JP2019078602A - Laser ranger - Google Patents

Abstract

To measure an object which is small and is more distant.SOLUTION: The laser ranger according to an embodiment includes: a light source for outputting a plurality of pulse lights at predetermined intervals; a processing unit for increasing the intensity of a signal component in a reflection pulse train, which is a pulse train formed of pulse lights output at the predetermined intervals reflected by an object, using signals based on the predetermined time intervals; and a measurement unit for measuring the distance to the object reflecting the pulse train, on the basis of the reflection pulse train with the intensity of the signal component increased.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser distance measuring device.

  Conventionally, there is known a technique of emitting a laser beam to an object and measuring the distance to the object based on the reflected light reflected by the object. A laser distance measuring device to which such a technology is applied is also called LiDAR (Light Detection and Ranging), and is applied to various fields. The object is a measurement object present around the laser distance measuring device, and includes all objects that are irradiated with the laser light emitted from the light source and reflect the laser light to the laser distance measuring device.

Patent No. 5500617 specification

  Here, in the above-described laser distance measuring apparatus, when it is intended to measure an object at a longer distance, the peak output of pulse light emission of the light source is increased in order to obtain a higher S / N ratio (signal noise ratio). It is conceivable. However, in order to increase the peak output of pulse light emission of the light source, the circuit scale becomes large, and the laser distance measuring device itself becomes large. For example, in order to drive a near-infrared pulse laser diode of several W or more, a large circuit for switching a power supply voltage of several tens of V or more, high voltage, and large current at high speed is required. Becomes larger.

  The present invention is made in view of the above, and an object of the present invention is to provide a small laser distance measuring apparatus capable of measuring an object of a longer distance.

  In order to solve the problems described above and achieve the object, a laser distance measuring device according to an aspect of the present invention includes a light source that outputs a plurality of pulse lights at predetermined time intervals, and a signal based on the predetermined time intervals. A processing unit that increases the intensity of a signal component in a reflected pulse train in which a plurality of pulse light beams output at predetermined time intervals are reflected by an object, and a reflection in which the intensity of the signal component is increased And a measurement unit configured to measure a distance to an object reflected from the pulse train based on the pulse train.

  According to one aspect of the present invention, it is possible to measure a small, longer distance object.

FIG. 1 is a block diagram showing an example of the configuration of the laser distance measuring device according to the first embodiment. FIG. 2 is a diagram for explaining an example of light emission timing according to the first embodiment. FIG. 3 is a diagram for explaining an example of addition processing by the addition processing unit according to the first embodiment. FIG. 4 is a diagram showing an example of the interpolation signal according to the first embodiment. FIG. 5A is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the first embodiment. FIG. 5B is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the first embodiment. FIG. 5C is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the first embodiment. FIG. 6 is a flowchart showing the procedure of processing by the laser distance measuring device according to the first embodiment. FIG. 7 is a block diagram showing an example of the configuration of the laser distance measuring device according to the second embodiment. FIG. 8 is a diagram showing the input and output of the matched filter processing unit according to the second embodiment. FIG. 9 is a diagram for explaining an example of matched filter processing by the matched filter processing unit according to the second embodiment. FIG. 10 is a diagram showing an example of the matched filter by the matched filter processing unit according to the second embodiment. FIG. 11A is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the second embodiment; FIG. 11B is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the second embodiment. FIG. 11C is a diagram for describing an example of processing by the mixed circuit diagnosis / separation processing unit according to the second embodiment. FIG. 12 is a flowchart showing the procedure of processing by the laser distance measuring device according to the second embodiment.

  Hereinafter, the laser distance measuring device according to the embodiment will be described with reference to the drawings. In addition, the relationship of the dimension of each element in drawing, the ratio of each element, etc. may differ from reality. Even between the drawings, there may be a case where the dimensional relationships and ratios differ from one another.

First Embodiment
FIG. 1 is a block diagram showing an example of the configuration of the laser distance measuring device 100 according to the first embodiment. As shown in FIG. 1, the laser distance measuring device 100 includes a light source 110, a light source drive circuit 120, a photodetector 130, an analog front end 140, an AD (Analog-to-digital) converter 150, and a control circuit 160. , Communication I / F 170. Here, the laser distance measuring apparatus 100 can appropriately be provided with an optical system such as a collimator lens and a condenser lens, a rotation mechanism such as a motor, and the like in addition to the illustrated configuration.

  For example, the laser distance measuring device 100 can be provided with a collimating lens that emits output light (laser light) emitted by the light source 110 as parallel laser light. In such a case, the collimator lens is disposed such that the light incident surface faces the light emitting surface of the light source 110, and converts the laser light output from the light source 110 into parallel light and emits the parallel light.

  In addition, for example, the laser distance measuring device 100 is a condensing lens that causes the laser light (or the laser light emitted from the collimating lens) output from the light source 110 to condense the reflected light reflected by the object on the photodetector 130. It can be equipped. In such a case, the condenser lens is disposed such that the light emission surface faces the detection surface of the photodetector 130, and condenses the light reflected from the outside on the photodetector 130. For example, the condensing lens is a plano-convex lens, a Fresnel lens, or the like.

  Further, for example, the laser distance measuring apparatus 100 performs two-dimensional distance measurement by two-dimensional distance measurement by performing two-dimensional distance measurement by performing two-dimensional distance measurement by performing two-dimensional distance measurement. In order to realize three-dimensional LiDAR, a micro electro mechanical systems (MEMS) mirror for changing the emission direction of the laser light, a motor for rotating a structure for scanning the laser light, or the like can be provided. For example, the MEMS mirror is swung up and down, and scans the laser light in the vertical direction by reflecting the laser light emitted from the light source. In addition, the motor scans the laser beam further in the horizontal direction by rotating the structure itself for scanning the laser beam in the vertical direction about the vertical direction. The laser distance measuring device 100 can realize two-dimensional LiDAR and three-dimensional LiDAR by further including these configurations.

  The light source 110 is a light emitting element such as a laser diode (LD), and outputs output light (for example, laser light) according to a drive signal from the light source drive circuit 120. Here, based on the drive signal from the light source drive circuit 120, the light source 110 outputs pulsed light in which laser light is output with a predetermined pulse width. The light source 110 also outputs a plurality of pulse lights at predetermined time intervals. The details of these will be described later. In addition, when the laser distance measuring device 100 includes a collimating lens, the light source 110 outputs pulsed light to the collimating lens.

  The light source drive circuit 120 outputs a drive signal according to the control signal from the control circuit 160 to the light source 110, thereby causing the light source 110 to output a laser beam (pulsed light).

