Vehicle risk avoidance device

Abstract

Vehicle risk avoidance device (100) for implementing a regulation to avoid a risk to a vehicle, wherein the vehicle risk avoidance device (100) comprises: a tire sensor (1) attached to a rear surface of a tire (3) of the vehicle and comprising a vibration detection unit (11) for outputting a detection signal corresponding to the magnitude of a vibration of the tire (3), a signal processing unit (13) for detecting a road surface condition corresponding to vibration data represented by the detection signal of the vibration detection unit (11), and a transmission unit (14) for transmitting road surface data indicating the road surface condition; and a vehicle body-side system (2) arranged on a vehicle body and comprising a receiver (21) for receiving the road surface data transmitted by the transmission unit (14), a vehicle communication device (24) for transmitting the road surface data to a communication center (200) that collects road information and obtains the road surface data indicating the road surface condition of a road on which the vehicle is to travel, from the communication center (200), a road information acquisition unit (22) for obtaining road information, a position information acquisition unit (22) for obtaining an instantaneous position of the vehicle, and a vehicle speed acquisition unit (23) for obtaining a vehicle speed as a speed of the vehicle, wherein: The vehicle body-side system (2) further comprises a control unit (21) which determines the risk to the vehicle on the basis of the road information obtained by the road information determination unit (22), the instantaneous position obtained by the position information determination unit (22), the vehicle speed obtained by the vehicle speed determination unit (23) and the road surface data obtained by the communication center (200) and performs a control to avoid the risk to the vehicle when the control unit (21) determines that there is a risk to the vehicle; when the road surface data is determined by the communication center (200), the control unit (21) determines the risk to the vehicle based on the road surface data obtained from the communication center (200); and if the road surface data is not determined by the communication center (200), the control unit (21) determines the risk to the vehicle based on the road surface data obtained from the tire sensor (1); characterized by the fact that: the control unit (21) determines the risk to the vehicle according to a map or relationship expression which specifies a relationship between the risk to the vehicle, a vehicle speed, a curve information from the road information and a road surface friction coefficient from the road surface data; the signal processing unit (13) comprises: a ground contact section identification unit (13a) that identifies a ground contact section during a rotation of the tire (3) where a part of the tire (3), corresponding to an arrangement position of the vibration detection unit (11), contacts a ground; and a high-frequency level calculation unit (13b) for calculating a level of a high-frequency component of the detection signal in the ground contact section; and the transmission unit (14) transmits a calculation result of the level of the high-frequency component as the road surface data indicating the road surface condition.

Description

[0001] This application is based on Japanese Patent Application No. 2016-30254, filed on February 19, 2016, the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a vehicle risk avoidance device that detects a road surface condition during a vehicle's travel and performs control for avoiding a risk during the travel based on the road surface condition, for example, control for notifying a driver of the risk or generating a braking force acting on the vehicle.

[0003] A road surface information distribution system that measures the smoothness of a road on which a vehicle is traveling, transmits the measured smoothness to a communication center through a vehicle communication device, and transmits the smoothness from the communication center to another vehicle is known from JP 2002-8198 A. Specifically, in the road surface information distribution system, a tire rotational speed is periodically measured, the road smoothness is measured based on the tire rotational speed, and a road smoothness level is quantified and transmitted to the communication center. With the road surface information distribution system described above, when the vehicle passes a location where information has already been acquired, vehicle movement control is performed that takes the acquired road smoothness level into account, so that vehicle slipping and turning can be better prevented.

[0004] From US 2009 / 0 105 921 A1 a vehicle risk avoidance device according to the preamble of claim 1 or claim 3 is known.

[0005] To detect road slipperiness based on the rotational speed of a tire in a vehicle, there is no need to create a difference between the rotational speed of the tire and the vehicle body speed, for example, due to wheel slippage caused by braking. This makes it difficult to detect road slipperiness at a high frequency while the vehicle is moving, making it impossible to detect slipperiness over a wide area of ​​the road while driving.

[0006] It is an object of the present invention to provide a vehicle risk avoidance device capable of detecting a road surface condition in a wider range and appropriately performing control for avoiding a risk during travel based on a road surface condition.

[0007] This object is achieved by the features of claim 1 and claim 3, respectively. Advantageous further developments are defined in the subclaims.

[0008] According to one aspect of the present invention, a vehicle risk avoidance device for performing risk avoidance control for a vehicle comprises: a tire sensor mounted on a rear surface of a tire of the vehicle and including a vibration detection unit for outputting a detection signal corresponding to a magnitude of vibration of the tire, a signal processing unit for detecting a road surface condition according to vibration data represented by the detection signal of the vibration detection unit, and a transmission unit for transmitting road surface data indicating the road surface condition; and a vehicle body-side system mounted on a vehicle body and including a receiver for receiving the road surface data transmitted from the transmission unit,a vehicle communication device for transmitting the road surface data to a communication center that collects road information, and obtaining the road surface data indicating the road surface condition of a road on which the vehicle is to travel from the communication center, a road information obtaining unit for obtaining road information, a position information obtaining unit for obtaining a current position of the vehicle, and a vehicle speed obtaining unit for obtaining a vehicle speed as a speed of the vehicle, wherein the vehicle body-side system further comprises a control unit that calculates the risk to the vehicle based on the road information obtained by the road information obtaining unit, the current position obtained by the position information obtaining unit,the vehicle speed obtained by the vehicle speed determination unit and the road surface data obtained from the communication center, and performs a control to avoid the risk to the vehicle when the control unit determines that there is a risk to the vehicle. If the road surface data is determined by the communication center, the control unit determines the risk to the vehicle based on the road surface data obtained from the communication center; and if the road surface data is not determined by the communication center, the control unit determines the risk to the vehicle based on the road surface data obtained from the tire sensor. The vehicle risk avoidance device is characterized in thatthat the control unit determines the risk to the vehicle according to a map or a relationship expression indicating a relationship between the risk to the vehicle, a vehicle speed, curve information from the road information, and a road surface friction coefficient from the road surface data; the signal processing unit includes: a ground contact portion identification unit that identifies a ground contact portion during rotation of the tire where a part of the tire corresponding to an arrangement position of the vibration detection unit contacts a ground; and a high-frequency level calculation unit for calculating a level of a high-frequency component of the detection signal in the ground contact portion; and the transmission unit transmits a calculation result of the level of the high-frequency component as the road surface data,which indicate the road surface condition.

