JP2013024636A - Distance measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance measuring apparatus capable of measuring a distance highly accurately, even when a relative positional relationship between a moving body and an object changes.SOLUTION: A distance measuring apparatus performs measurement by: emitting, from a light projection part 11, a first light projection pulse having a light-emitting region that has an upper end and that spreads out in the horizontal direction; capturing an image of region light reflected at a measuring object 31 by a camera 12; performing synchronous detection processing on the image to detect an upper end edge corresponding to the upper end of the first light projection pulse; detecting the shape edge of the measuring object 31 from an image of the measuring object 31 captured while the first light projection pulse is being turned off; and, when the shape edge and the upper end edge match with each other, removing the upper end edge, and measuring a distance to the measuring object 31 by a principle of triangulation using the upper end edge in the case where both the edges match with each other.

Description

  The present invention relates to a distance measuring device that is provided in a moving body such as a vehicle and measures a distance to an object existing around the moving body.

  As a distance measuring device for measuring a distance to an object existing around a moving body such as a vehicle, for example, a device described in Japanese Patent Application Laid-Open No. 2008-157718 (Patent Document 1) is known. In this patent document 1, it has a pair of light emitting element and light receiving element which have base line length, and detects the distance and direction to a measuring object by a triangulation method. In addition, the sheet beam collected by the toroidal lens is pulse-emitted multiple times, the light receiving position is extracted from the light receiving element in synchronization with the light emission timing, the irradiation direction of the sheet beam and the incident direction of the reflected light to the light receiving element, The distance to the object is measured based on the base line length of the light emitting element and the light receiving element.

JP 2008-157718 A

  However, in the conventional example disclosed in Patent Document 1 described above, when the relative positional relationship between the moving object and the object fluctuates, a reflected signal from the object cannot be detected when pulsed light is irradiated. There is an error in position information used for triangulation, and there is a possibility that accurate distance measurement cannot be performed.

  The present invention has been made to solve such a conventional problem, and the object of the present invention is to achieve high accuracy even when the relative positional relationship between the moving body and the object fluctuates. It is an object of the present invention to provide a distance measuring device that can measure an accurate distance.

  In order to achieve the above object, the present invention provides a first light projecting means for projecting a first pulsed light having a substantially horizontal upper end portion and a light emitting region extending in the horizontal direction, and imaging for imaging an object. When the first pulse light is projected by the means and the first light projecting means so that the upper end portion of the first pulse light is applied to the object, the first pulse light is detected from the image captured by the image capturing means. Detecting means for controlling, detecting means for controlling detection by the detecting means, and upper edge detecting means for detecting the upper edge of the first pulse light applied to the object based on the first pulse light detected by the detecting means; The shape edge detection means for detecting the shape edge of the object from the image captured by the image pickup means and the distance to the object is calculated based on the upper edge and the shape edge in the specific light emission state with respect to the object. A distance calculating means, And wherein the door.

  In the distance measuring device according to the present invention, the first light projecting means projects the first pulse light so that the upper end of the object is applied to the object, and the image picked up by the imaging means at this time is detected and the upper end is detected. Detect edges. Further, the shape edge of the object is detected from the image picked up by the image pickup means in the specific light emission state. Then, the distance between the moving object and the object is calculated based on the upper edge and the shape edge. Therefore, even when the relative positional relationship between the moving body and the object fluctuates, the distance between the two can be calculated with high accuracy.

