JP3790048B2 - Object detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an object detection apparatus that is small, lightweight, and excellent in vibration resistance suitable for an automatic driving system for a moving body.
[0002]
[Prior art]
As a conventional object detection device, a method using an ultrasonic reflected wave, a method of detecting the discontinuity of a light beam in an image irradiated with a light beam, and recognizing the presence of an object, a device using a so-called light cutting method, etc. There is.
However, in the case of ultrasonic waves, the measurement distance is short with a limit of about 5 to 10 m, and the shape of the object cannot be recognized.
[0003]
In this respect, the light cutting method can detect even a long-distance object and can recognize the shape.
The principle of object detection by the light cutting method will be described. A laser beam is scanned in the object detection area, and an image in the object detection area is captured by the camera. If there is no object ahead, the scan line of the laser light in the captured image is a continuous straight line. When an object exists, the scan line of the laser beam becomes discontinuous from the distance difference between the object and the background, and the presence of the object can be recognized. Furthermore, if the positional relationship between the mounting angle and mounting position of the imaging device, the laser beam irradiation angle and the irradiation position, etc. is known, the XY orthogonal coordinate value of the scan line in the image is used to determine the object based on the principle of triangulation. The distance can be obtained, and the shape of the object can also be recognized by converting the XY orthogonal coordinate values into a three-dimensional cylindrical coordinate system.
[0004]
[Problems to be solved by the invention]
However, in the conventional light cutting method, the scanning scan of the laser beam generally uses a heavy polygon mirror, which is rotated by a motor. Further, in order to prevent the optical axis from being shifted due to vibration or the like, it is necessary to increase the rigidity of the support mechanism, and the support mechanism must be sturdy. For this reason, it is difficult to downsize the laser beam scanning mechanism, and the power consumption is also large. Accordingly, there is a strong demand for downsizing, weight reduction, and further power saving, and it is difficult to use it for obstacle detection by mounting it in a car or the like that is constantly subjected to vibration.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an object detection apparatus that is small, lightweight, and excellent in vibration resistance that can be mounted on a moving body such as an automobile.
[0006]
[Means for Solving the Problems]
Therefore, in the object detection apparatus according to claim 1, the laser beam from the laser beam oscillation source that intermittently emits the laser beam is reflected, and the reflected laser beam is scanned two-dimensionally with respect to the object detection region. A semiconductor galvanometer mirror, two CCD cameras which are installed at a predetermined interval in the horizontal direction and respectively image the object detection region, and laser light scanning images captured by the CCD cameras. When the optical scanning image becomes discontinuous, the orthogonal coordinate value of the discontinuous part on the CCD is calculated, converted into a three-dimensional coordinate system, and the light section recognition processing is executed to recognize the shape and position of the object. A stereo method recognition process for recognizing the shape and position of the object from the difference between the two laser light scanning images is executed, and when the recognition result of the light cutting method recognition process substantially matches the recognition result of the stereo method recognition process Recognition Results and image processing means for the shape and position of the object, a blur detecting means for detecting a shake of the semiconductor galvano mirror, by the light section method recognition of the image processing unit based on a detection result of said shake detecting means And a correction means for correcting the calculated coordinate position.
[0007]
In such a configuration, the semiconductor galvanomirror driving rotation, while two-dimensionally scanning the laser beam relative to the object detection region from the laser beam oscillation source, in two CCD cameras, laser beam is scanned Capture the image of the object detection area. The image processing means determines that there is an object if the scanned image of the laser light in the captured image is discontinuous. And the orthogonal coordinate value of the discontinuous laser beam scanning line is calculated from the image. At this time, the shake detection means detects shake caused by the vibration of the semiconductor galvanometer mirror when scanning the laser beam, and the correction means calculates the orthogonal coordinate value calculated based on the detection value from the shake detection means. Correct. The image processing means converts the correction value of the orthogonal coordinates into a three-dimensional coordinate system, and recognizes the shape and position of the object by the light cutting method recognition processing . Further, the image processing means recognizes the shape and position of the object by stereo method recognition processing for recognizing the shape and position of the object from the difference between the scanned images of the two laser beams. If the two recognition processing results substantially match, the recognition result is determined as the shape and position of the object.
[0008]
Further, the invention according to claim 2 is mounted on a moving body.
