JP2006349694A - Object detection device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable it to detect an object surely and simply, even when an inclination in the upper and lower sides at the detection region arises. <P>SOLUTION: A laser radar of a vehicle 11 scans a laser light like the laser light may irradiate to a vertical region from 81 to 85. The laser light is reflected by a vehicle 12 and is received by the laser radar of the vehicle 11. The laser radar detects the vertical region where the light received amount becomes the maximum (for example, the vertical region 84) among the light received amount of each region of the vertical region from 81 to 85. The laser radar corrects an axis deviation of a position of the detected vertical region 84 so as to position a center region 83 in vertical region from 81 to 85. This invention can be applied to the vehicle laser radar. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an object detection apparatus and method, for example, an object detection apparatus and method suitable for use in vehicle detection of an automobile.

  The vehicle laser radar detects the preceding vehicle by receiving the reflected wave of the laser beam transmitted forward in the traveling direction of the vehicle, and automatically issues an alarm for avoiding a collision with the preceding vehicle. There is something to emit.

  In such a vehicular laser radar, in order to prevent erroneous detection of an obstacle due to a mounting error of the vehicular laser radar with respect to the vehicle body or a tilt of a detection area due to the loading state of the vehicle, a laser beam that spreads in the vertical direction is used. The first direction and the second direction above the first direction are emitted at different timings, and the received waves of the reflected waves have the same reception intensity in the direction perpendicular to the optical axis of the laser beam. It is known to adjust the angle (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2000-56020 (FIG. 5)

  However, in the invention of Patent Document 1, a plurality of laser beams having different angles in the vertical direction are emitted, so that a plurality of laser diodes are required, and the structure of the laser radar is complicated. In addition, since a laser beam having a wide width in the vertical direction is used, there is a high possibility that reflected light from a road, a pedestrian bridge arranged on the road, a sign, or the like is erroneously detected as a vehicle. . Further, there is a problem that correction cannot be performed if there is no detection target.

  The present invention has been made in view of such a situation, and an object thereof is to make it possible to reliably detect an object to be originally detected with a simple configuration.

  The object detection apparatus of the present invention includes an emitting unit that emits an electromagnetic wave while scanning in a horizontal and vertical direction in a scan range, a receiving unit that receives a reflected wave of the electromagnetic wave, and a reflected wave received by the receiving unit. An acquisition means for acquiring a level; an arithmetic means for calculating a first deviation correction amount based on a vertical position of an area where the level of the reflected wave is maximum; and a vertical center position of the scan range; Correction means for correcting the position of the center in the vertical direction of the scan range based on the first deviation correction amount calculated by the means, and measuring the distance from the object by the reflected wave. Scan in the first direction, which is a predetermined direction in the horizontal direction, in the center area centered on the vertical center position of the range, and in the area above the center area, the first direction The first scan processing that emits while scanning in the second direction that is opposite to the first direction, scan in the first direction in the central region, and emits while scanning in the second direction in the region below the central region The second scan process is performed.

  In the object detection device of the present invention, in the center region centered on the vertical center position of the scan range, the scan is performed in the first direction which is a predetermined direction in the horizontal direction, and the region above the center region , A first scan process for emitting an electromagnetic wave while scanning in a second direction opposite to the first direction, a scan in the first direction in the central region, and a second in the region below the central region. The second scanning process for emitting an electromagnetic wave while scanning in the direction is performed, the reflected wave of the electromagnetic wave is received, and the level of the received reflected wave is acquired. The first deviation correction amount is calculated based on the vertical position of the region where the level of the reflected wave is maximum and the vertical center position of the scan range, and the calculated first deviation correction amount is calculated. Based on this, the vertical center position of the scan range is corrected.

  Therefore, it is possible to correct the position of the center in the vertical direction of the scan range in the region where the amount of reflected waves received is maximum, and to reliably detect the object.

  The acquisition unit, the calculation unit, and the correction unit are realized, for example, when the control circuit executes a predetermined program.

  The first holding means for holding the first deviation correction amount for each scan of the scan range is further provided, and the computing means next time according to the previous first deviation correction amount held by the first holding means. The first deviation correction amount can be calculated.

  When the difference between the previous first deviation correction amount held by the first holding means and the next first deviation correction amount is equal to or greater than a predetermined value, the calculation means calculates the next first deviation correction amount. The sum of the previous first deviation correction amount and the predetermined value can be determined.

  Thereby, it is possible to suppress the influence on the optical axis deviation correction amount due to the instantaneous optical axis deviation.

  The first holding unit is constituted by a memory, for example. In addition, the first holding unit can be configured by a storage unit such as a hard disk that can hold data even when the power is turned off.

  Storage means for storing the first deviation correction amount and the histogram of the number of corrections performed by the correction means is further provided, and corresponds to the first deviation correction amount of the histogram when the first deviation correction amount satisfies a predetermined condition. It is possible to add 1 to the number of corrections to be made.