[0009] In this way, the road surface condition is detected by the tire sensor, and the risk to the vehicle is determined based on the road surface data indicating the detection result. Specifically, the road surface data transmitted by the tire sensor is transmitted to the communication center to collect more accurate road surface data, so that the vehicle receives more accurate road surface data from the communication center. The risk to the vehicle is determined based on the received, more accurate road surface data.

[0010] By detecting the road surface condition using the tire sensor in this way, the road surface condition can be detected without braking. Therefore, since the road surface condition is detected at a higher frequency, it can be detected over a wider range, and appropriate control can be performed to avoid risk during driving based on the road surface condition.

[0011] The above and other objects, features, and advantages of the present invention will become apparent from the following detailed description with reference to the accompanying drawings. In the drawings: Fig. 1 is a diagram showing a block configuration of a state in which a vehicle risk avoidance device is mounted in a vehicle according to a first embodiment. Fig. 2 is a block diagram showing information transmission in the vehicle risk avoidance device. Fig. 3 a block diagram of a tire sensor. Fig. 4 a schematic cross-sectional view of a tire to which the tire sensor is attached. Fig. 5 is an output voltage waveform diagram of an acceleration sensor during rotation of a tire. Fig. 6A is a characteristic curve showing a change in the output voltage of the acceleration sensor when driving on a high-µ road surface whose road surface friction coefficient (hereinafter referred to as µ) is relatively large, such as an asphalt road. Fig. 6B is a characteristic curve showing a change in the output voltage of the acceleration sensor when driving on a low-p road surface whose road surface µ is relatively small, such as a frozen road. Fig. 7 is a characteristic curve showing results of a frequency analysis of the output voltage in a ground contact section when driving on both the high-µ road surface and the low-p road surface. Fig. 8 a flowchart of a road surface data transmission process. Fig. 9 a flowchart of a risk management process.

[0012] Embodiments of the present invention are described below with reference to the drawings. In the following description of embodiments, parts that are identical or equivalent are designated by the same reference numerals. (First embodiment)

[0013] Next, a vehicle risk avoidance device 100 according to the present embodiment is described with reference to FIG. Fig. 1 to 9. The vehicle risk avoidance device 100 according to the present embodiment estimates a road surface condition during travel based on vibrations transmitted to treads of tires of individual wheels of a vehicle, transmits an estimation result to a communication center, notifies of a risk to the vehicle, and performs vehicle movement control based on the road surface condition.

[0014] As it is in the Fig. 1 and Fig. As shown in FIG. 2, the vehicle risk avoidance device 100 includes tire sensors 1 arranged on the wheel side, and a vehicle body-side system 2 having respective components arranged on the vehicle body side. The vehicle body-side system 2 includes a receiver 21, an electronic control device for navigation control (hereinafter referred to as navigation ECU) 22, an electronic control device for brake control (hereinafter referred to as brake ECU) 23, a vehicle communication device 24, a notification device 25, and the like.

[0015] The vehicle risk avoidance device 100 transmits data representing a road surface condition during travel, such as data representing a road surface μ between tire 3 and a road surface on which the vehicle is traveling, from the tire sensors 1. Hereinafter, the road surface μ data is referred to as μ data, and the data representing the road surface condition is referred to as road surface data. In the case of the present embodiment, the vehicle risk avoidance device 100 transmits, as shown in Fig. 2, after the receiver 21 receives the road surface data transmitted from the tire sensor 1, it transmits this road surface data to a communication center 200 via the vehicle communication device 24. Conversely, the vehicle risk avoidance device 100 receives more accurate road surface data from the communication center 200 via the vehicle communication device 24. The vehicle risk avoidance device 100 determines the risk to the vehicle with the aid of the receiver 21 based on the more accurate road surface data obtained from the communication center 200 and various information transmitted from the navigation ECU 22 and the ECU 23.When it is determined that there is a risk to the vehicle, the vehicle risk avoidance device 100 transmits the determination result from the receiver 21 to the notification device 25 or the like, and notifies the notification device 25 or the like of the risk and the like. Specifically, the tire sensor 1 and the receiver 21 are configured as follows.

[0016] As it is in Fig. 3, each of the tire sensors 1 comprises an acceleration sensor 11, a temperature sensor 12, a control unit 13, an RF circuit 14 and a power supply 15. As shown in Fig. 4, the tire sensor 1 is arranged on a rear surface of a tread 31 of the tire 3.

