JP6210906B2 - Laser radar equipment - Google Patents

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.

  In the laser radar apparatus, signal delay occurs due to various factors. In addition, a plurality of factors overlap to increase the delay amount. This signal delay causes a decrease in detection accuracy of the laser radar device.

  Conventionally, a method for preventing a decrease in detection accuracy due to the delay of the signal has been proposed. For example, in order to reduce the influence of the delay of the sample pulse used for sampling the received light value with respect to the reflected light of the laser light, it has been proposed to delay the timing of projecting the laser light by a time corresponding to the delay time of the sample pulse. (For example, refer to Patent Document 1).

JP-A-6-230128

  The present invention makes it possible to realize a laser radar device with higher detection accuracy.

A laser radar device according to a first aspect of the present invention includes a light projecting unit that projects measurement light that is pulsed laser light, and a plurality of light beams that receive reflected light of the measurement light from different directions in the horizontal direction. A light receiving element, a plurality of AD converters provided for each of the light receiving elements, for sampling a light receiving signal from each of the light receiving elements, and a peak for detecting a peak of a light receiving value of each of the light receiving elements sampled by the AD converter A detection unit and a time at which the light reception value of each light receiving element peaks or a distance corresponding to the time are generated in a circuit until a light reception signal output from each light receiving element is input to the AD converter. correction unit and, each of said light receiving element after correction for correcting, based on the correction amount set for each of the light receiving element based on the time direction of the displacement of the peak of the light receiving values On the basis of the peak of the received-light value, and a object detecting unit for detecting the object.

In the first aspect of the present invention, measurement light, which is pulsed laser light, is projected, reflected light of measurement light from different directions in the horizontal direction is received, and light reception signals from each light receiving element are sampled. Is detected, and the peak of the light reception value of each sampled light receiving element is detected, and the time when the light reception value of each light receiving element reaches a peak, or the distance corresponding to the time is the light reception signal output from each light receiving element. Is corrected based on the correction amount set for each light receiving element based on the shift in the time direction of the peak of the received light value generated in the circuit until the signal is input to the AD converter . An object is detected based on the peak of the received light value.

Therefore, a laser radar device with higher detection accuracy can be realized. In addition, it is possible to correct the shift in the time direction of the peak of the light reception value due to the delay of the light reception signal, waveform distortion, or the like.

  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. The peak detection unit, the correction unit, and the object detection unit are configured by arithmetic devices such as a microcomputer and various processors, for example.

A laser radar device according to a second aspect of the present invention includes a light projecting unit that projects measurement light that is pulsed laser light, and a plurality of light beams that receive reflected light of the measurement light from different horizontal directions. A light-receiving element; a multiplexer that outputs the light-receiving signal selected from light-receiving signals from the light-receiving elements; an AD converter that samples the light-receiving signal output from the multiplexer; A peak detection unit that detects a peak of the light reception value of the light receiving element, and a time at which the light reception value of each of the light receiving elements reaches a peak, or a light reception signal that is output from each of the light receiving elements is a distance corresponding to the time. setting for each of the light receiving element based but in the time direction of deviation of the peak of the light receiving values occurring in the circuit to be input to the AD converter Comprising a correction unit that corrects, based on the correction amount being based on the peak of the received-light value of each of said light receiving element after correction, and the object detecting unit for detecting the object.

In the second aspect of the present invention, measurement light that is pulsed laser light is projected, reflected light of measurement light from different horizontal directions is received, and the received light from each light receiving element is received. The received light signal selected from is output, the output light reception signal is sampled, the peak of the light reception value of the sampled light reception element is detected, and the time at which the light reception value of each light reception element peaks or at the time A correction in which the corresponding distance is set for each light receiving element on the basis of the shift in the time direction of the peak of the light receiving value generated in the circuit until the light receiving signal output from each light receiving element is input to the AD converter . The object is detected based on the corrected peak of the light receiving value of each light receiving element after correction.

Therefore, a laser radar device with higher detection accuracy can be realized. In addition, it is possible to correct the shift in the time direction of the peak of the light reception value due to the delay of the light reception signal, waveform distortion, or the like.

  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. The peak detection unit, the correction unit, and the object detection unit are configured by arithmetic devices such as a microcomputer and various processors, for example.