It is a block diagram which shows the structure of the distance measuring device which concerns on 1st Embodiment of this invention. It is a block diagram which shows the detailed structure of the synchronous detection process part used with the distance measuring device which concerns on 1st Embodiment of this invention. It is a timing chart which shows change of each signal in a synchronous detection processing part used with a distance measuring device concerning a 1st embodiment of the present invention. It is explanatory drawing which shows a mode that the distance to a measuring object is measured with the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the image imaged with the camera of the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the principle which measures the distance to a measuring object with the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the other example of a mode that the distance to a measuring object is measured with the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the other example of the image imaged with the camera of the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows a mode that the edge was extracted from the image imaged with the camera of the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows a mode that the distance to a measuring object is measured using two light projection parts with the distance measuring device which concerns on 1st Embodiment of this invention. It is explanatory drawing which shows the image imaged with a camera, when the pulsed light is projected by two light projection parts with the distance measuring device which concerns on 1st Embodiment of this invention. It is a flowchart which shows the procedure of the distance measurement process by the distance measuring device which concerns on 1st Embodiment of this invention. It is a flowchart which shows the procedure of the synchronous detection process by the distance measuring device which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the distance measuring device which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows a mode that the distance to a measuring object is measured with the distance measuring device which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows the image imaged with the camera of the distance measuring device which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the procedure of the distance measurement process by the distance measuring device which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows distance resolution in case the depression angle of the camera by the distance measuring device which concerns on embodiment of this invention is 0 degree. It is explanatory drawing which shows distance resolution in case the depression angle of the camera by the distance measuring device which concerns on embodiment of this invention is (alpha) degrees.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Description of First Embodiment]
FIG. 1 is a block diagram showing a configuration of a distance measuring apparatus 100 according to the first embodiment of the present invention. As shown in FIG. 1, the distance measuring device 100 according to the first embodiment is mounted on a moving body such as a vehicle, and emits region light toward a measuring object that is a target of distance measurement around the vehicle. A projection unit (first projection unit) 11 that irradiates, a camera (imaging unit) 12 that captures an image of the measurement object irradiated with the region light, and a projection that controls the irradiation of the region light by the projection unit 11. An optical control unit (control unit) 14, a synchronous detection processing unit (detection unit) 13 that performs synchronous detection processing on an image signal captured by the camera 12, and an upper edge ( An upper edge detection unit (edge detection means) 15 for detecting details will be described later, a shape edge detection unit 17 for detecting a shape edge (details will be described later) of an object to be measured from an image captured by the camera 12, and an upper edge Upper end detected by the detector 15 Tsu based on the detected shape edge di- and shape the edge detection unit 17, a distance calculation unit for determining the distance to the object of measurement (the distance calculation means) 16, a.

  The light projecting unit 11 is, for example, a headlight including a projector headlight or a reflector, and irradiates area light (first pulse light) having a light distribution characteristic that forms a light emitting area extending in the horizontal direction. The region light formed in the horizontal direction is subjected to BPSK modulation (details will be described later), and is subjected to PWM control to irradiate the measurement target, and the brightness boundary between the irradiation region and the non-irradiation region is clearly defined on the measurement target. Realize the light distribution. For example, it has the light distribution characteristic which has the brightness | luminance boundary shown with the code | symbol Y shown in FIG. Further, the light projecting unit 11 emits light of any one of visible light, infrared light, and ultraviolet light, or a combination thereof.

  The camera 12 includes, for example, an image sensor such as a CDD or a CMOS, and captures various images around the vehicle and receives reflected light from the measurement object of the region light emitted from the light projecting unit 11. In addition, the camera 12 has detection sensitivity for light of any one of visible light, infrared light, and ultraviolet light projected from the light projecting unit 11 or a combination thereof.

  The synchronous detection processing unit 13 uses a plurality of images acquired in time series from the camera 12 and, when all the pixels in the image or the processing area is limited in the image, in all the pixels in the processing area, Only the light synchronized with the PWM control is extracted from the region light irradiated from the light projecting unit 11. That is, only the light at the time of ON is extracted from the region light that is PWM-controlled and repeats ON (lights on) and OFF (lights off).

  The light projecting control unit 14 outputs a trigger signal for turning on and off the pulse when the light projecting unit 11 is PWM-controlled. Furthermore, a trigger signal for imaging timing by the camera 12 and a control signal for the shutter time of the camera 12 are output. Further, a carrier wave (carrier frequency; sin (ωt) described later) signal used in the above-described BPSK modulation is output to the synchronous detection processing unit 13.

