Distance measuring device

Abstract

The present invention provides a distance measuring device, wherein a characteristic setting unit (7) uses the temporal change of the amount of received light obtained by the light receiving unit (3) as light receiving information, and extracts at least one of the light receiving amount range of the pulse light other than the irradiated light emitted from the light emitting unit (2) and the light receiving time range as a designated range based on one or more light receiving information. A light receiving integration unit (6) generates accumulated light receiving information by integrating at least a portion of the information obtained based on the light receiving information on a time axis that makes the light emission timing consistent over multiple light emission. A distance calculation unit (8) removes or determines the distance noise generated by the pulse light other than the irradiated light based on the designated range extracted by the characteristic setting unit, and calculates the distance to the object that reflected the irradiated light.

Description

Technical Field

[0001] The present invention relates to a technology for measuring the distance to an object that reflects the light using light. Background Art

[0002] Distance measuring devices are known that irradiate light, receive reflected light from an object, measure the time of flight (hereinafter referred to as TOF) of the light from the time of irradiation to the time of reception, and calculate the distance to the object that reflected the light based on the measured TOF. TOF is an abbreviation of Time Of Flight.

[0003] Patent Document 1 below describes a distance measuring device using a SPAD array comprising a plurality of SPADs as a photodetector. SPAD stands for Single Photon Avalanche Diode, and is a highly sensitive avalanche photodiode operating in Geiger mode.

[0004] In a photodetector using a SPAD array, the number of pulse signals output from each SPAD (hereinafter referred to as the response count) is counted, and the waveform represented by the time series of these count values ​​is detected as the received light waveform. Furthermore, by repeatedly performing measurements and integrating the received light waveform, the effects of interference light entering the SPAD array can be suppressed.

[0005] Patent Document 1: Japanese Patent No. 5644294

[0006] However, as a result of detailed research by the inventors, the following problems were discovered in the conventional technology described in Patent Document 1.

[0007] For example, if a distance measuring device is mounted on a vehicle, there is a possibility that light from a distance measuring device mounted on another vehicle may be mistakenly detected as reflected light from an object. That is, in TOF, the light reception timing is determined based on the pulsed waveform that appears in the received light waveform, so a pulsed waveform appears at the light reception timing of the light from the other distance measuring device. Even if the detection is a single shot, due to the high intensity of the received light, this pulsed waveform differs from normal noise and cannot fully achieve the suppression effect brought about by accumulation, resulting in the possibility of mistakenly identifying it as a reflection from the target. Furthermore, the same problem arises when receiving light from another distance measuring device not mounted on the vehicle, so-called interference light. Summary of the Invention

[0008] One aspect of the present invention is to provide a technique for suppressing erroneous detection caused by pulsed disturbance light.

[0009] One embodiment of the present invention is a distance measuring device including a light emitting unit, a light receiving unit, a characteristic setting unit, a received light integrating unit, and a distance calculating unit.

[0010] The light emitting unit irradiates light toward an object. The light receiving unit receives light reflected from the object. The characteristic setting unit uses temporal variations in the amount of received light obtained by the light receiving unit as light reception information and, based on one or more pieces of light reception information, extracts at least one of a range of light reception amounts and a range of light reception times of pulsed light other than the irradiated light emitted from the light emitting unit as a designated range.

[0011] The light receiving integration unit generates integrated light receiving information by integrating at least a portion of information obtained from the light receiving information on a time axis that aligns the light emission timings over a plurality of light emission events. The distance calculation unit removes or determines distance noise generated by pulsed light other than the irradiation light within the specified range extracted by the characteristic setting unit, and calculates the distance to the object that reflected the irradiation light.

[0012] According to this configuration, the distance to the object is calculated using the accumulated light reception information obtained by accumulating a plurality of light reception information. This makes it possible to suppress the amount of received light having a pulsed waveform caused by pulsed light other than irradiation light in the received light waveform indicated by the accumulated light reception information.

[0013] Furthermore, by using a designated range extracted from a plurality of light-receiving information items to be integrated, distance noise is removed or determined. This makes it possible to suppress false detections due to distance noise, that is, detecting the distance even when no object is present. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a block diagram showing the configuration of a distance measuring device.

[0015] Figure 2 This is an explanatory diagram showing the relationship between light emission timing and received light waveform.

[0016] Figure 3 This is an explanatory diagram showing the outline of the process of binarizing the received light waveform, the process of integrating the received light waveform, and the process of integrating the binarized waveform.

[0017] Figure 4 This is an explanatory diagram showing the relationship between the presence of a target and the received light waveform.

[0018] Figure 5 It is an explanatory diagram showing a received light waveform when receiving irradiation light from another distance measuring device.

[0019] Figure 6 This is an explanatory diagram showing the relationship between the integrated value of the binarized waveform and the filter characteristics.

[0020] Figure 7 It is an explanatory diagram showing an outline of processing in the distance calculation unit.

[0021] Figure 8 This is a block diagram showing the configuration of a distance measuring device in a second embodiment.

[0022] Figure 9 This is an explanatory diagram showing an overview of the process of binarizing the received light waveform, the process of integrating the received light waveform, and the process of calculating the logical sum of the binarized waveforms.

[0023] Figure 10 This is a block diagram showing the configuration of a distance measuring device in a third embodiment.

[0024] Figure 11 It is an explanatory diagram showing an outline of processing by the distance calculation unit in the third embodiment.

[0025] Figure 12 This is a block diagram showing a modified example of the third embodiment.

[0026] Figure 13 This is a block diagram showing the configuration of a distance measuring device in a fourth embodiment.

[0027] Figure 14 This is an explanatory diagram showing an overview of the process of normalizing a binary waveform.

[0028] Figure 15 It is an explanatory diagram showing an outline of processing by a distance calculation unit in the fourth embodiment.

[0029] Figure 16 This is a block diagram showing the configuration of a distance measuring device in a fifth embodiment.

[0030] Figure 17 It is an explanatory diagram showing an outline of processing by a threshold setting unit in the fifth embodiment.

[0031] Figure 18 It is a block diagram showing the configuration of a distance measuring device in a sixth embodiment.

[0032] Figure 19 This is a block diagram showing the configuration of a distance measuring device in a seventh embodiment.

[0033] Figure 20 It is an explanatory diagram showing an outline of processing by a threshold setting unit in the seventh embodiment.

[0034] Figure 21 This is a block diagram showing the configuration of a distance measuring device according to an eighth embodiment.

[0035] Figure 22 It is a block diagram showing the configuration of a distance measuring device according to a ninth embodiment.

[0036] Figure 23These are explanatory diagrams showing a modified example of the process of binarizing the received light waveform, the process of integrating the received light waveform, and the outline of the process of integrating the binarized waveform.

[0037] Figure 24 This is an explanatory diagram showing an overview of a modified example of the process of binarizing the received light waveform, the process of integrating the received light waveform, and the process of calculating the logical sum of the binarized waveforms.

[0038] Figure 25 This is a block diagram showing the configuration of a distance measuring device in a tenth embodiment.

[0039] Figure 26 It is an explanatory diagram showing an outline of processing by a distance measuring unit in the tenth embodiment.

[0040] Figure 27 This is a flowchart showing the processing of the filtering unit in the tenth embodiment.

[0041] Figure 28 It is a block diagram showing the configuration of a distance measuring device in the eleventh embodiment.

[0042] Figure 29 This is a flowchart showing the processing of the detection and determination unit in the eleventh embodiment.

[0043] Figure 30 It is an explanatory diagram showing an outline of the processing of the detection and determination unit in the eleventh embodiment.

[0044] Figure 31 It is a block diagram showing the configuration of a distance measuring device in a twelfth embodiment.

[0045] Figure 32 This is a flowchart showing the processing of the effective echo extraction unit in the twelfth embodiment.

[0046] Figure 33 This is a flowchart showing a modified example of the processing of the effective echo extraction unit in the twelfth embodiment.

[0047] Figure 34 This is a block diagram showing the configuration of a distance measuring device in a thirteenth embodiment.

[0048] Figure 35 It is a block diagram showing the configuration of a distance measuring device in a fourteenth embodiment.

[0049] Figure 36 This is a flowchart showing the processing of the peak deviation calculation unit in the fourteenth embodiment.

[0050] Figure 37 It is an explanatory diagram showing an outline of processing by a peak deviation calculation unit in the fourteenth embodiment.

[0051] Figure 38 This is a flowchart showing the processing of the detection and determination unit in the fourteenth embodiment.

[0052] Figure 39 It is a block diagram showing the configuration of a distance measuring device in a fifteenth embodiment.

[0053] Figure 40 This is a flowchart showing the processing of the filtering unit in the fifteenth embodiment.

[0054] Figure 41 This is an explanatory diagram showing an outline of the steps for calculating the cumulative light reception information using the subtraction and accumulation method.

[0055] Figure 42 This is an explanatory diagram showing an outline of the steps for calculating the cumulative light reception information using the accumulation-and-subtraction method.

[0056] Figure 43 This is an explanatory diagram showing an outline of the steps for calculating the cumulative light reception information using the sequential accumulation method.

[0057] Figure 44 This is a flowchart showing the processing of the detection and determination unit in the modified example of the eleventh embodiment.

[0058] Figure 45 It is an explanatory diagram of a situation assumed in the sixteenth embodiment.

[0059] Figure 46 This is a block diagram showing the configuration of a distance measuring device in a sixteenth embodiment.

[0060] Figure 47 It is an explanatory diagram showing each light reception information and cumulative light reception information when the disturbance light peak is not included.

[0061] Figure 48 It is an explanatory diagram showing each piece of light reception information and the cumulative light reception information when the peak value of the disturbance light included in each piece of light reception information is smaller than the peak value of the reflected light.

[0062] Figure 49 It is an explanatory diagram showing each light reception information and the accumulated light reception information when the peak value of the disturbance light included in each light reception information is larger than the peak value of the reflected light.

[0063] Figure 50 It is an explanatory diagram showing each piece of light reception information and the accumulated light reception information when the peak value of the disturbance light included in the light reception information is larger than the peak value of the reflected light.

[0064] Figure 51 It is an explanatory diagram showing each light reception information, intermediate cumulative information, and cumulative light reception information in a modification example of the sixteenth embodiment.

[0065] Figure 52 This is an explanatory diagram showing a case where a distance measuring device includes a plurality of light emitting units, each of which irradiates light in a different direction.

[0066] Figure 53 This is an explanatory diagram showing the light emission timing when the output cycles of the two light emitting units are randomly changed.

[0067] Figure 54 This is an explanatory diagram showing the light emission timing when two light emitting units are each made to emit light at a constant output period and the output period of each light emitting unit is made different.

[0068] Figure 55 This is a block diagram showing the configuration of a modified example of the distance calculation unit.

[0069] Figure 56 It means in Figure 55 1 is an explanatory diagram of an overview of the processing of the distance calculation unit shown.

[0070] Figure 57 This is a block diagram showing the configuration of a modified example of the distance calculation unit.

[0071] Figure 58 It means in Figure 57 1 is an explanatory diagram of an overview of the processing of the distance calculation unit shown. DETAILED DESCRIPTION

[0072] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0073] [1. First embodiment]

[0074] [1-1. Composition]

[0075] Figure 1 The distance measuring device 1 shown is a so-called laser radar device mounted on a vehicle. It irradiates light, receives light reflected from objects that reflect the irradiated light, and measures the distance based on the round-trip time it takes for the light to reach the object being measured. Laser radar is also referred to as LIDAR. LIDAR stands for Light Detection and Ranging.

[0076] like Figure 1 As shown, the distance measuring device 1 includes a light emitting unit 2 , a light receiving unit 3 , a timing control unit 4 , and a processing unit 5 .

[0077] The light emitting unit 2 includes one or more light emitting elements and repeatedly emits pulsed laser light in response to a light emission trigger signal from the timing control unit 4. For example, a laser diode is used as the light emitting element.

[0078] The light receiving unit 3 has a plurality of SPADs and photodetectors arranged in a two-dimensional manner. SPAD is a Single Photon Avalanche Diode: an abbreviation of a single-photon avalanche diode. SPAD is an avalanche photodiode (hereinafter referred to as APD) that operates in Geiger mode. Geiger mode is an operation mode in which a reverse bias voltage higher than the breakdown voltage is applied to the APD to make it operate. The SPAD breaks down due to the incidence of photons. The photodetector detects the voltage change when the SPAD breaks down, outputs a digital pulse of a specified pulse width, and summarizes the number of pulses detected according to a pre-set unit time. Based on the summary result, light receiving information representing the relationship between time and light amount is generated by sampling the light receiving amount for a certain period with the light emission timing as the starting moment. In addition, the waveform represented by the light receiving information is called a light receiving waveform.

