated by comparing with. Then, the estimation result of the road surface state is transmitted from the state estimation unit 26 b to the brake ECU 22 and the notification device 23.
  • the tire side device 1 executes the tire side determination process shown in FIG. First, in steps S500 to S520, the same processes as steps S200 to S220 of the tire side determination process shown in FIG. 8 are executed. Then, in step S530, it is determined whether or not it is determined in the vehicle body side system 2 that there is a change in the road surface state. Here, it is positively determined that the vehicle body side information indicating that it is determined that there is a change in the road surface condition described above is transmitted from the vehicle body side system 2, and it is negatively determined that the vehicle body side information is not transmitted. If an affirmative determination is made here, the process proceeds to step S540, the road surface data of the present feature amount obtained in step S520 is transmitted to end the process, and when a negative determination is made, the process ends.
  • the road surface state estimation process shown in FIG. 10 is performed in the tire side device 1 so that the road surface state estimation based on the road surface data transmitted from the tire side device 1 is performed.
  • the vehicle body side information is transmitted to the tire side device 1, and the road surface data is transmitted from the tire side device 1 only in that case. You may do so.
  • the tire side device 1 can not determine that there is a change in the road surface state, it does not have to perform the determination, so that the memory saving of the control unit 11 in the tire 3 is further reduced. realizable. Further, since the road surface data can be requested to the tire side device 1 only when the vehicle body side system 2 requires the road surface data, data transmission of the tire side device 1 can be further restricted. Therefore, power saving of the control unit 11 of the tire side device 1 can be realized.
  • the feature amount one rotation before is stored as the feature amount at the time of the past rotation of the tire 3.
  • the feature amount storage unit 11b does not necessarily have to be the feature amount one rotation before. That is, the feature amount storage unit 11b stores the feature amounts before multiple rotations as the past feature amounts without being limited to storing the feature amounts of the previous time as the feature amounts of the tire 3 in the past rotation (hereinafter referred to as past feature amounts).
  • the average value of the past feature amounts for a plurality of rotations may be stored.
  • the previous feature value among the past feature values may be used, or an average value of a plurality of past values including the previous feature value may be used.
  • the vibration detection unit can also be configured by an element that can perform other vibration detection, such as a piezoelectric element.
  • 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 condition before the change can also be estimated by comparing the previous feature quantity with the support vector. Therefore, it is possible to estimate both of the road surface condition before and after the change and to more accurately recognize the change of the road surface condition.
  • control unit 26 of the receiver 21 provided in the vehicle body side system 2 obtains the similarity between the current feature amount and the support vector to estimate the road surface state.
  • the similarity may be determined or the road surface state may be estimated by another ECU, for example, the control unit of the brake ECU 22.
  • 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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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Mathematical Physics (AREA)
  • Transportation (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)
  • Tires In General (AREA)

Abstract

Selon l'invention, une première unité de commande (11) d'un dispositif côté pneu (1) détermine qu'un état de surface de route a changé. Une seconde unité de commande (26) d'un système côté carrosserie de véhicule (2) estime qu'il y a eu un changement de l'état de surface de route sur la base d'informations d'un dispositif périphérique (24) et transmet des informations côté carrosserie de véhicule au dispositif côté pneu (1) lorsqu'il y a un changement dans l'état de surface de route. Dans le dispositif côté pneu (1), des données de surface de route comprenant une quantité caractéristique actuelle sont transmises à partir du dispositif côté pneu (1) à une moment où l'état de surface de route a changé.
PCT/JP2018/040124 2017-10-30 2018-10-29 Dispositif d'estimation d'état de surface de route WO2019088023A1 (fr)

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JP2017209401 2017-10-30
JP2017-209401 2017-10-30
JP2018-108583 2018-06-06
JP2018108583A JP6828716B2 (ja) 2017-10-30 2018-06-06 路面状態推定装置

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11198336B2 (en) 2017-10-30 2021-12-14 Denso Corporation Transmission and receiving arrangement for a tire pressure detection device

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005170222A (ja) * 2003-12-10 2005-06-30 Toyota Motor Corp 車輪情報処理装置
JP2007055284A (ja) * 2005-08-22 2007-03-08 Bridgestone Corp 路面状態推定方法、路面状態推定用タイヤ、路面状態推定装置、及び、車両制御装置
JP2009056818A (ja) * 2007-08-29 2009-03-19 Yokohama Rubber Co Ltd:The 車両走行路面状態推定システム

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2005170222A (ja) * 2003-12-10 2005-06-30 Toyota Motor Corp 車輪情報処理装置
JP2007055284A (ja) * 2005-08-22 2007-03-08 Bridgestone Corp 路面状態推定方法、路面状態推定用タイヤ、路面状態推定装置、及び、車両制御装置
JP2009056818A (ja) * 2007-08-29 2009-03-19 Yokohama Rubber Co Ltd:The 車両走行路面状態推定システム

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11198336B2 (en) 2017-10-30 2021-12-14 Denso Corporation Transmission and receiving arrangement for a tire pressure detection device

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