Road surface determination device

Abstract

To provide a road-surface determination apparatus capable of determining the state of a road surface while costing less.SOLUTION: A road-surface determination apparatus 1 is incorporated in a vehicle 100 enabled for an automatic operation. The road-surface determination apparatus 1 includes: a lighting device 11 for illuminating externally to the vehicle 100 toward a road surface traveled by the vehicle 100 with a lamp indicating that the vehicle 100 is engaged in an automatic operation; an optical receiver 12 for receiving reflecting light of the lamp from the road surface; a calculation part 14 for calculating a reflectance ratio of the road surface to the lamp on the basis of optical intensity of the lamp and that of the reflecting light received by the optical receiver 12; and a determination part 15 for determining a state of the road surface on the basis of the aforementioned reflectance ratio.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a road surface judgment device. [Background technology]

[0002] There is known a technology for determining the condition of the road surface on which a vehicle is traveling. Patent Document 1 describes a road surface condition determination processing method for determining the road surface condition ahead of a vehicle from an image captured by a camera carried by the vehicle. Specifically, this road surface condition determination processing method determines the conditions of snow, water, and ice on the road surface using an ultraviolet image, an infrared image, and a temperature distribution image captured by the camera. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019-111366 Summary of the Invention [Problem to be solved by the invention]

[0004] The road surface condition determination process described in Patent Document 1 determines the road surface condition using multiple types of captured images, which makes the determination process complicated and may increase the cost of the process.

[0005] An object of the present disclosure is to provide a road surface judgment device that can judge the condition of a road surface while reducing costs. [Means for solving the problem]

[0006] The road surface judgment device disclosed herein is a road surface judgment device mounted on a vehicle capable of autonomous driving, and includes a lighting device that shines a light toward the outside of the vehicle indicating that the vehicle is in autonomous driving, onto the road surface on which the vehicle is traveling, a light receiving unit that receives the light reflected from the road surface, a calculation unit that calculates the reflectivity of the road surface relative to the light based on the light intensity of the light and the light intensity of the reflected light received by the light receiving unit, and a judgment unit that judges the condition of the road surface based on the reflectivity.

[0007] In this road surface judgment device, the reflectivity of the road surface relative to the lamp is calculated based on the light intensity of the lamp directed toward the outside of the vehicle indicating that the vehicle is in autonomous driving and the light intensity of the light reflected from the road surface received by the light receiving unit, and the road surface condition is judged based on this reflectivity. This makes it possible to judge the condition of the road surface on which the vehicle is traveling without performing complex processing such as image processing. Furthermore, because the lamp indicating that the vehicle is in autonomous driving is used to judge the road surface condition, a separate light source is not required. Therefore, this road surface judgment device can judge the road surface condition while reducing costs.

[0008] In the road surface judgment device of the present disclosure, the lighting equipment and the light receiving unit may be located at the front lower part of the vehicle. In this case, the optical path length can be shortened compared to when the lighting equipment and the light receiving unit are located at the top of the vehicle, and therefore, when the light receiving unit receives light reflected from the road surface, it can be made less susceptible to the influence (disturbance) of light other than the light from the lighting equipment (ambient light) and scattering by substances in the air.

[0009] The road surface judgment device of the present disclosure may include a filter that is provided on the optical path of the reflected light toward the light receiving unit and that transmits only light in the frequency band of the lamp. In this case, the light receiving unit can be less susceptible to the influence of ambient light when receiving the reflected light from the road surface. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a road surface judgment device that can judge the state of a road surface while reducing costs. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing a road surface judgment device according to this embodiment. [Figure 2] FIG. 2 is a block diagram showing the functional configuration of the road surface judgment device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and overlapping parts are omitted.

