Obstacle detection system and obstacle detection method

Abstract

To provide an obstacle detection system that can accurately detect an obstacle on the road surface.SOLUTION: An obstacle detection system comprises: a light projection unit that projects pattern light PL from a vehicle B toward the road surface T in the front; an imaging unit that picks up an image of the road surface T on which the pattern light PL is projected; and a detection unit that detects the presence or absence of an obstacle H from the image picked up by the imaging unit. The light projection unit projects the pattern light PL that forms a linear pattern LP inclined at a predetermined angle. When the linear pattern LP is projected on the obstacle H, the linear pattern LP is bent, and thereby the detection unit detects the obstacle H on the road surface T.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an obstacle detection system and an obstacle detection method. [Background technology]

[0002] Conventionally, vehicle lighting fixtures mounted on vehicles emit, as illumination light, a passing beam (low beam) that forms a low beam light distribution pattern including a cutoff line at the upper end, and a driving beam (high beam) that forms a high beam light distribution pattern above the low beam light distribution pattern, toward the front of the vehicle.

[0003] Meanwhile, in the field of vehicle lighting, in order to improve driving safety, an obstacle detection system has been proposed that projects a pattern of light ahead of the vehicle in addition to the above-mentioned illumination light, and detects obstacles on the road surface while capturing an image of the road surface onto which this pattern of light is projected (see, for example, Patent Document 1 below). Such obstacle detection systems are expected to be applied to autonomous driving systems and advanced driver assistance systems.

[0004] Specifically, Patent Document 1 listed below discloses a road surface judgment device for a vehicle, which includes an irradiation device that irradiates a pattern light onto a road surface on which a vehicle is traveling or onto the surroundings of the vehicle, a detection device that detects the pattern light irradiated onto the road surface, and a judgment unit that judges the condition of the road surface based on the detected pattern light, wherein the irradiation device is capable of irradiating the pattern light intermittently for a short period of time so that a period during which the pattern light is not irradiated is longer than a period during which the pattern light is irradiated, and when it is necessary to irradiate the pattern light, if the irradiation device is already turned on, the device irradiates the pattern light so that grid lines are drawn as shadows within the irradiation range, and if the irradiation device is turned off, the device irradiates the pattern light so that the grid lines are drawn with light. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6637936 Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, the invention described in the above-mentioned Patent Document 1 projects patterned light so as to draw grid lines with light, making it easier for the driver to visually recognize unevenness in the road surface and changes in road shape due to landslides or snow accumulation as curvatures in straight lines.

[0007] On the other hand, when detecting the presence or absence of obstacles on the road surface by projecting such a grid-shaped pattern light and capturing an image of the road surface onto which the pattern light is projected, changes in the shape of the pattern light are detected as differences in the captured image, and the presence or absence of an obstacle is determined from the magnitude of the difference.

[0008] However, when detecting such changes in the shape of pattern light as differences, there is a risk that bright areas, such as street lights, may be mistakenly detected as obstacles due to the difference in brightness, making it difficult to accurately detect obstacles on the road surface.

[0009] The present invention has been proposed in view of the above-described conventional circumstances, and aims to provide an obstacle detection system and an obstacle detection method that are capable of detecting obstacles on the road surface with high accuracy. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides the following means. [1] A light projection unit that projects patterned light from the vehicle toward a road surface ahead; an imaging unit that images a road surface onto which the pattern light is projected; a detection unit that detects the presence or absence of an obstacle from the image captured by the imaging unit, the light projecting unit projects pattern light that forms a linear pattern inclined at a predetermined angle; An obstacle detection system characterized in that the detection unit detects an obstacle on a road surface by the linear pattern bending when the linear pattern is projected onto an obstacle. [2] The obstacle detection system described in [1], wherein the linear pattern satisfies 0°<θ≦60° when the angle of inclination of the linear pattern with respect to a vertical line passing through the projection center of the pattern light is θ. [3] The obstacle detection system described in [2], wherein the detection unit determines that an obstacle on the road surface has been detected when 0.1≦|β-α| / α is satisfied, where α is the slope of the linear pattern before bending and β is the slope of the linear pattern after bending. [4] The obstacle detection system described in [1], wherein the imaging unit is located on the opposite side of the vehicle width direction from the side on which the linear pattern is inclined relative to the light projecting unit. [5] The obstacle detection system according to [1], wherein the light projecting unit projects pattern light that forms a striped pattern in which the linear patterns are arranged in parallel. [6] The obstacle detection system according to [5], characterized in that the striped pattern satisfies 2≦b / a, where a is the width of the linear pattern and b is the width between the linear patterns. [7] The obstacle detection system according to [1], wherein the patterned light is infrared light. [8] A pattern light is projected from the vehicle onto the road surface ahead, forming a linear pattern inclined at a predetermined angle; An obstacle detection method, characterized in that when the linear pattern is projected onto an obstacle, the linear pattern is bent, thereby detecting the obstacle on the road surface. [Effects of the Invention]