[0017] The acceleration sensor 11 forms a vibration detection unit for detecting vibration transmitted to the tire. For example, the acceleration sensor 11 outputs an acceleration detection signal as the detection signal corresponding to vibration in a direction intersecting a circular path on which the tire sensor 1 rotates when the tires 3 rotate, that is, in a tire tangential direction indicated by an arrow X in Fig. 4 is shown.

[0018] The temperature sensor 12 outputs the detection signal corresponding to the temperature and measures a temperature of the road surface by detecting a temperature at a position of the tire 3 where the tire sensor 1 is arranged. The control unit 13 corresponds to a signal processing unit, uses the detection signal of the acceleration sensor 11 as a detection signal indicative of vibration data in the tire tangential direction, processes the detection signal to obtain road surface data, and transmits the obtained data to the RF circuit 14. Specifically, the control unit 13 extracts a ground contact portion of the acceleration sensor 11 while the tire 3 is rotating based on the detection signal of the acceleration sensor 11, that is, a temporary change in the output voltage of the acceleration sensor 11.The term "ground contact portion" as used in the present invention means a portion where a part of the tread 31 of the tire 3 corresponding to a position where the acceleration sensor 11 is arranged is in contact with the road surface. Since, in the present embodiment, the arrangement position of the acceleration sensor 11 is set as the arrangement position of the tire sensor 1, the ground contact portion means the portion where the part of the tread 31 of the tire 3 corresponding to the arrangement position of the tire sensor 1 is in contact with the road surface.

[0019] Since a high-frequency component included in the detection signal of the acceleration sensor 11 in the ground contact portion indicates the road surface condition, as described later, the control unit 13 extracts the high-frequency component from the detection signal and detects the road surface condition such as the road surface µ based on the extracted high-frequency component.

[0020] Further, in the present embodiment, since the temperature of the road surface is measured by the temperature sensor 12, the control unit 13 detects the road surface condition based on the temperature of the road surface, corrects the road surface condition obtained from the high frequency component of the detection signal from the acceleration sensor 11, and the like.

[0021] In this way, when detecting the road surface condition, the control unit 13 generates road surface data indicating the road surface condition and transmits the generated road surface data to the RF circuit 14, which transmits the road surface data to the receiver 21.

[0022] Specifically, the control unit 13 includes a known microcomputer including a CPU, a ROM, a RAM, an I / O interface, and the like, and performs the above-described processing according to the programs stored in the ROM, etc. The control unit 13 includes a section extraction unit 13a, a level calculation unit 13b, and a data generation unit 13c as functional units that perform these processes.

[0023] The section extraction unit 13a extracts the ground contact section by detecting a peak value of the detection signal represented by the output voltage of the acceleration sensor 11. An output voltage waveform of the acceleration sensor 11 during rotation of the tire is shown, for example, in Fig. 5. As shown in the figure, at a ground contact start time, when a part of the tread 31 corresponding to the arrangement position of the acceleration sensor 11 comes into contact with the ground during the rotation of the tire 3, the output voltage of the acceleration sensor 11 reaches a local maximum value. The section extraction unit 13a detects the ground contact start time when the output voltage of the acceleration sensor 11 reaches the local maximum value as a first peak value time. Further, as shown in Fig. 5, at a ground contact termination time point at which, during rotation of the tire 3, a state in which the portion of the tread 31 corresponding to the arrangement position of the acceleration sensor 11 comes into contact with the ground changes to a state in which the portion is no longer in contact with the ground, a local minimum value is detected. The portion extraction unit 13a detects the ground contact termination time point at which the output voltage of the acceleration sensor 11 reaches the local minimum value as a second peak value time point.

[0024] The reason why the output voltage of the acceleration sensor 11 reaches the peak values ​​at the above-described time is described below. In other words, when the part of the tread 31 corresponding to the installation position of the acceleration sensor 11 comes into contact with the ground in conjunction with the rotation of the tire 3, a portion of the tire 3, which until then had a substantially cylindrical surface in the vicinity of the acceleration sensor 11, is compressed and deformed into a flat shape. When an impact occurs at the time of deformation, the output voltage of the acceleration sensor 11 reaches the first peak value.When the portion of the tread 31 corresponding to the mounting position of the acceleration sensor 11 detaches from the ground contact surface in association with the rotation of the tire 3, the pressure on the tire 3 decreases, and it returns from the flat shape in the vicinity of the acceleration sensor 11 to the substantially cylindrical shape. When the tire 3 returns to its original shape upon impact, the output voltage of the acceleration sensor 11 reaches the second peak value. As described above, the output voltage of the acceleration sensor 11 reaches the first and second peak values ​​at the ground contact initiation time and the ground contact termination time, respectively. Since the direction of impact when the tire 3 is pressed in a direction opposite to a direction of impact when the pressure on the tire 3 is released, the output voltage values ​​are opposite to each other.

[0025] Subsequently, the section extraction unit 13a extracts the ground contact section of the acceleration sensor 11 by extracting the data of the detection signal including the timings of the first and second peak values, and transmits that the acceleration sensor 11 is located in the ground contact section to the level calculation unit 13b.