  According to the first aspect or the second aspect of the present invention, a laser radar device with higher detection accuracy can be realized.

It is a block diagram which shows one Embodiment of the laser radar apparatus to which this 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 block diagram which shows the structural example of a measurement part. It is a block diagram which shows the structural example of the function of a calculating part. It is a flowchart for demonstrating an object detection process. It is a timing chart for explaining object detection processing. It is a figure for demonstrating the integration process of a light reception value. It is a figure which shows typically the 1st example of the light reception signal input into two ADCs. It is a figure which shows typically the 2nd example of the light reception signal input into two ADCs. It is a figure for demonstrating the example of the detection method of a vehicle. 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. Embodiment 2. FIG. Modified example

<1. Embodiment>
{Configuration example of laser radar device 11}
FIG. 1 shows a configuration example of a laser radar device 11 which is an embodiment of a laser radar device 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 from the light receiving unit 24 based on the analog light reception signal supplied from the light receiving unit 23, and supplies the digital light reception signal indicating the measured light reception value to the calculation unit 25. To do.

  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.

{Configuration example of measurement unit 24}
FIG. 4 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. 5 shows a functional configuration example of the calculation unit 25. The calculation unit 25 is configured to include an integration unit 301, a detection unit 302, and a notification unit 303. The detection unit 302 is configured to include a peak detection unit 311, a correction unit 312, and an object detection unit 313.

  The integrating unit 301 integrates the received light values of the same light receiving element 202 at each sampling time, and supplies the integrated value (hereinafter referred to as an integrated received light value) to the peak detecting unit 311.

  As will be described later, the peak detector 311 detects the peak of the integrated 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 unit 312.

  The correction unit 312 corrects the detection result of the peak of the integrated light reception value of each light receiving element 202 in the time direction, and supplies the detection result after correction to the object detection unit 313.

  The object detection unit 313 detects an object in the monitoring region based on the horizontal and time direction (distance direction) distribution of the integrated light reception value (reflected light intensity) and the detection result of the peak, and controls the detection result. To the unit 21 and the notification unit 303.

  The notification unit 303 supplies the detection result of the object in the monitoring area to the vehicle control device 12.

{Object detection processing}
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 step S <b> 1, 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 onto the entire monitoring region via the light projecting optical system 103.

  In step S2, 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 region in the corresponding direction among the reflected light with respect to the measurement light projected in the process of step S1 via the light receiving optical system 201. 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 S3, 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 light reception signal after A / D conversion to the integration unit 301.

  The details of the sampling process of the received light signal will be described later with reference to FIG.

  In step S4, the integration unit 301 integrates the light reception values up to the previous time and the current light reception values. Thereby, as will be described later with reference to FIG. 8, the received light values at the same sampling time of the received light signals from the same light receiving element 202 are integrated. Further, the integration unit 301 executes the integration process of the received light values in parallel for the received light signals output from the respective ADCs 264. Thereby, the integration of the received light values of the respective light receiving elements 202 is performed individually in parallel.

  In step S5, the control unit 21 determines whether or not the measurement of the received light value has been performed a predetermined number of times (for example, 100 times). If it is determined that the received light value has not been measured a predetermined number of times, the process returns to step S1.

  Thereafter, the processes in steps S1 to S5 are repeatedly executed until it is determined in step S5 that the received light value has been measured a predetermined number of times. Thus, the process of projecting the measurement light and measuring the light reception value of each light receiving element 202 is repeated a predetermined number of times within a measurement period of a predetermined length described later. Further, the measured light reception values are integrated.

  On the other hand, if it is determined in step S5 that the light reception value has been measured a predetermined number of times, the process proceeds to step S6.

  Here, with reference to FIG. 7 and FIG. 8, a specific example of the processing of steps S1 to S5 will be described.

  FIG. 7 is a timing chart showing a specific example of the sampling process of the received light signal, and the horizontal axis of each figure in the figure shows time.

  The uppermost stage in FIG. 7 shows the emission timing of the measurement light. The detection periods TD1, TD2,... Are the minimum unit of the period for performing the object detection process, and the object detection process is performed once in one detection period. Each detection period includes a measurement period TM and a pause period TB.