[0011] As described above, the present invention provides an obstacle detection system and an obstacle detection method that enable accurate detection of obstacles on the road surface. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram showing a state in which a patterned light is projected from a vehicle onto a road surface ahead and an obstacle on the road surface is detected in an obstacle detection system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a block diagram showing a configuration of an obstacle detection system. [Figure 3] FIG. 2 is a schematic diagram showing the configuration of a light projecting unit. [Figure 4] 10 is a schematic diagram showing a stripe pattern when pattern light is projected onto a virtual vertical screen. FIG. [Figure 5] FIG. 5 is an enlarged schematic diagram of a striped pattern of a boxed area A in FIG. [Figure 6] 10 is a perspective view showing a state in which patterned light is projected from a light projecting unit toward a road surface ahead. FIG. [Figure 7] 10 is a side view showing a state in which patterned light is projected from a light projecting unit toward a road surface ahead. FIG. [Figure 8] 10 is a plan view showing a state in which patterned light is projected from a light projecting unit toward a road surface ahead. FIG. [Figure 9] 1A and 1B are schematic diagrams showing the arrangement of the imaging unit relative to the light projecting unit, in which FIG. 1A is a diagram showing the case where the linear pattern is inclined to the right, and FIG. 1B is a diagram showing the case where the linear pattern is inclined to the left. [Figure 10] 10 is a flowchart showing a procedure for detecting the presence or absence of an obstacle from image data supplied from an imaging unit. [Figure 11] 10A and 10B are schematic diagrams showing changes in the inclination of a linear pattern before and after bending. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, the dimensions of the components may be shown at different scales to make them easier to see, and the dimensional ratios of the components may not necessarily be the same as in reality.

[0014] As one embodiment of the present invention, an obstacle detection system 1 shown in, for example, FIGS. 1 to 11 will be described. FIG. 1 is a schematic diagram showing a state in which pattern light PL is projected from a vehicle B toward a road surface T ahead in an obstacle detection system 1, and an obstacle H on the road surface T is detected. FIG. 2 is a block diagram showing the configuration of the obstacle detection system 1. FIG. 3 is a schematic diagram showing the configuration of a light projecting unit 2. FIG. 4 is a schematic diagram showing a stripe pattern SP when pattern light PL is projected onto a virtual vertical screen S. FIG. 5 is a schematic diagram of the stripe pattern SP, with an enlarged view of a boxed area A in FIG. 4. FIG. 6 is a perspective view showing a state in which pattern light PL is projected from the light projecting unit 2 toward the road surface T ahead. FIG. 7 is a side view showing a state in which pattern light PL is projected from the light projecting unit 2 toward the road surface T ahead. FIG. 8 is a plan view showing a state in which pattern light PL is projected from the light projecting unit 2 toward the road surface T ahead. Fig. 9 shows the arrangement of the imaging unit 3 relative to the light projecting unit 2, with (A) being a schematic diagram showing a case where the linear pattern LP is tilted to the right and (B) being a schematic diagram showing a case where the linear pattern LP is tilted to the left. Fig. 10 is a flowchart showing a procedure for detecting the presence or absence of an obstacle H from image data supplied from the imaging unit 3. Fig. 11 is a schematic diagram showing a change in the tilt of the linear pattern LP before and after bending.