  The conditions can be such that the distance between the vehicle and the object is within a predetermined range, the absolute value of the first deviation correction amount is within a predetermined value, and the speed of the vehicle is greater than or equal to a predetermined value. .

  A first determination unit that determines whether or not an object has been detected; and if the first determination unit determines that no object is detected, whether or not the statistical number of the histogram is greater than a predetermined reference value When the second determination means and the second determination means determine that the statistical number of histograms is greater than the reference value, the first deviation correction amount with the largest number of histogram corrections is set as the second deviation correction amount. And a correction unit that further corrects the vertical center position of the scan range based on the second shift correction amount.

  Thereby, even when the object is not detected, the optical axis deviation can be corrected.

  The first determination unit, the second determination unit, and the setting unit are realized by, for example, a control circuit that executes a program. The storage means is constituted by a memory, for example. In addition, the storage means can be configured by a storage unit such as a hard disk that can hold data even when the power is turned off.

  And a second holding unit that holds the second deviation correction amount, and a third determination unit that determines whether or not the second deviation correction amount is held by the second holding unit. When the third determination unit determines that the second shift correction amount is held, the center position in the vertical direction of the scan range is corrected based on the second shift correction amount. be able to.

  When the third determination unit determines that the second deviation correction amount is not held, the correction unit corrects the position of the center in the vertical direction of the scan range based on the preset deviation correction amount. Can be.

  Thereby, even if the number of statistics of the histogram is small, if there is a previous optical axis deviation correction amount determined based on the histogram, the optical axis deviation can be corrected based on that. Further, even when there is no previous optical axis deviation correction amount determined based on the histogram, the optical axis deviation can be corrected based on a predetermined value determined in advance.

  The third determination unit is realized by, for example, a control circuit that executes a program. The second holding means is constituted by a memory, for example. In addition, the second holding means can be configured by a storage unit such as a hard disk that can hold data even when the power is turned off.

  Based on the level of the reflected wave acquired by the acquisition unit, the image processing apparatus further includes a determination unit that determines whether or not the preceding vehicle has been detected, and the calculation unit reflects the reflection when the determination unit determines that the preceding vehicle has been detected. The first deviation correction amount can be calculated based on the vertical position of the region where the wave level is maximum and the vertical center position of the scan range.

  The determination unit is realized by, for example, a control circuit that executes a program.

  The object detection method of the present invention includes an emission step of emitting an electromagnetic wave while scanning in the horizontal and vertical directions in a scan range, a reception step of receiving a reflected wave of the electromagnetic wave, and a reflection received by processing of the reception step. An acquisition step for acquiring a wave level, a calculation step for calculating a first shift correction amount based on a vertical position of a region where the level of the reflected wave is maximum, and a vertical center position of the scan range; A correction step of correcting the position of the center of the scan range in the vertical direction based on the first deviation correction amount calculated by the processing of the calculation step, and measuring the distance from the object by the reflected wave. The processing of the step is the first direction that is a predetermined direction in the horizontal direction in the central region centered on the vertical center position of the scan range. A first scan process of scanning and emitting in a second direction that is opposite to the first direction in the region above the central region, and scanning in the first direction in the central region; And a second scan process of emitting while scanning in the second direction in the lower region.

  Therefore, as in the case of the object detection apparatus of the present invention, the position of the center in the vertical direction of the scan range can be corrected in the region where the received light amount of the reflected wave is maximum, and the object can be detected reliably.

  The emission step is configured by an emission step that emits while scanning in the scan range in the horizontal direction and the vertical direction based on a signal from the control circuit, for example, and the acquisition step includes, for example, a photodiode that receives a reflected wave of an electromagnetic wave The acquisition step acquires the level of the reflected wave processed by the light receiving circuit based on the signal from the control circuit. The calculation step is a calculation step for calculating a short-term optical axis deviation correction amount by the control circuit based on, for example, the vertical position of the region where the level of the reflected wave is maximum and the vertical center position of the scan range. The correction step includes, for example, a correction step in which the control circuit corrects the position of the center in the vertical direction of the scan range based on the short-term optical axis deviation correction amount.

  As described above, according to the present invention, an object can be detected. In addition, the optical axis of the emitted electromagnetic wave can be corrected. Furthermore, even when there is no object, the optical axis of the electromagnetic wave can be corrected.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an embodiment of a vehicle laser radar system to which the present invention is applied. As shown in the figure, the vehicle 11 emits laser light to the vehicle 12, and measures the distance between the vehicle 11 and the vehicle 12 by reflected light from the vehicle 12.