  The upper edge detection unit 15 detects the upper edge of the region light based on the region light extraction image extracted by the synchronous detection processing unit 13. Specifically, as shown in FIG. 5, when the area light is irradiated onto the measurement object 31, the line r <b> 0 serving as the boundary of the area light on the measurement object 31 is detected as the upper edge. Details will be described later.

  The shape edge detection unit 17 acquires a signal indicating the timing without light irradiation by the light projecting unit 11 (PWM OFF timing) from the light projection control unit 14, and there is no region light irradiation by the light projecting unit 11. Using the image captured by the camera 12 below (specific light emission state), for example, the shape of the measurement object existing in the imaging range is extracted using known image processing such as a sobel filter. For example, as shown in FIG. 4, when the measurement object 31 exists in front of the vehicle, the shape (contour) of the measurement object 31 is extracted.

  The distance calculating unit 16 extracts pixels of the edge detected by the upper edge detecting unit 15 from a portion different from the shape edge detected by the shape edge detecting unit 17, and further, triangulation of the extracted pixel is performed. Using the principle, the distance to the measurement object is calculated based on the irradiation direction of the upper edge of the region light, the angle formed by the visual axis of the camera 12, and the layout. A detailed calculation procedure will be described later.

  Next, the basic principle of synchronous detection in the synchronous detection processing unit 13 will be described with reference to the block diagram shown in FIG. 2 and the timing chart shown in FIG. In general, synchronous detection is used as a process for robustly detecting only the irradiated region light. In the present embodiment, this synchronous detection processing is performed on all the pixels of the image captured by the camera 12 or all the pixels in the image region set as the processing region, and the irradiation light is extracted at each pixel. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 2, the transmission signal is a binary signal, and is represented by S (t) (t is time). For example, as shown in FIG. 3A, the binary signal S (t) changes between “1” and “0” at regular time intervals. When this binary signal S (t) is transmitted, a carrier wave sin (ωt) having a sufficiently high frequency ω with respect to the binary signal S (t) is phase-modulated with the binary signal S (t), and BPSK (Binary Phase Shift Keying: Two-phase shift keying) generates a transmission signal. As a result, a waveform as shown in FIG. 3B is generated and projected (see symbol q1 in FIG. 2). A sine wave is generally used as the carrier wave, and the amplitude modulation signal to be transmitted is 2 × (S (t) −0.5) × sin (ωt).

  On the other hand, on the light receiving side, the BPSK signal reflected by the measurement object is received (see symbol q2 in FIG. 2), and information on the carrier wave sin (ωt) used for transmission is used to obtain a binary signal S ( t) is extracted. That is, the binary signal S (t) is synchronously detected.

  Further, when the binary signal S (t) is extracted from the received signal, the received signal is multiplied by the carrier wave sin (ωt) (see symbol q3 in FIG. 2). The signal after this multiplication has a waveform as shown in FIG. Further, by multiplying the carrier wave sin (ωt), a signal component having a frequency twice as high as the carrier frequency ω is generated. In order to remove the influence, a high frequency is obtained using an LPF (low-pass filter). By removing the components and then making a positive / negative determination, the transmitted binary signal S (t) can be extracted as a decoded signal (an) as shown in FIG.

  Then, the state edge detector 15 detects the upper edge by comparing the transmission signal (binary signal S (t)) with the decoded signal (an). In the above description, the example in which the carrier wave sin (ωt) is phase-modulated with the binary signal S (t) has been described. However, other modulation schemes such as amplitude modulation and frequency modulation may be used.

  Next, the projection pattern of the area light projected from the light projecting unit 11 will be described. As described above, the light projecting unit 11 mounted on the vehicle Q irradiates the region light having a horizontal pattern with clear brightness on the upper end portion of the light projecting region. Hereinafter, this light distribution pattern will be described with reference to FIGS. FIG. 4 is an explanatory diagram showing a state in which the area light is irradiated toward the measurement target 31 from the light projecting unit 11 mounted on the vehicle Q, and FIG. It is explanatory drawing which shows the image imaged with the camera 12 at the time.