[0079] like Figure 2 As shown, the timing control unit 4 repeatedly outputs the light trigger signal. The output period T1, T2, T3, ... of the light trigger signal is not constant, but varies randomly within a constant range. The constant range is set to be longer than the time Tmax required for light to reciprocate at the maximum detection distance of the distance measuring device 1, and is set to be a range in which multiple light receiving information that becomes the object of accumulation described later is regarded as information measured for an object located at the same position. Figure 2 In the example, a preset reference time is set as Tf, Tmax is set to be less than 5Tf, and the period is changed in units of the reference time Tf. Hereinafter, the timing of outputting the light emission trigger signal is referred to as light emission timing.

[0080] Return to Figure 1 The processing unit 5 includes a light receiving integrating unit 6 , a characteristic setting unit 7 , and a distance calculating unit 8 .

[0081] like Figure 3 As shown, the light reception integrating section 6 integrates M pieces of light reception information obtained at M consecutive light emission timings supplied from the light receiving section 3 by aligning the time with the light emission timing as a starting point. Figure 3 The case of M = 3 is shown. The M pieces of light reception information that are integrated by the light reception integration unit 6 are referred to as a target information group. The result of integration by the light reception integration unit 6 is referred to as integrated light reception information, and the waveform represented by the integrated light reception information is referred to as an integrated light reception waveform. The integrated light reception information is supplied to the distance calculation unit 8.

[0082] In addition, if Figure 3 as well as Figure 4As shown, when an object actually exists, a pulse-shaped waveform (hereinafter referred to as a reflected light waveform) based on reflected light from the same object is detected in approximately the same time range on the time axis starting from the emission timing in all the received light waveforms indicated by the M light receiving information. Furthermore, the reflected light from the object corresponds to non-interference light.

[0083] In addition, if Figure 3 as well as Figure 5 As shown, in addition to the existence of an object, when pulsed interference light is received from the outside that is independent of the irradiation light emitted at the luminous timing of the distance measuring device 1, a pulsed waveform (hereinafter referred to as the interference light waveform) is detected in addition to the reflected light waveform. In addition, the pulsed interference light includes the irradiation light from other distance measuring devices. The interference light waveform is not generated in all of the M light receiving information but appears singly. In addition, when the source of the interference light is other distance measuring devices 1 mounted on other vehicles, etc., or other distance measuring devices that repeatedly emit and receive light according to the same principle as the distance measuring device 1 in the present invention, there is a possibility that an interference light waveform will be generated in every M light receiving information. However, since the luminous timing varies randomly in each distance measuring device 1, the interference light waveform is detected in a time range different from the reflected light waveform on the time axis starting from the luminous timing. Figure 3 , a case where the disturbance light waveform is detected only in the second of three times is shown.

[0084] By integrating the light reception information in the light reception integrating unit 6 , the amplitude of the reflected light waveform detected at substantially the same position each time is increased, and the amplitude of the disturbance light waveform detected singly is suppressed.

[0085] Return to Figure 1 The characteristic setting unit 7 includes a binarization unit 71 and a filter generation unit 72 .

[0086] like Figure 3 As shown, the binarization unit 71 binarizes the light waveform represented by the M light reception information accumulated by the light reception accumulation unit 6 using a predetermined binarization threshold THb to generate binary light reception information. For the binary waveform represented by the binary light reception information, the value (i.e., the amplitude of the waveform) is 1.0 during the time range in which the signal intensity of the light reception waveform represented by the light reception information exceeds the binarization threshold THb, and the value is 0 during the time range in which the signal intensity is below the binarization threshold THb. The binarization threshold THb is set, for example, to the lower limit of the range of the amount of light received by the interference light. Furthermore, the binarization threshold THb is not limited to a predetermined fixed value; for example, a variable value calculated based on the light reception information may be used.

[0087] The filter generation unit 72 includes a binary integration unit 721 and a determination unit 722 .

[0088] The binary accumulation section 721 accumulates the M pieces of binary information of light reception generated by the binarization section 71 on the time axis that matches the light emission timing. For the accumulated binary waveform shown by the accumulated binary information, the value (i.e., the amplitude of the waveform) within the time range of the reflected light waveform is M, and the value within the time range of the interference light waveform is smaller than M. Figure 3 The number in the middle is 1.

[0089] like Figure 6 As shown, based on the accumulated binary information generated by the binary accumulation unit 721, the determination unit 722 binarizes the accumulated binary waveform represented by the accumulated binary information using a determination threshold THj set to a value smaller than M. Based on the binarization result, the determination unit 722 extracts the estimated valid range within which the reflected light waveform is detected and supplies it to the distance calculation unit 8. Furthermore, the range where the interfering light is received during the time period outside the valid range is referred to as the invalid range. In other words, the invalid range corresponds to the designated range. In addition to being set based on the accumulated number M as described above, the determination threshold THj may also be a pre-set fixed threshold.

[0090] Return to Figure 1 The distance calculation unit 8 includes a distance measuring unit 81 and a filtering unit 82.

[0091] like Figure 7 As shown, based on the accumulated light reception information, the distance measuring unit 81 calculates the light reception timing for each pulse-shaped waveform having a peak value greater than an extraction threshold value THe set at or above the minimum intensity to be detected. The extraction threshold value THe is set at or above the minimum intensity to be detected. The extraction threshold value THe is, for example, set to a value greater than the binarization threshold value THb and less than the determination threshold value THj, but is not limited to this setting.

[0092] Furthermore, the distance measuring unit 81 calculates the distance to the object that has reflected the irradiated light based on the time difference between the light emission timing and the light reception timing. In addition, the light reception timing may be the timing at which the peak is actually obtained, or the timing at which the signal level is in the middle of a range above a certain threshold. In addition, the light emission timing may be the timing of the peak estimated using an interpolation method based on the discretely obtained signal level. In addition, the distance calculated by the distance measuring unit 81 is not limited to one. The result of the processing in the distance measuring unit 81 calculates not only the distance based on the reflected light waveform, but also the distance based on the interference light waveform. Hereinafter, the information related to the peak detected by the distance measuring unit 81 using the extraction threshold THe is referred to as echo information EC, and is expressed in order from near to far as EC(1), EC(2), ... In addition to the distance, the echo information EC(i) may also include the peak value in the cumulative light reception waveform.

[0093] The filter unit 82 converts the effective range on the time axis extracted by the determination unit 722 into an effective range on the distance axis (hereinafter referred to as the effective distance range). This conversion can also be performed in the determination unit 722. Furthermore, the filter unit 82 uses the extraction threshold THe to extract echo information EC having a peak value greater than the extraction threshold THe from the accumulated light reception information. For each extracted echo information EC, the filter unit 82 determines whether the calculated distance calculated by the distance measuring unit 81 is within the effective distance range. If the filter unit 82 determines that the calculated distance is not within the effective distance range, it discards the calculated distance. If the calculated distance is within the effective range, it outputs the calculated distance as the distance to the actual object. This processing in the filter unit 82 is referred to as filtering. In other words, the filter characteristics are set according to the effective range extracted by the determination unit 722.

[0094] [1-2. Effect]

[0095] According to the first embodiment described in detail above, the following effects are achieved.

[0096] (1a) In this embodiment, the distance to the object that reflected the irradiated light is calculated using the accumulated light reception information obtained by accumulating M light reception information. Therefore, it is possible to suppress noise randomly generated in the light reception information and to suppress erroneous detection caused by the noise.

[0097] (1b) In the present embodiment, binary information is generated by binarizing M pieces of light-receiving information using a binarization threshold THb. Furthermore, the cumulative binary information of the cumulatively generated M pieces of binary information is binarized using a judgment threshold THj, and the effective range in which the reflected light waveform is estimated to exist is extracted. Then, the distance included in the effective range among the distances calculated for each pulse-shaped waveform in the distance measuring unit 81 is output as the distance to the object. In other words, the distance included in the invalid range (i.e., the specified range) outside the effective range is discarded. Therefore, according to the present embodiment, it is possible to suppress erroneous detection based on the interference light waveform, that is, the situation where the distance is detected even though there is no object.

[0098] In other words, even if the interference light waveform is detected only once in the accumulated light reception information, if the signal level of that single shot is high, a peak value equal to or greater than that of the reflected light waveform can be obtained. Therefore, in some cases, it is difficult to distinguish between the reflected light waveform and the interference light waveform in the accumulated light reception information. In contrast, the accumulated binary information does not care about the signal level of the waveform shown in the light reception information, but rather obtains an amplitude corresponding to the accumulated value, making it possible to distinguish between the reflected light waveform and the interference light waveform.

[0099] (1c) In this embodiment, the distance to an object is calculated using M pieces of light-receiving information measured by randomly varying the timing of light emission. Therefore, interference light waveforms having pulsed waveforms, such as light emission from other distance-measuring devices mounted on other vehicles, are detected at different times from the reflected light waveform within the M pieces of light-receiving information being accumulated. This improves the detection accuracy within the effective range based on the accumulated binary information.

[0100] [2. Second embodiment]

[0101] [2-1. Differences from the First Embodiment]

[0102] The basic structure of the second embodiment is the same as that of the first embodiment, so the following description will focus on the differences.

[0103] In the second embodiment, the configuration of the characteristic setting unit 7a in the processing unit 5a is different from that in the first embodiment. Specifically, the configuration of the filter generating unit 72a in the characteristic setting unit 7a is different. Figure 8 As shown, the filter generation unit 72 a includes a logical operation unit 723 instead of the binary integration unit 721 and the determination unit 722 .

[0104] like Figure 9 As shown, the logic operation unit 723 extracts the effective range by performing a logical AND operation on the M binary information generated by the binarization unit 71. This logical AND operation can extract the range where the signal is detected in all the M binary information as the effective range.

[0105] [2-2. Effect]

[0106] According to the second embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effects (2a) to (2c) are also achieved.

[0107] (2a) In this embodiment, the same effective range as in the first embodiment is extracted, so that erroneous detection based on the disturbance light waveform, that is, distance detection even when no object is present, can be suppressed.

[0108] (2b) In this embodiment, the distance to an object is calculated using M pieces of light-receiving information measured by randomly varying the light emission timing. Therefore, interfering light waveforms having pulsed waveforms, such as light emission from other distance-measuring devices, are detected at times different from the reflected light waveform in the M pieces of light-receiving information subject to the logical AND operation, thereby improving the detection accuracy of the effective range of the logical operation unit 723.

[0109] (2c) In this embodiment, the same effective range as in the first embodiment can be extracted by simpler processing than in the first embodiment, so the processing load on the processing unit 5a can be reduced.

[0110] [3. Third embodiment]

[0111] [3-1. Differences from the First Embodiment]

[0112] The basic structure of the third embodiment is the same as that of the first embodiment, so the following description will focus on the differences.

[0113] In the third embodiment, the configuration of the distance calculation unit 8b in the processing unit 5b is different from that in the first embodiment. Specifically, in the first embodiment, the filtering process of the filtering unit 82 is performed on the result of the distance measurement process in the distance measurement unit 81. In contrast, in the second embodiment, Figure 10 As shown, the integrated light reception information from the light reception integrating unit 6 is subjected to filtering processing by the filtering unit 82 b , and the result of the filtering processing is subjected to distance measurement processing by the distance measuring unit 81 .

[0114] In other words, Figure 11 As shown, filtering unit 82b filters the accumulated received light waveform on the time axis to extract the signal waveform for the time range corresponding to the effective period, while removing the signal waveform for the time range corresponding to the ineffective period, which is a period other than the effective period. Distance measuring unit 81 then performs distance measurement on only the pulse-shaped waveform extracted by the filtering process, i.e., the reflected light waveform, to generate echo information EC containing the distance to the object.

[0115] [3-2. Effect]

[0116] According to the third embodiment described in detail above, the effects (1a) to (1c) of the first embodiment described above are achieved, and the following effects are achieved.

[0117] (3a) According to this embodiment, the disturbance light waveform is removed before the processing of the distance measuring unit 81 , so the processing load of the distance measuring unit 81 can be reduced.

[0118] [3-3. Modification]

[0119] In the third embodiment, the characteristic setting unit 7 and the distance calculation unit 8b described in the first embodiment are combined as the processing unit 5b, but it is also possible to Figure 12 As shown in the processing unit 5c, the characteristic setting unit 7a and the distance calculation unit 8b described in the second embodiment are combined.

[0120] [4. Fourth embodiment]

[0121] [4-1. Differences from the First Embodiment]

[0122] The basic structure of the fourth embodiment is the same as that of the first embodiment, so the following description will focus on the differences. The same reference numerals as those in the first embodiment denote the same structure, and reference will be made to the preceding description.

[0123] In the fourth embodiment, the configuration of the characteristic setting unit 7d and the distance calculation unit 8b in the processing unit 5d is different from that in the first embodiment. Specifically, the configuration of the filter generation unit 72d in the characteristic setting unit 7d is different. Figure 13 As shown, the filter generation unit 72d omits the determination unit 722 compared to the filter generation unit 72 of the first embodiment and instead includes a normalization unit 724. Furthermore, in the fourth embodiment, the distance calculation unit 8 is replaced with the distance calculation unit 8b described in the third embodiment.