[0015] In addition, in the drawings shown below, an XYZ Cartesian coordinate system is set up, with the X-axis direction representing the fore-and-aft direction (length direction) of vehicle B, the Y-axis direction representing the left-and-right direction (width direction) of vehicle B, and the Z-axis direction representing the up-and-down direction (height direction) of vehicle B.

[0016] The obstacle detection system 1 of this embodiment implements an obstacle detection method in which, as shown in Figure 1, a pattern light PL that forms a linear pattern LP (striped pattern SP) inclined at a predetermined angle is projected from a vehicle B toward a road surface T ahead, and when the linear pattern LP is projected onto an obstacle H, the linear pattern LP bends, thereby detecting an obstacle H on the road surface T.

[0017] Specifically, as shown in Figure 2, this obstacle detection system 1 includes a light-projecting unit 2 that projects pattern light PL from the vehicle B toward the road surface T ahead, an imaging unit 3 that images the road surface T onto which the pattern light PL is projected, and a detection unit 4 that detects the presence or absence of an obstacle H from the image captured by the imaging unit 3.

[0018] As shown in FIG. 3, the light-projecting unit 2 is a light-projecting device (projector) having a light source 5, a pattern-forming element 6, and a projection lens 7. The light L emitted from the light source 5 is converted into pattern light PL by the pattern-forming element 6, and then this pattern light PL is magnified and projected forward of the vehicle B by the projection lens 7.

[0019] The light source 5 may be, for example, one that emits visible light such as white light that is visible to the driver of the vehicle B, or one that emits invisible light such as infrared (IR) light that is not visible to the driver. The light source 5 may be, for example, a light-emitting element such as a light-emitting diode (LED) or a laser diode (LD).

[0020] The pattern forming element 6 may be any element capable of converting the light L emitted from the light source 5 into pattern light PL, and may be, for example, a diffraction grating such as a computer generated hologram (CGH), or an optical modulation element such as a liquid crystal element or a MEMS mirror.

[0021] The projection lens 7 may be a convex lens that enlarges and projects the pattern light PL forward of the vehicle B. The projection lens 7 may also be disposed between the light source 5 and the pattern forming element 6.

[0022] In this embodiment, the patterned light PL forms a striped pattern SP in which a plurality of linear patterns LP inclined rightward are arranged in parallel.

[0023] FIG. 4 shows a striped pattern SP formed on the surface of the virtual vertical screen S when pattern light PL is projected onto the virtual vertical screen S facing the light projecting unit 2 in a simulation.

[0024] As shown in Figure 4, the striped pattern SP is formed by a plurality of linear patterns LP that extend in a direction intersecting a vertical line VL passing through the projection center O of the pattern light PL and are arranged at equal intervals in a direction parallel to a horizontal line HL that is perpendicular to this vertical line VL at the projection center O.

[0025] When the angle of inclination of the linear pattern LP with respect to the vertical line VL is θ, it is preferable that the linear pattern LP satisfies 0°<θ≦60°, more preferably 35≦θ≦55° (θ=45°±10°), and most preferably θ=45°.

[0026] 5, the stripe pattern SP preferably satisfies 2≦b / a, where a is the width of the light linear pattern LP and b is the width between the dark linear patterns LP. That is, the stripe pattern SP is preferably set so that the ratio of the light width a to the dark width b is 1:2 or greater.

[0027] When the light-projecting unit 2 projects patterned light PL toward the road surface T ahead, as shown in Figures 6, 7 and 8, a dashed linear pattern LP (striped pattern SP) that partially overlaps with the road surface T is projected as a solid linear pattern LP (striped pattern SP) onto the road surface T between the virtual vertical screen S1 in front that contacts the road surface T and the virtual vertical screen S2 in the back that partially overlaps with the road surface T.