[0013] FIG. 1 is a schematic diagram showing a vehicle 100 equipped with a road surface judgment device 1 according to this embodiment. FIG. 2 is a block diagram showing the functional configuration of the road surface judgment device 1 shown in FIG. 1. The vehicle 100 shown in FIGS. 1 and 2 is a vehicle 100 capable of autonomous driving. The vehicle 100 may have an occupant on board, or may be unmanned. The vehicle 100 may be, for example, a large vehicle, a medium-sized vehicle, a standard passenger car, a small vehicle, or a light vehicle, and one example is an industrial vehicle such as a truck. As shown in FIG. 1, the vehicle 100 is traveling on a road surface S of a road H.

[0014] The vehicle 100 is equipped with a lighting device 11, a photoreceiver (light receiving unit) 12, a filter 13, and a control device 2. The lighting device 11 emits a light L toward the road surface S, which is directed to the outside of the vehicle 100 and indicates that the vehicle 100 is in autonomous driving. The color of the light L is, for example, blue-green (turquoise blue). The lighting device 11 is disposed, for example, at the front lower part of the vehicle 100, and emits the light L toward the front of the vehicle 100.

[0015] The light receiver 12 receives reflected light R, which is a portion of the light from the lamp L that is reflected by the road surface S. The light receiver 12 is disposed, for example, at the front lower part of the vehicle 100, and receives the reflected light R that is reflected in front of the vehicle 100. The light receiver 12 outputs a signal indicating the light intensity of the received reflected light R to a calculation unit 14, which will be described later.

[0016] The filter 13 is provided on the optical path of the reflected light R directed toward the receiver 12, and transmits only the frequency band of the light L. The filter 13 is disposed, for example, on the light receiving surface of the receiver 12 onto which the reflected light R is incident. Note that the filter 13 is not shown in FIG. 2.

[0017] The control device 2 is an electronic control unit (ECU) that performs various controls related to the vehicle 100. The control device 2 is mounted on the vehicle 100. The control device 2 is composed of a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), etc. The control device 2 loads a program stored in the ROM into the RAM and executes it on the CPU, thereby controlling the vehicle 100. The control device 2 may be composed of multiple electronic control units or may be composed of a single electronic control unit.

[0018] The control device 2 determines the state of the road surface S and performs automatic driving control of the vehicle 100 according to the determination result. As an example, the control device 2 controls the speed, acceleration, etc. of the vehicle 100 based on the determination result. The control device 2 has, as functional components, a calculation unit 14, a determination unit 15, a control unit 16, and a communication unit 17.

[0019] The calculation unit 14 is a functional unit that calculates the reflectance of the road surface S with respect to the light L based on the light intensity of the light L and the light intensity of the reflected light R received by the light receiver 12. The light intensity of the light L may be obtained, for example, by detecting and measuring the light L emitted from the lighting device 11 using a separately provided measuring device, or may be obtained based on the specifications of the lighting device 11 if the specifications are known in advance. The calculation unit 14 also obtains the light intensity of the reflected light R by receiving the output signal from the light receiver 12. The light intensity of the light L and the light intensity of the reflected light R are, for example, illuminance. The calculation unit 14 then calculates the reflectance of the road surface S using the light intensity of the light L and the light intensity of the reflected light R. Any method may be used to calculate the reflectance of the road surface S. The calculation unit 14 transmits the calculated reflectance to the determination unit 15.

[0020] The determination unit 15 is a functional unit that determines the state of the road surface S based on the reflectance calculated by the calculation unit 14. The state of the road surface S determined by the determination unit 15 is a state related to the magnitude of the friction coefficient of the road surface S. That is, the determination unit 15 determines one road surface state from among road surface states of the road surface S related to various friction coefficients, such as a dry state with a high friction coefficient, a wet state with a medium friction coefficient, a snowy state with a low friction coefficient, and an icy state with a lower friction coefficient.

[0021] In general, it is considered that as the friction of the road surface S decreases, the road surface becomes smoother and the reflectance of the road surface S increases. Therefore, the determination unit 15 acquires the reflectance of the road surface S from the calculation unit 14 and compares the reflectance with one or more preset threshold values, thereby being able to determine the state of the road surface S.

