JP2016044985A - Laser radar device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the detecting accuracy of laser radar devices.SOLUTION: If it is determined at step S152 that the intensity of the reflected light in every direction is at or above a prescribed threshold, at step S153 that the differences in detection distance among different directions are within a prescribed range, and at step S156 the difference in normalization received light value between the latest and immediate preceding occasions is within a prescribed range, the update counter is incremented at step S158. If at step S159 it is determined that the update counter has surpassed a threshold, at step S160 correction coefficients for correcting the received light values of different light receiving elements are updated on the basis of the normalization received light value of each light receiving element. This device is applicable to, for instance, laser radar devices for on-vehicle use.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a laser radar device, and more particularly to a laser radar device that improves the detection accuracy of an object.

  Conventionally, measurement light, which is pulsed laser light, is projected onto a predetermined monitoring area, and reflected light from a plurality of directions is simultaneously received by a plurality of light receiving elements. 2. Description of the Related Art A vehicle-mounted distance measuring sensor that obtains a distance from an object such as a road surface or a vehicle based on a period until the light is received is known.

  For example, Patent Document 1 discloses a technique relating to calibration for maintaining detection accuracy because the characteristics of a CCD sensor used in a light receiving element change depending on the outside air temperature or the like. For example, calibration is permitted when the variance in luminance detected by each pixel of reflected light from the road surface is equal to or less than a predetermined threshold. Then, it is disclosed that the detected distance is calibrated using a reference distance calculated in advance by the geometric relationship between the distance image sensor and the road surface.

JP 2010-151680 A

  However, since the reflected light from the road surface is weak, the value of the light reception signal (light reception value) output from each light receiving element is also lowered, and as a result, the accuracy of the distance to the detected road surface is deteriorated. Therefore, there is a concern that the calibration performed based on the reflected light from the road surface cannot be accurately calibrated.

  Another problem is that the distance calculated in advance based on the geometric relationship between the reference distance image sensor and the road surface changes depending on the accuracy of the assembly of the distance image sensor mounted on the vehicle.

  Therefore, the present invention is to improve the detection accuracy of the laser radar device. In particular, the detection accuracy of the laser radar apparatus is improved by performing correction based on reflected light from an object that can be regarded as having uniform reflection.

  A laser radar device according to one aspect of the present invention includes a light projecting unit that intermittently projects measurement light that is pulsed laser light, and a plurality of light receiving elements that receive reflected light of the measurement light reflected by an object. , By performing sampling of light reception signals from each light receiving element at a plurality of sampling times, a measurement unit for measuring the light reception value of each light receiving element, and a correction coefficient for setting a correction coefficient for correcting the light reception value of each light receiving element The correction unit includes a setting unit, a correction unit that corrects the light reception value of each light receiving element using a correction coefficient, and an object detection unit that measures a distance from the object based on the corrected light reception value. The first condition that the time difference between the sampling times when the light receiving value of each light receiving element reaches a peak is within the first predetermined range, and the second condition that the object can be regarded as having a surface with uniform reflection characteristics. If satisfied, correct To set the number.

  In the laser radar device according to the first aspect of the present invention, the measurement light, which is pulsed laser light, is intermittently projected, and the reflected light of the measurement light reflected by the object is received. By performing the sampling of the received light signal at a plurality of sampling times, the received light value of each light receiving element is measured, and the correction coefficient for correcting the received light value of each light receiving element is set. The received light value is corrected, the distance from the object is measured based on the corrected received light value, and the time difference between the sampling times at which the received light value of each light receiving element peaks is within a first predetermined range. The correction coefficient is set when the condition and the second condition that allows the object to be regarded as having a surface with uniform reflection characteristics are satisfied.

  Therefore, the detection accuracy of the laser radar device can be improved.

  For example, the light projecting unit includes a drive circuit, a light emitting element, a light projecting optical system, and the like. This light receiving element is formed of, for example, a photodiode. This measurement part is comprised by AD converter etc., for example. The correction coefficient setting unit, the correction unit, and the object detection unit are configured by an arithmetic device such as a microcomputer and various processors, for example.

  The second condition can be that the variation of the peak value of the light receiving value of each light receiving element is within the second predetermined range.

  Thereby, a more appropriate correction coefficient can be set.

  When the first condition and the second condition are satisfied, a storage unit for storing the peak value of the light reception value of each light receiving element is further provided, and the peak value of the light reception value stored last time and the current light reception value are determined based on the second condition. The difference when the difference from the peak value is calculated for each light receiving element can be within the third predetermined range.

  Thereby, a more appropriate correction coefficient can be set.

  When the first condition and the second condition are satisfied, a storage unit for storing the peak value of the light receiving value of each light receiving element is further provided, and the correction coefficient setting unit includes the number of times the first condition and the second condition are satisfied. Can be set using a plurality of received light values stored for each light receiving element.

  Thereby, a more appropriate correction coefficient can be set.

  A luminance distribution determination unit that determines whether the luminance distribution of the object that reflects the measurement light is smooth based on an image acquired by an image sensor that captures the direction in which the measurement light is projected is provided. The second condition may be that the luminance distribution determining unit determines that the luminance of the object is smooth.

  Thereby, a more appropriate correction coefficient can be set.

  The luminance distribution determination unit is configured by an arithmetic device such as a microcomputer and various processors, for example.

  The correction coefficient setting unit can set a correction coefficient based on a normalized light reception value obtained by normalizing each light reception peak value with the maximum value of the light reception peak values of all the light receiving elements.

  Thereby, a more appropriate correction coefficient can be set.

  According to the present invention, the detection accuracy of a laser radar device can be improved.

1 is a block diagram showing a first embodiment of a laser radar device to which the present invention is applied. It is a block diagram which shows the structural example of a measurement light projector. It is a block diagram which shows the structural example of a light-receiving part. It is a figure which shows the position of each detection area typically. It is a schematic diagram which shows the relationship between each light receiving element and each detection area. It is a block diagram which shows the structural example of a measurement part. It is a block diagram which shows 1st Embodiment of the structural example of the function of a calculating part. It is a flowchart for demonstrating a correction coefficient adjustment process. It is a timing chart for demonstrating the sampling process of a received light signal. It is a flowchart for demonstrating a monitoring process. It is a flowchart for demonstrating 1st Embodiment of a correction coefficient update process. It is a flowchart for demonstrating 2nd Embodiment of a correction coefficient update process. It is a figure for demonstrating the example of the detection method of a vehicle. It is a block diagram which shows 2nd Embodiment of the laser radar apparatus to which this invention is applied. It is a block diagram which shows 2nd Embodiment of the structural example of the function of a calculating part. It is a flowchart for demonstrating 3rd Embodiment of a correction coefficient update process. It is a block diagram which shows the structural example of a computer.

Hereinafter, modes for carrying out the present invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. First Embodiment 2. FIG. Second Embodiment 3. FIG. Modified example

<1. First Embodiment>
First, a first embodiment of the present invention will be described with reference to FIGS.