[0124] like Figure 14 As shown, the normalization unit 724 generates normalized information by dividing the cumulative value indicated by the accumulated binary information obtained by the binary accumulation unit 721 by the number of light reception information to be accumulated by the light reception accumulation unit 6, that is, the accumulation number M. In other words, the signal level of the normalized information is 1.0 within the range where signals are detected by all the accumulated light reception information, and the signal level of the normalized information is 1 / M within the range where a signal is detected by only one light reception information.

[0125] In the filter portion 82b, as Figure 15 As shown, the signal level indicated by the normalized information is used as a gain and multiplied by the accumulated light reception information. By multiplying the accumulated light reception information by the gain, the peak of the waveform can be further suppressed in the range where a pulse-like waveform is detected individually, increasing the likelihood of further reducing the extraction threshold value The. As a result, the distance measuring unit 81 is less likely to perform distance measurement processing on pulse-like waveforms falling within the low-gain range.

[0126] [4-2. Effect]

[0127] According to the fourth embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effects (4a) to (4c) are also achieved.

[0128] (4a) In this embodiment, in addition to the same effective range as in the first embodiment, an effective range with a gain smaller than 1 is also extracted. Therefore, not only can false detection based on the interference light waveform, that is, the detection of the distance even though there is no object, be suppressed, but the distance can also be calculated for the pulse waveform detected in the same range at a high frequency, though not every time.

[0129] (4b) In this embodiment, the distance is calculated using M pieces of light-receiving information measured by randomly varying the light emission timing. Therefore, in the M pieces of light-receiving information, an interference light waveform having a pulsed waveform, such as light emission from another distance-measuring device, is detected at a different time than the reflected light waveform. This allows the gain of the normalized information within the range where the interference light waveform is detected to be sufficiently suppressed.

[0130] (4c) According to this embodiment, the possibility of removing the disturbance light waveform increases by the filtering process before the processing of the distance measuring unit 81, so the processing load on the distance measuring unit 81 can be reduced.

[0131] [4-3. Modification]

[0132] In the first to fourth embodiments, the filter unit 82 performs filtering on the distance to the object calculated by the distance measuring unit 81 , and the filter unit 82 b performs filtering on the integrated light receiving waveform on the time axis calculated by the light receiving integrating unit 6 .

[0133] When the distance measuring unit 81 calculates the light receiving timing, if it uses the data required for calculating the half-value width and intermediate data such as a plurality of discrete signal levels near the peak, Figures 55 to 58 As shown, the intermediate data can also be filtered.

[0134] For example, Figure 55 The distance calculation unit 8q shown includes a pre-distance measuring unit 81q, a filtering unit 82, and a post-distance measuring unit 83q.

[0135] The pre-distance measuring unit 81q extracts the timing required for calculating the intermediate data on the time axis and converts the extracted timing into distance data. Figure 56 , a case is shown where the half-value width distance, which is distance data calculated based on the timing of obtaining the half-value level of the peak required for calculating the half-value width, is extracted.

[0136] The filter unit 82 performs filtering processing on the distance axis to extract the half-value width distance of the peak correlation to be the generation target of the echo information EC.

[0137] The post-distance measuring unit 83 q calculates the distance to the object that reflected the irradiated light using the half-value width distance extracted by the filtering unit 82 .

[0138] in addition, Figure 57 The distance calculation unit 8r shown includes a pre-distance measuring unit 81r, a filtering unit 82b, and a post-distance measuring unit 83r.

[0139] The pre-distance measuring unit 81r extracts the timing required for calculating the intermediate data on the time axis. Figure 58, a case where the half-value width time, which is the timing of the half-value level of the peak required for calculation of the half-value width, is extracted is shown.

[0140] The filter unit 82b performs filtering processing on the half-value width time extracted by the pre-ranging unit 81r on the time axis, and extracts the half-value width time of the peak correlation to be the target of generating the echo information EC.

[0141] The post-distance measuring unit 83 r converts the half-value width time extracted by the filtering unit 82 b into distance data, and uses the converted distance data to calculate the distance to the object that reflected the irradiated light.

[0142] exist Figure 56 as well as Figure 58 In the example, the case of using the half-value width as the intermediate data is illustrated. However, the intermediate data is not limited to the half-value width, and any data may be time data or distance data extracted from pulses exceeding the extraction threshold value THe, such as the peak time of the pulse.

[0143] [5. Fifth embodiment]

[0144] [5-1. Differences from the First Embodiment]

[0145] The basic structure of the fifth embodiment is the same as that of the first embodiment, so the following description focuses on the differences. The same reference numerals as those of the first embodiment denote the same structures, and reference is made to the preceding description.

[0146] In the fifth embodiment, the configurations of a characteristic setting unit 7e and a distance calculation unit 8e in a processing unit 5e are different from those in the first embodiment.

[0147] like Figure 16 As shown, the characteristic setting unit 7e includes a baseline calculation unit 73, a peak calculation unit 74, and a threshold setting unit 75.

[0148] The baseline calculation unit 73 calculates an independent baseline value representing the value of the baseline according to each of the multiple light receiving information that becomes the object of accumulation in the light receiving accumulation unit 6. In addition, the baseline refers to the amount of light received as compensation after removing the influence of reflected light based on the irradiated light, the influence of interference light from other laser radar devices, etc., and the influence of clutter. Clutter is the light receiving noise generated near the zero distance when the radiated light is reflected and received by the shell of the ranging device 1. The value of the baseline can also be used, for example, the average value or median value of the amount of light received detected within the time range after removing the time range affected by the reflected light, interference light, and clutter. The baseline is also called the background noise level. In the following, N m Indicates the independent baseline value in the mth light reception information. m = 1, 2, ..., M.

[0149] The baseline calculation unit 73 calculates a cumulative baseline value representing the value of the baseline in the cumulative light reception information. The cumulative baseline value Ns can be calculated based on the cumulative light reception information in the same manner as the independent baseline value, or by adding the independent baseline values ​​(i.e., Ns = N1 + N2 + ... + N M ) to calculate.

[0150] The peak value calculation unit 74 obtains the maximum light intensity for each light receiving information. Figure 17 As shown, both the received light waveform and the interference light waveform are selected. In addition, the maximum received light amount can be obtained from the full time range indicated by the received light information, for example, it can also be obtained from the time range after excluding the time range of the detected clutter. Hereinafter, the maximum received light amount in the mth received light information is referred to as the original peak value A. m The peak value calculation unit 74 also calculates the peak value A of each of the M light receiving information. m Subtract the independent baseline value N m , calculate the relative peak value S of the light waveform m In addition, at the relative peak S m In the calculation of , it can also replace the independent baseline value N m , and use the value obtained by dividing the cumulative baseline value Ns by the cumulative number M.

[0151] The threshold setting unit 75 includes a maximum extraction unit 751 .

[0152] The maximum extraction unit 751 extracts the M relative peak values ​​S1 to S2 calculated by the peak calculation unit 74. M The maximum value in the maximum relative peak value Smax=MAX(S1, S2, ..., S M ). Then, the maximum extraction unit 751 sets the value obtained by adding the difference α to the maximum peak relative value Smax and the cumulative baseline value Ns as the extraction threshold THe. The difference α may also be omitted.

[0153] The distance calculation unit 8e includes a distance measuring unit 81e. Using the accumulated light reception information, the distance measuring unit 81e extracts pulse waveforms having a peak value greater than the extraction threshold value THe set in the threshold setting unit 75. Based on the reception timing of each of the extracted pulse waveforms, the distance to the object is calculated. In other words, the distance measuring unit 81e differs from the distance measuring unit 81 in that the setting of the extraction threshold value THe can be changed. The unit then generates and outputs echo information EC that associates the calculated distance with the peak value.

[0154] [5-2. Effect]

[0155] According to the fifth embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effect (5a) is achieved.

[0156] (5a) In this embodiment, the extraction threshold THe used to extract the pulse waveform to be processed for distance measurement is set based on the maximum relative peak value Smax extracted from the M pieces of light-receiving information. Therefore, according to this embodiment, false detection based on the interference light waveform, i.e., detecting the distance despite the absence of an object, can be suppressed. Furthermore, ranging processing of the interference light waveform can be suppressed, thereby reducing the processing load of the distance measuring unit 81e. Furthermore, while the first to fourth embodiments require memory for filters corresponding to the time range, this embodiment only requires memory corresponding to the maximum relative peak value Smax, thereby reducing the amount of memory required for installation.

[0157] In other words, Figure 17 As shown, even when the peak value of the interference light waveform is larger than the peak value of the reflected light waveform, as long as the interference light waveform is not detected at the same time in multiple light receiving information W(1) to W(M), the peak value of the interference light waveform in the accumulated light receiving information will not exceed the extraction threshold value THe. Therefore, it is possible to perform distance measurement after removing the interference light waveform using the extraction threshold value THe.

[0158] [5-3. Modification]

[0159] In this embodiment, the light receiving integration unit 6 simply calculates the integrated light receiving information by adding a plurality of light receiving information W(1) to W(M). m The sum of the received light information becomes the cumulative baseline value Ns, but the method of accumulating the received light information is not limited to simple addition. For example, the received light accumulating unit 6 may be configured to accumulate the plurality of received light information W(1) to W(M) so that the cumulative baseline value Ns becomes zero. Hereinafter, the accumulated received light information accumulated so that Ns=0 is referred to as zero-based accumulated received light information, and the accumulated received light information accumulated so that Ns≠0 is referred to as non-zero-based accumulated received light information.

[0160] Specifically, if Figure 41 As shown, the light receiving integrating unit 6 calculates the independent baseline values ​​N1 to N2 for each light receiving information W(1) to W(M). m Then, the light receiving integrating unit 6 subtracts the independent baseline value N from each light receiving information W(m). m The result after (W(m)-N m ) are added to calculate the zero-based cumulative light receiving information. Hereinafter, this method is referred to as the subtraction and accumulation method.

[0161] like Figure 42 As shown, the light receiving integration unit 6 subtracts the independent baseline values ​​N1 to N2 from the result ΣW(m) obtained by simply adding the light receiving information W(1) to W(M). MThe zero-based cumulative light reception information is calculated using the total value Nsum of ΣW(m). Instead of Nsum, the baseline value extracted from ΣW(m) can be used for subtraction. This method is hereinafter referred to as the accumulation-subtraction method.

[0162] like Figure 43 As shown, the light receiving integration unit 6 can also calculate the zero-based integrated light receiving information in the following order. That is, the first light receiving information is used as the first intermediate integrated information. Assuming i = 2 to M, the independent baseline value N extracted from the i-1th light receiving information is subtracted from the i-1th intermediate integrated information. i－1 The ith intermediate cumulative information is calculated by adding the result after the ith light receiving information. Then, the independent baseline value N extracted from the Mth light receiving information is subtracted from the Mth intermediate cumulative information. M , calculate the zero-based cumulative light receiving information. Hereinafter, this method is referred to as the zero-based sequential accumulation method.

[0163] In the above description, the independent baseline value N is subtracted from the i-1th intermediate cumulative information. i－1 After that, the i-th light receiving information is added, but the order of calculation is not limited to this. For example, the independent baseline value N may be subtracted from the result of adding the i-1-th intermediate cumulative information to the i-th light receiving information. i－1 wait.

[0164] In addition, the Mth intermediate cumulative information is used as the cumulative light receiving information, and the independent baseline value N extracted from the Mth light receiving information is used as the cumulative light receiving information. M The method of accumulating the baseline value Ns is called the non-zero-based sequential accumulation method.

[0165] When the light receiving integration unit 6 is configured to calculate the integrated light receiving information with Ns=0, that is, zero-based integrated light receiving information, the extraction threshold value The may be set using any of the following methods (1) to (3).

[0166] THe=Smax (1)

[0167] THe=Amax-Nx (2)

[0168] THe=Amax-Nave (3)

[0169] Among them, Amax is the M original peak values ​​A1~A M The maximum value MAX(A1, A2, ..., A M ), is called the maximum original peak value. Nx is the independent baseline value in the light receiving information that becomes the extraction source of the maximum original peak value Amax. Nave is M independent baseline values ​​N1~N M The average value AVE(N1, N2, ..., N M). In addition, in equations (1) to (3), a difference value α may be added to the extraction threshold value The. In addition, Nx in (2) and Nave in equation (3) correspond to the compensation value.

[0170] The light receiving integrating unit 6 is configured to use a non-zero-based sequential integrating method to calculate Ns=N M In the case of the cumulative light receiving information, that is, the non-zero-based cumulative light receiving information, the extraction threshold THe can also be set using any one of the methods shown in the following equations (4) to (7).