[0022] As a mode of determination by the determination unit 15, for example, a mode of determining whether or not the state of the road surface S is a low μ road state (a mode of determination using two values) is conceivable. A low μ road state is, for example, a state corresponding to a snowy state and an icy state among the above road surface states. In this case, since it is considered that the reflectance of a snowy road surface S is lower than the reflectance of a frozen road surface S, the determination unit 15 uses a predetermined reference value of the reflectance of the snowy road surface S as a threshold value, compares the threshold value with the reflectance calculated by the calculation unit 14, and can determine that the state of the road surface S is a low μ road state when the reflectance calculated by the calculation unit 14 is higher than the threshold value.

[0023] Another possible mode of determination by the determination unit 15 is, for example, determining which of a plurality of road surface conditions the road surface S is in. In this case, for example, a plurality of reflectance thresholds corresponding to the respective road surface conditions are set in advance, and the determination unit 15 can determine which road surface condition the road surface S is in by comparing the reflectance calculated by the calculation unit 14 with the plurality of thresholds. As an example, the determination unit 15 can determine that the road surface S is in a wet state when the reflectance calculated by the calculation unit 14 is between a threshold corresponding to the reflectance in a wet state among the plurality of road surface conditions and another threshold corresponding to the reflectance in a snow-covered state among the plurality of road surface conditions. The same applies to other road surface conditions.

[0024] The determination unit 15 transmits determination result information indicating the determination result to the control unit 16 and the communication unit 17. The determination result information may include the reflectance of the road surface S.

[0025] The control unit 16 is a functional unit that performs control related to the autonomous driving of the vehicle 100. When the control unit 16 receives determination result information from the determination unit 15, the control unit 16 controls the driving of the vehicle 100 based on the determination result information. For example, when the determination result information indicates that the state of the road surface S is a low μ road state, the control unit 16 controls the vehicle 100 so that the vehicle 100 can drive safely in accordance with the state of the road surface S. Examples of control by the control unit 16 include controlling the speed of the vehicle 100 so as to increase the distance between the vehicle 100 and another vehicle traveling in front of the vehicle 100, limiting at least one of the acceleration, jerk (jerk), and speed of change of the steering angle of the vehicle 100, and changing the driving mode of the vehicle 100 to a snowy road driving mode.

[0026] The communication unit 17 is a functional unit that controls wireless communication between the vehicle 100 and the outside. The communication unit 17 performs wireless communication with another vehicle 200 traveling on the road H, thereby enabling transmission and reception of various information between the vehicle 100 and the other vehicle 200. For example, when the communication unit 17 receives determination result information from the determination unit 15, it transmits the determination result information to the other vehicle 200. This enables information sharing with the outside of the vehicle 100 regarding the state of the road surface S, and the other vehicle 200 that receives the determination result information can travel safely in accordance with the state of the road surface S indicated by the determination result, even if it does not have a road surface determination function.

[0027] Of the above-mentioned components, the lighting equipment 11, the light receiver 12, the filter 13, the calculation unit 14, and the determination unit 15 constitute the road surface determination device 1. The road surface determination device 1 is a device that determines the state of the road surface S, and is mounted on the vehicle 100. As described above, in the road surface determination device 1, the lighting equipment 11, the light receiver 12, the filter 13, the calculation unit 14, and the determination unit 15 function to determine the state of the road surface based on the reflectivity of the road surface S with respect to the light L. As described above, the determination result information determined by the road surface determination device 1 is used for controlling the vehicle 100 by the control unit 16, and for sharing information with other vehicles 200, etc.

[0028] As described above, in the road surface judgment device 1, the reflectance of the road surface S with respect to the light L is calculated based on the light intensity of the light L that is directed toward the outside of the vehicle 100 and indicates that the vehicle 100 is in autonomous driving, and the light intensity of the reflected light R of the light L from the road surface S that is received by the light receiver 12, and the state of the road surface S is judged based on this reflectance. This makes it possible to judge the state of the road surface S on which the vehicle 100 is traveling without performing complex processing such as image processing. Furthermore, when judging the state of the road surface S, the light device 11 that indicates that the vehicle is in autonomous driving is used, so a separate light source is not required. Therefore, with this road surface judgment device 1, the state of the road surface S can be judged while reducing costs.