{Configuration example of laser radar device 11}
FIG. 1 shows a configuration example of a laser radar apparatus 11 which is a first embodiment of a laser radar apparatus to which the present invention is applied.

  The laser radar device 11 is provided in a vehicle, for example, and monitors the front of the vehicle. Hereinafter, an area in which an object can be detected by the laser radar device 11 is referred to as a monitoring area. Hereinafter, when it is necessary to distinguish a vehicle provided with the laser radar device 11 from other vehicles, the vehicle is referred to as a host vehicle. Further, hereinafter, a direction parallel to the left-right direction (vehicle width direction) of the host vehicle is referred to as a horizontal direction.

  The laser radar device 11 is configured to include a control unit 21, a measurement light projecting unit 22, a light receiving unit 23, a measurement unit 24, and a calculation unit 25.

  The control unit 21 controls each unit of the laser radar device 11 based on commands and information from the vehicle control device 12.

  The measurement light projector 22 projects measurement light, which is pulsed laser light (laser pulse) used to detect an object, onto the monitoring area.

  The light receiving unit 23 receives the reflected light of the measurement light and detects the intensity (brightness) of the reflected light from different directions in the horizontal direction. And the light-receiving part 23 outputs the some light reception signal which is an electrical signal according to the intensity | strength of the reflected light of each direction.

  The measurement unit 24 measures the light reception value with respect to the reflected light based on the light reception signal supplied from the light reception unit 23 and supplies the measurement result to the calculation unit 25.

  The calculation unit 25 detects an object in the monitoring area based on the measurement result of the received light value supplied from the measurement unit 24 and supplies the detection result to the control unit 21 and the vehicle control device 12.

  The vehicle control device 12 is configured by, for example, an ECU (Electronic Control Unit) or the like, and performs automatic brake control, a warning to the driver, or the like based on the detection result of the object in the monitoring area.

{Configuration example of measuring light projector 22}
FIG. 2 shows a configuration example of the measurement light projector 22 of the laser radar device 11. The measuring light projecting unit 22 is configured to include a drive circuit 101, a light emitting element 102, and a projecting optical system 103.

  The drive circuit 101 controls the light emission intensity and the light emission timing of the light emitting element 102 under the control of the control unit 21.

  The light emitting element 102 is made of, for example, a laser diode, and emits measurement light (laser pulse) under the control of the drive circuit 101. The measurement light emitted from the light emitting element 102 is projected onto the monitoring area via the light projecting optical system 103 constituted by a lens or the like.

{Configuration example of light receiving unit 23}
FIG. 3 shows a configuration example of the light receiving unit 23 of the laser radar device 11. The light receiving unit 23 is configured to include a light receiving optical system 201 and light receiving elements 202-1 to 202-16.

  Hereinafter, the light receiving elements 202-1 to 202-16 are simply referred to as the light receiving elements 202 when it is not necessary to distinguish them individually.

  The light receiving optical system 201 is configured by a lens or the like, and is installed so that the optical axis faces the front-rear direction of the vehicle. The light receiving optical system 201 receives the reflected light of the measurement light reflected by an object or the like in the monitoring area, and makes the reflected light incident on the light receiving surface of each light receiving element 202.

  Each light receiving element 202 is composed of, for example, a photodiode that photoelectrically converts incident photoelectric charges into a received light signal having a current value corresponding to the amount of light. Each light receiving element 202 is perpendicular to the optical axis of the light receiving optical system 201 and parallel to the vehicle width direction of the host vehicle (that is, horizontal) at the position where the reflected light incident on the light receiving optical system 201 is collected. In the direction). Then, the reflected light incident on the light receiving optical system 201 is distributed and incident on each light receiving element 202 according to the incident angle in the horizontal direction to the light receiving optical system 201. Therefore, each light receiving element 202 receives reflected light from different directions in the horizontal direction among the reflected light from the monitoring region. Thereby, the monitoring area is divided into a plurality of areas (hereinafter referred to as detection areas) in a plurality of horizontal directions, and each light receiving element 202 individually receives the reflected light from the corresponding detection area. The light receiving element 202 photoelectrically converts the received reflected light into a light reception signal having a current value corresponding to the amount of light received, and supplies the obtained light reception signal to the measurement unit 24.

  Here, a specific example of the detection region of each light receiving element 202 will be described with reference to FIGS. 4 and 5. FIG. 4 schematically shows the position of each detection region when the host vehicle C provided with the laser radar device 11 is viewed from above. FIG. 5 schematically shows the relationship between each light receiving element 202 and each detection region when the light receiving unit 23 is viewed from above. In FIG. 5, only the light rays passing through the center of the lens of the light receiving optical system 201 out of the reflected light from each detection region are schematically shown for easy understanding of the drawing.

  The light receiving elements 202 are arranged in a line in the order of the light receiving elements 202-1, 202-2, 202-3... From the right in the traveling direction of the host vehicle C. On the other hand, the monitoring area of the laser radar device 11 is composed of detection areas A1 to A16 that radiate in front of the host vehicle C, and each detection area is a detection area from the left in the traveling direction of the host vehicle C. A1, A2, A3... Are arranged in this order. The light receiving element 202-1 receives the reflected light from the detection area A1, which is the left end in the monitoring area and indicated by the oblique line on the left front of the host vehicle C. The light receiving element 202-16 receives reflected light from the detection area A16, which is the right end in the monitoring area and indicated by the oblique line in front of the right side of the host vehicle C. Furthermore, the light receiving elements 202-8 and 202-9 receive the reflected light from the detection areas A8 and A9 indicated by the hatching in the center of the monitoring area.

{Configuration example of measurement unit 24}
FIG. 6 shows a configuration example of the measurement unit 24 of the laser radar device 11. The measurement unit 24 is configured to include a current / voltage conversion unit 251, an amplification unit 252, and a sampling unit 253. The current-voltage converter 251 is configured to include trans-impedance amplifiers (TIAs) 261-1 to 261-16. The amplifying unit 252 is configured to include programmable gain amplifiers (PGA) 262-1 to 262-16. The sampling unit 253 is configured to include A / D converters (ADC) 263-1 to 263-16. In addition, the TIA 261-i, the PGA 262-i, and the ADC 263-i (i = 1 to 16) are connected in series.

  Hereinafter, when it is not necessary to individually distinguish TIA 261-1 through 261-16, PGA 262-1 through 262-16, and ADC 263-1 through 263-16, TIA 261, PGA 262, and ADC 263 are simply Called.

  Each TIA 261 performs current-voltage conversion of the light reception signal supplied from the light receiving element 202 under the control of the control unit 21. That is, each TIA 261 converts a received light signal as an input current into a received light signal as a voltage, and amplifies the voltage of the converted received light signal with a gain set by the control unit 21. Each TIA 261 supplies the amplified received light signal to the subsequent PGA 262.