  The second row in FIG. 7 is an enlarged view of the measurement period TM of the detection period TD1. As shown in this figure, the measurement light is projected a predetermined number of times (for example, 100 times) at a predetermined interval within the measurement period TM.

  The third row in FIG. 7 shows the waveform of the trigger signal that defines the sampling timing of the ADC 263, and the fourth row shows the sampling timing of the received light signal in the ADC 263. The vertical axis in the fourth row 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 was projected. 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, each time the measurement light is projected, 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 received light signal indicating the sampling value (received light value) at each sampling time to the integrating unit 301 with reference to the trigger signal (the time when the trigger signal is input is 0).

  In this way, each time the measurement light is projected, the light reception signal of each light receiving element 202 is sampled. Thereby, the intensity of the reflected light in the detection region of each light receiving element 202 is detected in a predetermined distance unit.

  On the other hand, the suspension period TB is set between the measurement period TM and the measurement period TM of the next detection period, and the projection of the measurement light and the measurement of the received light value are suspended. Then, for example, the object detection process based on the measurement result of the light reception value in the immediately preceding measurement period TM, the inspection of the light receiving unit 23 and the measurement unit 24, and the like are executed during the suspension period TB.

  Next, a specific example of the light reception value integration process will be described with reference to FIG. FIG. 8 shows an example of integration processing for 100 received light signals output from a certain light receiving element 202 when measuring light is projected 100 times during a measurement period of one cycle. The horizontal axis in FIG. 8 indicates the time (sampling time) with the trigger signal input timing as a reference (time 0), and the vertical axis indicates the received light value (sampling value).

  As shown in this figure, for each measurement light from the first time to the 100th time, the received light signal is sampled at sampling times t1 to ty, and the received light values at the same sampling time are integrated. For example, the received light values at the sampling time t1 for each measurement light from the first time to the 100th time are integrated. In this manner, the received light values at the same sampling time of the received light signals from the same light receiving element 202 sampled within the detection period are integrated. This integrated value is used for subsequent processing.

  By performing this integration processing, even when the S / N ratio of the received light signal with respect to one measurement light is low, the signal component is amplified, and random noise is averaged and reduced. As a result, the signal component and the noise component can be easily separated from the received signal, and the light receiving sensitivity can be substantially increased. Thereby, for example, the detection accuracy of a distant object or an object with low reflectivity is improved.

  Returning to FIG. 6, in step S <b> 6, the peak detector 311 detects the peak of the received light value. Specifically, the integration unit 301 supplies the peak detection unit 311 with the calculation result of the integrated light reception value within one detection period.

  The peak detector 311 detects the horizontal and temporal peaks of the integrated light reception value with respect to the reflected light. More specifically, the peak detection unit 311 detects a sampling time at which the integrated light reception value peaks for each light receiving element 202. That is, the peak detector 311 detects the peak in the time direction of the integrated light reception value for each horizontal detection region corresponding to each light receiving element 202. Thereby, the position where the intensity of reflected light peaks in the distance direction from the host vehicle is detected for each detection region in the horizontal direction. That is, the distance from the host vehicle at a position where there is a high possibility that an object that reflects the measurement light exists in each detection region is detected.

  At this time, the light receiving element 202 (detection region) where the integrated light reception value peaks at each sampling time may be further detected. That is, you may make it detect the peak of the horizontal direction of the integrated light reception value in each sampling time. Thereby, in the distance direction from the host vehicle, a horizontal position (detection region) where the intensity of the reflected light peaks at every predetermined interval (for example, about every 25 to 250 mm) is detected.

  Then, the peak detection unit 311 supplies the detection result to the correction unit 312.

  Note that any method can be adopted as the peak detection method of the peak detection unit 311.

  In step S7, the correction unit 312 corrects the detection result of the peak of the received light value. Specifically, the circuit length and frequency characteristics between each light receiving element 202 and the ADC 263 corresponding to each light receiving element 202 are different for each light receiving element 202. Accordingly, a difference occurs between the light receiving elements 202 in the time until the light receiving signal output from each light receiving element 202 is input to each ADC 263. In addition, a difference occurs between the light receiving elements 202 in the waveform distortion that occurs until the light receiving signal output from each light receiving element 202 is input to each ADC 263. Accordingly, even when reflected light having the same waveform is incident on each light receiving element 202 at the same time, there may be a time lag or a waveform difference in the received light signal input to each ADC 263.