By mounting such an object detection device on a moving body, an obstacle around the moving body can be detected with high accuracy. Moreover, since it is small and lightweight, it can be easily mounted on a moving body.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic block diagram showing an embodiment of an object detection apparatus according to the present invention.
In FIG. 1, CCD cameras 1 and 11 are installed at a predetermined interval in the horizontal direction, and an object detection area is photographed by two CCD cameras 1 and 11 as if a human is looking with both eyes . Image information captured by the CCD cameras 1 and 11 is input to the image processing unit 3 through the image signal input / output unit 2 as a digital image signal. The image processing unit 3 performs image processing for recognizing the shape and position of an object by a light cutting method described later. The image processing unit 3 uses a so-called stereo method known in the art, which simultaneously captures an object from the light detection method and captures images from different directions using two cameras and recognizes the shape and position of the object from the difference. Perform object detection processing. Further, after the image processing by the image processing unit 3, the processed image is displayed on the monitor 4 via the image input / output unit 2. The laser beam oscillator 5 which is a laser beam oscillation source is controlled to be intermittently oscillated by the laser driving unit 6. The semiconductor galvanometer mirror 200 is rotationally driven by the galvanometer mirror drive controller 7 at a predetermined cycle, reflects the laser beam from the laser beam oscillator 5 and scans the object detection region two-dimensionally. The controller 8 controls the driving and timing of the image input / output unit 2, the image processing unit 3, the laser driving unit 6, and the galvano mirror drive control unit 7, and based on the image processing data from the image processing unit 3, Various operations are performed to determine the shape and position, and the shape and position of the object are determined.
[0010]
As will be described later, the semiconductor galvanometer mirror 200 has a function as a shake detection means for detecting a shake (displacement angle) of the mirror caused by vibration or the like, and feeds back the detected shake information to the controller 8. The controller 8 corrects image processing data (orthogonal coordinate values described later) from the image processing unit 3 based on the shake value from the semiconductor galvanometer mirror 200. Here, the image processing unit 3 and the controller 8 constitute an image processing means. The controller 8 also has a function of a correction unit.
[0011]
Next, a specific configuration of the semiconductor galvanometer mirror will be described.
The semiconductor galvanometer mirror 200 is manufactured using a semiconductor manufacturing technique. This semiconductor galvanometer mirror 200 has been previously proposed by the present applicant in Japanese Patent Laid-Open Nos. 7-175005 and 7-218857, and is described in detail in the above-mentioned publications. Let's briefly explain.
[0012]
FIG. 2 shows an exploded perspective view of an example of a semiconductor galvanometer mirror applied to this embodiment.
In FIG. 2, a semiconductor galvanometer mirror 200 has an outer movable plate 204A supported on a silicon substrate 201 so as to be swingable in the vertical direction of the substrate by a torsion bar 205A, and an inner movable plate 204B is disposed inside the outer movable plate 204A. The torsion bar 205A is pivotally supported by a torsion bar 205B whose axial direction is orthogonal to the upper and lower directions of the substrate. The outer movable plate 204A is formed in a frame shape, and a planar coil 206A (electrically connected to a pair of outer electrode terminals 209A and 209A formed on the upper surface of the silicon substrate 201 on one surface of the outer movable plate 204A via one portion of the torsion bar 205A. In the figure, a single line) is schematically covered with an insulating layer. The inner movable plate 204B is formed in a flat plate shape, and a pair of inner electrode terminals 209B and 209B formed on the silicon substrate 201 is formed on the upper surface of the inner movable plate 204B from one of the torsion bars 205B through the outer movable plate 204A. A planar coil 206B (schematically shown as a single line in the figure) electrically connected via the other side of 205A is provided so as to be covered with an insulating layer. A mirror 208 is formed at the center of the inner movable plate 204B surrounded by the planar coil 206B.
[0013]
Upper and lower glass substrates 202 and 203 made of borosilicate glass, for example, are anodically bonded to the upper and lower surfaces of the silicon substrate 201, respectively. The upper glass substrate 202 has a rectangular opening 202A at the center of the flat plate portion, and has a shape in which the upper portion of the movable plate is opened. The lower glass substrate 203 has a square groove 203A at the center of the flat plate portion, and the detection coils 214A and 214B for detecting the displacement of the outer movable plates 204A and 204B based on the mutual inductance with the planar coils 206A and 206B. 214B is provided symmetrically with respect to the torsion bars 205A and 205B. The upper and lower glass substrates 202 and 203 and the silicon substrate 201 have a three-layer structure so as to ensure a swinging space for both movable plates 204A and 204B.