[0171] THe=Smax+N M (4)

[0172] THe=Amax-Nx+N M (5)

[0173] THe=Amax-Nave+N M (6)

[0174] THe=Amax (7)

[0175] Formulas (4) to (6) are the sum of Formulas (1) to (3) plus the independent baseline value N of the Mth light receiving information, which becomes the cumulative baseline value Ns. M The following formula is obtained. Formula (7) is obtained by assuming that Nx=N in formula (5). M The obtained approximate formula can simplify the calculation of the threshold value THe. In addition, in formulas (4) to (7), the difference α can be added to the extraction threshold value The.

[0176] Here, the independent baseline value N of the Mth light receiving information is M While the method for forming the cumulative baseline value Ns of the non-zero-based cumulative light reception information has been described for the case of cumulative light reception information, the method of accumulating light reception information is not limited thereto. For example, a configuration may be employed in which the cumulative baseline value Ns is formed by an arbitrarily selected independent baseline value of light reception information. Alternatively, a configuration may be employed in which the sum of the independent baseline values ​​of any arbitrarily selected light reception information is formed as the cumulative baseline value.

[0177] In addition, use Figures 41 to 43 The processing of the light receiving integrating unit 6 described above is applicable not only to the sixth embodiment and subsequent embodiments but also to the light receiving integrating unit 6 in the first to fourth embodiments.

[0178] [6. Sixth embodiment]

[0179] [6-1. Differences from the First Embodiment]

[0180] The basic structure of the sixth embodiment is the same as that of the first embodiment, so the following describes the differences. In addition, the same reference numerals as those of the first embodiment represent the same structure, and reference is made to the previous description.

[0181] In the sixth embodiment, the configurations of the characteristic setting unit 7f and the distance calculation unit 8e in the processing unit 5f are different from those in the first embodiment. However, the distance calculation unit 8e is the same as the distance calculation unit described in the fifth embodiment.

[0182] like Figure 18 As shown, the characteristic setting unit 7f generates an extraction threshold value THe based on the integrated light reception information supplied from the light reception integration unit 6. The characteristic setting unit 7f includes a baseline calculation unit 73f, a peak calculation unit 74f, and a threshold value setting unit 75f.

[0183] The baseline calculation unit 73f calculates the cumulative baseline value Ns, which represents the baseline value of the cumulative light reception information calculated by the light reception integration unit 6. The cumulative baseline value Ns may be a value extracted from the cumulative light reception information, or may be an independent baseline value N1 to N2 extracted from a plurality of light reception information to be integrated by the light reception integration unit 6. M The peak calculation unit 74f calculates the relative peak value S of the cumulative light reception information by extracting the maximum value from the cumulative light reception information and subtracting the cumulative baseline value Ns calculated by the baseline calculation unit 73f from the extracted maximum value.

[0184] The threshold setting unit 75 f includes a division unit 752 .

[0185] The division unit 752 divides the relative peak value S of the accumulated light reception information calculated by the peak value calculation unit 74f by the number of light reception information to be accumulated by the light reception accumulation unit 6, that is, the accumulated number M. The division unit 752 then adds the difference value α and the accumulated baseline value Ns calculated by the baseline calculation unit 73f to the division result and sets the value as the extraction threshold value THe. Specifically, the extraction threshold value THe is set according to equation (8). The difference value α can be, for example, either a pre-specified constant or a value calculated based on the division value S / M. Alternatively, the difference value α can be omitted and the extraction threshold value THe can be set according to equation (9).

[0186] THe=S / M+α+Ns (8)

[0187] THe=S / M+Ns (9)

[0188] In a situation where it is clear that the peak value of the disturbance light waveform does not exceed the peak value of the reflected light waveform in each light reception information, the extraction threshold value THe set in this way may be used.

[0189] [6-2. Effect]

[0190] According to the sixth embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effect (6a) is achieved.

[0191] (6a) In this embodiment, the characteristic setting section 7f is provided after the light receiving integration section 6. This eliminates the need to perform calculations each time light receiving information is integrated. Instead, calculations only need to be performed on the integrated light receiving information, thereby reducing the amount of calculations.

[0192] [6-3. Modification]

[0193] When the light reception integration unit 6 is configured to calculate the integrated light reception information with Ns=0, the threshold setting unit 75f may set the extraction threshold THe based on equation (10) or (11).

[0194] THe=S / M+α (10)

[0195] THe=S / M (11)

[0196] [7. Seventh embodiment]

[0197] [7-1. Differences from the First Embodiment]

[0198] The basic structure of the seventh embodiment is the same as that of the first embodiment, so the following description will focus on the differences. The same reference numerals as those in the first embodiment denote the same structure, and reference is made to the previous description.

[0199] In the seventh embodiment, the configurations of the characteristic setting unit 7g and the distance calculation unit 8e in the processing unit 5g are different from those in the first embodiment. However, the distance calculation unit 8e is the same as the distance calculation unit described in the fifth embodiment.

[0200] like Figure 19 As shown, the characteristic setting unit 7g includes a baseline calculation unit 73g, a peak calculation unit 74, and a threshold setting unit 75g.

[0201] The baseline calculation unit 73g is the same as the baseline calculation unit 73, and calculates the independent baseline value N for each of the M light receiving information. m , and calculates the cumulative baseline value Ns. The baseline calculation unit 73g also calculates the independent baseline value N m As a parameter representing the deviation, for example, the standard deviation can also be used.

[0202] The threshold setting unit 75 g includes a maximum extraction unit 751 , a deviation calculation unit 753 , and a threshold selection unit 754 .

[0203] The maximum extraction unit 751 is similar to the maximum extraction unit described in the fifth embodiment, and calculates the maximum relative peak value Smax.

[0204] The deviation calculation unit 753 calculates the deviation σ by multiplying the average of the standard deviations of the independent baseline values ​​calculated by the baseline calculation unit 73g for each of the M light receiving information by the square root of M. The deviation σ is then multiplied by G times σ as the allowable deviation value. G is a positive real number. G is appropriately set depending on the probability of causing noise to be mistakenly detected as an object. Here, the deviation σ is calculated using the independent baseline values ​​N1 to N2 calculated for each of the M light receiving information. M The value obtained by multiplying the average value of the standard deviation by the square root of M can be used, but the standard deviation of the cumulative baseline value calculated based on the light reception cumulative information can also be used.

[0205] like Figure 20 As shown, threshold selection unit 754 compares the value obtained by adding the difference α to the maximum peak relative value Smax, the allowable deviation value G×σ, and a predetermined fixed value D. Fixed value D is set, for example, so that even when the deviation σ is extremely small, such as in a closed space, an appropriate extraction threshold value THe is obtained. If Smax+α is maximized, extraction threshold value THe is set according to equation (12). If G×σ is maximized, extraction threshold value THe is set according to equation (13). If D is maximized, extraction threshold value THe is set according to equation (14).

[0206] THe=Smax+α+Ns (12)

[0207] THe=G×σ+Ns (13)

[0208] THe=D+Ns (14)

[0209] Furthermore, equation (12) may be replaced by the extraction threshold THe calculated using equations (4) to (7), or by the extraction threshold THe calculated by adding the difference α to the right side of equations (5) to (7).

[0210] [7-2. Effect]

[0211] According to the seventh embodiment described in detail above, the effect (1a) of the first embodiment and the effect (5a) of the fifth embodiment described above are achieved, and the following effect (7a) is also achieved.

[0212] (7a) In this embodiment, the extraction threshold value THe is switched based on a comparison between the allowable deviation value G×σ calculated from the deviation σ of the baseline value, the maximum peak value Smax+α, and the fixed value D. By switching the extraction threshold value THe, even when the disturbance light waveform is buried in noise, it is possible to suppress the noise from being erroneously detected as a reflected light waveform. Furthermore, even when the deviation σ of the baseline value is extremely small, it is possible to set an appropriate extraction threshold value THe.

[0213] [7-3. Modification]

[0214] When the light receiving integration unit 6 is configured to integrate a plurality of light receiving information so that the integrated baseline value Ns becomes zero, the threshold setting unit 75g may use the extraction threshold THe calculated using the equation obtained by removing the integrated baseline value Ns from the right side of equations (12) to (14).

[0215] [8. Eighth embodiment]

[0216] [8-1. Differences from the First Embodiment]

[0217] The basic structure of the eighth embodiment is the same as that of the first embodiment, so the following describes the differences. In addition, the same reference numerals as those of the first embodiment represent the same structure, and reference is made to the previous description.

[0218] In the eighth embodiment, as Figure 21 As shown, the configurations of a characteristic setting unit 7h and a distance calculating unit 8h in a processing unit 5h are different from those in the first embodiment.

[0219] The characteristic setting unit 7 h includes a first setting unit 91 and a second setting unit 92 .

[0220] The first setting unit 91 has the same configuration as any of the characteristic setting units 7 , 7 a , and 7 d described in the first to fourth embodiments, and sets an effective range in which a reflected light waveform may exist.

[0221] The second setting unit 92 has the same configuration as any of the characteristic setting units 7e to 7g described in the fifth to seventh embodiments, and sets the extraction threshold THe. If the characteristic setting unit 7f of the sixth embodiment is used as the second setting unit 92, the output of the received light integrating unit 6 becomes the input to the second setting unit 92.

[0222] The distance calculation unit 8h includes two distance measuring units 81 and 81e, a filtering unit 82, and a switching unit 83.

[0223] The distance measuring unit 81 and the filtering unit 82 operate in the same manner as the distance calculating unit 8 described in the first embodiment. The distance measuring unit 81 corresponds to a first distance measuring unit, and the distance measuring unit 81 and the filtering unit 82 correspond to a first processing unit.

[0224] The distance measuring unit 81e operates in the same manner as the distance calculating unit 8e described in the fifth embodiment. The distance measuring unit 81e corresponds to a second distance measuring unit and a second processing unit.

[0225] The switching unit 83 outputs either the first distance measurement result output from the filtering unit 82 or the second distance measurement result output from the distance measuring unit 81 e according to a preset switching condition.

[0226] The switching condition can be, for example, a setting of a separately provided switch, with one of the distance measurement results fixedly output according to the setting. Alternatively, a distance threshold can be used as the switching condition, with the second distance measurement result output for a short distance range closer than the distance threshold, and the first distance measurement result output for a long distance range greater than the distance threshold. In this case, the distance measuring unit 81 can be fed with accumulated light reception information for a time range corresponding to the long distance range, while the distance measuring unit 81e can be fed with accumulated light reception information for a time range corresponding to the short distance range.

[0227] [8-2. Effect]

[0228] According to the eighth embodiment described in detail above, the configuration of the first setting unit 91 and the second setting unit 92 achieves the effects of the first to seventh embodiments and also provides the following effect (8a).

[0229] (8a) In this embodiment, the processing method in the distance calculation unit 8h can be switched according to the generation status of interference waves, etc., so the required number of memories can be reduced and the interference wave removal performance can be improved.

[0230] [9. Ninth embodiment]

[0231] [9-1. Differences from the First Embodiment]

[0232] The basic structure of the ninth embodiment is the same as that of the first embodiment, so the following describes the differences. In addition, the same reference numerals as those of the first embodiment represent the same structure, and reference is made to the previous description.

[0233] In the ninth embodiment, if Figure 22 As shown in FIG. 1 , the configurations of the characteristic setting unit 7h and the distance calculation unit 8i in the processing unit 5i are different from those in the first embodiment. The characteristic setting unit 7h has the same configuration as that of the setting unit described in the seventh embodiment.

[0234] The distance calculation unit 8i includes a filter unit 82b, two distance measuring units 81 and 81e, and a switching unit 83.

[0235] The filter unit 82b and the distance measuring unit 81 operate in the same manner as the distance calculating unit 8b described in the third embodiment. The filter unit 82b and the distance measuring unit 81 correspond to the first processing unit.

[0236] The distance measuring unit 81e operates in the same manner as the distance calculating unit 8e described in the fifth embodiment. The distance measuring unit 81e corresponds to the second processing unit.

[0237] The switching unit 83 operates in the same manner as the switching unit described in the eighth embodiment.

[0238] [9-2. Effect]

[0239] According to the ninth embodiment described in detail above, the same effects as those of the eighth embodiment can be obtained.

[0240] [10. Tenth embodiment]

[0241] [10-1. Differences from the First Embodiment]

[0242] The basic structure of the tenth embodiment is the same as that of the first embodiment, so the following description will focus on the differences.

[0243] In the tenth embodiment, the configurations of a characteristic setting unit 7j and a distance calculation unit 8j in a processing unit 5j are different from those in the first embodiment.

[0244] like Figure 25 As shown, the characteristic setting unit 7j includes a baseline calculation unit 73, a peak calculation unit 74, and a threshold setting unit 75j.