  The photodetector 130 detects reflected light from the outside. Specifically, the photodetector 130 detects pulsed light output from the light source 110 and reflected by an object. For example, the photo detector 130 may be a photomultiplier tube (PMT), a photoconductive element such as CdS or PbS using a change in electrical resistance due to light irradiation, or a photovoltaic photodiode (pNj junction) Photo Diode (PD) etc. The photodiode is, for example, a PN photodiode, a PIN photodiode, an avalanche photodiode or the like. In addition, when the laser distance measuring device 100 includes a condensing lens, the photodetector 130 detects the reflected light condensed by the condensing lens.

  The analog front end 140 amplifies the reflected light detected by the photodetector 130. For example, the analog front end 140 has a transimpedance amplifier and an amplification circuit. The transimpedance amplifier converts the current generated by the photodetector 130 based on the reflected light into a voltage (electric signal), and outputs the voltage (electric signal) to the amplification circuit. The amplification circuit amplifies the electric signal input from the transimpedance amplifier to a level capable of signal analysis, and outputs the amplified signal to the AD converter 150.

  The AD converter 150 converts the electrical signal input from the analog front end 140 into a digital signal. Specifically, the AD converter 150 performs sampling processing on the input electrical signal at a predetermined sampling rate to generate a digital signal obtained by converting the electrical signal into discrete numerical values. Then, the AD converter 150 stores the digital signal in the data buffer 163 in the control circuit 160.

  As shown in FIG. 1, the control circuit 160 includes a control unit 161, an encoded light emission timing generation unit 162, a data buffer 163, an addition processing unit 164, a distance calculation unit 165, and a mixed line diagnosis / separation processing unit 166. And various controls in the laser distance measuring apparatus 100 are executed. For example, the control circuit 160 controls the output of pulsed light by the light source 110. In addition, the control circuit 160 measures the distance to the object from which the pulse light is reflected by executing various processes on the received reflected light. Here, the control circuit 160 makes it possible to execute the measurement of the distance to an object which is compact and located in a longer distance by the processing of each part described above. The details of the processing of each part will be described later.

  A communication I / F (interface) 170 controls communication of data output to an external device. For example, the communication I / F 170 is realized by a network card, a network adapter, an NIC (Network Interface Controller) or the like, and outputs the result of distance measurement to an external device.

  The outline of the laser distance measuring device 100 has been described above. As described above, the laser distance measuring apparatus 100 enables processing of the control circuit 160 to measure the distance to an object that is compact and located in a longer distance. Specifically, the control circuit 160 outputs a plurality of pulse lights at a predetermined time interval, and uses the signal based on the predetermined time interval to increase the intensity of the signal component of the reflected light to generate S of the reflected light. By improving the / N ratio, it is possible to measure the distance to an object located in a longer distance without increasing the circuit size. The details of the process in control circuit 160 will be described below.

  A control unit 161 in the control circuit 160 controls the entire laser distance measuring device 100. For example, the control unit 161 controls the generation of the light emission timing by the coded light emission timing generation unit 162. Also, for example, the control unit 161 controls sampling processing by the AD converter 150. Also, for example, the control unit 161 controls the addition processing by the addition processing unit 164. The control unit 161 also controls the distance calculation by the distance calculation unit 165. Also, for example, the control unit 161 controls the processing by the mixed line diagnosis / separation processing unit 166.

  Under the control of the control unit 161, the encoded light emission timing generation unit 162 generates a light emission timing at which the light source 110 emits pulsed light, and outputs the generated light emission timing to the light source drive circuit 120. The light source drive circuit 120 causes the light source 110 to output pulsed light by outputting a drive signal at the light emission timing input from the encoded light emission timing generation unit 162. That is, the light source 110 emits pulsed light at the light emission timing generated by the coded light emission timing generation unit 162.

  Here, the encoded light emission timing generation unit 162 generates a light emission timing such that the light source 110 outputs a plurality of pulse lights at a predetermined time interval. Specifically, when the encoded light emission timing generation unit 162 superimposes a plurality of pulse lights shifted by a predetermined time interval on a plurality of pulse lights, the time when the number of pulse lights overlapping at the same time is smaller The light emission timing is generated so that a plurality of pulse lights are output at intervals.

FIG. 2 is a diagram for explaining an example of light emission timing according to the first embodiment. Here, in FIG. 2, the light emission timing is indicated by “1” when light is emitted and “0” when light is not emitted. For example, as shown in FIG. 2, the encoded light emission timing generation unit 162 generates light emission timing for outputting pulse light of pulse width “τ _P ” four times in a predetermined time “τ”. Here, the coded light emission timing generation unit 162 sets the time between each pulsed light to a predetermined time interval. For example, as shown in FIG. 2, the encoded light emission timing generation unit 162 generates the light emission timing of the first pulse light (“1” at the left end in the drawing) and the second pulse light (2 in the drawing from the left). Set “4τ _P ” as a time interval between the light emission timing of the 1st “1”). That is, the encoded light emission timing generation unit 162 sets the light emission timing for emitting the second pulse light at a time four times the time of the pulse width “τ _P ” after emitting the first pulse light. Generate

  Similarly, the encoded light emission timing generation unit 162 determines a time interval between the light emission timing of the second pulse light and the light emission timing of the third pulse light (the third “1” from the left in the drawing), The time intervals between the emission timing of the third pulse light and the emission timing of the fourth pulse light (“1” at the right end in the drawing) are set. Here, the coded light emission timing generation unit 162 is configured to calculate a time interval between the first pulse light and the second pulse light, a time interval between the second pulse light and the third pulse light, and a third pulse. Each time interval is set such that the time intervals between the light and the fourth pulse light are different from each other.

For example, as illustrated in FIG. 2, the encoded light emission timing generation unit 162 sets “6τ _P ” as a time interval between the second pulse light and the third pulse light. Further, as shown in FIG. 2, the encoded light emission timing generation unit 162 sets “8τ _P ” as a time interval between the third pulse light and the fourth pulse light. This is to set such that, when each pulsed light is shifted on the time axis by a time interval, the number of pulsed lights overlapping each pulsed light before shifting is one. For example, when each pulse light emitted at the light emission timing shown in FIG. 2 is shifted to the left by “4τ _P ”, the first pulse light before the shift and the second pulse light after the shift are generated. Will overlap. Furthermore, each pulse light to "4.tau _P" component of the time is shifted to the left, when shifted to the time left "6Tau _P" component, of each pulse light after the shift, only the third pulse light It will overlap with the second pulse light before shift (and the first pulse light not shifted).

  As described above, when the encoded light emission timing generation unit 162 superimposes a plurality of pulse lights shifted by a predetermined time interval on a plurality of pulse lights, a time interval in which the number of pulse lights overlapping at the same time decreases. The light emission timing is generated so that a plurality of pulse lights are output. Here, the encoded light emission timing generation unit 162 generates, for example, a binary encoded signal “1000100000100000001” illustrated in FIG. 2 as light emission timing, and outputs the generated signal to the light source drive circuit 120. The light source drive circuit 120 causes the light source 110 to emit pulsed light by outputting a drive signal at the timing "1" of the input encoded signal "1000100000100000001". In the following, a plurality of pulse lights at the time “τ” generated at the light emission timing generated by the encoded light emission timing generation unit 162 will be referred to as a pulse train.