  Under the control of the control unit 21, each PGA 262 amplifies the voltage of the light reception signal supplied from the TIA 261 with the gain set by the control unit 21, and supplies the amplified signal to the subsequent ADC 263.

  Each ADC 263 performs A / D conversion of the received light signal. That is, each ADC 263 measures the light reception value by sampling the analog light reception signal supplied from the PGA 262 under the control of the control unit 21. Each ADC 263 supplies a digital light reception signal indicating a sampling result (measurement result) of the light reception value to the arithmetic unit 25.

{Configuration example of calculation unit 25}
FIG. 7 shows a configuration example of the function of the calculation unit 25. The calculation unit 25 is configured to include a detection unit 301 and a notification unit 302. The detection unit 301 is configured to include a peak detection unit 311, a correction coefficient setting unit 312, a storage unit 313, a correction unit 314, and an object detection unit 315.

  The peak detection unit 311 detects the peak of the light reception value of each light receiving element 202. Thereby, the peak of the intensity | strength of the reflected light of measurement light in the horizontal direction and the time direction (distance direction) is detected. The peak detection unit 311 supplies the detection result to the correction coefficient setting unit 312 and the correction unit 314.

  The correction coefficient setting unit 312 calculates a correction coefficient for correcting the light reception value of each light receiving element 202 based on the detection result of the peak of the light reception value of each light receiving element 202 and stores the correction coefficient in the storage unit 313. Further, the correction coefficient setting unit 312 stores the result of detecting the peak of the light reception value of each light receiving element 202 in the storage unit 313 or reads out from the storage unit 313 as necessary.

  For example, even if incident light with the same intensity is incident on each light receiving element 202 at the same time, it is measured due to individual differences among the light receiving elements 202, TIA 261, PGA 262, and ADC 263, differences in circuit length and layout through which each light received signal flows, The received light value varies. The correction coefficient is a coefficient for correcting the variation in characteristics between the light receiving elements 202 so that the light receiving values of the light receiving elements 202 with respect to incident light having the same intensity become substantially the same value.

  The correction unit 314 corrects the received light value using the correction coefficient stored in the storage unit 313 for the detection result of the peak of the light reception value of each light receiving element 202, and the corrected detection result is used as the object detection unit. 315 is supplied.

  The object detection unit 315 detects an object in the monitoring area based on the detection result of the peak of the light reception value of each light receiving element 202 after correction, and supplies the detection result to the control unit 21 and the notification unit 302.

  The notification unit 302 supplies the detection result of the object in the monitoring area to the vehicle control device 12.

{Correction coefficient adjustment process}
Next, correction coefficient adjustment processing executed by the laser radar apparatus 11 will be described with reference to the flowchart of FIG. This process is executed, for example, when the laser radar device 11 is adjusted in a factory, a dealer, or the like before shipment of the vehicle provided with the laser radar device 11. At this time, for example, the laser radar device 11 is set to an operation mode (hereinafter referred to as an adjustment mode) different from a normal operation mode (hereinafter referred to as a normal mode).

  Moreover, this process is performed in the state in which the reference board was installed in front of the own vehicle, for example. This reference board has a reflective surface (for example, a white plate) composed of a surface having substantially uniform reflection characteristics, in other words, a surface having substantially the same reflection characteristics in each region. The reflection surface is substantially perpendicular to the optical axis of the measurement light projecting unit 22 (the traveling direction of the host vehicle), and all the measurement light projected from the laser radar device 11 is incident on the reflection surface. A reference board is installed.

  In step S <b> 1, the control unit 21 initializes each unit of the laser radar device 11.

  In step S <b> 2, the measurement light projector 22 projects measurement light. Specifically, the drive circuit 101 emits pulsed measurement light from the light emitting element 102 under the control of the control unit 21. The measurement light emitted from the light emitting element 102 is projected through the light projecting optical system 103 and is incident on the reflective surface of the reference board.

  At this time, since the reflection characteristics of the reflection surface of the reference board are substantially uniform, the horizontal direction of the intensity of the reflected light (for example, the brightness of the reflected light) reflected by the reflection surface toward the laser radar device 11 by the reflection surface The distribution of is almost smooth.

  For example, since the light projecting optical system 103 is not homogeneous in the horizontal direction, the measurement light may not be projected evenly on the entire reference board. However, in the present invention, correction can be performed including such variations.

  In step S3, the light receiving unit 23 generates a light reception signal corresponding to the reflected light. Specifically, each light receiving element 202 receives the reflected light from the detection area in the corresponding direction among the reflected light with respect to the measurement light projected in the process of step S <b> 2 via the light receiving optical system 201.

  At this time, the reflected light from the reference board enters all the light receiving elements 202, and the intensity of the reflected light incident on each light receiving element 202 (for example, the illuminance of the reflected light) becomes substantially equal.

  Each light receiving element 202 photoelectrically converts the received reflected light into a received light signal that is an electrical signal corresponding to the received light amount, and supplies the obtained received light signal to the TIA 261 at the subsequent stage.

  In step S4, the measurement unit 24 samples the received light signal. Specifically, each TIA 261 performs current-voltage conversion of the light reception signal supplied from each light receiving element 202 under the control of the control unit 21, and uses the gain set by the control unit 21 to change the voltage of the light reception signal. Amplify. Each TIA 261 supplies the amplified light reception signal to the subsequent PGA 262.

  Under the control of the control unit 21, each PGA 262 amplifies the voltage of the light reception signal supplied from each TIA 261 with the gain set by the control unit 21, and supplies the amplified signal to the subsequent ADC 263.

  Each ADC 263 performs sampling of the light reception signal supplied from each PGA 262 under the control of the control unit 21, and A / D converts the light reception signal. Each ADC 263 supplies the received light signal after A / D conversion to the peak detector 311.

  Here, a specific example of the sampling process of the received light signal will be described with reference to the timing chart of FIG.

  The exceptional horizontal axis in FIG. 9 indicates time. The first row shows the emission timing of the measurement light. The second row shows the waveform of the trigger signal that defines the sampling timing of the ADC 263. The third row shows the sampling timing of the received light signal in the ADC 263. The vertical axis in the third stage indicates the value (voltage) of the light reception signal, and a plurality of black circles on the light reception signal indicate sampling points, respectively. Therefore, the time between adjacent black circles is the sampling interval.

  The control unit 21 supplies a trigger signal to each ADC 263 after a predetermined time has elapsed since the measurement light projected intermittently. Each ADC 263 samples the received light signal a predetermined number of times (for example, 32 times) at a predetermined sampling frequency (for example, several tens of MHz to several GHz) after a predetermined time has elapsed since the trigger signal was input. That is, when the measurement light is projected once, the received light signal is sampled a predetermined number of times at a predetermined sampling interval.