[0029] Conventionally, drivers visually judge the road surface condition, such as whether the road surface on which their vehicle is traveling is a low μ road, such as icy road. However, when their vehicle is in an autonomous driving mode (particularly, an unmanned autonomous driving mode), there is a demand for automating the determination of the road surface condition. The road surface determination device 1 makes it possible to automate the determination of the road surface condition by calculating the reflectance of the road surface S using lighting devices 11 that indicate that the vehicle is in autonomous driving mode.

[0030] Furthermore, the road surface judgment device 1 calculates the reflectance using a light source that is the light L, and therefore can calculate the reflectance of the road surface S even in rainy weather. Furthermore, the road surface judgment device 1 uses the light L that is always turned on to notify the outside that the vehicle is in autonomous driving mode, even during the daytime when there is a possibility that the headlights will not be turned on, and therefore can stably calculate the reflectance of the road surface S regardless of the time of day, etc. Furthermore, the road surface judgment device 1 does not require information provided by other vehicles, and can judge the condition of the road surface S only by the vehicle 100.

[0031] In this embodiment, the lighting device 11 and the light receiver 12 are disposed at the front lower portion of the vehicle 100. In this case, when the light receiver 12 receives the reflected light R from the road surface S, it can be made less susceptible to the influence (disturbance) of light other than the light from the lamp (ambient light) and scattering by substances in the air.

[0032] The road surface judgment device 1 of the present disclosure has a filter 13 that is provided on the optical path of the reflected light R heading toward the light receiver 12 and transmits only light in the frequency band of the lamp L. In this case, when the light receiver 12 receives the reflected light R from the road surface S, it can be made less susceptible to the influence of ambient light.

[0033] The above embodiment has described one aspect of the present disclosure. Therefore, the present disclosure is not limited to the above example and may be modified as desired.

[0034] For example, the road surface judgment device 1 may further include a control unit 16. That is, after judging the reflectance of the road surface S, the road surface judgment device 1 may control the vehicle 100 based on the judgment result. The road surface judgment device 1 may further include a communication unit 17. That is, after judging the reflectance of the road surface S, the road surface judgment device 1 may transmit at least one of the reflectance of the road surface S and the judgment result to another vehicle 200 by vehicle-to-vehicle communication. This makes it possible to share information indicating the slipperiness of the road surface S with another vehicle 200 traveling on the road H. The road surface judgment device 1 may further include both the control unit 16 and the communication unit 17.

[0035] The lighting device 11 and the light receiver 12 do not have to be arranged at the front lower part of the vehicle 100, and may be arranged, for example, on the side of the vehicle 100. Furthermore, the road surface judgment device 1 does not have to have the filter 13. Furthermore, judgment result information on the state of the road surface S judged by the judgment unit 15 does not have to be transmitted to the outside of the vehicle 100. [Explanation of symbols]

[0036] 1...road surface determination device, 11...lighting device, 12...light receiver (light receiving unit), 13...filter, 14...calculation unit, 15...determination unit, 100...vehicle, L...light, R...reflected light, S...road surface

Claims

1. A road surface judgment device mounted on an autonomously driven vehicle, a lighting device that emits a light toward the outside of the vehicle, indicating that the vehicle is in autonomous driving, toward a road surface on which the vehicle is traveling; a light receiving unit that receives reflected light of the lamp from the road surface; a calculation unit that calculates a reflectance of the road surface with respect to the lamp based on the light intensity of the lamp and the light intensity of the reflected light received by the light receiving unit; a determination unit that determines the state of the road surface based on the reflectance; Equipped with Road surface determination device.

2. The lighting device and the light receiving unit are arranged in a front lower portion of the vehicle. The road surface judgment device according to claim 1 .

3. A filter is provided on the optical path of the reflected light toward the light receiving unit, and transmits only light in the frequency band of the lamp. The road surface judgment device according to claim 1 or 2.

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