  Even if the relative positional relationship between the vehicle Q and the measurement object 31 changes due to the change of the posture of the vehicle Q or the movement of the measurement object 31, the region can be stably displayed. In order to extract light, as described above, in a time-series image frame necessary for detection, it is necessary to continuously observe an irradiation pattern at the same location on the measurement object.

  In reality, since there is no restriction on the movement of the vehicle and the measurement object 31, even when the vehicle and the measurement object 31 move arbitrarily, sufficient irradiation is performed to realize stable extraction of irradiation light. It is necessary to set the area of light. Therefore, in the present embodiment, as shown in FIG. 5, a light projection pattern having a light emitting region that extends in the horizontal direction (long in the horizontal direction) and a light projection region 51 in the lower region is used.

  Next, the principle of measuring the distance to the object using the upper edge of the area light will be described with reference to the schematic diagram shown in FIG. As shown in FIG. 6, the camera 12 is arranged at a position offset in a direction (vertical direction) perpendicular to the spreading direction (horizontal direction) of the region light irradiated from the light projecting unit 11. The area light projected from the light projecting unit 11 is irradiated onto the measurement object 31, and the camera 12 images the area light reflected on the surface of the measurement object 31. Here, measurement is performed based on the irradiation angle (0 degree in the example of FIG. 6) of the area light upper end of the light projecting unit 11, the distance (height difference) Dy between the light projecting unit 11 and the camera 12, and the depression angle α of the camera 12. Depending on the distance Z to the object 31, the vertical direction β at which the upper end of the region light is observed changes. Therefore, the distance Z to the measurement object 31 can be calculated by the principle of triangulation using the vertical position y at the upper end of the irradiation area observed by the camera 12.

  Based on the above principle, the distance Z from the camera installation position of the vehicle Q to the measurement object 31 can be obtained by irradiating the area light having the upper edge toward the measurement object 31 and receiving the reflected light. it can. However, in the case of using the above measurement method, there may be a measurement error as shown below. In this embodiment, the shape edge of the measurement object 31 is detected by the shape edge detection unit 17 and the shape edge is detected. The method of measuring the distance to the measuring object 31 using the is adopted.

  First, an example in which a measurement error occurs when calculating a distance using the above method will be described with reference to FIGS. FIG. 7 shows a case where the measurement object 31a higher than the upper end portion of the area light and the measurement object 31b lower than the upper end portion of the area light exist at the same distance in the direction in which the area light is projected. In this state, an image captured by the camera 12 is as shown in FIG. As for the measurement object 31a, the upper end of the area light projected from the light projecting unit 11 is synchronously detected as the upper edge r1, but the measurement object 31b is not the upper end of the area light but the measurement object. The upper end portion of 31b is synchronously detected as the upper end edge r2. When the distance is measured using this synchronous detection image, it is erroneously measured that the measurement object 31b exists at a closer distance even though the measurement object 31a and the measurement object 31b exist at the same distance. It will be.

  Therefore, in the present invention, based on the image captured by the camera 12 in the time zone in which the region light projected from the light projecting unit 11 is off (time zone in which the pattern light that is repeatedly turned on and off is turned off) Normal image processing is executed, the shape edges (contour lines) of the measuring objects 31a and 31b are detected, the horizontal edges are extracted from the shape edges, and the horizontal edges and the upper edge detected by the upper edge detection unit 15 The distance to the measurement objects 31a and 31b is measured by comparison with the above.

  For example, when an image in which the measurement objects 31a and 31b exist as shown in FIG. 9 is captured, the shape edge detection unit 17 detects the shape edges of the measurement objects 31a and 31b, thereby contouring them. And a horizontal edge is extracted from the shape edge. As a result, the horizontal edges r3 and r5 are extracted for the measurement object 31a, and the horizontal edges r4 and r6 are extracted for the measurement object 31b.