Note that the light emission timing shown in FIG. 2 is merely an example, and the light emission timing generated by the encoded light emission timing generation unit 162 is not limited to the example shown in FIG. For example, the number of pulse lights to be output within the range of time “τ”, the time of pulse width “τ _P ” with respect to time “τ”, and the like can be set arbitrarily. Further, the time “τ” of the pulse train can be set arbitrarily as long as it is a time range between the measurement of the distance to one object and the measurement of the distance to the next object.

  Further, in the light emission timing shown in FIG. 2, when each pulse light is shifted by a time interval on the time axis, the case has been described where the number of pulse lights overlapping each pulse light before the shift is one. The form is not limited to this. For example, the overlap of the pulsed light may be set to "10%" or less. In this setting, when each pulse light included in the pulse train is shifted by the time interval, the ratio of the number of times the other pulse lights overlap with the total number of the pulse train before shift and the pulse train after shift is set. Ru. For example, when "100" pulse lights are included in a pulse train, "100" pulse trains of "99" pulse trains which are respectively shifted in the time interval between the unshifted pulse train and each pulse are arranged. . In the “100” pulse trains, the number of times each pulse light overlaps with other pulse lights is set to “10” or less. Note that the light emission timing may be a case where a unique one is assigned to each of the laser distance measurement devices, but a random number may be assigned to each measurement process and may be determined based on the random number.

  The laser distance measuring device 100 according to the present application can increase the intensity of the signal component in the reflected light and improve the S / N ratio by using the above-described pulse train for measuring the distance to the object. The details of the processing for reflected light will be described below.

  When the light source 110 outputs a plurality of pulse lights at the light emission timing generated by the above-described encoded light emission timing generation unit 162, the plurality of pulse lights are reflected by an external object and detected by the photodetector 130. For example, the photodetector 130 detects a plurality of pulse lights in which a plurality of pulse lights output at the light emission timing shown in FIG. 2 are reflected by an object. In the following, a plurality of pulse lights in which a plurality of pulse lights are reflected by an object will be referred to as a reflection pulse train.

  The reflected pulse train detected by the photodetector 130 is amplified by the analog front end 140, converted into a digital signal by the AD converter 150, and stored in the data buffer 163. The data buffer 163 stores the digital signal input from the AD converter 150.

  The addition processing unit 164 generates a pulse train signal in which the time of pulse light in the reflection pulse train is shifted by a predetermined time interval, and adds the generated pulse train signal to the reflection pulse train to increase the intensity of the signal component in the reflection pulse train. Let Specifically, the addition processing unit 164 generates pulse train signals in which the reflected pulse train is shifted by the time interval between each pulse. Then, the addition processing unit 164 adds the generated pulse train signal to the reflected pulse train to increase the strength of the signal component in the reflected pulse train. The addition processing unit 164 is also described as a processing unit.

  FIG. 3 is a diagram for explaining an example of addition processing by the addition processing unit 164 according to the first embodiment. Here, in FIG. 3, (1) shows a reflection pulse train, and (2) to (4) show pulse train signals generated from the reflection pulse train. Further, FIG. 3 shows a reflected pulse train and a pulse train signal in which the waveform of pulse light is indicated by a straight triangular wave, but in practice the reflected pulse train and the pulse train signal processed by the addition processing unit 164 are AD It is a digital signal converted by the converter 150. That is, the reflected pulse train and the pulse train signal processed by the addition processing unit 164 are discrete numerical values sampled from the reflected pulse train by the AD converter 150.

  For example, the addition processing unit 164 reads the reflected pulse train (1) shown in FIG. 3 stored by the data buffer 163, and reads the reflected pulse train (1) between the first pulse light and the second pulse light. The pulse train signal (2) shifted by the time interval of is generated. The addition processing unit 164 also generates a pulse train signal (3) obtained by shifting the pulse train signal (2) by the time interval between the second pulse light and the third pulse light. The addition processing unit 164 also generates a pulse train signal (4) obtained by shifting the pulse train signal (3) by the time interval between the third pulse light and the fourth pulse light.

  Then, the addition processing unit 164 adds the generated pulse train signals (2) to (4) to the reflected pulse train (1) to obtain the lower portion “(1) + (2) + (3) in FIG. The addition signal shown in “+ (4)” is generated. That is, the addition processing unit 164 generates an addition signal in which the intensity of the signal component of the reflected pulse train is increased. Then, the addition processing unit 164 outputs the addition signal to the distance calculation unit 165.

  Thus, the addition processing unit 164 can improve the S / N ratio of the reflected pulse train by the above-described addition processing. Hereinafter, improvement of the S / N ratio by the addition process will be described. For example, as shown in FIG. 3, the waveform (voltage waveform) of the pulsed light included in the reflected pulse train is set to “f (t)”. Then, the maximum value when f (t) is shifted and added for the time interval between each pulse light is represented by the following equation (1), assuming that “the number of pulses N = 4”.

  Here, as shown in FIG. 3, by setting the light emission timing so that two or more pulse lights do not overlap between the reflected pulse train and each pulse train signal, the white noise voltage “n” is set to f (t). Assuming that (V / HzHz) is added, the S / N ratio (SNR) is expressed by the following equation (2). In addition, "B" in Formula (2) shows the bandwidth of a light receiving circuit (photo detector 130).

  As shown in the equation (2), the SN ratio is doubled by using a pulse train of four pulse lights as compared with the case of a single pulse light. In general, the S / N ratio is improved by “√N” times with N pulse lights.

  As described above, in the laser distance measuring device 100 according to the first embodiment, the S / N ratio of the reflected light reflected by the object is obtained by using a pulse train that is a plurality of pulse lights output at predetermined time intervals. Can be improved, and the distance to an object located at a longer distance can be accurately measured without increasing the circuit size.

  Here, in the embodiment described above, the case where the addition processing is performed using the digital signal converted by the AD converter 150 has been described. However, the embodiment is not limited to this, and may be, for example, a case of using an interpolation signal obtained by interpolating values between sample points of discrete digital signals. FIG. 4 is a diagram showing an example of the interpolation signal according to the first embodiment. For example, the addition processing unit 164 reads the digital signal shown in the upper part of FIG. 4 from the data buffer 163, and executes spline interpolation or Lagrange interpolation on the read digital signal. Thereby, the addition processing unit 164 generates an interpolation signal obtained by interpolating values between sample points of the digital signal, as shown in the lower part of FIG. Then, the addition processing unit 164 performs the above-described addition processing using the generated interpolation signal.

