Road surface condition determination device and control device

Abstract

To provide a road surface condition determination device and control device, which enable highly accurate estimation of the road condition using a simple configuration.SOLUTION: A road surface condition determination device (10) disclosed herein is for determining the condition of a road surface a vehicle is traveling on, and comprises a data acquisition unit (131) for acquiring sound data, including information on reflections of noise generated by the vehicle, collected by a data collection unit installed on the vehicle, and a determination unit (132) configured to determine the condition of a road surface on the basis of the presence or absence of peaks in the acquired sound data in a predetermined frequency range.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a road surface condition determination device and a control device.

Background Art

[0002] Conventionally, in order for road administrators and the like to be able to perform traffic control, maintenance, repair, etc. without requiring much labor, technologies for grasping the road conditions have been proposed. For example, Patent Document 1 proposes a detection method for emitting ultrasonic waves toward the road surface, obtaining the acoustic impedance of the road surface from the reflectivity, and comparing it with a reference acoustic impedance to identify substances present on the road surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in an autonomous vehicle, from the viewpoint of safety, a determination may be made as to whether autonomous driving can continue according to road conditions. Therefore, there is a need for a technology that can accurately estimate the road surface condition while the vehicle is running. Here, the technology of Patent Document 1 requires a transmitter / receiver fixed to a support so that the distance to the road surface is known in order to emit and receive ultrasonic waves. Since the distance to the road surface changes during running of the vehicle, it is also difficult to retrofit a large device that emits ultrasonic waves to the vehicle body part. Therefore, it is difficult to apply the detection method of Patent Document 1 to a vehicle.

[0005] In view of such circumstances, an object of the present disclosure is to provide a road surface condition determination device and a control device that can estimate the road surface condition with high accuracy with a simple configuration.

Means for Solving the Problems

[0006] (1) A road surface condition determination device according to one embodiment of the present disclosure is a road surface condition determination device for determining the condition of a road surface on which a vehicle is traveling, comprising: a data acquisition unit that acquires sound data including information on reflected sound generated by the vehicle, which is collected by a data acquisition unit mounted on the vehicle; and a determination unit that determines the condition of the road surface based on the presence or absence of a peak in a predetermined frequency range in the acquired sound data. This configuration allows for highly accurate estimation of road surface conditions with a simple setup.

[0007] (2) In one embodiment of the present disclosure, in (1), the data acquisition unit acquires temperature data including information on the temperature around the road surface, and the determination unit further determines the condition of the road surface based on the temperature data. This configuration allows for the estimation of road surface conditions in even finer increments.

[0008] (3) In one embodiment of the present disclosure, in (1) or (2), the predetermined frequency range includes a specific frequency having the operating sound of the inverter provided in the vehicle. This configuration allows for highly accurate estimation of road surface conditions by using a frequency range that includes specific frequencies with minimal influence from noise during driving.

[0009] (4) In one embodiment of the present disclosure, in (3), the determination unit determines the condition of the road surface while the vehicle is in motion. This configuration makes it possible to detect strong reflected sound at specific frequencies, allowing for accurate estimation of road surface conditions.

[0010] (5) A control device according to one embodiment of the present disclosure is a control device mounted on a vehicle and controlling the vehicle, comprising: a data acquisition unit that acquires sound data including information on reflected sound generated by the vehicle, collected by a data acquisition unit mounted on the vehicle; and a determination unit that determines the condition of the road surface on which the vehicle is traveling based on the presence or absence of peaks in a predetermined frequency range in the acquired sound data, and controls the vehicle based on the determined condition of the road surface. This configuration allows for highly accurate estimation of road surface conditions with a simple setup. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide a road surface condition determination device and control device that can estimate road surface conditions with high accuracy using a simple configuration. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an example of a road surface condition determination system configuration, including a road surface condition determination device. [Figure 2] Figure 2 is another diagram showing an example configuration of the road surface condition determination system shown in Figure 1. [Figure 3] Figure 3 illustrates the frequency spectrum of sound in a vehicle. [Figure 4] Figure 4 is a flowchart illustrating the process for determining road surface conditions. [Figure 5] Figure 5 shows another example configuration of a road surface condition determination system, including a road surface condition determination device. [Modes for carrying out the invention]

[0013] A road surface condition determination device and control device according to one embodiment of the present disclosure will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals. In the description of this embodiment, the description of the same or corresponding parts will be omitted or simplified as appropriate.