  FIG. 2 is a block diagram showing a configuration of a distance measuring device (laser radar) 20 provided in the vehicle 11. An LD (Laser Diode) drive circuit 22 controls light emission of the LD 23 based on the drive signal generated by the control circuit 21. The scanner 25 scans the laser beam generated by the LD 23 within a predetermined scan range based on the control of the control circuit 21. The laser light emitted from the scanner 25 is emitted in the traveling direction of the vehicle 11 (right direction in FIG. 1) through the light projection lens 24. The vertical scanning position detection device 26 and the horizontal scanning position detection device respectively detect the scanning (scanning) positions of the laser light in the horizontal direction and the vertical direction in the scanner 25 and output them to the control circuit 21.

  The reflected light returned from the laser beam emitted from the LD 23 after being reflected by an object (for example, the vehicle 12) as a detection target is collected by a light receiving lens 28 and received by a PD (Photo Diode) 29. A signal corresponding to the level is output to the light receiving circuit 30. The light receiving circuit 30 digitizes the signal level of the input reflected light and outputs it to the control circuit 21. The control circuit 21 stores the input numerical value (light reception level) in the memory 31 corresponding to the scanning position input from the vertical scanning position detection device 26 and the horizontal scanning position detection device 27. The memory 31 also stores an optical axis deviation correction amount and a histogram (FIGS. 9 and 10 described later). The vehicle measurement sensor 32 detects the vehicle measurement of the own vehicle (vehicle 11) and outputs it to the control circuit 21.

  The control circuit 21 corrects the optical axis (vertical center position of the scan range) based on the light reception level stored in the memory 31, and based on the time from when the laser beam is emitted until it is received, Measure the distance between the preceding vehicle (detection target) and the vehicle.

  FIG. 3 shows a configuration of a portion of the scanner 25 that supports the light projecting lens 24 and the light receiving lens 28.

  A control signal from the control circuit 21 is input to the drive circuit 41. The drive circuit 41 supplies a drive current to the horizontal direction drive coil 42 and the vertical direction drive coil 44 based on the input control signal. The horizontal direction driving coil 42 and the vertical direction coil 44 move the support member 51 that integrally supports the light projecting lens 24 and the light receiving lens 28 in the horizontal direction or the vertical direction, respectively. The support member 51 is also supported by a horizontal leaf spring 43 and a vertical leaf spring 45 so as to be movable in the horizontal direction or the vertical direction, respectively. Accordingly, the support member 51 (the light projecting lens 24 and the light receiving lens 28) moves to a horizontal position where the force generated in the horizontal driving coil 42 by the driving current and the reaction force generated in the horizontal leaf spring 43 are balanced. In addition to being stationary, it moves to a position where the force generated in the vertical driving coil 44 and the reaction force generated in the vertical leaf spring 45 are balanced, and is stationary.

  In this way, the light projecting lens 24 and the light receiving lens 28 can move to predetermined positions in both the horizontal direction and the vertical direction.

  The optical paths of the light projecting lens 24 and the light receiving lens 28 driven by the scanner 25 are shown in FIG. The light projecting lens 24 is provided on the front surface of the LD 23, and the light receiving lens 28 is provided on the front surface of the PD 29.

  The laser light emitted from the LD 23 is polarized in the center direction of the light projecting lens 24. When the position of the light projecting lens 24 is at the center, the laser beam is emitted to the front along the optical path as indicated by the solid line in FIG. The emitted laser light is reflected by a detection target (for example, the vehicle 12), enters the light receiving lens 28 through an optical path as indicated by a solid line in FIG. 4, and is received by the PD 29.

  Further, when the light projection lens 24 is moved upward in the drawing by the scanner 25 (FIG. 3), the laser light is emitted upward in the drawing along an optical path as indicated by a dotted line in FIG. . Then, the emitted laser light is reflected by an upward detection target in the figure, enters the light receiving lens 28 through an optical path as indicated by a dotted line in FIG. 4, and is received by the PD 29.

  In this manner, the scanner 25 scans the laser light in the horizontal direction by moving the light projecting lens 24 and the light receiving lens 28 integrally to a predetermined position in the horizontal direction. Similarly, the scanner 25 scans the laser light in the vertical direction by moving the light projecting lens 24 and the light receiving lens 28 integrally in the vertical direction.

  5 and 6 are diagrams illustrating examples of scan ranges in the horizontal direction and the vertical direction when the vehicle 11 emits laser light to the vehicle 12. As shown in FIG. 5, the horizontal scan range is divided into seven regions, horizontal regions 61 to 67, and as shown in FIG. 6, the vertical scan range is divided into vertical regions 81 to 67. It is divided into 85 areas.

  FIG. 7 shows the scanning direction of the scanner 25 when the laser beam is scanned over the scanning range as shown in FIGS. The vertical region 83 is a central region among the five regions in the vertical direction, and in this region, scanning is performed from the horizontal region 61 toward the horizontal region 67 (main scan 1). On the other hand, the vertical area 81 and the vertical area 82 above the vertical area 83 are scanned from the horizontal area 67 toward the horizontal area 61 (sub scan 1 and sub scan 2). Similarly, in the vertical region 84 and the vertical region 85 below the vertical region 83, scanning is performed from the horizontal region 67 toward the horizontal region 61 (sub scan 3 and sub scan 4).