  For example, if the sampling frequency of the ADC 263 is 600 MHz, sampling is performed at a sampling interval of about 1.67 nanoseconds. Therefore, the received light value is sampled at intervals of about 250 mm in terms of distance. That is, the intensity of the reflected light from each point at intervals of about 250 mm in the distance direction from the host vehicle in each detection region is measured. For example, when the sampling frequency of the ADC 263 is 6 GHz, sampling is performed at a sampling interval of about 0.167 nanoseconds. Therefore, the received light value is sampled at intervals of about 25 mm in terms of distance. That is, the intensity of the reflected light from each point at an interval of about 25 mm in the distance direction from the host vehicle in each detection region is measured.

  Each ADC 263 supplies a digital light reception signal indicating a sampling value (light reception value) at each sampling time with the trigger signal as a reference (the time when the trigger signal is input is 0) to the peak detection unit 311.

  In step S5, the peak detection unit 311 performs peak detection. Specifically, the peak detection unit 311 detects a sampling time (hereinafter referred to as peak time) at which the light reception value of each light receiving element 202 reaches a peak, and a light reception value at the peak time (hereinafter referred to as a light reception peak value). . The peak detector 311 converts the time (Time of Flight) from the measurement light projection time to the peak time of the light reception value of each light receiving element 202 into a distance (hereinafter referred to as a detection distance).

  This detection distance represents a distance from the host vehicle to a position where the intensity of reflected light peaks in each detection area, that is, a position where there is a high possibility that an object to be detected exists in each detection area. Therefore, when the reference board is properly installed in front of the vehicle and the laser radar device 11 is operating normally, the detection distance and the light reception peak value of each detection region (each light receiving element 202) are substantially equal. . In addition, the distribution of the received light peak value in the horizontal direction is almost smooth.

  Then, the peak detection unit 311 supplies the detection distance of each detection region and the detection result of the received light peak value to the correction coefficient setting unit 312.

  In step S6, the correction coefficient setting unit 312 determines whether or not the intensity of reflected light in all directions is equal to or greater than a predetermined threshold. The correction coefficient setting unit 312 determines that the reflected light intensity in all directions is equal to or greater than the predetermined threshold when the light reception peak values of all the light receiving elements 202 are equal to or greater than the predetermined threshold, and the process proceeds to step S7. .

  Note that the threshold value used in this process is set to the same value as the threshold value used for determining the presence or absence of an object in each detection region, for example.

  In step S <b> 7, the correction coefficient setting unit 312 determines whether or not the difference between the detection distances in the respective directions is within a predetermined range. The correction coefficient setting unit 312 calculates the difference between the minimum value and the maximum value in the detection distance of each detection region, and when the condition that the calculated distance difference is within a predetermined threshold is satisfied, It is determined that the difference is within the predetermined range, and the process proceeds to step S8.

  In step S8, the correction coefficient setting unit 312 normalizes the received light peak value. Specifically, the correction coefficient setting unit 312 divides the light reception peak value of each light receiving element 202 by the maximum value of the light reception peak values of all the light receiving elements 202 to obtain a normalized light reception peak value (hereinafter referred to as normalized light reception). (Referred to as value).

  In step S9, the correction coefficient setting unit 312 calculates a correction coefficient based on the normalized received light value. For example, the correction coefficient setting unit 312 sets the normalized light reception value of each light receiving element 202 as it is as the correction coefficient of each light receiving element 202. Then, the correction coefficient setting unit 312 stores the set correction coefficient of each light receiving element 202 in the storage unit 313. Thereafter, the correction coefficient adjustment process ends.

  The normalized light receiving value indicates the ratio of the light receiving peak value of each light receiving element 202 to the maximum value of the light receiving peak values of all light receiving elements 202, and the ratio of the light receiving value of each light receiving element 202 to the reflected light of the same intensity is The ratio of the normalized light receiving values of the light receiving elements 202 is substantially equal. Then, by dividing the light receiving value of each light receiving element 202 by the corresponding correction coefficient (= normalized light receiving value), the light receiving value of each light receiving element 202 with respect to the reflected light of the same intensity becomes substantially equal. Variations in received light values are corrected.

  On the other hand, in step S7, when the difference between the minimum value and the maximum value in the detection distance of each detection region exceeds a predetermined threshold value, the correction coefficient setting unit 312 sets the difference in the detection distance in each direction within a predetermined range. Judge that it has exceeded. Then, the processes in steps S8 and S9 are skipped, and the correction coefficient adjustment process ends.

  In step S6, the correction coefficient setting unit 312 determines that there is a direction in which the intensity of the reflected light is less than the predetermined threshold when the light reception peak value of at least one light receiving element 202 is less than the predetermined threshold. Then, the processes in steps S7 to S9 are skipped, and the correction coefficient adjustment process ends.

  That is, in any of the above cases, the correction coefficient adjustment process is terminated without setting the correction coefficient. For example, a case where a reference board is not properly installed or an abnormality occurs in the laser radar device 11 is assumed.

  Thus, for example, workers in factories, dealers, and the like install a reference board in front of the host vehicle, set the laser radar device 11 to the adjustment mode, and operate according to individual differences of each component. The correction coefficient can be set easily and appropriately.

{Monitoring process}
Next, the monitoring process executed by the laser radar device 11 will be described with reference to the flowchart of FIG. Note that this processing is started when, for example, an ignition switch or a power switch of a vehicle provided with the laser radar device 11 is turned on, and is ended when the vehicle is turned off.

  In addition, when the correction coefficient adjustment process described above with reference to FIG. 8 is performed before this monitoring process, the correction coefficient of each light receiving element 202 obtained as a result of the process is stored in the storage unit 313. It becomes. On the other hand, when the correction coefficient adjustment process is not executed before this monitoring process, the initial value of the correction coefficient of each light receiving element 202 is stored in the storage unit 313. The initial values are all set to 1, for example.

  In steps S101 to S105, processing similar to that in steps S1 to S5 of FIG. 8 described above is performed. That is, after the laser radar device 11 is initialized, measurement light is projected, reflected light with respect to the measurement light is received, a received light signal corresponding to the reflected light is generated, and the received light signal is sampled. Then, the detection distance of each detection region and the light reception peak value of each light receiving element 202 are detected, and the detection result is supplied to the correction coefficient setting unit 312 and the correction unit 314.

  In step S106, the correction coefficient setting unit 312 performs a correction coefficient update process. Here, the details of the correction coefficient update processing will be described with reference to the flowcharts of FIGS. 11 and 12. First, the first embodiment of the correction coefficient update process will be described with reference to the flowchart of FIG.

  In step S151, the correction coefficient setting unit 312 determines whether or not the value of the correction coefficient update lock flag is set to 0. The value of the correction coefficient update lock flag is set to 0 or 1, and when it is set to 0, update of the correction coefficient is permitted, and when it is set to 1, update of the correction coefficient is prohibited. In the initial state, the value of the correction coefficient update flag is set to 0. When it is determined that the value of the correction coefficient update lock flag is set to 0, that is, when update of the correction coefficient is permitted, the process proceeds to step S152.