[0026] Since the timing at which the output voltage of the acceleration sensor 11 reaches the second peak value is set to the ground contact termination timing of the acceleration sensor 11, the section extraction unit 13a transmits a transmission trigger signal to the RF circuit 14 at this time. As a result, the RF circuit 14 transmits the road surface data such as the μ data generated by the level calculation unit 13b as described below. As described above, since the data transmission by the RF circuit 14 is not always performed but only performed at the ground contact termination timing of the acceleration sensor 11, power consumption can be reduced.

[0027] When the level calculation unit 13b receives from the section extraction unit 13a that the acceleration sensor 11 is located in the ground contact section, it calculates the level of the high-frequency component caused by the vibration of the tire 3 in the output voltage of the acceleration sensor 11 during the ground contact section. Then, the level calculation unit 13b notifies the data generation unit 13c of the calculation result as the road surface data such as the μ data. The level calculation unit 13b calculates the level of the high-frequency component as an index indicating the road surface condition such as the road surface μ, with a reason for the calculation being with reference to the Fig. 6A, Fig. 6B and Fig. 7 is described.

[0028] Fig. 6A shows a change in the output voltage of the acceleration sensor 11 when driving on a high-µ road surface whose road surface µ is relatively large, such as an asphalt road. Fig. 6B shows a change in the output voltage of the acceleration sensor 11 when driving on a low-µ road surface whose road surface µ is relatively small and comparable to that of a frozen road.

[0029] As shown in the figures, the first and second peak values ​​appear at the beginning and end of the ground contact section, that is, at the ground contact start time and the ground contact end time of the acceleration sensor 11, regardless of the road surface μ. However, the output voltage of the acceleration sensor 11 changes due to an influence of the road surface μ. For example, when the road surface μ is low, such as when driving on the low-μ road surface, a slight high-frequency vibration due to slippage of the tire 3 is superimposed on the output voltage. A slight high-frequency signal due to the slippage of the tire 3, as described above, is also excessively superimposed on the output voltage when the road surface μ is high, such as when driving on the high-μ road surface.

[0030] For this reason, in both the case of high-µ road surface and low-µ road surface, when the frequency analysis of the output voltage in the ground contact section is performed, the Fig. 7. In other words, in a low-frequency band, a high level is achieved both when driving on the high-μ road surface and when driving on the low-μ road surface. However, in a high-frequency band of 1 kHz or higher, the level when driving on the low-p road surface is higher than that when driving on the high-μ road surface. For this reason, the level of the high-frequency component of the output voltage of the acceleration sensor 11 serves as an index indicating the road surface condition.

[0031] Therefore, the level of the high-frequency component of the output voltage of the acceleration sensor 11 in the ground contact section is calculated by the level calculation unit 13b, allowing the calculated level to be set as the μ data. Furthermore, the road surface type corresponding to the road surface μ can be detected as the road surface condition, for example, by determining the road surface as a frozen road when the road surface μ is low according to the μ data.

[0032] For example, the level of the high-frequency component can be calculated by extracting the high-frequency component from the output voltage of the acceleration sensor 11 and integrating the extracted high-frequency component in the ground contact section. Specifically, the high-frequency components of the frequency bands fa to fb, which are assumed to change according to the road surface condition and the road surface μ, are extracted by filtering or the like, and the voltages of the high-frequency components of the frequency bands fa to fb extracted by frequency analysis are integrated together. For example, a capacitor, not shown, is charged. With the above configuration, the amount of charge when the road surface μ is higher, such as when traveling on the high-μ road surface, is larger than that when the road surface μ is lower, such as when traveling on the low-μ road surface.Using the load amount as the µ-data, the road surface µ can be estimated such that the larger the load amount indicated by the µ-data, the lower the road surface µ is.

[0033] Essentially, the data generation unit 13c generates the road surface data based on the calculation result of the level calculation unit 13b. For example, the data generation unit 13c uses the unaltered μ data as the road surface data, or obtains the road surface condition such as the frozen road and the asphalt road according to the μ data, and generates the data indicative of the road surface condition as the road surface data.

[0034] Furthermore, as described above, in the present embodiment, the temperature of the road surface is measured by the temperature sensor 12. Based on the measured temperature, the data generation unit 13c obtains the road surface temperature by receiving the detection signal of the temperature sensor 12, detects the type of road surface according to the obtained road surface temperature, and corrects the μ-data or the type of road surface obtained from the μ-data.

[0035] For example, when the road surface temperature detected by the temperature sensor 12 is below zero, the data generation unit 13c detects that the road surface is frozen as the road surface type. Further, when the μ-data obtained from the high-frequency component of the detection signal from the acceleration sensor 11 or the road surface type indicated by the μ-data does not match the road surface temperature detected by the temperature sensor 12, the data generation unit 13c corrects the mismatched data or the mismatched type, or does not use the mismatched data or the mismatched type as a detection result of the road surface condition.For example, if the road surface type obtained from the high-frequency component of the detection signal of the acceleration sensor 11 indicates a frozen state, and at the same time, the road surface temperature detected by the temperature sensor 12 is 40°C, there may be an error in the detection result of the road surface type being in a frozen state. In this case, the data generation unit 13c does not use the result transmitted from the level calculation unit 13b as the road surface type detection result.Similarly, when the road surface µ indicated by the µ data does not agree with the road surface type obtained from the road surface temperature, for example, when the road surface µ indicated by the µ data is high although the road surface type is detected as the frozen state based on the road surface temperature, the road surface µ indicated by the µ data is corrected and set to a value lower than that before the correction.