  FIG. 8 is a diagram illustrating an example of the execution order of the main scan 1 and the sub-scans 1 to 4 when the entire scan range is scanned. In step S <b> 1, the scanner 25 performs the main scan 1 (scan that performs the vertical area 83 from the horizontal area 61 toward the horizontal area 67). In step S <b> 2, the scanner 25 performs sub-scan 1 (scan in which the vertical area 81 is moved from the horizontal area 67 toward the horizontal area 61). In step S3, the scanner 25 performs main scan 1, and in step S4, performs sub-scan 2 (scan in which the vertical region 82 is moved from the horizontal region 67 toward the horizontal region 61).

  In step S5, the scanner 25 performs the main scan 1, and in step S6, performs the sub-scan 3 (scan in which the vertical region 84 is moved from the horizontal region 67 toward the horizontal region 61). In step S7, the scanner 25 performs main scan 1, and in step S8, performs sub-scan 4 (scan in which the vertical region 85 is moved from the horizontal region 67 toward the horizontal region 61). The time for each scan is 50 ms. The eight scans of steps S1 to S8 are a set of scans in the scan range.

  In the present invention, the deviation of the optical axis of the laser radar 20 is corrected in the short term and also in the long term. The short-term optical axis deviation is an optical axis deviation of several seconds such as vertical movement of the own vehicle during acceleration / deceleration and vertical movement of the preceding vehicle on a slope. Further, the long-term optical axis deviation is an optical axis deviation due to a vertical inclination due to a change in the load weight of the own vehicle, a light collision, or the like. Furthermore, there is an instantaneous optical axis shift due to an instantaneous vertical movement of the vehicle due to a gap on the road surface, etc., but in the present invention, this instantaneous optical axis shift is not corrected in order to prevent erroneous detection.

  Processing for correcting the optical axis in the vertical direction by the control circuit 21 will be described with reference to the flowcharts of FIGS. In step S21, the control circuit 21 initializes a histogram stored in the memory 31 (stored in the process of step S30 in FIG. 10 described later).

  FIG. 11 shows an example of a histogram stored in the memory 31. The figure shows the number of corrections (vertical axis) corresponding to the optical axis deviation correction amount (horizontal axis). In the example of FIG. 11, the number of times that the optical axis misalignment correction of −2 degrees is performed is 8 times, and the number of times that the optical axis misalignment correction of −1 degrees is performed is 40 times. The number of times that the optical axis misalignment correction was not performed is 100, which is the largest number, and the number of times that one optical axis misalignment correction is performed is 70 times. The number of times that the optical axis misalignment correction is performed twice is the smallest two times. In the process of step S21, these correction times are all zero.

  In step S22, the control circuit 21 sets a specified value set in advance at the time of factory shipment as the optical axis deviation correction amount. This specified value is also stored in the memory 31. In step S23, the control circuit 21 controls the scanner 25 and corrects the optical axis based on the set optical axis correction amount. That is, as shown in FIG. 3, the control circuit 21 supplies a control signal to the drive circuit 41 of the scanner 25 and supplies a current having a magnitude corresponding to the control signal to the vertical driving coil 44. The vertical leaf spring 45 connected to the support member 51 that supports the light projecting lens 24 and the light receiving lens 28 moves to a position where the force generated in the coil by the current and the reaction force generated in the leaf spring are balanced. As a result, the vertical position of the scan range is set to the factory default position.

  An example of setting the position of the center of the scan range in the vertical direction (hereinafter also simply referred to as the position of the scan range in the vertical direction) will be described with reference to FIGS. In this example, the movable range in the vertical direction of the scanner 25 is 8 degrees, and a range of 4 degrees out of 8 degrees is a scan range.

  FIG. 12 shows an example of the vertical position of the scan range set by the scanner 25 when the optical axis correction amount is 0 degrees (the optical axis is not corrected). In this example, the main scan 1 is set at the center of the vertical movable range. The sub scan 2 is set upward by 1 degree from the main scan 1, and the sub scan 1 is set upward by 1 degree (total of 2 degrees). Further, the sub-scan 3 is set downward by 1 degree from the main scan 1, and the sub-scan 4 is further set downward by 1 degree (total of 2 degrees). Accordingly, in this case, a range of 2 degrees remains as the margin for optical axis correction both in the upper and lower directions. The specified value set in step S22 is set to this value.