  Referring back to FIG. 1, the distance calculation unit 165 measures the distance to an object that has reflected a plurality of pulse lights based on the addition signal on which the addition processing has been performed by the addition processing unit 164. For example, the distance calculation unit 165 measures the distance to an object that has reflected a plurality of pulse lights by performing distance measurement of a TOF (Time of Flight) method. In such a case, the distance calculation unit 165 calculates the distance from the delay time of the signal based on the plurality of pulse lights and the addition signal. For example, the distance calculation unit 165 determines an object based on the time difference between the output start time of the plurality of pulse signals and the time when the peak is maximum in the added signal (the appearance timing of the maximum peak in FIG. 3) Measure the distance to The distance calculation unit 165 is also described as a measurement unit.

  In the case of realizing two-dimensional LiDAR or three-dimensional LiDAR, the laser distance measuring device 100 outputs a plurality of pulse lights (pulse trains) in each direction for scanning, and the reflected light from each direction (reflection Each pulse train is detected.

  As described above, the laser distance measuring apparatus 100 according to the first embodiment improves the S / N ratio of the reflected light by using a pulse train which is pulse light output at predetermined time intervals, but the laser distance The measuring apparatus 100 can determine not only the improvement of the S / N ratio described above, but also whether the light detected by the photodetector 130 is reflected light. Specifically, the mixed line diagnosis / separation processing unit 166 determines, using a signal based on a predetermined time interval, whether the light received from the outside is a reflected pulse train or not. The mixed line diagnosis / separation processing unit 166 is also described as a determination processing unit.

  In recent years, laser distance measuring devices have been used in various fields and are becoming familiar. Therefore, another LiDAR different from the own device may be used in the surroundings. In such a case, when the own device detects pulsed light output by another LiDAR, an erroneous measurement result will be presented. Therefore, the laser distance measuring apparatus 100 can separate light from other LiDARs by using a pulse train.

  For example, it is assumed that there is another LiDAR near the own apparatus, and each LiDAR emits light with a pulse train encoded at different timings. In this case, the following three patterns can be considered for the reflected light or the direct light of the light emitted from the other LiDAR that is incident on the device itself. For example, as three patterns, (1) when the signal is large and the pulse train can be identified sufficiently, (2) the signal is small, but when the pulse train has no correlation with the pulse train of its own device, (3) the signal is small, There is a case where the pulse train has a partial correlation with the pulse train of its own device.

  For example, in the case of (1), the mixed line diagnosis / separation processing unit 166 determines whether or not the light detected by the photodetector 130 is a reflected pulse train by identifying the pulse train. That is, the mixed line diagnosis / separation processing unit 166 is a reflection pulse train based on whether or not the time interval between the pulse lights in the detected pulse train is the time interval generated by the coded light emission timing generation unit 162. It is determined whether or not.

  Also, for example, in the case of (2), since the pulse train has no correlation with its own device, even if the above-described addition processing is performed, the strength of the signal component in the other LiDAR pulse trains is not increased. Other LiDAR pulse trains can be separated (excluded) without performing.

  Next, in the case of (3), since the pulse train has a partial correlation with the pulse train of its own device, when the above-described addition processing is performed, the strength of the signal component in the other LiDAR pulse trains is increased. . Therefore, in the case of (3), the mixed line diagnosis / separation processing unit 166 according to the first embodiment generates a light reception signal in which the time of a plurality of light received over time is shifted by a predetermined time interval. Based on whether or not the signal value when the generated light reception signal is added to the plurality of light signals is a value corresponding to the addition, it is determined whether or not the plurality of lights are reflected pulse trains. That is, the cross-track diagnosis / separation processing unit 166 generates the addition signal by executing the same processing as the addition processing described above, and determines the reflected pulse train based on the generated addition signal.

  5A to 5C are diagrams for explaining an example of processing performed by the mixed circuit diagnosis / separation processing unit 166 according to the first embodiment. Here, in FIG. 5A to FIG. 5C, the pulse train that emitted pulse light at the light emission timing shown in FIG. 2 is the reflected pulse train reflected by the object, and the pulses (other machine pulses in FIG. 5) An example of processing in the case of being included is shown. 5A to 5C, (1) shows a plurality of pulse lights (reflected pulse trains including other machine pulses) detected by the photodetector 130, and (2) to (4) are generated from the reflected pulse trains. 7 shows a pulse train signal. Moreover, in FIG. 5A-FIG. 5C, the addition signal which added the pulse-train signal with respect to the reflected pulse train is shown in the lower stage. In addition, below, the pulse output from the own apparatus is described also as an own machine pulse.

  For example, as shown in FIG. 5A, when the above-described addition processing is performed on the reflected light in which the other-machine pulse is included between the third own-machine pulse and the fourth own-machine pulse in the reflected pulse train, As shown in FIG. 5A, the addition signal “(1) + (2) + (3) + (4)” obtained by adding 1) to (4) is a signal based on the other machine pulse besides the own machine pulse. Will be included. For example, as shown in FIG. 5A, the addition signal includes a peak due to the other machine pulse alone, and a peak added after the timing of the other machine pulse and the own machine pulse overlap after the shift. The mixed line diagnosis / separation processing unit 166 discriminates the reflected pulse train by the following processing in order to prevent such a peak from being erroneously processed as the signal of the own machine at the detectable intensity.

  Specifically, the mixed line diagnosis / separation processing unit 166 carries out processing in which the pulse train signal is thinned out when executing the above-described addition processing, and determines a reflected pulse train based on a change in the addition signal resulting from this processing. For example, as shown in FIG. 5B, the mixed line diagnosis / separation processing unit 166 generates the pulse train signal of (3) in FIG. 5A when generating the pulse train signal from the reflected pulse train (1) including other machine pulses. Instead, only the pulse train signals of (2) and (4) are generated to perform addition processing. That is, in the plurality of pulse train signals generated by shifting the time between pulses, the mixed line diagnosis / separation processing unit 166 generates a plurality of pulse train signals excluding any pulse train signal, and executes the addition processing.

  When such addition processing with thinning out is performed, after addition processing, the signal of only the other machine pulse has the same peak intensity as the case without thinning (in the case of FIG. 5A), or the signal itself is lost It will be done. Further, a signal obtained by adding the own-machine pulse to the other-machine pulse has a peak corresponding to the overlap number and the overlap position. On the other hand, the signal to which only the own machine pulse is added has peak intensity approximated each time, regardless of which pulse train signal is thinned out. That is, in the signal in which only the own machine pulse is added, the peak intensity in which the peak intensity (for example, the peak intensity corresponding to one pulse) decreases from the peak intensity when thinning is not performed (in the case of FIG. 5A) It becomes. Therefore, assuming that the number of own-machine pulses is sufficiently large and the number of overlap between own-machine pulses and other-machine pulses is sufficiently small, the number of times the mixed line diagnosis / separation processing unit 166 performs addition processing after thinning (thinning With respect to the number of times of addition processing performed by changing the pulse train signal, the peak intensity is the same when compared with a certain number of trials or more, and the peak intensity is not reduced (when full addition) The peak which is also lowered can be determined as the peak to which only the own-machine pulse is added.

