JP2011164082A - Laser radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser radar device that improves accuracy of detecting a detection object. <P>SOLUTION: When such a detection state that a light receiving waveform detected at a predetermined turning angle is considered to meet a waveform detected at the previous same turning angle, is detected continuously, the light receiving waveform is set as a background waveform of that turning angle. When those two waveforms in which a detection time Tf of the light receiving waveform on the far distance side corresponds to a detection time To of the background waveform at the turning angle are detected, the length in the turning direction of the detection object detected depending on the light receiving waveform on the near distance side is operated and measured on the basis of the ratio of the light receiving waveform on the far distance side to the background waveform. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a laser radar device.

  Conventionally, a laser radar scanning device disclosed in Patent Document 1 is known as a technology related to a laser radar device that detects the distance and azimuth to a detection object using laser light. In this laser radar scanning device, when laser light is output from the laser diode, the laser light that has passed through the slit and passed through the optical isolator is converted into a substantially parallel light beam by the concave mirror and irradiated toward the space. When this laser light is reflected by the detection object and a part of the reflected light is again incident on the concave mirror, the reflected light is reflected by the concave mirror so as to be condensed toward the optical isolator, and the optical isolator Is reflected toward the photodiode. As a result, by outputting an electrical signal corresponding to the laser beam input by the photodiode, measuring the time from when the laser beam is output until the reflected light is detected, the distance to the detected object can be reduced. Looking for.

Japanese Patent No. 2789741

  By the way, although the laser beam emitted from the inside of the apparatus toward the outer space is converted into substantially parallel light, the diameter of the cross section perpendicular to the optical axis (hereinafter also referred to as laser spot diameter) is far. The distance spreads gradually as the distance increases. Therefore, even if the light emitting surface of the laser is set to a minimum, for example, the laser spot diameter may be about 20 to 30 cm after 30 m.

  Since the laser radar device detects only the amount of reflected light from the detection object, for example, from the first detection object and the second detection object having a larger size and a lower reflectance than the first detection object. When the amount of reflected light is equal, it is difficult to recognize the difference in size between the two. For this reason, there is a possibility that even an object of a size that is not originally required to be detected, for example, a small bird or a fallen leaf, may be detected.

  Further, when the reflected light from the surrounding detection object is detected by changing the emission direction of the laser light, the laser scanning interval becomes large for a remote detection object. Therefore, for example, when the emission timing of the laser beam is changed every 0.25 °, the laser scanning interval is about 13 cm at 30 m ahead, so even a small detection object has the same distance before and after the emission direction change. When the reflected light is detected, the size of the detected object is recognized as about 26 cm. As described above, there is a problem that an object having a size that is not originally required to be detected is detected due to an error due to the light emission timing (an error due to the angular resolution) and an error due to the spread of the laser spot diameter.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a laser radar device capable of improving the detection accuracy of a detection object.

  In order to achieve the above object, in the laser radar device according to claim 1, when the laser beam is generated from the laser beam generator and the laser beam generator, A light detecting means for detecting the reflected light reflected by the detection object as a waveform; and a deflecting means configured to be rotatable about a predetermined central axis. A rotating deflection unit for deflecting the reflected light toward the space and deflecting the reflected light toward the light detecting unit; a driving unit for driving the rotating deflection unit; and the laser beam generated by the laser beam generating unit. A distance measuring means for measuring a distance to the detection object based on a detection time from when the laser light is reflected by the detection object until the reflected light is detected by the light detection means; A detection state in which a waveform detected by the light detection means at a predetermined rotation angle is considered to coincide with a waveform detected at a previous same rotation angle. A setting means for setting the waveform as a background waveform of the rotation angle in the case, and two waveforms corresponding to the detection time of the background waveform at the rotation angle, the detection time of the waveform on the far side Measuring means for measuring the size of the detected object detected according to the waveform on the short distance side based on the ratio of the waveform on the long distance side and the background waveform when detected by the light detection means; It is characterized by providing.

  According to a second aspect of the present invention, in the laser radar device according to the first aspect, the measuring means is configured to perform the short-distance side based on a ratio between the amplitude value of the far-side waveform and the amplitude value of the background waveform. The size of the detected object detected according to the waveform is measured.

  According to a third aspect of the present invention, in the laser radar device according to the first aspect, the measurement means includes a time during which the far-side waveform is equal to or greater than a predetermined threshold and the background waveform is equal to or greater than the predetermined threshold. The size of the detected object detected according to the waveform on the short distance side is measured based on the ratio to the time of the state to be.

  According to a fourth aspect of the present invention, in the laser radar device according to any one of the first to third aspects, when the size of the detected object measured by the measuring means is outside the detection target, An invalidating means for invalidating the detection is provided.

  According to a fifth aspect of the present invention, in the laser radar device according to the fourth aspect, the size of the detection object to be detected is set according to the distance measured by the distance measuring means. To do.

  A sixth aspect of the present invention is the laser radar device according to any one of the first to fifth aspects, wherein the measuring means is a cross-sectional dimension of the laser light at a measurement distance to the detection object by the distance measuring means. The cross-sectional dimension calculating means for calculating the two-waveform is detected by the light detecting means at a first rotation angle by a part of the detection object, and the first rotation is detected by the remaining part of the detection object. When one waveform is detected by the light detection means at all rotation angles during a predetermined angle rotation from the angle, the number of rotation angles at which the one waveform is detected, and the two waveforms The length along the rotation direction of the detection object is measured based on the ratio and the cross-sectional dimension.

  A seventh aspect of the present invention is the laser radar device according to the sixth aspect, wherein the cross-sectional dimension calculating means calculates the cross-sectional dimension at the measurement distance in accordance with the spread of the laser beam.

  The invention according to claim 8 is the laser radar device according to any one of claims 1, 4 to 7, for determining whether or not a waveform detected by the light detection means exceeds a predetermined light amount. A plurality of threshold values are set, and in the coordinates where the light quantity is on the vertical axis and the time is on the horizontal axis, when the intersection where one of the threshold values intersects with the waveform detected by the light detection means is the intersection for area calculation, The measuring means includes a first far-side area that is an area of a polygonal region surrounded by a plurality of the area calculation intersections at which two or more of the plurality of thresholds intersect with the far-side waveform. And the first background side area, which is the area of a polygonal region surrounded by the plurality of area calculation intersections where the two or more threshold values intersect the background waveform, the short distance side Detected according to the waveform And measuring the magnitude of the serial detection object.

  According to a ninth aspect of the present invention, in the laser radar device according to the eighth aspect, the measuring means includes the two intersection points for area calculation at the minimum threshold value constituting the first far-side area, and the calculation of both the areas. A total area obtained by adding the area of a rectangular area surrounded by the vertical legs extending from the intersection point to the horizontal axis to the first long distance area, and the minimum threshold value constituting the first background area A total area obtained by adding the area of a quadrangular region surrounded by the two intersections for area calculation and the legs of the perpendicular line respectively drawn from the intersections for area calculation to the horizontal axis to the first background side area; Based on the ratio, the size of the detected object detected according to the waveform on the short distance side is measured.

  According to a tenth aspect of the present invention, in the laser radar device according to the eighth or ninth aspect, the distance between two intersections at which the waveform of the light quantity assumed to be detected by the light detection means and the threshold value intersect is determined for each light quantity. The distance is measured and stored in advance as a determination distance according to a threshold value, and the measurement unit performs the determination with the same threshold value and light amount as the distance between two intersection points where the predetermined threshold value intersects the waveform on the far side. The first far-side area and the first background-side area are calculated except for the area calculation intersection where the difference in distance from the work distance is larger than the distance difference at other threshold values. To do.

  According to an eleventh aspect of the present invention, in the laser radar device according to the tenth aspect, the measurement means has a predetermined threshold value and a light amount that is the same as the distance between two intersections where the predetermined threshold value intersects the waveform on the far side. When there is only one threshold value that is considered to match the determination distance, the first far-side area is defined as a line segment that connects the intersections at the one threshold value, and the one threshold value. Based on the area of a trapezoidal region having one of the two line segments as the upper base and the other as the lower base, and a line segment having the same light amount as the full length of the determination distance corresponding to another threshold value It is characterized by calculating.

  A twelfth aspect of the present invention is the laser radar device according to any one of the first to fourth aspects of the present invention, for determining whether or not the waveform detected by the light detection means exceeds a predetermined light amount. A plurality of threshold values are set, and in the coordinates where the light quantity is on the vertical axis and the time is on the horizontal axis, when the intersection where one of the threshold values intersects with the waveform detected by the light detection means is the intersection for area calculation, The measuring means includes a straight line connecting two near-distance sides of the four intersections for area calculation where two threshold values of the plurality of threshold values and the waveform on the long-distance side intersect, and two on the long-distance side. The two long-distance-side areas, which are the areas of a triangular region surrounded by two straight lines to be connected, and the horizontal axis, and the four intersections for area calculation where the two threshold values and the background waveform intersect A straight line connecting the two on the near distance side Waveform on the short distance side based on the ratio of the two straight lines connecting the two on the long distance side and the second background side area which is the area of the triangular area surrounded by the horizontal axis In other words, the size of the detected object detected in response to the measurement is measured.

  According to a thirteenth aspect of the present invention, in the laser radar device according to the twelfth aspect, the distance between two intersections where the waveform of the light amount assumed to be detected by the light detection means and the threshold value intersects with the threshold value for each light amount. Accordingly, the distance for determination is measured and stored in advance, and the measuring means includes the determination distance with the same threshold value and light amount as the distance between two intersections where the predetermined threshold intersects the waveform on the far side. The second far-side area and the second background-side area are calculated except for the area calculation intersection where the distance difference is larger than the distance difference at another threshold value.

  According to a fourteenth aspect of the present invention, in the laser radar device according to the thirteenth aspect, the measurement unit is configured to use a distance between two intersections where the predetermined threshold intersects the waveform on the far side, and the same threshold and light amount. When there is only one threshold that is considered to match the determination distance, the second far side area is defined as the first line segment connecting the intersections at the one threshold, A second line segment that has the same light amount as the threshold value and has the determination distance corresponding to the other threshold value as a full length, and the first line segment and the vertical bisector line coincide with each other. The calculation is based on the area of an isosceles triangle that passes through the end point and has the horizontal axis as the base.

  In the first aspect of the invention, when the detection state that the waveform detected by the light detection means at the predetermined rotation angle is considered to coincide with the waveform detected at the same previous rotation angle is continuously detected, This waveform is set as a background waveform of the rotation angle by the setting means. Then, when two waveforms corresponding to the detection time of the waveform on the far side corresponding to the detection time of the background waveform at the rotation angle are detected by the light detection means, the ratio between the waveform on the far side and the background waveform Based on the above, the size of the detected object detected according to the waveform on the short distance side is measured by the measuring means.