  FIG. 13 shows an example of the position in the vertical direction of the scan range set by the scanner 25 when the optical axis correction amount is 1 degree (corrected once upward). In this example, the main scan 1 is set upward by one degree from the center of the vertical movable range. As in the case of the example of FIG. 12, the subscan 2 is set upward by 1 degree from the main scan 1, and the subscan 1 is upward by 1 degree from the subscan 2 (main scan 1). (Upward by 2 degrees). Subscan 3 is set to the center of the vertical movable range (downward from main scan 1 by 1 degree), and subscan 4 is downward from subscan 3 by 1 degree (down from main scan 1 by 2 degrees). Direction). Therefore, in this case, what remains as a margin for optical axis correction is a range of 1 degree on the upper side and 3 degrees on the lower side.

  FIG. 14 shows an example of the vertical position of the scan range set by the scanner 25 when the optical axis correction amount is −2 degrees (corrected by 2 degrees downward). In this example, the main scan 1 is set downward by 2 degrees from the center of the vertical movable range. The sub-scan 2 is set once upward from the main scan 1, and the sub-scan 1 is set upward by one degree from the sub-scan 2 (up by two degrees from the main scan 1). Further, the sub-scan 3 is set downward by 1 degree from the main scan 1, and the sub-scan 4 is set downward by 1 degree from the sub-scan 3 (down by 2 degrees from the main scan 1). Therefore, in this case, what remains as a margin for optical axis correction is 4 degrees on the upper side and 0 degree on the lower side.

  In step S24, the control circuit 21 controls the scanner 25 to scan only one set of the set scan range in the direction and order as shown in FIGS. The scanned laser light is reflected by the object and received by the PD 29. The light photoelectrically converted by the PD 29 is digitized by the light receiving circuit 30. In step S <b> 25, the control circuit 21 obtains a light reception amount (light reception level) that is digitized from the light reception circuit 30.

  FIG. 15 is a diagram illustrating an example of the amount of received light acquired from the light receiving circuit 30 as a result of the process of step S25. In the table, all items without numerical values indicate that the received light amount is “0”.

  In the example of FIG. 15, the amount of light received from the horizontal region 64 in the vertical region 81 is “10”. In the vertical region 82, the amount of light received from the horizontal region 63 is “20”, the amount of light received from the horizontal region 64 is “100”, and the amount of light received from the horizontal region 65 is “25”. The amount of light received from the horizontal region 63 in the vertical region 83 is “90”, the amount of light received from the horizontal region 64 is “150”, and the amount of light received from the horizontal region 65 is “100”. The amount of light received from the horizontal region 63 in the vertical region 84 is “150”, the amount of light received from the horizontal region 64 is “200”, and the amount of light received from the horizontal region 65 is “160”. In the vertical region 85, the amount of light received from the horizontal region 63 is “80”, the amount of light received from the horizontal region 64 is “180”, and the amount of light received from the horizontal region 65 is “75”.

  In step S26, the control circuit 21 determines whether or not a preceding vehicle has been detected. For example, when the maximum amount of received light (“200” in the example of FIG. 15) is equal to or greater than a predetermined reference value set in advance, it is determined that the preceding vehicle has been detected. If it is determined that the preceding vehicle has been detected, the control circuit 21 advances the processing to step S27, and executes processing for determining a short-term optical axis deviation correction amount. Details of this processing will be described with reference to the flowchart of FIG.

  In step S51, the control circuit 21 detects a vertical region where the amount of received light is maximum. That is, in the case of the example of FIG. 15, the vertical region 84 where the value of the amount of received light is “200” is detected. In step S <b> 52, the control circuit 21 calculates the angle offset amount of the vertical region (the vertical region where the light reception amount value is maximum) from the vertical movable center of the scanner 25 as the optical axis deviation amount. That is, in the example of FIG. 15, since the main scan 1 is set in the vertical region 83, the vertical movable center of the scanner 25 is the vertical region 83, and the angle ( The angle a) in FIG. 6 is 1 degree.

  In step S53, the control circuit 21 performs a filtering process. The filtering process of the control circuit 21 will be described in detail with reference to the flowchart of FIG.

  In step S <b> 71, the control circuit 21 reads the previous short-term optical axis deviation correction amount from the memory 31. In step S72, the control circuit 21 determines the value of the previous short-term optical axis deviation correction amount × 0.8 (80% of the previous short-term optical axis deviation correction amount) and the current optical axis deviation amount × 0.2. The sum of the values (20% of the current optical axis deviation amount) is calculated and set as the short-term optical axis deviation correction amount. For example, when the previous short-term optical axis deviation correction amount is 2 degrees and the current optical axis deviation amount is 1 degree, the short-term optical axis deviation correction amount is set to 1.8 degrees.

  After the process of step S72 of FIG. 17, the control circuit 21 advances the process to step S54 of FIG. 16, and performs a clipping process. This clipping process will be described in detail with reference to the flowchart of FIG.