  In step S152, as in the process of step S6 in FIG. 8, it is determined whether or not the intensity of reflected light in all directions is equal to or greater than a predetermined threshold, and the intensity of reflected light in all directions is equal to or greater than a predetermined threshold. If determined to be, the process proceeds to step S153.

  In step S153, as in the process of step S7 in FIG. 8, it is determined whether or not the difference in detection distance in each direction is within a predetermined range, and the difference in detection distance in each direction is in the predetermined range. If determined to be, the process proceeds to step S154.

  This is the case where there is an object that reflects the measurement light at substantially the same distance across all detection areas. For example, like the reference board described above, it has a wide surface that faces in a direction substantially perpendicular to the optical axis (traveling direction of the host vehicle) of the measurement light projecting unit 22 and that allows all measurement light to enter. This is a case where an object (for example, a large vehicle such as a truck, a wall, a fence, etc.) exists.

  In step S154, the received light peak value is normalized in the same manner as in step S8 of FIG.

  In step S155, the correction coefficient setting unit 312 calculates the difference between the current and previous normalized light reception values. Specifically, the correction coefficient setting unit 312 reads the previous normalized light reception value of each light receiving element 202 from the storage unit 313. The previous normalized light reception value is a normalized light reception value calculated at the closest time from the current time and stored in the storage unit 313. Then, the correction coefficient setting unit 312 calculates the absolute value of the difference between the current normalized light reception value calculated in step S154 and the previous normalized light reception value (hereinafter referred to as the difference light reception value) for each light receiving element 202. To calculate.

  In step S156, the correction coefficient setting unit 312 determines whether or not the difference between the current and previous normalized light reception values is within a predetermined range. Specifically, the correction coefficient setting unit 312 compares the light reception difference value of each light receiving element 202 with a predetermined threshold value, and when all the light reception difference values are equal to or less than the threshold value, the difference between the current and previous normalized light reception values. Is determined to be within a predetermined range. This is a case where the distribution of the normalized light receiving values of the respective light receiving elements 202 this time is similar to the distribution of the normalized light receiving values of the respective light receiving elements 202 of the previous time.

  Note that the threshold used in this determination process may be set to the same value for all the light receiving elements 202 or may be set to a different value for each light receiving element 202.

  In step S157, the correction coefficient setting unit 312 increments the update counter. That is, this update counter is incremented when the distribution of the current normalized light reception value is similar to the distribution of the previous normalized light reception value. Therefore, the value of the update counter increases as the number of times an object having a similar distribution of normalized light reception values appears in front of the host vehicle increases.

  Here, an object that satisfies the determination condition of step S156, that is, an object with a similar distribution of normalized light reception values, is directed substantially perpendicular to the optical axis of the measurement light projecting unit 22, and all of the measurement light is present. It is assumed that the object has a wide surface that is incident and has a surface with substantially uniform reflection characteristics. As such a surface, for example, a wall, a bag, a rear surface of a large vehicle, etc., of which the entire surface is substantially the same color are assumed. On the other hand, there are very rare cases where the distribution of normalized light reception values is similar between objects that do not have a surface with substantially uniform reflection characteristics. Therefore, the process of step S156 is a process of determining whether or not the detected object (an object existing at substantially the same distance across all detection areas) can be regarded as having a surface with substantially uniform reflection characteristics. It can be said.

  In addition, it is assumed that the horizontal distribution of the received light peak value with respect to the reflected light from such a surface is substantially smooth. Here, being almost smooth means that there is little variation in the light receiving peak value of each light receiving element 202.

  Note that there is a variation in the characteristics between the light receiving elements 202, and even if the horizontal distribution of the received light peak value with respect to the reflected light from the surface having a uniform reflection characteristic is not smooth, There is almost no difference. Therefore, an object having a surface with substantially uniform reflection characteristics can be detected by the determination processing in step S156.

  In step S158, the correction coefficient setting unit 312 determines whether or not the update counter exceeds a predetermined threshold value. If it is determined that the update counter exceeds the predetermined threshold, the process proceeds to step S159.

  In step S159, the correction coefficient setting unit 312 updates the correction coefficient. For example, the correction coefficient setting unit 312 sets the normalized light reception value of each light receiving element 202 this time as a new correction coefficient of each light receiving element 202 as in the process of step S9 in FIG. Then, the correction coefficient setting unit 312 stores the newly set correction coefficient of each light receiving element 202 in the storage unit 313.

  When the value of the update counter exceeds a predetermined threshold, time has elapsed since the previous correction coefficient update, and the characteristics of the light receiving element 202 and the like may have changed over time. Therefore, by updating the correction coefficient, it is possible to reduce not only the original variation in characteristics between the light receiving elements 202 but also the influence of fluctuations in the characteristics of the light receiving elements 202 due to aging.

  At this time, the update counter may be reset or may not be reset.

  Thereafter, the process proceeds to step S160.

  On the other hand, if it is determined in step S158 that the update counter does not exceed the predetermined threshold value, the process of step S159 is skipped, the correction coefficient is not updated, and the process proceeds to step S160.

  In step S156, when the light reception difference value of at least one light receiving element 202 exceeds the threshold value, the correction coefficient setting unit 312 determines that the difference between the current and previous normalized light reception values exceeds a predetermined range. Determination is made, and the process proceeds to step S160. This is a case where the distribution of normalized light reception values of each light receiving element 202 this time is not similar to the distribution of normalized light reception values of each light reception element 202 of the previous time.

  In step S160, the correction coefficient setting unit 312 sets the value of the correction coefficient update lock flag to 1. Thereby, the update of the correction coefficient is prohibited.

  In step S161, the correction coefficient setting unit 312 sets the current normalized light reception value as the next comparison normalized light reception value. That is, the correction coefficient setting unit 312 stores the current normalized light reception value of each light receiving element 202 in the storage unit 313 as the previous normalized light reception value. Thereby, when the process of step S155 is executed next, the distribution of the normalized received light value this time is used for comparison with the distribution of the newly detected normalized received light value.

  Thereafter, the correction coefficient update process ends.

  On the other hand, when it is determined in step S152 that there is a direction in which the intensity of the reflected light is less than the predetermined threshold value, or in step S153, it is determined that the difference between the detected distances in each direction exceeds the predetermined range. In this case, the correction coefficient update process is finished as it is. That is, when there is no object that reflects the measurement light at substantially the same distance over all the detection areas, the normalized light reception value is not calculated and the correction coefficient is not updated.

  If it is determined in step S151 that the value of the correction coefficient update lock flag is 1, that is, if update of the correction coefficient is prohibited, the process proceeds to step S162.

  In step S162, the correction coefficient setting unit 312 determines whether the intensity of reflected light in all directions is less than a predetermined threshold. The correction coefficient setting unit 312 determines that the intensity of reflected light in all directions is less than the predetermined threshold when the light reception peak values of all the light receiving elements 202 are less than the predetermined threshold, and the process proceeds to step S163. .