  If a detection state in which the waveform detected by the light detection means at a predetermined rotation angle is considered to coincide with the waveform detected at the previous same rotation angle is continuously detected, this waveform is always in its place. It can be estimated that this is due to reflected light from an object such as a wall (hereinafter also simply referred to as background). In the case where two waveforms are detected, a part of the emitted laser light is reflected by the detection object and detected as a near-field waveform, and then the remainder of the laser light is behind the emission direction. This is a case where the light is reflected by an object and detected as a waveform on the far side.

Therefore, when two waveforms are detected, if the detection time of the waveform on the far side corresponds to the detection time of the background waveform at the rotation angle, a part of the emitted laser light is detected It is estimated that the remainder is reflected by the background at a distance farther than the detected object. In this case, as the area occupied by the detection object on the short distance side in the cross section (hereinafter also referred to as spot cross section) perpendicular to the optical axis of the laser beam decreases, that is, as the detection object decreases, the waveform on the long distance side It changes so as to approach the waveform. For this reason, the size of the detected object detected according to the waveform on the short distance side can be measured based on the ratio between the waveform on the long distance side and the background waveform.
Accordingly, since the size of the detection object smaller than the spot cross section can be measured, the detection accuracy of the detection object can be increased.

  According to the second aspect of the present invention, the size of the detected object detected according to the near-field waveform is measured by the measuring unit based on the ratio between the far-field waveform amplitude value and the background waveform amplitude value. Is done. Thus, by calculating the area ratio of the detected object to the spot cross section based on the ratio of the amplitude values of both waveforms, the size of the detected object can be easily measured.

  In the invention of claim 3, the measuring means is used to measure the distance on the short distance side based on the ratio between the time when the waveform on the long distance side is equal to or greater than a predetermined threshold and the time when the background waveform is equal to or greater than the predetermined threshold. The size of the detected object detected according to the waveform is measured.

  As the area occupied by the detected object in the spot cross section becomes smaller, the time during which the far-side waveform is greater than or equal to the predetermined threshold changes so as to approach the time during which the background waveform is greater than or equal to the predetermined threshold. Therefore, the area ratio of the detected object to the spot cross section is calculated based on the ratio between the time when the far-side waveform is above the predetermined threshold and the time when the background waveform is above the predetermined threshold. By doing so, the size of the detected object can be easily measured.

  In the invention of claim 4, when the size of the detected object measured by the measuring means is outside the detection target, the detection of the detected object is invalidated by the invalid means. Can be prevented.

  In the invention of claim 5, since the size of the detection object to be detected is set according to the distance measured by the distance measuring means, for example, the size of the detection target at a long distance is set to be smaller than the short distance. By setting a large value, it is possible to detect a detection object having a desired size and reliably prevent detection of an object having a size that does not require detection.

  In the sixth aspect of the present invention, two waveforms are detected at the first rotation angle by a part of the detection object, and all of the waveforms during the predetermined rotation from the first rotation angle by the remaining part of the detection object are detected. When one waveform is detected at the rotation angle, the rotation of the detected object is determined based on the number of rotation angles at which one waveform is detected, the ratio of the two waveforms, and the cross-sectional dimension of the laser beam. A length along the moving direction (hereinafter, also referred to as a rotational direction length) is measured.

  When the rotation direction length of the detection object is sufficiently longer than the rotation direction length of the spot cross section, the center of the rotation direction of the detection object (hereinafter also referred to as all irradiation section) is the spot cross section at the rotation angle. All is irradiated. In addition, at the rotation direction end of the detection object (hereinafter also referred to as “partial irradiation unit”), a part of the spot cross section at the rotation angle is irradiated and the remaining part, except when the entire spot cross section is irradiated. Is irradiated on the background. Therefore, at the rotation angle corresponding to all irradiation parts, one waveform is detected at substantially the same detection time without detecting the background waveform, and at the rotation angle corresponding to a part of the irradiation part, Thus, two waveforms are detected.

  For this reason, the length of the rotation direction occupied by all the irradiation parts in the detected object is obtained from the number of rotation angles (the number of all irradiation parts) from which one waveform is detected. Further, the rotation direction length occupied by the partial irradiation portion of the detected object is obtained from the area ratio of the partial irradiation portion calculated from the ratio of the two waveforms to the spot cross section and the cross sectional dimension of the spot cross section. It is done. As a result, the rotational direction length of the detection object can be accurately measured based on the rotational direction length occupied by all the irradiation units and the rotational direction length occupied by the partial irradiation units.

  In the invention of claim 7, the cross-sectional dimension calculating means calculates the cross-sectional dimension of the spot cross section at the measurement distance in accordance with the spread of the laser beam. The cross-sectional dimension of the spot cross section can be easily calculated.

  In the invention of claim 8, the first area is an area of a polygonal region surrounded by a plurality of intersection points for area calculation where two or more of the plurality of threshold values and the waveform on the far side intersect by the measuring means. Based on the ratio between the long-distance area and the first background-side area, which is the area of a polygonal area surrounded by a plurality of area calculation intersections where the two or more threshold values and the background waveform intersect, the short distance The size of the detected object detected according to the waveform on the side is measured.

  The polygonal area surrounded by the intersections for area calculation as described above is an area reflecting the shape of the corresponding waveform. In particular, the larger the number of area calculation intersections, that is, the greater the number of thresholds, the more the corresponding waveform shape is reflected as the region. Therefore, by calculating the area of each region as the first long-distance side area and the first background-side area and using the ratio of these two areas, the ratio of the long-distance side waveform and the background waveform can be accurately calculated, The measurement accuracy of the size of the detected object can be improved.

  In the invention of claim 9, by the measuring means, the two intersections for area calculation at the minimum threshold value constituting the first far-side area and the legs of the perpendicular line respectively dropped from the intersections for area calculation to the horizontal axis. From the total area obtained by adding the area of the enclosed rectangular area to the first far-side area, two area calculation intersections at the minimum threshold value constituting the first background-side area, and these two area calculation intersections Detected according to the waveform on the near distance side based on the ratio of the area of the quadrangular region surrounded by the legs of the perpendicular line respectively drawn on the horizontal axis to the total area of the first background side area The size of the detected object is measured.

  In the invention according to claim 8, since the ratio of the total area obtained by further adding the area of the quadrangular region surrounded by the two intersection points for area calculation with the minimum threshold and the leg of the perpendicular line is used, the polygonal shape The area obtained by adding the rectangular area to this area is an area reflecting the shape of the corresponding waveform more than the polygonal area alone. For this reason, by using the ratio of the respective total areas, the ratio between the waveform on the far side and the background waveform can be calculated with higher accuracy, and the measurement accuracy of the size of the detected object can be further improved.

  In the invention of claim 10, the measurement means uses a distance difference between two intersections at which the predetermined threshold intersects the waveform on the long distance side and a determination distance with the same threshold and light amount as other thresholds. The first far-side area and the first background-side area are calculated except for the intersection for area calculation that becomes larger than the distance difference between the first distance side area and the first background side area.

  In the case of a normal light reception waveform, it is assumed that the distance between two intersections where the light reception waveform intersects with a predetermined threshold value is substantially constant with the same threshold value and light amount. That is, it is assumed that the area calculation intersection where the distance difference from the determination distance is larger than the distance difference at other thresholds is likely to be an intersection between the abnormal component included in the received light waveform and the threshold. The For this reason, by calculating the first long-distance side area and the first background-side area excluding the area calculation intersection as described above, the ratio of the long-distance side waveform and the background waveform can be calculated more accurately. Therefore, the measurement accuracy of the size of the detected object can be improved with certainty.

  In the invention of claim 11, when the distance between two intersections where the predetermined threshold intersects the waveform on the far side and the determination threshold with the same threshold and the same amount of light are considered to be equal to each other, The first distant side area by the measuring means is a line segment connecting the intersections at the one threshold value, and a determination distance corresponding to another threshold value with the same light amount as the light amount at the one threshold value. The calculation is based on the area of the trapezoidal region having one of the two line segments as the upper base and the other as the lower base.

  If the waveform on the far side is disturbed due to the influence of noise or the like, even if multiple thresholds are set, the distance between two intersections where the predetermined threshold crosses the waveform on the far side is the same threshold and light amount. There is only one threshold that is considered to match the determination distance, and there may be a large difference in distance from the determination distance for other threshold values. In this case, a polygonal region in which the shape of the waveform on the far side is reflected cannot be assumed with only two intersection points for area calculation.

  Therefore, the distance between intersections at the other threshold is estimated from the distance for determination corresponding to the other threshold, with the distance between the intersections at one threshold considered to be the same as the determination distance. Then, one of the two line segments of the line segment having the total distance between the intersection points estimated in this way and the line segment connecting the intersection points at the one threshold value as the reference is the upper base, and the other is the lower base. The first far-side area is calculated based on the trapezoidal area. Thus, by estimating the distance between the intersections at other threshold values, the first far-side area can be calculated even when the far-side waveform is disturbed due to the influence of noise or the like.

  In a twelfth aspect of the present invention, the measuring means causes the straight line connecting the two near-field sides and the long-distance side among the four area calculation intersections where the two threshold values of the plurality of threshold values and the waveform on the long-distance side intersect. The two long-distance-side areas, which are the areas of the triangular region surrounded by the two straight lines connecting the two, and the horizontal axis, and four area calculation intersections where the two threshold values and the background waveform intersect Of these, the ratio between the two straight lines connecting the two on the short distance side and the straight line connecting the two on the long distance side and the second background side area which is the area of the triangular area surrounded by the horizontal axis Based on this, the size of the detected object detected according to the waveform on the short distance side is measured.

  The triangular area as described above is an area reflecting the shape of the corresponding waveform. In particular, only by setting at least two threshold values, a region reflecting the corresponding waveform shape is partitioned. For this reason, the area of each region is calculated as the second long-distance side area and the second background-side area, and by using the ratio of these two areas, the ratio of the long-distance side waveform and the background waveform can be accurately calculated, The measurement accuracy of the size of the detected object can be improved.

  In the invention of claim 13, in the measurement means, the difference between the predetermined threshold and the distance for determination with the same amount of light as the distance between two intersections intersecting the waveform on the far side is the other threshold. The second far-side area and the second background-side area are calculated except for the area calculation intersection that is larger than the distance difference.

  In the case of a normal light receiving waveform, it is assumed that the distance between two intersections where the waveform intersects with a predetermined threshold value is substantially constant with the same threshold value and light amount. That is, it is assumed that the area calculation intersection where the distance difference from the determination distance is larger than the distance difference at other thresholds is likely to be an intersection between the abnormal component included in the received light waveform and the threshold. The For this reason, by calculating the second long-distance side area and the second background-side area except for the area calculation intersection as described above, the ratio between the long-distance side waveform and the background waveform can be calculated more accurately. Therefore, the measurement accuracy of the size of the detected object can be improved with certainty.