  When the shape edges of the measurement objects 31a and 31b detected by the shape edge detection unit 17 coincide with the upper edge detected by synchronous detection and detected by the upper edge detection unit 15, the distance measurement value includes an error. It can be determined that there is a possibility that That is, since the upper edge r1 of the measurement object 31a shown in FIG. 8 and the horizontal edge r3 of the measurement object 31a shown in FIG. 9 do not coincide (the heights are different), the upper edge r1 in FIG. 8 is used. When measuring the distance, it can be determined that no error is included. On the other hand, since the upper edge r2 of the measurement object 31b shown in FIG. 8 and the horizontal edge r4 of the measurement object 31b shown in FIG. 9 coincide (having the same height), the upper edge r1 in FIG. It is determined that there is a possibility that an error is included when the distance is measured by using it.

  In this case, the information indicating that the measurement object 31b exists is output, but the distance measurement value is output as a reference value assuming that an error is included, and is not used for subsequent vehicle control.

  Next, the operation of the distance measuring apparatus according to the first embodiment of the present invention will be described with reference to the flowchart shown in FIG.

  First, in step S1, an image of the measurement object 31 existing around the vehicle is acquired by the camera 12.

  In step S2, it is determined whether the image acquired in the process of step S1 is an image captured at a timing at which the region light irradiated by the PWM control from the light projecting unit 11 is not irradiated. If it is a captured image of (specific light emission state), the process proceeds to step S8, and if it is a captured image when irradiated, the process proceeds to step S3.

  In step S8, the shape edge detection unit 17 performs shape edge detection processing of normal image processing, and further transfers the data of the shape edge to the distance calculation unit 16 in FIG.

  In step S3, a synchronous detection process flow is executed. Thereafter, the process proceeds to step S4. The synchronous detection processing flow will be described later with reference to the flowchart shown in FIG.

  In step S4, the upper edge detection unit 15 extracts the upper edge part of the synchronously detected area.

  In step S5, from the upper edge detected in step S4, the shape edge extracted in step S8, that is, the same part as the shape edge extracted in shape edge detector 17 is removed. To do. That is, as described above, since r2 in FIG. 8 and r4 in FIG. 9 coincide, they are removed.

  In step S6, the distance calculation unit 16 performs a distance calculation calculation process by triangulation, calculates the distance between the vehicle Q and the measurement object 31, and outputs this distance data to the host system.

  Next, the synchronous detection process executed in the process of step S3 in FIG. 12 will be described with reference to the flowchart shown in FIG.

  First, synchronous detection processing is started in step S11, and in step S12, a carrier wave sin (ωt) defined by the light projection control unit 14 for the acquired image (image captured by the camera 12) (FIG. 2) is mixed. Specifically, all pixels set in the processing area in the image are multiplied by a sine wave in a phase corresponding to the acquisition timing.

  In step S <b> 13, an image obtained by mixing the carrier wave sin (ωt) is stored in a frame memory (not shown) included in the synchronous detection processing unit 13. When performing continuous detection processing, if n consecutive frames of images are required, a frame memory for n frames is secured. For example, the oldest image data is updated with the latest image data by a ring buffer structure. To do.

  In step S14, time-series data of pixel data at a predetermined address is read from the image data stored in the frame memory. For example, assuming that the pixel data of the pixel position (xi, yj) acquired at the latest time t is I (xi, yj, t), the data for the latest n pixels used for synchronous detection, I (xi, yj, t ), I (xi, yj, t−1),..., I (xi, yj, t−n + 1).

  In step S15, a low-pass filter (see LPF in FIG. 2) is applied.

  In step S16, positive / negative determination is performed on the time-series data of the pixels to which the low-pass filter is applied. For example, “1” is assigned if the pixel value is positive, and “0” is assigned if the pixel value is negative, and the transmitted signal sequence (bit sequence) an is restored.

  In step S17, it is determined whether or not the detection has been completed for all the pixels in the processing region. If the detection processing has not been completed for all the pixels in the processing region (NO in step S17), the process proceeds to step S14. The processing is returned, the time-series pixel data at the next pixel position (for example, (xi + 1, yj)) is read, and the processing from step S15 is repeated.

  If the detection process has been completed for all the pixels (YES in step S17), the synchronous detection image is output in step S18 and the process ends. In this way, the distance between the vehicle Q and the measurement object 31 can be obtained based on the upper edge detected by the upper edge detection unit 15.