[0036] The RF circuit 14 constitutes a transmission unit that transmits the road surface data, such as the μ-data transmitted from the data generation unit 13c, to the receiver 21. Communication between the RF circuit 14 and the receiver 21 can be implemented using a known short-range wireless communication technology such as Bluetooth (registered trademark). The timing at which the road surface data is transmitted is arbitrary, but in the present embodiment, as described above, the transmission trigger signal is transmitted from the section extraction unit 13a at the ground contact termination time of the acceleration sensor 11 to transmit the road surface condition data from the RF circuit 14.As described above, since the data transmission by the RF circuit 14 is not always performed but only at the ground contact completion time of the acceleration sensor 11, the power consumption can be reduced.

[0037] The road surface data is transmitted along with unique identification information (hereinafter referred to as "ID information") to the tire 3 of each wheel with which the vehicle was previously equipped. Since the positions of each wheel can be identified by a known wheel position detecting device for detecting the respective positions on the vehicle where each wheel is mounted, the road surface data is transmitted along with the ID information to the receiver 21, making it possible to associate the data with the respective wheels.

[0038] On the other hand, the receiver 21 receives the road surface data transmitted from the tire sensor 1 and performs processing to output the road surface data to the vehicle communication device 24. Based on the above-described processing, the road surface data is transmitted from the vehicle communication device 24 to the communication center 200, which collects the road information and the like.

[0039] Further, the receiver 21 performs a process of acquiring the more accurate road surface data from the communication center 200 via the vehicle communication device 24. Furthermore, the receiver 21 also performs a process of acquiring information about the road to be traveled, such as curve information about a curve (hereinafter referred to as radius information), from the navigation ECU 22, and further acquires vehicle speed information from the brake ECU 23. The receiver 21 extracts the road surface data of the road to be traveled from the road surface data acquired from the communication center 200, and determines the risk to the vehicle based on the road surface data, the road information acquired from the navigation ECU 22, and the vehicle speed information obtained from the brake ECU 23.In other words, since the road surface data transmitted from the communication center 200 includes data about roads on which the vehicle is scheduled to travel, the receiver 21 determines the risk to the vehicle based on the data at a location where the vehicle is scheduled to travel. If the determination result indicates that there is a risk to the vehicle, the receiver 21 performs various processes according to the risk to the vehicle.

[0040] For example, when the receiver 21 determines that there is a risk to the vehicle, it transmits a control signal to the notification device 25 to inform of this fact. Furthermore, the receiver 21 outputs a request signal to perform vehicle motion control to generate a braking force acting on the vehicle by sending a braking request to the brake ECU 23 when necessary.

[0041] Specifically, the receiver 21 stores the radius information corresponding to a change in the road surface μ and a map or a functional expression indicating a relationship between a vehicle speed and the risk to the vehicle, and the receiver 21 determines the risk to the vehicle based on the map or a functional expression corresponding to the road surface μ specified by the road surface data. For example, in the map or the functional expression, the relationship between a curve radius of the road and a vehicle speed at which the vehicle can negotiate the curve is determined for each road surface μ, and as the road surface μ decreases, the vehicle speed at which the vehicle can negotiate a curve with the same curve radius decreases.When the receiver 21 continues to travel at the current vehicle speed using the map or the relationship expression as described above, the receiver 21 determines whether or not the vehicle can negotiate the road on which it is to travel, determines that there is no risk to the vehicle if the vehicle can negotiate the curve, and determines that there is a risk to the vehicle if the vehicle cannot negotiate the curve.

[0042] As described above, in this example, the map or relationship expression corresponding to the road surface μ is used to determine the risk to the vehicle. Alternatively, a map or relationship expression corresponding to the road surface type may also be used. Furthermore, the risk to the vehicle can be determined not only based on the relationship between the curve radius of the road curve and the vehicle speed, but also only from a relationship between the road surface μ and the vehicle speed. For example, since the lower the road surface μ is, the longer the braking distance becomes, it is determined that there is a risk to the vehicle when the braking distance assumed with the road surface μ and the vehicle speed is long.Thus, the risk to the vehicle can be determined based on information other than the curve radius of the road and the vehicle speed.

[0043] The navigation ECU 22 is located in the navigation system and acquires information from a non-transitory, tangible storage medium such as a memory that stores road information and the like, and measures the current position of the vehicle based on the position information from a GPS (Global Positioning System) satellite. In other words, the navigation ECU 22 performs various processes related to road guidance and the like. The vehicle risk avoidance device 100 according to the present embodiment uses road information and current position information processed by the navigation ECU 22. Specifically, as described, the road information is used to determine the risk to the vehicle and is transmitted from the navigation ECU 22 to the receiver 21.The current position information is transmitted from the navigation ECU 22 to the vehicle communication device 24, and when the road surface data is transmitted from the vehicle communication device 24 to the communication center 200, the current position information is transmitted along with it. As a result, the communication center 200 can determine from which position the road surface μ or the road surface type indicated by the road surface data is derived.

[0044] The navigation ECU 22 described above is an example of the road information acquisition unit that acquires the road information and the position information acquisition unit that acquires the current position information. Alternatively, a device other than the navigation ECU 22 may be used. For example, a mobile device such as a cellular phone may exchange information with the respective units of the vehicle body-side system 2, and the mobile device may be used as the road information acquisition unit or the position information acquisition unit. Further, an installation position of the communication system for communicating with the communication center 200, which may be installed at any location such as a road, may be set as the current position of the vehicle.