[0028] The imaging unit 3 is an imaging device (camera) that uses a solid-state imaging element such as a CCD or CMOS image sensor, and captures an image of the road surface T onto which the above-mentioned pattern light PL is projected, and supplies the captured image data to the detection unit 4.

[0029] 9(A) and 9(B), it is preferable that the imaging unit 3 be located on the opposite side of the vehicle B in the width direction from the side where the linear pattern LP is inclined relative to the light projector 2. That is, as shown in FIG. 9(A), when the linear pattern LP of the patterned light PL is inclined to the right, it is preferable to arrange the imaging unit 3 on the right side relative to the light projector 2. On the other hand, as shown in FIG. 9(B), when the linear pattern LP of the patterned light PL is inclined to the left, it is preferable to arrange the imaging unit 3 on the left side relative to the light projector 2.

[0030] When the above-mentioned inclined linear pattern LP is projected onto an obstacle H, the linear pattern LP bends, and this is used to detect the obstacle H on the road surface T. In this case, the appearance of the bent linear pattern LP differs depending on the inclination direction of the linear pattern LP and the positional relationship of the imaging unit 3 with respect to the light projecting unit 2.

[0031] In this case, by arranging the imaging unit 3 on the opposite side of the vehicle B in the width direction from the side where the linear pattern LP is inclined relative to the light projecting unit 2, it is possible to make the curved linear pattern LP easier to see.

[0032] This makes it possible to make it easier for the imaging unit 3 to detect that the inclined linear pattern LP is bent when the inclined linear pattern LP is projected onto the obstacle H.

[0033] The detection unit 4 is a control device (computer) such as an ECU (Electronic Control Unit), and performs calculation processing to detect the presence or absence of an obstacle H from the image data supplied from the imaging unit 3, according to the flowchart shown in FIG.

[0034] Specifically, in the detection unit 4, first, in step S101 shown in FIG.

[0035] Next, in step S102 shown in Fig. 10, the bending position of the linear pattern LP is detected from the image data. Then, if the bending position of the linear pattern LP is detected, the process proceeds to step S103 shown in Fig. 10.

[0036] Next, in step S103 shown in FIG. 10, the presence or absence of an obstacle H on the road surface T is determined based on the bending state of the linear pattern LP.

[0037] Specifically, at a bending position of the linear pattern LP, when the slope of the linear pattern LP before bending is α and the slope of the linear pattern LP after bending is β, if 0.1≦|β-α| / α is satisfied, it is determined that an obstacle H on the road surface T has been detected (obstacle H is present). In other words, if the slope β after bending changes by ±10% or more from the slope α of the linear pattern LP before bending, it is determined that an obstacle H has been detected (obstacle present). In this embodiment, for example, as shown in FIG. 11 , the slope α of the linear pattern LP before bending is at an angle θ1 with respect to the vertical line VL, and the slope β of the linear pattern LP after bending is at an angle θ2 with respect to the vertical line VL.

[0038] Next, if it is determined that an obstacle H has been detected (obstacle present), the process proceeds to step S104 shown in Fig. 10. Then, in this step S104, a notification (warning) is given to the driver of vehicle B that an obstacle H on the road surface T has been detected.

[0039] Specific notification means may include, for example, notifying the driver of the situation with an alarm sound or displaying a warning on the meter panel of vehicle B. In addition, vehicle B may be configured to automatically brake or steer in order to avoid contact with obstacle H.

[0040] On the other hand, in step S103 shown in Fig. 10, if 0.1≦|β-α| / α is not satisfied, that is, if the change in the slope β after bending is within ±10% of the slope α of the linear pattern LP before bending, it is determined that no obstacle H has been detected on the road surface T (no obstacle). In this case, the process returns to step S101 shown in Fig. 10 and the above-mentioned calculations are repeated.

[0041] As described above, in the obstacle detection system 1 of this embodiment, when the above-mentioned inclined linear pattern LP is projected onto the obstacle H, the linear pattern LP bends, making it possible to accurately detect the obstacle H on the road surface T.