  In this way, in the distance measuring device according to the present embodiment, the light projecting unit 11 projects the region light having the light emission pattern having the light emitting region extending in the horizontal direction, and the camera 12 uses the measurement object 31. The reflected area light is imaged, and the captured area light is synchronously detected to extract the upper edge from the image of the measurement object 31 captured when the light emission pattern is on. And based on this upper end edge, the distance between the vehicle Q and the measuring object 31 is calculated using the principle of triangulation. Therefore, even when the vehicle Q and the measurement object 31 move relatively, the light emission pattern spreading in the horizontal direction is used, so that the upper edge can be detected with a high probability, and a highly accurate distance can be obtained. Measurement is possible.

  Further, the shape edge detection unit 17 detects the shape of the measurement object 31, further extracts the shape edge, and if this shape edge coincides with the upper edge detected by the upper edge detection unit 15, There is a high possibility that the upper edge is an edge indicating the shape of the measurement object 31, and there is a high possibility that the upper edge will contain an error. Therefore, the distance measurement using this upper edge is not performed. Accordingly, it is possible to eliminate data that is highly likely to contain errors, and to measure distances with higher accuracy.

  In addition, as the synchronization signal used in the light projecting unit 11 and the synchronous detection processing unit 13, it is possible to use amplitude modulation, phase modulation, and frequency modulation, and further use BPSK that is a combination of amplitude modulation and phase modulation. Thus, robustness can be improved.

  Furthermore, since the light source provided in the light projecting unit 11 emits infrared light or ultraviolet light, the irradiation light can be made more robust by configuring the camera 12 with a filter that transmits light of a specific spectrum with high efficiency. It becomes possible to detect. Further, it is possible to prevent dazzling without disturbing the visual recognition of others by irradiation with pulsed light.

[Description of modification]
Next, a modification of the first embodiment described above will be described. Although 1st Embodiment demonstrated the example which projects the area light which has a single light projection pattern from the one light projection part 11, in this modification, two area light from which a depression angle differs is measured object By projecting light toward 31a and 31b, the distance measurement accuracy is further improved. Hereinafter, a description will be given with reference to FIGS.

  FIG. 10 is an explanatory diagram illustrating a state in which area light is projected from the light projecting unit 11 of the distance measuring device according to the modification toward the measurement objects 31a and 31b, and the light projecting unit 11 has a substantially horizontal depression angle. The first region light u1 and the second region light u2 having a depression angle are irradiated. As a result, the synchronously detected image is as shown in FIG. 11, and the two upper edges r11 and r12 are extracted from the measurement object 31a, and the two upper edges r13 and r14 are extracted from the measurement object 31b. become.

  As can be understood from FIG. 11, by using the light projecting unit 11 that irradiates a plurality of (two in this example) region lights having different depression angles, the upper end portion of the at least one region light has the above shape. Unlike the edge, accurate distance measurement can be performed.

  Specifically, since the upper edges r11 and r13 obtained by projecting the region light u1 do not coincide with each other, the distance measurement using the upper edge is highly likely to include an error, and the region light u2 Since the upper edges r12 and r14 obtained by projecting coincide with each other, it can be used for distance measurement.

  As described above, in the distance measuring device according to the modified example, the distance between the vehicle Q and the measurement objects 31a and 31b is measured by projecting the two region lights having different depression angles, so that the distance is further improved. Can be measured.

  Next, it will be described that the resolution can be improved by setting the visual axis of the camera 12 to have a predetermined depression angle with respect to the direction in which the upper edge is irradiated.

  In order to observe a wide area with one camera 12, a wide-angle lens is usually used. A general wide-angle lens employs an equidistant projection lens (so-called fθ lens) as a projection method, and the peripheral visual field has a lower resolution than the central visual field. In combination with such a wide-angle lens, it is important that the camera viewing axis has a depression angle (or elevation angle) and an area with high resolution is set appropriately for the area to be monitored.