  Note that the threshold used in this process is set to a value equal to or less than the threshold used in the process of step S152, for example. Therefore, when it is determined in step S162 that the intensity of reflected light in all directions is less than the predetermined threshold, it can be considered that no object is detected in all detection regions.

  In step S163, the correction coefficient setting unit 312 sets the value of the correction coefficient update lock flag to 0. Thereby, the update of the correction coefficient is permitted.

  Thereafter, the correction coefficient update process ends.

  On the other hand, in step S162, the correction coefficient setting unit 312 determines that there is a direction in which the intensity of the reflected light is equal to or greater than the predetermined threshold when the light reception peak value of at least one light receiving element 202 is equal to or greater than the predetermined threshold. This is a state in which there is a possibility that an already detected object is continuously detected. Then, the process of step S163 is skipped, and the correction coefficient update process ends while the correction coefficient update flag is set to 1 (update of the correction coefficient is prohibited).

  Accordingly, after the value of the correction coefficient update lock flag is set to 1 in step S160, the update counter is incremented until it is determined in step S162 that the intensity of reflected light in all directions is less than the predetermined threshold. And updating of the correction coefficient is prohibited. That is, when the object for which the normalized light reception value is to be calculated appears in front of the host vehicle and the normalized light reception value is calculated, and the determination condition in step S156 is satisfied, the update counter is only once for the object. Is incremented. Further, when the update counter exceeds a predetermined threshold, the correction coefficient is updated. Thereafter, the increment of the update counter and the update of the correction coefficient are prohibited until the object disappears from the front of the host vehicle. As a result, the update counter is incremented many times for the same object, and the correction coefficient is prevented from being updated.

  Next, a second embodiment of the correction coefficient update process will be described with reference to the flowchart in FIG.

  In steps S171 to S174, processing similar to that in steps S151 to S154 in FIG. 11 is executed.

  In step S175, the correction coefficient setting unit 312 determines whether the variation in the normalized light reception value of each light receiving element 202 is within a predetermined range. For example, when the difference between the minimum value and the maximum value of the normalized light reception value of each light receiving element 202 is equal to or smaller than a predetermined threshold, the correction coefficient setting unit 312 has a variation in the normalized light reception value of each light receiving element 202 within a predetermined range. Is determined to be within. Alternatively, for example, when the difference between the light reception peak values of the adjacent light receiving elements 202 is within a predetermined threshold, the correction coefficient setting unit 312 determines that the variation of the normalized light reception value of each light receiving element 202 is within a predetermined range. judge. If it is determined that the variation in the normalized light reception value of each light receiving element 202 is within the predetermined range, the process proceeds to step S176.

  As described above, it is assumed that the distribution in the horizontal direction of the light reception peak value with respect to the surface having uniform reflection characteristics is substantially smooth. Therefore, in step S175, the object for which the variation of the normalized light reception value of each light receiving element 202 is determined to be within the predetermined range can be regarded as having a surface with substantially uniform reflection characteristics.

  It should be noted that other statistical methods can be used for the determination processing in step S175. For example, the determination can be made using the variance of the normalized received light value.

  In step S176, the update counter is incremented in the same manner as in step S157 of FIG.

  In step S177, the storage unit 313 stores the normalized light reception value of each light receiving element 202.

  In step S178, it is determined whether or not the update counter exceeds a predetermined threshold, as in the process of step S158 in FIG. If it is determined that the update counter exceeds the predetermined threshold, the process proceeds to step S179.

  In step S179, the correction coefficient setting unit 312 updates the correction coefficient. Specifically, the correction coefficient setting unit 312 reads out the normalized received light value stored from the storage unit 313 every time it is determined that the variation of the normalized received light value of each light receiving element 202 is within a predetermined range, The average value of these normalized light reception values is calculated for each light receiving element 202. Then, the correction coefficient setting unit 312 sets the calculated average light reception value of each light receiving element 202 as a new correction coefficient for each light receiving element 202.

  Here, as described above, an object that satisfies the determination condition of step S175 can be regarded as having a surface with uniform reflection characteristics, but in reality, it is not uniform at all. Variations occur in the intensity of reflected light (hereinafter referred to as incident light) incident on the light receiving element 202. The variation in the intensity of the incident light occurs almost randomly for each object. On the other hand, the variation in the normalized light reception value of each light receiving element 202 is caused by the variation in characteristics between the light receiving elements 202 in addition to the variation in the intensity of the incident light. The variation in characteristics between the light receiving elements 202 occurs in substantially the same manner regardless of the difference in objects.

  Therefore, by calculating the average value of the normalized light receiving values of each light receiving element 202, the variation in the intensity of incident light on each light receiving element 202 that occurs almost randomly is offset, and the characteristic variation between the light receiving elements 202 is reduced. Can be extracted. As a result, by setting the average value of the normalized light receiving values of the light receiving elements 202 as the correction coefficient, it is possible to more appropriately correct the characteristic variation between the light receiving elements 202.

  Thereafter, the process proceeds to step S180.

  On the other hand, if it is determined in step S178 that the update counter does not exceed the predetermined threshold, the process in step S179 is skipped, and the process proceeds to step S180 without updating the correction coefficient.

  If it is determined in step S175 that the variation in the normalized light reception value of each light receiving element 202 exceeds the predetermined range, the processes in steps S176 to S179 are skipped, and the process proceeds to step S180.

  In step S180, similarly to the process of step S160 of FIG. 11, the value of the correction coefficient update lock flag is set to 1, and the correction coefficient update process ends.

  On the other hand, if it is determined in step S171 that the value of the correction coefficient update lock flag is 1, the process proceeds to step S181.

  In steps S181 and S182, processing similar to that in steps S162 and S163 in FIG. 11 is executed, and the correction coefficient update processing ends.

  Returning to FIG. 10, in S107, the correction unit 314 corrects the received light value using the correction coefficient. Specifically, the correction unit 314 reads the correction coefficient of each light receiving element 202 from the storage unit 313. For example, when the normalized light reception value of each light receiving element 202 or the average value of the normalized light reception values is used as the correction coefficient, the correction unit 314 divides the light reception peak value of each light receiving element 202 by the correction coefficient. Thus, the light receiving peak value of each light receiving element 202 is corrected. The correction unit 314 supplies information indicating the detection distance of each detection region and the corrected light reception peak value (hereinafter referred to as a corrected light reception peak value) to the object detection unit 315.

  In step S108, the object detection unit 315 detects an object. Specifically, the object detection unit 315 determines the presence or absence of other objects such as other vehicles, pedestrians, road accessories, and the like in the monitoring area based on the detection distance and the corrected light reception peak value of each detection area. Detection of type, direction, distance, etc.

  Note that any method can be adopted as the object detection method of the object detection unit 315.

  Here, an example of the object detection method will be described with reference to FIG.

  The graph of FIG. 13 shows the horizontal distribution of the received light value at the sampling time near the reflected light from the vehicle 351 when the vehicle 351 is traveling in front of the host vehicle. That is, this graph is a graph in which the light reception values of the respective light receiving elements 202 at the sampling time are arranged in the horizontal axis direction in the horizontal arrangement order of the respective light receiving elements 202.