  In the invention of claim 14, when the distance between two intersections where the predetermined threshold intersects the waveform on the far side and the determination threshold with the same threshold and the same amount of light are considered to be equal to each other, According to the measurement means, the second long-distance side area corresponds to the first line segment connecting the intersections at the one threshold value and the same light quantity as the one threshold value and the other one threshold value. An area composed of an isosceles triangle that passes through both end points of the first line segment and the second line segment whose vertical bisector line coincides with the determination distance as a full length. Calculated based on area.

  If the waveform on the far side is disturbed due to the influence of noise or the like, even if multiple thresholds are set, the distance between two intersections where the predetermined threshold crosses the waveform on the far side is the same threshold and light amount. There is only one threshold that is considered to match the determination distance, and there may be a large difference in distance from the determination distance for other threshold values. In this case, it is not possible to assume a triangular area in which the shape of the waveform on the long-distance side is reflected only with the two intersection points for area calculation.

  Therefore, the distance between intersections at the other threshold is estimated from the distance for determination corresponding to the other threshold, with the distance between the intersections at one threshold considered to be the same as the determination distance. At this time, an area composed of an isosceles triangle passing through the end points of both the first line segment and the second line segment and having the horizontal axis as the base is a region reflecting the shape of the corresponding waveform. The second far side area is calculated based on the area of the region. In this way, by estimating the distance between the intersections at other threshold values, the second far-side area can be calculated even when the far-side waveform is disturbed due to the influence of noise or the like.

1 is a cross-sectional view schematically illustrating a laser radar device according to a first embodiment. It is explanatory drawing for demonstrating the condition where two light reception waveforms are detected. FIG. 3A is a waveform diagram illustrating a state in which the detection object and the background are detected, and FIG. 3B is a waveform diagram illustrating a state in which only the background is detected. 6 is a part of a flowchart illustrating the flow of detection processing in the control circuit according to the first embodiment. 6 is a part of a flowchart illustrating the flow of detection processing in the control circuit according to the first embodiment. 6 is a part of a flowchart illustrating the flow of detection processing in the control circuit according to the first embodiment. FIGS. 7A to 7D are explanatory views illustrating regions where the laser beam is reflected by the detection object and regions where the laser beam is reflected by the background in each spot cross section. FIGS. 8A to 8C are explanatory views illustrating regions where the laser beam is reflected by the detection object and regions where the laser beam is reflected by the background in each spot cross section. FIGS. 9A and 9B are explanatory diagrams illustrating regions where the laser beam is reflected by the detection object and regions where the laser beam is reflected by the background in each spot cross section. It is a part of flowchart which illustrates the flow of the detection process in the control circuit which concerns on 2nd Embodiment. It is explanatory drawing for demonstrating a 1st long distance side area and a 1st background side area. It is explanatory drawing which shows an example of the light quantity-determination distance map which shows the relationship between a light quantity and the distance for determination for every threshold value. It is explanatory drawing which shows the intersection for area calculation where the waveform containing a noise etc. and a threshold value cross. It is explanatory drawing which shows the intersection for area calculation where the waveform which the other waveform overlapped, and the threshold value cross. It is explanatory drawing which illustrates the waveform which has no threshold value considered that the distance between intersections and the distance for determination correspond. It is explanatory drawing which illustrates the waveform which has no threshold value considered that the distance between intersections and the distance for determination correspond. It is a part of flowchart which illustrates the flow of the detection process in the control circuit which concerns on 3rd Embodiment. It is explanatory drawing for demonstrating a 2nd long distance side area and a 2nd background side area. It is explanatory drawing which shows the 1st line segment and the 2nd line segment in the state in which the waveform containing noise etc. and the threshold value cross.

[First Embodiment]
Hereinafter, a first embodiment in which the laser radar device of the present invention is embodied will be described with reference to the drawings.
As shown in FIG. 1, the laser radar device 1 includes a laser diode 10, a photodiode 20 that receives reflected light L3 from a detection object, and a control circuit 70 that controls the laser diode 10 and the photodiode 20. It is configured as a device that detects the distance and direction to a detection object. The laser diode 10 corresponds to an example of “laser light generation means”, and is supplied with a pulse current from a laser drive circuit (not shown) under the control of the control circuit 70 to project pulsed laser light (laser light L0). To do.

  The photodiode 20 corresponds to an example of “light detection means”, and when the laser light L0 is generated from the laser diode 10, the laser light L0 detects the reflected light L3 reflected by the detection object and receives the light. The signal is converted into a signal and output to the control circuit 70. In addition, about the reflected light from a detection object, the thing of a predetermined area | region is taken in, and in the example of FIG. 1, the reflected light of the area | region between two lines shown with the code | symbol L3 is taken in. .

  A lens 60 and a mirror 30 are provided on the optical axis of the laser beam L0. The lens 60 is configured as a collimating lens, and converts the laser light L0 from the laser diode 10 into substantially parallel light.

  The mirror 30 realizes the transmission of the laser light L0 from the laser diode 10 and the reflection of the reflected light L3 from the detection object side. Specifically, it has a reflection surface 31 that is inclined at a predetermined angle with respect to the optical axis of the laser beam L0, and a through path 32 that intersects the reflection surface 31. In this configuration, the optical axis of the laser light L0 and the optical axis of the reflected light L3 are made to coincide with each other, and the mirror 30 is arranged on the common optical axis and allows the laser light L0 to pass through the through path 32. On the other hand, the reflection surface 31 reflects the reflected light L3 toward the photodiode 20.

  As described above, the lens 60 for converting the laser light L0 into substantially parallel light is provided on the optical path of the laser light L0 from the laser diode 10 to the through path 32. It is preferable to generate substantially parallel light that allows almost all of the light to pass through at 32. Conversely, when paying attention to the through path 32, the through path 32 may be sized to pass almost all the light of the laser beam L 0 that has been made substantially parallel by the lens 60.

  A rotation deflection mechanism 40 is provided on the optical axis of the laser light L0 that passes through the mirror 30. The rotation deflection mechanism 40 is disposed so as to be rotatable about a central axis extending in the optical axis direction of the laser light L0, and the laser beam L0 is emitted by a concave mirror 41 whose focal position is set on the central axis. The light is reflected toward the space and the reflected light L3 is deflected toward the mirror. The rotation deflection mechanism 40 and the concave mirror 41 correspond to an example of “rotation deflection means” and “deflection means” recited in the claims.

  Further, a motor 50 that rotationally drives the rotation deflection mechanism 40 is provided. The motor 50 corresponds to an example of “driving means”, and is configured to rotate and drive a rotatable concave mirror 41 connected to the shaft 42 by rotating the shaft 42. Here, the motor 50 is constituted by a step motor. Various step motors can be used. If a step motor having a small angle for each step is used, precise rotation is possible. Further, driving means other than the step motor may be used as the motor 50. For example, a servo motor or the like may be used, or a pulsed laser beam may be output in synchronism with the timing when the concave mirror 41 faces the direction in which the distance measurement is desired, and a desired direction can be detected. Good. In the first embodiment, as shown in FIG. 1, a rotation angle sensor 52 that detects the rotation angle of the shaft 42 of the motor 50, that is, the rotation angle of the concave mirror 41, is provided. Then, an angle signal corresponding to the rotation angle of the concave mirror 41, that is, an angle signal corresponding to the laser beam emission direction is output to the control circuit 70. As the rotation angle sensor 52, various types such as a rotary encoder that can detect the rotation angle of the shaft 42 can be used, and the type of the motor 50 to be detected is not particularly limited. Applicable to various types.

  In the first embodiment, the laser diode 10, the photodiode 20, the mirror 30, the lens 60, the rotation deflection mechanism 40, the motor 50, the control circuit 70, and the like are accommodated in the case 3, and dust protection and impact protection are achieved. It has been. Around the concave mirror 41 in the case 3, a light guide portion 4 is formed so as to allow the laser light L 0 and the reflected light L 3 to pass therethrough so as to surround the concave mirror 41. The light guide 4 is formed in an annular shape centering on the optical axis of the laser light L0 incident on the concave mirror 41, and is formed over approximately 360 °. The window part 5 which consists of a permeable glass plate etc. is arranged, and dust prevention is achieved.

  The window portion 5 is configured to be inclined over the entire circumference with respect to a virtual plane orthogonal to the optical axis of the laser beam L0 entering the concave mirror 41. In other words, the plate surface is inclined with respect to the laser beam L0 from the concave mirror 41 toward the space. Therefore, even if the laser beam L0 traveling from the concave mirror 41 toward the space is reflected by the window portion 5, it is difficult to become noise light.

  The control circuit 70 is composed of, for example, a microcomputer and a memory (ROM, RAM, EEPROM, etc.), and detects the distance and direction to the detection object by controlling the laser diode 10 and the photodiode 20 described above. It has a function to execute the detection process to be executed by a predetermined computer program.

  Next, the detection process in the control circuit 70 of the laser radar apparatus 1 according to the first embodiment will be described. In this detection process, in order to detect a detection object having a size to be detected, a length along the rotation direction of the detection object (hereinafter referred to as the rotation direction length) is based on the light reception signal input from the photodiode 20. Is also measured). First, this measurement method will be described with reference to FIGS.

  In order to detect the distance and direction to the detection object, when the concave mirror 41 is rotated by a predetermined angle by the rotational drive of the motor 50 and the emission direction of the laser light is changed by the predetermined angle, the angle signal from the rotation angle sensor 52 is changed. The received light signal is input from the photodiode 20 to the control circuit 70 at every rotation angle of the concave mirror 41 (hereinafter, also simply referred to as a rotation angle). Here, when a detection state in which a light reception waveform detected by a light reception signal input at a predetermined rotation angle is considered to coincide with a light reception waveform detected at the same previous rotation angle is continuously detected, It can be estimated that the received light waveform (hereinafter also referred to as background waveform) is due to reflected light from an object such as a wall (hereinafter also referred to as background) that is always located at that location.

  In addition, as illustrated in FIG. 2, when a part L0a of the emitted laser light is reflected by the detection object Sa and the remaining part L0b of the laser light is reflected by the background Sb behind the emission direction, As illustrated in FIG. 3A, the light reception signal includes two light reception waveforms. Therefore, as illustrated in FIGS. 3A and 3B, when two received light waveforms are detected, the detection time Tf of the far-field received light waveform becomes the detection time To of the background waveform at the rotation angle. In a corresponding case, it is estimated that a part of the emitted laser light is reflected by the detection object and the remaining part is reflected by the background at a distance farther than the detection object. In this case, the detection object on the short distance side (detection time Tn) occupies the cross section orthogonal to the optical axis of the laser beam (hereinafter also referred to as spot cross section), that is, the detection object becomes smaller, the smaller the detection object, The received light waveform changes so as to approach the background waveform. Therefore, based on the ratio between the amplitude value Hf of the light receiving waveform on the long distance side and the amplitude value Ho of the background waveform, the size of the detected object (length in the rotation direction) detected according to the light receiving waveform on the short distance side ) Can be measured. In FIG. 2, for convenience of explanation, the laser beams L0a, L0b, etc. are shown enlarged.