[0014] Figures 1 and 2 show examples of the configuration of a road surface condition determination system. The road surface condition determination system includes a road surface condition determination device 10. Figure 1 is a block diagram including an example of the internal configuration of the road surface condition determination device 10. Figure 2 shows the overall configuration of the road surface condition determination system.

[0015] The road surface condition determination device 10 according to this embodiment is a device that determines the condition of the road surface on which a vehicle 20 is traveling. As will be described in detail later, the road surface condition determination device 10 determines (estimates) the road surface condition based on information of reflected sound generated by the vehicle 20. The road surface condition is the condition of the road surface and, in this embodiment, is classified into four categories: "Dry," "Wet," "Ice," and "Snow." The road surface condition is not limited to these four categories, and for example, some categories may be omitted, or categories such as distinguishing between paved roads and gravel roads may be further included. Dry indicates that the road surface is dry. Wet indicates that the road surface is wet. Ice indicates that the road surface is frozen. Snow indicates that the road surface is covered with snow. In addition, in this specification, sound is not limited to frequencies within the audible range, and for example, frequencies above 20 kHz are also included. Furthermore, operating sound refers to the sound produced when the device is operating, and includes noise.

[0016] The road surface condition determination device 10 comprises a communication unit 11, a storage unit 12, and a control unit 13. The control unit 13 comprises a data acquisition unit 131 and a determination unit 132. The road surface condition determination device 10 may be a computer as its hardware configuration. Details of the components of the road surface condition determination device 10 will be described later.

[0017] The road surface condition determination device 10 may form a road surface condition determination system together with at least one of devices (data collection unit 70 and in-vehicle communication unit 80) mounted on the vehicle 20 connected by the network 40. The network 40 is, for example, the Internet. Here, the vehicle 20 is not limited to a specific use, and may be, for example, a passenger car, a truck, a taxi, or a bus. In the present embodiment, the vehicle 20 will be described as an electric vehicle equipped with an autonomous driving function, but it may not have an autonomous driving function and may be, for example, a hybrid vehicle.

[0018] In the present embodiment, the vehicle 20 includes a data collection unit 70 and an in-vehicle communication unit 80. The data collection unit 70 collects sound data including information on the reflected sound of the sound generated in the vehicle 20. The data collection unit 70 is mounted on the vehicle 20 and includes a microphone in the present embodiment, but is not limited thereto. As will be described below, it is necessary to collect the intensity of the sound of a specific frequency as the sound data, but the data collection unit 70 may include a device capable of detecting the sound of a specific frequency other than the microphone. For example, the data collection unit 70 may be configured to include a cavity resonator, a resonator, or a pressure sensor instead of the microphone. For example, the cavity resonator may be an air column resonance device having a tube length that is 1 / 4 of the wavelength of a specific frequency. By using a cavity resonator or the like instead of the microphone, the cost of the data collection unit 70 may be reduced.