  For example, FIG. 9 and FIG. 10 schematically illustrate the waveform of the light reception signal input to each ADC 263 connected to each light receiving element 202 when the reflected light having the same waveform is incident on two different light receiving elements 202 at the same time. It shows.

  For example, when the circuit length between the light receiving element 202 and the ADC 263 is different, as shown in FIG. 9, a time direction shift occurs due to the difference in the delay amount of the circuit between the light receiving signal 1 and the light receiving signal 2. . As a result, a deviation d1 occurs between the sampling times of the peak P1 of the received light signal 1 and the peak P2 of the received light signal 2.

  Further, for example, when the frequency characteristics of the circuit between the light receiving element 202 and the ADC 263 are different, as shown in FIG. 10, a difference occurs in the waveform due to a difference in waveform distortion generated in the light receiving signal 3 and the light receiving signal 4. . As a result, a deviation d2 occurs between the sampling times of the peak P3 of the light reception signal 3 and the peak P4 of the light reception signal 4.

  Due to the deviation of the peak in the time direction, a difference occurs in the detection result of the distance to the same object by the light receiving element 202 (light reception signal). For example, when the sampling time at which the light reception value reaches a peak is shifted by one, if the sampling frequency is 600 MHz, a difference in distance of 250 mm occurs, and if the sampling frequency is 6 GHz, a difference in distance of 25 mm occurs.

  Therefore, the correction unit 312 corrects the sampling time at which the integrated light reception value of each light receiving element 202 detected in the process of step S <b> 6 becomes a peak using a predetermined correction amount set for each light receiving element 202. This correction amount is obtained for each light receiving element 202 by the following method, for example, at the development stage before the laser radar device 11 is sold.

  First, the light emitting element 102 and each light receiving element 202 are optically connected by an optical fiber having a predetermined length that is not included in the configuration of the laser radar apparatus 11, and the operation of the laser radar apparatus 11 is performed in this state. Is called. Then, the measurement light emitted from the light emitting element 102 is irradiated to each light receiving element 202 through the optical fiber. Then, the peak detector 311 detects a sampling time at which the light reception value of each light receiving element 202 reaches a peak, based on the light reception signal output from each light receiving element 202. Here, since the length of the optical fiber corresponds to the optical path length of the measurement light and its reflected light, the light receiving value of each light receiving element 202 is ideally a distance that is ½ of the length of the optical fiber. At a sampling time corresponding to (hereinafter referred to as ideal sampling time). The amount of deviation between this ideal sampling time and the sampling time at which the light receiving value of each light receiving element 202 actually peaks (hereinafter referred to as the actual sampling time) is set as the correction amount for each light receiving element 202.

  A plurality of optical fiber lengths are used to obtain a plurality of deviation amounts between the ideal sampling time and the actual measurement sampling time for each light receiving element 202, and an average value of the deviation amount is used as a correction amount for each light receiving element 202. You may make it set.

  Further, the method for obtaining the correction amount described above is an example, and other methods may be used. Furthermore, for example, the correction amount may be obtained by calculation based on the length of the circuit between each light receiving element 202 and the ADC 263, frequency characteristics, and the like.

  By the processing in step S7, the shift in the time direction of the peak of the received light value generated in the circuit between each light receiving element 202 and each ADC 263 is corrected. As a result, the difference in the shift amount in the time direction of the peak of the received light value between the light receiving elements 202 is also eliminated.

  Note that the correction amount in the distance direction may be obtained instead of the correction amount in the time direction, and the distance corresponding to the sampling time at which the light reception value of each light receiving element 202 reaches a peak may be corrected.

  In step S8, the object detection unit 313 detects an object. Specifically, the object detection unit 313 detects other vehicles in the monitoring region based on the horizontal and temporal distributions of the integrated light reception values (that is, the intensity of the reflected light) and the peak detection results within the detection period. The presence / absence of an object such as a pedestrian or an obstacle, and the type, direction, and distance of the object are detected. Here, the detection result of the peak of the integrated light reception value after being corrected in the process of step S7 is used.

  Note that any method can be adopted as the object detection method of the object detection unit 313.