Hereinafter, a specific flow of the detection process will be described with reference to the flowcharts of FIGS.
First, in step S101 of FIG. 4, a laser emission process is performed. In this process, a light emission signal having a predetermined pulse width corresponding to the light emission trigger generated by the timing signal generator is output to the laser drive circuit. As a result, the laser driving circuit controls the driving, and the laser diode 10 outputs a pulsed laser beam (laser beam L0) at a time interval corresponding to the predetermined pulse width. The laser light L0 is projected as diffused light having a certain spread angle, and is converted into substantially parallel light by passing through the lens 60. The laser light L0 that has passed through the lens 60 passes through the through path 32 formed in the mirror 30, enters the concave mirror 41, is reflected as substantially parallel light by the concave mirror 41, and is irradiated toward the space.

  Next, in step S103, a laser light receiving process is performed. When the laser light L0 is reflected as reflected light by a detection object or the like, the reflected light is collected by the concave mirror 41 and reflected toward the photodiode 20 via the mirror 30. Thus, in the laser light receiving process, a light reception signal corresponding to the reception of the reflected light is input from the photodiode 20 to the control circuit 70.

  Subsequently, a storage process is performed in step S105, and a light reception signal from the photodiode 20 is stored in a memory or the like together with the rotation angle. In step S107, based on the angle signal input from the rotation angle sensor 52, it is determined whether or not the emission direction of the laser light has made one round. If the laser light emission direction does not go around (No in S107), a rotation process is performed in Step S109, and the motor 50 is driven to rotate by one step. As a result, the concave mirror 41 rotates by a unit angle, and the laser beam emission direction changes by a unit angle. And the process from said step S101 is repeated until the emission direction of a laser beam makes one round.

  Then, when the laser light emission direction makes a round and each light reception signal for this round is stored in a memory or the like (Yes in S107), a light reception signal extraction process is performed in step S111. In this process, each received light signal from the reference rotation angle to the rotation angle that makes a round is extracted one by one every time the process is performed.

  Next, in step S113, it is determined whether or not a light reception waveform is included in the light reception signal at the extracted rotation angle. Here, if the received light signal does not exceed the predetermined threshold value, the received light waveform is not included (No in S113), and in step S115, one step of the motor 50 is performed with respect to the rotation angle extracted at the current stage. It is determined whether or not the received light signal at the rotation angle in the reverse rotation direction (hereinafter also referred to as the pre-extraction rotation angle) includes a light reception waveform different from the background waveform. If the light reception signal at the pre-extraction rotation angle does not include a light reception waveform different from the background waveform (No in S115), it is determined in step S117 whether or not all light reception signals have been extracted in one round. Until all the received light signals are extracted, it is determined No and the processing from step S111 is repeated.

  Here, if it is determined in step S113 that the received light signal at the extracted rotation angle is equal to or greater than a predetermined threshold value, the received light signal includes a received light waveform (Yes in S113), step S119 in FIG. It is determined whether or not there is only one light reception waveform included in the light reception signal. Then, since only the reflected light from the detection object or the background is received, when there is only one light reception waveform included in the light reception signal, it is determined Yes in S119.

  Subsequently, in step S121, it is determined whether or not this light reception waveform is considered to coincide with the light reception waveform detected at the previous same rotation angle. Here, when the detection time and amplitude value of the received light waveform are different from the previous ones and it is not considered that the two waveforms match, it is determined that the reflected light from the detected object has been detected, and No is determined in step S121. . When the detection time storage process is performed in step S123 and the detection time of the received light waveform is stored in the memory together with the rotation angle, the determination process in step S117 is performed.

  On the other hand, if it is determined in step S121 that the light reception waveform matches the light reception waveform detected at the previous rotation angle (Yes in S121), whether or not the light reception waveform is a background waveform in step S125. Is determined. Here, if the extracted received light waveform continues to be regarded as being coincident with the previously detected light received waveform at the rotation angle, the background waveform is determined as Yes in step S125. In step S127, a background waveform setting process is performed, and the extracted received light waveform is set as a background waveform and stored in the memory. If the background waveform is set in this way or if it is determined No in step S125, the determination process in step S115 is performed. In the background waveform setting process, the waveform at the current stage is set as a new background waveform. However, the present invention is not limited to this. For example, a new waveform is obtained by averaging the waveform at the current stage and the background waveform before the previous time. A simple background waveform may be set. Further, the control circuit 70 that executes step S127 may correspond to an example of a “setting unit” described in the claims.

  In the above-described step S119, when there are two light receiving waveforms included in the light receiving signal, a part of the emitted laser light is reflected by the detection object as illustrated in FIG. The case of being reflected by the object is estimated and determined as No. In step S129, it is determined whether or not the far-side received light waveform among the received light waveforms is the background waveform. Here, as illustrated in FIG. 3A, when the detection time Tf of the light reception waveform on the long distance side corresponds to the detection time To of the background waveform at the rotation angle (Yes in S129), the above-described operation is performed. Thus, it can be estimated that the light reception waveform on the short distance side is due to the reflected light from the detection object. In this case, when the detection time storage process is performed in step S131 and the detection time Tn on the short distance side in the light reception waveform is stored in the memory together with the rotation angle, the determination process in step S117 is performed. On the other hand, if the far side of the two received light waveforms included in the received light signal is not estimated as the background waveform, it is determined No in step S129, and the determination process in step S117 is performed.

  As described above, when the reflected light from the detection object is received before the light reception signal for the entire round is extracted, the detection time of the light reception waveform corresponding to the reception of the reflected light in step S123 or step S131. Is stored in the memory together with the rotation angle.

  In addition, when the received light signal at the previous extraction rotation angle includes a light reception waveform different from the background waveform in step S115 described above, only the previous extraction rotation angle or the reverse rotation from the previous extraction rotation angle is performed. It is estimated that the reflected light from the detection object is received within an angular range rotated by a predetermined angle in the direction. In this case, Yes is determined in step S115, and in step S133 of FIG. 6, the rotation angle at which the two received light waveforms are included in the received light signal other than both ends in the rotation direction in the waveform detection rotation angle range. It is determined whether or not there is. Here, the waveform detection rotation angle range is a rotation in which light reception waveforms having substantially the same detection time are detected at all rotation angles during a predetermined angle rotation from the previous extraction rotation angle in the reverse rotation direction. It is set as a range of angles.

  At this waveform detection rotation angle, when there is no rotation angle in which the light reception signal includes two light reception waveforms except at both ends in the rotation direction (No in S133), the reflected light from one detection object is received. As described below, the rotation direction length X of the detected object is calculated and measured by the first rotation direction length measurement process in step S135 as follows. The control circuit 70 that executes step S135 and step S141 to be described later can correspond to an example of “distance measuring means”, “measuring means”, and “cross-sectional dimension calculating means” recited in the claims.

  Here, the calculation method of the rotation direction length X of the detection object will be described with reference to FIGS. 7 and 8. 7 and 8 and FIG. 9 described later, the spot cross section of the laser beam is illustrated as a square area for each rotation angle, and the hatched area in the square area is the detected object in the spot cross section. A region where the laser beam is reflected is illustrated, and a hatched region is a region where the laser beam is reflected in the background. It should be noted that this hatched area includes an area where nothing is reflected except when two received light waveforms are detected. 7 to 9, the spot cross section at the current rotation angle is indicated by Ln, the spot cross section at the previous extraction rotation angle is Ln−1, and in the reverse rotation direction from the previous extraction rotation angle. The spot cross sections at the unit rotation angle are indicated by Ln-2, Ln-3... Ln-k.

  First, since the size of the detected object is smaller than the spot cross section, when only a part of the spot cross section Ln-1 is reflected by the detected object as illustrated in FIG. Two light reception waveforms are detected by the angle, and the light reception waveform by the detection object is not detected at the rotation angle in the reverse rotation direction by one step of the motor 50 from the pre-extraction rotation angle.

  In this case, in step S135, detection is performed according to the light reception waveform on the short distance side based on the ratio between the amplitude value Hf of the light reception waveform on the long distance side and the amplitude value Ho of the background waveform at the pre-extraction rotation angle. The area ratio of the detected object to the spot cross section Ln-1 is calculated (see FIG. 3). Next, the distance to the detected object is calculated based on the detection time Tn of the light reception waveform on the short distance side. Subsequently, the dimension (laser spot diameter) of the spot cross section at this calculation distance is calculated. The calculation of the cross-sectional dimension is performed based on the calculated distance using a map or the like in which the relationship between the calculation distance and the cross-sectional dimension is set in advance in consideration of the spread of the laser beam. The rotation direction length X of the detection object is calculated based on the calculated cross-sectional dimension and area ratio. For example, when the distance to the detection object is calculated as 30 m based on the detection time Tn and the spot cross-sectional dimension at this distance is calculated as 20 cm × 20 cm based on the above map, the amplitude value Hf of the light reception waveform on the far side is calculated. Is 40% with respect to the amplitude value Ho of the background waveform, the rotation direction length of the detected object is calculated as X = 8 cm.

  Further, since the difference between the size of the detected object and the size of the spot cross section is small, only a part of the spot cross sections Ln−1 and Ln−2 is reflected by the detected object as illustrated in FIG. 7B. In this case, the two light receiving waveforms are respectively detected at the rotation angle in the reverse rotation direction by one step of the motor 50 from the previous extraction rotation angle and from the previous extraction rotation angle. However, the received light waveform by the detection object is not detected at the rotation angle in the reverse rotation direction by two steps of the motor 50.

  In this case, in step S135, detection is performed in accordance with the light reception waveform on the short distance side based on the ratio between the amplitude value Hf of the light reception waveform on the long distance side and the amplitude value Ho of the background waveform at the both rotation angles. The area ratio of the detected object to the spot cross-sections Ln-1 and Ln-2 is calculated. Next, the distance to the detection object and the size of the spot cross section at this calculation distance are calculated based on the detection time Tn of the light reception waveform on the short distance side. The rotation direction length X of the detection object is calculated based on the calculated cross-sectional dimension and area ratio. For example, when the distance to the detection object is calculated as 30 m based on the detection time Tn and the size of the spot cross section at this distance is calculated as 20 cm × 20 cm according to the map, If the amplitude value of the received light waveform is 60% and 30% of the amplitude value of the background waveform, the length of the detected object in the rotation direction is calculated as X = 12 + 6 = 18 cm.

  When the size of the detection object is sufficiently larger than the spot cross section, a part of the spot cross sections Ln−1 and Ln−k are end portions in the rotation direction of the detection object as illustrated in FIG. (Hereinafter also referred to as “partially irradiated part”), and all of the spot cross-sections Ln−2,... Ln−k + 1 are reflected by the center part in the rotation direction of the detection object (hereinafter also referred to as “all irradiated part”). The For this reason, two light reception waveforms are detected at both rotation angles corresponding to a part of the irradiation unit, and one waveform is detected without detecting a background waveform at the rotation angles corresponding to all irradiation units. It will be.