[0019] As shown in Figure 2, in this embodiment, the microphone, which is the data acquisition unit 70, is mounted on the vehicle 20 facing the road surface to pick up reflected sound from the road surface. Here, Figure 3 is a diagram illustrating the frequency spectrum of sound in the vehicle 20. The vertical axis represents signal strength (sound intensity). The horizontal axis represents frequency. The sound in the vehicle 20 includes sounds of various frequencies, mainly sound emitted from the vehicle 20 and reflected from the road surface, as well as noise during driving, but has different characteristics depending on the road surface condition. As shown in Figure 3, in Dry and Ice conditions, peaks (sharp changes such as P1 and P2) that are not present in Wet and Snow conditions are observed. The inventors' more detailed analysis revealed that when the road surface condition is Dry or Ice, there is a peak (P1) at a specific frequency included in the high-frequency range, and that even when the vehicle 20 is driving, the peak (P1) can be detected without being significantly affected by noise such as driving sound. Here, the high-frequency range is not limited to a specific frequency band, but is generally 5 kHz or higher. In the Dry test, another peak (P2) is also observed, but it is at a low frequency, not in the high-frequency range, and may not be detectable due to the influence of noise such as road noise. Further analysis by the inventor revealed that the peak (P1) at a specific frequency is largely due to the operating noise of the inverter 21 (see Figure 2) installed in the vehicle 20. The inverter 21 is a device that converts DC power from the battery into AC power to drive the motors installed in the tires 30. Because there are individual differences in the operating noise of the inverter 21, the specific frequency may vary depending on the vehicle 20, but the specific frequency is generally in the range of a few kHz to a dozen kHz. Therefore, by collecting sound data with the data acquisition unit 70, it is possible to determine the road surface condition based on the presence or absence of a peak in a predetermined frequency range that includes the specific frequency of the operating noise of the inverter 21 installed in the vehicle 20. Details of the determination of the road surface condition will be described later.

[0020] The in-vehicle communication unit 80 outputs sound data including information on the reflected sound of the sound generated in the vehicle 20, collected by the data collection unit 70, to the road surface condition determination device 10. The in-vehicle communication unit 80 may be configured by, for example, a wireless communication module, but is not limited to a specific device. In the present embodiment, the in-vehicle communication unit 80 is configured to be able to communicate with the road surface condition determination device 10 via the network 40.

[0021] Here, the data collection unit 70 may further include a temperature sensor in order to collect temperature data. The temperature data includes information on the temperature around the road surface. In this case, the in-vehicle communication unit 80 also outputs the temperature data to the road surface condition determination device 10.

[0022] Hereinafter, the details of the components of the road surface condition determination device 10 will be described. The communication unit 11 is configured to include one or more communication modules connected to the network 40. The communication unit 11 may include a communication module corresponding to a mobile communication standard such as 4G (4th Generation) or 5G (5th Generation). The communication unit 11 may include a communication module corresponding to a wireless LAN standard (for example, IEEE802.11). Further, the communication unit 11 may include a communication module corresponding to a wired LAN standard.

[0023] The storage unit 12 is one or more memories. The memory may be, for example, a semiconductor memory, a magnetic memory, an optical memory, etc., but is not limited thereto and can be any memory. The storage unit 12 is, for example, built in the road surface condition determination device 10, but can also be configured to be externally accessed by the road surface condition determination device 10 via an arbitrary interface.

[0024] The storage unit 12 stores various data used in various calculations performed by the control unit 13. The storage unit 12 may also store the results and intermediate data of various calculations performed by the control unit 13. In this embodiment, the storage unit 12 stores information on a specific frequency of the vehicle 20 and a predetermined frequency range including that specific frequency. Since the specific frequency can vary depending on the vehicle 20, it is preferable that it be identified based on the measurement of the operating sound of the inverter 21 or the like before the road surface condition is determined, and that this information is stored in the storage unit 12.

[0025] The control unit 13 is one or more processors. The processors are, for example, general-purpose processors or dedicated processors specialized for specific processing, but are not limited to these and can be any processor. The control unit 13 controls the overall operation of the road surface condition determination device 10.

[0026] Here, the road surface condition determination device 10 may have the following software configuration. One or more programs used to control the operation of the road surface condition determination device 10 are stored in the storage unit 12. When the programs stored in the storage unit 12 are read by the processor of the control unit 13, the control unit 13 is made to function as a data acquisition unit 131 and a determination unit 132.