  For example, in addition processing in which the pulse train signals of (2) and (4) are generated except for (3), as shown in FIG. 5B, the strength of the signal to which only the own machine pulse is added is reduced to 3/4. Do. Here, the peak intensity of the other machine pulse alone does not change, and the peak intensity of the signal obtained by adding the other machine pulse and the own machine pulse becomes the peak intensity of the own machine pulse only by thinning. Also, for example, in the addition processing in which the pulse train signals of (3) and (4) are generated except for (2), as shown in FIG. 5C, the strength of the signal to which only the own machine pulse is added is 3/4 To decrease. Here, the peak intensity of the other machine pulse alone does not change, and the peak intensity of the signal obtained by adding the other machine pulse and the own machine pulse becomes the peak intensity of the other machine pulse only by thinning. Moreover, except for (2), in the addition processing in which the pulse train signals of (3) and (4) are generated, there is one that disappears at the peak of the other device pulse.

  As described above, the mixed line diagnosis / separation processing unit 166 executes the addition processing a plurality of times while changing the pulse train signal to be thinned out, and includes the other machine pulse by referring to the peak change after the addition processing. The own machine pulse is determined from the reflected pulse train. That is, in the mixed line diagnosis / separation processing unit 166, the peak intensities after the addition processing are similar to each other in the plurality of addition processing (FIGS. 5B and 5C), and the peak intensities are the peak intensities at the time of total addition. It is determined that the peak which is 3/4 of the peak is a peak to which only the own-machine pulse is added. Then, the mixed line diagnosis / separation processing unit 166 determines that the plurality of pulse lights included in the peak at the time of full addition corresponding to the determined peak are the reflected pulse trains of the own machine.

  As described above, the mixed line diagnosis / separation processing unit 166 determines a reflected pulse train from the plurality of pulse lights detected by the photodetector 130. The addition processing unit 164 performs the above-described addition processing using a plurality of pulse lights determined to be reflected pulse trains by the mixed line diagnosis / separation processing unit 166.

  In the embodiment described above, the process in the case of determination based on the result of thinning out the pulse train signal of (2) and the pulse train signal of (3) has been described as an example, but the embodiment is limited to this. Alternatively, for example, the determination may be made in consideration of the result of the addition process in which the pulse train signal of (4) is thinned out. That is, the number of trials of the decimation addition can be set arbitrarily. For example, the number of trials of decimation addition may be set in accordance with the number of pulse lights included in the pulse train output from the own device.

  Next, the procedure of the mixed line diagnosis and separation process described above will be described. FIG. 6 is a flowchart showing the procedure of processing by the laser distance measuring device 100 according to the first embodiment. As shown in FIG. 6, the mixed line diagnosis / separation processing unit 166 determines whether or not the plurality of pulse lights detected by the photodetector 130 can be detected without addition processing (step S101). Here, if it is determined that the signal can be detected (Yes at step S101), the mixed line diagnosis / separation processing unit 166 determines whether the detected signal (a plurality of pulse lights) has the same timing as the pulse train of the own machine. It determines (step S102).

  Here, if the detected signal has the same timing as the pulse train of the own machine (Yes at step S102), the mixed line diagnosis / separation processing unit 166 determines the detected signal as the pulse train of the own machine (step S103). On the other hand, if the detected signal does not have the same timing as the pulse train of the own machine (No at Step S102), the mixed line diagnosis / separation processing unit 166 determines the detected signal as the pulse train of the other machine (Step S104).

  On the other hand, if it is determined in step S101 that the signal is not a detectable signal (No in step S101), the crossroads diagnosis / separation processing unit 166 performs addition processing (step S105). Is determined (step S106). Here, if the signal is not a detectable signal (No at Step S106), the mixed line diagnosis / separation processing unit 166 determines that there is no reflected light (Step S113).

  On the other hand, if it is determined in step S106 that the signal can be detected (YES in step S106), the mixed line diagnosis / separation processing unit 166 determines a thinning out signal (step S107), and executes the addition processing after thinning out (step S107). Step S108). Then, when the mixed line diagnosis / separation processing unit 166 repeats the addition processing after decimation a specified number of times (Yes at step S109), a certain number of times or more is smaller than the value of the addition processing before decimation, and addition after decimation It is determined whether or not approximate values have been output between processing values (step S110).

  Here, when a value which is smaller than the value of the addition process before decimation and is similar between the values of the addition process after decimation is output a certain number of times or more (Yes at step S110), the mixed line diagnosis / separation processing unit The step S 166 determines the corresponding signal as the own pulse train (step S 111). On the other hand, when a certain number of times or more is smaller than the value of the addition process before decimation and no approximate value is output between the values of the addition process after decimation (No at step S110), the mixed line diagnosis / separation processing unit 166 is determined to be a pulse train of another machine (step S112). The mixed line diagnosis / separation processing unit 166 repeatedly executes the processing of steps S107 to S109 until the addition processing after thinning-out is repeated the designated number of times in the above-described processing.

  As described above, according to the first embodiment, the light source 110 outputs a plurality of pulse lights at predetermined time intervals. The addition processing unit 164 uses the signal based on the predetermined time interval to increase the intensity of the signal component in the reflected pulse train in which the pulse train, which is a plurality of pulse lights output at the predetermined time interval, is reflected by the object. The distance calculation unit 165 measures the distance to the object reflecting the pulse train based on the reflected pulse train in which the intensity of the signal component is increased. Therefore, the laser distance measuring apparatus 100 according to the first embodiment can improve the S / N ratio without increasing the circuit size, and can measure a small-sized object over a long distance. Do.

  Further, according to the first embodiment, the addition processing unit 164 generates a pulse train signal in which the time of pulse light in the reflection pulse train is shifted by a predetermined time interval, and adds the generated pulse train signal to the reflection pulse train. , Increase the intensity of the signal component in the reflected pulse train. Therefore, the laser distance measuring device 100 according to the first embodiment makes it possible to easily improve the S / N ratio in the reflected pulse train.

  Further, according to the first embodiment, when the light source 110 superimposes a plurality of pulse lights shifted by a predetermined time interval on a plurality of pulse lights, the number of pulse lights overlapping at the same time is smaller. Output a plurality of pulse lights at time intervals. Therefore, the laser distance measuring device 100 according to the first embodiment makes it possible to improve to a higher S / N ratio.

  Further, according to the first embodiment, the mixed line diagnosis / separation processing unit 166 determines, using a signal based on a predetermined time interval, whether the light received from the outside is a reflected pulse train. Therefore, the laser distance measuring device 100 according to the first embodiment makes it possible to perform accurate distance measurement even if there is another LiDAR around it.