[0045] The brake ECU 23 constitutes a brake control device that performs various brake controls. The brake ECU 23 can control a brake fluid pressure control actuator to automatically generate the brake fluid pressure and pressurize a wheel cylinder to generate a braking force. Furthermore, the brake ECU 23 can independently control the braking force of each wheel. Therefore, when a braking request is issued from the receiver 21 upon determining that there is a risk to the vehicle, a desired braking force is generated for the wheel to be braked, so that the braking force can be generated for the vehicle. Furthermore, the brake ECU 23 calculates a vehicle speed based on a detection signal from a wheel speed sensor (not shown) or the like, and transmits the calculation result as vehicle speed information to the receiver 21.In this example, the brake ECU 23 serves as the vehicle speed detection unit. Alternatively, the vehicle speed can be obtained by means other than the brake ECU 23.

[0046] The vehicle communication device 24 is suitable for communication between the road and the vehicle and exchanges information with the communication center 200 via a communication system (not shown) installed, for example, on a road or the like. In the present embodiment, the vehicle communication device 24 transmits the road surface data transmitted from the receiver 21 to the communication center 200 and receives the more accurate road surface data from the communication center 200. The notification device 25 comprises, for example, a gauge display device and is used to inform a driver of a risk to the vehicle. When the notification device 25 is equipped with the gauge display device, the notification device 25 is arranged where the driver can see it while driving and is, for example, installed in an instrument panel of the vehicle. When a control signal indicating that a risk to the vehicle exists is received from the receiver 21, the gauge display device displays the risk in such a way that an assessment of the nature of the risk is possible, thereby being suitable for informing the driver of the risk.

[0047] The notification device 25 may further include a buzzer, a voice guidance device, or the like. In this case, the notification device 25 may acoustically inform the driver of the risk through a buzzer sound or voice guidance. Furthermore, although the meter display device is described as the notification device 25 for visually transmitting information, the notification device 25 may also be configured as a display unit such as a head-up display that displays information.

[0048] The vehicle risk avoidance device 100 according to the present embodiment is configured as described above. Note that the respective units of the vehicle body-side system 2 are connected to each other via, for example, an on-board LAN (local area network) such as a CAN (controller area network). Therefore, the respective units can exchange information with each other via the on-board LAN.

[0049] On the other hand, the communication center 200, which exchanges information about the road surface data with the vehicle risk avoidance device 100, collects the road information and delivers the road information to the vehicles or the like. The communication center 200 can communicate with the vehicle communication device 24 either directly or via the communication system installed at an arbitrary location, such as a road.

[0050] In the present embodiment, the communication center 200 manages information about the road surface condition at each location of each road in the map data as a database and maps the road surface condition that is constantly changing based on the received road surface data. In other words, the communication center 200 updates the information about the road surface condition at each location of each road in the map data based on the received road surface data. The communication center 200 delivers the road surface data from the database to the vehicle.

[0051] Specifically, the communication center 200 collects the road surface data of the road on which the vehicle is traveling, transmitted from the vehicle, and updates the road surface data of each road in the map data based on the road surface data. Furthermore, the communication center 200 also collects weather information and the like, corrects the respective road surface data based on the weather information and the like, and updates the respective road surface data as more reliable road surface data. For example, the communication center 200 acquires information about a snow accumulation amount and a frozen road surface as the weather information, and updates the corresponding road surface data regarding the snow-covered road surface and the frozen road surface, thereby sequentially storing the more accurate road surface data.The communication center 200 delivers the road surface data stored in the database to the vehicle, thereby providing more accurate road surface data to the vehicle. At this time, each vehicle can acquire not only the road surface data of the current position but also the road surface data of the road on which the vehicle is to travel, because the communication center 200 collects the road surface data of a large number of vehicles and updates the road surface data of the respective roads in the map data stored in the database. The following describes the operation of the vehicle risk avoidance device 100 according to the present embodiment with reference to the figures shown in FIGS. Fig. 8 and Fig. 9 shown flowcharts.

[0052] First, in the tire sensor 1 of each wheel, the control unit 13 extracts a high-frequency component from the detection signal of the acceleration sensor 11, i.e., the output voltage, and detects the road surface μ and the road surface type based on the extracted high-frequency component during ground contact. Subsequently, the road surface data including the μ data indicating the road surface μ or the road surface type is generated, and a frame in which the road surface data is stored is transmitted to the receiver 21 via the RF circuit 14.

[0053] Based on the above-mentioned road surface data, the vehicle body-side receiver 21 exchanges the road surface data as described in Fig. 8. Specifically, in step S100, the receiver 21 receives the frame, receives the road surface data from the tire sensor 1, and in step S110, reads the information about the µ data indicating the road surface µ and the road surface type from the road surface data to detect the road surface condition such as the road surface µ or the road surface type. Subsequently, in step S120, the extracted data or the received road surface data, as it is or converted into a predetermined protocol, is transmitted to the vehicle communication device 24. As a result, the road surface data indicating the road surface µ detected by the vehicle, the road surface type, and the like are transmitted to the communication center 200.As a result, the communication center 200 adds the weather information and the like and updates the road surface data of each road in the map data managed as the database to the most recent data. The more accurate road surface data after the database update is transmitted from the communication center 200 to the vehicle.

[0054] Furthermore, the recipient 21 also carries out a Fig. 9 based on the road surface data. First, in step S200, the risk to the vehicle is determined based on the road surface data.