[0245] The baseline calculation unit 73 and the peak calculation unit 74 are the same as those described in the fifth embodiment. In other words, the baseline calculation unit 73 calculates the independent baseline value N for each light receiving information. m , and calculate the cumulative baseline value Ns, the peak value calculation unit 74 calculates the maximum light receiving amount S for each light receiving information m .

[0246] The threshold setting unit 75 j includes a primary threshold setting unit 755 and a secondary threshold setting unit 756 .

[0247] Similar to the deviation calculation unit 753 described in the seventh embodiment, the primary threshold setting unit 755 calculates the permissible deviation G×σ of the baseline value. The primary threshold setting unit 755 then outputs the value obtained by adding the accumulated baseline value Ns to the calculated permissible deviation G×σ as the primary threshold TH1. Alternatively, a predetermined fixed value D may be used, and the primary threshold TH1 may be the larger of G×σ+Ns or D+Ns.

[0248] The secondary threshold setting unit 756 calculates the maximum relative peak value Smax similarly to the maximum extraction unit 751 described in the fifth embodiment. The secondary threshold setting unit 756 then adds the difference α and the cumulative baseline value Ns to the calculated maximum relative peak value Smax and outputs the value as the secondary threshold TH2.

[0249] In other words, the primary threshold TH1 is set using either equation (15) or (16), and the secondary threshold TH2 is set using equation (17).

[0250] TH1=G×σ+Ns (15)

[0251] TH1=D+Ns (16)

[0252] TH2=Smax+α+Ns (17)

[0253] In addition, in general, if Figure 26 As shown, the relationship between the primary threshold TH1 and the secondary threshold TH2 is TH1 < TH2. However, when the deviation of the baseline is large and the peaks of the reflected light and the disturbance light are small, there is a case where TH1 ≥ TH2.

[0254] The distance calculation unit 8j includes a distance measuring unit 81j and a filtering unit 82j.

[0255] The ranging unit 81j extracts pulse waveforms having a peak value greater than the primary threshold value TH1 from the accumulated light reception information and calculates the distance R to the object based on the reception timing of each of the extracted pulse waveforms. The ranging unit 81j then generates echo information EC that associates the distance R with the peak value P. Hereinafter, the peak value of the echo information EC is referred to as the echo peak value. The ranging unit 81j may also sort the generated echo information EC in descending order of the echo peak value P.

[0256] Hereinafter, the number of echo information EC generated by the distance measuring unit 81j is referred to as the detected echo number K. K is an integer greater than or equal to 0. Among the generated echo information EC, the echo information having the kth largest echo peak value P is expressed as EC(k), its echo peak value is expressed as P(k), and the distance is expressed as R(k).

[0257] Next, use Figure 27 The flowchart shown here explains the details of the processing in the filtering unit 82j.

[0258] This process is activated every time the distance measuring unit 81 j executes distance measuring processing on the accumulated light reception information based on the accumulated light reception information generated by the light reception integrating unit 6 .

[0259] In S110 , the filter unit 82 j determines whether the number of detected echoes K is equal to or greater than 1. If K≧1, the process proceeds to S120 , and if K<1, the process ends.

[0260] In S120, the filter unit 82j initializes a count value Cnt indicating the number of valid echo information based on reflected waves from objects in the echo information EC detected by the ranging unit 81j, and an index k used to identify the echo information EC. Specifically, the count value Cnt is initialized to 0, and the index k is initialized to 1. Echo information other than valid echo information, i.e., echo information based on interference waves, etc., is referred to as invalid echo information.

[0261] In S130, the filter unit 82j determines whether the echo peak value P(k) of the echo information EC(k) is greater than the secondary threshold value TH2. If P(k)≤TH2, the process moves to S140; if P(k)>TH2, the process moves to S150.

[0262] In S140 , the filter unit 82 j sets a value False indicating invalid echo information to the flag Flg(k) indicating whether the echo information EC(k) is valid echo information or invalid echo information, and proceeds to S170 .

[0263] In S150 , the filter unit 82 j increases the count value Cnt by 1.

[0264] Next, in S160 , the filter unit 82 j sets the flag Flg(k) to a value of True indicating that the signal is valid echo information, and proceeds to S170 .

[0265] In S170 , the filter unit 82 j increments the index k by 1.

[0266] In S180 , the filter unit 82 j determines whether the index k is less than or equal to the number of detected echoes K. If k≦K, the process returns to S130 , and if k>K, the process ends.

[0267] The count value Cnt obtained as a result of this processing is also referred to as the valid echo number. Furthermore, assigning the flag Flg(k) = True to echo information EC(k) is equivalent to validating echo information EC(k), while assigning the flag Flg(k) = False to echo information EC(k) is equivalent to invalidating echo information EC(k). The invalidated echo information EC(k) can be either discarded or provided to subsequent processing along with the validated echo information EC(k).

[0268] [10-2. Effect]

[0269] According to the tenth embodiment described in detail above, the effect (1a) of the first embodiment described above is achieved, and the following effects (10a) and (10b) are achieved.

[0270] (10a) In this embodiment, two threshold values ​​TH1 and TH2 are used to generate echo information EC based on the accumulated light reception information in two stages, and valid echo information is extracted. In other words, the same effect as in the fifth embodiment, in which valid echo information is extracted using the larger threshold value between TH1 (i.e., G×σ+Ns or D+Ns) and TH2 (i.e., Smax+α+Ns), can be achieved.

[0271] (10b) In this embodiment, the use of two thresholds TH1 and TH2 increases the degree of freedom in device configuration. In other words, if an IC that generates only TH1 or an IC that generates only TH2 already exists independently, these ICs can be used to flexibly configure the device.

[0272] [10-3. Modification]

[0273] When the light receiving integration unit 6 is configured to calculate the accumulated light receiving information with Ns = 0, the secondary threshold value setting unit 756 may use the value calculated using the right sides of equations (1) to (3) instead of equation (17) as the secondary threshold value TH2. Furthermore, when the light receiving integration unit 6 is configured to integrate a plurality of light receiving information using a non-zero baseline sequential integration method, the secondary threshold value setting unit 756 may use the value calculated using the right sides of equations (4) to (7) instead of equation (17) as the secondary threshold value TH2.

[0274] [11. Eleventh embodiment]

[0275] [11-1. Differences from the Tenth Embodiment]

[0276] The basic structure of the eleventh embodiment is the same as that of the tenth embodiment, so the following description will focus on the differences.

[0277] In the eleventh embodiment, the configuration of a distance calculation unit 8k in a processing unit 5k is different from that in the tenth embodiment.

[0278] like Figure 28 As shown in FIG. 8 , the distance calculation unit 8k includes a distance measuring unit 81j, a filter unit 82j, and a detection determination unit 85. The distance measuring unit 81j and the filter unit 82j are the same as those described in the tenth embodiment.

[0279] The detection determination unit 85 determines whether or not the effective echo information is appropriately extracted based on the number of detected echoes K obtained by the distance measuring unit 81 j and the number of effective echoes Cnt obtained by the filtering unit 82 j .

[0280] use Figure 29 The flowchart shown here explains the details of the processing of the detection and determination unit 85.

[0281] This process is activated every time a process is executed in the filter unit 82j.

[0282] In S210 , the detection determination unit 85 determines whether the number of detected echoes K is greater than 0 and the number of valid echoes Cnt is 0. If the determination is positive, the process proceeds to S220 ; if the determination is negative, the process proceeds to S230 .

[0283] In S220 , the detection determination unit 85 sets the detection status E_ST to “not detected” indicating that there is a possibility that no valid echo is included among the K echoes detected using the primary threshold TH1 but invalidated by the secondary threshold TH2 , and ends the process.

[0284] In S230 , the detection determination unit 85 sets the detection status E_ST to “detected” indicating that a valid echo has been properly detected, and ends the process.

[0285] In other words, if the peak value of the echo based on the reflected wave from the object (hereinafter referred to as the reflected echo) in the received light information is greater than the peak value of the echo based on the interference wave (hereinafter referred to as the interference echo), the secondary threshold value TH2 is set based on the peak value of the reflected echo. In this case, the peak value of the reflected echo, as integrated by the received light integrating unit 6, is greater than the secondary threshold value TH2, so the echo information of the reflected echo is extracted as valid echo information. On the other hand, the peak value of the interference echo does not change even after integration by the received light integrating unit 6, and remains less than the secondary threshold value TH2, so the echo information of the interference echo is extracted as invalid echo information.

[0286] In contrast, Figure 30As shown, if the peak value of the interference echo in the received light information is greater than the peak value of the reflected echo, the secondary threshold TH2 is set based on the peak value of the interference echo. In this case, the secondary threshold TH2 may be greater than the peak value of the integrated reflected echo, so there is a possibility that the echo information of the reflected echo will be extracted as invalid echo information. The "Not Detected" in the detection status E_ST indicates this situation.

[0287] [11-2. Effect]

[0288] According to the eleventh embodiment described in detail above, the effects (1a), (10a), and (10b) of the first and tenth embodiments described above are achieved, and the following effect (11a) is also achieved.

[0289] (11a) In this embodiment, the possibility that the echo information EC of the reflected echo may become invalid echo information due to the presence of the interference echo can be notified to the subsequent processing.

[0290] [11-3. Modification]

[0291] The detection and determination unit 85 may also replace Figure 29 The detection and determination processing shown in FIG. Figure 44 The detection and judgment processing shown.

[0292] In S240 , the detection determination unit 85 determines whether the number of detected echoes K is greater than 0 and the number of valid echoes Cnt is 0. If the determination is positive, the process proceeds to S250 ; if the determination is negative, the process proceeds to S270 .

[0293] In S250 , the detection determination unit 85 sets the detection state E_ST to “with interference” indicating that the K echoes detected using the primary threshold TH1 but invalidated by the secondary threshold TH2 include echoes based on interference waves and cannot be removed.

[0294] Next, in S260 , the detection determination unit 85 returns the flags Flg( 1 ) to Flg(K) of the K pieces of echo information EC( 1 ) to EC(K) to True, indicating that they are valid echo information, and terminates the process.

[0295] In S270 , the detection determination unit 85 sets the detection state E_ST to “no interference” indicating that there is no influence of interference, and ends the process.

[0296] In this case, although there is a possibility that an interference echo may be detected, it is possible to suppress the non-detection of a reflected echo.

[0297] [12. Twelfth embodiment]

[0298] [12-1. Differences from the Tenth Embodiment]

[0299] The basic structure of the twelfth embodiment is the same as that of the tenth embodiment, so the following description will focus on the differences.

[0300] In the twelfth embodiment, the configuration of a distance calculation unit 81 in a processing unit 51 is different from that in the tenth embodiment.

[0301] like Figure 31 As shown in FIG. 8 , the distance calculation unit 81 includes a distance measuring unit 81j, a filter unit 82j, and a valid echo extraction unit 86. The distance measuring unit 81j and the filter unit 82j are the same as those described in the tenth embodiment.

[0302] When there is a possibility that the echo information EC of the reflected echo is determined to be invalid echo information by the filter unit 82 j , the valid echo extraction unit 86 extracts the invalidated echo information as valid echo information.

[0303] use Figure 32 The flowchart shown here will explain the details of the processing in the effective echo extraction unit 86 .

[0304] This process is activated every time a process is executed in the filter unit 82j.

[0305] In S310, the effective echo extraction unit 86 determines whether the number of detected echoes K is greater than 1 and the number of effective echoes Cnt is 0. If the effective echo extraction unit 86 makes an affirmative determination, it determines that there is a possibility that effective echo information has not been properly extracted and the process proceeds to S320. If the effective echo extraction unit 86 makes a negative determination, it determines that effective echo information has been properly extracted and the process ends.

[0306] In S320 , the effective echo extraction unit 86 sets the index k for identifying the echo information EC to 2. The count value (ie, the number of effective echoes) Cnt at this time is 0, and the flag Flg of all the echo information EC is set to the value False indicating invalidity.

[0307] Next, in S330 , the effective echo extraction unit 86 increments the count value Cnt by 1.

[0308] Next, in S340 , the effective echo extraction unit 86 sets a flag Flg(k) indicating whether the echo information EC(k) is effective echo information to a value indicating valid, True.

[0309] Next, in S350 , the effective echo extraction unit 86 increments the index k by 1.

[0310] Next, in S360 , the effective echo extraction unit 86 determines whether the index k is less than or equal to the number of detected echoes K. If k≦K, the process returns to S330 , and if k>K, the process ends.

[0311] Furthermore, the echo information EC detected by the distance measuring unit 81j is sorted in descending order of the echo peak value P. Therefore, as a result of this processing, the echo peak value having the largest value is used as an invalidation condition, and all the echo information EC(2) to EC(K) except the echo information EC(1) that satisfies the invalidation condition is extracted as valid echo information.