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

  The graph of FIG. 11 shows the horizontal distribution of the integrated light reception values at the sampling time near the return of 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 integrated 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 integrated light reception values of the respective light receiving elements 202 in the detection region including the vehicle 351, the integrated light reception value particularly at the sampling time tn becomes large.

  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 integrated light reception 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 integrated 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. 11, two prominent peaks P11 and P12 appear in the distribution of the accumulated light reception values in the horizontal direction. Moreover, since the reflected light reflected by the vehicle body between the reflectors 352L and 352R is also detected, the integrated 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 integrated light reception values at the same sampling time.

  In step S9, the calculating part 25 supplies a detection result. Specifically, the object detection unit 313 supplies the object detection result to the control unit 21 and the notification unit 303. For example, the notification unit 303 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 303 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 S1, and the processes of steps S1 to S9 are repeatedly executed. That is, the process of detecting an object based on the integrated light reception value is repeated for each detection period.

  As described above, by correcting the detection result of the peak of the light reception value of each light receiving element 202, the object detection accuracy of the laser radar device 11 can be improved.

<2. Modification>
Hereinafter, modifications of the above-described embodiment of the present invention will be described.

  The configuration of the laser radar device 11 is not limited to the example shown in FIG. 1 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.

  For example, the number of light receiving elements 202, TIA 261, PGA 262, and ADC 263 can be increased or decreased as necessary. For example, it is possible to increase the number of light receiving elements 202 to expand the monitoring area, or to subdivide the detection area in the monitoring area. Conversely, it is possible to reduce the number of light receiving elements 202 to narrow the monitoring area or to aggregate the detection areas in the monitoring area.

  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 and some become different. In this case as well, the correction amount in the time direction of the peak of the received light value can be obtained by the same method as in the case where the MUX is not provided.

  In addition, for example, the present invention can also be applied to the case where the received light value obtained by sampling is subjected to interpolation processing to detect the peak of the received light value. In this case, for example, it is possible to obtain the correction amount in the time direction or perform the correction in the time direction by the same method as described above using the detection result of the peak of the received light value after interpolation. . In this case, correction of the peak of the received light value in the time direction can be performed in units of time shorter than the sampling interval.

  Furthermore, the present invention can also be applied to, for example, a laser radar apparatus that performs object detection processing without performing integration of received light values.

  Further, the present invention can also be applied to a laser radar device used for other purposes than for vehicles.

[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. 12 is a block diagram illustrating a hardware configuration example 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 12 Vehicle control apparatus 21 Control part 22 Measuring light projection part 23 Light receiving part 24 Measuring part 25 Calculation part 101 Drive circuit 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 Integration unit 302 Detection unit 311 Peak detection unit 312 Correction unit 313 Object detection unit

Claims (2)

A light projecting unit for projecting measurement light that is pulsed laser light;
A plurality of light receiving elements for receiving reflected light of the measurement light from different directions in the horizontal direction;
A plurality of AD converters that are provided for each of the light receiving elements and perform sampling of a light reception signal from each of the light receiving elements;
A peak detector for detecting a peak of a light receiving value of each of the light receiving elements sampled by the AD converter;
The light reception value generated in the circuit until the light reception signal output from each light receiving element is input to the AD converter at the time when the light reception value of each light receiving element peaks or the distance corresponding to the time A correction unit that corrects based on a correction amount set for each of the light receiving elements based on a shift in the time direction of the peak of
A laser radar device comprising: an object detection unit configured to detect an object based on a peak of the light reception value of each light receiving element after correction. A light projecting unit for projecting measurement light that is pulsed laser light;
A plurality of light receiving elements for receiving reflected light of the measurement light from different directions in the horizontal direction;
A multiplexer that outputs the received light signal selected from the received light signals from the light receiving elements;
An AD converter that samples the light reception signal output from the multiplexer;
A peak detector for detecting a peak of a light receiving value of the light receiving element sampled by the AD converter;
The light reception value generated in the circuit until the light reception signal output from each light receiving element is input to the AD converter at the time when the light reception value of each light receiving element peaks or the distance corresponding to the time A correction unit that corrects based on a correction amount set for each of the light receiving elements based on a shift in the time direction of the peak of
A laser radar device comprising: an object detection unit configured to detect an object based on a peak of the light reception value of each light receiving element after correction.

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