  The measurement light is reflected by the vehicle 351 and received by the light receiving element 202, but there is a time difference from light projection to light reception. Since this time difference is proportional to the distance between the laser radar device 11 and the vehicle 351, the reflected light from the vehicle 351 is measured as a light reception value at a sampling timing (sampling time tn) that matches the time difference. Accordingly, among the light reception values of the respective light receiving elements 202 in the detection region including the vehicle 351, the light reception value particularly at the sampling time tn is increased.

  Further, when the vehicle 351 is present in the front, the reflected light reflected by the vehicle 351 is received by the light receiving element 202, so that the light receiving value of each light receiving element 202 including the vehicle 351 in the detection region becomes large. In particular, since the reflectance of the left and right reflectors 352L and 352R behind the vehicle 351 is high, the light reception value of each light receiving element 202 including the reflectors 352L and 352R in the detection region is particularly large.

  Therefore, as shown in the graph of FIG. 13, two prominent peaks P11 and P12 appear in the distribution of received light values in the horizontal direction. In addition, since the reflected light reflected by the vehicle body between the reflectors 352L and 352R is also detected, the light reception value between the peak P11 and the peak P12 is higher than that in other regions. Thus, it is possible to detect the vehicle ahead by detecting two prominent peaks in the horizontal distribution of the received light values at the same sampling time.

  As described above, by correcting the light reception peak value using the correction coefficient, the positions of the peaks P11 and P12 can be detected more accurately.

  In step S109, the calculation unit 25 supplies the detection result. Specifically, the object detection unit 315 supplies the object detection result to the control unit 21 and the notification unit 302. For example, the notification unit 302 periodically supplies the detection result of the object to the vehicle control device 12 regardless of the presence or absence of the object. Or the notification part 302 supplies the detection result of an object to the vehicle control apparatus 12, only when there exists a danger that a vehicle will collide with the object ahead, for example.

  Thereafter, the process returns to step S102, and the processes of steps S102 to S109 are repeatedly executed.

  In this way, the correction coefficient of each light receiving element 202 is automatically adjusted to an appropriate value according to the individual difference of each component while the host vehicle is traveling. Moreover, the detection accuracy of the object of the laser radar apparatus 11 can be improved by correcting the light reception value using the correction coefficient adjusted appropriately. For example, the object feature detection accuracy and the object tracking accuracy are improved.

<2. Second Embodiment>
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the correction coefficient is updated using an image sensor.

{Configuration example of laser radar device 401}
FIG. 14 shows a configuration example of a laser radar apparatus 401 which is a second embodiment of the laser radar apparatus to which the present invention is applied. In the figure, the same reference numerals are given to the portions corresponding to those in FIG. 1, and the description of the portions having the same processing will be omitted as appropriate because the description thereof is redundant.

  The laser radar device 401 is different from the laser radar device 11 of FIG. 1 in that a calculation unit 411 is provided instead of the calculation unit 25.

  The calculation unit 411 detects an object in the monitoring area based on the measurement result of the light reception value supplied from the measurement unit 24 and the front image obtained by photographing the front of the host vehicle supplied from the image sensor 402, The detection result is supplied to the control unit 21 and the vehicle control device 12.

  Note that the image sensor 402 is installed at a predetermined position of the host vehicle so that the entire monitoring area can be captured, for example.

{Configuration example of calculation unit 411}
FIG. 15 shows a configuration example of the function of the calculation unit 411. In the figure, the same reference numerals are given to the portions corresponding to those in FIG. 7, and the description of the portions having the same processing will be omitted as appropriate because the description thereof is redundant.

  The calculation unit 411 is different from the calculation unit 25 of FIG. 7 in that a detection unit 451 is provided instead of the detection unit 301. The detection unit 451 is different from the detection unit 301 in that a luminance distribution determination unit 461 is added.

  The luminance distribution determination unit 461 detects the luminance distribution of the object ahead of the host vehicle based on the front image supplied from the image sensor 402. Then, the luminance distribution determination unit 461 determines whether or not the luminance distribution of the front object is substantially smooth, and supplies the determination result to the correction coefficient setting unit 312.

{Processing of laser radar device 401}
Next, processing of the laser radar device 401 will be described.

  The correction coefficient adjustment process performed by the laser radar device 401 is the same as the correction coefficient adjustment process performed by the laser radar device 11 described above with reference to FIG.

  The monitoring process by the laser radar device 401 is executed according to the flowchart of FIG. However, the monitoring processing by the laser radar device 401 differs from the monitoring processing by the laser radar device 11 in the correction coefficient update processing in step S106.

  Here, the details of the correction coefficient update processing executed by the laser radar device 401 will be described with reference to the flowchart of FIG.

  In step S201, as in the process of step S6 in FIG. 8, it is determined whether the intensity of reflected light in all directions is equal to or greater than a predetermined threshold, and the intensity of reflected light in all directions is equal to or greater than a predetermined threshold. If determined to be, the process proceeds to step S202.

  In step S202, as in the process of step S7 in FIG. 8, it is determined whether or not the difference in the detection distance in each direction is within a predetermined range, and the difference in the detection distance in each direction is in the predetermined range. If it is determined, the process proceeds to step S203.

  In step S203, the luminance distribution determination unit 461 determines whether the luminance distribution of the object ahead is smooth. Specifically, the luminance distribution determination unit 461 detects the luminance distribution of the portion irradiated with the measurement light in the front image supplied from the image sensor 402. If the detected luminance distribution satisfies the predetermined condition, the luminance distribution determining unit 461 determines that the luminance distribution of the object ahead is smooth, and the process proceeds to step S204.

  It should be noted that any method can be employed for the luminance smoothness determination. For example, the luminance distribution determination unit 461 has a difference between the detected minimum value and maximum value of the luminance that is equal to or smaller than a predetermined threshold value, and the maximum value of the differential value in the differential image of the portion irradiated with the measurement light of the front image. When it is below the predetermined threshold, it is determined that the luminance distribution is smooth.

  In step S204, the received light value is normalized in the same manner as in step S8 of FIG.

  In step S205, the correction coefficient is updated in the same manner as in step S159 in FIG. 11, and the correction coefficient update process ends.

  On the other hand, when it is determined in step S201 that there is a direction in which the intensity of the reflected light is less than the predetermined threshold value, or in step S202, it is determined that the difference between the detection distances in each direction exceeds the predetermined range. If, or in step S203, it is determined that the luminance distribution of the front object is not smooth, the correction coefficient update process is terminated without updating the correction coefficient.

  As described above, in the second embodiment, the front image is used to determine whether or not the luminance distribution of the front object is smooth and the correction coefficient is updated. Therefore, the second embodiment is compared with the first embodiment. Thus, the correction coefficient can be adjusted more quickly and appropriately.