[0312] [12-2. Effect]

[0313] According to the twelfth embodiment described in detail above, the effects (1a), (10a), and (10b) of the first and tenth embodiments described above are achieved, and the following effect (12a) is also achieved.

[0314] (12a) In this embodiment, when all echo information EC in the filter unit 82j is set as invalid echo information, by excluding echo information EC(1) as interference echo information, echo information EC(2) to EC(K) other than echo information EC(1) can be extracted as valid echo information.

[0315] [12-3. Modification]

[0316] use Figure 33 The flowchart of FIG. 8 is used to explain a modified example of the processing in the effective echo extraction unit 86. In the processing of the modified example, Figure 32 Compared with the flowchart of , the twelfth embodiment is different from the twelfth embodiment in that S325 is inserted before S330 and that the process is moved to S325 when an affirmative determination is made in S360.

[0317] In S325, it is determined whether the echo peak value P(k) of the echo information EC(k) is smaller than the value obtained by multiplying the secondary threshold TH2 by the constant C. If P(k) < TH2×C, the processing is moved to S330; if P(k) ≥ TH2×C, the processing is moved to S350.

[0318] For example, assume that the baseline value varies within a range of ±B relative to the cumulative baseline value Ns, and the constant C is set to TH2 × C = TH2 - B. In other words, TH2 × C serves as the invalidation threshold. Alternatively, the constant C can be a fixed threshold that can be freely set by the developer.

[0319] According to the processing of this modified example, other echo information having a peak value comparable to the echo peak value P(1) of the echo information EC(1) of the interference echo is also excluded as invalid echo information. Therefore, even when there are multiple interference echoes, valid echo information can be appropriately extracted.

[0320] [13. Thirteenth embodiment]

[0321] [13-1. Differences from the Tenth Embodiment]

[0322] The basic structure of the thirteenth embodiment is the same as that of the tenth embodiment, so the following description will focus on the differences.

[0323] In the thirteenth embodiment, the configuration of a distance calculation unit 8m in a processing unit 5m is different from that in the tenth embodiment.

[0324] like Figure 34 As shown, the distance calculation unit 8m includes a distance measuring unit 81j, a filtering unit 82j, a valid echo extraction unit 86, and a detection and determination unit 85. The distance measuring unit 81j and the filtering unit 82j are the same as those described in the tenth embodiment, the detection and determination unit 85 is the same as that described in the eleventh embodiment, and the valid echo extraction unit 86 is the same as that described in the twelfth embodiment. Furthermore, the detection and determination unit 85 performs determination using the valid echo number Cnt obtained as a result of processing by the valid echo extraction unit 86.

[0325] [13-2. Effect]

[0326] According to the thirteenth embodiment described in detail above, the effects (1a), (10a), (10b), (11a), and (12a) of the first embodiment and the tenth to twelfth embodiments described above are achieved.

[0327] [14. Fourteenth embodiment]

[0328] [14-1. Differences from the Thirteenth Embodiment]

[0329] The basic structure of the fourteenth embodiment is the same as that of the thirteenth embodiment, so the following description will focus on the differences.

[0330] In the fourteenth embodiment, the configurations of a characteristic setting unit 7n and a distance calculation unit 8n in a processing unit 5n are different from those in the thirteenth embodiment.

[0331] like Figure 35As shown, the characteristic setting unit 7n includes a baseline calculation unit 73, a peak calculation unit 74, a threshold setting unit 75j, and a peak deviation calculation unit 76. Components other than the peak deviation calculation unit 76 are the same as those described in the tenth embodiment.

[0332] The peak deviation calculation unit 76 uses the maximum light reception timing t ... m Calculate the degree of deviation.

[0333] use Figure 36 The flowchart of FIG. 1 illustrates details of the processing executed by the peak deviation calculation unit 76 .

[0334] In S410 , the deviation calculation unit 76 initializes a deviation count value V_Cnt indicating the degree of deviation and an index m used for identifying M pieces of light reception information to be accumulated. Specifically, V_Cnt is set to 0 and m is set to 2.

[0335] Next, in S420, the deviation calculation unit 76 determines the maximum light reception timing t m , t m－1 The absolute value of the difference between |t m -t m－1 | is greater than the pre-set threshold β. If |t m -t m－1 |>β, the deviation calculation unit 76 moves the process to S430. If |t m -t m－1 |≤β, the process proceeds to S440. β is set to the maximum value of the allowable variation for considering the same object, for example, based on the measurement cycle, taking into account the time variation of the peak detection timing of the reflected echo from the same object.

[0336] In S430 , the deviation calculation unit 76 increments the deviation counter value V_Cnt by 1, and proceeds to S440 .

[0337] In S440 , the deviation calculation unit 76 increments the index m by 1.

[0338] Next, in S450 , the deviation calculation unit 76 determines whether the index m is less than or equal to the cumulative number M. If m≦M, the process returns to S420 , and if m>M, the process ends.

[0339] In other words, Figure 37As shown in FIG. 1 , among the M light receiving information to be accumulated, the original peak value based on the reflected light from the same object is detected at approximately the same timing. In contrast, the original peak value based on the interference light is detected only at a timing different from the original peak value based on the reflected light. Moreover, when the original peak value based on the interference light is larger than the original peak value based on the reflected light, the maximum light receiving timing of the light receiving information for which the interference light is detected is different from that of the other light receiving information. As a result, for example, Figure 36 In the example, the two timing differences |t2-t1| and |t3-t2| calculated using the maximum light reception timing t2 of the light reception information at which disturbance light is detected are larger than the threshold value β, and the deviation count value V_Cnt is counted up.

[0340] The distance calculation unit 8n is different from the distance calculation unit 8m described in the thirteenth embodiment in that the detection determination unit 85n is configured differently. Figure 32 The processing shown in the flowchart is a processing for removing the echo information EC(1) as invalid echo information and making the echo information other than the echo information EC(1) as valid echo information.

[0341] use Figure 38 The flowchart of FIG. 1 illustrates details of the processing in the detection and determination unit 85n.

[0342] Figure 38 Flowchart and Figure 29 Compared with the flowchart of , the difference lies in that S215 is added between S210 and S220.

[0343] In S215 , the detection determination unit 85 n determines whether the deviation count value V_Cnt is less than or equal to a preset deviation threshold value THv. If V_Cnt>THv, the process proceeds to S220 , and if V_Cnt≤THv, the process proceeds to S230 .

[0344] Deviation threshold THv is set to 2, for example. When THv=2, the process in S215 corresponds to determining whether the number of peaks based on interference waves (ie, interference echoes) among the peaks having the maximum received light amount detected in each light reception information is 1 or less.

[0345] In other words, if there is one or fewer interference echoes detected as peaks with the maximum received light intensity, the effective echo extraction unit 86 considers the echo information of the interference echoes to be invalid echo information, and extracts echo information other than the interference echoes as valid echo information. Therefore, the detection status E_ST value is set to "detected." If there are two or more interference echoes, the effective echo extraction unit 86 may not be able to accurately extract the valid echo information. Therefore, the detection status E_ST value is set to "not detected."

[0346] [14-2. Effect]

[0347] According to the fourteenth embodiment described in detail above, similar to the above-mentioned thirteenth embodiment, the effects (1a), (10a), (10b), (11a), and (12a) of the first embodiment and the tenth to twelfth embodiments are achieved, and the following effect (14a) is achieved.

[0348] (14a) In this embodiment, the extent to which the light reception information contains an interference echo having an original peak value larger than that of the reflected echo is determined based on the deviation in the maximum light reception timing. If the extent is large, the detection state E_ST is set to "not detected." This prevents erroneous echo information affected by the interference echo from being provided to the subsequent stage.

[0349] [14-3. Modification]

[0350] In the fourteenth embodiment, the deviation count value V_Cnt is used in the processing of the detection and determination unit 85n. However, Figure 35 As shown by the dotted arrow in FIG, it can also be used in the processing of the effective echo extraction unit 86. In this case, Figure 32 In the flowchart of FIG. 3 , a step may be inserted immediately before or after S310 so that, when V_Cnt>2, the flag Flg is not rewritten and the processing is terminated.

[0351] [15. Fifteenth embodiment]

[0352] [15-1. Differences from the Tenth Embodiment]

[0353] The basic structure of the fifteenth embodiment is the same as that of the tenth embodiment, so the following description focuses on the differences. Note that the same reference numerals as those of the tenth embodiment denote the same structures, and reference is made to the preceding description.

[0354] In the fifteenth embodiment, the configurations of a characteristic setting unit 7 o and a distance calculation unit 8 o in a processing unit 5 o are different from those in the tenth embodiment.

[0355] like Figure 39 As shown in FIG. 1 , the characteristic setting unit 7o includes a baseline calculation unit 73, a peak calculation unit 74, and a threshold setting unit 75o. The baseline calculation unit 73 and the peak calculation unit 74 are the same as those described in the tenth embodiment.

[0356] The threshold setting unit 75o includes a primary threshold setting unit 755 and a secondary threshold setting unit 756o. The primary threshold setting unit 755 is the same as that described in the tenth embodiment.

[0357] The secondary threshold setting unit 756o sets the maximum light receiving amounts (i.e., original peak values) A1 to A2 calculated by the peak value calculation unit 74 for each light receiving information W(1) to W(M) in descending order. M Then, the mth largest maximum light intensity A m Expressed as TH2(m), M secondary threshold values ​​TH2(1) to TH2(M) are generated and supplied to the distance calculation unit 8o.

[0358] The distance calculation unit 8o includes a distance measuring unit 81j, a filtering unit 82o, and a detection and determination unit 85. The distance measuring unit 81j is the same as that described in the tenth embodiment. The detection and determination unit 85 is the same as that described in the eleventh embodiment.

[0359] use Figure 40 The flowchart shown here explains the details of the processing in the filtering unit 82o.

[0360] This process is activated each time the distance measuring unit 81j outputs the result of the distance measuring process to the accumulated light receiving information generated by the light receiving integrating unit 6. The K pieces of echo information EC(1) to EC(K) supplied from the distance measuring unit 81j are arranged in descending order of the maximum value of the amount of light received in the corresponding pulse-shaped waveform, i.e., the echo peak value P(k), and K ≤ M.

[0361] This treatment and Figure 27 Compared with the flowchart of , it is different in that S135 is executed instead of S130.

[0362] In S135, the filter unit 82o determines whether the peak value P(k) of the echo information EC(k) with the kth highest peak value is greater than the kth highest secondary threshold value TH2(k). If P(k) ≤ TH2(k), the filter unit 82o proceeds to S140. If P(k) > TH2(k), the filter unit 82o proceeds to S150.

[0363] Here, assuming that only one interference echo is detected in any one of the plurality of light reception information, the above-described processing can remove one or more interference echoes having an echo peak value P larger than the integrated reflection echo as invalid echo information.

[0364] [15-2. Effect]

[0365] According to the fifteenth embodiment described in detail above, the effects (1a), (10a), and (10b) of the first and tenth embodiments described above are achieved, and the following effect (15a) is also achieved.

[0366] (15a) According to this embodiment, all echo information of one or more interference echoes having a peak value greater than the echo peak value P of the integrated reflection echo can be removed, thereby improving the reliability of object detection based on the effective echo information finally extracted.

[0367] Furthermore, although the echo information EC is sorted in descending order of echo peak value P in this embodiment, the echo peak value P may be sorted in ascending order and compared with the secondary threshold value TH2 which is similarly sorted in ascending order.

[0368] [16. Sixteenth embodiment]

[0369] [16-1. Assumed situation]

[0370] Before describing the configuration of the sixteenth embodiment, the form of disturbance light assumed in this embodiment will be described.

[0371] In this embodiment, it is assumed that the interference light is the irradiation light from the flash laser radar. The flash laser radar repeatedly transmits light in a relatively short period. In addition, the flash laser radar diffuses the light when projecting light, so the intensity of light per unit area is weaker than that of other types of laser radars. Therefore, not only are multiple interference lights detected in each light receiving information, but the timing of detecting these multiple interference lights also deviates in each light receiving information. As a result, Figure 45 As shown in FIG. 1 , the waveform of the interference light in the accumulated light receiving information has a lower peak value than the value obtained by simply adding the peak values ​​of the interference echoes detected in each light receiving information, and has a wider pulse width that covers the entire time range of the interference light. In this way, the accumulated interference echo may become larger than the second threshold value TH2 and be detected as signal light. In addition, in Figure 45 In order to make the drawing easier to see, the background noise is omitted.

[0372] In this embodiment, even if the interference echo cannot be eliminated under such circumstances, the occurrence of a situation in which the reflected echo is not detected due to the influence of the interference echo is suppressed.

[0373] [16-2. Differences from the Tenth Embodiment]

[0374] The basic structure of the sixteenth embodiment is the same as that of the tenth embodiment, so the following description will focus on the differences.

[0375] In the sixteenth embodiment, the configurations of a characteristic setting unit 7p and a distance calculation unit 8p in a processing unit 5p are different from those in the tenth embodiment.