  In this case, in step S135, at both rotation angles corresponding to the partial irradiating unit, based on the ratio of the amplitude value Hf of the received light waveform on the far side and the amplitude value Ho of the background waveform, The area ratio of the detected object detected in accordance with the received light waveform to the spot cross-sections Ln−1 and Ln−k is calculated. Next, the distance to the detection object and the size of the spot cross section at this calculation distance are calculated based on the detection time Tn of the light reception waveform on the short distance side. The rotation direction length X of the detection object is calculated based on the cross-sectional dimensions and area ratio calculated in this way and the number of rotation angles corresponding to all irradiation parts. For example, when the distance to the detection object is calculated as 30 m based on the detection time Tn and the spot cross-sectional dimension at this distance is calculated as 20 cm × 20 cm based on the map, both rotations corresponding to a part of the irradiation unit The amplitude value Hf of the light receiving waveform on the far side in terms of angle is 60% and 30% with respect to the amplitude value Ho of the background waveform, and the number of rotation angles corresponding to all irradiation parts is two (k = 4) In this case, the length of the detected object in the rotation direction is calculated as X = 12 + 20 + 20 + 6 = 58 cm.

  As described above, when the rotation direction length X of the detected object is calculated in step S135, it is determined in step S137 whether or not the rotation direction length X is greater than or equal to a predetermined threshold value Xo. Note that the predetermined threshold value Xo is the minimum length in the rotation direction of the object to be detected, and for example, the size of the detection target at a long distance is made larger than the short distance according to the measured distance. Specifically, when the distance to the detection object is 30 m, it is set to 10 cm.

  Here, when the rotation direction length X of the detected object is calculated as 18 cm as exemplified in FIG. 7B, for example, it is determined Yes in step S137 and output in step S139. Processing is performed, and the distance, rotation angle (emission direction), rotation direction length X, and the like related to the detected object are output to a predetermined external device or the like. Then, the determination process in step S117 is performed.

  On the other hand, when the rotation direction length X of the detected object is calculated as 8 cm as illustrated in FIG. 7A, for example, it is determined No in step S137, and the output process in step S139 is performed. Without being made, the determination process in step S117 is performed. That is, a detection object having a rotation direction length X that is less than a predetermined threshold value Xo is invalid because it is an object having a size that does not require detection.

  Thus, in the first embodiment, it is possible to measure the rotational direction length X of the detection object that is smaller than the spot cross section. Conventionally, the size of the detection object (length in the rotation direction) is measured based on the presence or absence of reflected light for each spot cross section. That is, in the example of FIG. 7A, the rotation direction length X of the detection object is measured as 20 cm based on the spot cross-sectional dimension at the measurement distance by only receiving the reflected light at one rotation angle. In the example of FIG. 7B, only 40 cm is measured when the reflected light is received at two rotation angles. For this reason, in the first embodiment, the rotational direction length X of the detection object smaller than the spot cross section, which is impossible to measure with the prior art, can be measured with high accuracy.

  Further, as illustrated in FIG. 7D, a part of the spot cross-section Ln-1 is reflected by a detection unnecessary object having a size unnecessary for detection such as a fallen leaf with respect to FIG. Conventionally, when the light is reflected, the reflected light from the spot cross section is received, and the size of the spot cross section is added to the size of the detection object (the length in the rotation direction). In the first embodiment, only the area ratio of the detection unnecessary object in the spot cross section is added to the size (rotation direction length) of the detection object. An error related to the calculation of the length X can be reduced.

  If there is a rotation angle in which the two light receiving waveforms are included in the received light signal except at both ends in the rotation direction in the waveform detection rotation angle range in the above-described step S133 (Yes in S133), the first in step S141. 2. A length measurement process in the rotational direction is performed. In this process, for example, as illustrated in any of FIGS. 8A to 8C, in addition to the spot cross sections Ln-1 and Ln-5 at both ends in the rotational direction, the spot cross section Ln-3 is used. The rotation direction length X is measured in a state where a plurality of patterns are assumed when two light reception waveforms are detected.

  As described above, when two received light waveforms are detected at the spot cross section Ln-3, a part of the spot cross section Ln-3 is partially irradiated by the two detection objects as illustrated in FIG. A state in which each of the spots is reflected, a state in which a part of the spot cross section Ln-3 is reflected only by one of the two irradiation parts of the two detection objects as illustrated in FIG. 8B, and FIG. ), It is not possible to determine which state is a state in which a part of the spot cross section Ln-3 is reflected by a detection object existing between two detection objects.

  Therefore, in the first embodiment, in the case of the detection state, assuming that two detection objects are detected, the rotation direction length X of each detection object is calculated. Specifically, the half of the rotation direction length obtained from the above-mentioned area ratio in the spot section Ln-3 is the rotation direction length corresponding to the spot sections Ln-1 and Ln-2 and the spot section Ln-4. , Ln-5, and the corresponding rotation direction length X, the rotation direction lengths X of the two detection objects are respectively calculated. If the calculated rotation direction length X is equal to or greater than the predetermined threshold value Xo (Yes in S137), the distance related to the detected object corresponding to the rotation direction length X in step S139, The rotation angle (emission direction), the rotation direction length X, and the like are output to the external device or the like.

  As described above, in the laser radar device 1 according to the first embodiment, the detection state in which the received light waveform detected at the predetermined rotation angle is considered to coincide with the waveform detected at the previous same rotation angle. When detected continuously, this received light waveform is set as the background waveform of the rotation angle. When two waveforms are detected in which the detection time Tf of the received light waveform on the far side corresponds to the detection time To of the background waveform at the rotation angle, the ratio between the received light waveform on the far side and the background waveform is detected. Based on the above, the rotation direction length (size) of the detected object detected according to the light reception waveform on the short distance side is calculated and measured.

  Thus, since the size of the detected object detected according to the waveform on the short distance side is measured based on the ratio between the light reception waveform on the long distance side and the background waveform, the detection object smaller than the spot cross section is measured. Since the size can be measured, the detection accuracy of the detection object can be increased.

  Further, in the laser radar device 1 according to the first embodiment, detection is performed according to the near-field waveform based on the ratio between the far-field received light waveform amplitude value Hf and the background waveform amplitude value Ho. The size of the detected object is measured. Thus, the size of the detected object can be easily measured by calculating the area ratio of the detected object to the spot cross section based on the ratio between the amplitude value Hf of the light receiving waveform on the far side and the amplitude value Ho of the background waveform. can do.

  Furthermore, in the laser radar device 1 according to the first embodiment, when the size of the measured detection object is outside the detection target, the detection of the detection object becomes invalid, and thus an object having a size that does not require detection. Can be prevented.

  Furthermore, in the laser radar device 1 according to the first embodiment, since the size of the detection object to be detected is set according to the measured distance, the detection target at a long distance as described above. By setting the size to be larger than the short distance, it is possible to detect a detection object having a desired size and reliably prevent detection of an object having a size that does not require detection.

  Further, in the laser radar device 1 according to the first embodiment, two waveforms are detected by the partial irradiation unit of the detection object, and all the rotations during the rotation by a predetermined angle from the pre-extraction rotation angle by the entire irradiation unit are performed. When one waveform is detected at the moving angle, the rotation of the detected object is based on the number of rotation angles at which one waveform is detected, the ratio of the two waveforms, and the cross-sectional dimension of the laser beam. The direction length X is measured. As described above, the rotation direction length X of the detection object can be accurately measured by calculating the rotation direction length of the entire irradiation unit and the rotation direction length of the partial irradiation unit among the detection objects. it can.

  Furthermore, in the laser radar device 1 according to the first embodiment, since the cross-sectional dimension of the spot cross section at the measurement distance is calculated according to the spread of the laser light, the measurement distance is obtained by grasping the spread of the laser light in advance. The cross-sectional dimension of the spot cross section at can be easily calculated.

[Second Embodiment]
Hereinafter, a second embodiment of the laser radar device of the present invention will be described with reference to the drawings. FIG. 10 is a part of a flowchart illustrating the flow of detection processing in the control circuit 70 according to the second embodiment. FIG. 11 is an explanatory diagram for explaining the first far-side area and the first background-side area. FIG. 12 is an explanatory diagram illustrating an example of a light amount-determination distance map that shows the relationship between the light amount and the determination distance Y for each threshold value. FIG. 13 is an explanatory diagram showing an area calculation intersection point P where a waveform including noise and the threshold intersect. FIG. 14 is an explanatory diagram showing an area calculation intersection point P where a threshold value and a waveform in which other waveforms overlap each other. FIG. 15 and FIG. 16 are explanatory diagrams illustrating waveforms in which there is no threshold value that the distance between intersections and the determination distance Y are considered to match.

  In the laser radar apparatus 1 according to the second embodiment, the flowchart shown in FIG. 10 is adopted instead of the flowchart shown in FIG. 6 in order to change the calculation method of the rotation direction length X of the detected object. However, it is different from the laser radar device according to the first embodiment. Therefore, substantially the same components as those of the laser radar device of the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

In the second embodiment, the rotation direction length X of the detection object is calculated based on a comparison between the shape of the light receiving waveform on the far side and the shape of the background waveform. This calculation method will be described below.
First, as shown in FIG. 11, three coordinates for determining whether or not the detected waveform exceeds a predetermined light amount in coordinates with the light amount as the vertical axis and the time as the horizontal axis (from the threshold value with the small value to Lth1). , Lth2, Lth3) are preset.

  When calculating the rotation direction length X of the detected object (in the process corresponding to step S135 or step S141), first, in the coordinates, an intersection where one threshold value intersects the detected waveform is an area calculation intersection. The area of the polygonal region surrounded by the plurality of area calculation intersection points P is calculated as the first far side area with respect to the far side received light waveform W1, and the first background side area with respect to the background waveform W2. Calculate as Next, a rectangular area surrounded by two intersection points P1a and P1b for area calculation at the minimum threshold Lth1 and perpendicular legs P0a and P0b respectively drawn from the intersection points P1a and P1b for both area calculations on the horizontal axis. The area is calculated as the long-distance side rectangular area for the light-receiving waveform W1 on the long-distance side, and is calculated as the background-side rectangular area for the background waveform W2.

  Subsequently, a total area obtained by adding the long-distance side rectangular area to the first long-distance side area (indicated by the cross-hatching region S1 in FIG. 11) and a total area obtained by adding the background-side rectangular area to the first background-side area. (Indicated in FIG. 11 by cross-hatching area S1 and hatching area S2) is calculated. The ratio of these two total areas is the ratio of the area of the region reflecting the shape of the light reception waveform W1 on the far side and the area of the region reflecting the shape of the background waveform W2, and therefore is based on this ratio. Thus, the area ratio of the detection object detected according to the light reception waveform on the short distance side to the spot cross section can be obtained. Then, the rotation direction length X of the detection object is calculated from the area ratio and the cross-sectional dimension of the spot cross section.