  Further, according to the first embodiment, the mixed line diagnosis / separation processing unit 166 generates a light reception signal obtained by shifting the time of the plurality of light received over time by a predetermined time interval, and generates the generated light reception signal. It is determined whether or not the plurality of lights are reflection pulse trains based on whether or not the signal value in the case of being added to the plurality of light signals is a value corresponding to the addition. Therefore, the laser distance measuring device 100 according to the first embodiment makes it possible to easily separate other LiDAR pulse lights.

  Further, according to the first embodiment, the light source 110 outputs a plurality of pulse lights at different time intervals. Therefore, the laser distance measuring device 100 according to the first embodiment makes it possible to generate a pulse train specific to the own device.

Second Embodiment
Next, a second embodiment will be described. Hereinafter, the same components as those of the first embodiment may be denoted by the same reference numerals and descriptions thereof may be omitted. In the first embodiment described above, the case of performing the addition process for the process of improving the S / N ratio has been described. In the second embodiment, a case will be described in which matched filter processing is performed as processing for improving the S / N ratio.

  FIG. 7 is a block diagram showing an example of the configuration of a laser distance measuring device 100a according to the second embodiment. The laser distance measuring apparatus 100a according to the second embodiment has a point in which the control circuit 160a has a matching filter processing unit 168 instead of the addition processing unit 164 in comparison with the laser distance measuring apparatus 100 according to the first embodiment. , The point having reference waveform data 167, and the processing content by the control unit 161a and the mixed line diagnosis / separation processing unit 166a are different. Hereinafter, this point will be mainly described.

  The reference waveform data 167 is a reference waveform based on the light emission timing generated by the encoded light emission timing generation unit 162. For example, the reference waveform data 167 is a waveform in which a peak appears at the time interval of the light emission timing shown in FIG. The reference waveform data 167 may be generated and stored in advance, or may be stored each time the light emission timing is generated by the encoded light emission timing generation unit 162.

  The control unit 161a according to the second embodiment controls the process performed by the matched filter processing unit 168. Further, the control unit 161a controls the processing by the mixed line diagnosis / separation processing unit 166a.

  The matched filter processing unit 168 increases the intensity of the signal component in the reflected pulse train by executing matched filter processing using a reference waveform in which peaks appear at predetermined time intervals with respect to the reflected pulse train. Specifically, the matched filter processing unit 168 performs matched filter processing on the reflected pulse train using the reference waveform data 167. That is, the matched filter processing unit 168 convolutes and integrates the function of the same waveform as that of the pulse train with respect to the waveform (voltage waveform) “f (t)” of the pulse light included in the reflected pulse train, Perform matched filter processing to obtain N ratio. The matched filter processing unit 168 is also described as a processing unit.

  Here, the impulse response “h (t)” of the matched filter that maximizes the S / N ratio of “f (t)” is given by “h (t) = kf (τ−t)”. Therefore, the output when processed by this filter is shown by the following equation (3).

  That is, as shown in the equation (3), the matched filter processing unit 168 integrates the reference pulse wave with respect to the inputted pulse light wave while temporally shifting the reference wave, thereby maximizing the S / N ratio. obtain. Therefore, the matched filter processing unit 168 executes the process shown in FIG. FIG. 8 is a diagram showing the input and output of the matched filter processing unit 168 according to the second embodiment. For example, the matched filter processing unit 168 executes matched filter processing on the input “f (t)” using “h (t) = kf (τ−t)” as the reference waveform, g (t) is obtained.

  Hereinafter, an example of the process of the matched filter processing unit 168 will be described with reference to FIG. FIG. 9 is a diagram for explaining an example of matched filter processing by the matched filter processing unit 168 according to the second embodiment. Here, in FIG. 9, the integration is performed while temporally shifting the reference waveform “kf (τ−t + λ)” with respect to the waveform (voltage waveform) “f (λ)” of the pulse light included in the reflected pulse train. Output “g (t)” when performing Further, FIG. 9 shows an example where the pulse train is encoded by “1000100000100000001” shown in FIG. 2 and the waveform is shown by a triangular wave. Moreover, in FIG. 9, the case of "k = 3.33" is shown.

  For example, as shown in (1) to (4) of FIG. 9, the matched filter processing unit 168 shifts the reference waveform “kf (τ−t + λ)” in time and integrates at each time position. Then, each peak shown by (1) to (4) in the output "g (t)" is acquired. In the case of time "t" in which the pulses of "f (λ)" and "kf (τ-t + λ)" do not overlap, the output is "g (t) = 0" as shown in (1) of FIG. Become. Further, when a signal for one pulse is convoluted and integrated, the output "g (t)" has a small peak as shown in (2) and (4) of FIG. Then, in the case of “t = τ” in which all the pulses of “f (λ)” and “kf (τ−t + λ)” overlap, as shown in (3) of FIG. 9, the output “g (t)” is Indicates the maximum value. The small peaks of (2) and (4) all take 1/4 of the maximum value. This is because, with respect to the output of four pulse lights, encoding is performed so that two or more pulses do not overlap when other than “t = τ”.

  Hereinafter, the improvement of the S / N ratio by the matched filter processing will be described. As shown in FIG. 9, the time “t” at which the output is maximum is when “t = τ”, and the output is expressed by the following equation (4).

  Here, assuming that the white noise voltage “n (V / √Hz)” is added to the input to the matched filter, the S / N ratio (SNR) is expressed by the following equation (5).

Further, assuming that one pulse width is “τ _P ” and the number of pulses included in the pulse train is “N”, the S / N ratio (SNR) is expressed by the following equation (6).

  That is, the S / N ratio can be improved by increasing the number of pulses as shown in equation (6). Hereinafter, an example of the improvement of the S / N ratio by the matched filter process will be described with reference to FIG. FIG. 10 is a diagram illustrating an example of the matched filter by the matched filter processing unit 168 according to the second embodiment. Here, FIG. 10 shows an example in which noise is added to “f (λ)” shown in FIG. Further, FIG. 10 shows that “f (λ)” of “1” is added with white noise of RMS “0.28” and maximum amplitude “2”. As shown in the upper part of FIG. 10, in the signal before matched filter processing, the signal of “f (λ)” is buried in noise. On the other hand, in the output “g (t)” of the matched filter processing, a large peak appears at “t = τ” ((3) in the figure), and it is understood that the S / N ratio is improved. .

  Referring back to FIG. 7, the mixed line diagnosis / separation processing unit 166 a uses a reference waveform in which peaks appear at predetermined time intervals and a waveform obtained by modifying the reference waveform with respect to a plurality of lights received with time. The matched filter processing is executed, and it is determined whether the plurality of lights are reflected pulse trains based on whether or not the result of the matched filter processing changes before and after the deformation of the reference waveform. The mixed line diagnosis / separation processing unit 166a is also described as a determination processing unit.