  In step S <b> 91, the control circuit 21 reads the previous short-term optical axis deviation correction amount (stored in the previous step S <b> 55 described later) from the memory 31. In step S92, the control circuit 21 determines the difference between the current short-term optical axis deviation correction amount (short-term optical axis deviation correction amount set in step S72 in FIG. 17) and the previous short-term optical axis deviation correction amount. It is determined whether the absolute value is 1 degree or more. When it is determined that the absolute value of the difference between the current and previous short-term optical axis misalignment correction amounts is 1 degree or more, the control circuit 21 advances the process to step S93 and sets the current short-term optical axis misalignment correction amount. The value is changed to a value obtained by adding once to the previous optical axis deviation correction amount. With this process, the current short-term optical axis deviation correction amount is set to a value that is at most one degree larger than the previous optical axis deviation correction amount.

  When it is determined in step S92 that the absolute value of the difference between the current and previous short-term optical axis deviation correction amounts is not more than once (less than 1 degree), the control circuit 21 determines the short-term optical axis deviation correction amount. The value is left unchanged.

  After determining that the absolute value of the difference between the current and previous short-term optical axis misalignment correction amounts is not more than 1 degree in step S93 in FIG. 18 or in step S92, the control circuit 21 performs the process in FIG. Proceeding to step S55, the short-term optical axis deviation correction amount is stored in the memory 31.

  After the process of step S55 in FIG. 16, the control circuit 21 advances the process to step S28 in FIG. 10, reads the short-term optical axis deviation correction amount stored in the memory 31, and sets it as the optical axis deviation correction amount. When the process returns from step S37 to step S23, the vertical position of the scan range is corrected based on the set optical axis deviation correction amount. In step S29, the control circuit 21 determines whether or not the optical axis deviation correction amount satisfies the statistical target condition.

  FIG. 19 shows an example of the condition of the statistical object. The first condition is that “the distance from the preceding vehicle is 30 to 100 m”. If the distance satisfies this condition, the vehicle is traveling along a fixed distance. The second condition is that the absolute value of the optical axis deviation correction amount is within 2 degrees. This is a condition for excluding the influence of the instantaneous optical axis deviation. The third condition is that the host vehicle speed is 60 km / h or more. This is because the optical axis misalignment time due to hills is longer at low speeds when stopping and at low speeds, so it is a condition mainly for automobile roads and highways with little slope slope (short-term light To reduce the effects of shaft misalignment).

  If it is determined in step S29 that the optical axis misalignment correction amount satisfies all the conditions of the statistical target as shown in FIG. 19, the control circuit 21 advances the process to step S30 and sets the set light Add the axis offset correction amount to the histogram. That is, when a histogram as shown in FIG. 11 is stored in the memory 31 and the optical axis deviation correction amount is −1 degree, the number of corrections when the optical axis deviation correction amount of the histogram is −1 degree is 40. It is updated from 41 times to 41 times.

  In step S29, if there is a condition that does not satisfy any one of the three conditions of the statistical target, the process of step S30 is skipped. That is, the optical axis deviation correction amount is not added to the histogram. Accordingly, it is possible to suppress a long-term value of the optical axis deviation described later from being adversely affected based on an abnormal value such as an instantaneous optical axis deviation.

  In step S26, when it is determined that the preceding vehicle cannot be detected (for example, the maximum light reception amount is smaller than the reference value), the control circuit 21 advances the processing to step S31, and whether or not the statistical number of histograms is less than 1000. Determine whether. If it is determined that the number of statistics in the histogram is less than 1000, the control circuit 21 advances the process to step S32, and the long-term optical axis deviation correction amount (stored in step S113 in FIG. 20 described later) is stored in the memory 31. It is determined whether or not it is stored. If it is determined that the long-term optical axis deviation correction amount is not stored in the memory 31, the control circuit 21 advances the process to step S <b> 33 and sets a predetermined value (in the memory 31) as the optical axis deviation correction amount. Is stored).

  If it is determined in step S31 that the statistical number of histograms is not less than 1000 (1000 or more), the control circuit 21 advances the processing to step S34 and calculates a long-term optical axis deviation correction amount. The process in which the control circuit 21 calculates the long-term optical axis deviation correction amount will be described with reference to the flowchart of FIG.

  In step S111, the control circuit 21 detects from the histogram the optical axis misalignment correction amount with the largest number of corrections. For example, in the case of the example in which the histogram is shown in FIG. 11, an optical axis deviation correction amount of 0 degrees with the number of corrections being 100 is detected as the optical axis deviation correction amount with the largest number of corrections. In step S112, the control circuit 21 sets the optical axis misalignment correction amount (in this case, 0 degree) as the long-term optical axis misalignment correction amount. In step S <b> 113, the control circuit 21 stores the long-term optical axis deviation correction amount in the memory 31.

  After the process of step S113 of FIG. 20, the control circuit 21 advances the process to step S35 of FIG. 10, and reduces the statistical number of histograms by half. For example, the number of corrections for each optical axis deviation correction amount is all set to a half value. If it is determined that the long-term optical axis deviation correction amount is stored in the memory 31 after the process of step S35 or the process of step S32, the control circuit 21 advances the processing to step S36, and the optical axis deviation correction amount. A long-term optical axis deviation correction amount is set as follows. That is, the new long-term optical axis deviation correction amount set in the process of step S112 in FIG. 20 or the long-term optical axis deviation correction amount stored in the memory 31 in the previous process of step S113 in FIG. The optical axis deviation correction amount is set.