[0055] In other words, since the road surface data transmitted from the communication center 200 includes data about roads on which the vehicle is to travel, the receiver 21 determines the risk to the vehicle based on the data about a location the vehicle is to pass. For example, as described above, the receiver 21 determines the risk to the vehicle based on the map or the relationship expression corresponding to the road surface μ indicated by the road surface data. In this example, if it is determined that there is a risk to the vehicle, the process proceeds to step S210 to output a control signal instructing the notification device 25 to notify that there is a risk to the vehicle.Furthermore, the receiver 21 outputs, as needed, a request signal for performing vehicle motion control to generate a braking force acting on the vehicle by transmitting a braking request to the brake ECU 23. At this time, a braking request can be issued according to the type of risk, so that braking force can be generated for all wheels or for a specific wheel to prevent the vehicle from skidding.

[0056] This allows the driver to take appropriate measures, such as decelerating the vehicle, based on the notification of the risk by the notification device 25. Furthermore, even if the driver cannot immediately address the risk to the vehicle, the risk to the vehicle can be avoided by vehicle movement control to avoid the risk to the vehicle, if necessary.

[0057] As described above, in the vehicle risk avoidance device 100 according to the present embodiment, the road surface condition such as the road surface μ and the road surface type is detected by the tire sensor 1, and the risk to the vehicle is determined based on the road surface data indicating the detection result. Specifically, the road surface data transmitted from the tire sensor 1 is transmitted to the communication center 200 to collect more accurate road surface data, so that the vehicle receives the more accurate road surface data from the communication center 200. The risk to the vehicle is determined based on the received more accurate road surface data.

[0058] When the road surface condition is detected using the tire sensor 1 in this way, the road surface condition can be detected without braking. Therefore, since the road surface condition can be detected at a higher frequency, the road surface condition can be detected over a wider range, and the control for avoiding the risk during travel based on the road surface condition can be performed more appropriately. (Second embodiment)

[0059] In the present embodiment, the process to be performed by the receiver 21 is changed compared to the first embodiment, but the other processes are the same as in the first embodiment. Therefore, only the parts that are different from those in the first embodiment will be described below. As described above, in the first embodiment, the receiver 21 determines the risk to the vehicle based on the road surface data transmitted from the communication center 200. However, in the present embodiment, the receiver 21 determines whether or not there is a risk to the vehicle not based on the road surface data transmitted from the communication center 200, but based on the road surface data indicating the road surface condition detected by the tire sensor 1 of the host vehicle. Specifically, the road surface data transmitted from the tire sensor 1 is used when the process for determining the risk to the vehicle in step S200 in Fig. 9 is executed.

[0060] This makes it possible to determine the risk to the vehicle based on the road surface condition detected in real time, without waiting for the road surface data from the communication center 200. In particular, the above-described configuration is effective when the vehicle is traveling in an area where it is difficult to communicate with the communication center 200, because the risk to the vehicle can be determined based only on the road surface data detected by the host vehicle.

[0061] Furthermore, in the present embodiment, the receiver 21 also transmits the road surface data indicating the road surface condition detected by the tire sensor 1 to the communication center 200. For this reason, in the communication center 200, the road surface data that are constantly changing can be mapped based on the road surface data transmitted from the vehicle. (Other embodiments)

[0062] The present invention is not limited to the embodiments described above, but encompasses various modifications within the scope defined by the claims. Furthermore, it is clear that various combinations or aspects, or other combinations or aspects in which only one element, one or more elements, or one or fewer elements are added to the various combinations or aspects, are also within the scope or technical idea of ​​the present invention. For example, the first embodiment and the second embodiment described above are not independent of each other and can be combined with each other. For example, when the vehicle communication device 24 and the communication center 200 can be combined with each other, the risk to the vehicle is determined based on the road surface data transmitted from the communication center 200, as in the first embodiment. When a situation in which communication between the vehicle communication device 24 and the communication center 200 cannot be performed for a predetermined period of time continues, the risk to the vehicle is determined based on the road surface data transmitted from the tire sensor 1 of the host vehicle, as in the second embodiment.With the above configuration, when communication between the vehicle communication device 24 and the communication center 200 can be performed, the risk to the vehicle can be determined based on the more accurate road surface data, and even when communication cannot be performed, the risk to the vehicle can be determined based on the road surface data acquired by the host vehicle.

[0063] In the embodiment described above, the ground contact portion is identified based on the detection signal of the acceleration sensor 11 constituting the vibration detection unit, and the calculation result of the level of the high-frequency component in the detection signal in the ground contact portion is used as the road surface data indicating the road surface condition. However, this configuration shows only one example of a method for detecting the road surface condition using the detection signal by the vibration detection unit. However, the road surface condition may also be detected by another method using the detection signal by the vibration detection unit.

[0064] Furthermore, in the above-described embodiments, in addition to determining the risk to the vehicle based on the road information, current position information, vehicle speed, and road surface data transmitted from the communication center 200, the receiver 21 serves as a control unit for instructing the notification device 25 to notify the risk to the vehicle. However, this configuration is only an example, and a control unit may also be arranged separately from the receiver 21, or another ECU such as the navigation ECU 22 or the brake ECU 23 may serve as the control unit.