  As in the first embodiment, also in the laser distance measuring device 100a according to the second embodiment, it is possible to separate light from other LiDAR by using a pulse train. Here, among the three patterns described in the first embodiment, (1) and (2) in the laser distance measuring device 100a according to the second embodiment are the same as in the first embodiment. Light from other LiDAR can be separated.

  That is, in the case of (1) described above (when the signal is large and the pulse train can be sufficiently identified), the mixed line diagnosis / separation processing unit 166a identifies the pulse train to reflect the light detected by the photodetector 130. It is determined whether or not it is a pulse train. In the case of (2) described above (the signal is small but the pulse train has no correlation with the pulse train of its own device), even if the matched filter processing described above is executed because the pulse train has no correlation with its own device, The intensity of the signal component in the LiDAR pulse train is not increased, and other LiDAR pulse trains can be separated (excluded) without performing special processing.

  Further, in the case of (3) described above, since the pulse train has a partial correlation with the pulse train of its own device, the strength of signal components in other LiDAR pulse trains is increased when the matching process described above is executed. Become. Therefore, the mixed line diagnosis / separation processing unit 166a separates the light from the other LiDARs by matched filter processing involving thinning, as in the case of the addition processing described above.

  Here, for example, when very strong light is incident, the output of the matched filter processing may be large, and it may be determined as a reflection pulse train of the own device. That is, in the case of matched filtering, when a large signal is input, the output becomes large even if only a single pulse is overlapped. Therefore, the mixed line diagnosis / separation processing unit 166a according to the second embodiment determines whether or not the incident pulse light is a reflected pulse train by thinning out the pulses in the reference waveform (modifying the reference waveform).

  11A to 11C are diagrams for explaining an example of processing by the mixed circuit diagnosis / separation processing unit 166a according to the second embodiment. Here, in FIG. 11A to FIG. 11C, the pulse train that has emitted the pulse light at the light emission timing shown in FIG. 2 is between the third own pulse and the fourth own pulse in the reflected pulse string reflected by the object. An example of processing when another device pulse is included is shown. Further, in FIGS. 11A to 11C, (1) to (4) show schematic diagrams of the matched filter processing, and the lower part shows the output “g (t)” of the matched filter processing.

  For example, as shown in FIG. 11A, in the case where the above-mentioned matched filter processing is performed on the reflected light in which other machine pulses are included between the third own machine pulse and the fourth own machine pulse in the reflected pulse train: As shown in FIG. 11A, the output “g (t)” includes a signal based on another machine pulse in addition to the own machine pulse. For example, as shown in FIG. 11A, the output “g (t)” includes a peak generated only by the other-machine pulse, and a peak output when the other-machine pulse and the own-machine pulse overlap. The mixed line diagnosis / separation processing unit 166a determines a reflected pulse train by the following processing in order to prevent such a peak from being erroneously processed as a signal of the own machine at a detectable intensity.

  Specifically, the mixed line diagnosis / separation processing unit 166a performs matched filter processing in which the pulses in the reference waveform are thinned out when performing the matched filter processing described above, and a change in the output "g (t)" due to this processing The reflected pulse train is determined based on For example, as shown in FIG. 11B, the mixed line diagnosis / separation processing unit 166a thins out the third pulse from the reference waveform and executes matched filter processing. That is, the mixed line diagnosis / separation processing unit 166a deforms the reference waveform in the matched filter processing, and executes the matched filter processing using the deformed reference waveform.

  When matching filter processing with such thinning out is performed, the signal when only the other machine pulse in the output “g (t)” in the matched filtering processing overlaps the pulse of the reference waveform is not thinned out (FIG. 11A Or the signal itself is lost. Further, the signal when the other device pulse and the own device pulse simultaneously overlap with the pulse of the reference waveform has a peak corresponding to the overlapping number and the overlapping position. On the other hand, the signal when only the own machine pulse overlaps with the pulse of the reference waveform has a peak intensity approximated each time, regardless of which pulse is thinned out. That is, in the signal in which only the own machine pulse overlaps with the pulse of the reference waveform, the peak intensity (for example, peak intensity corresponding to one pulse) decreases from the peak intensity when thinning is not performed (case of FIG. 11A) Peak intensity. Therefore, assuming that the number of self-machine pulses is sufficiently large and the number of self-machine pulses and other-machine pulses simultaneously overlapping the pulse of the reference waveform is sufficiently small, the mixed line diagnosis / separation processing unit 166 performs matched filtering after thinning. With a certain number of trials or more with respect to the number of times of performing (number of times of matched filtering performed by changing the position of thinning pulse in the reference waveform), the same peak intensity is obtained and the intensity is thinned out A peak that is lower than the peak intensity when there is no peak can be determined as the peak of the own-machine pulse only.

  For example, when the third pulse in the reference waveform is removed, as shown in FIG. 11B, the strength of the signal when only the own pulse overlaps the reference waveform is reduced to 3/4. Here, the peak intensity of the signal when only the other machine pulse overlaps the reference waveform does not change, and the peak intensity of the signal where the other machine pulse and the own machine pulse simultaneously overlap the reference waveform is reduced by thinning. Only the same peak intensity as when overlapping with the reference waveform. Further, for example, when the second pulse in the reference waveform is removed, as shown in FIG. 11C, the strength of the signal when only the own-machine pulse overlaps with the reference waveform decreases to 3⁄4. Here, the peak intensity of the signal when only the other machine pulse overlaps with the reference waveform does not change, and the peak intensity of the signal when the other machine pulse and the own machine pulse simultaneously overlap with the reference waveform peak is reduced by thinning. The same peak intensity as when the other device pulse overlaps with the reference waveform pulse is obtained. In addition, when the second pulse in the reference waveform is removed, there is a case in which only the other device pulse disappears at the peak when the reference waveform is overlapped.

  As described above, the mixed line diagnosis / separation processing unit 166a executes the matching filter processing a plurality of times while changing the pulse to be thinned out in the reference waveform, and refers to the change in the peak after the processing. The own machine pulse is determined from the reflected pulse train including the pulse. That is, in the mixed line diagnosis / separation processing unit 166a, in multiple matched filter processes (FIGS. 11B and 11C), the peak intensities after the process are at the same level and the peak intensities when the thinning is performed without thinning It is determined that the peak which is 3/4 of the peak of the own machine pulse. Then, the mixed line diagnosis / separation processing unit 166a determines that the plurality of pulse lights serving as the output source of the determined peak are the reflected pulse trains of the own machine.

  In the embodiment described above, the process in the case of determination based on the result of matched filter processing in the case of thinning out the third and second pulses in the reference waveform has been described as an example, but the embodiment is limited to this Alternatively, for example, the determination may be made in consideration of the result of the matched filtering process in which the fourth pulse is thinned out. That is, the position of the thinning pulse and the number of trials of matched filtering can be set arbitrarily. For example, the position of the thinning pulse or the number of trials may be set according to the number of pulse lights included in the pulse train output from the own machine.