<3. Modification>
Hereinafter, modifications of the above-described embodiment of the present invention will be described.

  The configurations of the laser radar device 11 and the laser radar device 401 are not limited to the examples described above, and can be changed as necessary.

  For example, it is possible to integrate the control unit 21 and the calculation unit 25 or to change the sharing of functions.

  Further, for example, the number of light receiving elements 202, TIA 261, PGA 262, and ADC 263 can be increased or decreased as necessary.

  Further, for example, one or more multiplexers (MUX) that receive a plurality of light reception signals and output a light reception signal selected from the input light reception signals may be provided between the light receiving element 202 and the TIA 261. . In this case, a combination of the TIA 261, the PGA 262, and the ADC 263 may be provided by the number of MUXs, and each group may perform processing such as sampling on a light reception signal output from each MUX.

  In this case, light reception signals from two or more light receiving elements 202 are input to one ADC 263 via one MUX, and each circuit between the two or more light receiving elements 202 and the ADC 263 is connected. Some overlap. Also in this case, the correction coefficient of each light receiving element 202 can be obtained by the same method as in the case where the MUX is not provided.

  In the above description, the example in which the determination process is performed by converting the peak time of each light receiving element 202 into the detection distance in step S7 in FIG. 8 and the like has been described, but the peak time is used as it is for the determination process. Also good. For example, instead of determining whether or not the difference between the detection distances in each direction is within a predetermined range, it is determined whether or not the time difference between the peak times of the respective light receiving elements 202 is within a predetermined range. Also good.

  Further, for example, in the process of step S159 of FIG. 11, the average value of the normalized light reception values of each light receiving element 202 is set as a new correction coefficient of each light receiving element 202, as in the process of step S179 of FIG. You may do it.

  Further, the correction coefficient may be calculated by a calculation different from the above-described calculation using the light reception peak value and the normalized light reception value of each light receiving element 202. For example, the normalized light reception value or the reciprocal of the average value of the normalized light reception values may be used as the correction coefficient.

  Furthermore, in the above, an example in which the present invention is applied to a laser radar device that monitors the front of a vehicle has been shown. However, the present invention is a laser radar that monitors a direction other than the front (for example, side, rear, etc.). The present invention can also be applied to an apparatus.

  The present invention can also be applied to a radar apparatus that uses measurement light other than a laser (for example, measurement light using millimeter waves).

[Computer configuration example]
The series of processes described above can be executed by hardware or can be executed by software. When a series of processing is executed by software, a program constituting the software is installed in the computer. Here, the computer includes, for example, a general-purpose personal computer capable of executing various functions by installing various programs by installing a computer incorporated in dedicated hardware.

  FIG. 17 is a block diagram showing an example of the hardware configuration of a computer that executes the above-described series of processing by a program.

  In a computer, a CPU (Central Processing Unit) 601, a ROM (Read Only Memory) 602, and a RAM (Random Access Memory) 603 are connected to each other by a bus 604.

  An input / output interface 605 is further connected to the bus 604. An input unit 606, an output unit 607, a storage unit 608, a communication unit 609, and a drive 610 are connected to the input / output interface 605.

  The input unit 606 includes a keyboard, a mouse, a microphone, and the like. The output unit 607 includes a display, a speaker, and the like. The storage unit 608 includes a hard disk, a nonvolatile memory, and the like. The communication unit 609 includes a network interface or the like. The drive 610 drives a removable medium 611 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory.

  In the computer configured as described above, the CPU 601 loads the program stored in the storage unit 608 to the RAM 603 via the input / output interface 605 and the bus 604 and executes the program, for example. Is performed.

  The program executed by the computer (CPU 601) can be provided by being recorded on a removable medium 611 as a package medium, for example. The program can be provided via a wired or wireless transmission medium such as a local area network, the Internet, or digital satellite broadcasting.

  In the computer, the program can be installed in the storage unit 608 via the input / output interface 605 by attaching the removable medium 611 to the drive 610. Further, the program can be received by the communication unit 609 via a wired or wireless transmission medium and installed in the storage unit 608. In addition, the program can be installed in the ROM 602 or the storage unit 608 in advance.

  The program executed by the computer may be a program that is processed in time series in the order described in this specification, or in parallel or at a necessary timing such as when a call is made. It may be a program for processing.

  The embodiments of the present technology are not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present technology.

DESCRIPTION OF SYMBOLS 11 Laser radar apparatus 21 Control part 22 Measuring light projection part 23 Light receiving part 24 Measuring part 25 Calculation part 102 Light emitting element 202-1 thru | or 202-16 Light receiving element 253 Sampling part 263-1 thru | or 263-4 A / D converter 301 Detection Unit 311 peak detection unit 312 correction coefficient setting unit 314 correction unit 315 object detection unit 401 laser radar device 402 image sensor 411 calculation unit 451 detection unit 461 luminance distribution determination unit

Claims (6)

A light projecting unit that intermittently projects measurement light that is pulsed laser light;
A plurality of light receiving elements for receiving the reflected light of the measurement light reflected by the object;
A measurement unit that measures a light reception value of each light receiving element by performing sampling of a light reception signal from each light receiving element at a plurality of sampling times;
A correction coefficient setting unit for setting a correction coefficient for correcting the light reception value of each light receiving element;
A correction unit that corrects the received light value of each of the light receiving elements using the correction coefficient;
An object detector that measures a distance from the object based on the received light value after correction, and
The correction coefficient setting unit is configured such that the object has a first condition in which a time difference between sampling times at which a light reception value of each light receiving element reaches a peak is within a first predetermined range, and a surface having uniform reflection characteristics. A laser radar device that sets the correction coefficient when a second condition that can be considered is satisfied. 2. The laser radar device according to claim 1, wherein the second condition is that a variation in a peak value of a light receiving value of each of the light receiving elements is within a second predetermined range. When the first condition and the second condition are satisfied, the storage unit further stores a peak value of a light reception value of each of the light receiving elements,
The second condition is that when the difference between the peak value of the light reception value stored last time and the peak value of the current light reception value is calculated for each light receiving element, the difference falls within a third predetermined range. Item 2. The laser radar device according to Item 1. When the first condition and the second condition are satisfied, the storage unit further stores a peak value of a light reception value of each of the light receiving elements,
The correction coefficient setting unit uses the plurality of received light values stored for each of the light receiving elements when the number of times that the first condition and the second condition are satisfied is a predetermined number of times or more. The laser radar device according to any one of claims 1 to 3. A luminance distribution determination unit that determines whether or not the luminance distribution of the object that reflects the measurement light is smooth based on an image acquired by an image sensor that captures the projection direction of the measurement light;
The laser radar device according to claim 1, wherein the second condition is that the luminance distribution determination unit determines that the luminance of the object is smooth. The correction coefficient setting unit sets the correction coefficient based on a normalized light reception value obtained by normalizing each light reception peak value by a maximum value of the light reception peak values of all the light receiving elements. A laser radar device according to claim 1.

Images