  In this way, 1000 optical axis misalignment correction amounts are added to the histogram by the process of step S30, and after the long-term optical axis misalignment correction amount is set by step S34, the number of statistics is 500 by the process of step S30. Each time the control circuit 21 is added, the control circuit 21 performs steps S34 to S36, determines a new long-term optical axis deviation correction amount, and sets the optical axis deviation correction amount.

  If it is determined in step S29 that the condition of the statistical target is not satisfied, after the process of step S30, the process of step S33, or the process of step S36, the control circuit 21 moves the process to step S37. Then, it is determined whether or not to end the laser radar process according to a user command. If it is determined that the laser radar processing has not yet ended, the control circuit 21 returns the processing to step S23 and corrects the optical axis based on the set optical axis deviation correction amount. That is, when the preceding vehicle is detected, the optical axis is corrected based on the short-term optical axis deviation correction amount, and when the preceding vehicle is not detected and the statistical number of histograms is 1000 or more, the long-term optical axis is detected. The optical axis is corrected based on the deviation correction amount. If the preceding vehicle is not detected and the number of statistics in the histogram is less than 1000, if the previous long-term optical axis deviation correction amount is not stored in the memory 31, the optical axis is based on the specified value. It is corrected. When the previous long-term optical axis deviation correction amount is stored, the optical axis is corrected based on the previous long-term term axis deviation correction amount. The above process is repeated until the end of the laser radar process is commanded.

  If it is determined in step S37 that the laser radar process is to be terminated, the control circuit 21 terminates the process.

  As described above, in the present invention, the optical axis shift is corrected so that the vertical region where the amount of received light is the maximum is the center in the vertical direction of the scan range. Even when the optical axis is deviated for several seconds due to the movement of the preceding vehicle in the vertical direction, the optical axis can be set to the optimum position, and the distance to be detected can be reliably measured. Further, since filtering processing and clipping processing are performed, it is possible to reduce the influence of the amount of received light due to instantaneous optical axis deviation and to obtain a more accurate correction amount.

  Even when there is no detection target, the optical axis deviation correction amount can be determined based on the optical axis deviation correction amount corrected so far and the histogram of the number of corrections. It is possible to correct a vertical tilt due to a change and a long-term optical axis shift due to a light collision or the like.

  The optical axis described in the above description means the center in the vertical direction of the scan range, and does not mean the front of the radar.

  In the above description, the case of detecting a vehicle has been described as an example. However, the present invention can also be applied to the case of detecting an obstacle and other objects.

  Note that the steps of executing the series of processes described above in this specification are performed in parallel or individually even if they are not necessarily processed in time series, as well as processes performed in time series in the order described. The processing to be performed is also included.

It is a figure which shows the use condition of one Embodiment of the laser radar system for vehicles to which this invention is applied. It is a block diagram which shows the structure of the laser radar of the vehicle of FIG. It is a block diagram which shows the structure which supports the light projection lens and light receiving lens of FIG. It is a figure which shows the optical path of the laser beam of the laser radar of FIG. It is a figure which shows the detection area in the horizontal surface of the laser radar of FIG. It is a figure which shows the detection area in the vertical plane of the laser radar of FIG. It is a figure which shows the scanning direction of the laser radar of FIG. It is a figure which shows the scanning order of the laser radar of FIG. 3 is a flowchart for explaining processing for correcting the vertical optical axis by the control circuit of FIG. 2. 3 is a flowchart for explaining processing for correcting the vertical optical axis by the control circuit of FIG. 2. It is a figure which shows the example of the histogram of an optical axis shift | offset | difference correction amount and the frequency | count of correction | amendment. It is a figure which shows the example of the area | region which the scanner of FIG. 2 scans. It is a figure which shows the example of the area | region which the scanner of FIG. 2 scans. It is a figure which shows the example of the area | region which the scanner of FIG. 2 scans. It is a figure which shows the example of the light reception amount corresponding to an area | region. 10 is a flowchart for explaining short-term optical axis deviation correction amount determination processing in step S27 of FIG. 9. It is a flowchart explaining the filtering process of step S53 of FIG. It is a flowchart explaining the clipping process of step S54 of FIG. It is a figure which shows the example of the conditions added to the histogram of FIG. It is a flowchart explaining the long-term optical axis deviation correction amount determination process of step S34 of FIG.