  Next, the procedure of the mixed line diagnosis and separation process described above will be described. FIG. 12 is a flowchart showing the procedure of processing by the laser distance measuring device 100a according to the second embodiment. As shown in FIG. 12, the mixed line diagnosis / separation processing unit 166a determines whether or not the plurality of pulse lights detected by the photodetector 130 can be detected without matching filter processing (step S201). Here, if it is determined that the signal can be detected (Yes at step S201), the mixed line diagnosis / separation processing unit 166a determines whether the detected signal (a plurality of pulse lights) has the same timing as the pulse train of the own machine. It determines (step S202).

  Here, if the detected signal has the same timing as the pulse train of the own machine (Yes at step S202), the mixed circuit diagnosis / separation processing unit 166a determines the detected signal as the pulse train of the own machine (step S203). On the other hand, if the detected signal does not have the same timing as the pulse train of the own machine (No at Step S202), the mixed line diagnosis / separation processing unit 166a determines the detected signal as the pulse train of the other machine (Step S104).

  On the other hand, if it is determined in step S201 that the signal is not a detectable signal (No in step S201), the mixed line diagnosis / separation processing unit 166a executes matched filter processing (step S205). It is determined (step S206). Here, if the signal is not a detectable signal (No at Step S206), the mixed circuit diagnosis / separation processing unit 166a determines that there is no reflected light (Step S213).

  On the other hand, if it is determined in step S206 that the signal can be detected (Yes in step S206), the mixed line diagnosis / separation processing unit 166a creates a thinning matching filter in which pulses are thinned out (step S207), and after thinning. The matched filter process is executed (step S208). Then, when the mixed line diagnosis / separation processing unit 166a repeats matching filter processing after decimation for the specified number of times (Yes at step S209), the value is smaller than the value of the matching filter processing before decimation more than a certain number of times and after decimation. It is determined whether or not values approximate to the values of matched filter processing have been output (step S210).

  Here, when a value which is smaller than the value of the matched filter processing before decimation by a fixed number of times and which approximates the values of the matched filter processing after decimation is output (Yes at step S210), mixed line diagnosis / separation The processing unit 166a determines the corresponding signal as the pulse train of its own device (step S211). On the other hand, when the value which is smaller than the value of the matched filter processing before decimation more than a fixed number of times and the value approximate to the value of the matched filter processing after decimation is not output (No at step S210) The processing unit 166a determines that it is a pulse train of another device (step S212). The mixed line diagnosis / separation processing unit 166a repeatedly executes the processing of steps S207 to S209 until the matched filter processing after thinning is repeated the designated number of times in the above-described processing.

  As described above, according to the second embodiment, the matched filter processing unit 168 performs matched filter processing using a reference waveform in which peaks appear at predetermined time intervals with respect to the reflected pulse train. The intensity of the signal component in the reflected pulse train is increased. Therefore, the laser distance measuring device 100a according to the second embodiment makes it possible to easily improve the S / N ratio in the reflected pulse train.

  Further, according to the second embodiment, the mixed line diagnosis / separation processing unit 166a modifies the reference waveform in which peaks appear at predetermined time intervals and the reference waveform with respect to a plurality of lights received with time. Matched filter processing using the above-described waveforms is respectively executed, and it is determined whether or not the plurality of lights are reflected pulse trains based on a change in the result of the matched filter processing before and after deformation of the reference waveform. Therefore, the laser distance measuring device 100a according to the second embodiment enables accurate distance measurement even if another LiDAR is present in the periphery.

  In the above-described embodiment, the laser distance measuring apparatus including the addition processing unit 164 and the matched filter processing unit 168 has been described. However, the embodiment is not limited to this. For example, the laser distance measurement apparatus may include both the addition processing unit 164 and the matched filter processing unit 168. In such a case, for example, the processing unit to be used may be switched according to the frequency band of the circuit associated with light reception or the length of one pulse.

  Further, the present invention is not limited by the above embodiment. What is configured by appropriately combining the above-described constituents is also included in the present invention. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the present invention are not limited to the above embodiment, and various modifications are possible.

  100, 100a laser distance measurement device, 110 light source, 120 light source drive circuit, 130 photo detector, 140 analog front end, 150 AD converter, 160 control circuit, 161, 161 a control unit, 162 encoded light emission timing generation unit, 163 data buffer, 164 addition processing unit (processing unit), 165 distance calculation unit (measurement unit), 166, 166a Mixed line diagnosis / separation processing unit (determination processing unit), 167 reference waveform data, 168 matched filter processing unit (processing unit)

Claims (8)

A light source which outputs a plurality of pulse lights at predetermined time intervals;
A processing unit that increases the intensity of a signal component in a reflected pulse train in which pulse trains, which are a plurality of pulse lights output at the predetermined time interval, are reflected by an object using a signal based on the predetermined time interval;
A measurement unit configured to measure a distance to an object reflected by the pulse train based on the reflected pulse train in which the intensity of the signal component is increased;
Laser distance measuring device.   The processing unit generates a pulse train signal in which the time of pulse light in the reflected pulse train is shifted by the predetermined time interval, and the generated pulse train signal is added to the reflected pulse train to increase the intensity of the signal component in the reflected pulse train. The laser distance measuring device according to claim 1, wherein   The processing unit performs matched filter processing using a reference waveform in which a peak appears at the predetermined time interval on the reflected pulse train, thereby increasing the strength of the signal component in the reflected pulse train. The laser distance measuring device as described in.   The light source outputs a plurality of pulse lights at time intervals in which the number of pulse lights overlapping at the same time is smaller when overlapping a plurality of pulse lights shifted by the predetermined time interval with respect to the plurality of pulse lights. The laser distance measuring device according to any one of claims 1 to 3.   The laser according to any one of claims 1 to 4, further comprising a determination processing unit that determines whether light received from the outside is the reflected pulse train using a signal based on the predetermined time interval. Distance measuring device.   The determination processing unit generates a light reception signal obtained by shifting the time of the plurality of lights received temporally by the predetermined time interval, and generates a signal value when the generated light reception signal is added to the plurality of light signals. The laser distance measuring device according to claim 5, wherein it is determined whether or not the plurality of lights are the reflected pulse train based on whether or not the value is a value according to addition.   The determination processing unit executes matched filter processing using a reference waveform in which peaks appear at predetermined time intervals and a waveform obtained by modifying the reference waveform on a plurality of light beams received over time. The laser distance measuring device according to claim 5, wherein it is determined whether or not the plurality of lights are the reflected pulse train based on a change in the result of the matched filter processing before and after the deformation of the reference waveform.   The laser distance measuring device according to any one of claims 1 to 7, wherein the light source outputs a plurality of pulse lights at different time intervals.

Images