[0014]
On the upper and lower glass substrates 202 and 203, two permanent magnets 210A to 213A and 210B to 213B in pairs of two are arranged as shown in the figure. The permanent magnets 210A and 211A facing each other on the upper glass substrate 202 generate a magnetic field for driving the outer movable plate with the permanent magnets 210B and 211B on the lower glass substrate 203. Further, the permanent magnets 212A and 213A facing each other on the upper glass substrate 202 generate a magnetic field for driving the inner movable plate with the permanent magnets 212B and 213B of the lower glass substrate 203.
[0015]
Next, the operation principle of the semiconductor galvanometer mirror 200 will be briefly described.
For example, a current is passed through the planar coil 206A with one of the electrode terminals 209A and 209A serving as a positive pole and the other serving as a negative pole. On both sides of the outer movable plate 204A, the permanent magnets 210A and 210B and the permanent magnets 211A and 211B form a magnetic field in a direction crossing the planar coil 206A along the plane of the outer movable plate 204A. When a current flows through the planar coil 206A in the magnetic field, the current, the magnetic flux density, and the force framing in the direction according to the left hand rule at the both ends of the outer movable plate 204A according to the current density and the magnetic flux density of the planar coil 206A. A force acts, and the outer movable plate 204A rotates. When the outer movable plate 204A rotates, the torsion bar 205A is twisted, and the outer movable plate 204A rotates to a position where the spring reaction force of the torsion bar 205A generated thereby and the electromagnetic force acting on the outer movable plate 204A balance. Move.
[0016]
The displacement angle of the outer movable plate 204A at this time is proportional to the current flowing through the planar coil 206A. Therefore, the displacement angle of the outer movable plate 204A, that is, the mirror 208 can be controlled by controlling the current flowing through the planar coil 206A. If the relationship between the amount of current flowing through the planar coil and the displacement angle of the movable plate is obtained in advance, the mirror 208 can be set at a desired displacement angle position by controlling the amount of current.
[0017]
The inner movable plate 204B rotates about the torsion bar 205B on the basis of the same operating principle as the outer movable plate 204A, and the displacement angle can be controlled by controlling the amount of current flowing through the planar coil 206B.
Thus, by controlling the rotation of the outer and inner movable plates 204A and 204B, the reflection direction of the laser beam by the mirror 208 can be variably controlled. Then, for example, the inner movable plate 204B is rotated to scan the laser beam in the horizontal direction, and the outer movable plate 204A is rotated to scan the laser beam in the vertical direction, thereby making the object detection region two-dimensionally. Can be scanned.
[0018]
Further, when controlling the displacement angle of the mirror 208, a displacement angle detection current having a frequency higher than the drive current frequency is passed through the planar coil 206A in a manner superimposed on the drive current. Then, based on this detection current, induced voltages due to mutual inductance between the planar coil 206A and the detection coils 214A and 214B provided on the lower glass substrate 203 are generated in the respective detection coils 214A and 214B. When the outer movable plate 204A is in the horizontal position, the induced voltages generated in the detection coils 214A and 214B have the same distance between the detection coils 214A and 214B and the corresponding planar coil 206A, and the difference between them is zero. When the outer movable plate 204A is rotated around the torsion bar 205A by electromagnetic force, one detection coil 214A (214B) approaches and the induction voltage increases due to an increase in mutual inductance, and the other detection coil 214B (214A) moves away. As a result, the induced voltage decreases due to the decrease in mutual inductance. Therefore, the induced voltage generated in both detection coils 214A and 214B changes in accordance with the displacement angle of the movable plate, and the displacement angle of the movable plate, that is, the mirror 208 can be detected by detecting this induced voltage. Then, for example, an induced voltage difference generated in both detection coils 214A and 214B is fed back to the controller 8 through a differential amplifier using a bridge circuit or the like. If the relation data between the induced voltage difference and the mirror displacement angle is stored in advance, the mirror displacement angle can be known from the fed back induced voltage difference value, and the set value of the mirror displacement angle at that time Deviation can be detected.
[0019]
Next, the operation of the object detection device of this embodiment will be described.