  Hereinafter, for the sake of simplicity in the combination with the fθ lens, it is assumed that the upper edge of the irradiated light is horizontal with respect to the road surface, and the distance measurement value to the object to be observed when there is a depression angle of the camera visual axis. The improvement of the resolution will be described with reference to FIGS. FIG. 18 shows a case where there is no depression angle on the camera viewing axis, and FIG. 19 shows a case where there is a depression angle.

  18 and 19, the pixel position in the visual axis direction is y (j), and the pixel position adjacent to y (j) is y (j + 1). At this time, as shown in FIG. 18, when the depression angle (elevation angle) is 0 degree, the angular resolution of one pixel determined by the pixel positions y (j) and y (j + 1) is the distance resolution at the real space distance. Let dD (0). On the other hand, as shown in FIG. 19, when the depression angle (elevation angle) is α degrees, the angular resolution of one pixel determined by the pixel positions y (j) and y (j + 1) is the distance resolution dD at the real space distance. Assume that (α). In this case, since dD (α) <dD (0) is established, when the depression angle (elevation angle) is given to the camera visual axis, the real space resolution with respect to the angular resolution of one pixel is increased. That is, by providing the depression angle α, it is possible to increase the real spatial resolution when extracting the upper edge.

  As described above, the upper edge of the region light projected by the light projecting unit 11 is formed in a region lateral to the camera 12, and the camera 12 is offset in a direction perpendicular to the upper edge irradiation direction. Measurement accuracy when distance is measured based on the principle of triangulation even when a general wide-angle lens (fisheye lens) is used, as long as the top edge irradiation direction and the visual axis form a predetermined angle. Will improve.

[Description of Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 14 is a block diagram showing the configuration of the distance measuring apparatus 101 according to the second embodiment of the present invention. Compared with the apparatus shown in FIG. 1 described above, the distance measuring apparatus 101 according to the second embodiment has two light projecting units, that is, a Hi beam projecting unit (second projecting means) 18 and a Lo beam projecting unit. The difference is that a light unit (first light projecting means) 19 is provided and a Hi beam light projection control unit 21 is provided. The other configurations are the same as those in FIG.

  The Hi beam projecting unit 18 projects area light having an elevation angle and irradiates the entire observation area of the camera 12 with light. In addition, the Hi beam projection control unit 21 controls the Hi beam projection unit 18 so that the number of projections is one or more for each number of frames necessary for one synchronous detection process.

  The shape edge detection unit 17 detects the shape edge of the measurement object from the image captured by the camera 12 when the measurement object is irradiated with light from the Hi beam projecting unit 18 (specific light emission state).

  The Lo beam light projecting unit 19 projects area light having a depression angle of 0 ° or a depression angle, similar to the projection unit 11 shown in FIG.

  Then, the shape edge detected by the shape edge detection unit 17 is used as the shape edge detected by the shape edge detection unit 17 (see FIG. 1) of the first embodiment described above. That is, the distance is measured in consideration of the coincidence and mismatch between the shape edge detected by the shape edge detection unit 17 shown in FIG. 14 and the upper edge detected by the upper edge detection unit 15.

  Further, as described above, the area light projection by the Hi beam projecting unit 18 is performed at a rate of one or more for each number of frames necessary for one synchronous detection process, so that the first implementation is performed. Error detection equivalent to the form can be realized.

  FIG. 15 is an explanatory diagram showing a state when the region light is irradiated from the Hi beam projecting unit 18 toward the measurement objects 31a and 31b. As shown in the figure, the light pattern projected from the Hi beam projecting unit 18 has an elevation angle, and irradiates the region light over almost the entire region imaged by the camera 12.

  FIG. 16 is an explanatory diagram showing an image captured by the camera 12 when the Hi beam is irradiated, and the respective horizontal edges r21 and r22 of the measurement objects 31a and 31b can be detected. Then, by comparing the horizontal edges r21 and r22 with the above-described upper end edges r1 and r2 of FIG. 8, it is possible to recognize coincidence and mismatch.

  Next, the operation of the distance measuring apparatus 101 according to the second embodiment will be described with reference to the flowchart shown in FIG. Note that steps S1 to S4 and steps S5 and S6 shown in FIG. 17 are the same as those in FIG.