Explanation of symbols

11, 12 Vehicle 20 Laser radar 21 Control circuit 22 LD drive circuit 23 LD
24 Projection lens 25 Scanner 26 Vertical scanning position detection device 27 Horizontal scanning position detection device 28 Light receiving lens 29 PD
DESCRIPTION OF SYMBOLS 30 Light reception circuit 31 Memory 32 Vehicle measurement sensor 41 Drive circuit 42 Horizontal direction drive coil 43 Horizontal direction leaf | plate spring 44 Vertical direction drive coil 45 Vertical direction leaf | plate spring 51 Support member

Claims (10)

In an object detection device that emits an electromagnetic wave in the traveling direction of the vehicle and detects an object based on a reflected wave of the electromagnetic wave,
Emitting means for emitting the electromagnetic wave while scanning in a scanning range in a horizontal direction and a vertical direction;
Receiving means for receiving the reflected wave of the electromagnetic wave;
Obtaining means for obtaining the level of the reflected wave received by the receiving means;
A calculation means for calculating a first deviation correction amount based on a vertical position of a region where the level of the reflected wave is maximum and a vertical center position of the scan range;
Correction means for correcting the position of the center in the vertical direction of the scan range based on the first deviation correction amount calculated by the calculation means, and measuring the distance from the object by the reflected wave. ,
The emitting means scans in a first direction which is a predetermined direction in the horizontal direction in a central region centered on a vertical center of the scan range, and in a region above the central region, A first scanning process for emitting while scanning in a second direction opposite to the first direction; scanning in the first direction in the central region; and the first scanning process in a region below the central region. And a second scan process for emitting the light while scanning in the direction of 2. A first holding means for holding the first deviation correction amount for each scan of the scan range;
The said calculating means calculates the said 1st shift correction amount of the next time according to the said 1st shift correction amount of the last time hold | maintained by the said 1st holding means. Object detection device. The computing means, when the difference between the previous first deviation correction amount held by the first holding means and the next first deviation correction amount is equal to or greater than a predetermined value, The object detection apparatus according to claim 2, wherein the deviation correction amount is determined as a sum of the previous first deviation correction amount and the predetermined value. Storage means for storing a histogram of the first deviation correction amount and the number of times the position has been corrected by the correction means;
2. The object detection device according to claim 1, wherein when the first deviation correction amount satisfies a predetermined condition, 1 is added to the number of corrections corresponding to the first deviation correction amount of the histogram. . The condition is that the distance between the vehicle and the object is within a predetermined range, the absolute value of the first deviation correction amount is within a predetermined value, and the speed of the vehicle is greater than or equal to a predetermined value. The object detection apparatus according to claim 4. First determination means for determining whether or not the object is detected;
Second determination means for determining whether or not the statistical number of the histogram is greater than a predetermined reference value when it is determined by the first determination means that the object is not detected;
When the second determination means determines that the statistical number of the histogram is greater than the reference value, the first shift correction amount with the largest number of corrections of the histogram is set as a second shift correction amount. And a setting means,
The object detection apparatus according to claim 4, wherein the correction unit further corrects a vertical center position of the scan range based on the second displacement correction amount. Second holding means for holding the second deviation correction amount;
A third determination unit that determines whether or not the second shift correction amount is held by the second holding unit;
When the third determination unit determines that the second deviation correction amount is held, the correction unit determines the center of the scan range in the vertical direction based on the second deviation correction amount. The position of the object detection device according to claim 6, wherein the position is corrected. When it is determined by the third determination means that the second deviation correction amount is not held, the correction means determines the center of the scan range in the vertical direction based on the preset deviation correction amount. The position of the object detection device according to claim 6, wherein the position is corrected. Based on the level of the reflected wave acquired by the acquisition means, further comprising a determination means for determining whether a preceding vehicle has been detected;
When the determination means determines that the preceding vehicle has been detected by the determination means, the calculation means is based on the vertical position of the region where the level of the reflected wave is maximum and the vertical center position of the scan range. The object detection device according to claim 1, wherein the first deviation correction amount is calculated. In an object detection method of an object detection device that emits an electromagnetic wave toward a traveling direction of a vehicle and detects an object based on a reflected wave of the electromagnetic wave,
An emission step of emitting the electromagnetic wave while scanning in a scan range in a horizontal direction and a vertical direction;
Receiving the reflected wave of the electromagnetic wave;
An acquisition step of acquiring a level of the reflected wave received by the processing of the reception step;
A calculation step of calculating a first deviation correction amount based on a vertical position of an area where the level of the reflected wave is maximum and a vertical center position of the scan range;
A correction step of correcting the position of the center of the scan range in the vertical direction based on the first shift correction amount calculated by the processing of the calculation step, and measuring the distance from the object by the reflected wave; Including
In the process of the emission step, a scan is performed in a first direction which is a predetermined direction in a horizontal direction in a center area centered on a vertical center position of the scan range, and an area above the center area In the first scanning process of emitting while scanning in a second direction opposite to the first direction, and scanning in the first direction in the central region, in the region below the central region And a second scanning process of emitting while scanning in the second direction.

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