  Here, in the above coordinates, the area calculation intersections P1a and P1b at which the threshold value Lth1 and the detection waveform intersect are set as area calculation intersections P2a and P2b at which the threshold value Lth2 and the detection waveform intersect, and the area calculation intersection point at which the threshold Lth3 and the detection waveform intersect. Let P3a and P3b. For example, in the light reception waveform W1 on the long distance side, when there is no intersection with the threshold Lth3, the first long distance side area is surrounded by four points of area calculation intersection points P1a, P1b, P2a, and P2b. Calculated as the area of the shape area. The first background side area and the background side rectangular area may be calculated in advance when recording as a background waveform without being calculated each time as described above.

  In the second embodiment, the distance between two intersections where the waveform of the amount of light assumed to be detected by the photodiode 20 and each of the threshold values Lth1, Lth2, and Lth3 intersect is set as the threshold value for each light amount. Accordingly, the determination distance Y is measured and stored in advance. In this measurement, the time during which the received light waveform detected by the photodiode 20 exceeds the threshold by irradiating the predetermined reference object with the laser light from the laser diode 10 is the distance between the intersections in the coordinates. As (determination distance Y), it is measured at three threshold values. Then, the determination distance Y at each threshold value is measured for each light amount by changing the position of the reference object. As illustrated in FIG. 12, the measurement result is stored in advance in the memory of the control circuit 70 as a light amount-determination distance map indicating the relationship between the light amount and the determination distance Y for each threshold value.

  In the case of a normal light reception waveform, the distance between two intersections where the light reception waveform intersects with a predetermined threshold value is assumed to be substantially constant with the same threshold value and light amount. That is, it is assumed that the area calculation intersection P where the distance difference from the determination distance Y is larger than the distance difference at other thresholds is likely to be an intersection with an abnormal component included in the received light waveform. The For this reason, in the second embodiment, the first distance side area and the first background side area are calculated by using the determination distance Y as a determination criterion, excluding the intersection for area calculation with the abnormal component as described above. Processing is done.

  Further, as illustrated in FIG. 13, due to the influence of noise or the like, the distance between two intersections where the predetermined threshold intersects with the light reception waveform on the far side coincides with the determination distance Y with the same threshold and light amount. There is only one threshold value (see Y2 in FIG. 13), and the distance difference from the determination distance Y may increase with other threshold values (see Y′1 in FIG. 13). In the case illustrated in FIG. 13, it is assumed that there is no intersection between the threshold value Lth3 and the light reception waveform on the far side. In this case, excluding the area calculation intersections P1a and P1b where the distance difference is large, only two area calculation intersections P2a and P2b are assumed to be polygonal regions that reflect the shape of the light reception waveform on the far side. I can't.

  Further, as illustrated in FIG. 14, due to the two waveforms overlapping, the distance between two intersections where the predetermined threshold intersects with the light reception waveform on the long distance side, and the determination distance Y with the same threshold and light amount Is the only threshold that is considered to match (see Y3α and Y3β in FIG. 14), and the distance difference from the determination distance Y may increase with other thresholds (Y′1, Y ′ in FIG. 14). 2). In this case, except for the area calculation intersections P1a, P1b, P2a, and P2b that increase the distance difference, the two area calculation intersections P3aα and P3bα, or the two area calculation intersections P3aβ and P3bβ alone, A polygonal region in which the shape of the received light waveform is reflected cannot be assumed.

  Therefore, in the second embodiment, the distance between the intersections at other threshold values from the light amount-determination distance map (for example, see Y1 in FIG. 13) based on the distance between the intersections that is considered to coincide with the determination distance Y. ). Then, a base with one of the two line segments, the line segment having the full length of the distance between the intersections estimated in this way and the line segment having the full distance of the distance between the intersections serving as a reference, as the bottom base. Based on the region of the shape, a process for calculating the first far-side area is performed.

Hereinafter, a specific flow of the detection process according to the second embodiment will be described with reference to the flowchart of FIG.
As in the first embodiment, since the light reception signal at the pre-extraction rotation angle includes a light reception waveform different from the background waveform, if “Yes” is determined in step S115 in FIG. In step S133, it is determined whether or not there is a rotation angle in which two light reception waveforms are included in the light reception signal in the range of the waveform detection rotation angle other than the ends in both rotation directions.

  At this waveform detection rotation angle, when there is no rotation angle in which the light reception signal includes two light reception waveforms except at both ends in the rotation direction (No in S133), the reflected light from one detection object is received. In step S201, the inter-intersection distance calculation process is performed. In this process, for each of the threshold values Lth1, Lth2, and Lth3, the time during which the received light waveform exceeds the threshold value, that is, the distance between the intersections between the area calculation intersections in the coordinates is calculated.

  Next, in step S203, it is determined whether or not the distance between the intersections and the determination distance Y with the light amount substantially coincide. Here, since the received light waveform on the long distance side does not include noise or the like, the determination distance obtained from the distance between the intersections, the light amount and the threshold value based on the light amount-determination distance map (see FIG. 12). If Y substantially matches, it is determined Yes in step S203.

  In step S205, an area calculation process is performed. In this processing, in the above coordinates, the first far-side area and the far-side rectangular area, which are the areas of the polygonal regions surrounded by the respective area calculation intersection points P in the light-receiving waveform on the far side, are as described above. Thus, the calculation is performed (see FIG. 11). In addition, in the above coordinates, the first background side area and the background side rectangular area which are areas of a polygonal region surrounded by each area calculation intersection point P in the background waveform are calculated as described above (FIG. 11).

  Next, in step S207, a rotation direction length measurement process is performed. In this process, based on the ratio of the total area of the first long distance side area and the long distance side rectangular area to the total area of the first background side area and the background rectangular area, according to the light reception waveform on the short distance side. The area ratio of the detected object to be detected to the spot cross section is calculated. Subsequently, the cross-sectional dimension of the spot cross section is calculated based on the distance to the detection object based on the detection time Tn of the light reception waveform on the short distance side, and the rotation direction length of the detection object is calculated based on the cross-sectional dimension and the area ratio. X is calculated. And the process after step S137 is made like the said 1st Embodiment.

  On the other hand, if at least one of the distances between the intersections at the three thresholds is larger than the distance difference at the other thresholds, the process proceeds to step S203. Is determined as No. Then, in step S209, it is determined whether or not there are two threshold values that the distance between the intersections and the determination distance Y coincide with each other in the light amount.

  Here, if there are two threshold values that the distance between the intersections and the determination distance Y are considered to match (Yes in S209), an area calculation process is performed in step S211. In this processing, the first long distance which is the area of the polygonal region surrounded by each area calculation intersection P in the light reception waveform on the far distance side, except for the area calculation intersection where the distance difference becomes large in the coordinates. The side area and the far side rectangular area are calculated as described above. By adopting a background waveform that does not include noise or the like, the first background side area and the background side rectangular area are calculated in the same manner as in step S205. When the first far-side area and the like are calculated in this way, the rotation direction length X of the detected object is calculated in step S207 as described above.

  If there are not two threshold values that are considered to match the distance between the intersections and the determination distance Y (No in S209), in step S213, the distance between the intersections and the determination distance Y match in the amount of light. A determination is made as to whether there is only one threshold to be considered. Here, if there is one threshold value that the distance between the intersections and the determination distance Y match, it is determined Yes in step S213, and the distance between intersections is estimated in step S215. In this process, as described above, the distance between the intersections at other threshold values is estimated from the light amount-determination distance map based on the distance between the intersections that is considered to match the determination distance Y (see FIG. 13 and FIG. 13). (See FIG. 14).

  In step S217, area calculation processing is performed. In this process, in the above coordinates, a line segment having the total distance between the intersections estimated as described above (for example, Y1 in FIG. 13) and a line segment having the total distance between the reference intersection points (for example, in FIG. 13). Y2), the first far-side area is calculated based on a trapezoidal region where one of the two line segments is the upper base and the other is the lower base. By adopting a background waveform that does not include noise or the like, the first background side area and the background side rectangular area are calculated in the same manner as in step S205. When the first far-side area and the like are calculated in this way, the rotation direction length X of the detected object is calculated in step S207 as described above.

  On the other hand, if there is no threshold value at which the distance between the intersection points and the determination distance Y are considered to coincide with each other in the amount of light, it is determined No in step S213 and the rotational direction length X is not measured. The process after step S117 of FIG. 4 is performed. Here, the case where it is determined No in step S213 is, for example, that the distance Y2 between the intersections of the threshold value Lth2 and the received light waveform is the threshold value Lth3 in the light amount-determination distance map, as illustrated in FIG. In the case where it does not exist, there is a case where it is larger than the maximum determination distance Y that can appear corresponding to the threshold value Lth2. Further, as exemplified in FIG. 16, there is a case where correspondence between the distances Y1, Y2, Y3 between the intersections at each threshold and the corresponding determination distance Y is not achieved.

  In step S133 of FIG. 10 described above, when there is a rotation angle in which two light reception waveforms are included in the light reception signal other than both rotation direction ends in the waveform detection rotation angle range (Yes in S133), Similarly to the first embodiment, the second rotation direction length measurement process is performed in step S141. In this process, the ratio of the total area of the first far-side area and the far-side rectangular area to the total area of the first background-side area and the background-side rectangular area is the same as the processes after step S201 described above. Based on the above, the area ratio of the spot cross section may be calculated.

  As described above, in the laser radar device 1 according to the second embodiment, the total area obtained by adding the far-side rectangular area to the first far-side area and the background-side rectangular area are added to the first background-side area. Based on the ratio of the total area, the size of the detected object detected according to the waveform on the short distance side is measured.

  The polygonal region surrounded by each area calculation intersection P as described above is a region reflecting the shape of the corresponding waveform. For this reason, the area of each region is calculated as the first long-distance side area and the first background-side area, and by using both areas, the ratio between the light-receiving waveform and the background waveform on the long-distance side can be accurately calculated and detected. The measurement accuracy of the object size can be improved. In particular, since the ratio of the total area obtained by further adding the area of the rectangular area surrounded by the two area calculation intersections P1a, P1b and the perpendicular legs P0a, P0b at the minimum threshold Lth1, the polygonal shape is used. The area obtained by adding the rectangular area to this area is an area reflecting the shape of the corresponding waveform more than the polygonal area alone. For this reason, by using the ratio of each total area, the ratio between the light receiving waveform and the background waveform on the long distance side can be calculated with higher accuracy, and the measurement accuracy of the size of the detected object can be further improved.

  Further, in the laser radar device 1 according to the second embodiment, the distance difference between the two intersections where the predetermined threshold intersects the light reception waveform on the far side and the determination distance with the same threshold and light amount is as follows. The first far-side area and the first background-side area are calculated except for the area calculation intersection that is larger than the distance difference at other threshold values.

  As a result, the first far-side area and the first background-side area are calculated excluding the intersection between the abnormal component included in the received light waveform and the threshold value, so that the ratio between the received light waveform and the background waveform on the far distance side is Furthermore, it can be calculated with high accuracy, and the measurement accuracy of the size of the detected object can be reliably improved.