  When the upper edge of the synchronous detection image is extracted in step S4 shown in FIG. 17, in step S21, the image of the light pattern projected from the Hi beam projector 18 within the image acquisition time used for the synchronous detection process. It is determined whether or not exists.

  If it exists, the process proceeds to step S5. If not, the process proceeds to step S22. In step S5, the same processing as in FIG. 13 is executed.

  In step S <b> 22, the Hi beam projecting unit 18 projects area light having an elevation angle under the control of the Hi beam projecting control unit 21. In step S23, shape edges are extracted from the image captured by the camera 12.

  In step S24, the extracted shape edge is stored. Thereafter, the process proceeds to step S5. In step S5, the shape edge stored in the process of step S24 is removed from the top edge subjected to synchronous detection. That is, by removing the edges indicating the shapes of the measurement objects 31a and 31b, only the upper edge indicating the upper end of the region light is left, and the upper edge is used to between the vehicle Q and the measurement objects 31a and 31b. The distance is calculated.

  Thus, in the distance measuring device 101 according to the second embodiment, the shape edges of the measurement objects 31a and 31b are detected using the region light projected from the Hi beam projecting unit 18, and therefore the surroundings are dark. Even in the case described below or when the sensitivity of the camera 12 is poor, the shape edges of the measurement objects 31a and 31b can be detected with high accuracy, and a robust and accurate distance measurement is possible.

  In addition, it is possible to use visible light, infrared light, etc. as the wavelength of the light projected from the light projection part 11, In that case, the camera 12 used the element which can observe the wavelength to project. It should be.

  The distance measuring device of the present invention has been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each part is replaced with an arbitrary configuration having the same function. Can do.

  For example, in each of the above-described embodiments, the automobile has been described as an example of the moving body.

  The present invention can be used to measure the distance to the measurement object with high accuracy.

DESCRIPTION OF SYMBOLS 11 Light projection part 12 Camera 13 Synchronous detection process part 14 Light projection control part 15 Upper end edge detection part 16 Distance calculation part 17 Shape edge detection part 18 Hi beam light projection part 19 Lo beam light projection part 21 Hi beam light projection control part 31 , 31a, 31b Measurement object 51 Projection area 100, 101 Distance measuring device Q Vehicle

Claims (6)

A first light projecting means for projecting a first pulse light mounted on a moving body, having a substantially horizontal upper end portion and having a light emitting region extending in a horizontal direction;
An imaging means mounted on the moving body for imaging an object;
When the first pulsed light is projected by the first light projecting unit so that the upper end portion of the first pulsed light is applied to the object, the first pulsed light is obtained from the image captured by the imaging unit. Detecting means for detecting
Control means for controlling detection by the detection means;
Upper edge detection means for detecting an upper edge of the first pulse light applied to the object based on the first pulse light detected by the detection means;
A shape edge detecting means for detecting a shape edge of the object from an image picked up by the image pickup means in a specific light emission state with respect to the object;
Distance calculating means for calculating the distance between the object and the moving body based on the upper edge and the shape edge;
A distance measuring device comprising:   The distance measuring device according to claim 1, wherein the specific light emission state is a state in which the first pulse light is not projected.   The second light projecting means for irradiating the object with light, and the specific light emission state is a state in which the object is irradiated with light by the second light projecting means. The distance measuring apparatus according to 1.   The control unit and the detection unit control the first light projecting unit and the imaging unit using at least one of amplitude modulation, phase modulation, and frequency modulation as a detection signal. The distance measuring device according to any one of claims 1 to 3.   The first light projecting unit includes a light source that emits at least one of visible light, infrared light, and ultraviolet light, and the imaging unit has a visible light region, an infrared region depending on the light source. 5. The distance measuring device according to claim 1, wherein the distance measuring device has sensitivity in at least one of the ultraviolet region and the ultraviolet region.   The distance measurement according to any one of claims 1 to 5, wherein the imaging unit is provided in a vertical direction with respect to the first light projecting unit, and the shooting direction has a predetermined depression angle. apparatus.