Claims

[1] A vehicle risk avoidance device (100) for performing a control for avoiding a risk for a vehicle, the vehicle risk avoidance device (100) comprising: a tire sensor (1) mounted on a rear surface of a tire (3) of the vehicle and comprising a vibration detection unit (11) for outputting a detection signal corresponding to a magnitude of vibration of the tire (3), a signal processing unit (13) for detecting a road surface condition according to vibration data represented by the detection signal of the vibration detection unit (11), and a transmission unit (14) for transmitting road surface data indicating the road surface condition; and a vehicle body-side system (2) arranged on a vehicle body and comprising a receiver (21) for receiving the road surface data transmitted from the transmission unit (14), a vehicle communication device (24) for transmitting the road surface data to a communication center (200) that collects road information, and obtaining road surface data indicating the road surface condition of a road on which the vehicle is to travel from the communication center (200), a road information obtaining unit (22) for obtaining road information, a position information obtaining unit (22) for obtaining a current position of the vehicle, and a vehicle speed obtaining unit (23) for obtaining a vehicle speed as a speed of the vehicle, wherein: the vehicle body-side system (2) further comprises a control unit (21) that determines the risk to the vehicle based on the road information obtained by the road information obtaining unit (22), the current position obtained by the position information obtaining unit (22), the vehicle speed obtained by the vehicle speed obtaining unit (23), and the road surface data obtained from the communication center (200), and performs control to avoid the risk to the vehicle when the control unit (21) determines that there is a risk to the vehicle; when the road surface data is obtained from the communication center (200), the control unit (21) determines the risk to the vehicle based on the road surface data obtained from the communication center (200); and if the road surface data is not obtained from the communication center (200), the control unit (21) determines the risk to the vehicle based on the road surface data obtained from the tire sensor (1); characterized by , that: the control unit (21) determines the risk to the vehicle according to a map or a relationship expression indicating a relationship between the risk to the vehicle, a vehicle speed, curve information from the road information, and a road surface friction coefficient from the road surface data; the signal processing unit (13) comprises: a ground contact portion identifying unit (13a) that identifies a ground contact portion upon rotation of the tire (3) where a part of the tire (3) corresponding to an arrangement position of the vibration detecting unit (11) contacts a ground; and a high-frequency level calculation unit (13b) for calculating a level of a high-frequency component of the detection signal in the ground contact portion; and the transmission unit (14) transmits a calculation result of the level of the high frequency component as the road surface data indicating the road surface condition. [2] Vehicle risk avoidance device (100) according to claim 1, wherein: the vehicle communication device (24) transmits the road surface data transmitted by the tire sensor (1) to the communication center (200); and when the road surface information in a database of map data is updated by the communication center (200) based on the road surface data, the vehicle communication device (24) obtains the road surface data indicating the road surface condition of the road on which the vehicle is to travel from the updated database. [3] A vehicle risk avoidance device (100) that performs control to avoid a risk for a vehicle, the vehicle risk avoidance device (100) comprising: a tire sensor (1) mounted on a rear surface of a tire (3) of the vehicle and comprising a vibration detection unit (11) for outputting a detection signal corresponding to a vibration amount of the tire (3), a signal processing unit (13) for detecting a road surface condition according to vibration data given by the detection signal of the vibration detection unit (11), and a transmission unit (14) for transmitting road surface data indicating the road surface condition; and a vehicle body-side system (2) arranged on a vehicle body and comprising a receiver (21) for receiving the road surface data transmitted from the transmission unit (14), a road information acquisition unit (22) for obtaining the road information, a position information acquisition unit (22) for obtaining a current position of the vehicle, and a vehicle speed acquisition unit (23) for obtaining a vehicle speed as a speed of the vehicle, wherein: the vehicle body-side system (2) further comprises a control unit (21) that determines the risk to the vehicle based on the road information obtained by the road information obtaining unit (22), the current position obtained by the position information obtaining unit (22), the vehicle speed obtained by the vehicle speed obtaining unit (23) and the road surface data received by the receiver (21), and performs control to avoid the risk to the vehicle when the control unit (21) determines that there is a risk to the vehicle; characterized by , that: the control unit (21) determines the risk to the vehicle according to a map or a relationship expression indicating a relationship between the risk to the vehicle, a vehicle speed, curve information from the road information, and a road surface friction coefficient from the road surface data; the signal processing unit (13) comprises: a ground contact portion identifying unit (13a) that identifies a ground contact portion upon rotation of the tire (3) where a part of the tire (3) corresponding to an arrangement position of the vibration detecting unit (11) contacts a ground; and a high-frequency level calculation unit (13b) for calculating a level of a high-frequency component of the detection signal in the ground contact portion; and the transmission unit (14) transmits a calculation result of the level of the high frequency component as the road surface data indicating the road surface condition. [4] Vehicle risk avoidance device (100) according to one of claims 1 to 3, wherein: the vehicle body-side system (2) further comprises a notification device (25) that notifies a driver; and when the control unit (21) determines the risk to the vehicle, the control unit (21) controls the notification device (25) so that the notification device (25) executes the notification of the risk as the control for avoiding the risk to the vehicle. [5] Vehicle risk avoidance device (100) according to one of claims 1 to 4, wherein: the vehicle body-side system (2) further comprises a brake control device (23) that generates a braking force acting on a wheel to generate a braking force acting on the vehicle; and when the control unit (21) determines the risk to the vehicle, the control unit (21) outputs a braking request as control for avoiding the risk to the vehicle to the braking control device (23) to generate the braking force acting on the vehicle.

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