  Furthermore, in the laser radar device 1 according to the second embodiment, it is considered that the distance between two intersections where the predetermined threshold intersects the light reception waveform on the far side coincides with the determination distance with the same threshold and light amount. When there is only one threshold, the first far-side area is the same amount of light as the amount of light at the one threshold and the line connecting the intersections at the one threshold, and corresponds to the other threshold It is calculated on the basis of the area of a trapezoidal region in which one of the two line segments is the upper base and the other is the lower base.

  Thus, by estimating the distance between the intersections at other threshold values, the first far-side area can be calculated even when the light-receiving waveform on the far-side is disturbed due to noise or the like.

  As a first modification of the second embodiment, four or more threshold values may be employed. As a result, as the number of area calculation intersections P increases, that is, as the number of thresholds increases, the corresponding waveform shape is reflected as the region. The ratio can be calculated with higher accuracy. Depending on the usage environment, two threshold values may be adopted.

  As a second modification of the second embodiment, when the threshold value Lth1 is sufficiently smaller than other threshold values, the first long distance is not considered without considering the long distance side rectangular area and the background side rectangular area. By using the ratio of only the side area and the first background side area, the ratio between the received light waveform and the background waveform on the far side may be calculated. Thereby, the calculation load of the control circuit 70 in the detection process can be reduced.

[Third Embodiment]
Hereinafter, a third embodiment in which the laser radar device of the present invention is embodied will be described with reference to the drawings. FIG. 17 is a part of a flowchart illustrating the flow of detection processing in the control circuit 70 according to the third embodiment. FIG. 18 is an explanatory diagram for explaining the second far-side area and the second background-side area. FIG. 19 is an explanatory diagram illustrating a first line segment and a second line segment in a state where a waveform including noise and a threshold intersect.

  In the laser radar apparatus 1 according to the third embodiment, the flowchart shown in FIG. 17 is adopted instead of the flowchart shown in FIG. 6 in order to change the calculation method of the rotation direction length X of the detected object. However, it is different from the laser radar device according to the first embodiment. Therefore, substantially the same components as those of the laser radar device of the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

In the third embodiment, the rotation direction length X of the detection object is defined by the area of the triangular area reflecting the shape of the light receiving waveform on the far side and the area of the triangular area reflecting the shape of the background waveform. Calculate based on the comparison. This calculation method will be described below.
When calculating the rotation direction length X of the detection object (during the processing corresponding to step S135 or step S141), as shown in FIG. 18, the light quantity described in the second embodiment is used as the vertical axis and time Of the four thresholds Lth1 and Lth2 and the light receiving waveform at the coordinates where the two axes are the horizontal axis, two on the long distance side and two lines on the long distance side (P1a, P2a). Two straight lines connecting the lines (P1b, P2b) are obtained. Then, the area of the triangular region surrounded by these two straight lines and the horizontal axis is calculated as the second far-side area (indicated by the cross-hatching region S3 in FIG. 18) with respect to the far-side received light waveform W1. At the same time, the background waveform W2 is calculated as the second background side area (indicated by the cross-hatched region S3 and the hatched region S4 in FIG. 18). The ratio of these two areas is the ratio of the area of the region reflecting the shape of the light reception waveform W1 on the far side and the area of the region reflecting the shape of the background waveform W2, and therefore, based on this ratio. The ratio of the area occupied by the detection object detected in accordance with the light reception waveform on the short distance side in the spot cross section can be obtained. Then, the rotation direction length X of the detection object is calculated from the area ratio and the cross-sectional dimension of the spot cross section. Note that the second background side area may be calculated in advance when recording as a background waveform without being calculated each time as described above.

  In the third embodiment, as in the second embodiment, the distance between the intersections of the assumed light reception waveform and the threshold values Lth1 and Lth2 is determined in advance as the determination distance Y according to the threshold value for each light amount. Each is measured and stored in the memory or the like of the control circuit 70 as the light amount-determination distance map.

  In addition, as described in the second embodiment, due to the influence of noise or the like, the distance between two intersections where the predetermined threshold intersects the light reception waveform on the long distance side, and the determination distance Y with the same threshold and light amount Is considered to match only one threshold value (see Y2 in FIG. 19), and other threshold values may have a large distance difference from the determination distance Y (see Y′1 in FIG. 19).

  In this case, in the third embodiment, the line segment connecting the intersections that are considered to coincide with the determination distance Y is defined as the first line segment, and the distance between the intersections is used as a reference from the light amount-determination distance map. Estimate the distance between intersections at other thresholds. Then, a second line segment (see Y1 in FIG. 19) in which the distance for determination estimated in this way is the full length and the first bisector line coincides with the first line segment (see Y1 in FIG. 19). (See Y2 in FIG. 19) and a process of calculating the second far side area based on an area composed of an isosceles triangle passing through both end points and having the horizontal axis as the base.

Hereinafter, a specific flow of the detection process according to the third embodiment will be described with reference to the flowchart of FIG.
As in the first embodiment, since the light reception signal at the pre-extraction rotation angle includes a light reception waveform different from the background waveform, if it is determined Yes in step S115 in FIG. In step S133, it is determined whether or not there is a rotation angle in which two light reception waveforms are included in the light reception signal in the range of the waveform detection rotation angle other than the ends in both rotation directions.

  At this waveform detection rotation angle, when there is no rotation angle in which the light reception signal includes two light reception waveforms except at both ends in the rotation direction (No in S133), the reflected light from one detection object is received. In step S301, the inter-intersection distance calculation process is performed. In this process, for each of the threshold values Lth1 and Lth2, the time during which the received light waveform exceeds the threshold value, that is, the distance between the intersection points between the area calculation intersection points in the above-described coordinates is calculated.

  Next, in step S303, it is determined whether or not the distance between the intersections and the determination distance Y with the light amount substantially coincide with each other. The distance between the intersection points, the light amount and the threshold value are converted into the light amount-determination distance map. If the determination distance Y obtained based on the values is substantially equal, it is determined Yes in step S303.

  In step S305, an area calculation process is performed. In this process, a straight line connecting two area calculation intersections (P1a, P2a) on the short distance side and a straight line connecting two area calculation intersections (P1b, P2b) on the long distance side are obtained in the above coordinates. Then, the area of the triangular region surrounded by both the straight lines and the horizontal axis is calculated as the second far side area with respect to the light receiving waveform W1 on the far side, and is calculated as the second background side area with respect to the background waveform W2. (See FIG. 18).

  Next, in step S307, a rotation direction length measurement process is performed. In this process, based on the ratio between the second far-side area and the second background-side area, the area ratio of the detected object, which is detected according to the near-field received light waveform, to the spot cross section is calculated. Subsequently, the cross-sectional dimension of the spot cross section is calculated based on the distance to the detection object based on the detection time Tn of the light reception waveform on the short distance side, and the rotation direction length of the detection object is calculated based on the cross-sectional dimension and the area ratio. X is calculated. And the process after step S137 is made like the said 1st Embodiment.

  On the other hand, if at least one of the distances between the intersections at the two thresholds is larger than the distance difference at the other thresholds, the process proceeds to step S303. Is determined as No. Then, in step S309, it is determined whether or not there is only one threshold that is considered to match the distance between the intersections and the determination distance Y with respect to the amount of light.

  Here, when there is one threshold value that the distance between the intersections and the determination distance Y match (Yes in S309), the distance between intersections is estimated in step S311. In this process, as described above, the distance between the intersections at other threshold values is estimated from the light amount-determination distance map on the basis of the distance between the intersections considered to be coincident with the determination distance Y (see FIG. 19). ).

  In step S313, an area calculation process is performed. In this process, the line segment connecting the intersections that are considered to coincide with the determination distance Y as described above at the coordinates is defined as the first line segment (for example, Y2 in FIG. 19) and the determination estimated as described above. A second distance (for example, Y1 in FIG. 19) in which the first distance and the perpendicular bisector coincide with each other with the working distance as a full length is obtained. Then, the second long-distance side area is calculated based on an area composed of isosceles triangles passing through the end points of both line segments and having the horizontal axis as the base. By adopting a background waveform that does not include noise or the like, the second background side area is calculated in the same manner as in step S305. When the second far-side area is calculated in this way, the rotation direction length X of the detected object is calculated in step S307 as described above.

  On the other hand, as described in the second embodiment, when there is no threshold value at which the distance between the intersections and the determination distance Y are equal to each other in the light amount, it is determined No in step S309, The process after step S117 in FIG. 4 is performed without measuring the length X in the rotation direction.

  In step S133 of FIG. 17 described above, when there is a rotation angle in which two light reception waveforms are included in the light reception signal other than both rotation direction ends in the waveform detection rotation angle range (Yes in S133), Similarly to the first embodiment, the second rotation direction length measurement process is performed in step S141. In this process, the area ratio of the spot cross section may be calculated based on the ratio of the second far-side area and the second background-side area, as in the processes after step S301 described above.

  As described above, in the laser radar device 1 according to the third embodiment, detection is performed according to the waveform on the near side, based on the ratio between the second far side area and the second background side area. The size of the detected object is measured.

  The triangular area as described above is an area reflecting the shape of the corresponding waveform. In particular, only by setting at least two threshold values, a region reflecting the corresponding waveform shape is partitioned. For this reason, the area of each region is calculated as the second long-distance side area and the second background-side area, and the ratio of both areas can be used to accurately calculate the ratio of the light-receiving waveform and the background waveform on the long-distance side. The measurement accuracy of the size of the detected object can be improved.

  Further, in the laser radar device 1 according to the third embodiment, the distance between two intersections where the predetermined threshold intersects with the light reception waveform on the long distance side and the determination distance with the same threshold and the same light amount are considered to match. When there is only one threshold, the second far-side area is the area of an isosceles triangle that passes through the end points of both the first line segment and the second line segment and has the horizontal axis as the base. Calculated based on area.

  As described above, by estimating the distance between the intersections at other threshold values, the second far-side area can be calculated even when the light-receiving waveform on the far-side is disturbed due to noise or the like.

  As a first modification of the third embodiment, three or more threshold values may be employed. In this case, the second far-side area and the second background-side area may be calculated based on the four area calculation intersections P that are considered to be matched by the determination distance Y. Similarly to the second embodiment, the second far-side area and the second background-side area are calculated except for the area calculation intersection at an abnormal component that increases the distance difference from the determination distance Y. Can do.

  As a second modification of the third embodiment, as described above, the rotation direction length X of the detection object is calculated based on the second far-side area and the second background-side area, and the second embodiment. As described above, the rotation direction length X of the detection object may be calculated based on the first long distance side area, the first background side area, and the like. In this case, the rotation direction length X with higher accuracy can be calculated by comparing the calculated rotation direction lengths X. Further, in order to effectively utilize each measurement accuracy, when there are three or more threshold values that are considered to match the determination threshold value with the same threshold value and light amount, the first far side area and the first background side When the rotation direction length X of the detection object is calculated based on the area or the like, and there are two threshold values that are considered to be the same threshold value and the determination distance with the same amount of light, the second far-side area and the second The rotation direction length X of the detection object may be calculated based on the background side area.