[0042] In particular, the obstacle detection system 1 of this embodiment can be suitably used when detecting a low obstacle H, such as a person lying on the road surface T, for example.

[0043] Furthermore, in the obstacle detection system 1 of this embodiment, by detecting the presence or absence of an obstacle H from the change in inclination caused by the bending of the linear pattern LP described above, it is possible to prevent erroneous detection of an obstacle H compared to conventional methods in which the change in shape of the pattern light PL is detected as a difference and the presence or absence of an obstacle H is determined from the magnitude of that difference.

[0044] Furthermore, the obstacle detection system 1 of this embodiment does not need to form a complex pattern light PL, and can accurately detect an obstacle H with a simple configuration.

[0045] The present invention is not necessarily limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0046] For example, the linear pattern LP is not limited to visible light such as the above-mentioned white light, and may be invisible light such as IR light. When invisible light is projected, the imaging unit 3 can capture an image without the driver being able to see the linear pattern LP (striped pattern SP), and it is possible to project the pattern light PL so as not to obstruct the driver's field of vision.

[0047] In the above embodiment, an example is given of detecting the presence or absence of an obstacle H from the change in inclination caused by the bending of the linear pattern LP described above. However, it is also possible to determine an approximation equation of the linear pattern LP from image data captured by the imaging unit 3, and detect the presence or absence of an obstacle H from the change in the approximation equation when the linear pattern LP is bent by projecting light onto the obstacle H.

[0048] Furthermore, the obstacle detection method to which the present invention is applied is not limited to being implemented using the above-mentioned obstacle detection system 1, but can also be applied to cases where, for example, a visible light pattern light PL that forms the above-mentioned linear pattern LP (striped pattern SP) is projected from the light-projecting unit 2 from vehicle B toward the road surface T ahead, and when this linear pattern LP is projected onto obstacle H, the driver of vehicle B is made to visually recognize that the linear pattern LP has bent, thereby detecting obstacle H on the road surface T. [Explanation of symbols]

[0049] 1... Obstacle detection system 2... Light projecting unit 3... Imaging unit 4... Detection unit 5... Light source 6... Pattern forming element 7... Light projecting lens LP... Linear pattern SP... Striped pattern PL... Pattern light B... Vehicle T... Road surface H... Obstacle

Claims

1. a light projection unit that projects patterned light from the vehicle toward a road surface ahead; an imaging unit that images a road surface onto which the pattern light is projected; a detection unit that detects the presence or absence of an obstacle from the image captured by the imaging unit, the light projecting unit projects pattern light that forms a linear pattern inclined at a predetermined angle; An obstacle detection system characterized in that the detection unit detects an obstacle on a road surface by the linear pattern bending when the linear pattern is projected onto an obstacle.

2. 2. The obstacle detection system according to claim 1, wherein the linear pattern satisfies 0°<θ≦60°, where θ is an angle of inclination of the linear pattern with respect to a vertical line passing through the center of projection of the pattern light.

3. The obstacle detection system according to claim 2, characterized in that the detection unit determines that an obstacle on the road surface has been detected if 0.1≦|β−α| / α is satisfied, where α is the slope of the linear pattern before bending and β is the slope of the linear pattern after bending.

4. 2. The obstacle detection system according to claim 1, wherein the imaging unit is located on the opposite side of the light projecting unit from the side on which the linear pattern is inclined in the width direction of the vehicle.

5. 2. The obstacle detection system according to claim 1, wherein the light projecting unit projects patterned light that forms a striped pattern in which the linear patterns are arranged in parallel.

6. 6. The obstacle detection system according to claim 5, wherein the striped pattern satisfies 2≦b / a, where a is the width of the linear pattern and b is the width between the linear patterns.

7. 2. The obstacle detection system according to claim 1, wherein the patterned light is infrared light.

8. A pattern light is projected from the vehicle onto the road surface ahead, forming a linear pattern inclined at a predetermined angle, An obstacle detection method, characterized in that when the linear pattern is projected onto an obstacle, the linear pattern is bent, thereby detecting the obstacle on the road surface.

Images