[0027] The data acquisition unit 131 acquires sound data, including information on reflected sound generated in the vehicle 20, which is collected by the data collection unit 70 mounted on the vehicle 20. The data acquisition unit 131 may acquire temperature data. If the data collection unit 70 includes a temperature sensor, the data acquisition unit 131 may acquire temperature data collected by the data collection unit 70. If the data collection unit 70 does not include a temperature sensor, the data acquisition unit 131 may acquire temperature data included in weather information via the network 40. The data acquisition unit 131 may also acquire information from the storage unit 12 regarding a specific frequency of the vehicle 20 and a predetermined frequency range including that specific frequency. The data acquisition unit 131 outputs the acquired data and other information to the determination unit 132.

[0028] The determination unit 132 determines the condition of the road surface based on the presence or absence of peaks in a predetermined frequency range in the acquired sound data. The determination unit 132 may, for example, generate a frequency spectrum from the sound data as shown in Figure 3. The determination unit 132 extracts a predetermined frequency range from the frequency spectrum and determines the presence or absence of peaks at specific frequencies. Known methods may be used to determine the presence or absence of peaks, and is not limited to any particular method. The determination unit 132 may, for example, extract a maximum value for intensity and determine whether the frequency corresponding to the maximum value matches a specific frequency. Alternatively, the determination unit 132 may, for example, subtract the intensity of frequencies around (before and after) the extracted maximum value from the maximum value and determine that it is a peak (sharp change) if it is above a threshold. The determination unit 132 can determine that the condition of the road surface is Dry or Ice if there is a peak in the predetermined frequency range. The determination unit 132 can also determine that the condition of the road surface is Wet or Snow if there is no peak in the predetermined frequency range. For example, in the summer, the determination unit 132 may determine the road surface condition as dry if there is a peak in a predetermined frequency range, and wet if there is no peak.

[0029] The determination unit 132 may further determine the road surface condition based on temperature data. By using temperature data in combination, the determination unit 132 can estimate the road surface condition in even finer categories. Table 1 shows the method by which the determination unit 132 determines the road surface condition when using temperature data in combination. In Table 1, a temperature of "low" is indicated as, for example, 0°C or below, and all other temperatures are indicated as "normal".

[0030] [Table 1]

[0031] Thus, the predetermined frequency range includes a specific frequency of the operating sound of the inverter 21 equipped in the vehicle 20, and the presence or absence of a peak at that specific frequency is used for determination. Furthermore, as described above, the predetermined frequency range corresponds to a high-frequency range that is not significantly affected by noise such as driving noise. Therefore, in this embodiment, the road surface condition can be estimated with high accuracy by using a determination that utilizes a frequency range that includes a specific frequency that is less affected by noise during driving. In other words, the road surface condition determination device 10 according to this embodiment is suitable for estimating the road surface condition while the vehicle 20 is in motion.

[0032] Here, for example, the control unit 13 may warn the driver of the vehicle 20 to switch to manual driving if it determines that the road surface condition of the road on which the vehicle 20 is driving in automatic mode is Ice or Snow. In this way, the road surface condition determination device 10 may function as a control device that controls the vehicle 20 based on the determined road surface condition.

[0033] Figure 4 is a flowchart illustrating the process performed by the road surface condition determination device 10 to determine the road surface condition.

[0034] The road surface condition determination device 10 waits until the vehicle 20 is in motion (NO in step S1). When the vehicle 20 is in motion (YES in step S1), the road surface condition determination device 10 starts the process of determining the road surface condition. Here, as described above, the peak at a specific frequency (P1 in Figure 3) is largely due to the operating noise of the inverter 21 installed in the vehicle 20. The inverter 21 operates while the vehicle 20 is in motion, and the operating noise becomes louder. Therefore, when the vehicle 20 is in motion, it becomes possible to detect strong reflected sound at a specific frequency, and the road surface condition can be accurately estimated.

[0035] The road surface condition determination device 10 acquires sound data including information on reflected sound generated by the vehicle 20 (step S2). The road surface condition determination device 10 also acquires information of a specific frequency from the storage unit 12 (step S3). The road surface condition determination device 10 also acquires air temperature data including information on the temperature around the road surface on which the vehicle 20 is traveling (step S4).