[0376] like Figure 46 As shown, the characteristic setting unit 7p includes a baseline calculation unit 73, a peak calculation unit 74, a threshold setting unit 75j, and a comparison value setting unit 77. In other words, the characteristic setting unit 7p has a configuration in which a comparison value setting unit 77 is added to the characteristic setting unit 7j in the tenth embodiment.

[0377] The comparison value setting unit 77 calculates the comparison value D for judging the presence or absence of interference and supplies it to the distance calculation unit 8p. As shown in formula (18), the relative peak values ​​S1 to S2 calculated by the peak value calculation unit 74 for each of the plurality of light receiving information are calculated. M The comparison value D is calculated by adding the total value Ssum of the sum to the cumulative baseline value Ns calculated by the baseline calculation unit 73.

[0378] D=Ssum+Ns (18)

[0379] The distance calculation unit 8p includes a distance measuring unit 81j and a filtering unit 82p.

[0380] When the formula (19) is satisfied, the filter unit 82p executes the processing of the filter unit 82j described in the tenth embodiment.

[0381] |D-P(1)|<THp (19)

[0382] P(1) represents the peak value of echo information EC(1), which is the maximum peak value among the K echoes extracted by the distance measuring unit 81j. THp represents the interference threshold. For example, the interference threshold THp is set based on the difference between the sum of the relative peak values ​​detected based on each light receiving information for the same target object and the relative peak value detected based on the accumulated light receiving information for that target object, and the result of experimentally calculating the magnitude and deviation of this difference. Alternatively, the interference threshold THp can be set by multiplying the maximum relative peak value Smax by a coefficient.

[0383] In other words, Figure 47 as well as Figure 48 As shown, the relative peak values ​​S1 to S2 extracted from the M light receiving information are M When the relative peak value based on the interference echo is not included, the comparison value D and the peak value P(1) become approximately the same value. Therefore, if the formula (19) is satisfied, it can be determined that the echo information EC(1) is a reflection echo. In addition, Figure 47 There is no interfering light. Figure 48 This is a situation where the interference light is smaller than the signal light.

[0384] like Figure 49 as well as Figure 50 As shown, the relative peak values ​​S1 to S2 extracted from the M light receiving information are MIn the case of a relative peak value based on an interference echo, the comparison value D is likely to be different from the peak value P(1). Therefore, if the formula (19) is not satisfied, it can be determined that the echo information EC(1) to EC(K) extracted by the distance measuring unit 81j contains an interference echo. In addition, Figure 49 This is when a relative peak based on the interference echo is detected in all the received light information. Figure 50 This is a case where a relative peak based on the interference echo is detected only in one light receiving information.

[0385] [16-3. Effect]

[0386] According to the sixteenth embodiment described in detail above, the effects (1a), (10a), and (10b) of the first and tenth embodiments described above are achieved, and the following effect (16a) is also achieved.

[0387] (16a) In this embodiment, when irradiation light from a flash-type laser radar is received as disturbance light, the influence of the disturbance light can be suppressed, and the reflected light becomes non-detectable.

[0388] [16-4. Modification]

[0389] In this embodiment, when the light receiving integration unit 6 integrates a plurality of light receiving information using a non-zero baseline sequential integration method, and the secondary threshold setting unit 756 sets the maximum original peak value Amax as the secondary threshold value TH2 according to formula (7), the following problem arises. Figure 51 As shown, due to the deviation of interfering light, there is an independent baseline value N m Compared with the original peak value A of the signal light and the interference light m Big situation. Figure 51 , the first light reception information W(1) corresponds to this situation. In this case, A1 is detected as N1. As a result, the accumulated light reception information is equal to the result of accumulating the second to Mth light reception information. In this case, since Amax = A1, the secondary threshold TH2 is set to A1. As a result, all peak values ​​detected in the accumulated light reception information may become smaller than the secondary threshold TH2, and not only interference echoes but also reflected echoes may not be detected.

[0390] Therefore, the filter unit 82p uses the amplitude P(1)=S2+A3 of the echo information EC(1) detected using the primary threshold value TH1 to determine whether or not the equation (20) is satisfied.

[0391] P(1)<MAX(N1, N2, ... N M ) (20)

[0392] If equation (20) is satisfied, the processing of the filter unit 82p using the secondary threshold TH2 is prohibited. For example, if the reflected light is buried by the interference light in any of the received light information, the processing of the filter unit 82p is prohibited, and all the echo information EC(1) to EC(K) extracted using the primary threshold TH1 is provided to the subsequent processing. Although there is a possibility that the interference echo will be mistakenly detected as a reflected echo in the subsequent processing, it is possible to prevent the reflected echo from being undetected.

[0393] [17. Other embodiments]

[0394] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Various deformation|transformation can be carried out.

[0395] (17a) In the determination unit 722 described in the present invention, a range larger than the determination threshold is extracted as a valid range. However, the method for extracting the valid range is not limited to this. For example, another determination threshold may be set for extracting the interference range where the interference light waveform is estimated to exist, and the interference range extracted using the other determination threshold may be set as an invalid range, while the range outside the invalid range may be extracted as a valid range.

[0396] (17b) In the present invention, distance calculation units 8, 8b, 8e, 8h, and 8i are configured to use the processing results of characteristic setting units 7, 7a, and 7d to 7h to remove the calculation results based on the pulse-shaped waveform of interference light. However, this does not necessarily require removal of these calculation results. For example, instead of removing the distance calculated based on the pulse-shaped waveform existing in the invalid range (i.e., the designated range), a flag indicating that the calculated distance is based on interference light may be assigned to the calculated distance. In this case, subsequent processing using the distance calculation results or the user can also take measures to remove the influence of interference light based on the flag.

[0397] (17c) The present invention has been described in terms of using a SPAD as a light receiving element in the light receiving unit 3. However, the light receiving element is not limited to a SPAD. Any light receiving element may be used as long as it can detect temporal changes in received light intensity.

[0398] (17d) The binarization unit 71 of the present invention uses a plurality of light receiving information to be accumulated as the binarized information to be binarized, but the binarized information is not limited to this. For example, when the accumulated number of light receiving information is 3, Figure 23 as well as Figure 24As shown, the binarization unit 71 may also use the first light reception information, the information obtained by accumulating the first and second light reception information, and the information obtained by accumulating the first to third light reception information as the binarized information. In other words, the light reception binary information may be generated by binarizing the light reception waveforms shown in the information sequentially generated during the light reception information accumulation process using a preset binarization threshold value THb.

[0399] When such a binarization unit 71 is used, the accumulated binary information generated by the binary accumulation unit 721 shown in the first embodiment shows an accumulated binary waveform as shown in FIG. Figure 23 As shown, the time range of the detected interference light waveform is Figure 3 The first embodiment shown in FIG is different from the case of FIG. 2. In addition, the waveform shown by the logical AND operation information generated by the logical operation unit 723 shown in the second embodiment is as follows: Figure 24 As shown, it is the same as the case of the second embodiment.

[0400] (17e) In the present invention, in one light emitting unit 2, the output periods T1, T2, T3, ... of the light emitting trigger signal are randomly changed within a constant range, but the setting of the output period of the light emitting trigger signal is not limited to this. For example, Figure 52 As shown in FIG, a plurality of light emitting units 2 may be provided for irradiating light in different irradiation directions. Figure 53 As shown in FIG, the output period can be randomly changed among the plurality of light emitting units 2. Figure 54 As shown, each light emitting unit 2 may have its own output period constant, and the constant value of the output period may be different for each light emitting unit 2. Furthermore, in the case of a configuration such as a laser radar equipped with a scanning mirror, where the scanner is moved so that one light emitting unit 2 emits light in different irradiation directions, the output period may be varied for each irradiation direction.

[0401] (17f) The processing units 5, 5a to 5p and the methods thereof described in the present invention may also be implemented by a dedicated computer provided by a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the processing units 5, 5a to 5p and the methods thereof described in the present invention may also be implemented by a dedicated computer provided by a processor constituted by one or more dedicated hardware logic circuits. Alternatively, the processing units 5, 5a to 5p and the methods thereof described in the present invention may also be implemented by one or more dedicated computers constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored as an instruction executed by a computer in a non-migratable tangible recording medium that can be read by the computer. The method for realizing the functions of each unit included in the processing units 5, 5a to 5p does not necessarily need to include software, and all of its functions may be realized using one or more hardware.

[0402] (17g) It is also possible to implement multiple functions of one component in the above-mentioned embodiment by multiple components, or to implement one function of one component by multiple components. In addition, it is also possible to implement multiple functions of multiple components by one component, or to implement one function implemented by multiple components by one component. In addition, it is also possible to omit a part of the components of the above-mentioned embodiment. In addition, it is also possible to add or replace at least a part of the components of the above-mentioned embodiment with the components of another above-mentioned embodiment.

[0403] (17h) In the technical claims, the method for calculating the cumulative light reception information described in claims 13 and 14 may be applied to the technical claims 20 and later. The method for setting the extraction threshold described in claims 15 to 18 may also be applied to the technical claims 21 and later. In this case, the "extraction threshold" is replaced by the "secondary threshold."

[0404] (17i) In addition to the above-mentioned distance measuring device 1, the present invention can also be implemented in various forms such as a system with the distance measuring device 1 as a component, a program for causing a computer to function as the processing unit 5, 5a~5p of the distance measuring device 1 or a part thereof, a non-migrating physical recording medium such as a semiconductor memory recording the program, and a distance measuring method.

Claims

1. A distance measuring device, wherein: have: a light emitting unit for irradiating light to an object by randomly changing the timing of light emission; a light receiving portion for receiving light reflected from the object; a characteristic setting unit that uses a temporal variation in the amount of received light obtained by the light receiving unit as light receiving information and extracts, based on one or more pieces of the light receiving information, a time range in which reflected light from the object due to the light irradiated from the light emitting unit, i.e., the irradiated light, may exist as an effective range; a light receiving integration unit for generating integrated light receiving information by integrating the light receiving information on a time axis with the light emission timing being aligned over a plurality of light emission events; and The distance calculation unit uses the effective range extracted by the characteristic setting unit to remove the pulse-shaped waveforms generated by pulse light other than the irradiation light from the pulse-shaped waveforms having a peak value greater than an extraction threshold value included in the integrated light reception waveform indicated by the integrated light reception information, i.e., distance noise, and calculates the distance to the object that has reflected the irradiation light by taking the timing at which each of the pulse-shaped waveforms reaches a peak or the timing at the middle of a range where the signal level becomes greater than a certain threshold value as the light reception timing. The distance calculation unit includes: a distance measuring unit that calculates the distance to the object based on a time difference between light emission timing and light reception timing using the accumulated light reception information; and a filtering unit that uses a filter to remove pulse light other than the irradiation light in the cumulative light-receiving information processed by the distance-measuring unit, or to invalidate the pulse light other than the irradiation light in the cumulative light-receiving information processed by the distance-measuring unit, or to reduce the pulse light other than the irradiation light in the cumulative light-receiving information processed by the distance-measuring unit, The characteristic setting unit includes: a binarization unit for generating, for at least one of the binarized information of each of the light reception information and the information sequentially generated in the process of accumulating the light reception information by the light reception accumulating unit, light reception binary information indicating a relationship between time and the binarized information, using a binarization threshold value that is either a preset threshold value or a threshold value calculated based on the binarized information; and The filter generating unit sets filter characteristics of the filtering unit by extracting an effective range indicating a time range in which reflected light from the object due to the irradiation light may exist in the accumulated light reception information using the received light binary information.

2. The distance measuring device according to claim 1, wherein: The filter generation unit includes: a binary accumulation section that accumulates the plurality of pieces of received light binary information generated by the binarization section on a time axis such that the light emission timings are aligned; as well as The determination unit extracts the effective range by binarizing the accumulated light reception binary information using either a preset fixed threshold or a determination threshold calculated based on the number of accumulated light reception binary information.

3. The distance measuring device according to claim 1, wherein: The filter generation unit includes: The logic operation unit extracts the effective range by performing a logic AND operation on the plurality of pieces of the light-receiving binary information generated by the binarization unit on a time axis in which the light-emission timings are aligned.

4. The distance measuring device according to claim 1, wherein: The filter generation unit includes: a binary accumulation section that accumulates the plurality of pieces of received light binary information generated by the binarization section on a time axis such that the light emission timings are aligned; and The normalization unit performs normalization by dividing the accumulated binary information of received light by the number of accumulations in the binary accumulation unit, thereby extracting the effective range and setting a gain within the effective range.

5. The distance measuring device according to any one of claims 1 to 4, wherein: The characteristic setting unit converts the effective range set on the time axis into the effective range on the distance axis to generate the filter. In the distance calculation unit, the distance measuring unit calculates the distance for each pulse waveform in the accumulated light reception information, and the filtering unit applies the filter to the calculated distance to extract the distance included in the effective range of the filter.