The controller 8 drives and controls the laser driving unit 6, and laser light is intermittently emitted from the laser light oscillator 5 to the semiconductor galvanometer mirror 200. In the semiconductor galvanomirror 200, the inner movable plate 204B and the outer movable plate 204B are rotationally driven and controlled by the galvanomirror drive control unit 7 according to a command from the controller 8, and the incident laser light is indicated by an arrow a in FIG. The object detection area is scanned in the horizontal direction, and further scanned in the vertical direction as indicated by the arrow b in FIG. 3 to scan the object detection area in a two-dimensional manner.
[0020]
The CCD camera 1 sequentially captures the image of the object detection area at a timing synchronized with the oscillation of the laser beam, and the digital image signal from the CCD camera 1 is transmitted to the image processing unit 3 via the image signal input / output unit 2. . The video captured on the monitor 4 based on the image information from the image processing unit 3 is displayed.
Then, for example, as shown in FIG. 3, when the objects A and B exist in the object detection area and the laser beams are radiated to the objects A and B as indicated by solid lines in the figure, they are captured by the CCD camera 1 In the image, as shown in FIG. 4, the scanning line of the laser beam becomes a discontinuous line due to the difference in distance between the background and the objects A and B. Image processing for recognizing the position and shape of the object is performed from this image by a light cutting method, and processing data is input to the controller 8. The same processing as in the case of the CCD camera 1 is performed on the digital image signal from the CCD camera 11.
[0021]
In the image processing unit 3, for each image captured by each CCD camera 1, 11, for example, a coordinate value calculation process of a laser beam irradiation point of an object is performed in the same manner as image processing performed in a conventionally known light cutting method. Done.
The light cutting method is conventionally known, and will be briefly described here with reference to FIGS. 5 and 6.
5 and 6, the laser irradiation direction is the X axis, the height direction is the Y axis, and the scanning direction (lateral direction) is the Z axis. The focal position of the CCD camera 1 is F, the irradiation angle of the laser beam with respect to the ground and the tilt angle of the camera 1 are α and β, respectively, and the scanning angle of the laser beam is θ. Further, 1A is assumed to be the CCD surface of the CCD camera.
[0022]
The inclination angle β is determined by the mounting angle of the camera. The laser beam irradiation angle α is determined from the laser beam irradiation direction from the laser beam oscillator 5 and the displacement angle of the semiconductor galvanometer mirror 200. Since the laser beam irradiation direction is fixed, it is determined from the displacement angle α of the semiconductor galvanometer mirror 200. Can do.
In FIG. 5, a laser beam irradiation point M on an object in the XY plane is obtained. This can be achieved by obtaining the intersection of the linear equation Y1 of the laser beam and the linear equation Y2 connecting the focal point F and the irradiation point M. In the linear equation Y1, the laser beam emission point N is known and can be determined from the laser beam irradiation angle α. The linear formula Y2 can be obtained from the coordinate value of the irradiation point of the laser beam reflected on the CCD surface 1A and the coordinate value of the focal point F, and the coordinate value on the CCD surface 1A is determined based on the number of pixels in the vertical direction of the CCD and the camera. It can be obtained from the inclination angle β. Thereby, the linear equations Y1 and Y2 can be known, and the laser beam irradiation point M is obtained by calculating the intersection of both straight lines.
[0023]
Next, in FIG. 6, a laser light irradiation point M on an object in the XZ plane is obtained. This may be obtained by obtaining the intersection of the linear equation Y3 of the laser beam and the linear equation Y4 connecting the focal point F and the irradiation point M. The linear formula Y3 can be obtained from the scanning angle θ of the laser beam and the X coordinate value of the irradiation point M obtained in FIG. The linear formula Y4 can be obtained from the coordinate value of the irradiation point of the laser beam reflected on the CCD surface 1A and the coordinate value of the focal point F, and the coordinate value on the CCD surface 1A is determined by the number of pixels in the horizontal direction of the CCD. Thereby, the linear equations Y3 and Y4 can be known, and the coordinate value of the laser beam irradiation point M on the XZ plane can be obtained by calculating the intersection of both straight lines.