The present invention is not limited to the above embodiments, and may be embodied as follows. Even in this case, the same operations and effects as those of the above embodiments can be obtained.
(1) In the rotation direction length measurement process, the area ratio of the detection object detected in accordance with the light reception waveform on the short distance side to the spot cross section is calculated from the amplitude value Hf of the light reception waveform on the long distance side and the background waveform. The calculation is not limited to the ratio based on the ratio to the amplitude value Ho. For example, the ratio is the ratio between the time when the far-side waveform is equal to or greater than a predetermined threshold and the time when the background waveform is equal to or greater than the predetermined threshold. You may calculate based on. As the area occupied by the detected object in the spot cross section becomes smaller, the time during which the far-side waveform is greater than or equal to the predetermined threshold changes so as to approach the time during which the background waveform is greater than or equal to the predetermined threshold. For this reason, the area ratio of the detected object to the spot cross section is calculated based on the ratio of the time when the far-side waveform is above the predetermined threshold and the time when the background waveform is above the predetermined threshold. And the size of the detected object can be easily measured.

(2) In steps S107 and S117, the determination reference is not limited to one round from the reference rotation angle. For example, a half turn may be used as the determination reference, and a plurality of rounds may be used as the determination reference. Also good.

(3) In the second rotation direction length measurement process in step S141, when the above-mentioned area ratio in the spot cross section where two received light waveforms are detected at other than the ends in both rotation directions is close to 1, that is, this spot When the amplitude value Hf of the light reception waveform on the far distance side in the cross section is sufficiently small with respect to the background waveform, it is assumed that there is one light reception waveform in the spot cross section and the first rotational direction length measurement process is performed. Similarly, the rotation direction length X may be calculated.

  In the second rotation direction length measurement process, if the use environment requires high security, the rotation direction length X is the same as the first rotation direction length measurement process regardless of the area ratio. And the detection object detection frequency may be increased by calculating the rotation direction length X of the detection object.

  In addition, in the case where the spot cross-sections in which two light receiving waveforms are detected other than at both ends in the rotational direction are continuous, a part of the spot cross-section Ln-3 is the two detected objects as illustrated in FIG. 9A. FIG. 9B illustrates a state in which a part of the spot cross section Ln-4 is reflected by one of the partial irradiation units, and a part of the spot cross section Ln-4 is reflected by the other partial irradiation unit of the two detection objects. In addition, it is impossible to determine which state is a state in which a part of the spot cross-sections Ln-3 and Ln-4 is reflected by a detection object existing between two detection objects.

  Therefore, in such a case, in the second rotation direction length measurement process, the process may be changed according to required security. Specifically, for example, in a use environment where high security is required, the detection object is calculated by calculating the rotation direction length X in the same manner as the first rotation direction length measurement process regardless of the area ratio. The detection object detection frequency may be increased by calculating so that the rotation direction length X of the detection object increases. Further, in a usage environment where high security is not required, it is detected by calculating the rotational direction length X of each detection object on the assumption that a plurality of detection objects are detected according to the above-mentioned area ratio or the like. You may make it prevent reliably the detection of the detection object of an unnecessary magnitude | size.

(4) In the rotation direction length measurement processing in steps S135 and S141, the spot cross sections at the current rotation angle are the same distance according to the set value of the unit angle change (laser scanning interval) in the laser beam emission direction. If it overlaps with the spot cross section at the pre-extraction rotation angle at, the overlap may be subtracted from the calculated rotation direction length X. Thereby, the rotational direction length X of the detection object can be calculated and measured more accurately.

DESCRIPTION OF SYMBOLS 1 ... Laser radar apparatus 10 ... Laser diode (laser beam generation means)
20 ... Photodiode (light detection means)
40... Turning deflection mechanism (turning deflection means)
50. Motor (driving means)
70. Control circuit (distance measuring means, setting means, measuring means, cross-sectional dimension calculating means)
L: Spot section Hf, Ho: Amplitude value Tf, Tn, To: Detection time X: Length in rotation direction P: Intersection point for area calculation Y: Distance for determination

Claims (14)

Laser light generating means for generating laser light;
A light detection means for detecting, as a waveform, reflected light reflected by a detection object when the laser light is generated from the laser light generation means;
A deflection unit configured to be rotatable about a predetermined central axis is provided. The laser beam is deflected toward the space by the deflection unit, and the reflected light is deflected toward the light detection unit. Dynamic deflection means;
Drive means for driving the rotation deflection means;
The distance to the detection object is determined based on the detection time from the generation of the laser light by the laser light generation means until the reflected light reflected by the detection object is detected by the light detection means. A distance measuring means for measuring;
A laser radar device comprising:
When a detection state that the waveform detected by the light detection means at a predetermined rotation angle is considered to coincide with the waveform detected at the same previous rotation angle is continuously detected, this waveform is converted to the rotation angle. Setting means for setting as a background waveform of
When two waveforms corresponding to the detection time of the background waveform at the rotation angle corresponding to the detection time of the waveform on the long distance side are detected by the light detection means, the waveform on the long distance side and the background waveform are detected. Measurement means for measuring the size of the detected object detected according to the waveform on the near distance side based on the ratio of
A laser radar device comprising:   The measuring means measures the size of the detected object detected according to the near-field waveform based on a ratio between the far-field waveform amplitude value and the background waveform amplitude value. The laser radar device according to claim 1.   The measuring means may calculate the near-field waveform based on a ratio between a time when the far-side waveform is equal to or greater than a predetermined threshold and a time when the background waveform is equal to or greater than the predetermined threshold. The laser radar device according to claim 1, wherein the size of the detected object detected in response is measured.   The invalidity means which invalidates the detection of this detection object when the size of the detection object measured by the measurement means is out of the detection object is provided. The laser radar device described.   The laser radar device according to claim 4, wherein the size of the detection object to be detected is set according to a distance measured by the distance measurement unit. The measuring means includes
A cross-sectional dimension calculating means for calculating a cross-sectional dimension of the laser beam at a measurement distance to the detection object by the distance measuring means;
The two waveforms are detected by the light detection means at a first rotation angle by a part of the detection object, and all of the detection object is rotated by a predetermined angle from the first rotation angle by the remaining part of the detection object. When one waveform is detected by the light detection means at a rotation angle of
Measuring the length along the rotation direction of the detection object based on the number of rotation angles at which the one waveform is detected, the ratio of the two waveforms, and the cross-sectional dimension; The laser radar device according to any one of claims 1 to 5.   The laser radar device according to claim 6, wherein the cross-sectional dimension calculating unit calculates the cross-sectional dimension at the measurement distance according to a spread of the laser light. A plurality of thresholds for determining whether or not the waveform detected by the light detection means exceeds a predetermined light amount are set,
In the coordinates where the light amount is on the vertical axis and the time is on the horizontal axis, the intersection where one threshold value intersects with the waveform detected by the light detection means is the intersection for area calculation,
The measuring means includes
A first far-side area that is an area of a polygonal region surrounded by a plurality of intersections for area calculation where two or more of the plurality of thresholds and the far-side waveform intersect;
Based on the ratio of the first background side area, which is the area of a polygonal region surrounded by the plurality of area calculation intersections where the two or more threshold values intersect the background waveform,
The laser radar device according to claim 1, wherein the size of the detected object detected according to the waveform on the short distance side is measured. The measuring means includes
The area of a quadrangular region surrounded by the two intersection points for area calculation at the minimum threshold value that constitutes the first far-side area and the legs of the perpendicular line respectively drawn on the horizontal axis from these intersection points for area calculation Total area added to the first far side area,
The area of a quadrangular region surrounded by the two intersection points for area calculation at the minimum threshold value constituting the first background side area and the perpendicular legs drawn down from the intersection points for both area calculations to the horizontal axis respectively. Based on the ratio of the total area added to the first background side area,
9. The laser radar device according to claim 8, wherein a size of the detected object detected in accordance with the waveform on the short distance side is measured. The distance between two intersections where the light intensity waveform assumed to be detected by the light detection means and the threshold value is measured and stored in advance as a determination distance according to the threshold value for each light quantity,
The measuring means includes
The distance difference between the two intersections where the predetermined threshold value intersects the waveform on the long distance side and the determination distance with the same threshold value and light amount is larger than the distance difference with other threshold values Excluding the intersection for area calculation,
The laser radar device according to claim 8 or 9, wherein the first far-side area and the first background-side area are calculated. The measuring means includes
When the distance between two intersections where the predetermined threshold intersects the waveform on the far distance side and the determination threshold with the same threshold and the same amount of light are considered to match, there is only one threshold,
The first long distance side area,
Two lines: a line segment connecting the intersections at the one threshold value, and a line segment having the same light amount as the light amount at the one threshold value and having the determination distance corresponding to the other threshold as a full length 11. The laser radar device according to claim 10, wherein the calculation is performed based on an area of a trapezoidal region in which one of the minutes has an upper base and the other has a lower base. A plurality of thresholds for determining whether or not the waveform detected by the light detection means exceeds a predetermined light amount are set,
In the coordinates where the light amount is on the vertical axis and the time is on the horizontal axis, the intersection where one threshold value intersects with the waveform detected by the light detection means is the intersection for area calculation,
The measuring means includes
Of the four intersections for area calculation where two of the plurality of thresholds intersect the waveform on the long distance side, a straight line connecting two on the short distance side and a straight line connecting two on the long distance side A second far side area that is an area of a triangular region surrounded by two straight lines and the horizontal axis;
Of the four intersections for area calculation where the two thresholds intersect the background waveform, two straight lines connecting two on the short distance side and two straight lines connecting two on the long distance side, and the horizontal axis Based on the ratio of the area of the triangular region to be surrounded and the second background side area,
The laser radar device according to claim 1, wherein the size of the detected object detected according to the waveform on the short distance side is measured. The distance between two intersections where the light intensity waveform assumed to be detected by the light detection means and the threshold value is measured and stored in advance as a determination distance according to the threshold value for each light quantity,
The measuring means includes
The area in which the difference between the predetermined threshold and the distance for determination with the same threshold and light amount as the distance between two intersections where the predetermined distance intersects the waveform on the far side is larger than the distance difference at other thresholds Excluding the intersection for calculation,
13. The laser radar device according to claim 12, wherein the second long distance side area and the second background side area are calculated. The measuring means includes
When the distance between two intersections where the predetermined threshold intersects the waveform on the far distance side and the determination threshold with the same threshold and the same amount of light are considered to match, there is only one threshold,
The second far side area is
The first line segment connecting the intersections at the one threshold value and the determination distance corresponding to the other threshold value with the same light amount as the light amount at the one threshold value is defined as the total length. The calculation is based on the area of an isosceles triangle that passes through the end points of both the line segment and the second line segment in which the perpendicular bisector matches and has the horizontal axis as the base. The laser radar device according to claim 13.

Images