6. The distance measuring device according to any one of claims 1 to 4, wherein: The characteristic setting unit generates the filter based on the effective range set on the time axis. In the distance calculation unit, the filtering unit causes the filter to act on the accumulated light reception information to extract a time range included in the effective range, and the distance measuring unit calculates the distance for each pulse-shaped waveform existing in the extracted time range.

7. The distance measuring device according to any one of claims 1 to 4, wherein: In the above-mentioned distance calculation unit, the above-mentioned distance measuring unit calculates the intermediate data required for calculating the distance for each pulse-shaped waveform in the above-mentioned accumulated light-receiving information, and the above-mentioned filtering unit causes the above-mentioned filter to act on the calculated above-mentioned intermediate data, extracts the above-mentioned intermediate data contained in the above-mentioned effective range of the above-mentioned filter, and uses the extracted intermediate data to calculate the distance to the above-mentioned object.

8. The distance measuring device according to claim 7, wherein: The characteristic setting unit converts the effective range set on the time axis into the effective range on the distance axis to generate the filter. The distance calculation unit causes the filter to act on the intermediate data converted into data on the distance axis.

9. The distance measuring device according to claim 7, wherein: The characteristic setting unit generates the filter based on the effective range set on the time axis. The distance calculation unit causes the filter to act on the intermediate data, which is data on the time axis.

10. The distance measuring device according to claim 1, wherein: The distance calculation unit includes: A first processing unit, comprising the distance measuring unit and the filtering unit; a second processing unit including a second distance measuring unit that uses each pulse waveform extracted from the accumulated light reception information using a second extraction threshold as a detection target and calculates the distance to the object based on a time difference between the light emission timing and the light reception timing; and a switching unit that outputs either a processing result of the first processing unit or a processing result of the second processing unit according to a preset switching condition, The characteristic setting unit includes: a first characteristic setting unit including the binarization unit and the filter generation unit, and setting the characteristics of the filter used in the filtering unit; and The second characteristic setting unit sets the second extraction threshold used in the second distance measuring unit. The second characteristic setting unit includes: a baseline calculation unit, which calculates, as a target information group, a plurality of the light reception information to be accumulated by the light reception accumulation unit, a baseline value of each of the light reception information belonging to the target information group, namely, an independent baseline value, and a baseline value of the accumulated light reception information, namely, an accumulated baseline value, wherein the baseline value is an average value or a median value of the amount of light received detected within a time range excluding a time range affected by reflected light, interfering light, and clutter; a peak value calculating unit for calculating, for each of the light receiving information belonging to the target information group, at least one of an original peak value, which is a maximum value of the amount of light received within a time range of at least a portion of the light receiving information, and a relative peak value obtained by subtracting the independent baseline value from the original peak value; as well as The threshold setting unit sets the second extraction threshold using at least one of the independent baseline value and the cumulative baseline value, and at least one of the original peak value and the relative peak value.

11. The distance measuring device according to claim 10, wherein: The light reception integrating unit calculates the cumulative light reception information so that the cumulative baseline value becomes zero.

12. The distance measuring device according to claim 10, wherein: The light reception integrating unit calculates the cumulative light reception information so that the cumulative baseline value becomes non-zero.

13. The distance measuring device according to any one of claims 10 to 12, wherein: The peak value calculation unit calculates at least the relative peak value. The threshold setting unit includes: The maximum extraction unit sets a result obtained by adding the cumulative baseline value to the maximum value of the relative peak values ​​calculated for each of the light receiving information belonging to the target information group as the second extraction threshold value.

14. The distance measuring device according to any one of claims 10 to 12, wherein: The peak value calculation unit calculates at least the original peak value. The threshold setting unit includes: The maximum extraction unit takes the maximum value of the above-mentioned original peaks calculated for each of the above-mentioned light-receiving information belonging to the above-mentioned object information group as the maximum original peak, and any one of the above-mentioned independent baseline value of the above-mentioned light-receiving information that will become the extraction source of the above-mentioned maximum original peak and the average value of the above-mentioned independent baseline value calculated for each of the above-mentioned light-receiving information belonging to the above-mentioned object information group as the compensation value, and sets the result after subtracting the above-mentioned compensation value from the above-mentioned maximum original peak and adding the above-mentioned cumulative baseline value as the above-mentioned second extraction threshold.

15. The distance measuring device according to claim 12, wherein: The peak value calculation unit calculates at least the original peak value. The threshold setting unit includes: The maximum extraction unit sets a maximum original peak value, which is a maximum value among the original peak values ​​calculated for the light reception information items belonging to the target information group, as the second extraction threshold value.

16. The distance measuring device according to claim 13, wherein: The threshold setting unit sets the second extraction threshold by adding a difference between a predetermined constant and a value set according to a calculation result of the baseline calculation unit or the peak calculation unit.

17. The distance measuring device according to claim 13, wherein: The baseline calculation unit calculates the allowable deviation value using, in addition to the independent baseline value and the cumulative baseline value, either a deviation of the independent baseline value or a deviation of the cumulative baseline value. The threshold setting unit further includes: a deviation calculation unit that adds the allowable deviation value to the cumulative baseline value; and The threshold selection unit selects a maximum value among the calculation result of the maximum extraction unit, the calculation result of the deviation calculation unit, and a preset fixed value, and sets the maximum value as the second extraction threshold value.

18. The distance measuring device according to claim 1, wherein: The distance calculation unit includes: A first processing unit, comprising the distance measuring unit and the filtering unit; a second processing unit including a second distance measuring unit that uses a second extraction threshold to extract each pulse waveform from the accumulated light reception information as a detection target and calculates the distance to the object based on a time difference from light emission to light reception; as well as a switching unit that outputs either a processing result of the first processing unit or a processing result of the second processing unit according to a preset switching condition, The characteristic setting unit further includes: a baseline calculation unit that calculates a cumulative baseline value representing a baseline value of the cumulative light reception information generated by the light reception integration unit, the baseline value being an average value or a median value of the light reception amounts detected within a time range excluding a time range affected by reflected light, interfering light, and clutter; a peak value calculation unit that calculates a relative peak value obtained by subtracting the cumulative baseline value from a maximum value within a time range of at least a portion of the cumulative light reception information; and A threshold setting unit sets the second extraction threshold using the cumulative baseline value and the relative peak value. The threshold setting unit includes: The division unit takes the multiple light receiving information to be accumulated in the light receiving accumulation unit as an object information group, and sets the result of adding the division value of the relative peak value calculated by the peak calculation unit by the number of the light receiving information belonging to the object information group, that is, the cumulative number, the cumulative baseline value, and any one of the values ​​calculated based on a predetermined constant and the division value as the second extraction threshold.

19. The distance measuring device according to claim 1, wherein: The characteristic setting unit further includes: a baseline calculation unit, which calculates, as a target information group, a plurality of the light receiving information to be accumulated by the light receiving accumulation unit, a baseline value of each of the light receiving information belonging to the target information group, namely, an independent baseline value, and a baseline value of the accumulated light receiving information, namely, an accumulated baseline value, and calculates a permissible deviation value using either a deviation of the independent baseline value or a deviation of the accumulated baseline value, wherein the baseline value is an average value or a median value of the amount of light received detected within a time range excluding a time range affected by reflected light, interfering light, and clutter; a peak value calculating unit for calculating, for each of the light receiving information belonging to the target information group, at least one of an original peak value, which is a maximum value of the amount of light received within a time range of at least a portion of the light receiving information, and a relative peak value obtained by subtracting the independent baseline value from the original peak value; a primary threshold value setting unit that sets a primary threshold value using the cumulative baseline value and the allowable deviation value; and a secondary threshold setting unit that sets a secondary threshold using at least one of the independent baseline value and the cumulative baseline value, and at least one of the original peak value and the relative peak value; The distance calculation unit includes: A first processing unit, comprising the distance measuring unit and the filtering unit; a third processing unit; and a switching unit that outputs either a processing result of the first processing unit or a processing result of the third processing unit according to a preset switching condition, The third processing unit includes a third distance measuring unit that uses each pulse waveform extracted from the accumulated light reception information using the primary threshold as a detection target and generates echo information based on a time difference between light emission and light reception, the echo information including an object distance, which is a distance to the object, and an echo peak, which is a peak value of the light reception amount in the pulse waveform corresponding to the object distance; as well as The second filtering unit validates or invalidates the echo information generated by the third distance measuring unit using the secondary threshold.

20. The distance measuring device according to claim 19, wherein: The second filter unit invalidates the echo information by removing the echo information having the echo peak value smaller than the secondary threshold value as invalid echo information.

21. The distance measuring device according to claim 19, wherein: The second filter unit extracts the echo information having the echo peak value equal to or greater than the secondary threshold value as valid echo information to validate the information.

22. The distance measuring device according to claim 21, wherein: The third processing unit further comprises: The detection and determination unit performs at least one of the following determinations: when the number of the echo information generated by the third ranging unit, that is, the number of detected echoes, is greater than 0, and the number of the valid echo information extracted by the second filtering unit, that is, the number of valid echoes, is 0, a determination is made that there is interference, indicating that the echo information includes information based on the interference wave; and when the number of the valid echo information is greater than 1, a determination is made that there is no interference, indicating that the valid echo information does not include information based on the interference wave.

23. The distance measuring device according to claim 21, wherein: The third processing unit further comprises: The detection and determination unit performs at least one of the following determinations: when the number of the echo information generated by the third ranging unit, that is, the number of detected echoes, is greater than 0, and the number of the valid echo information extracted by the second filtering unit, that is, the number of valid echoes, is 0, a determination is made that there is a possibility that an undetected object exists; and when the number of the valid echo information is greater than 1, a determination is made that an object is properly detected.

24. The distance measuring device according to claim 23, wherein: The characteristic setting unit further includes: The deviation calculation unit calculates the timing difference between the light receiving information to obtain the maximum light receiving amount, uses a predetermined fixed value or a variable value set according to the cumulative baseline value as a judgment threshold, and calculates the number of times the timing difference is greater than the judgment threshold, that is, the number of peak deviations. The detection determination unit determines that an object has been properly detected when the number of peak deviations is equal to or smaller than a preset deviation threshold.

25. The distance measuring device according to any one of claims 21 to 23, wherein: The third processing unit further comprises: The effective echo extraction unit extracts all the above-mentioned echo information other than the above-mentioned echo information whose echo peak value satisfies a preset invalid condition as the above-mentioned effective echo information when the number of the above-mentioned echo information detected by the above-mentioned third ranging unit, that is, the detected echo number, is greater than 1 and the number of the above-mentioned effective echo information extracted by the above-mentioned second filtering unit, that is, the effective echo number, is 0.

26. The distance measuring device according to claim 25, wherein: The maximum echo peak value is used as the invalidation condition.

27. The distance measuring device according to claim 25, wherein: A value obtained by subtracting the allowable deviation amount of the cumulative baseline value from the largest echo peak value is used as an invalidation threshold, and the invalidation condition is that the echo peak value is greater than the invalidation threshold value.

28. The distance measuring device according to claim 25, wherein: The characteristic setting unit further includes: The deviation calculation unit calculates the timing difference between the light receiving information to obtain the maximum light receiving amount, uses a predetermined fixed value or a variable value set according to the cumulative baseline value as a judgment threshold, and calculates the number of times the timing difference is greater than the judgment threshold, that is, the number of peak deviations. The effective echo extraction unit extracts the effective echo information when the number of peak deviations is equal to or smaller than a preset deviation threshold.

29. The distance measuring device according to claim 25, wherein: The secondary threshold setting unit sets a plurality of secondary thresholds based on the maximum light intensity extracted for each light receiving information. The second filtering unit extracts the valid echo information by combining the echo peak value and the secondary threshold value in either a descending order or a descending order, and comparing the magnitude relationship between the two.

30. The distance measuring device according to any one of claims 19 to 24, wherein: The characteristic setting unit further includes: a comparison value setting unit for setting a comparison value obtained by adding the cumulative baseline value to the total value of the relative peak values ​​calculated for each of the light receiving information belonging to the target information group; The second filter unit validates all of the echo information when a difference between the comparison value and a maximum value among the echo peak values ​​is larger than a preset threshold value.

31. The distance measuring device according to any one of claims 19 to 24, wherein: The characteristic setting unit further includes: The comparison value setting unit sets the maximum value among the independent baseline values ​​calculated for each of the light receiving information belonging to the target information group as a comparison value, The second filter unit validates all of the echo information when a maximum echo peak value having the largest echo peak value in the echo information is smaller than the comparison value.

32. The distance measuring device according to claim 1, wherein: The light emitting unit is configured to emit light in a plurality of irradiation directions, and the intervals of the timing of emitting light are different for each of the irradiation directions.

Images