[0024]
The calculated coordinate value data is input to the controller 8. The controller 8 converts the input coordinate value data into a three-dimensional coordinate system, and determines the actual shape and position of the object from the three-dimensional coordinate information. At this time, when the semiconductor galvanometer mirror 200 is shaken by vibration or the like, the laser beam is shaken as shown by a dotted line in FIG. For this reason, this blur amount is detected and fed back to the controller 8 by the blur detection function of the semiconductor galvanometer mirror 200. The controller 8 corrects the orthogonal coordinate value from the image processing unit 3 based on this feedback information, converts it to a three-dimensional coordinate system, and determines the actual shape and position of the object from the three-dimensional coordinate information.
The shape and position of the object are determined in the same manner for the image captured by the CCD camera 11. Then, the final object shape and position are determined by combining both object detection processing results. Simultaneously with the object detection processing by the light cutting method, the object detection processing by the conventionally known so-called stereo method for recognizing the shape and position of the object from the difference between the images captured by the two CCD cameras 1 and 11 from different directions. I do. Furthermore, the object information obtained from the light cutting method and the object information obtained from the stereo method are compared, and the coincidence / non-coincidence of the recognition results of the both is determined. When the two substantially coincide, the final object shape and position are determined. To do.
[0025]
For example, when this object detection device is mounted on an automobile and applied to an obstacle detection device, when there is a need to avoid a recognized obstacle, the obstacle recognition information output from the controller 8 It is preferable to configure a control system that automatically performs the avoidance operation.
According to such a configuration, not only can the shape and position of the object be recognized and the object can be detected with high accuracy, but also the semiconductor galvanometer mirror 200 is used to scan the laser beam, so compared with the case where a conventional polygon mirror is used. The laser beam scanning mechanism can be significantly reduced in size and weight, and the power consumption can be greatly reduced. Further, it is possible to correct the blur of the laser beam caused by vibration or the like. Therefore, it is suitable to be mounted on an automobile or the like and applied as an obstacle detection device.
[0029]
【The invention's effect】
As described above, according to the first aspect of the present invention, the laser light is scanned using the semiconductor galvanometer mirror manufactured using the semiconductor manufacturing technology, so that the laser light scanning mechanism is significantly reduced in size and weight. Power consumption can be greatly reduced. Also, since the coordinate position is corrected by detecting the blur of the laser beam, the shape and position of the object can be detected with high accuracy.
[0030]
As described in claim 2, when it is mounted on a moving body or the like that is easily affected by vibration, it is possible to reduce false detection due to the influence of vibration or the like, which is suitable for detecting an obstacle around the moving body.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of an embodiment of an object detection apparatus of the present invention. FIG. 2 is an explanatory diagram of a semiconductor galvanometer mirror. FIG. 3 is a scanning operation diagram of a laser beam. FIG. 5 is a diagram illustrating a state of a laser beam scanning line in the above. FIG. 5 is an explanatory diagram of coordinate value calculation by the light cutting method of the present embodiment. FIG. 6 is an explanatory diagram of coordinate value calculation by the light cutting method of the present embodiment. Explanation of]
DESCRIPTION OF SYMBOLS 1,11 CCD camera 3 Image processing part 5 Laser light oscillator 6 Laser drive part 7 Galvano mirror drive control part 8 Controller 200 Semiconductor galvano mirror

Claims (2)

A semiconductor galvanometer mirror that reflects laser light from a laser light oscillation source that emits laser light intermittently and scans the reflected laser light two-dimensionally with respect to an object detection region;
Two CCD cameras installed at predetermined intervals in the horizontal direction and imaging each of the object detection areas;
Based on each laser beam scanning image captured by each CCD camera, the orthogonal coordinate value of the discontinuous portion on the CCD when the laser beam scanning image becomes discontinuous is calculated and converted to a three-dimensional coordinate system. The light cutting method recognition process for recognizing the shape and position of the object is executed, the stereo method recognition process for recognizing the shape and position of the object from the difference between the two laser light scanning images is executed, An image processing means for setting the recognition result to the shape and position of the object when the recognition result and the recognition result of the stereo method recognition process substantially coincide with each other ;
Blur detection means for detecting blur of the semiconductor galvanometer mirror;
Correction means for correcting the coordinate position calculated in the light cutting method recognition processing of the image processing means based on the detection result of the shake detection means;
An object detection device characterized by comprising:   The object detection apparatus according to claim 1, wherein the object detection apparatus is mounted on a moving body.

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