[0036] As shown in Table 1, the road surface condition determination device 10 determines the road surface condition based on the presence or absence of peaks in a predetermined frequency range in the sound data and the temperature data (step S5).

[0037] The road surface condition determination device 10 controls the vehicle 20 based on the determined (estimated) road surface condition (step S6).

[0038] As described above, the road surface condition determination device 10 and control device according to this embodiment do not require, for example, a device for emitting ultrasonic waves, and can estimate the road surface condition with high accuracy with a simple configuration. Furthermore, the control device according to this embodiment can determine, for example, whether or not to continue autonomous driving based on the estimated road surface condition, and can control the vehicle 20 to drive safely.

[0039] While embodiments of this disclosure have been described based on the drawings and examples, it should be noted that those skilled in the art will find it easy to make various modifications or alterations based on this disclosure. Therefore, it should be noted that these modifications or alterations are included within the scope of this disclosure. For example, the functions included in each component or step can be rearranged in a logically consistent manner, and multiple components or steps can be combined into one or divided. Embodiments relating to this disclosure can also be realized as programs executed by a processor in the device and storage media recording such programs. These should also be understood to be included within the scope of this disclosure.

[0040] The configurations of the road surface condition determination device 10 and road surface condition determination system shown in Figures 1 and 2 are examples and are not limited to the configurations shown in Figures 1 and 2. For example, the road surface condition determination device 10 may be mounted on a vehicle 20. As shown in Figure 5, when the road surface condition determination device 10 is mounted on a vehicle 20, the road surface condition determination device 10 can acquire sound data and the like without going through the in-vehicle communication unit 80 and the network 40. The road surface condition determination device 10 may acquire sound data and the like from the data acquisition unit 70 using an in-vehicle network such as CAN (Controller Area Network).

[0041] Furthermore, the specific frequency is not limited to the frequency of the inverter 21's operating sound; it can be any sound emitted by the vehicle 20 that shows a peak in the high-frequency range. Therefore, even a vehicle 20 without an inverter 21 can be used to determine the road surface condition by setting the frequency of the sound showing that peak as the specific frequency, provided it has a peak in the high-frequency range that is less susceptible to noise such as driving noise. Contribution to the United Nations-led Sustainable Development Goals (SDGs)

[0042] The SDGs have been proposed to realize a sustainable society. One embodiment of this disclosure is considered to be a technology that can contribute to "No. 9 Industry, Innovation and Infrastructure" and other goals. [Explanation of Symbols]

[0043] 10. Road surface condition determination device 11 Communications Department 12 Storage section 13 Control Unit 20 vehicles 21 Inverter 30 tires 40 Networks 70 Data Acquisition Unit 80 In-vehicle communication unit 131 Data Acquisition Unit 132 Judgment section

Claims

1. A road surface condition determination device that determines the condition of the road surface on which a vehicle is traveling, A data acquisition unit that acquires sound data including information on reflected sound generated in the vehicle, collected by a data acquisition unit installed in the vehicle, The system includes a determination unit that determines the condition of the road surface based on the presence or absence of peaks in a predetermined frequency range in the acquired sound data, A road surface condition determination device in which the predetermined frequency range includes a specific frequency of the operating sound of the inverter installed in the vehicle.

2. The data acquisition unit acquires temperature data including information on the ambient temperature of the road surface. The road surface condition determination device according to claim 1, wherein the determination unit further determines the condition of the road surface based on the temperature data.

3. The road surface condition determination device according to claim 1 or 2, wherein the determination unit determines the condition of the road surface while the vehicle is in motion.

4. A control device mounted on a vehicle and used to control the vehicle, A data acquisition unit that acquires sound data including information on reflected sound generated in the vehicle, collected by a data acquisition unit installed in the vehicle, The system includes a determination unit that determines the condition of the road surface on which the vehicle is traveling based on the presence or absence of peaks in a predetermined frequency range in the acquired sound data, The predetermined frequency range includes a specific frequency of the operating sound of the inverter installed in the vehicle. A control device that controls the vehicle based on the determined road surface conditions.

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